# Up Front Bass -- Just an Illusion?



## mattyjman (Aug 6, 2009)

Okay, want to generate some thoughtful conversation here on achieving up front bass. 

So, here are my thoughts... 

It's possible to achieve "up front bass" illusion with a well integrated mid and sub. 

It's not possibly to achieve "up front bass IMPACT" without a decent sized, high output midbass driver in the front of the car. 

I think there is a disconnect between these two results and most people are looking for a high impact up front bass solution, while many preach on here the ability to cleverly trick the mind with T/A and phasing, eq, etc. all the while using smaller mids...

While I don't disagree, what happens when you get any sort of volume from the system that only provides the illusion of upfront bass. As volume increases, the "up front bass illusion" slowly drags itself closer and closer to the rear of the vehicle. Is it _really_ possible to achieve dynamic up front bass while using 6.5 mids or lower powered or lower xmax drivers? Or is it just an illusion that will fade away as volume increases? 

I would wager that it is not possible to really achieve the impact without more cone area in the front. 

Watching BowDown's thread and putting a sub up in his dash has got me thinking a bit more about how to achieve the "impact" that so many of us want. I have also recently finished my install, and have high output 8" midwoofers pulling midbass duty while three 10 wgti subs anchor the low down. The impact is seamless, and ALL up front. No matter how loud I turn it up, the stage and impact stays up front. 

I'm not sure putting a sub in the front is the most efficient way of getting bass up front. While I am hoping to generate some thoughtful comments from those who are in the know, I think the take away for this is that you can't simply have the impact in the front that you want without increasing the effective cone area in the front of the car. 

Thoughts?


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## BigRed (Aug 12, 2007)

You can have a sub in the front and if it resonates thru the cabin at all it will sound like it's coming from somewhere else

Big midbass's do help


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## lycan (Dec 20, 2009)

First, it makes sense to define "where", in frequency, the desired "impact" comes from.

Imagine a big-ass kettle drum, for example. Strike that drum ... you want to "feel" that impact. If you examine the response of that drum, in time, you'll find an initial "attack", followed by a longer decay or "tail".

It's important to realize that the initial "attack" is much HIGHER in frequency than you think. The "attack" does not come from your subs, it comes from other drivers in your system. If the crossover is well-integrated, all drivers together create a seamless reproduction ... in frequency, and in time. And you don't need subs upfront, to create the "impact" of the attack upfront.

If you haven't done so already, try this : find a system that's tuned great. Play some great music, with the "impact" you're looking for. Then, turn off ALL drivers in the system EXCEPT the subs. Shut them all OFF, except the subs. Re-play the exact same tracks.

Is the "impact" still present?

Now, i'm not arguing against some stout midbass drivers  I'm just saying that, for the most part, the lowest octave (or maybe two) isn't where the real "impact" is.


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## ncv6coupe (Oct 25, 2009)

Matty, I can definately say that a 6.5" can have all the impact you require up to a certain spl of course but it can hang up to 100-105db and keep the bass well up front, don't attempt unless its deep up in the kick panel corner loaded off-axis though. Rite now i don't even run the full system, i use my factory radio powering some fiberblob-kick panels i threw together and suprising it can shake my clothes and thats with cheap generic speakers in them too.

oh forgot to say, you should hear mic10is's bmw if you want up front bass impact!


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## FAUEE (Jul 22, 2010)

This is actually something I've been thinking about lately myself. In my case, I've got some nice beefy fronts (Kicker QS 65.2 - don't hate on the Kickers, they actually sound very good), but my SUV has a very far forward position for the front speakers. So basically, even though my speakers are pretty beefy (and put out great midbass sound wise) they never feel beastly, the far less impressive Infinity Reference components in my gf's PT Cruiser feel much more authoritative since they're right on your leg up by you.

I've had 2 major lines of though on how to correct this. First is the method of adding a front subwoofer (given my design limitations, it'd have to be small, probably a 6" woofer, and this would possibly cause issues with my actual sub stage. Amplifying it would also be a possible issue, and mounting would require either significant modifications to my center console, or be run under the front seats, which don't have much room (plus this is where my tool kit and power inverter are housed).

The other option is basically what we're discussing. I don't *need* more front bass or midbass. I need more impact from it. So it's possible that a tactile transducer such as the Auras on PE (or better yet the Daytons, they're cheaper and require less power, meaning I can run them off my HU as opposed to needing another amp - my HU lets me set the rear speaker outputs to sub outputs) may work well. This could provide the extra "kick" I'm looking for, without me needing to go the actual sub route.

I've never used tactile transducers before, anyone have any thoughts about this idea?


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## mattyjman (Aug 6, 2009)

lycan said:


> First, it makes sense to define "where", in frequency, the desired "impact" comes from.
> 
> Imagine a big-ass kettle drum, for example. Strike that drum ... you want to "feel" that impact. If you examine the response of that drum, in time, you'll find an initial "attack", followed by a longer decay or "tail".
> 
> ...


this is exactly what i was getting at.... up front bass and impact don't necessarily mean that all bass frequencies need to come from the front, but rather the frequencies that create that dynamic or impact need to. how well will a 6" driver do this vs a 8 or a 10" driver. the more cone area reproducing those frequencies, the higher "impact" you'll get from them, thus creating the illusion and impact of up front bass.


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## Mic10is (Aug 20, 2007)

ncv6coupe said:


> oh forgot to say, you should hear mic10is's bmw if you want up front bass impact!




Except its in rebuild mode right now. adding more fun


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## sqnut (Dec 24, 2009)

lycan said:


> First, it makes sense to define "where", in frequency, the desired "impact" comes from.
> 
> Imagine a big-ass kettle drum, for example. Strike that drum ... you want to "feel" that impact. If you examine the response of that drum, in time, you'll find an initial "attack", followed by a longer decay or "tail".
> 
> ...


++++ ad infinitum

The first lycan post I can relate to and understand. I'm just dumb with maths and physics. C'mon bro admit that you went the last mile by your ears. Also that you're back to stock cause you realised that car audio has physical limitations. It's like crossing one hurdle after another. Eats up too much time and at some point you have to let it go to allocate time better. 

Impact is what tickles your entire body from head to toe across the 10 octaves. It's not just about the chest thump over 2 octaves. Hearing the root and decay of a 70hz piano note is way different from the sub slamming your chest/kidneys. 


Mic10is said:


> Except its in rebuild mode right now. adding more fun


Why are sq installs, tuning settings always wip? That said, I would love to hear your bmw, Mac's Edge (which he hates), Kirks Accura............as long as ya'll don't give me the 'shyt tune'.

Disclaimer : Both posts made TIC (Tongue in cheek). You're both learning pools for me. Just talk in a language that I can understand.


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## quality_sound (Dec 25, 2005)

If you want to remove the feeling of the bass coming form behind you then you have to remove the cues that it coming from behing you. The biggest obstacle is, of course, your seat back. You don't need a sub up front, or even massive midbasses, to get impact in the front. You just need to do it right.


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## Mic10is (Aug 20, 2007)

quality_sound said:


> If you want to remove the feeling of the bass coming form behind you then you have to remove the cues that it coming from behing you. The biggest obstacle is, of course, your seat back. You don't need a sub up front, or even massive midbasses, to get impact in the front. You just need to do it right.


Thats kind of a vague statement. Please explain what you mean by " do it right"


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## mattyjman (Aug 6, 2009)

quality_sound said:


> If you want to remove the feeling of the bass coming form behind you then you have to remove the cues that it coming from behing you. The biggest obstacle is, of course, your seat back. You don't need a sub up front, or even massive midbasses, to get impact in the front. You just need to do it right.


Id wager that you can't get big impact up front without a decent sized midbass unless your subs are playing into the midwoofer ranges, which i don't know of anyone that is doing that. If the impact doesn't come from sub ranges like lycan said, then if you have a mid that simply can't produce those mid frequencies with any authority then you wont get the up front bass impact. You might get the illusion at low volumes but turn it up to have any fun and it'll drag your ears right to the back of the cabin.

The reason i started thinking about this is because i recently had two processors that "auto tune" and they came up with varying concepts or results in the midbass range. One was preached as a tool that would get up front bass with any speakers, and the other simply as a good start. The processor that preached up front bass abilities killed my midbasses. At low volumes, it was right. It sounded up front but at any sort of "fun" volume, the bass was clearly coming from the rear. Contrast that with the othe
r processor and with its reliance on good midbass drivers allowed my system to not only have upfront bass at low volumes but also the impact and illusion at high volumes too


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## sqnut (Dec 24, 2009)

cajunner said:


> this thing people keep talking about, "chest-hitting bass" and "frontal impact", are really just the resonant chambers of your upper thoracic cavity responding to sound waves. The reason you focus on those sound waves that you feel in your chest as if they were coming from behind you, is because the seatback isn't fully mass-loaded to the point where it's resonant frequency is sufficiently low to prevent tactile vibration from transferring to your skin. If you have a bass tone that hits, and you feel it only in your chest, then does it matter where the wave propagated from, in a closed pressurization chamber?
> 
> That's what everyone wants but because it's rare to see people adding lead to their seat structure and replacing foam batting that responds to sound waves, with foam that is less transmissive, then you will continue to see the beleaguered competitor complain that no matter what he does he can't shake the "bass in rear" localization, as it's difficult to live with a daily driver that has hard appointments to the seating.



Total and utter crap. You just proved once again that you don't have the sound.


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## Niebur3 (Jul 11, 2008)

I have very large midbass in my doors (MW182's) and I can blend very well with the sub I have in the rear of the car (hatch car). With that said, I have noticed the exact thing cajunner stated and if I mute my sub and drop crossover point on my midbass to play all the way down to 20hz and I still get cues that the bass is coming from the rear at certain frequencies. I noticed my seat back vibrating from my door speakers. Which lead me to think it is not my sub in the back causing cues that the bass is coming from the rear, it is my seat back vibrating.


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## sqnut (Dec 24, 2009)

May be a bit subjective for you, but here goes.

*1. Phase Coherence : * 99% of the folks who use TA are aiming for exact same arrival times for sub/mid/high frequencies. Here's what I'm aiming for. I want the sub frequencies to hit me a fraction before the mids hit me together which would hit me a further fraction of of a second before the highs. Hearing the highs (which have all the height cues) last and from a physically higher height, drags the stage up. Measured distance is only a starting point. From there on I delay everything in equal proportion and then break the proportion right at the end. Its all about hearing here.

*2. Sub / Mid Blending:* Balance across all 10 octaves along with balance across L/R is what you're aiming for. RTA flat does not equal balance. Typically your sub i s playing 50-70hz much louder than 20-40hz. Your mid is just kicking in around 50hz and is into its elements around 100hz. Hence the blend from 50-100hz is critical to getting the right balance. Again you have to hear this to set it. In my set up I have to pinch down at 50hz, balance 80hz with 50 while pulling 80 towards me. Its almost a iven that you cant cross over higher than 60hz and hope to maintain this balance. Oh and another point, if you xover higher than 60hz then you're clue less.

*3. Impact : * You don't need a lead shield to block the sub wave from the rear. Phase correction and balancing will set it up nicely. Impact is what you feel over 8-10 octaves not just over 2 octaves.

Kapish?......


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## sqnut (Dec 24, 2009)

cajunner said:


> I disagree.
> 
> phase coherence between sub/mid/high frequencies? No, I just time everything to hit at once.


You don't have the vaguest clue, leave alone the sound.


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## traceywatts (Jun 2, 2008)

sqnut said:


> You don't have the vaguest clue, leave alone the sound.


Im going slightly off topic, here. SQNUT, YOU ARE ABRASIVE. Your message can be conveyed without insulting the intelligence of others. This is a forum to teach and learn, not one to insult and degrade. Please teach, or learn. Nothing more.

Thank You


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## sqnut (Dec 24, 2009)

traceywatts said:


> Im going slightly off topic, here. SQNUT, YOU ARE ABRASIVE. Your message can be conveyed without insulting the intelligence of others. This is a forum to teach and learn, not one to insult and degrade. Please teach, or learn. Nothing more.
> 
> Thank You


The post wasn't aimed at you, so why do you have your knickers all twisted?


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## traceywatts (Jun 2, 2008)

sqnut said:


> The post wasn't aimed at you, so why do you have your knickers all twisted?


I understand that the post wasn't aimed at me. However, in the few years I've been a member of this site, I've seen more personal debates and insults than useful information. I beg for you guys to return to giving useful information. Senseless insults are not the domain of mature adults. I would like to beleive that we can all be mature and keep insults to a minimum. I don't know, are you having a bad day at work/ home? Or, are you always abrasive? Either way, please don't bring it here. I read for hours, nearly every day, to gain a better understanding of sound manipulation and becoming a DIY'er. It's frustrating to try and filter information from an insulting, pointless argument. I am truly disappointed at what this site has become. Please help to make it better.


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## mrplix (Sep 29, 2009)

About the TA thing (sub wave arrives first, then mid, then high). Actually from psychoacoustics point it should be the other way around - first highs, because from the speaker, which closer (with TA) you should get the location cues especially when we are talking about hight cues (have tried it and it works).


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## ErinH (Feb 14, 2007)

quoting myself from elsewhere with an edit...

IMO...


proper *blending* (ie: turning the sub level down to match the midbass output) is detriment to getting the bass 'up front'. This is a case of the weakest link. It seems a lot of people have overdriven subs and the levels aren't well blended. Add to that a resonance issue (discussed below) and you've got problems.
attack (though, different from impact) is key to giving the full effect of an impactful/dynamic system. and getting attack comes from harmonics. I see this chart posted a lot, but for good reason:
Interactive Frequency Chart - Independent Recording Network
if you feel like your 'bass up front' is drifting to the rear with volume, my first suggestion would be to consider the possibility that you're just experiencing *resonance* issues. A stable system will stay put within reason. The drifting or pulling is likely because of a resonance; either enclosure, driver, structure, or acoustical (environment). This will definitely cause you to notice a breakup in your system's staging (ie: 'pull to the doors', 'pull to the trunk'). 


As far as putting a sub in the location to make 'bass up front' just simply consider the issue most cars have with 80hz with in door speakers. Nearly everyone complains about nulls there and it's almost always due to proximity of the door midbass to the listener. Then consider how people talk about repositioning subs in their trunk to get better response. Furthermore, consider the midbass on rear shelf idea. 
Phase. Wavelength. The two correspond. My first thought when I think of subs up front are "what is the trade off". For example, will there be a null at 40hz (or some frequency) because it's closer to you, possibly putting you out of phase there? I don't have experience with this personally, but it's something I often wonder. 

I do not at all think you have to have large midbasses/subs at the front of your car to get an anchored front stage. It just takes experience and time to get your car setup to give this illusion; working with placement and considering wavelength. And, again, I don't feel the issues of resonance can be stressed enough. Resonance is a dead giveaway to a weak link and is almost always the reason why systems aren't stable and anchored with volume. 

Back to the kid.... 

- Erin


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## thehatedguy (May 4, 2007)

There is more to blending than just level matching.


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## ErinH (Feb 14, 2007)

exactly what I meant (check the parenthesis).


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## ncv6coupe (Oct 25, 2009)

So where's the part where guys talk about getting a linear frequency response regardless of volume setting that mimics your baseline setting? I think its safe to say that "impact" and "attack" is a midrange phenemona. Your midrange should "lead the way" in your sound presentation. It should respond to any pulsing as fast as possible and die down equally as fast. Lag in any of those areas and you just shifted the responsibility to who's more inclined for the job and you got phasing and localization problems. I see it hinted that people should start caring more about their midrange enclosures. Everything in life is resonant and has a threshold that you have to pass to get it "worked up." I liken this to the king and queen of destruction "Reflections". Midrange reflections really stomp on high volume ambitions of some with smallish mids because by the time they get good volume to them the much diffracted reflection from the back of the car is rite back up to the listening position and the real mid is about to jump out the basket and producing no more clean output to "lead the way." I also seem to notice(maybe not but it looks that way) some referring to crossovers as magic sound removers, there is soo much blowthrough of midbass through subs and midbass through midrange when you start turning that volume up that generally getting loud and proud boils down to a "I can eq my system better than yours shout fest." Getting more capable drivers is a start. Manipulating your car to keep "quiet" well that's what this thread needs to turn the focus too.


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## sqnut (Dec 24, 2009)

bikinpunk said:


> proper *blending* (ie: turning the sub level down to match the midbass output) is detriment to getting the bass 'up front'. This is a case of the weakest link. It seems a lot of people have overdriven subs and the levels aren't well blended. Add to that a resonance issue (discussed below) and you've got problems.





I have a 12" in a sealed 1.2cuft box in my trunk. The sub is getting a measly 200watts and still the 50-80hz range from the sub is about 6-8 db's louder than from my mids. The SR mids are no slouch. But I figure the sub is just stronger cause its a larger cone. Hence I need to cut the sub a lowish xover, 50hz. Since I don't run a processor, I can't set each driver independently. How I set 50-100hz from the p-880 affects both the sub and the mids. 





thehatedguy said:


> There is more to blending than just level matching.


If you're talking about xover points, slopes, reflections mgt then yes agreed. If its something else then I'm curious.


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## thehatedguy (May 4, 2007)

I dunno...after hearing the real thing (Large sub in front- thanks to Earl Zausmmer and later Scott Buwalda and Steve Head), the illusion is weak compared to the real thing. I've heard it done at low volume levels, but it all has fallen apart at high levels.


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## sqnut (Dec 24, 2009)

I think the large sub upfront would have a ton of install issues to manage as well as limited TA flexibility. 

I feel that subs in the back give better possibilities in setting up a coherent and stable 3-d stage. But I've only heard a couple of front sub installs. Certainly nowhere close to where Earl, Scott or Steve would set it up. So nutshell I just don't know :blush:.


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## Mic10is (Aug 20, 2007)

why would you need to adjust time alignment if the drivers are already in front of you?

Is it often more difficult to install subs in front? Ys obviously the size and space requirements are much more difficult than slappin a box together and move it around in your trunk.

benefits are well worth it IMO.

Ive heard a ton of cars and alot of people brag about how great their up front bass is and its actually pretty apparent once you turn the volume up where the subs are located.


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## quality_sound (Dec 25, 2005)

Mic10is said:


> Thats kind of a vague statement. Please explain what you mean by " do it right"


Everything. Sufficient midbass size, obviously a 5.25" isn't going to get it done, though dual 6's or an 8 will, make sure the sub isn't overbearing, and make sure your seat isn't vibrating giving you tactile cues. It's a **** ton of work but it can be done.


