# Pro woofers VS High xmax subwoofers=tight,punchy VS boomy,loose



## Steak (Mar 16, 2006)

So I googled efficiency vs xmax, and came across a very interesting thread in another forum, just thought I would share...

Pro woofers VS High xmax subwoofers=tight,punchy VS boomy,loose - AVS Forum

I only read up to about page 4. WAAAAAAAY over my head, but very interesting. Anyways, its way past my bed time...


----------



## pyr0maniac (Jan 25, 2009)

Good find


----------



## aztec1 (Jun 13, 2008)

AHA!! So sealed boxes DO sound better!


----------



## thehatedguy (May 4, 2007)

"tight punchy" bass is the midbass characteristic of the sub.


----------



## SSSnake (Mar 8, 2007)

> "tight punchy" bass is the midbass characteristic of the sub.


Ding, ding, ding; we have a winner!


----------



## mattyjman (Aug 6, 2009)

anyone wanna provide the cliff notes? i am new to this, and this post especially is miles over my head...


----------



## Steak (Mar 16, 2006)

mattyjman said:


> anyone wanna provide the cliff notes? i am new to this, and this post especially is miles over my head...


Im a bit of a newb myself, but I can try to help you understand. Hopefully someone else will help me as well 

Pro audio woofers tend to be very efficient and have low excursion. This usually means that they excel at freqs 50 - 150Hz (usually much higher as well, but we are discussing bass at this point). They tend to be not very good at producing 'real sub bass', ie. 20 - 50 Hz. With this in mind, some people relate their sound signature as quick, with good kick drums, and some times relate this to SQ.

On the other hand, woofers with very large xmax tend to be inneficient, and excel at playing 20-50Hz, but do not usually play much above that. Since this type of bass is 'deeper' some people relate this to boomier bass, ie less snappy, and some feel that they dont have the 'kick' or quick response required in a SQ sub.

So the discussion goes on to several points. What is SQ? What does a proper kick drum sound like? What should a sub play - should the FR be flat or not? Can different subs be eq'ed to sound alike? Do higher freqs (1k-8K) affect our interpretation of a kick drum? Do crossover points play a role? What about phase/time alignment? Etc, etc etc...


----------



## Steak (Mar 16, 2006)

thehatedguy said:


> "tight punchy" bass is the midbass characteristic of the sub.


For instance, old school IDW subs tend to be very liked by the SQ crowd. Weren't these essentially prosound woofers?


----------



## chad (Jun 30, 2005)

In pro audio there's not as much concern int he sub 40 range as long as it gets there good and loud. remember we are not filling cars, we are filling venues. I personally like a sub system to go down to 35 cycles without damage and I will put a HPF there to keep me safe. if they go to 30 I'm stoked.... I'll often still HPF the rig at 35......

It takes a ****ton of power to make that last little bit, power I really don't want to waste, and even IF I wanted to go to 20 cycles I'd have a hell of a time assuring equal coverage. yes, it would be cool in theory but often times it's just not practical. 

It comes right down to this... what IS the difference between 20 and 30 cycles? Not a whole hell of a lot, and before you go "well my car........" type of mouth words, remember this. Your car ain't excelling to 20, it's going LOWER into infrasonics and this is being aided by the closed cabin characteristics.... With a big fuggin hump.... you guessed it... 30 -40 cycles... right where most pro sub systems are tuned


----------



## Steak (Mar 16, 2006)

chad said:


> In pro audio there's not as much concern int he sub 40 range as long as it gets there good and loud. remember we are not filling cars, we are filling venues. I personally like a sub system to go down to 35 cycles without damage and I will put a HPF there to keep me safe. if they go to 30 I'm stoked.... I'll often still HPF the rig at 35......
> 
> It takes a ****ton of power to make that last little bit, power I really don't want to waste, and even IF I wanted to go to 20 cycles I'd have a hell of a time assuring equal coverage. yes, it would be cool in theory but often times it's just not practical.
> 
> It comes right down to this... what IS the difference between 20 and 30 cycles? Not a whole hell of a lot, and before you go "well my car........" type of mouth words, remember this. Your car ain't excelling to 20, it's going LOWER into infrasonics and this is being aided by the closed cabin characteristics.... With a big fuggin hump.... you guessed it... 30 -40 cycles... right where most pro sub systems are tuned



That makes sense. With cabin gain a prosound woofer gets help down low, which usually doesnt happen in home/outdoors. So, from your point of view, do you prefer these subs in a car - What is your take on the title of this thread?


----------



## Oliver (Jun 25, 2007)

quote>
Infrasound is sound that is lower in frequency than 20 cycles per second, the normal limit of human hearing. Hearing becomes gradually less sensitive as frequency decreases, so for humans to perceive infrasound, the sound pressure must be sufficiently high. The ear is the primary organ for sensing infrasound, but at higher levels it is possible to feel infrasound vibrations in various parts of the body.

The study of such sound waves is sometimes referred to as infrasonics, covering *sounds beneath 20 Hz down to 0.001 Hz.* This frequency range is utilized for monitoring earthquakes, charting rock and petroleum formations below the earth, and also in ballistocardiography and seismocardiography to study the mechanics of the heart. *Infrasound is characterized by an ability to cover long distances and get around obstacles with little dissipation.*
quote>


----------



## Steak (Mar 16, 2006)

a$$hole said:


> quote>
> Infrasound is sound that is lower in frequency than 20 cycles per second, the normal limit of human hearing. Hearing becomes gradually less sensitive as frequency decreases, so for humans to perceive infrasound, the sound pressure must be sufficiently high. The ear is the primary organ for sensing infrasound, but at higher levels it is possible to feel infrasound vibrations in various parts of the body.
> 
> The study of such sound waves is sometimes referred to as infrasonics, covering *sounds beneath 20 Hz down to 0.001 Hz.* This frequency range is utilized for monitoring earthquakes, charting rock and petroleum formations below the earth, and also in ballistocardiography and seismocardiography to study the mechanics of the heart. *Infrasound is characterized by an ability to cover long distances and get around obstacles with little dissipation.*
> quote>


Thanks for the Wiki quote, but what is your take on the subject?


----------



## chad (Jun 30, 2005)

I don't really PREFER them because they need a HUGE box to make them operate as well as or worse than a typically available driver intended for the car audio market. 

IF I were competing in a class where I was limited in power (like the old-skool under 50 watt class) and minitrucks with toppers were still the rage, I'd be all over it. The sensitivity is king.

I don't know what to think about the thread because I despise the words "tight" and "boomy," because as mentioned before, this characteristic is relative to he driver's upper frequency performance.


----------



## Wheres The Butta (Jun 6, 2009)

So a higher xmax woofer will reproduce the low rumbly stuff better, and thus would make for a better H/T subwoofer? For *most* music, I don't think the reproduction will suffer much with the elimination of sub 35hz freq, but other media might suffer a bit.


----------



## aztec1 (Jun 13, 2008)

There's also some interesting talk about how vents may affect sound quality that I found very interesting:



Tom Danley said:


> This , particularly in smaller rooms, gives a sealed box woofer the potential of having a deeper more extended in room response compared to say a vented box that rolls off at 24dB per octave .
> On the other hand, vlf response to me adds a sensation of weight and size, not punch.
> 
> A vented box uses a phase inverter, it uses the radiation from the back side driving a Helmholtz resonator which acts as the phase inverter.
> ...


I take this to mean that in a small environment like a vehicle, a sealed box has the potential to sound better because of a smoother rolloff with no phase change from a vent. Now I'm far from a "golden ear", but have never preferred vented boxes in a vehicle...especially a truck where the sub is in-cabin. Does this sound like a reasonable explanation for this or am I misinterpreting what's being said?