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## quality_sound (Dec 25, 2005)

mattyjman said:


> Id wager that you can't get big impact up front without a decent sized midbass unless your subs are playing into the midwoofer ranges, which i don't know of anyone that is doing that. If the impact doesn't come from sub ranges like lycan said, then if you have a mid that simply can't produce those mid frequencies with any authority then you wont get the up front bass impact. You might get the illusion at low volumes but turn it up to have any fun and it'll drag your ears right to the back of the cabin.
> 
> The reason i started thinking about this is because i recently had two processors that "auto tune" and they came up with varying concepts or results in the midbass range. One was preached as a tool that would get up front bass with any speakers, and the other simply as a good start. The processor that preached up front bass abilities killed my midbasses. At low volumes, it was right. It sounded up front but at any sort of "fun" volume, the bass was clearly coming from the rear. Contrast that with the othe
> r processor and with its reliance on good midbass drivers allowed my system to not only have upfront bass at low volumes but also the impact and illusion at high volumes too



I was giving the members here the benefit of the doubt with regards to proper midbass selection and implementation. As was said earlier, impact is all about midbass. How many people have their midbasses mounted behind them? Almost none. Conversely, how many cars feel like the bass is behind them? Bingo. The problem isn't that we don't have impact, it's that we're getting cues telling us it's behind us. Namely our backs. Adding more and more midbass won't fix the problem since the amount of midbass isn't really the problem in the first place.


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## quality_sound (Dec 25, 2005)

sqnut said:


> Total and utter crap. You just proved once again that you don't have the sound.


I don't know about all that "upper thoracic cavity" stuff, but his comments about deadening your seat are dead on. if you're seat is vibrating you're never going to get that "center of the chest" impact.


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## quality_sound (Dec 25, 2005)

sqnut said:


> May be a bit subjective for you, but here goes.
> 
> *1. Phase Coherence : * 99% of the folks who use TA are aiming for exact same arrival times for sub/mid/high frequencies. Here's what I'm aiming for. I want the sub frequencies to hit me a fraction before the mids hit me together which would hit me a further fraction of of a second before the highs. Hearing the highs (which have all the height cues) last and from a physically higher height, drags the stage up. Measured distance is only a starting point. From there on I delay everything in equal proportion and then break the proportion right at the end. Its all about hearing here.
> 
> ...


I don't think you're underastanding the point of the conversation. We're not talking about the process of getting hard hitting midbass, we're concerned with it not feeling like it's coming from behind us. That, IME, is 100% because the seats are vibrating. You don't need subs in the dash or any other silliness. Design and install your system as you normally would, add mass to your front seat, and you're good. Is it easy? Not even a little. But it works.


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## quality_sound (Dec 25, 2005)

sqnut said:


> I have a 12" in a sealed 1.2cuft box in my trunk. The sub is getting a measly 200watts and still the 50-80hz range from the sub is about 6-8 db's louder than from my mids. The SR mids are no slouch. But I figure the sub is just stronger cause its a larger cone. Hence I need to cut the sub a lowish xover, 50hz. Since I don't run a processor, I can't set each driver independently. How I set 50-100hz from the p-880 affects both the sub and the mids.
> 
> 
> 
> ...



Wait, your sub is too loud and instead of simply turning the gain down on the amp powering it, you decided to move the crossover point???


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## mSaLL150 (Aug 14, 2008)

quality_sound said:


> Everything. Sufficient midbass size, obviously a 5.25" isn't going to get it done, though dual 6's or an 8 will, make sure the sub isn't overbearing, and make sure your seat isn't vibrating giving you tactile cues. It's a **** ton of work but it can be done.


Hey Paul, the seat vibration is the exact problem with my system right now. At lower levels, I've got everything staged up perfectly on the dash. But at higher listening levels, the BMs are shaking my seat and pulling the bass guitar right behind me. The BMs are located under the backseat of my truck and are close to my front seat.

Do I just need a ton more deadener on the floor? Or is this problem somewhat incurable?


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## sqnut (Dec 24, 2009)

Mic10is said:


> why would you need to adjust time alignment if the drivers are already in front of you?
> 
> Is it often more difficult to install subs in front? Ys obviously the size and space requirements are much more difficult than slappin a box together and move it around in your trunk.
> 
> ...


I already admitted that I'm not qualified to comment on sub up front install. However its tough to rid the mindset that eq and TA drivers with lesser PLD would be tougher :blush:. Plus I like to set up my drivers for the crazy sequence mentioned earlier. That's the way I was taught and it works great. Not going to question my mentor nor a concept that seems to work. 

Macleod mentioned that front subs can be made to work in the right circumstances. You're saying the same thing. So accepted.


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## sqnut (Dec 24, 2009)

Oh boy!!!



quality_sound said:


> I don't know about all that "upper thoracic cavity" stuff, but his comments about deadening your seat are dead on. if you're seat is vibrating you're never going to get that "center of the chest" impact.


Agreed. Any vibrations are bad. 



quality_sound said:


> I don't think you're underastanding the point of the conversation. We're not talking about the process of getting hard hitting midbass, we're concerned with it not feeling like it's coming from behind us. *That, IME, is 100% because the seats are vibrating. *You don't need subs in the dash or any other silliness. Design and install your system as you normally would, add mass to your front seat, and you're good. Is it easy? Not even a little. But it works.


BS. In 95% of installs you're hearing the sub from the back cause the xover point is set way too high. Hearing 80-100hz from your sub will locate the sub at the back 10/10. 

Maybe _*you're *_not getting the point. Maybe that's why Mic asked you to explain your vague statement, which you eventually explained with an even vaguer one. BTW depending on the driver, a 5.25" driver is sufficient to get a coherent, stable, 3-d front stage. One where you won't lack for anything.



quality_sound said:


> Wait, your sub is too loud and instead of simply turning the gain down on the amp powering it, you decided to move the crossover point???


ummmmm yes! My gains are already low. Around 9:30 or so. Turning the gains down would turn down _everything from 20hz up_. The problem is the 50-80 range..... it's purely an eq/xover thing.


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## quality_sound (Dec 25, 2005)

mSaLL150 said:


> Hey Paul, the seat vibration is the exact problem with my system right now. At lower levels, I've got everything staged up perfectly on the dash. But at higher listening levels, the BMs are shaking my seat and pulling the bass guitar right behind me. The BMs are located under the backseat of my truck and are close to my front seat.
> 
> Do I just need a ton more deadener on the floor? Or is this problem somewhat incurable?


Marc,
The times I've seen it done it was by adding lead to add mass. I don't know about you, but I'm not adding lead to my seats. TBH, I haven't seen it done in a long time so I'm sure there are other methods.



sqnut said:


> BS. In 95% of installs you're hearing the sub from the back cause the xover point is set way too high. Hearing 80-100hz from your sub will locate the sub at the back 10/10.


I've been doing this a very long time. I know the difference between hearing and feeling. It is not hard to get thebass to sound like it's up front with an 80-100Hz crossover point. If you have to use a 40-50Hz crossover point to keep the bass in front of you then you have other problems. I've never had an issue using 80Hz as my sub to midbass crossover. Zach doesn't have any issues with his 100Hz crossover point either. 



> Maybe _*you're *_not getting the point. Maybe that's why Mic asked you to explain your vague statement, which you eventually explained with an even vaguer one. BTW depending on the driver, a 5.25" driver is sufficient to get a coherent, stable, 3-d front stage. One where you won't lack for anything.


It was not vague. We're not talking about a coherent stage. We're talking about a coherant stage _with lots of volume_. I'd love to see a 5.25" midbass driver that can provide "kick in the chest" midbass at high volumes. It would make a lot of installs easier since we woudln't have to cram in an 8 anymore. At low volumes this is easy since nothing vibrates all that much. Add a lot of volume where the sub starts shaking everything and all of a sudden you have tons of tactile location cues. 



> ummmmm yes! My gains are already low. Around 9:30 or so. Turning the gains down would turn down _everything from 20hz up_. The problem is the 50-80 range..... it's purely an eq/xover thing.


I know it would turn everything down, that was the point. I am curious though, where's the midbass crossed over at?


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## Greg200SE-R (Aug 26, 2005)

You guys can argue about the details all you want. The first significant thing keeping everyone from getting up-front bass is correct time alignment. 

By correct, I mean setting TA manually, with your ears - sitting in your driving position. Using a microphone and software doesn't cut it (I've tried). Setting by ear is the ONLY way to optimal results. The problem is that unless you know what to listen for as you adjust, it's incredibly difficult. 

Up front bass, impact, center imaging and improved frequency response have always been offered by digital TA. The problem has always been how to SET it

I'll post up my method sometime. It's time-consuming, but massively rewarding. It involves methodically listening for the Doppler effect between drivers. Besides the cost of a battery charger (to operate the system with the car off), it only costs you time. 

The fact is, everything the OP is asking for is offered by an active system. And it's available to anyone with such a system, results depending on your patience and how small the TA delay increments are.


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## sqnut (Dec 24, 2009)

quality_sound said:


> I've been doing this a very long time. I know the difference between hearing and *feeling*. It is not hard to get thebass to sound like it's up front with an 80-100Hz crossover point. If you have to use a 40-50Hz crossover point to keep the bass in front of you then you have other problems. I've never had an issue using 80Hz as my sub to midbass crossover. Zach doesn't have any issues with his 100Hz crossover point either.


That's why I have a lower xover point. If my ears locate the sub beyond 70hz, I'm not interested in what Zach has to say....due respects not withstanding. 



quality_sound said:


> It was not vague. I'd love to see a 5.25" midbass driver that can provide "kick in the chest" midbass at high volumes.


The sr 5250 for one. I'm sure there a ton of others. BTW expecting pure sq at 120db is an oxymoron.



quality_sound said:


> I know it would turn everything down, that was the point. I am curious though, where's the midbass crossed over at?


From the sub 20-40hz is lower by 6db from the 50-80hz range. The blend and sub location issue is in the 50-80hz range. Now if I turn down the gains further, yes I might solve the 50-80hz range issue, but I'd loose my 20-40hz range even more. I'd lose a bit of dynamic range. Too big a price to pay IMHO. Sub and mid bass crossed at 50 hz. Sub on a 36db slope and mids on 24db.


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## sqnut (Dec 24, 2009)

Greg200SE-R said:


> You guys can argue about the details all you want. The first significant thing keeping everyone from getting up-front bass is correct time alignment.
> 
> By correct, I mean setting TA manually, with your ears - sitting in your driving position. Using a microphone and software doesn't cut it (I've tried). Setting by ear is the ONLY way to optimal results. The problem is that unless you know what to listen for as you adjust, it's incredibly difficult.
> 
> ...


Boy!!! you need to get into left / right eq control.


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## I800C0LLECT (Jan 26, 2009)

quality_sound said:


> I don't know about all that "upper thoracic cavity" stuff, but his comments about deadening your seat are dead on. if you're seat is vibrating you're never going to get that "center of the chest" impact.


Maybe my install is weird...I can readily move the "chest" impact forward to the hood of my vehicle or towards center console through attenuation of the rear speakers. I definitely understand the "chest" impact due to other installs and other cars I've owned but I've never experienced it in my chest with my current vehicle. My very first install was a set of 320is with kick panels in a Beretta. I definitely had the chest impact with that install but I can't remember the exact setup. I believe cross over point for the sub was ~80hz or 100hz

I will also say that in my current vehicle moving the impact forward on the dash seems to really build the stage presence as if I have a band in front of me. It helps construct the stage it seems(depending on recordings) Does anybody else like that?

My mids are located in the bottom forward location of the door...pointing towards my shins(stock locations). Majority of music plays on the dashboard close to the hood. Maybe pointing the mids helps/hurts the cause?


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## Greg200SE-R (Aug 26, 2005)

sqnut said:


> Boy!!! you need to get into left / right eq control.


I'd have liked to hear that... 9255 was so limited in PEQ bands/channel. But I believe TA should be optimized before any EQ applied... XO points, TA, levels then EQ since each is dependent on the last

BTW, I appreciate your view on time aligning drivers from "slow" to "quick" - bass then mids then highs... time alignment takes this into account


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## sqnut (Dec 24, 2009)

Greg200SE-R said:


> _But I believe TA should be optimized before any EQ applied... XO points, TA, levels then EQ since each is dependent on the las_t


Yes, they are all co-related but no, its not about doing one thing and then tweaking the other. It's about using everything, together. 



Greg200SE-R said:


> BTW, I appreciate your view on time aligning drivers from "slow" to "quick" - bass then mids then highs... time alignment takes this into account


 I don't look as the drivers as slow and quick......but yeah this seems to work.


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## Niebur3 (Jul 11, 2008)

Greg200SE-R said:


> I'll post up my method sometime. It's time-consuming, but massively rewarding. It involves methodically listening for the Doppler effect between drivers. Besides the cost of a battery charger (to operate the system with the car off), it only costs you time.


Would love to read sometime .


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## BigRed (Aug 12, 2007)

Greg200SE-R said:


> You guys can argue about the details all you want. The first significant thing keeping everyone from getting up-front bass is correct time alignment.
> 
> By correct, I mean setting TA manually, with your ears - sitting in your driving position. Using a microphone and software doesn't cut it (I've tried). Setting by ear is the ONLY way to optimal results. The problem is that unless you know what to listen for as you adjust, it's incredibly difficult.
> 
> ...


i tried to explain this in another thread and got royally flamed. good luck with that


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## quality_sound (Dec 25, 2005)

sqnut said:


> That's why I have a lower xover point. If my ears locate the sub beyond 70hz, I'm not interested in what Zach has to say....due respects not withstanding.


Your ears are locating the sub because of other cues (things rattling, vibrations, etc), not the 70Hz crossover point. But if you don't care what others have to say on the subject why are you even here? Apparently you already know everything and don't seem to care what we have to say. I don't know about you, but I'd at least have a listen to what a MECA state champion has to say before I completely dismiss then.



> The sr 5250 for one. I'm sure there a ton of others. BTW expecting pure sq at 120db is an oxymoron.


Only in the midrange/top end. Especially in a car, 120 clean dB in the bottom octaves is doable. 



> From the sub 20-40hz is lower by 6db from the 50-80hz range. The blend and sub location issue is in the 50-80hz range. Now if I turn down the gains further, yes I might solve the 50-80hz range issue, but I'd loose my 20-40hz range even more. I'd lose a bit of dynamic range. Too big a price to pay IMHO. Sub and mid bass crossed at 50 hz. Sub on a 36db slope and mids on 24db.


What kind of car do you drive? I don't know that I've worked on anything but a convertible with the top down that dropped 6 dB in the bottom octave. Even HUGE cars have cabin gain all the way down to 20Hz. Where I'd start is 80Hz/24dB slope on the sub and midbass and eq the peak out. Then the midbass isn't being overdriven trying to do the sub's job. This way everything is stressed less.



I800C0LLECT said:


> Maybe my install is weird...I can readily move the "chest" impact forward to the hood of my vehicle or towards center console through attenuation of the rear speakers. I definitely understand the "chest" impact due to other installs and other cars I've owned but I've never experienced it in my chest with my current vehicle. My very first install was a set of 320is with kick panels in a Beretta. I definitely had the chest impact with that install but I can't remember the exact setup. I believe cross over point for the sub was ~80hz or 100hz


We're talking about different things. It sounds like you're talking about the apparent source point of the bass where we're talking about the physical sensation from the bass. You can't move that because it occurs where you are.


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## sqnut (Dec 24, 2009)

quality_sound said:


> Your ears are locating the sub because of other cues (things rattling, vibrations, etc), not the 70Hz crossover point. But if you don't care what others have to say on the subject why are you even here? Apparently you already know everything and don't seem to care what we have to say. I don't know about you, but I'd at least have a listen to what a MECA state champion has to say before I completely dismiss then.


Have tons of respect for a state champion, world champion and runner up. Thats not the point. You made three specific posts refuting what I said so yes, i probably took that for a bit of attack.  What I forgot to mention is that my posts were from the standpoint of listening with the car parked, engine off. If the back seat was rattling, trust me i'd hear it.



quality_sound said:


> Only in the midrange/top end. Especially in a car, 120 clean dB in the bottom octaves is doable.


The SR 5250 has better mid range than the 6500's that I run. The 6500 are stronger in the mid bass. One big advantage of having a better midrange is better imaging, since most of your imaging cues come from the mid range. Mid bass is a killer. Too much mid bass and it will dull your midrange. Too little mid bass and you'll have a tough time integrating the sub with the mids, with the subs crossed low. Whats the point of a 120db sub stage when your mid bass / mid range can only hit 100? Throws the balance askew. 





quality_sound said:


> What kind of car do you drive? I don't know that I've worked on anything but a convertible with the top down that dropped 6 dB in the bottom octave. Even HUGE cars have cabin gain all the way down to 20Hz. Where I'd start is 80Hz/24dB slope on the sub and midbass and eq the peak out. Then the midbass isn't being overdriven trying to do the sub's job. This way everything is stressed less.


A 3 box variant of the Ford Focus. The Ford Fiesta. Cabin gain is two different things with mids mounted low and all the way forward in your doors and feeding off the floor well vs them mounted 5" below your window. Since you compete, what frequency do you think guys like Mic, Kirk and my bro Macleod cross their subs and mid for finals day?


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## Patrick Bateman (Sep 11, 2006)

mattyjman said:


> Okay, want to generate some thoughtful conversation here on achieving up front bass.
> 
> So, here are my thoughts...
> 
> ...


Autosound 2000 solved this one twenty years ago. Save yourself some heartache and pay the three bucks for their guide to doing this. (Google "david navone autosound2000 upfront bass etc")

In a nutshell, you want to get a few things right:


As Lycan noted, the "impact" of the bass is a lot higher than what you'd think. If you screw up the midbass range, you'll never get the "upfront bass" illusion.
When it comes to subwoofers, second and third harmonic distortion is The Devil. For instance, if a big bass note hits at 40hz, the 2nd harmonic is at 80hz and the third is at 120hz. THERE'S NO ELECTRONIC METHOD TO REMOVE DISTORTION. That's the critical thing to the illusion of upfront bass. YOU CAN'T FIX IT WITH ELECTRONICS. Anyone who tells you otherwise is trying to sell you something, or simply doesn't know better.

Once you have those two points down, you'll start to realize why some systems seem like the bass is up front at low volume, but when you crank it up, it goes to hell. That's subwoofer distortion rearing it's ugly head.

Once you have that figured out, you just pull out the usual tricks to fix it:


Distortion goes up with excursion. Therefor, if you can keep excursion under control, you can keep distortion under control. (There's a reason that Richard Clark used dual 15s. Lots of cone area = low excursion = bass up front.
Infransonic filters can lower distortion dramatically
Unconventional box designs can lower distortion dramatically. Tapped horns, horns, ported boxes and bandpass boxes aren't used half as much as they should be. YES they're difficult, but they're distortion-killers when designed properly. Designed improperly, they can really suck.
Push-pull mounting is free and reduces second harmonic distortion dramatically.
The best way to reduction distortion is to measure it, and deal with it accordingly. I'm always kind of amazed by how difficult it is to pinpoint distortion by ear.


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## ncv6coupe (Oct 25, 2009)

Patrick Bateman said:


> [*]Infransonic filters can lower distortion dramatically
> [*]Unconventional box designs can lower distortion dramatically. Tapped horns, horns, ported boxes and bandpass boxes aren't used half as much as they should be. YES they're difficult, but they're distortion-killers when designed properly. Designed improperly, they can really suck.
> [*]The best way to reduction distortion is to measure it, and deal with it accordingly. I'm always kind of amazed by how difficult it is to pinpoint distortion by ear.
> [/list]


Patrick, welcome back from the abyss, great post as usual! What program and process do you do your distortion measurements with again?


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## Niebur3 (Jul 11, 2008)

sqnut said:


> If the back seat was rattling, trust me i'd hear it.


Please correct me if I am wrong, but "Quality_Sound" is referring to the seat back, not back seat. Your seat back of your front seats can vibrate from the bass and that cue can make the bass seem like it is coming from behind you. If I crossover my door speakers to play all the way to 20hz (sub muted), my seat backs vibrate and make me look behind for the sub (even though the sub is off). I experienced this exact same thing in (will remain nameless - multi time champion in ISACA, USACi and MECA) a car and his subs were actually located upfront. Me and another guy listening kept looking behind us because of seat back vibrations.


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## lycan (Dec 20, 2009)

Patrick Bateman said:


> Autosound 2000 solved this one twenty years ago. Save yourself some heartache and pay the three bucks for their guide to doing this. (Google "david navone autosound2000 upfront bass etc")
> 
> In a nutshell, you want to get a few things right:
> 
> ...


GREAT post, as usual 

One other thing worth noting, is you _really_ need to pay attention to the crossover between subs & midbass. Nothing out of the ordinary, as far as crossovers go ... but it means paying attention to how the two vectors sum at the crossover frequency, in both magnitude & phase (naturally).

I think that poor crossover integration can lead to the following "perception process": somehow "_not right_" becomes "_not front_" in your mind's perception within the small cabin ... and then "_not front_" is finally perceived as "_back_".

But Patrick's points about distortion can not be overstated. If it sounds "right" at low volumes, but "pulls back" at higher volumes, the highest-probability scenario is that your subs are distorting (SDR, or Signal-to-Distortion Ratio, gets worse at higher volumes ... we all know that, right?) and those rapidly increasing harmonics are what's drawing your attention rearward.

It's not hard to put an RTA on the system with JUST the subs playing. Look for a change in the spectral balance as the volume increases.


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## lycan (Dec 20, 2009)

tell ya what ...

*RULE OUT distortion (and panel rattles) first*.

Easy enough to do with a crossover, RTA and volume knob.

I have _yet_ to see anyone who complains about bass being "pulled back" show an RTA at different volume settings, with JUST the subs playing. Not once.


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## ace956 (Aug 28, 2009)

mattyjman said:


> Okay, want to generate some thoughtful conversation here on achieving up front bass.
> 
> So, here are my thoughts...
> 
> ...


mattyjman
have you ever thought about ducting from the woofers to underneath the front seats?
thanks, ace956


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## subwoofery (Nov 9, 2008)

sqnut said:


> I have a 12" in a sealed 1.2cuft box in my trunk. The sub is getting a measly 200watts and still the 50-80hz range from the sub is about 6-8 db's louder than from my mids. The SR mids are no slouch. But I figure the sub is just stronger cause its a larger cone. Hence I need to cut the sub a lowish xover, 50hz. Since I don't run a processor, I can't set each driver independently. How I set 50-100hz from the p-880 affects both the sub and the mids.
> 
> 
> 
> ...


I have 2 solutions to your problem: 
Since your P880's EQ affects both sub and mids, you should try to lower your subwoofer level and use the "bass boost" (yeah I know, the forbidden words) in your amplifier to bring back the 20Hz-40Hz range. That way your subwoofer frequencies will now be ear flat and you'll be able to use the EQ to lighten up your mids. Tried it with an oscope and believe me or not but I did not get any clipped signal. 

Second solution would be... yes you guessed right, to get an EQ. 
What you really need to do for a good bass up front feeling is to have no big hump around 45Hz and a smooth transition from around 63Hz to 160Hz. 
Got that one from Andy and it has literally changed my life... 
Am now back in the _80Hz sub Xover club_ 

I'm using an XBL^2 based driver and that really helps too 

Kelvin 

PS: you should try option 1 and report back


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## quality_sound (Dec 25, 2005)

sqnut said:


> Have tons of respect for a state champion, world champion and runner up. Thats not the point. You made three specific posts refuting what I said so yes, i probably took that for a bit of attack.  What I forgot to mention is that my posts were from the standpoint of listening with the car parked, engine off. If the back seat was rattling, trust me i'd hear it.


I'm talking about listening when parked as well. And it's not the back seat rattling, rather the seat back vibrating. When the seat back vibrates it doesn't matter how good the stage is or how up-front the bass _sounds_ because since your back is feeling it your brain is going to think the bass is behind you. There's no way around that. 



> A 3 box variant of the Ford Focus. The Ford Fiesta. Cabin gain is two different things with mids mounted low and all the way forward in your doors and feeding off the floor well vs them mounted 5" below your window. Since you compete, what frequency do you think guys like Mic, Kirk and my bro Macleod cross their subs and mid for finals day?


Ahh, I like the Fiesta. Great little car. I've owned cars in the size category (Geo Metro, VW Rabbit/Golf, VW GTI, Merkur XR4Ti/Ford Sierra) and they've all had massive cabin gain in the bottom octave. Have you measured the 20-40Hz rolloff?


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## quality_sound (Dec 25, 2005)

Niebur3 said:


> Please correct me if I am wrong, but "Quality_Sound" is referring to the seat back, not back seat. Your seat back of your front seats can vibrate from the bass and that cue can make the bass seem like it is coming from behind you. If I crossover my door speakers to play all the way to 20hz (sub muted), my seat backs vibrate and make me look behind for the sub (even though the sub is off). I experienced this exact same thing in (will remain nameless - multi time champion in ISACA, USACi and MECA) a car and his subs were actually located upfront. Me and another guy listening kept looking behind us because of seat back vibrations.


You got it right, Jerry. That's exactly what I'm talking about.


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## sqnut (Dec 24, 2009)

Niebur3 said:


> Please correct me if I am wrong, but "Quality_Sound" is referring to the seat back, not back seat. Your seat back of your front seats can vibrate from the bass and that cue can make the bass seem like it is coming from behind you. If I crossover my door speakers to play all the way to 20hz (sub muted), my seat backs vibrate and make me look behind for the sub (even though the sub is off). I experienced this exact same thing in (will remain nameless - multi time champion in ISACA, USACi and MECA) a car and his subs were actually located upfront. Me and another guy listening kept looking behind us because of seat back vibrations.


Yes you're right, this is what he said. My bad. But here's the thing. If the seat were vibrating I would feel it. I don't have issues with the sub pulling back. 98% of the time its all upfront even at high volumes 50/63 from my hu. Then again high volume is relative with a xover point of 50hz . 

The issue is on some notes only, the song 'Fingernail Moon' by Annie Lennox has this bass note right at the beginning. This note starts off up front and then about half way through it I get the perception of bass from the rear. It's probably a harmonics issue like Patrick mentioned. Other than the 2% instances like this, 98% of the time there is no issue in keeping frontal presentation.



subwoofery said:


> I have 2 solutions to your problem:
> Since your P880's EQ affects both sub and mids, you should try to lower your subwoofer level and use the "bass boost" (yeah I know, the forbidden words) in your amplifier to bring back the 20Hz-40Hz range. That way your subwoofer frequencies will now be ear flat and you'll be able to use the EQ to lighten up your mids. Tried it with an oscope and believe me or not but I did not get any clipped signal.
> 
> Second solution would be... yes you guessed right, to get an EQ.
> ...


Thanks Kelvin, I agree with your second solution. A processor would allow me to control each driver separately and would help a lot in blending and balancing everything. Not too sure about your 1st solution though. I tried doing this about a year back and could not get the right balance. 

Again, I'm a really happy camper 98% of the time. Maybe I should learn to be content and not get greedy .


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## quality_sound (Dec 25, 2005)

If you're absolutely sure the seat back isn't vibrating (just lean forward a bit and see if the bass moves back up front) then it's either panel resonance (not necessarily rattling) or distortion in the sub.


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## sqnut (Dec 24, 2009)

quality_sound said:


> Have you measured the 20-40Hz rolloff?


To be honest, no. Haven't really measured anything in the last six months or so. I remember doing the test tones when I started off and measuring 20-80 from the sub iirc 50-80hz was louder than the 20-40hz by about 4-5db. It was a while back and I don't have the exact figures.


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## sqnut (Dec 24, 2009)

quality_sound said:


> If you're absolutely sure the seat back isn't vibrating (just lean forward a bit and see if the bass moves back up front) then it's either panel resonance (not necessarily rattling) or distortion in the sub.


Thanks, I will try that on the lennox song and report back


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## sqnut (Dec 24, 2009)

lycan said:


> One other thing worth noting, is you _really_ need to pay attention to the crossover between subs & midbass. Nothing out of the ordinary, as far as crossovers go ... but it means paying attention to how the two vectors sum at the crossover frequency, in both magnitude & phase (naturally).


I'm really interested in what you're saying here. I also feel, that its critical to 'blend' the sub and the mids well in order to pull the sub upfront. To achieve this blend I will typically eq an octave above and below the xover point and use the slopes and TA. I look at the xover point as a baton exchange in a relay race. It should be seamless.


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## sqnut (Dec 24, 2009)

Just looking for some clarifications: 



Patrick Bateman said:


> When it comes to subwoofers, second and third harmonic distortion is The Devil. For instance, if a big bass note hits at 40hz, the 2nd harmonic is at 80hz and the third is at 120hz. THERE'S NO ELECTRONIC METHOD TO REMOVE DISTORTION.


True, but you can use electronics to drive the second and third harmonics beyond the threshold of what you hear. Eg with a sub cut at 50hz on a 36db slope, 80 hz would be about 22db lower and 120 would be over 40db lower. Wouldn't this drive the distortion beyond what you could hear?



Patrick Bateman said:


> Distortion goes up with excursion. Therefor, if you can keep excursion under control, you can keep distortion under control. (There's a reason that Richard Clark used dual 15s. Lots of cone area = low excursion = bass up front.


Would running a 12" on 200 watts with gains set low achieve lower cone excursion? Yes it means the sub isn't pounding but there's still good presence. Not very sure on this one.




Patrick Bateman said:


> Infransonic filters can lower distortion dramatically


So I need to engage the subsonic filter on my mono amp?


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## tornaido_3927 (Nov 23, 2009)

sqnut said:


> True, but you can use electronics to drive the second and third harmonics beyond the threshold of what you hear. Eg with a sub cut at 50hz on a 36db slope, 80 hz would be about 22db lower and 120 would be over 40db lower. Wouldn't this drive the distortion beyond what you could hear?


But then you would be missing out on all that musical bliss of 50hz and over! *It would be far more beneficial to run lower distortion drivers rather than cut fundamental frequenciest just to avoid their harmonics!*
I have my XXLS subs set to around 90-95hz on a 12 or 6db slope (shhh, I'm in the process of installing midbasses for a 3 way, this isn't permanent, but it's the only way to get a bit of bass with 5.5" mids) and all of my bass is up front. When loud my seat back slams, and it feels like it comes from the back, but if I lean forward or even put the seat back back, (lol) and still sit upright, my bass comes from infront of me.
For some reason, I would think that a 50hz crossover point with a 36db slope isn't really "blending".





sqnut said:


> Would running a 12" on 200 watts with gains set low achieve lower cone excursion. Yes it means the sub isn't pounding but there's still great presence.



Completely irrelivant, given we know nothing of the so many variables that are unaccounted for.
I had 600 watts going to each of my 2 subs and I could get them blended and not overpowering, and I'm currently doing the that with the same subs and 300 watts (and I could still make them pound overbearingly with just that).
Low cone excursion as you describe it is not comparitive enough. For example running two of your 12" subs with that same power would mean less cone excursion for the same required SPL, and hence a reduction in distortion.
I hope that's making sense :blush:




sqnut said:


> So I need to engage the subsonic filter on my mono amp?


Maybe you should go flick it on and check if it sounds better


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## sqnut (Dec 24, 2009)

tornaido_3927 said:


> But then you would be missing out on all that musical bliss of 50hz and over! *It would be far more beneficial to run lower distortion drivers rather than cut fundamental frequenciest just to avoid their harmonics!*
> I have my XXLS subs set to around 90-95hz on a 12 or 6db slope (shhh, I'm in the process of installing midbasses for a 3 way, this isn't permanent, but it's the only way to get a bit of bass with 5.5" mids) and all of my bass is up front. When loud my seat back slams, and it feels like it comes from the back, but if I lean forward or even put the seat back back, (lol) and still sit upright, my bass comes from infront of me.
> For some reason, I would think that a 50hz crossover point with a 36db slope isn't really "blending".
> 
> ...


Let's just say we have totally different goals.


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## sqnut (Dec 24, 2009)

cajunner said:


> I think some people are missing the point.


Spot on. The moot question is 'who'.



cajunner said:


> When a subwoofer creates distortion, it doesn't matter where the crossover is set. The speaker is creating unintended sound irrespective of it's input. If it's being driven by a clipping amplifier, distortion comes from the amplifier *in addition to* the distortion inherent in the subwoofer's response. You can have a 36 db slope at 50 hz, but the subwoofer will create second harmonic distortion, at 100 hz. The second and third harmonic distortion is only 20 db below the fundamental sometimes, and at 100 and 150 hz, certainly contains audible distortion when the subwoofer is driven to high SPL.


1. 200 watts to a 450 watts rms sub with the gains on the amp set at 9 o'clock, should not push the sub beyond its linear xmax. 
2. The gains low at the amp and 0 gain at the hu should mean the amp is not clipping.
3. Harmonics are typically rolled off vs the fundamental, add this to the attenuation from the slope, I'll let you figure out how much the harmonics are attenuated. Yes there is distortion but you can't hear the damn thing. Go back to Patricks post. He clearly mentions that its tough to catch distortion in the lower frequency range. 




cajunner said:


> The harder you drive a subwoofer the more distortion it will make, and that means that those second, third, fourth, and fifth order unintended harmonics increase in volume by proportion of clean output to distorted, because you lose power to control the coil the further from the center of the gap it moves. And if the music contains those harmonics as well? Wouldn't the harmonic distortion and the signal combine to exaggerate the amplitude? And what if you have a nodal peak in your vehicle's transfer function? Things aren't just "cut it off at 50 hz" simple.


 I am not overpowering my sub nor clipping from the amp....yes I agree its not as simple at cutting at 50hz, cause you also have to hear (not measure) your way to accurate balance and that can take months.


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## dkh (Apr 2, 2008)

I'd love to personally hear a sub that works crossed around 100hz as I haven't yet - tried it in mine with JBL GTi / FI IB12 subs and have heard a morel ultimo 12 in another car xover'd at 90hz and definitely not working.


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## quality_sound (Dec 25, 2005)

Arc Arc-series, ID IDQs, ID IDMAX, DIYMA R12, SI Mag v4, SI BM MkIII, Alpine Type X, Alpine DDD-drive, Pioneer TS-W12PRS, Kef KAR-series, Alumapro Alchemy, Soundstream SS-10R, SS-12R, SPL-160 (in IB), are all subs I've used or heard crossed over at 100Hz-120Hz that sounded great.


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## dkh (Apr 2, 2008)

quality_sound said:


> Arc Arc-series, ID IDQs, ID IDMAX, DIYMA R12, SI Mag v4, SI BM MkIII, Alpine Type X, Alpine DDD-drive, Pioneer TS-W12PRS, Kef KAR-series, Alumapro Alchemy, Soundstream SS-10R, SS-12R, SPL-160 (in IB), are all subs I've used or heard crossed over at 100Hz-120Hz that sounded great.


Of those, I've owned the ID and IDQ 10 and 12s and they def didn't work anything above 63hz


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## sqnut (Dec 24, 2009)

dkh said:


> Of those, I've owned the ID and IDQ 10 and 12s and they def didn't work anything above 63hz


It's ok. The reference points are very different.


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## Ultimateherts (Nov 13, 2006)

Now I have been reading this thread and researching ideas on my own. I recently want to my IMAX theater which in Massachusetts is owned By Jordan's Furniture. Kick ass cinema the seats have Temperedic memory foam in them and they also have Buttkickers installed. Now I was as skeptical as anybody else, but they can do wonders. I researched the Buttkicker website and they make car audio version that can handle from 500 - 1000 watts. So I am pondering of doing pair running a 500 to each. I know they are not the same as a traditional subwoofer and I know they do not have the cone area of 10" or 12", but they just might do the job!

LINK:

http://www.thebuttkicker.com/downloads/resources/SSW_Insrtuction_Guide.pdf


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## quality_sound (Dec 25, 2005)

dkh said:


> Of those, I've owned the ID and IDQ 10 and 12s and they def didn't work anything above 63hz


All the IDQs I used did just fine up to 100Hz. Application and tuning will make a difference but the driver itself is perfectly capable at 100Hz.


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## quality_sound (Dec 25, 2005)

sqnut said:


> It's ok. The reference points are very different.


Meaning?


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## sqnut (Dec 24, 2009)

The OP's first post mentions 'bass IMPACT'. What he's talking about is chest ponding bass and hence higher db's. That's impact of one kind. You're not going to get this impact without a 80-100hz xover point. 