----------



## chad (Jun 30, 2005)

You ear better be DAMN golden to hear that delay that's incremental as frequency lowers, at that low of a frequency...... I could see this as a possibility with rather high tuning but for low tunings, even though the delay is longer...... don't see it, the mind/ear does not work that way. 

NOW, if you are integrating say a vented mid/hi or even a fullrange vented rig to a VLF driver I can see the marriage of the two delay responses giving you headaches.


----------



## aztec1 (Jun 13, 2008)

I thought the ear was more sensitive to phase changes at lower frequencies? Maybe it's just me, I can sure tell a difference switching polarity on a sub but on a tweeter it's much more difficult.


----------



## Steak (Mar 16, 2006)

Well what I can gather from that post from Mr Danley are basically two things:

1. As it is well known, a sealed box rolls of less quickly than a vented box. 12dB per octave vs 24dB per octave. Thus the sealed box should play a 'flatter', wider bandwiidth than the vented design.

==> For this, I would argue that cabin gain in a vehicle might help the vented box design, as noted by Chad. Maybe this can help close the gap in the bandwidth response between sealed/vented.


2. Delay of half a wavelength at around the low corner and above (I believe this is the Fb, not sure though), due to the vent acting as a phase inverter, thus reducing perceived impact and punchiness.

==> This I was not aware of. I wonder if it could be tackled with time aligment of something


To answer your post, I guess you are on the right track. A sealed box seems to bring to the table less compromises and complications, at the expense of decreased efficiency?


----------



## WRX/Z28 (Feb 21, 2008)

I've seen chad mention before that he doesn't follow why people cross their subs over so low. (65-70hz) 

I do this myself mostly because I feel that as the sub plays higher, my ear is drawn backwards more. The higher the sub plays, the more easily localized it is. 

Some will argue that the localization cues are due to rattles/resonances in the rear of the car. In my experience, I don't beleive this is always the case. 

The higher the sub plays, the "boomier" it sounds to me in most cases. Also, the higher the sub plays, the more it seems to intrude on what the front speakers are playing midbass wise. Granted, the phase relationship plays a part in this, but even trying to account for this, I find time and time again that too high of a crossover causes most woofers to exhibit nasty artifacts, and to draw my ears backwards. 

I find it weird that my experiences have been exactly the opposite of what most are saying. Maybe I just need to experiment with time alignment and phase relationships some more. Maybe a sub crossed over at say 90-100hz, and carefully dialed in with a front stage could sound good to me, but I haven't been able to accomplish this as of yet. 

My feeling is that the better solution for midbass response, and a "tight" sounding sub, is a strong front midbass driver that can dig deep. Properly deadened doors, and careful blending using phase adjustment, and Time alignment are key. This from my experience anyway...


----------



## Steak (Mar 16, 2006)

Steak said:


> Im a bit of a newb myself, but I can try to help you understand. Hopefully someone else will help me as well
> 
> Pro audio woofers tend to be very efficient and have low excursion. This usually means that they excel at freqs 50 - 150Hz (usually much higher as well, but we are discussing bass at this point). They tend to be not very good at producing 'real sub bass', ie. 20 - 50 Hz. With this in mind, some people relate their sound signature as quick, with good kick drums, and some times relate this to SQ.
> 
> ...



I guess the last post by a member on the AVS Forum pretty much sums it up:



> assuming no significant externalities, such as a resonant room or a poorly designed enclosure, the whole debate over mid-bass punch seems to come down to distortion and efficiency (sensitivity)?
> 
> if that is right and assuming that the drivers we are discussing have low distortion (demodulating rings and so forth), the only thing left to sort the drivers is efficiency (sensitivity).
> 
> ...


Lots of interesting subjects and discussions in the middle though


----------



## 94VG30DE (Nov 28, 2007)

chad said:


> NOW, if you are integrating say a vented mid/hi or even a fullrange vented rig to a VLF driver I can see the marriage of the two delay responses giving you headaches.


This is actually one of the problems I'm having in my car right now, because there is such a big gap between my vented 4" mid and my vented 10" sub that the steep roll-off on both drivers is causing frustrations in tone as well as timing.


----------



## Steak (Mar 16, 2006)

I suppose that is why THG runs a couple of sealed/IB IDW15s


----------



## chad (Jun 30, 2005)

WRX/Z28 said:


> I've seen chad mention before that he doesn't follow why people cross their subs over so low. (65-70hz)


I can tolerate 65-70, it's the people that swear by 50 cycles and lower is where I wonder. Here's a question.... do you run a sealed or vented alignment?


----------



## Steak (Mar 16, 2006)

WRX/Z28 said:


> I've seen chad mention before that he doesn't follow why people cross their subs over so low. (65-70hz)
> 
> I do this myself mostly because I feel that as the sub plays higher, my ear is drawn backwards more. The higher the sub plays, the more easily localized it is.
> 
> ...


well I believe that this is the heart of this discussion. Which sub have you tried to 'run high'? A low mass, high efficiency driver or a high mass/inneficient driver? I have a hunch that its the latter...


----------



## Steak (Mar 16, 2006)

chad said:


> I can tolerate 65-70, it's the people that swear by 50 cycles and lower is where I wonder. Here's a question.... do you run a sealed or vented alignment?


I suppose we cant tackle this issue without taking into consideration the rest of the system. Probably if you run dedicated 8" midbasses upfront you could get away with a low crossover on the sub...

Now here is another idea *puts the flame suit on*; why not run a prosound woofer to handle 40 - 100 Hz, AND a high excursion sub to handle sub 40Hz??
... Best of both worlds...


----------



## WRX/Z28 (Feb 21, 2008)

chad said:


> I can tolerate 65-70, it's the people that swear by 50 cycles and lower is where I wonder. Here's a question.... do you run a sealed or vented alignment?


Generally sealed, but I have run a few vented enclosures as well. 




Steak said:


> well I believe that this is the heart of this discussion. Which sub have you tried to 'run high'? A low mass, high efficiency driver or a high mass/inneficient driver? I have a hunch that its the latter...


I've run dozens of different subs over the years. Not too much in the high mass/inefficient department IIRC.


----------



## Steak (Mar 16, 2006)

WRX/Z28 said:


> I've run dozens of different subs over the years. Not too much in the high mass/inefficient department IIRC.


Did you mean low mass/efficient - or have you actually ran many prosound type woofers?


----------



## chad (Jun 30, 2005)

WRX/Z28 said:


> Generally sealed, but I have run a few vented enclosures as well.


Did not know if we were dealing with tiny enclosures.


----------



## WRX/Z28 (Feb 21, 2008)

Steak said:


> Did you mean low mass/efficient - or have you actually ran many prosound type woofers?


I meant I haven't run many inefficient or high mass subs. 

Not too much in the prosound dept., but I'm not running the 80something db woofers either. I've owned, or demo'd practically every major brand subwoofer at one point or another. 

For my own use. Mostly 1 cube to 1.25 cube sealed enclosures to save space. Almost always single sub setups, and almost always 12" woofers. 

I find that a single 12" sub in a sealed enclosure usually gives me the best compromise of small/medium enclosure, decent output, flat response, and low end extention.


----------



## Steak (Mar 16, 2006)

Well clearly by innefficient I meant as compared to proaudio, ie under 90db 1W/1m.



> ..but I'm not running the 80something db woofers either..