Then there are others who look at impact as the sense of a live stage across across your windshield. Of course, you're seated a bit off centre at the live venue. 

To get the live feel, you have to combine reproduction of the entire recorded dynamic range, while maintaining tonality with the proper scaling of your stage. By default this means lower decibels and a lower cross over point. 

With sound everything is a trade off. Different people make different choices.
Hence different reference points.


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## Fast1one (Apr 6, 2007)

sqnut said:


> 3. Harmonics are typically rolled off vs the fundamental, add this to the attenuation from the slope, I'll let you figure out how much the harmonics are attenuated. Yes there is distortion but you can't hear the damn thing. Go back to Patricks post. He clearly mentions that its tough to catch distortion in the lower frequency range.


This point clearly indicates that you don't know what you are talking about. 

I'll reiterate again, since clearly you skipped right over this post:

"When it comes to subwoofers, second and third harmonic distortion is The Devil. For instance, if a big bass note hits at 40hz, the 2nd harmonic is at 80hz and the third is at 120hz. THERE'S NO ELECTRONIC METHOD TO REMOVE DISTORTION. That's the critical thing to the illusion of upfront bass. YOU CAN'T FIX IT WITH ELECTRONICS."

Once again, this means that applying a crossover will NOT solve non-linear distortion problems that occur in the crossover's passband. Take your 50 hz lowpass crossover. If the woofer has a large amount of harmonic distortion at a fundamental, say 100hz, than the distortion will be attenuated. HOWEVER, if the woofer has a large amount of harmonic distortion with a fundamental at 40hz, it will NOT be attenuated.


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## sqnut (Dec 24, 2009)

Fast1one said:


> T THERE'S NO ELECTRONIC METHOD TO REMOVE DISTORTION.


There is. lower the damn volume. Read my post again.


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## SSSnake (Mar 8, 2007)

Wow! I'm agreeing with cajunner 

The only way to remove this distortion is with acoustic filtering. Electronic won't cut it. Lowering the power only decreases the levels of the distortion. Will it be enough to prevent locating the sub? Depends on the sub and the install. 

enerally speaking though, reducing the excursion requirements for the sub will help (bigger subs require less excursion for the same volume levels).


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## sqnut (Dec 24, 2009)

cajunner said:


> ..... as you raise volume, ....
> when it was still in linear (not distorted) range, it was inaudible.


Man, I must have been talking Greek and Latin in my last couple of posts . 

I'm talking about lowering the volume and keeping the excursions linear......and the impact derived there off......


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## SSSnake (Mar 8, 2007)

Play a 40hz tone and look at the harmonic distortion products with an RTA. I will guarantee you that you will be surprised. I've done this with some of the finest subs made and there is still significant harmonic distortion.



> Harmonics are typically rolled off vs the fundamental, *add this to the attenuation from the slope *, I'll let you figure out how much the harmonics are attenuated. Yes there is distortion but you can't hear the damn thing. Go back to Patricks post. He clearly mentions that its tough to catch distortion in the lower frequency range.


The bolded section is what we are taking exception too. The electronic crossover, which provides the "slope", will have ZERO effect on these THD products.

I did this test on a sub with XBL^2 and a good rep for being an SQ sub and the THD products were disturbing. I added and acoustic filter and POOF no more sub bass pulling to the rear. Too bad the filter was too big to be permanent.

BTW - Yes up front bass is an illusion


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## sqnut (Dec 24, 2009)

SSSnake said:


> Play a 40hz tone and look at the harmonic distortion products with an RTA. I will guarantee you that you will be surprised. I've done this with some of the finest subs made and there is still significant harmonic distortion.


The fact that you need an RTA to 'hear' that distortion means your ears aren't hearing it. Patrick mentioned distortion is tough to catch in the lower frequencies.





SSSnake said:


> The bolded section is what we are taking exception too. The electronic crossover, which provides the "slope", will have ZERO effect on these THD products.


Yes agreed that square waves don't attenuate over harmonics. Realized that past the edit limit. Keeping the driver within its linear limits would minimize the distortion in the first place.





SSSnake said:


> BTW - Yes up front bass is an illusion


No way Jose!!! It's as real as you and me. It's palpable.


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## SSSnake (Mar 8, 2007)

Alright nut, last attempt.

If you are locating the sub as coming from the rear of the vehicle it is not due to any output or sounds below about 80hz (not a hard limit but you get the picture). This is based upon numerous studies by people much more qualified in audio engineering than myself.

Do we agree on that?

OK, then what IS causing the sound to localized to the rear MUST be sound at greater than 80hz. What contributes to this? Rattles and vibrations in the vehicle, definitely. If those are addressed and the sound still comes from the rear what could be the cause? Excurstion noise is a key culprit as well. If all of these are eliminated then what is most likely the cause? THD from the sub itself. Because these sounds are higher in frequency than the fundamental they are MUCH easier to locate.

BTW - you don't "need the RTA to hear" the noise. You are already hearing it when you locate the sound from the sub as coming from the rear of the car. What you do with the RTA is analyze what you are hearing so that you can reach an educated conclusion about the causes associated with what you hear. This is definitely NOT cut and dry but it will help you in troubleshooting the problem.



> Yes agreed that square waves don't attenuate over harmonics


I'm not sure what you are saying hear as I am NOT talking about square waves or amp clipping or any of the associated phenomena.

I forgot to mention the tacitle location as well. It is completely valid and I am NOT discounting its effects but I believe that you mentioned previously that you did not believe this was the case in your install. If I am mistaken you MUST address this as well to get the ILLUSION of up front bass (and it IS an illusion if the sub is mounted at the rear of the vehicle).

Peace and good luck!


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## ErinH (Feb 14, 2007)

sqnut said:


> The OP's first post mentions 'bass IMPACT'. What he's talking about is chest ponding bass and hence higher db's. That's impact of one kind. *You're not going to get this impact without a 80-100hz xover point. *
> 
> Then there are others who look at impact as the sense of a live stage across across your windshield. Of course, you're seated a bit off centre at the live venue.
> 
> ...


That's simply not true. Plus, it's WAY too much of a generic statement (you have no idea how the environment, enclosure, driver, etc is effecting the sound). As has been stated many times in this thread, impact is more than just SPL. Getting your brain to play along is the hard part (ie: tactile energy).


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## envisionelec (Dec 14, 2005)

Greg200SE-R said:


> You guys can argue about the details all you want. The first significant thing keeping everyone from getting up-front bass is correct time alignment.
> 
> By correct, I mean setting TA manually, with your ears - sitting in your driving position. Using a microphone and software doesn't cut it (I've tried). Setting by ear is the ONLY way to optimal results. The problem is that unless you know what to listen for as you adjust, it's incredibly difficult.
> 
> ...


Exactly.

There are three key points to great "up front" bass.

Low distortion LF reproduction
Time of arrival correction
Relative amplitude equalization

I set my system up with mono tracks playing through the system. This focuses my mind on what's going on with the vehicle's interior. 

First, I set the subwoofer to be just audible on a mono pink noise track. I then played an impulse track with just a simple looped drum beat (kick and snare). Next, I delayed the midbasses (tweeters were muted) until their output corresponded with the leading edge of the subwoofer output. This is critical because time-of-arrival is difficult to control in an automobile. Simultaneously, I turned the subwoofer gain up until the subwoofers were too loud, then backed down a bit. 

The hardest part was getting the soundstage balanced. Mono tracks always sounded diffused because of the L-R differences. Getting them locked in took a lot of crazy EQ settings that had to be refined over and over so the drivers and amplifiers weren't working outside their comfort zones. I found that gentle slopes worked better than steep for the sub-midbass transition and I went with a gentle 6dB/octave at 100Hz, notched a big bite out of the cabin gain (around 60Hz, -20dB Q=1.2 or so), slight rise at 20Hz (+1dB). The system measured well down to about 25Hz. The subwoofers were a quad set of Tangband 6.5" 1139s.

The most surprising aspect was that my commonly held belief that the front midbasses should be very large or heavily EQ'd was basically blown away. I used 6.5" Dayton Reference and crossed them at 65Hz (which was dipped way down by the aforementioned cabin gain removal). I preferred this point due to better amplitude integration, but there was little difference between this and 100Hz as far as the "bass in front" effect.

My processor of choice is still the Behringer DCX-2496.


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## ErinH (Feb 14, 2007)

envisionelec said:


> Exactly.
> 
> There are three key points to great "up front" bass.
> 
> ...


I'd say 4 key points and add resonance: acoustical and mechanical. In fact, I'd place that at the top of the list.


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## envisionelec (Dec 14, 2005)

bikinpunk said:


> I'd say 4 key points and add resonance: acoustical and mechanical. In fact, I'd place that at the top of the list.


Would you agree that this would fall under distortion?


----------



## subwoofery (Nov 9, 2008)

envisionelec said:


> Would you agree that this would fall under distortion?


Resonance of metal due to low frequencies pressure does not fall under distorsion. 

Kelvin


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## sqnut (Dec 24, 2009)

Guys,

I'm describing 'how it sounds'. Most, if not all of you'll are talkig about 'how and what it measures'. You can't get more divergent references than that .

Seriously though:

1. I am not going for loud.

2. I don't have sub localisation issues except on some notes on songs I can count on my fingers. This from about 200 odd cd's that I own and listen to.

3. Yes SSSnake, the sub at the back and its presentation from the front is an illusion. Yes if you hear more than 70hz and above is louder from your sub than your mids, you're in trouble. That is one of the big reasons for a low xover point. I've said that many times. All I'm saying is, that when done right, your senses tell you that its all upfront.

4. Erin, you're quoting my post, focusing on the bolded area and ignoring the other part. In my book Impact _does not equal_ SPL. Sure environments will differ that is why you would have slightly different settings for each environment. As for my general statement, c'mon dude you compete and do well, don't tell me there isn't a subjective side to how you look at, feel and hear the sound .


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## envisionelec (Dec 14, 2005)

subwoofery said:


> Resonance of metal due to low frequencies pressure does not fall under distorsion.
> 
> Kelvin


It's mechanically induced resonance that adds or subtracts from the original signal. IE: distortion.

Moving on...


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## envisionelec (Dec 14, 2005)

sqnut said:


> Guys,
> 
> I'm describing 'how it sounds'. Most, if not all of you'll are talkig about 'how and what it measures'. .


Not all. I did mine all by ear. Then it was measured in another state. It measured quite well, but I didn't really care about that. It _sounded great_.


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## sqnut (Dec 24, 2009)

envisionelec said:


> Not all. I did mine all by ear. Then it was measured in another state. It measured quite well, but I didn't really care about that. It _sounded great_.


I hear you bro. 

From my perspective, yes the car is the crappiest environment in which to reproduce fidelity. Thats a given. 

If I'm in this hobby after accepting this fact, then the objective is where I can take the sound despite the limitations, rather than just focusing on the limitations per se......


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## quality_sound (Dec 25, 2005)

FWIW, I was having a Rsident Evil movie marathon last night and even being able to see my subs (one in each corner) during bass heavy music and effects (particularly in the first one that Marilyn Manson co-scored) the couch vibrating would make it seem like the bass was under, around, or behind me depending on the volume and frequency of the bass and which part of the couch was vibrating.


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## sqnut (Dec 24, 2009)

cajunner said:


> anything that falls under 'room correction' would be distortion, then..
> 
> and something as obvious as panel excitation at higher volume should get attention, whether it's metal or plastic doesn't matter if you are hearing it.
> 
> ...


When I sit and tune, I'm not tuning around the third harmonic of my subs non linear distortion and such. I just tuning for the most lifelike sound while maintaining, appropriate dimensions and toinailty. Actually the two are interlinked. 9/10 when i want to correct something, I will always cut before boosting.


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## sqnut (Dec 24, 2009)

cajunner said:


> do you like having headroom in regards to power from your amps?
> 
> can you hear headroom?


Oh yes I love the headroom when turning my volume up from 44 (Normal listening) to 50 (peak volume). 



cajunner said:


> I'm not saying "boost something to make the sound better"
> 
> I'm saying "boost everything", and fix everything that buzzes at these higher levels than you might normally listen, then go back and be relatively certain you've got 'environment headroom' at your normal levels.


What if I told you that the perception of dynamic range increases with attenuation......


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## sqnut (Dec 24, 2009)

cajunner said:


> what if I told you that you don't understand headroom as used in amplifier terminology?


I'm not setting things up for headroom 'as used in amplifier terminology'. I'm not measuring my way to good sound. I'm hearing my way there.



cajunner said:


> and what if I told you that the perception of dynamic range is just the perception of dynamic range, and attenuation has no bearing on that perception?


Of course it is, with sound a lot is about perception. Attenuating / boosting has a lot to do with it. If you can't deal with that, you need a new hobby.


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## stereo_luver (Oct 30, 2007)

I haven't read all 107 replies but I have this to add for what its worth. My system as tuned to what I have now doesn't draw the listener / ear to any given point in the enviroment unless it is intended by the recording. No single driver dominates the others. My attention isn't drawn to the doors for the midbass, the stage isn't raised to the tweets in the a pillars and the lows don't have me looking behind me. My presence is actually centered in the enviroment and the stage is above the dash and forward of the windshield if you can believe that. BTW I'm running 3-way active up front with a sub added to the rear. So I guess for less confusion my system is a 4-way set-up?

Chuck


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## sqnut (Dec 24, 2009)

stereo_luver said:


> I haven't read all 107 replies but I have this to add for what its worth. My system as tuned to what I have now doesn't draw the listener / ear to any given point in the enviroment unless it is intended by the recording. No single driver dominates the others. My attention isn't drawn to the doors for the midbass, the stage isn't raised to the tweets in the a pillars and the lows don't have me looking behind me. My presence is actually centered in the enviroment and the stage is above the dash and forward of the windshield if you can believe that. BTW I'm running 3-way active up front with a sub added to the rear. So I guess for less confusion my system is a 4-way set-up?
> 
> Chuck


You're doing good, Chuck.


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## stereo_luver (Oct 30, 2007)

sqnut said:


> You're doing good, Chuck.


Thanks. I'm an old fart from old school car audio (51 soon), but have only started taking SQ within my rides seriously for about 2 years. I try to base the system in my truck to mimic my home system. ie my listening enviroment in my home system to be close to the same as my truck. Everything is forward of me with a presence and fullness of the music. Entering my listening room the artwork, as you could call it, are walls lined with room treatments to absorb reflections and the 'sweet spot' is situated to receive the optimum soundwave from the speakers. Trying to do this in the cabin of a truck / car is truely a challenge. Hence the majority of the fun within this hobby. Luckily I have a wife who understands my appreciation for the reproduction of music and lets me, for the most part, carry on with this hobby. She understands I strive for and admire the ability, for me, to hear the bow as it slides across the strings of a violin or the pluck of a pick when it strikes a guitar's strings. My system at home, as my wife says, looks like a compilation of garage sales gear in a stereo rack. But never complains when she can close her eyes and be in THE room where Michael Buble or Sade is singing. A point well made in my defence of the 'garage sale' gear I have in my system!

Chuck


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## 14642 (May 19, 2008)

lycan said:


> GREAT post, as usual
> 
> One other thing worth noting, is you _really_ need to pay attention to the crossover between subs & midbass. Nothing out of the ordinary, as far as crossovers go ... but it means paying attention to how the two vectors sum at the crossover frequency, in both magnitude & phase (naturally).
> 
> ...


Yes, this is correct. 

Time aligning subs is unnecessary, but making the PHASE of the sub complimentary to the midbass at the crossover frequency is necessary. When you do the time alignment thing using your ears, this is precisely what you're doing and precisely why it can't be done by measuring impulse response from the sub. The low pass filter makes the initial arrival impossible to see. 

This is why choosing electrical filters (4th order LR, for example) for their phase alignment considering only their electrical responses is useless. The electrical response DOESN'T MATTER. What does matter is the acoustic response at the listening position and that's the often unstated criterion in crossover design tutorials. 

If you can get the phase right between the sub and the midbass, then the rest of creating the illusion is pretty straightforward:

1. minimize rattles and distortion to the extent possible
2. pay careful attention to the shape of the curve between 60 and 160 HZ when you're equalizing
3. Don't expect the bass to stay in the front when you use your remote bass level control, because turning it up and down affects the acoustic crossover. 

Impact is NOT delivered by your subwoofer and probably not your midbass driver either. For proof of this, download Audacity or some other program that will let you apply low pass filters to an audio file in your PC. Choose a track with great impact and listen to it on headphones through various low pass filters. You'll discover that until there's significant midrange in the signal, there's no impact. 

If you've ever measured impulse responses and thought about them carefully, it'll become clear that the slope of the line that leads to the initial peak defines impact. The slope is steeper as more high frequency is added to the signal. That doesn't mean that tweeters provide impact, but it does mean that without them, the perception of impact is significantly diinished. The screaming sound of a saxophone or a trumpet that so many people try to turn down when they tune because it sounds too "forward" is where you hear impact and tuning for a "laid back" sound that's never aggressive is to tune for a sound that doesn't include any impact.


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## stereo_luver (Oct 30, 2007)

OK...lets go back to the basics and see if this helps the OP

http://www.diymobileaudio.com/forum...cles/33149-mini-tuning-guide-active-user.html

I truely believe if you start here, as basic as it seems, you'll be days ahead in your tuning.

Chuck


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## sqnut (Dec 24, 2009)

cajunner said:


> did I say you had to measure anything?


No, but you and your ilk always allude to how bad things can get when you turn it up. Graphs, numbers, maths and physics follows. You don't get the fact that sq is about turning it down. So tell me that the third harmonic of my subs non linear distortion increases, as I turn the volume down and I'm all ears. Till then......



cajunner said:


> If you give a flippant answer because you know what I'm saying is true and prefer to be contrary, then I have every right to say you don't know what you're talking about.


Maybe I'm just tired of telling you that right brain processing of sound gives better results than that from the left brain.



cajunner said:


> I'd go into the whole headroom spiel but if you've been here as long as you have and can't understand it, I should probably just leave you wallow in your perceptual disbelief.


The forum has enough posts / threads elucidating headroom. We'll spare you the effort. BTW Headroom is the ability to get higher decibels without adding distortion (Again loose definition). Hence 42-50. Your amps ability to fall in line is a given.



cajunner said:


> and, perception of dynamic range, is weird syntactically..is English your second language?


Read Shakespeare, Byron, Keats much? Ever notice the play on linguistic rules?



cajunner said:


> dynamic range, is a range of sounds.