If you arent running proaudio (90something dB usuarlly 95-98), and you say you arent into inefficient subs either (80something dB), then which subs are you using?? Ribbon subs???


----------



## WRX/Z28 (Feb 21, 2008)

Steak said:


> Well clearly by innefficient I meant as compared to proaudio, ie under 90db 1W/1m.
> 
> 
> 
> If you arent running proaudio (90something dB usuarlly 95-98), and you say you arent into inefficient subs either (80something dB), then which subs are you using?? Ribbon subs???


Nah, GTO, GT5 JBL's... MTX T7500 (all are around 93db), JL 12w0, 12w3 91db IIRC. TC sounds 91db efficient.


----------



## aztec1 (Jun 13, 2008)

Steak said:


> Well what I can gather from that post from Mr Danley are basically two things:
> 
> 1. As it is well known, a sealed box rolls of less quickly than a vented box. 12dB per octave vs 24dB per octave. Thus the sealed box should play a 'flatter', wider bandwiidth than the vented design.
> 
> ...


Depending on the center frequency of the cabin gain, would it be possible for the peak to cause an even sharper rolloff in a vented alignment? Also, I'm trying to wrap my head around the vent being a phase inverter that might lessen punch. How would it do that? Does the vent act like another speaker wired out of phase with the sub? 

Is the reason why I prefer a sealed over vented alignment due to the inherent qualities of a speaker designed for a sealed box, vs. a vented one, or the characteristics of the vent itself?

Sorry for all the noobish questions.


----------



## Wheres The Butta (Jun 6, 2009)

I've got a little personal experience and a question to add to this.

In my experience, my subs are "boomy" for two reasons. First - because of the location. Try this experiment and see if you agree with me after it.

Listen to a subwoofer in a trunk. Listen to the same subwoofer in the same enclosure with the same power except put it outside the trunk on the ground. It will sound drastically different. I don't think it's just cabin gain, I think the reflected sound simply doesn't sound the same... I feel like some "tightness" and accuracy is lost simply by reflecting the sound.

Also, something that I think causes people to cross their subwoofer at absurdly low levels.... Because the subwoofer generally has a much higher level of output than the other speakers, it will drown everything else out if it's playing all the way up to 80hz. It seems like common sense that bass will sound "boomy" when you've got 1000 watts of subwoofer and 200 watts of front stage.... Under 50 hz though, bass seems less intrusive (even if it's loud) so I think it's a good place to cross the subwoofer over to prevent it overpowering everything.

I personally love a powerful substage because it can produce a forceful kick - the sort of bass you feel rather than hear.


----------



## Steak (Mar 16, 2006)

WRX/Z28 said:


> Nah, GTO, GT5 JBL's... MTX T7500 (all are around 93db), JL 12w0, 12w3 91db IIRC. TC sounds 91db efficient.


well fvck then Im lost again...
btw nice subs you've played with


----------



## WRX/Z28 (Feb 21, 2008)

Steak said:


> well fvck then Im lost again...
> btw nice subs you've played with


Crap, I left out Focal's polyglass 33v2 90db, and their 33kx 90db. 

Their Access 30a1 is 94db efficient.


----------



## Steak (Mar 16, 2006)

aztec1 said:


> Depending on the center frequency of the cabin gain, would it be possible for the peak to cause an even sharper rolloff in a vented alignment? Also, I'm trying to wrap my head around the vent being a phase inverter that might lessen punch. How would it do that? Does the vent act like another speaker wired out of phase with the sub?
> 
> Is the reason why I prefer a sealed over vented alignment due to the inherent qualities of a speaker designed for a sealed box, vs. a vented one, or the characteristics of the vent itself?
> 
> Sorry for all the noobish questions.


1. IIRC, from some cabin gain graph Mr Wehmeyer posted about cabin gain, the lower the frequency, the higher the amount of cabin gain. If that is true (I have a bad memory, please correct me if Im wrong) there is more gain from a lower band (such as 20 - 40Hz) than a higher band (such as 40 - Hz). So if one were to tune a sub to, say 40Hz, cabin gain should be more help where the sub rolls of quickly, ie below 40Hz, than over 40Hz.

2. From what I understood from Mr Danley's post, the sound wave reflects off the back on the enclosure and then into the vent, thus it has to travel twice the distance before it leaves the enclosure, so it is delayed by have a wavelength (this is my newb interpretation, please correct me if this doesnt make any sense). But alas, from Chad's previous post, apparently you'd have to have golden ears to notice this phase change...

About being newbie, dont worry, Im one too. I figure the only way to learn is to read(theory), try(hands on experience), and then ask whenever something doesnt make sense.


----------



## Steak (Mar 16, 2006)

WRX/Z28 said:


> Crap, I left out Focal's polyglass 33v2 90db, and their 33kx 90db.
> 
> Their Access 30a1 is 94db efficient.


on a side note, how did you like that 33kx? I'll try myself the 38kx (95dB 1W/1m) in a few days and post a review...


----------



## WRX/Z28 (Feb 21, 2008)

Steak said:


> on a side note, how did you like that 33kx? I'll try myself the 38kx (95dB 1W/1m) in a few days and post a review...


I loved it. My buddy has one in an S2000 off an Audison lrx something or other that make 900rms at 1ohm. Bass is solid, and very powerful. He's got another audison lrx something powering a set of Focal's 165k2p's. The car sounds incredible with very minimal tuning. No major processing, and all through the passive crossovers. It doesn't hurt that he has a factory hardtop on the car.

BTW, what is a 38kx? maybe 40kx?


----------



## aztec1 (Jun 13, 2008)

I'm feeling it start to click...thanks Steak and Chad for helping clarify this for me. I also read this from Zaph which helped too. The reason I brought up vents is because I've never seen nor heard a pro woofer in a sealed alignment, yet they consistently pack far more punch which seems to contradict the internet belief that sealed = "tighter".

There's always a tradeoff. :bulb2:


----------



## Steak (Mar 16, 2006)

WRX/Z28 said:


> I loved it. My buddy has one in an S2000 off an Audison lrx something or other that make 900rms at 1ohm. Bass is solid, and very powerful. He's got another audison lrx something powering a set of Focal's 165k2p's. The car sounds incredible with very minimal tuning. No major processing, and all through the passive crossovers. It doesn't hurt that he has a factory hardtop on the car.
> 
> BTW, what is a 38kx? maybe 40kx?


No, its actually called 38KX - SPL. Previous (circa 2000) model. High efficiency, high Fs, low xmax, low inductance...

http://www.diymobileaudio.com/forum...6-focal-38kx-spl-15-subwoofer.html#post822105

focal
Focal Polykevlar Speakers

just to add to the conversation, an older post by werewolf:



> hee hee ... if anyone is still reading, this is it ... the summary
> 
> The sub's time-domain transient response is related to the frequency-domain response through the unique Fourier Transform.
> 
> ...


----------



## thehatedguy (May 4, 2007)

Maybe. I haven't decided on what to do for bass in the new car. Everything else is planned and good to go...but subwooferage, I just can't make up my mind. I am spending more time worrying about speakers that probably will cover a whole 2 1/2 octaves than anything else.

Go figure.



Steak said:


> I suppose that is why THG runs a couple of sealed/IB IDW15s


----------



## chad (Jun 30, 2005)

thehatedguy said:


> I am spending more time worrying about speakers that probably will cover a whole 2 1/2 octaves than anything else.
> 
> Go figure.


Let it go, too many people do to be honest. :laugh::laugh::laugh:

To all.. if it's too "boomy" try one thing... back the gain off a bit, just a bit.. then the next day... back it off some more... keep doing this.