Really???? 



cajunner said:


> by saying "the perception of dynamic range, increases by attenuation" you are either saying "the perception increases" or "the range increases" but you can't put them together and make sense.


Let me try again. "Your appreciation of the dynamic range (roughly) the highest and lowest db's you hear, goes up with attenuation". There is that clear enough for you?



cajunner said:


> you could have said, "the manner in which we perceive dynamic range, changes based on how loud the sounds are"
> 
> to which, I would have to agree.


No cause you're again talking about boosting.


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## ncv6coupe (Oct 25, 2009)

Andy Wehmeyer said:


> *The screaming sound of a saxophone or a trumpet that so many people try to turn down when they tune because it sounds too "forward" is where you hear impact and tuning for a "laid back" sound that's never aggressive is to tune for a sound that doesn't include any impact*.


Andy, I just really Love when you chime in with such controversial information which no one should dare challenge you on.  There was a discussion prior to this statement you just made regarding tuning and it really shook up some folks as to what SQ car audio tuning should be. This quote of yours is a reference to some and kryptonite to others. It left me in a personal sound preference struggle that involves things like sound off competition tuning criteria. Well you know the saying, If you can't beat them join them


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## quality_sound (Dec 25, 2005)

Andy Wehmeyer said:


> Yes, this is correct.
> 
> Time aligning subs is unnecessary, but making the PHASE of the sub complimentary to the midbass at the crossover frequency is necessary.


Isn't that what T/A does? Delays the appropriate drivers so that everything is in acoustic alignment when it gets to you?


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## dkh (Apr 2, 2008)

quality_sound said:


> Isn't that what T/A does? Delays the appropriate drivers so that everything is in acoustic alignment when it gets to you?


Whilst all the rest of your system speakers are on, try changing the t/a on just one midbass - you will get a difference / change in volume of midbass (unless of course, you are correctly dialed in).


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## ncv6coupe (Oct 25, 2009)

quality_sound said:


> Isn't that what T/A does? Delays the appropriate drivers so that everything is in acoustic alignment when it gets to you?


Yes you are right but this is what an equalizer does also(in the bass/midbass region where the wavelengths are huge compared to your head and ears). Bass response is slow and that's not gonna change. This frequency range arguably is the one which excites the most stuff in the car that's why t/a alone is not the cure the dilemna of your more powerful sub having funky frequency response at the front seat of your car. Phase=frequency!


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## lycan (Dec 20, 2009)

quality_sound said:


> Isn't that what T/A does? Delays the appropriate drivers so that everything is in acoustic alignment when it gets to you?


Not necessarily. I understand that this is a point of endless confusion 

It is absolutely true that time alignment can be viewed as nothing more than a linear phase shift (meaning, a phase response that's linear with frequency). Its intended purpose can be viewed, as you've stated, as a tool to make sure drivers are in proper time alignment. BUT ... this does not mean that the drivers will necessarily be in proper phase alignment _at the specific frequency where they crossover_.

How is this possible? If the electrical signals sent to the drivers are time-aligned, taking into consideration the distance from each driver to your ears, doesn't that mean you get proper phase alignment of the acoustic signal at crossover? NOT NECESSARILY ! *The issue is that the crossover circuitry itself, as well as the high-pass characteristics of the driver (Fc, Qtc stuff), all impact the phase (as well as the magnitude, of course) of the acoustic signal we hear. When all of these factors are considered, we come to the inescapable conclusion : time alignment alone does NOT guarantee proper phase alignment at crossover.*

*In other words, the linear phase shift that time alignment gives you is not necessarily the exact phase shift you need for proper phase alignment AT THE SPECIFIC CROSSOVER FREQUENCY.* To convince yourself of this, please consider the "inverse problem" : two drivers can be perfectly time-aligned, radiating from the exact same plane relative to your ears, but yet they may still "blend" poorly at crossover if the crossover filter ... including both magnitude & phase ... is poorly designed.

Interestingly, what matters "more" as frequencies get lower & lower is NOT proper _time alignment_, but rather just making sure you have proper _phase alignment at crossover_. So-called "all-pass" filters can come in handy here, as can proper use of a Linkwitz Transform in tandem with your crossover filter. These tools can, in fact, be more useful in aligning phase _at crossover_ than the tool we know as time alignment.


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## quality_sound (Dec 25, 2005)

ncv6coupe said:


> Yes you are right but this is what an equalizer does also(in the bass/midbass region where the wavelengths are huge compared to your head and ears). Bass response is slow and that's not gonna change. This frequency range arguably is the one which excites the most stuff in the car that's why t/a alone is not the cure the dilemna of your more powerful sub having funky frequency response at the front seat of your car. Phase=frequency!


My question was rhetorical but EQ and T/A are not the same. One works on arrival times and the other changes amplitude. No matter how much you cut or boost a freq. it won't change it's arrival time. You can trick your ear into thinking it's getting there sooner or later with an EQ but the phase will still be off.


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## quality_sound (Dec 25, 2005)

lycan said:


> Not necessarily. I understand that this is a point of endless confusion
> 
> It is absolutely true that time alignment can be viewed as nothing more than a linear phase shift (meaning, a phase response that's linear with frequency). Its intended purpose can be viewed, as you've stated, as a tool to make sure drivers are in proper time alignment. BUT ... this does not mean that the drivers will necessarily be in proper phase alignment _at the specific frequency where they crossover_.
> 
> ...



And this applies to passives only, correct? Since an active crossover won't have a phase shift at the crossover point. 

To compound this, is it more important to have the phase correct at the crossover point or everywhere else? Or will aligning the XO points line everything else up as well?


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## ncv6coupe (Oct 25, 2009)

quality_sound said:


> And this applies to passives only, correct? Since an active crossover won't have a phase shift at the crossover point.


Whoa nelly! An active crossover=a passive crossover(with 12volt power) There IS phase shift(arguably more accurate than passives also) with less susceptibility to crossover point wandering due to a loudspeaker's reactive loads.


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## lycan (Dec 20, 2009)

quality_sound said:


> And this applies to passives only, correct? Since an active crossover won't have a phase shift at the crossover point.
> 
> To compound this, is it more important to have the phase correct at the crossover point or everywhere else? Or will aligning the XO points line everything else up as well?


where do these rumors even _start_?

- An active crossover will have the EXACT same phase shift as a passive crossover.

- It is more important to have phase correct AT THE CROSSOVER FREQUENCY than anywhere else ... for one channel  Sadly, as soon as we introduce another channel (2-channel stereo, multi-channel audio), then phase _between channels_ becomes very important. *Phase is important when any two drivers must "combine" to form a result.*

- By the way, changing the _amplitude_ on your EQ will also change _phase_ of the signal (near the selected center frequency). These EQ filters impact magnitude _and phase_.


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## ErinH (Feb 14, 2007)

Good reads:
Phase angle calculation from time delay and frequency calculate phase difference time of arrival ITD phi phase shift - sengpielaudio

Phase, Time and Distortion in Loudspeakers

EQ, Phase & Time











> All Pass filter response. Note the amplitude response is flat but the phase response is not. This is NOT a minimum phase device.


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## ncv6coupe (Oct 25, 2009)

^^that guy there bikinpunk has some of the smoothest crossver transitions I've ever heard or NOT HEARD!


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## sqnut (Dec 24, 2009)

Andy Wehmeyer said:


> but making the PHASE of the sub complimentary to the midbass at the crossover frequency is necessary. When you do the time alignment thing using your ears, this is precisely what you're doing and precisely why it can't be done by measuring impulse response from the sub. The low pass filter makes the initial arrival impossible to see.





Andy Wehmeyer said:


> 2. pay careful attention to the shape of the curve between 60 and 160 HZ when you're equalizing
> 
> 3. Don't expect the bass to stay in the front when you use your remote bass level control, because turning it up and down affects the acoustic crossover.


I should make that my sig. Maybe i won't get flamed as much . To be honest though, I don't help my cause much when I get worked up. 



Andy Wehmeyer said:


> Impact is NOT delivered by your subwoofer and probably not your midbass driver either. For proof of this, download Audacity or some other program that will let you apply low pass filters to an audio file in your PC. Choose a track with great impact and listen to it on headphones through various low pass filters. You'll discover that until there's significant midrange in the signal, there's no impact.
> 
> That doesn't mean that tweeters provide impact, but it does mean that without them, the perception of impact is significantly diinished.


If you cut your tweets and and only hear your mid bass and sub you will lose a lot of the impact. The resonance off a 125 hz piano note is impact. Cut your tweets and the same note is duller. Impact for me the ability to have lifelike sound across all 10 octaves. 



Andy Wehmeyer said:


> The screaming sound of a saxophone or a trumpet that so many people try to turn down when they tune because it sounds too "forward" is where you hear impact and tuning for a "laid back" sound that's never aggressive is to tune for a sound that doesn't include any impact.


I don't like the 'laid back' sound. It lacks 'bite'. Lifelike sound will have a certain amount of bite to it. A bit subjective here, but I don't know how to describe it in technical terms. :blush:

Tks Andy for a great post.


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## 14642 (May 19, 2008)

ncv6coupe said:


> Andy, I just really Love when you chime in with such controversial information which no one should dare challenge you on.  There was quite a calamity of a thread about a month ago lingering in the 12 volt section that had quite a few people riled up, not that I'm trying to stir that pot again but this is a dilemna that will come up as soon as 2011 competition seasons start up again. I had the chance to experience what that discussion was about from a tuning standpoint after listening to a few cars there and as a past musician and future competitor I can see where I fall in that discussion but we'll see in a few months how this plays out with the guys and the new installs that everyone is working on.


 
Please post a link. I'd like to get riled up again.


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## 14642 (May 19, 2008)

lycan said:


> Not necessarily. I understand that this is a point of endless confusion
> 
> It is absolutely true that time alignment can be viewed as nothing more than a linear phase shift (meaning, a phase response that's linear with frequency). Its intended purpose can be viewed, as you've stated, as a tool to make sure drivers are in proper time alignment. BUT ... this does not mean that the drivers will necessarily be in proper phase alignment _at the specific frequency where they crossover_.
> 
> ...


 
Ding Ding Ding. We have a winner, folks.


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## 14642 (May 19, 2008)

bikinpunk said:


> Good reads:
> Phase angle calculation from time delay and frequency calculate phase difference time of arrival ITD phi phase shift - sengpielaudio
> 
> Phase, Time and Distortion in Loudspeakers
> ...


Yes, these filters can be very useful. In fact, the old "reverse the polarity of one of your midrange drivers for a better image" is a rudimentary attempt at this.


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## quality_sound (Dec 25, 2005)

lycan said:


> where do these rumors even _start_?
> 
> - An active crossover will have the EXACT same phase shift as a passive crossover.


Learn something new every day.



> - It is more important to have phase correct AT THE CROSSOVER FREQUENCY than anywhere else ... for one channel  Sadly, as soon as we introduce another channel (2-channel stereo, multi-channel audio), then phase _between channels_ becomes very important. *Phase is important when any two drivers must "combine" to form a result.*


I knew about the importance of matching phase between channels and drivers in a channel, but why is it most important at the crossover point? Coherancy? Tonal balance?



> - By the way, changing the _amplitude_ on your EQ will also change _phase_ of the signal (near the selected center frequency). These EQ filters impact magnitude _and phase_.


Why only at the center freq? Trying to understand this, would using say, a remote gain on your sub (not a bass boost, but a true remote gain for the sub amp) do the same thing? Why or why not?


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## quality_sound (Dec 25, 2005)

lycan said:


> Not necessarily. I understand that this is a point of endless confusion
> 
> It is absolutely true that time alignment can be viewed as nothing more than a linear phase shift (meaning, a phase response that's linear with frequency). Its intended purpose can be viewed, as you've stated, as a tool to make sure drivers are in proper time alignment. BUT ... this does not mean that the drivers will necessarily be in proper phase alignment _at the specific frequency where they crossover_.
> 
> ...



How would you go about making sure the crossover point is aligned properly? I'm sure there are tools available but I don't have access to anything beyond an RTA and I imagine you can only do so much with your ears, correct?


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## quality_sound (Dec 25, 2005)

Andy Wehmeyer said:


> Ding Ding Ding. We have a winner, folks.


Now the question is, does the MS-8 shoot for alignment at the crossover point or just "generic" T/A based on the impulse arrival times?


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## envisionelec (Dec 14, 2005)

cajunner said:


> anything that falls under 'room correction' would be distortion, then..


Why, yes, it is! But, we need to start with as little "naturally produced" distortion as possible. 



> and something as obvious as panel excitation at higher volume should get attention, whether it's metal or plastic doesn't matter if you are hearing it.
> 
> the idea that the problem exists "only at loud volumes" is a deceptive one, because panel excitation that becomes environmentally audible with high output is also most likely buzzing at lower volumes, but only within the envelope of the music and therefore contained by it.
> 
> ...


Dead on. Someone should invent a passive notch filter so we can strap it to our ears and roam around the cabin looking for rattles.


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## subwoofery (Nov 9, 2008)

sqnut said:


> I should make that my sig. Maybe i won't get flamed as much . To be honest though, I don't help my cause much when I get worked up.





subwoofery said:


> ...Second solution would be... yes you guessed right, to get an EQ.
> What you really need to do for a good bass up front feeling is to have no big hump around 45Hz and a smooth transition from around 63Hz to 160Hz.
> Got that one from Andy and it has literally changed my life...


Seems like I wasn't too far off  

If guyz absolutely need to play with T/A, what I did in 1 car (worked well) was to get a good drum track (stereo drum track from the Emma disc), add 5ms to the front stage (if your subwoofer is the furthest driver from you) and play with the crossover slopes (between midbass and subwoofer) so that bass comes from the passenger's midbass. By adding T/A to the subwoofer, the basslines will run across the dash from the passenger's midbass to the center. 
Add some more until the basslines rises above the dash. Too much and it will sound like it comes from the dash. 
Tried Winmls for impulse but did not like the results. 

Anyone got a pic of what they did to their front seats to make those vibration-free? 

Kelvin


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## quality_sound (Dec 25, 2005)

subwoofery said:


> Anyone got a pic of what they did to their front seats to make those vibration-free?
> 
> Kelvin




RC added a **** ton of lead. Not sure what others did, but weight is really the only way to do it.


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## envisionelec (Dec 14, 2005)

lycan said:


> Interestingly, what matters "more" as frequencies get lower & lower is NOT proper _time alignment_, but rather just making sure you have proper _phase alignment at crossover_. So-called "all-pass" filters can come in handy here, as can proper use of a Linkwitz Transform in tandem with your crossover filter. These tools can, in fact, be more useful in aligning phase _at crossover_ than the tool we know as time alignment.


Super! I found the crossover point and its resultant phase shift the bane of the system's existence. I failed to mention that I did the T/A setup with all filters off and then again with filters on - back and forth until I had a good compromise between localization and phase response. It's a battle; one that I don't have time to win. 

Back in the day when I was young and T/A was still very expensive, I used to balance my front stage by using different order slopes between left and right channels (usually 1st and 3rd). It got me into that wonderful 90° phase shift at the xover point where the ears are less likely to hear full-on cancellation. It was pure luck that it worked in my 4 door Dodge. The downside was huge: power compression shifted the image wildly.


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## lycan (Dec 20, 2009)

quality_sound said:


> I knew about the importance of matching phase between channels and drivers in a channel, but why is it most important at the crossover point? Coherancy? Tonal balance?


No. Phase matters _at the crossover_, because _at the crossover_ we are ADDING the response of TWO drivers. Consider this : i am going to add two numbers : _one_ plus _one_. You probably know the result (since we're not arguing off-topic LOL). What if i INVERT the phase of one of the numbers ... change the phase of one the numbers by 180 degrees. Does the resultant summation change?

*Lesson :* we have to pay attention to the PHASE of two numbers (or acoustic signals) when we ADD them. When do we ADD two acoustic signals? Answer : when one driver is _crossing-over_ to another 

Throw away that word "coherence". It's just ambiguous enough to be meaningless.

So if you conclude the following: in an environment where we might be listening to a single, full-range driver with mono source material (so our whole universe has only a single driver), phase won't matter much at all ... well, that's where you would be RIGHT  But we don't listen like this ... we listen to MULTIPLE drivers, across MULTIPLE channels. When we expect these acoustic signals to "combine" in a certain way, phase matters.

Therefore, in audio, we say that RELATIVE phase matters (between two drivers), but ABSOLUTE phase doesn't matter.

Please work hard to understand this, before i'm quoted partially or wrongly 


> Why only at the center freq? Trying to understand this, would using say, a remote gain on your sub (not a bass boost, but a true remote gain for the sub amp) do the same thing? Why or why not?


Any frequency-dependent magnitude filter will ALSO impact the phase (the minor exceptions aren't worth discussing now). Not just at the "center frequency" of the EQ in isolation, but all around that general neighborhood. Strictly speaking, phase will be impacted _everywhere_ (at all freqs) if you bump an EQ by 1dB at _any_ frequency. But the effect gets smaller, the farther away you get from the selected "center frequency".


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## lycan (Dec 20, 2009)

OK guys ... there's really only one way to understand this concept called "phase". And it's this : one step at a time!

The first step is to understand how we cross one driver over to another in the simple case where the drivers are already time-aligned. Let's just assume, for now, that our two drivers are right next to each other, radiating from the same acoustic plane, the same distance from our ears. So no time alignment is necessary (No ... this does not mean that our discussion will only pertain to this ideal case. It just means we're analyzing a complex problem, by analyzing one component at a time).

Furthermore ... we're listening in mono. So these two drivers ... lets say a midrange and midbass, or midbass and sub ... are the only two drivers in our universe; there's no other channel to worry about for now. (No ... i'm not advocating this as an ultimate "solution". I'm only simplifying a complex topic, by breaking it down into it's basic building blocks).

Let's say the crossover frequency is 200Hz (no, the analysis doesn't collapse if we pick another number). This means that, at 200Hz, each driver will be playing (somewhat), so that the total response of the system will be the ADDITION or COMBINATION of the outputs from these two drivers. This is really only true at the crossover frequency, or very close to it, because as we get farther from the crossover frequency, one driver (in our system of exactly two) will be _dominant_.

Now ... let's say each driver has a MAGNITUDE response that's down -6dB at the crossover frequency of 200Hz. What magnitude will the COMBINED output have :

1. 0 dB (flat)
2. -3dB
3. -infinite dB (deep notch)
4. not enough information given ... the answer could be any of the above, depending on missing information


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## ncv6coupe (Oct 25, 2009)

4, At least tell us if the driver 's polarity will be the same please!


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## masswork (Feb 23, 2009)

4. Polarity?

If both are the same, the answer is 0.
If one polarity is reversed, answer is 3.

Just a quick guess


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## tornaido_3927 (Nov 23, 2009)

Yeah I'd say flat, usually the point of using a crossover is a flat transition! And hence with a butterworth where it's -3db you get a bump at the crossover, if I'm not mistaken.

Does EQ affect phase in the same way that a crossover does? This is the first I have ever heard of EQ changing phase, but it makes sense if an EQ is applied in the same way as a crossover is, but with the difference being one is a shelved rolloff response and the other is a peaking response..?


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## loddie (Jun 23, 2006)

I would guess 1-4 are all possibly correct answers depending on the type of crossover selected (i.e., Linkwitz).

Subscribed. Have a feeling this is about to become the most informative thread on diymobile thanks to Lycan!


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## ncv6coupe (Oct 25, 2009)

^^some of you guys are getting ahead of yourselves. What about power applied to each loudspeaker? That affects their summation too. And crossover type comes into play soon. Lycan is a master of making you answer wrong with his quizzes. Luckily I have picked up on the knowledge and its easier to follow along now.


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## lycan (Dec 20, 2009)

i can feel the love 

Two drivers whose responses, or acoustic outputs, _add_ at 200Hz. But i've only told you the _magnitude_ of each driver's output ... i haven't told you the _phase_. Some of you are clued-in ... "polarity" is NOTHING MORE than a special subset of phase (namely, 180 degrees).

*If the acoustic output signal of each driver is -6dB in amplitude at xover, but the relative phase between the acoustic output signals is 0 degrees (aka "in-phase"), then the resultant summation (or combination) will be 0dB at the xover frequency.

If the acoustic output signal of each driver is -6dB in amplitude at xover, but the relative phase between the acoustic output signals is 90 degrees, then the resultant summation (or combination) will be -3dB at the xover frequency.

If the acoustic output signal of each driver is -6dB in amplitude at xover, but the relative phase between the acoustic output signals is 180 degrees (aka "out-of-phase"), then the resultant summation (or combination) will be -infinite dB (deep notch) at the xover frequency.*

YES, all these combinations are possible ... depending on the crossover filter design (butterworth, bessel, linkwitz-riley, etc). And please note : these two drivers are PERFECTLY time aligned (by physical proximity, according to the original problem statement). *So time alignment, by itself, does NOT guarantee proper acoustic phase alignment between two drivers at crossover.*

We _really_ need to get you guys comfortable with complex arithmetic ... it's really not scary at all, just gotta get used to the notion of imaginary numbers 

Now .. who wants to see how deep this rabbit hole _really_ goes? There's _another_ filter, associated with each & every one of your drivers, _in addition_ to the electronic crossover filter that you apply _electrically_. It's a "built-in" high-pass" filter associated with _every_ driver (in it's piston range) ... even though it's not "electrical" in nature. And, just like the high-pass crossover filter, it not only gives the speaker a high-pass _magnitude response_ ... but this 'built-in" filter gives the driver a similar _phase response_. *If you don't "comprehend" this "built-in" phase response in your crossover design/implementation ... you've only being dealing with half the story.* 

Who can tell us more about this "built-in" high-pass filter ... that's NOT electrical in nature (even though there's GREAT electrical "models" ... or "analogs" ... for it)?


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## tornaido_3927 (Nov 23, 2009)

I think Linkwitzlab.com answers this better than my own words;

_A majority of drivers exhibit second order highpass behavior because they consist of mechanical mass-compliance-damping systems._

Or as I understand it, a surround and spider?


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## lycan (Dec 20, 2009)

tornaido_3927 said:


> I think Linkwitzlab.com answers this better than my own words;
> 
> _A majority of drivers exhibit second order highpass behavior because they consist of mechanical mass-compliance-damping systems._
> 
> Or as I understand it, a surround and spider?


nice work 

but the second-order high-pass response exhibited by drivers is a result of these two _mechanical_ energy-storage elements : mass & suspension (suspension includes surround & spider).

the deal is this: your drivers, all by themselves, have a second-order high-pass filter _built-in_. This built-in filter impacts _magnitude_ and _phase_ near the driver-plus-enclosure's Fc. Ignore it, at your peril 

and yep ... nobody knows how to deal with this built-in high-pass better than Linkwitz  For example ... let's say you want to pay attention to this built-in high-pass ... cuz maybe Fc is kinda near your intended crossover and you realize that it can't be ignored ... but you don't particularly like the response (mag/phase) of this built-in filter. Can you "change" it, or equalize, _electrically_? Why ... yes you can  thank you, Mr. Linkwitz.

And let's face it ... we are ALL operating, or crossing over, our midbass drivers pretty damn close to their Fc's. If you're not "comprehending" this built-in high-pass filter, you ain't never gonna get good integration with your subs (except, by pure trial & error). You don't _need_ a Linkwitz Transform, per se ... a variable all-pass filter can work wonders for phase adjustment near crossover. Maybe Andy will chime in about what the MS8 does between subs and midbass drivers crossed over near Fc ... because by all user accounts, the MS8 is doing something _right_ in this region where subs crossover to midbass.


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## tornaido_3927 (Nov 23, 2009)

Just in case anyone wants to know how Linkwitz is dealing with said built in high pass, check out this page; Active Filters

I am very interested by many things in this article (particularly the 6 and 12db equalization), although I do not understand everything in it just yet :blush:
The pictures are very helpful!


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## lycan (Dec 20, 2009)

... and hopefully, it's becoming apparent by now that proper _phase integration_ between midbass & subs is no small task (particularly if the midbass drivers are crossed over near Fc ... which they almost always are ... and particularly if the midbass enclosures are "ill-defined" ... which they almost always are).

I think it's fair to say the following : we shouldn't conclude that front-mounted subs are "the only way to go", until all this stuff is properly managed  

Fair enough?


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## quality_sound (Dec 25, 2005)

Is there a way to measure this or is it a "by ear" type of thing?


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## I800C0LLECT (Jan 26, 2009)

Wow...reading through this thread sums up my issues over the last year. I've been trying to learn and understand the integration between my mid and sub. All along I've been playing with cross over points and noticing the different cancellations. I'm at a point now (took way too long to get here) where my stage is very coherent and dynamic yet nobody realizes I have 5 speakers playing in the rear of the vehicle; including the sub.

I definitely noticed a while back that T/A did not resolve the issues I thought it would. Matter of fact, I can reach a very nice sound without any TA at all by using the cross over points and some EQ for what I think effects second and third order distortion. Matter of fact, when I focused on what I've been reading about harmonic distortion and ear sensitivity vs. frequency I noticed I was able to make the sound warm, muddy, or tinny.

Now I'm at a point where it seems setting T/A first, then cross over points, and finally EQ is the way to go. I'm really glad some people around here have the mind to put labels to all these interactions and even explain how they effect each other.


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## SSSnake (Mar 8, 2007)

> Maybe Andy will chime in about what the MS8 does between subs and midbass drivers crossed over near Fc ... because by all user accounts, the MS8 is doing something right in this region where subs crossover to midbass.


I want to echo this request. I am having excellent results with the MS8 except in one area... The sub/sub midbass integration. I have done all of the gain settings and actually taken my Rat Shack SPL meter to ensure all channels are at the same output levels. When I go this route the sub is nearly impossible to hear (verified low on RTA). I added the xover in the amp to limit the high freq output of the sub during sweeps and this got the level right where it should be (based on RTA and listening). However, it destroys the sub to midbass integration. Knowing what the black box that is the MS8 is doing in this area would definitely help me know what changes to make to combat this problem.

Andy HEEEELLLLP!

My guess is that the MS8 is is looking at the acoustic response and tailoring the filter the match the target slope you input (that would likely be why it is typically so successful in sub midbass integration). However if that was the case, I'm not sure why after adding my amp xover on the sub channel would cause the midbass integration to go to pot. Unless it is now out of the range of possible adjustments.


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## 14642 (May 19, 2008)

SSSnake said:


> I want to echo this request. I am having excellent results with the MS8 except in one area... The sub/sub midbass integration. I have done all of the gain settings and actually taken my Rat Shack SPL meter to ensure all channels are at the same output levels. When I go this route the sub is nearly impossible to hear (verified low on RTA). I added the xover in the amp to limit the high freq output of the sub during sweeps and this got the level right where it should be (based on RTA and listening). However, it destroys the sub to midbass integration. Knowing what the black box that is the MS8 is doing in this area would definitely help me know what changes to make to combat this problem.
> 
> Andy HEEEELLLLP!
> 
> My guess is that the MS8 is is looking at the acoustic response and tailoring the filter the match the target slope you input (that would likely be why it is typically so successful in sub midbass integration). However if that was the case, I'm not sure why after adding my amp xover on the sub channel would cause the midbass integration to go to pot. Unless it is now out of the range of possible adjustments.


MS-8 uses the measured output of the subwoofer between 50 and 80 Hz to set the level of the sub relative to the front speakers. Then, it equalizes the sub and the fronts separately to meet the target.

When things are right (or within the realm of what MS-8 is designed to do) this works GREAT. When things are not within those constraints, it can't do what it's supposed to do. 

Adding the crossover in the amp to the scenario can be helpful or harmful, depending on what you're using it for. If you're using a tiny sealed box that has a high Q and a high F3, it can be useful in helping MS-8 add some bass below 50Hz. If you're using a bigger box or a vented box, then adding the crossover to MS-8's crossover can make it really difficult for MS-8 to fix the transition. 

Please describe your sub and box in some detail and tell me what crossover points you've tried and I'll be able to steer you in the right direction. Also, you may need to try reversing the polarity of the sub. Give me some details first...


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## SSSnake (Mar 8, 2007)

Andy,

Phone call shortly.

Charles


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## SSSnake (Mar 8, 2007)

Andy,

Left message but hear are the details I think you might be interested in...

Car - 07 Cadillac CTS-V
HU - Stock Bose with amps wired to speaker level ins on the MS8 ( I am using the sub out of the amp into the MS8 but I have tried it without as well - no better - I have also tried changing the phase on the amp sub out into the MS8 without improvement)
Speakers - AE TD6Hs in the kicks, Vifa D26s on the dash, AE IB15s IB in the trunk, stockers in rear doors
Amps - JL Audio HD600 bridged on TD6Hs, JL Audio HD 600 on tweets, JL Audio HD 750 on subs, MS8 amp on rears
Xover freqs - 80 for sub to midbass, 2.5khz for mid to tweet

I have tried phase reversal on mid/midbasses and subs with no better results. Other xover freqs have been tried (between 60 and 100hz) with no better results. I have checked to make sure each mid/midbass is in phase with the other (electrically) by using a battery to verify outward excursion with + voltage.

My thoughts are as follows: With no sub xover on amp engaged the sub to midbass integration is excellent and bass VERY up front but the midbass and subbass is very thin (midbass can be fixed with eq and sub can almost be fixed with gain control). With the sub amp xover engaged (approx 150hz) I get much more subbass output (measured on average of 11db difference) but the sub to mid integration is not good and subbass wanders to rear.

I decided to let others listen and get their thoughts. Erin Hardison and Kirk Proffitt (sp?) both listened and had similar comments. Kirk actually listened as part of a MECA competition and his scoresheet and comments are in line with my thoughts on the SQ (he listened with the sub xover engaged).


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## sqnut (Dec 24, 2009)

SSSnake said:


> With the sub amp xover engaged (approx 150hz) I get much more subbass output (measured on average of 11db difference) but the sub to mid integration is not good and subbass wanders to rear.


A crossover of 150hz, sub to mid is very high. You'd be hard pressed for good integration, since your sub bass would be drowning out your mid bass.


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## lycan (Dec 20, 2009)

sqnut said:


> A crossover of 150hz, sub to mid is very high. You'd be hard pressed for good integration, since your sub bass would be drowning out your mid bass.


that makes no sense.

If you keep _amplitudes_ balanced through crossover, and pay attention to _phase_ at crossover (as discussed) ... one frequency region won't "drown out" the other.


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## sqnut (Dec 24, 2009)

lycan said:


> that makes no sense.
> 
> If you keep _amplitudes_ balanced through crossover, and pay attention to _phase_ at crossover (as discussed) ... one frequency region won't "drown out" the other.


Precisely, thats the theory. Although leveling matching a sub and a mid at 150hz would be a toughie, practically speaking. 

I would add on that you can locate source of sound above about 70hz. So the sub would be located at the rear as SSS mentioned. 

Now, the amplitude balancing is obviously not happening because he mentions that the sub is playing 11db's louder than the mids. Hence the sub is drowning out the mids.


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## lycan (Dec 20, 2009)

sqnut said:


> Precisely, thats the theory. Although leveling matching a sub and a mid at 150hz would be a toughie, practically speaking.
> 
> I would add on that you can locate source of sound above about 70hz. So the sub would be located at the rear as SSS mentioned.
> 
> Now, the amplitude balancing is obviously not happening because he mentions that the sub is playing 11db's louder than the mids. Hence the sub is drowning out the mids.


The only thing difficult about level-matching a sub and a mid at 150Hz, is the typical "car-audio" approach of cranking the sub level until the car rattles, and pain happens. TURN DOWN THE DAMN SUB, until it's level-matched with the mids ... presto!

So yes, I agree that the subs will "drown out the midbass" when you crank the subs to ear-splitting volumes that shake the car three lanes over  But that's not the fault of the crossover frequency chosen ...

You "might" be able to localize at 70Hz (probably not) as far as left/right ... but you certainly can NOT localize 70Hz as far as front/back. Nor can you localize 200Hz as far as front/back ... but you probably CAN localize 200Hz as far as left/right. Pretty much the whole point of this thread ...

All localization techniques used by the human ear/mind are NOT the same. We use different localization techniques for different frequency ranges. Some of these techniques are left/right sensitive, others are front/back sensitive, and still others are up/down sensitive.


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## thehatedguy (May 4, 2007)

So Andy if I read what you said about a sealed box wit High Q and Fs, are you saying the MS-8 could in some way emulate a Linkwitz transform ( Active Filters ). to some degree? I know you can emulate one with 3 bands of parametric.


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## lycan (Dec 20, 2009)

thehatedguy said:


> So Andy if I read what you said about a sealed box wit High Q and Fs, are you saying the MS-8 could in some way emulate a Linkwitz transform ( Active Filters ). to some degree? I know you can emulate one with 3 bands of parametric.


great question ... the other option (maybe used by the MS8) is to just use a more standard _amplitude_ EQ to get the amplitude right at crossover (and elsewhere), and a variable frequency all-pass filter to dial in the _phase_ for seamless crossover. Kinda the "lazy dudes" method for good crossover, without having to bother with a full LT. Should still be pretty damn effective ...


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## sqnut (Dec 24, 2009)

lycan said:


> The only thing difficult about level-matching a sub and a mid at 150Hz, is the typical "car-audio" approach of cranking the sub level until the car rattles, and pain happens. TURN DOWN THE DAMN SUB, until it's level-matched with the mids ... presto!
> 
> So yes, I agree that the subs will "drown out the midbass" when you crank the subs to ear-splitting volumes that shake the car three lanes over  But that's not the fault of the crossover frequency chosen ...


lol, thats not what I was thinking. I was thinking about the fact that 150hz would be much louder from a 10-12" cone than off a 6.5"......even with the sub gains at 0. 



lycan said:


> You "might" be able to localize at 70Hz (probably not) as far as left/right ... but you certainly can NOT localize 70Hz as far as front/back. Nor can you localize 200Hz as far as front/back ... but you probably CAN localize 200Hz as far as left/right. Pretty much the whole point of this thread ...


So with a sub cut at 50hz on a 36db slope, if I cut my mids and tweets (assuming I don't have rattle or other such issues), I would not be able to localize my sub?


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## lycan (Dec 20, 2009)

sqnut said:


> lol, thats not what I was thinking. I was thinking about the fact that 150hz would be much louder from a 10-12" cone than off a 6.5"......even with the sub gains at 0.


You do NOT level match at crossover, by only paying attention to where the gain knob is set! You level match at crossover by _measuring_ the acoustic output of the drivers in question.


> So with a sub cut at 50hz on a 36db slope, if I cut my mids and tweets (assuming I don't have rattle or other such issues), I would not be able to localize my sub?


The answer is that you very likely _could_ localize your sub ... but not because of that 50Hz note that you're asking it to play. If you _can_ localize, it's because the sub is GENERATING a tone at 100Hz, 150Hz, 200Hz, 250Hz, etc. when you ask it to play ONLY 50Hz. These harmonics are called _distortion_, and the crossover slope will have ZERO impact on them ... because they are generated INSIDE the sub, well after the electrical crossover. In other words, the crossover makes sure the sub only "gets" an input signal at 50Hz ... but yet, the poor sub (being an imperfect creature) _still_ creates distortion products much higher in frequency. It's these distortion products that allow you to localize your sub. Increasing the crossover slope won't help this problem at all 

You might also localize "the vicinity" of the sub, because of panel rattles that the sub creates. Similarly, these "rattles" may very well have higher frequency content ... and it's all of this higher-frequency junk which you _can_ localize, front/back.

In short : If your sub created ONLY a 50Hz tone when you asked it to, the answer is NO ... you could NOT localize your sub. It's the higher-frequency distortion & rattle components that allow you to localize. Furthermore, you don't need to have your sub up front, right next to your mids for good integration (in fact, close proximity of drivers is neither a necessary nor a sufficient condition for good integration) ... you just need to pay close attention to both _magnitude_ and _phase_ at crossover, combined with a good understanding of the different localization techniques used by the ear/mind for different frequency ranges.


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## ErinH (Feb 14, 2007)

re: time alignment only effecting phase at a specific frequency.
I understand this. I've seen the effect by doing a comparison in my system with the RTA. Shifting t/a will result in an addition (bump) or subtraction (null) in response at varying frequencies. In fact, for those of you having a hard time wrapping your brain around this concept, run out to your car, crank up the rta. Measure the response. Then change the t/a of ONE driver and measure the response again. See the difference?