See what happens.


----------



## 60ndown (Feb 8, 2007)

chad said:


> Let it go, too many people do to be honest. :laugh::laugh::laugh:
> 
> To all.. if it's too "boomy" try one thing... back the gain off a bit, just a bit.. then the next day... back it off some more... keep doing this.
> 
> See what happens.


it might just be a very tight freq band (46-53 hz for example) causing the 'boom' so eqing out the exact freq instead of removing all your subsonic, is also an option.

melissa.


----------



## chad (Jun 30, 2005)

46 to 53

Did you pull that out of your ass Shaniqua?

Let's at least talk in standard ISO 1/3 octave increments


----------



## thehatedguy (May 4, 2007)

I know. Trying to decide between "real" bass and "fun" bass...and keeping as much trunk space as possible. When you have 10 pounds of **** to stuff into a 5 pound bag and still need to use the bag compromises have to be made.

Hearing Steve Head's Civic last month really made me re-evaluate what I am after in terms of bass.

"Real" bass probably will start to fall on it's face after 30-35 hertz and won't give you a back massage. Fun bass can do all of those neat special effects stuff while giving you a back massage. And I don't know of an easy way to blend the two....well I do, but it would mean buying more equipment.



chad said:


> Let it go, too many people do to be honest. :laugh::laugh::laugh:
> 
> To all.. if it's too "boomy" try one thing... back the gain off a bit, just a bit.. then the next day... back it off some more... keep doing this.
> 
> See what happens.


----------



## Steak (Mar 16, 2006)

thehatedguy said:


> I know. Trying to decide between "real" bass and "fun" bass...and keeping as much trunk space as possible. When you have 10 pounds of **** to stuff into a 5 pound bag and still need to use the bag compromises have to be made.
> 
> Hearing Steve Head's Civic last month really made me re-evaluate what I am after in terms of bass.
> 
> "Real" bass probably will start to fall on it's face after 30-35 hertz and won't give you a back massage. Fun bass can do all of those neat special effects stuff while giving you a back massage. And I don't know of an easy way to blend the two....well I do, but it would mean buying more equipment.


is Audionutz still runing a ported wgti?


----------



## thehatedguy (May 4, 2007)

The Civic has an Oz 250H under each front seat. The truck is still using the JBL subs.


----------



## Fixtion (Aug 25, 2006)

thehatedguy said:


> The Civic has an Oz 250H under each front seat. The truck is still using the JBL subs.


under seat is a pretty good alternative to cutting your floor.
still working out the details, perhaps a build log within a month.


----------



## thehatedguy (May 4, 2007)

They are IB, so there is a big hole cut for the magnet to hang out of.


----------



## Wheres The Butta (Jun 6, 2009)

Ok, so tell me how you think this woofer will do:

Black and White BTL 15" for BD5034 - Car Audio Classifieds

That's what I'm going to be using. It's very sensitive even before break in, and it's 15" so it's got some good cone area - but it's also extremely high excursion. 

It's going into a 4.5 cube (net) box that's tuned to 30hz. What are your thoughts - a woofer that's big and efficient but ALSO high excursion.


----------



## Fixtion (Aug 25, 2006)

thehatedguy said:


> They are IB, so there is a big hole cut for the magnet to hang out of.


yeah, that's how mine is setup, except they are not "secured".
haha, i love it though.


----------



## Fixtion (Aug 25, 2006)

bd5034 said:


> Ok, so tell me how you think this woofer will do:
> 
> Black and White BTL 15" for BD5034 - Car Audio Classifieds
> 
> ...


that's a beautiful sub but seriously . . . **** it. :\


----------



## Wheres The Butta (Jun 6, 2009)

Fixtion said:


> that's a beautiful sub but seriously . . . **** it. :\


haha the **** it is like a signature from the guy that built it.

edit: it also reflects the badass character of this sub. It's going to be pretty loud 0.o


----------



## sqshoestring (Jun 19, 2007)

I also disagree with the 'tight-punchy' and 'loose' type of descriptions. If you had a sub that was perfectly flat, you could make it sound any way you wanted with an EQ....and what ever way you did it, it would not really be SQ because punch would be a peak at high bass and thump at low bass....not flat. That said I like plenty of bass in the car, enough to hear it well then double it and that is about right. Still it is harder to hear flat unless you put 500lb of deadening in your car and I don't do that...so I need more bass.

Sealed vs ported, heck most cars only go to 30-35Hz anyway so you can port that low and have a great bottom. Or sealed can reach that with EQ or the right sub. Less than say 40Hz I doubt most people will note a phase issue in a car, or any non-show type system at least.

Chad was wondering about sub 30Hz and why would you have it in a car? I love it, the music has presence that is not there without kind of like a good threater. But since I mostly use IB (sealed with even less roll off) to get it and even with multiple drivers, I still need more power and EQ to produce 20-30Hz. Its the power like you said, and you need cone area and/or xmax to pull it off thus my quad 12s. Then if you have that much in your subs, sure it wants to over power anything else and that is why I LP at 35-50Hz. It gladly plays above that just because I don't have the most inefficient sub that will not. With more efficient subs it is worse at over running the LP. The issue then becomes when you EQ it, you are messing with the midbass that you _don't_ want to turn down. This is when different slopes can really help.

So what about cabin gain? Some cars you can run a sub that will just touch 30Hz and it works. I often have problems getting under that however. So this car was doing that with boxes, and I went overboard with quad 12s IB. I have to EQ the subs up at 20-30Hz and down at 50Hz to get to what sounds like roughly flat with tones. To me SQ is hearing all the music, at 20Hz or 50 or 5K, all the same to me. But getting under 30 seems to take some effort in my experience. Sure some cars I just can't fit what I need so I don't, but this one I could. Some cars I think I had close to that response with 10s, must have had a lot of cabin gain.


----------



## 14642 (May 19, 2008)

1. Flat response is flat response and identical response is the same. Two woofers that sound the same sound the same, no matter the possible xmax or any other parameter.
2. As someone stated, tight punchy bass is midbass. 
3. Woofers with highly inductive coils don't make great midbass--those kinds of coils are often used in car audio woofers designed for sealed boxes (long xmax).
4. It is possible to have long xmax for high output capability without high inductance.

The post on the AVS forum is too long for me to read, but there's a sloppy assumption made at the beginning and that is that a sub with lots of excusrion capability HAS to be highly inductive and inefficient. While that is often the case, it isn't always the case.


----------



## chad (Jun 30, 2005)

sqshoestring said:


> Chad was wondering about sub 30Hz and why would you have it in a car?


No, No, I said it does not concern me in a live setting... because of impossible coverage, amount of enclosures, and the power demands it would take...... re-read that, I said nothing about the car, in fact I said cars are easlily reaching LOWER than 20 cycles.

This is why soundguys don't carry around Bass Mekanik CD's


----------



## sqshoestring (Jun 19, 2007)

chad said:


> No, No, I said it does not concern me in a live setting... because of impossible coverage, amount of enclosures, and the power demands it would take...... re-read that, I said nothing about the car, in fact I said cars are easlily reaching LOWER than 20 cycles.
> 
> This is why soundguys don't carry around Bass Mekanik CD's


My bad Chad. Yeah I know a loaded box or horn that would go that low would be huge and so not very portable. I'm sure I can feel 10Hz/etc in my car, the real problem I have is recordings with weak bass; I boost them up and have to EQ them not just crank the sub amp level...then have to swap multiple EQ settings...its a pita. Something like a 5 or 7 band EQ would be nicer just to match up to recordings.