Anyway... back to my question... if the response only changes at one frequency how is that we (at least me) don't notice a 'shift' in response throughout the rest of the band for a specific set (left/right) set of drivers?
How about a different explanation:
You are using t/a to center up your image on your midrange only. I can sit in the car and go through various steps in t/a and when I get it 'right' I can hear the image kind of lock in to place. Ie: 0.79ms on the left and 0.89ms on the right gets me a good center image. Why is that we don't notice a smearing of the image if the phase is only affected at one frequency? As if to say we only hear one frequency, because if t/a only effects on frequency, you would at least think that the other frequencies wouldn't necessarily be in phase. Is it because we're dealing with harmonics being affected, too (are they?)?

Furthermore, what about having the same differential between values, but this time your values are 2.69ms for left and 2.78ms right? I notice this especially with tweeters; it doesn't matter the # I use, just as long as the differential between drivers is the same. With the bitone software, as long as my tweeters are 0.08ms apart the phase stays locked. If I go away from that, the phase jumps out. It's a total trip how you can hear the phase of tweeters lock in to place. Push a button, image spreads apart, push a button, image gets a bit better, push a button, image locks together. 
Maybe using a set of drivers isn't the best example as a system is comprised of more than just a left/right set of single drivers, but that should serve well enough to illustrate my question.


PS: Does any of what I just tried to relay make sense? It's pretty tough to put in to words.


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## lycan (Dec 20, 2009)

bikinpunk said:


> re: time alignment only effecting phase at a specific frequency.
> I understand this. I've seen the effect by doing a comparison in my system with the RTA. Shifting t/a will result in an addition (bump) or subtraction (null) in response at varying frequencies. In fact, for those of you having a hard time wrapping your brain around this concept, run out to your car, crank up the rta. Measure the response. Then change the t/a of ONE driver and measure the response again. See the difference?
> 
> Anyway... back to my question... if the response only changes at one frequency how is that we (at least me) don't notice a 'shift' in response throughout the rest of the band for a specific set (left/right) set of drivers?
> ...


When you change time alignment, you change the phase for that driver at ALL frequencies. Time alignment is nothing more than a linear phase shift : 3 degrees at 200 Hz, 6 degrees at 400Hz, 12 degrees at 800Hz (for example).

SO ... it's not at all surprising to see the _interaction_ with _other_ drivers change, at all sorts of different frequencies, when you change time alignment for ONE driver. *As we've discussed, phase changes the summation (or interaction) with OTHER drivers*  These "other drivers" maybe be other drivers on the same channel at crossover, or the other drivers on the _other_ channel.

Now, for the quiz : if you had only ONE driver, playing all alone, in a car (or any environment), would changing the time alignment for this SINGLE driver change the RTA measurement?

Please think carefully : if i play this SINGLE driver 7 seconds later, will the RTA change?


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## ErinH (Feb 14, 2007)

lycan said:


> When you change time alignment, you change the phase for that driver at ALL frequencies. Time alignment is nothing more than a linear phase shift : 3 degrees at 200 Hz, 6 degrees at 400Hz, 12 degrees at 800Hz (for example).
> SO ... it's not at all surprising to see the interaction with other drivers change, at all sorts of different frequencies, when you change time alignment for ONE driver. As we've discussed, phase changes the summation (or interaction) with OTHER drivers These "other drivers" maybe be other drivers on the same channel at crossover, or the other drivers on the other channel.


So, then you are affecting the response at the harmonics? Maybe I'm just having a hard time understanding how the effect of the other frequencies doesn't result in a phase issue at other frequencies. Unless, the "linear" part is just that... the change is linear and affects the relative response the same throughout the band, thus resulting in the driver being 'in phase' throughout the drivers' band. Of course, I'm still talking about only 2 driver's (left/right) relative phase difference. 

I'm just happy you understood what I was asking, because after I typed it up I was beginning to question it myself. 





lycan said:


> Please think carefully : if i play this SINGLE driver 7 seconds later, will the RTA change?


I don't see why anything would change. phase is relative, no?


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## lycan (Dec 20, 2009)

bikinpunk said:


> I don't see why it would change. phase is relative, no?


you're right 

*The MAGNITUDE (or amplitude, SPL) response of a SINGLE driver is NOT impacted by changing it's phase (including time alignment), anywhere.

However ... the MAGNITUDE (or amplitude, SPL) response of TWO or more drivers in combination WILL change, where they are adding or combining at the same frequency, if we change the phase of just one of them. This happens at crossover for drivers on the same channel .... and just about everywhere for drivers on different channels.*


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## lycan (Dec 20, 2009)

When you apply a first-order low-pass filter at 200Hz, you get a _magnitude_ response ... which is a "description" for how the filter will attenuate amplitude at ALL frequencies. 0dB at very low frequencies, -3dB at 200Hz, -6dB at 400Hz, -12dB at 800Hz, etc. Music is nothing more than a combination of all these frequencies, playing at once.

This filter also has a _phase_ response, which is a "description" for how the filter will change phase for ALL frequencies. 0 degrees at low frequencies, 45 degrees at 200Hz, and approaching 90 degrees for very high frequencies.

To answer your question, think of time alignment as *just another filter*. The _magnitude_ response of this filter is 0dB, everywhere (at all frequencies). But the _phase_ response is this : 3.7 degrees for 100Hz, 7.4 degrees for 200Hz, 14.8 degrees for 400Hz, etc (for example).


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## quality_sound (Dec 25, 2005)

Oh jeebus I need to do a LOT of reading.. I'm so confused right now.


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## ErinH (Feb 14, 2007)

I _think_ I understand what you're saying. Basically, when you use t/a you somewhat use it as a you would an EQ. You apply x amount of time alignment, thus canceling out or minimizing response at a certain frequency (we'll call this a fundamental) and ultimately it's harmonics; just as does a hpf/lpf, except the filter effects everything past the initial filter point to a more staunch degree the further you get from the initial filter point.


*crosses fingers I'm in the ballpark*


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## lycan (Dec 20, 2009)

lycan said:


> When you apply a first-order low-pass filter at 200Hz, you get a _magnitude_ response ... which is a "description" for how the filter will attenuate amplitude at ALL frequencies. 0dB at very low frequencies, -3dB at 200Hz, -6dB at 400Hz, -12dB at 800Hz, etc. Music is nothing more than a combination of all these frequencies, playing at once.
> 
> This filter also has a _phase_ response, which is a "description" for how the filter will change phase for ALL frequencies. 0 degrees at low frequencies, 45 degrees at 200Hz, and approaching 90 degrees for very high frequencies.
> 
> To answer your question, think of time alignment as *just another filter*. The _magnitude_ response of this filter is 0dB, everywhere (at all frequencies). But the _phase_ response is this : 3.7 degrees for 100Hz, 7.4 degrees for 200Hz, 14.8 degrees for 400Hz, etc (for example).


Now ... when i _cascade_ time alignment PLUS a crossover, what happens? Simple : magnitude responses (described above) simply ADD (in dB), and phase responses simply ADD (in degrees).

So we see that adding time alignment changes the phase response (or behavior), for ALL frequencies for this driver. 

Conlcusions :

1. There's no guarantee that the cascaded phase response (time alignment plus crossover) is exactly what you need for a seamless crossover, without doing some more work.

2. It's entirely reasonable for the COMBINED _magnitude_ response of this driver, PLUS another, to change as a result of changing the time alignment (and hence, phase response) for a single driver.


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## lycan (Dec 20, 2009)

bikinpunk said:


> I _think_ I understand what you're saying. Basically, when you use t/a you somewhat use it as a you would an EQ. You apply x amount of time alignment, thus canceling out or minimizing response at a certain frequency (we'll call this a fundamental) and ultimately it's harmonics; just as does a hpf/lpf, except the filter effects everything past the initial filter point to a more staunch degree the further you get from the initial filter point.
> 
> 
> *crosses fingers I'm in the ballpark*


it's entirely reasonable, and absolutely correct, to think of time alignment as a specific type of EQ : namely, a _phase_ EQ ... one that has no impact on the amplitude/magnitude of a single driver, but one that _may_ impact how that driver _combines_ with another.

Furthermore, the phase response of this "special phase EQ" is simple to describe : the phase response is _linear_ versus frequency, and the slope is nothing more than the amount of time delay selected by the user.


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## ErinH (Feb 14, 2007)

I guess I should've said you can also use it to increase response at X frequency as well (summation) rather than just assuming one would use it for lowering response.
I've actually noticed a large effect that phase can have simply by adding some t/a to my sub. The impact from behind me went away and the front stage anchored up front much better. I chalked that up as a 'phase eq' effect. 

Now, question... easy one... don't kill me. Is what we're talking about the same thing as constructive and destructive interference or is that only in regards to a different source affecting the system response (ie: road noise or reflections)?


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## lycan (Dec 20, 2009)

It 's informative sometimes to realize that the audio systems we hold near & dear are completely characterized (until distortion starts to rise) by so-called _transfer functions_. These transfer functions are nothing more than two response charts : _magnitude_ versus frequency, and _phase_ versus frequency.

*All audible effects & artifacts show up somewhere in these two plots. And if the supposed "effect" does NOT show up in these two plots, then you won't hear it ... because it doesn't exist.*

Where does the crossover filter show up? In the mag & phase response charts of the drivers we're crossing over.
Where's time alignment show up? In the phase response of the driver we're delaying.
Where's amplifier performance show up? In the magnitude response, with the driver connected.
Where does the cryo-freeze cable treatment show up? It doesn't ... that's why you can't hear it.

These statements are absolutely true ... until we have to consider the nonlinear effects of distortion.

*All linear, time-invariant systems are COMPLETELY & THOROUGHLY characterized ... in both frequency & time domains, for any & all signals of interest ... by their transfer functions, which are nothing more than the magnitude vs. freq and phase vs. freq. relationships.*


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## subwoofery (Nov 9, 2008)

bikinpunk said:


> re: time alignment only effecting phase at a specific frequency.
> I understand this. I've seen the effect by doing a comparison in my system with the RTA. Shifting t/a will result in an addition (bump) or subtraction (null) in response at varying frequencies. In fact, for those of you having a hard time wrapping your brain around this concept, run out to your car, crank up the rta. Measure the response. Then change the t/a of ONE driver and measure the response again. See the difference?
> 
> Anyway... back to my question... if the response only changes at one frequency how is that we (at least me) don't notice a 'shift' in response throughout the rest of the band for a specific set (left/right) set of drivers?
> ...


Sorry if my question is dumb but I read and re-read your post and you apply more T/A to your right side? 

Kelvin


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## lycan (Dec 20, 2009)

bikinpunk said:


> I guess I should've said you can also use it to increase response at X frequency as well (summation) rather than just assuming one would use it for lowering response.
> I've actually noticed a large effect that phase can have simply by adding some t/a to my sub. The impact from behind me went away and the front stage anchored up front much better. I chalked that up as a 'phase eq' effect.
> 
> Now, question... easy one... don't kill me. Is what we're talking about the same thing as constructive and destructive interference or is that only in regards to a different source affecting the system response (ie: road noise or reflections)?


same thing.

"constructive interference" is just a term for a special case of two signals (maybe, from 2 drivers) combining ... namely, combining with something close to a 0-degree phase relationship.

"destructive interference" is just a term for a special case of two signals (maybe, from 2 drivers) combining ... namely, combining with something close to a 180-degree phase relationship.

How about reflections? Well, if we all remember the "image theory of reflections" that i've been advocating over the years, we'll realize that the response of driver-plus-reflection is identical to driver-plus-image, where image is _another driver_ located _behind_ the reflecting plane  so ... the analysis of reflections, including possible constructive & destructive interference patterns ... is NO DIFFERENT than studying how two _different_ drivers _combine_. At any particular frequency of interest (or ... all of them, on a chart with frequency on the x-axis), you need to know both _magnitude_ and _phase_ of the two signals to understand how they combine.


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## ErinH (Feb 14, 2007)

subwoofery said:


> Sorry if my question is dumb but I read and re-read your post and you apply more T/A to your right side?
> 
> Kelvin


the numbers are arbitrary. I was just plucking them out of the air to give an example.


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## T3mpest (Dec 25, 2005)

lycan said:


> Now ... when i _cascade_ time alignment PLUS a crossover, what happens? Simple : magnitude responses (described above) simply ADD (in dB), and phase responses simply ADD (in degrees).
> 
> So we see that adding time alignment changes the phase response (or behavior), for ALL frequencies for this driver.
> 
> ...


I think what BP was trying to ask is this... Since time alignment causes a phase shift that is variable depending on the frequency in question, why does a set amount of time alignment seem to center the sound for all frequencies? For example .4ms of time delay causes different degrees of phase shift depending on the frequency, but .4ms may appear to sum the response at all frequencies. I know in my car if my T/A is correct everything seems to center up, not just a few frequencies.


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## lycan (Dec 20, 2009)

T3mpest said:


> I think what BP was trying to ask is this... Since time alignment causes a phase shift that is variable depending on the frequency in question, why does a set amount of time alignment seem to center the sound for all frequencies? For example .4ms of time delay causes different degrees of phase shift depending on the frequency, but .4ms may appear to sum the response at all frequencies. I know in my car if my T/A is correct everything seems to center up, not just a few frequencies.


might sound like a "circular answer", but it's not : _different_ frequencies need _different_ phase shifts to "interfere constructively", at a fixed point that's _not_ located equidistant from the speakers.


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## lycan (Dec 20, 2009)

The Linkwitz Pluto is designed for fantastic _power response_ ... with the mid driver positioned horizontally, you have no choice but to measure the EXACT same off-axis response, no matter how many degrees "off-axis" you are on the horizontal plane. This has NOTHING to do with acoustics, _per se_, but simple geometry and logic  Hopefully, that should be ridiculously obvious to anyone even glancing at the Pluto. And the tweeter ... mounted "forward" of the mid center line, to minimize diffraction ... will naturally have a great power response, until it starts to beam.

Yes, we tend to be "off-axis" in a car, but the similarity to Pluto pretty much ends there 

And yes, Linkwitz uses active analog electronics ... including an analog approximation to pure time delay, to align the tweet with the mid.

If you want to follow in Linkwitz's steps ... which I highly recommend ... it's not so much a matter of choosing analog electronics or digital electronics. It's a matter of LEARNING about acoustic & electronic principles, and how they play together. For example: how you can use electronics (be it analog, or digital) to _compensate_ for the 2nd-order mechanical/acoustic high-pass filter formed by a driver's moving mass & suspension; how you can use electronics (be it analog, or digital) to _compensate_ for the acoustic low-frequency roll-off of an open baffle speaker. My advice is to spend lots of time on his site, understanding the acoustic principles _first_, then the electrical principles that can _compensate_ or _equalize_. Whether you choose to _implement_ these electronic principles with _analog_ or _digital_ circuitry, then, is just a matter of execution with the easiest or most cost effective tools available to you.

You won't do what Linkwitz has done "a whole lot easier" just because you have a flexible digital processor at your disposal. It didn't take Linkwitz years to develop Pluto because he just couldn't figure out how to do an analog approximation to a pure time delay  There's just no substitute for buckling-down, nose-to-grindstone, and _learning_ ... about acoustics, measurements, transfer functions, etc.


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## 14642 (May 19, 2008)

Arrrrrrrrgh! can't figure out how to link pictures anymore.


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## 14642 (May 19, 2008)

OK, before we get too carried away with phase this and phase that, we should recalibrate a bit. The graph in the link below is the near field response of a factory 6" in the door of a mini cooper. I measured this by holding the mic about 1/4" from the grille. Don't get too carried away trying to figure out why the response isn't super smooth. The narrow notch is most likely not a speaker problem, but none of that matters yet. What's clear is that the response is pretty flat. Keep that in mind as a reference.

http://www.flickr.com/photos/[email protected]/4240691825/

The next one is the same speaker and the same signal measured with the mic in the driver's seat.

http://www.flickr.com/photos/[email protected]/4241476364/

Hmmm...so what the hell creates all the peaks and dips? The difference in the phase of reflected sound and direct sound at the mic position. No amount of dicking around with crossovers or phase will fix this. This is why Richard Clark used to badmouth time alignment--because it can't fix this. What time alignment will fix is the relative phase between drivers that's caused by non-equal path lengths. That's it. 

Of course, it will also change the arrival time of reflections caused by the initial sound by the same amount of delay as the delay of the original sound. Of course, it will not change the arrival time of the sound of the reflections by any other amount or in any other way. We can't voilate the rule of causality no matter how hard we try.

If you listened to a sine sweep, you'd hear much of this, but we don't hear the very narrow peaks and dips very easily with music. There are a couple of ways to make the graph look more like what we hear and the best method is a combination. The first is spatial averaging and the second is spectral averaging. I find that starting with a spatial average and then applying some smoothing is the best way. That's what MS-8 does.

The reason this is pertinent to this discussion is because we're talking about the relative phase between two radiators--speakers for the most part. These reflecting surfaces are also radiators, but they're energized by the speaker--the sound of the speaker causes the reflection. When we have two speakers each driven by a separate amp, one does not cause the other, so we can affect the relationship. This is precisely what happens when you adjust time alignment between two drivers while watching the summed frequency response. 

When you have two speakers playing in a reflective environment, what you hear is the sum of all the reflections and the sum of the two speakers. The trick is to know what you can fix and what you can't fix and the method to use to fix what can be fixed. Since we don't hear the comb filtering with music very easily, I find the best way is to use a spatial average and some smoothing to fix the frequency response of one speaker and its reflections and then the other one and its reflections separately so that the curves match as closely as possible. You have to have separate EQ to do this. Then, play the speakers together. Any dip or peak that's present in the summed signal but not present in the individual signals is caused by the phase relationship between one speaker and all of its reflections and the other speaker and all of its reflections. 

If you've set the time alignment correctly (by compensating for the difference in distance between the mic and each of the two speakers), that's all time alignment will do. For the left and right channel speakers mounted in the doors, time alignment will improve the dip that you see in the summed response around 200Hz or so. That one is causes by the difference in distance. That happens to correspond to a good portion of the vocal range and it's why some people say, "throw one of dem mids out of phase for better imaging". Doing that will fill in the hole at 200 or so and put the left and right channels back in phase at that frequency, but, of course, it will cause an out-of-phase relationship and a hole at a higher frequency. You can't use TA to fix the other peaks and dips. 