Andy- Isn't the inductance mostly a factor of power handling, or at least the easy way to that? On the other hand I've never run a sub over about 70Hz LP. With a 12db slope an efficient sub can run up to 100Hz that way and IMO gets localized in most installs. Even my infinitys that are kind of low Q IB will peak at 60Hz plus so I LP at 50 or lower when I had an xover that went lower. So they play at least up to 80 that way. In other words it seems common for me to still have a big roll off on the bottom to compensate for even with cabin gain.(in most cars not all, and to get well under 35Hz) I do have a sub I used in a box that sounded the same at 80Hz LP as 200LP, lol, but it could hardly hit 30 in the spec sealed so I deemed it worthless. The infinity in spec sealed was the same, but IB it reaches deeper than many others.


----------



## MasterODisaster (Dec 16, 2009)

I was reading this up to page 3 or so, but just wanted to add that a woofer can only be at one place at a time, and if you want REAL LOW BASS - you have to allow that woofer to reproduce those lower frequencies by crossing the amp over lower so it doesn't attempt to reproduce higher frequencies while reproducing the lower frequencies - if that makes sense...


----------



## chad (Jun 30, 2005)

nope, the cone can and will modulate over an excursion stroke... It has to in order to reproduce music


----------



## MasterODisaster (Dec 16, 2009)

chad said:


> nope, the cone can and will modulate over an excursion stroke... It has to in order to reproduce music


If a woofer is allowed to produce lower bass tones ONLY (by crossing over lower) it doesn't have to produce the higher tones (that distract it) while producing those lower tones, it can utilize it's energy to a greater effect at those lower frequencies. I realize there is a wave form that the woofer is attempting to translate into air pressure, but it can sound "lower" if crossed over at a lower frequency. This would be why someone would want a lower crossover point.


----------



## 94VG30DE (Nov 28, 2007)

MasterODisaster said:


> If a woofer is allowed to produce lower bass tones ONLY (by crossing over lower) it doesn't have to produce the higher tones (that distract it) while producing those lower tones, it can utilize it's energy to a greater effect at those lower frequencies. I realize there is a wave form that the woofer is attempting to translate into air pressure, but it can sound "lower" if crossed over at a lower frequency. This would be why someone would want a lower crossover point.


----------



## chad (Jun 30, 2005)

Someone is not getting it.


----------



## ErinH (Feb 14, 2007)

MasterODisaster said:


> If a woofer is allowed to produce lower bass tones ONLY (by crossing over lower) it doesn't have to produce the higher tones (that distract it) while producing those lower tones, it can utilize it's energy to a greater effect at those lower frequencies. I realize there is a wave form that the woofer is attempting to translate into air pressure, but it can sound "lower" if crossed over at a lower frequency. This would be why someone would want a lower crossover point.



Do what?


Sent from my iPhone. Pardon the grammar.


----------



## thehatedguy (May 4, 2007)

To make sounds, the cone has to modulate.

To make A sound, the cone just goes back and forward at a certain speed...or would it be velocity? 

Anyways, if you want a mix of tones (music), it is going to have to move at a mixed (modulated) rate.


----------



## chad (Jun 30, 2005)

or you would have an "infinite way" system.


----------



## minbari (Mar 3, 2011)

MasterODisaster said:


> If a woofer is allowed to produce lower bass tones ONLY (by crossing over lower) it doesn't have to produce the higher tones (that distract it) while producing those lower tones, it can utilize it's energy to a greater effect at those lower frequencies. I realize there is a wave form that the woofer is attempting to translate into air pressure, but it can sound "lower" if crossed over at a lower frequency. This would be why someone would want a lower crossover point.


Sorry, but you are talking out of you're ass. That is not how speakers work

Sent from my Motorola Electrify using Tapatalk 2


----------



## MasterODisaster (Dec 16, 2009)

A woofer (object with mass - cone, coil, and cap) will move at 30 cycles per second easier (and create a more defined pressure wave) if not having to move at frequencies greater than 30HZ simultaneously - right?

I know when I cross my amp over lower and allow the woofers to move more freely below that crossover point I hear less cone distortion - it may be just certain frequencies create a more distorted noise characteristic and that is tricking me into thinking it's the woofer playing better at lower notes.

Just chill on the attitudes brahz.


----------



## ErinH (Feb 14, 2007)

MasterODisaster said:


> A woofer (object with mass - cone, coil, and cap) will move at 30 cycles per second easier (and create a more defined pressure wave) if not having to move at frequencies greater than 30HZ simultaneously - right?
> 
> I know when I cross my amp over lower and allow the woofers to move more freely below that crossover point I hear less cone distortion - it may be just certain frequencies create a more distorted noise characteristic and that is tricking me into thinking it's the woofer playing better at lower notes.


Let's suspend the hypothesis for a second and think about reality: when do you listen to a single tone? Never. Not unless you are specifically looking to measure some nth order parameter and even then it's of little relative significance other than to clue you in on driver stress (ie: Xmax). 
Distortion is a mixed bag; inter modulated distortion (driver playing multiple tones at the same time) is real life and is what really drives component distortion to audibility. 
So while you're discussing the idea that a woofer playing a single tone does so more freely (not really sure what your point is here), keep in mind you never listen to a single tone and basing an argument on it is really without merit unless you're testing for something in particular. 

To be honest, I'm not really sure what point you're trying to make. but I've not got an attitude. I just flat out have no idea what you're trying to get to. 




Sent from my iPhone. Pardon the grammar.


----------



## MasterODisaster (Dec 16, 2009)

So you don't think in modern electronic music (created by synthesizers that can create perfect bass tones) there are times when a woofer can perfectly oscillate at 30 HZ to create a "rumble effect" and that it would do that more effectively if crossed over lower? I just saw this forum post when I was looking for a woofer with the highest xmax - I'm thinking W7, but waiting to try the 2012 Alpine Type R.

I can see how someone would think it's bogus. I guess I was just trying to validate my theory and it sounds like yall don't agree...

Hehe.


----------



## thehatedguy (May 4, 2007)

Nah, because music (anything other than a pure continuous tone) doesn't work that way.


----------



## cubdenno (Nov 10, 2007)

MasterODisaster said:


> So you don't think in modern electronic music (*created by synthesizers that can create perfect bass tones*) there are times when a woofer can perfectly oscillate at 30 HZ to create a "rumble effect" and that it would do that more effectively if crossed over lower? I just saw this forum post when *I was looking for a woofer with the highest xmax - I'm thinking W7, but waiting to try the 2012 Alpine Type R.*
> 
> I can see how someone would think it's bogus. I guess I was just trying to validate my theory and it sounds like yall don't agree...
> 
> Hehe.


give a look at the TC Axis or Ultra lines.

you are forgetting about harmonics let alone other issues..


----------



## chad (Jun 30, 2005)

MasterODisaster said:


> So you don't think in modern electronic music (created by synthesizers that can create perfect bass tones)


that just does not happen, the original 808 kick was developed from a gated sine wave, then **** was added to it because it sucked so bad.


----------



## MasterODisaster (Dec 16, 2009)

Upon inspection with my oscilloscope I see a waveform looks much "cleaner", and more of a proper sine wave at lower crossover points. This somewhat confirms my thoughts of allowing the woofer to move easier at the lower frequencies if you cut out the higher "distortiony" frequencies.

Yes?


----------



## chad (Jun 30, 2005)

A waveform of what? A sine wave? If not how can a complex waveform look cleaner?


----------



## minbari (Mar 3, 2011)

Give up Chad, lol. can't convince religious fanatics, lol.

Sent from my Motorola Electrify using Tapatalk 2


----------



## chad (Jun 30, 2005)

only a couple more hours till I slumber for hellweek at work. Then I have to give up.


----------



## MiniVanMan (Jun 28, 2005)

Ooooooh, can I play too??

Because I have a question? Which frequencies are more "distortiony" than others?

Erin, did you know that in order to find the distortion characteristics of a subwoofer, all you need is an o-scope? Man, I bet you feel stupid now with all that fancy test equipment, gadgety crap. 

Let me see if I can explain it.

A 45 hz signal is not going to cause resonance or distortion at 30 hz. If a 45 hz signal is distorted, it's the 45 hz signal, and... wait for it... it's harmonics (45, 90, 135, 180, etc, etc). The harmonics could distort. So, your 30 hz signal may distort at 60 hz, 90 hz, 120 hz, etc, etc. These are measurable, and it's called harmonic distortion. Unfortunately, harmonics are a huge part of music reproduction. Take out the harmonics and you have yech.

So, if you have a subwoofer that is audibly distorting at the F2 of 30 hz (60 hz), one, get another subwoofer, and two, get another subwoofer. 

Now, please don't tell me that by crossing lower, and having a 6 1/2" driver pick up the slack at 60 hz is a better option. I'll have to start getting impolite. 

If your subwoofer is only capable of a small assed bandwidth, it's a crap subwoofer. A decent 10" subwoofer that can play 30 hz, should get you to 120 hz just fine. That's 2 octaves. 

We measure speakers for distortion at the fundamental, the harmonics and the intermodular (in between the harmonics). So, I think I know what you're saying now. By eliminating the harmonic, you have a pure signal. What we're trying to tell you is that you don't want to do that. The harmonic is critical to musical reproduction.


----------



## BuickGN (May 29, 2009)

minbari said:


> Give up Chad, lol. can't convince religious fanatics, lol.
> 
> Sent from my Motorola Electrify using Tapatalk 2


Huh?


----------



## 24th-Alchemist (Jun 16, 2011)

> I was reading this up to page 3 or so, but just wanted to add that a woofer can only be at one place at a time, and if you want REAL LOW BASS - you have to allow that woofer to reproduce those lower frequencies by crossing the amp over lower so it doesn't attempt to reproduce higher frequencies while reproducing the lower frequencies - if that makes sense...





> If a woofer is allowed to produce lower bass tones ONLY (by crossing over lower) it doesn't have to produce the higher tones (that distract it) while producing those lower tones, it can utilize it's energy to a greater effect at those lower frequencies. I realize there is a wave form that the woofer is attempting to translate into air pressure, but it can sound "lower" if crossed over at a lower frequency. This would be why someone would want a lower crossover point.





> A woofer (object with mass - cone, coil, and cap) will move at 30 cycles per second easier (and create a more defined pressure wave) if not having to move at frequencies greater than 30HZ simultaneously - right?
> 
> I know when I cross my amp over lower and allow the woofers to move more freely below that crossover point I hear less cone distortion - it may be just certain frequencies create a more distorted noise characteristic and that is tricking me into thinking it's the woofer playing better at lower notes.
> 
> Just chill on the attitudes brahz.





> So you don't think in modern electronic music (created by synthesizers that can create perfect bass tones) there are times when a woofer can perfectly oscillate at 30 HZ to create a "rumble effect" and that it would do that more effectively if crossed over lower? I just saw this forum post when I was looking for a woofer with the highest xmax - I'm thinking W7, but waiting to try the 2012 Alpine Type R.
> 
> I can see how someone would think it's bogus. I guess I was just trying to validate my theory and it sounds like yall don't agree...
> 
> Hehe.





> Upon inspection with my oscilloscope I see a waveform looks much "cleaner", and more of a proper sine wave at lower crossover points. This somewhat confirms my thoughts of allowing the woofer to move easier at the lower frequencies if you cut out the higher "distortiony" frequencies.
> 
> Yes?
> 11 Hours Ago 10:38 AM



========================================


For the most part I agree with the quotes above from _MasterODisaster_. (I don't like the non-technical adjectives but I agree with the main ideas). In particular it seems reasonable to me that "_[a subwoofer] can sound "lower" if crossed over at a lower frequency_". One important factor is that Xmax (linear stroke) is limited in all woofers. Therefore when maximal performance in the lowest octaves is desired, it makes intuitive sense to devote a limited amount of linear stroke solely to the lowest frequency bands as _MasterODisaster_ describes. 

Instead of just making claims about things, let's take a look:










In the top plot two woofer excursion waveforms are shown:
BLUE trace: for a 30 Hz unit sinusoid input;
PURPLE trace: for 30 Hz unit sinusoid + 100 Hz unit sinusoid input.

To model the effects of limited linear stroke (Xmax), excursion amplitudes exceeding one unit in magnitude are compressed by a square root function.

In the lower plot spectral estimates of the two excursion waveforms are shown. The colors in the lower plot correspond to the colors of the excursion waveforms in the upper plot.

Here are two things shown by the lower plot:

The power in the 30 Hz region of the combined 30+100 HZ waveform (i.e not lowpassed) is >1.5 dB *_less_* than the power of the pure 30 Hz signal. This is true even though in both cases the amplitudes of the 30 Hz input signals are *identical*. This is consistent with the statements from _MasterODistaster_ about how a low-passed woofer can "_utilize it's energy to a greater effect at those lower frequencies_".
The widening of the purple spectral estimate (30+100 Hz wave) at both the 30 and 100 Hz areas is distortion. The additional bimodal peak at around 160 Hz is distortion. This is in line with the statements from _MasterODisaster_ about how allowing more high frequency content to pass to a sub increases distortion.

If we model with more realistic signals the results are harder to interpret but the effects described above do not change. They hinge on the fact that for all real woofers their linear ranges are not unlimited.

-----------------------------------



> can't convince religious fanatics


I think the quote above applies more to recent posters whose user names are not _MasterODisaster_.

--------------------------------

Does saying 1+1 does not equal 3 refute anything written by _MasterODisaster_?

Does writing arbitrary facts about distortion measurements address what _MasterODisaster_ is writing about?


----------



## MasterODisaster (Dec 16, 2009)

While playing a song (electronic "predictable beat" music) - it was clearly showing a smoother line when crossed over at 50Hz vs 125Hz which would mean the power that is being sent to the woofer is telling the woofer to move in a more "flowy" manner. Not having to adjust it's path during one stroke of positive/negative motion, er, uh... Ahhhhh - I give up...


----------



## MasterODisaster (Dec 16, 2009)

Sorry - didn't even read those last posts on the next page. You guys helped me out nicely. Happy "sensible sound" guys. Some of you DO need to try and sound less condescending though.

Thanks for your time.


----------



## BuickGN (May 29, 2009)

I have no idea who is right, both kind of make sense. But I figure there's a lot less distortion from having the sub play a little higher than making a little 6.5" cover 50hz. I finally bottomed my Esotar 650 with it crossed at 50hz and playing it loudly. That's the worst sound I've ever heard, I swear it's louder than any speaker I've ever heard bottom and I was cranking the volume up slowly(maybe the 3" VC?). I immediately brought the midbass and sub up to 80hz and to tell you the truth it sounds better that way. Still interested in this thread, it's something I've wondered about for a long time since I tend to let the sub play up to 120hz at times.


----------



## chad (Jun 30, 2005)

Let's say the theory was true (it's not) the part suffering would not be the lower note, it would be the upper from trying to ride on top of the lower freq modulation. 