If you're still not satisfied after listening and you can't satisfy yourself by simply boosting or cutting with your EQ (remember, high-Q peaks and dips are difficult to hear), then you have to figure out whether the offending peak or dip is caused by a reflection and which reflection. An impulse response and a tape measure can be helpful for this and a working understanding of what an impulse response measurement is and how to use it are required. If you can eliminate the offending reflection by changing the shape of a surface, then you may be able to improve the response that way. Moving the speaker may improve things, but it's like playing whack a mole. Another problem will pop up. Sorting out these reflections is super difficult in a car because the space is so small and there are so many reflections--it's almost impossible to get enough resolution to see the ones at lower frequencies that you can hear and fixing the ones at high frequencies that you will be able to find isn't necessary. If you don't want to do the impulse response thing, you can get in the car and hold a piece of cardboard or something over a bunch of different surfaces until you affect the problem area. Then you can experiment (I think the popular word for "experiment" on this forum is "play") with dfferent shapes and surface treatments to come up with something that has the desired effect. It's not easy, though. You may find that the dashboard is the problem or that the footwell is the wrong shape. Unfortunately, eliminating those features isn't very practical and rebuilding the dashboard for "symmetry" is a really lengthy and expensive experiment that may change the problem but isn't likely to eliminate it. It will get you a bonus point from a judge who doesn't know WTF he's doing, though. 

This is why steep slopes, multichannel audio, more speakers and signal steering is so much better. Steep slopes minimize the interaction of drivers in the same channel playing different frequencies and signal steering minimizes the interaction of drivers playing the same signal to place an image somewhere between the drivers. 

The best fix is to make signals more discreet by using more drivers than to try to minimize phase shift by using shallower slopes and fewer drivers.


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## lycan (Dec 20, 2009)

i largely agree with Andy's post, but i'd "present" the info in a somewhat different way. Let's step back for a moment, and proceed along these lines ... for each fundamental problem we face in car audio, let's identify : the problem itself, how that problem is best _analyzed_, and finally how that problem is best _solved_. No, this short list isn't comprehensive, and this won't be the be-all/end-all post for car audio  but rather just the way my brain tends to organize & process things 

*PROBLEM*: We put drivers in non-optimal _enclosures_. Not usually because we're too stupid to understand the best enclosure, but rather because the environment forces us to.

*analysis*: We can analyze & model the impact on the piston-range behavior of drivers in _any_ enclosure (thanks to Beranek, Small, et al), and understand the impact of Qtc and Fc on the response (both mag & phase) for that particular driver ... _ as well as_ the impact on the crossover to _another_ driver.

*solution* : Simple! EQ  Simple magnitude response EQ, coupled with an all-pass for phase control at crossover for seamless integration. Or, a full-blown Linkwitz Transform (which i _still_ maintain has more utility in a car than a home, simply because of the statement of the problem above).


*PROBLEM* : We are often forced to put drivers in non-optimal _locations_ in the vehicle. For example, we're faced with that pesky problem of having to actually _see_ out of the front windhield 

*analysis* : The best friend i've found for analyzing this problem is understanding how humans localize sound ... ITD, IID stuff. Understand what techniques the ear/mind uses in different frequency ranges, and over what frequency ranges front/back or left/right or up/down matter.

*solution* : Exploit how we localize, in determining how to optimize driver placement in our heavily constrained environment. Often, ideas considered "crazy" by those with the luxury of a less-constrained environment can actually work well : midbass drivers behind you (but still far left, far right), subwoofers just about anywhere, tweeters up high, separated from midrange drivers positioned for minimal PLDs, etc. Good use of _parallel_ time alignment helps here.


*PROBLEM* : we don't sit equidistant from drivers in the left & right channels

*analysis* : not too hard ... at least, for a single listener, where time delay equates to a linear phase shift. For two listeners, or rather "both" listeners, the "combined" analysis typically ... and crudely ... reveals a range of phase inversion in the midrange.

*solution* : time alignment for a single listener. An optimization for "both" front seat listeners typically involves minimizing PLD's, and perhaps ... crudely ... midrange phase inversion. A well-executed center channel can surely help as well  The classic "L+R" is crude (and narrows the stage, unless some techniques are employed to re-widen the stage), and is certainly bested by more sophisticated steering algorithms.


*PROBLEM* : we sit in a small (smaller than Haas), VERY reflective environment.

*analysis* : my favorite analysis technique is that of "image theory". Reflecting boundaries are removed, and replaced by image drivers on the other side. As Andy pointed out, however, you don't have independent control of these image drivers. But the technique allows you to model, and understand, how relative phase differences between real & image drivers create: cabin gain, as well as peaks & valleys in response due to interference.

*solution* : even though one can ... with lots of work ... analyze & model the transfer functions of all these "reflectors", an attempt to EQ all the peaks & valleys will be met with limited success, at best  I think what Andy is proposing, instead, is the solution of _randomizing_ sources, to help "smooth" the response. It's also a difficult technique to master, because localization cues can be easily ruined by haphazard randomization. But if that randomization, in drivers & driver locations, is coupled with intelligent steering algorithms ... then you've got a viable solution.


well, there's more ... maybe later  i think one of the benefits to organizing our thinking this way, is so that we don't get confused and try to apply solution #3 to problems #1 and #4 (for example)


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## ErinH (Feb 14, 2007)

to summarize what has been said in the most crude terms, based on my own experience and studies...
if you're in a null, you're screwed. you can't fix it with dsp. you have to physically move the drivers. the best you can hope for is to use DSP to make a smooth transition between problem areas and non-problem areas.

this is most always directly related to phase, wavelength, and incidence angles. back to constructive/destructive interference. 80hz is a very common null in the car ... guess why. 
Wavelength


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## tornaido_3927 (Nov 23, 2009)




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## s4turn (Jun 17, 2009)

yes
great thread indeed


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## ultimatemj (Jan 15, 2009)

Digging the thread; subscribed~

Thanks to those sharing experience and knowledge!

Based on all that has been discussed, I'm interested to know how you apply these concepts in "priority" for a given vehicle. 

Meaning, do you apply these thoughts when laying things out or during the install or?

In general it seems that we have to come to grips with the fact that we are in a near field highly reflective environment.

So, do you start by reviewing a specific vehicle's space with respect to specific frequencies/ranges, ITDs/IIDs, PLDs/refelections, or? 

Where do you start? What matters most? And what is diminishing returns/waste of time until you have completed/achieved "x".

Thanks and looking forward to reading more on the topic,
M.J.


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## caver50 (Sep 2, 2007)

What does it matter weather or not that it's an illusion or if it actually comes from the front. If you hear it up front and thats your desire, then you have accomplished what you set out to do.

All my sound, sounds like it comes off my dash even though it doesn't, know whatta I mean Vern??

Too many different envirments in too many different vehicles with way too
many different sound systems to completly explain all the varibles. Anyway
I see no reason to look any futher.


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## ncv6coupe (Oct 25, 2009)

cajunner said:


> now, we are hog-tied by the processing, and use of algorithms.
> 
> let's break these bottlenecks, gentlemen!
> 
> I'm going to admit that I don't know which is better in the car, the use of a true 2-way with wideband tweeter, (such as the Pluto concept) or the *4-way plus sub and rears*,


The 2 way sounds very nice especially with mid in front of the seats, only thing is there is limited depth but the You Are There feeling is in tack. I am listening to this right now. The 4 way+rear is what I'm trying to ultimately chase but I have to invest in 2 more DSP channels for the front and not sure if it even matters as I think more about IIR filters and what I'm trying to manually accomplish with 31 band EQ's, I want to get a 6-8 channel car PC built, <<PROBLEM SOLVED
Guess today is car pc information and price hunt day....


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## Greg200SE-R (Aug 26, 2005)

Greg200SE-R said:


> I'll post up my method sometime. It's time-consuming, but massively rewarding. It involves methodically listening for the Doppler effect between drivers. Besides the cost of a battery charger (to operate the system with the car off), it only costs you time.
> 
> 
> Niebur3 said:
> ...


It's been a long while, but I posted my method up in the How-to section. Time alignment by ear. If you're willing to put the time in, up-front bass is just one of many things that will automatically fall into place.

http://www.diymobileaudio.com/forum...gnment-using-only-noise-tracks-your-ears.html


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## HCCA (Apr 6, 2007)

You might want to invest in the Studio Six mic to go with your Iphone RTA app. The Iphone on-board mic is not entirely accurate.

iAudioInterface | Studio Six Digital



cajunner said:


> that's genius!
> 
> now, what are we looking for, exactly?
> 
> ...


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## tjshores (Sep 18, 2010)

In my opinion, up front bass sounds way better and gives a very deferrent impact. The bass hits you in the chest and legs, not in the back of the seat. My sub is the same distance as my mids and highs to my ears. Not everyone has the ability to run front subs thou. I have a F350 crew cab with captain seats. Just took out my center console and installed my 12w7 (custom shaped 1.5cuft sealed box) firing into foot wells under dash. Had to play around with exact distance to dash (has to be within 2" of sweet spot) or bass starts cancelling. When your in the sweet spot, OMG. I've always ran rear subs before, even in this truck, but when I tried the sub up front it was ten times better for sq and stage. Not to mention one sub seems louder than two in the rear when your basically almost sitting on it.


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## sqshoestring (Jun 19, 2007)

Beverly2012 said:


> Big midbass's do help


I'm in this camp to, sure there is a lot of detail and odd issues you can find...but what I see with most systems is 6.5 just can't get it on when you are running that much power on subs like everyone does. Some 6.5 can be really impressive, just saying in general they are not. Way back when I was a kid and didn't care about cutting up my cars or what I put in them...I had a few systems with 6x9 in the front doors and some just using the 'x9 for a mid. Say what you want but they can blow a similar line 6.5 in the weeds for bass/midbass. I see some Euro cars are going to 8" instead of 6.5, I see this as a great choice.

So of course if your weak on the midbass in front everyone lets the sub do it and that causes problems. One poster said cross your subs at 60Hz, I can agree with that and prefer it. You can make it work other ways and lots of people do, but if you cross subs low and make it work its so much easier....IMHO. 

Far as impact I never noticed much, I feel it when its loud I suppose. What I notice is the response and when the midbass is not right its not right. I like the lower car shaking bass better but just the same a smooth response is very important to me and is always my goal for all frequencies. I do have the most issues in the bass to mid region.


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## Patrick Bateman (Sep 11, 2006)

lycan said:


> GREAT post, as usual
> 
> One other thing worth noting, is you _really_ need to pay attention to the crossover between subs & midbass. Nothing out of the ordinary, as far as crossovers go ... but it means paying attention to how the two vectors sum at the crossover frequency, in both magnitude & phase (naturally).
> 
> I think that poor crossover integration can lead to the following "perception process": somehow "_not right_" becomes "_not front_" in your mind's perception within the small cabin ... and then "_not front_" is finally perceived as "_back_".


The more I play around with this stuff, the more I think the REAL problems are in the time domain.

Just for laughs, take a listen to this absolutely craptastic Unity horn I put together:

deadmau5 on unity horn.mp4 - YouTube

The entire crossover is just one capacitor, yet when you listen to the video, you might notice some things:


The percussion is really 'coherent'. For instance, the drum beat has harmonics which go all the way from the bass up to the treble, *and if you don't get these in sync* the sound becomes 'disconnected.' I think this is why a lot of conventional loudspeakers SOUND like speakers. It's that weird artificial disconnect between the drivers.
My amplifier for this experiment is a set of computer speakers, yet despite being woefully underpowered, the sound is fairly 'punchy.' Again, I think a lot of this is because of good integration.
What you're listening to in this video is just one woofer, two midranges, and a single tweeter. The midranges are just 5" in diameter.


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## thehatedguy (May 4, 2007)

Phase and group delay as well IMO...but I don't have a lot of scientific reasoning to support that.

The thing the Unity/Synergy horn does so well is phase. Doesn't it have a better phase response than most single drivers? Or was it impedance?


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## sqshoestring (Jun 19, 2007)

Certainly there is a lot to the pointsource/fullrange driver. I often seem to have better luck in that way by running my mid as high and low as I can. No I have not run a system with a full range yet but would like to try it (w/a 3"). This makes me wonder if adding a midbass in the car will cause more problems with two xover points then, if it is not setup correctly. But it should solve output issues in that range and give better control of FR in my install.


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## Grindcore (Dec 12, 2012)

So what about stopping the seat back vibrating......


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## Grindcore (Dec 12, 2012)

This helped a little bit...had pretty bad vibration through the seat...opened her up packed her with foam and whatever dynamat I had laying around...made it much less noticeable


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## Spyke (Apr 20, 2012)

cajunner said:


> love going back and reading something I've written years ago and saying, "what? you still don't know what you're talking about"
> 
> to myself.


Lol. You just reminded me of a theory I have. I've come to the conclusion that I will *always* be a douche bag. Every time I think about how I was a couple years ago, it's always "God, I was such a douche back then". So, in a couple years i'll think back to now and come to the same conclusion. Unless there's an age limit to it, idk yet.


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## BuickGN (May 29, 2009)

Spyke said:


> Lol. You just reminded me of a theory I have. I've come to the conclusion that I will *always* be a douche bag. Every time I think about how I was a couple years ago, it's always "God, I was such a douche back then". So, in a couple years i'll think back to now and come to the same conclusion. Unless there's an age limit to it, idk yet.


I look at some of my older posts and think WTF was I thinking. Even worse some of my old posts while not as knowledgeable were less arrogant and made more sense, back during a time when a put effort into my posts instead of typing thoughts as they come out of my head (at nearly 100wpm) with no proof reading to make sure they make sense and there's no basic grammar errors. I should know better because too many times I've gotten crucified for one wrong word. Arguing just to argue...... Another relatively new development over the past year or so.


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## sqnut (Dec 24, 2009)

sq from turning it down....lol. 

Circumstances over the last couple of years, forced me to learn that breakout happens when one stops reacting in patterns. Different response for the same stimuli. As creatures of habit that's a tough lesson.


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## 14642 (May 19, 2008)

Years ago when I was an installer at a retail shop in Texas, I was building a ridiculous box for some woofers from a brand that I'll not name. They didn't publish the thiele and small parameters and I was using a box program (that ran on DOS, so this tells you low long ago this was). In any case, he couldn't (by company policy) tell me the parameters (which I thought was ridiculous--and it was) but I was a nasty a-hole to the guy because I was young, thought I knew way more than I knew (that's often part of being young), and was under the impression that a hammer was always the best tool in getting people to do what I wanted (I later married a hammer and that helped me to figure out that a hammer is rarely the best tool). In any case, I was an a-hole and finally got the parameters I needed. I had won the fight and this, of course, provided the kind of positive reinforcement that suggested to me at the time that the hammer was effective.

Year later, I went to work for Harman and was on the receiving end of many of those calls from kids who, like I had years earlier, thought they knew far more than they knew. I recall one that went like this: "I wanna know who is the f-ing moron who designed these f-ing woofers to have f-ing 6-ohm coils. This is the stupidest f-ing b-s&it I've ever seen. Who ever did this should be f-ing fired..." This went on for so long, I thought that this was the only person on Earth who could talk and breathe at the same time.

When he finally took a break, I said, "Sir, are you finished?"

He said, "Yeah...f-ing stupid..."

I said, "I'm the moron who descided that these would be designed this way. I defined the product, worked with one of the industry's best transducer engineers to make sure the woofer performed exactly the way I wanted, and I wrote the owner's manual and all of the technical documentation. Have you read any of it?" 

He was silent.

I said, "How about if I save you the trouble of reading it and I'll just explain."

"OK" he replied. You can probably guess how this ended. 

A few years later, I got a linked in request for a connection from the guy I had berated when I was an installer. He was working at a new company in a position similar to mine. I happily accepted his request and asked for his phone number because I had a story I wanted to tell him. He sent it and I called him. 

I said, "Hey, do you remember years ago a call from a guy who was an a-hole about some thiele and small parameters for a 10" woofer because that guy was building a custom box that your company said wouldn't work?"

"Yes," he replied. " Of course, the woofer would work in that box, but I was required to say what I said. Why do you ask? I'll never forget that call."

I said, "That was me. I'm so sorry. I'll never forget it either."


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## MarkZ (Dec 5, 2005)

Tell us the real reason you designed them to be 6 ohm. Your 8's look like 6's, don't they?


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## Rrrrolla (Nov 13, 2008)

I am debating on tuning my midbasses higher (they are ported) to get about 3db gain at 80hz. The crossover point right now is 60hz and the bass is very much up front. If tuned to 80hz, I will also have to cross them over at 80hz. My question is: Will raising the crossover point 20hz for a full 3db gain at the new crossover point ruin the bass upfront illusion? Ive heard in the past that 60hz is some sort of threshold for the illusion, but when I can get double the output from mids and a flatter response curve, it seems worth a try. If I do it, it will NOT be easy to go back to 60hz, so I will be researching as much as I can before getting out the angle grinder this spring.


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## MarkZ (Dec 5, 2005)

Rrrrolla said:


> I am debating on tuning my midbasses higher (they are ported) to get about 3db gain at 80hz. The crossover point right now is 60hz and the bass is very much up front. If tuned to 80hz, I will also have to cross them over at 80hz. My question is: Will raising the crossover point 20hz for a full 3db gain at the new crossover point ruin the bass upfront illusion? Ive heard in the past that 60hz is some sort of threshold for the illusion, but when I can get double the output from mids and a flatter response curve, it seems worth a try. If I do it, it will NOT be easy to go back to 60hz, so I will be researching as much as I can before getting out the angle grinder this spring.


The answer is in the thread.


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## subwoofery (Nov 9, 2008)

BuickGN said:


> I look at some of my older posts and think WTF was I thinking. Even worse some of my old posts while not as knowledgeable were less arrogant and made more sense, back during a time when a put effort into my posts instead of typing thoughts as they come out of my head (at nearly 100wpm) with no proof reading to make sure they make sense and there's no basic grammar errors. I should know better because too many times I've gotten crucified for one wrong word. Arguing just to argue...... Another relatively new development over the past year or so.


Sig worthy... Where's Chad???  

Kelvin


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## Rrrrolla (Nov 13, 2008)

cajunner said:


> 3 db is not double the output.


3db more spl is not double the spl? I know it doesnt SOUND twice as loud because the sensitivity of our ears are not linear, but it IS twice the spl isn't it? Could you clarify this for me please? We use db's as referenced to 1mW all the time here at work, and I can show you mathematically that 3dbm is 2mW, and 10dm is 10mW, and so on... Is there something unique about spl that it doesnt follow the same rule?


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## drop1 (Jul 26, 2015)

I wanted to resurrect this thread as I think many members on the board have a better understanding of this now years later.


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