So riddle me this. How the hell can a driver play from say, 80 to 2.5K?

As for the graphs, wanna see something uglier? Superimpose a 35 cycle tone on a 30 cycle tone


----------



## MarkZ (Dec 5, 2005)

24th-Alchemist said:


> Here are two things shown by the lower plot:
> 
> The power in the 30 Hz region of the combined 30+100 HZ waveform (i.e not lowpassed) is >1.5 dB *_less_* than the power of the pure 30 Hz signal. This is true even though in both cases the amplitudes of the 30 Hz input signals are *identical*. This is consistent with the statements from _MasterODistaster_ about how a low-passed woofer can "_utilize it's energy to a greater effect at those lower frequencies_".
> The widening of the purple spectral estimate (30+100 Hz wave) at both the 30 and 100 Hz areas is distortion. The additional bimodal peak at around 160 Hz is distortion. This is in line with the statements from _MasterODisaster_ about how allowing more high frequency content to pass to a sub increases distortion.


The one thing I've learned from this post is that less clipping is better than more clipping.

Can you repeat the analysis, but this time use equal levels of power so that you can compare apples to apples?


----------



## 24th-Alchemist (Jun 16, 2011)

> I figure there's a lot less distortion from having the sub play a little higher than making a little 6.5" cover 50hz.


Absolutely. But I'm limiting my comments to whether low-passing a sub can improve it's performance in the lowest octaves.



> Can you repeat the analysis, but this time use equal levels of power so that you can compare apples to apples?


I contend that the simulation shown above is comparing apples to apples: the power in the 30 Hz input signals is identical in both cases. The request above hints at an alternative way of viewing sub low-passing: in particular that it reduces the total power delivered to the sub because the bandwidth is reduced (assuming relatively uniform power distribution in the bands of interest). If the total power of both signals is made equal of course the sub will distort in both cases. Nonetheless I think there's more to learn than just "_less clipping is better than more clipping._".

For example, _chad_ contends that



> the part suffering would not be the lower note, it would be the upper from trying to ride on top of the lower freq modulation.


This seems to be a reasonable hypothesis but when we check it with the simulations it is shown to be incorrect. The simulations show that it's not the 100 Hz signal that gets "chopped off" while the 30 Hz wave persists unscathed. Instead the simulations show (lower psd plot) that both waves are distorted (in amounts that appear to be quantitatively equal) and furthermore that the net output of the 30 Hz wave is *reduced* even though in both cases the net input of the 30 Hz waves are equal (apples to apples for this issue).


----------



## chad (Jun 30, 2005)

24th-Alchemist said:


> This seems to be a reasonable hypothesis but when we check it with the simulations it is shown to be incorrect.


[cough]doppler[/cough]

you cannot defy the laws of physics.

Did you try that 30/35 cycle thing yet?


----------



## ErinH (Feb 14, 2007)

Again, I'm not even refuting that a single tone will make a driver work less than when it is playing multitones. but, what does that prove? When do you listen to _a_ tone? 
I can say that flying with boots off is easier than flying with boots on, but if I can't even hover, what does it matter?


----------



## MarkZ (Dec 5, 2005)

24th-Alchemist said:


> I contend that the simulation shown above is comparing apples to apples: the power in the 30 Hz input signals is identical in both cases. The request above hints at an alternative way of viewing sub low-passing: in particular that it reduces the total power delivered to the sub because the bandwidth is reduced (assuming relatively uniform power distribution in the bands of interest). If the total power of both signals is made equal of course the sub will distort in both cases. Nonetheless I think there's more to learn than just "_less clipping is better than more clipping._".
> 
> For example, _chad_ contends that
> 
> ...


Since the nonlinearity that you're introducing is essentially dependent on power, and since you're comparing two cases of unequal power, then I think you have to be careful with what you're concluding. The reason the energy of the 30Hz component goes down is because you're forcing it to go down by virtue of the way you're modeling the nonlinearity. There's no reason why clipping should preferentially affect only one frequency... it's not a frequency-dependent nonlinearity!

So, yes, narrowing the passband reduces power, which means that you're clipping less. This is a phenomenon we talk about a lot around here, usually regarding HPFs and midrange speakers. It's common to suggest people run their HPFs higher if they suspect their speaker is bottoming out or their amp is clipping. This is sort of the opposite application... run your subwoofer with a lower LPF if you want to reduce the power to it.

For most users, the subwoofer (and sub amp) is much larger than the midranges, which is why I'm usually an advocate of higher crossover points.


----------



## chad (Jun 30, 2005)

MasterODisaster said:


> I was reading this up to page 3 or so, but just wanted to add that a woofer can only be at one place at a time, and if you want REAL LOW BASS - you have to allow that woofer to reproduce those lower frequencies by crossing the amp over lower so it doesn't attempt to reproduce higher frequencies while reproducing the lower frequencies - if that makes sense...





chad said:


> nope, the cone can and will modulate over an excursion stroke... It has to in order to reproduce music





bikinpunk said:


> Again, I'm not even refuting that a single tone will make a driver work less than when it is playing multitones. but, what does that prove? When do you listen to _a_ tone?
> I can say that flying with boots off is easier than flying with boots on, but if I can't even hover, what does it matter?



JUST LIKE THAT.... it comes full circle.


----------



## MarkZ (Dec 5, 2005)

bikinpunk said:


> Again, I'm not even refuting that a single tone will make a driver work less than when it is playing multitones.


Erin, I would refute that. There's nothing special about multiple tones (except maybe IMD issues, which you referred to earlier). The issue is whether the power increases or not. If you compare a single sine wave and bandlimited noise, the speaker won't work harder as long as the power is the same.

This is why I think it's important to compare the two under equal conditions. Otherwise, power is a confound.


----------



## ErinH (Feb 14, 2007)

MarkZ said:


> Since the nonlinearity that you're introducing is essentially dependent on power, and since you're comparing two cases of unequal power, then I think you have to be careful with what you're concluding. The reason the energy of the 30Hz component goes down is because you're forcing it to go down by virtue of the way you're modeling the nonlinearity. There's no reason why clipping should preferentially affect only one frequency... it's not a frequency-dependent nonlinearity!
> .



Someone smack me if I'm off my rocker here but... he's modeling a fundamental. So, why is there non-linearity in a _fundamental_?
There shouldn't be. If there is, then something is wrong (ie: clipping, which has been mentioned).


----------



## chad (Jun 30, 2005)

MarkZ said:


> Erin, I would refute that. There's nothing special about multiple tones (except maybe IMD issues, which you referred to earlier). The issue is whether the power increases or not. If you compare a single sine wave and bandlimited noise, the speaker won't work harder as long as the power is the same.
> 
> This is why I think it's important to compare the two under equal conditions. Otherwise, power is a confound.


I concur.


----------



## MarkZ (Dec 5, 2005)

bikinpunk said:


> Someone smack me if I'm off my rocker here but... he's modeling a fundamental. So, why is there non-linearity in a _fundamental_?
> There shouldn't be. If there is, then something is wrong (ie: clipping, which has been mentioned).


Yes, he introduced clipping in his model (or some form of limiting, I forget). I think his stance is that MasterOfDisaster's point holds true *if* you're overdriving the amplifier or speaker.


----------



## ErinH (Feb 14, 2007)

MarkZ said:


> Erin, I would refute that. There's nothing special about multiple tones (except maybe IMD issues, which you referred to earlier). The issue is whether the power increases or not. If you compare a single sine wave and bandlimited noise, the speaker won't work harder as long as the power is the same.
> 
> This is why I think it's important to compare the two under equal conditions. Otherwise, power is a confound.


I'll be honest, at some point I got lost in this conversation but what I'm still gripping tight to is the notion of llinearity/non-linearity in a fundamental of single or multi stimulus. It doesn't make sense. To me, it just really makes the argument false on its face. So, where I tie back in to what you're saying is the matter of clipped input signal which would cause a jacked up fundamental. But, regardless of a fundamental, we're not even looking at harmonics (IMD or not) in this discussion so how is there non-linearity if all you're seeing is a fundamental? 
Maybe I'm just retarded. It's been known to happen.


----------



## chad (Jun 30, 2005)

Well assuming the driver's efficiency does not change from power compression, etc it is going to do the same amount of work for a given power input. No matter what the waveform is. 

I feel some view a more complex waveform as working harder. Because its more crazy yo.


----------



## 24th-Alchemist (Jun 16, 2011)

> Since the nonlinearity that you're introducing is essentially dependent on power, and since you're comparing two cases of unequal power, then I think you have to be careful with what you're concluding. The reason the energy of the 30Hz component goes down is because you're forcing it to go down by virtue of the way you're modeling the nonlinearity. There's no reason why clipping should preferentially affect only one frequency... it's not a frequency-dependent nonlinearity!
> 
> So, yes, narrowing the passband reduces power, which means that you're clipping less. This is a phenomenon we talk about a lot around here, usually regarding HPFs and midrange speakers. It's common to suggest people run their HPFs higher if they suspect their speaker is bottoming out or their amp is clipping. This is sort of the opposite application... run your subwoofer with a lower LPF if you want to reduce the power to it.
> 
> For most users, the subwoofer (and sub amp) is much larger than the midranges, which is why I'm usually an advocate of higher crossover points.


I agree with the quote above. I've quoted other statements from this thread that to me don't appear to be consistent with what is stated above.



> The reason the energy of the 30Hz component goes down is because you're forcing it to go down by virtue of the way you're modeling the nonlinearity.


Of course. I'm the one who chose the model and that's why I chose it the way I did. I intended for it to refute what I have quoted from others who suggest otherwise.



> ... I think you have to be careful with what you're concluding.


Such is always true. I don't see how I've made any erroneous conclusions if that's what is being implied.


----------



## 24th-Alchemist (Jun 16, 2011)

> how is there non-linearity if all you're seeing is a fundamental


The psd plot shows that there are more than just the fundamentals. There are harmonics at 160 Hz for example, resulting from "soft clipping" the fundamentals with a square root function when the total input signal magnitude exceeds a certain bound. There are probably also harmonics above 160 Hz not shown in the psd.



> I'm not even refuting that a single tone will make a driver work less than when it is playing multitones. but, what does that prove?


I'm using 30 Hz and 100 Hz tones because to me they are easier to work with than time series whose Fourier transforms are distributed across frequency bands. The issue being explored here is not IMD and thus a tone (easy to work with point frequency representation) versus frequency band (more complicated to work with) is not the issue here. That's not to say it's not an issue for real life drivers, just not the issue here.

The same arguments apply for frequencies distributed around 30 and 100 Hz but their time series are harder to think about. People like to think about things in time-domain, frequency domain, peak amplitude and power and to me it's easy to think about sinusoids in all four ways. 

_Mark Z_ summarizes things nicely IMO if you're skeptical of my thoughts read his which up to this post I think are correct (except for if he's implying I'm misrepresenting things )


----------



## chad (Jun 30, 2005)

But you are STILL trying to imply that a high frequency played with a low frequency causes the low frequency to suffer. And IM distortion of HF is moot. 

And that is just not the case outside a vacuum playing music.


----------



## 24th-Alchemist (Jun 16, 2011)

chad said:


> But you are STILL trying to imply that a high frequency played with a low frequency causes the low frequency to suffer. And IM distortion of HF is moot.
> 
> And that is just not the case outside a vacuum playing music.



Statements such as the one quoted above are what motivated me to post what I thought would be an easy to understand counter-example that showed they are wrong.
I'm not "implying" anything. I'm stating it and it's shown in the plots.
Statements such as the one quoted above are worse than those from the medieval masses who insisted that the earth is flat: at least they could point to the horizon in an attempt to support their claims. _Chad_ explain how what is plotted above "_is just not the case_".


----------



## OSN (Nov 19, 2008)

24th-Alchemist said:


> Statements such as the one quoted above are what motivated me to post what I thought would be an easy to understand counter-example that showed they are wrong.
> I'm not "implying" anything. I'm stating it and it's shown in the plots.
> *Statements such as the one quoted above are worse than those from the medieval masses who insisted that the earth is flat:* at least they could point to the horizon in an attempt to support their claims. _Chad_ explain how what is plotted above "_is just not the case_".


----------



## chad (Jun 30, 2005)

We are just going to have to put this into a real world situation. We are getting 2 different things out of that graph, but I'm looking at it from a different angle.

Gimme a couple weeks to get over hell weeks at work, let's get some gear out.


----------



## ErinH (Feb 14, 2007)

I just hope Fs isn't at 30hz...


Sent from my iPhone. Pardon the grammar.


----------



## chad (Jun 30, 2005)

bikinpunk said:


> I just hope Fs isn't at 30hz...
> 
> 
> Sent from my iPhone. Pardon the grammar.


Meh, it's really a good number IMHO, no arguments there. My bump it up to 40 as that's where the subs I'll be using are more comfortable at. But what's 10Hz between friends?


----------



## CaptEditor (Nov 25, 2011)

so if 2 sine waves of differing frequencies create harmonics and distortion, at what point is it audible?

I would think that it would be most audible at high xmax and with a cone with a lot of mass, based on knowledge of momentum.

The same would happen during a large spectrum of frequencies at high xmax and especially with a high mass cone.

As others have posted, lets not jump to the condesending attitudes... We're all wrong sometimes -- some more than others. Most of the dumb questions are from people _trying to learn_!


----------



## MiniVanMan (Jun 28, 2005)

CaptEditor said:


> so if 2 sine waves of differing frequencies create harmonics and distortion, at what point is it audible?
> 
> I would think that it would be most audible at high xmax and with a cone with a lot of mass, based on knowledge of momentum.
> 
> ...


It's audible when you can hear it. 

HD and even distortion at the fundamental is going to be more prevalent at the two ends of the speaker's bandwidth. The reasons are different, but they still cause distortion. Motor running out of gas at the limits of the coil, and the point where the cone starts to resonate (just the cone) and break up. 

If you have high distortion in the middle of the bandwidth, it's an artifact, or just not a very good speaker, but even then, you'll still have higher distortion at the ends. 

What a good question would be are what frequencies are we more susceptable to distortion. Well, the answer follows the bell curve of your hearing. If you're most sensitive at 2k, you'll be more likely to pick out distortion. 30 hz? Nobody has stellar hearing at 30 hz. You can get away with a lot of distortion before it becomes audible.


----------



## bassfromspace (Jun 28, 2016)

At what point does the max portage of the port come into play?


----------



## thehatedguy (May 4, 2007)

Only at xmin.



bassfromspace said:


> At what point does the max portage of the port come into play?


----------



## Oscar (Jun 20, 2010)

bassfromspace said:


> At what point does the max portage of the port come into play?


haha..."portage"....never heard THAT term before. Awesome, lol.:laugh:


----------



## chad (Jun 30, 2005)

Oscar said:


> haha..."portage"....never heard THAT term before. Awesome, lol.:laugh:


Stick around.


----------

