# What does running active or passive mean?



## podog44 (May 4, 2010)

I read posts all over here that talk about running active or passive and still have no idea what it means?


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## basher8621 (Feb 21, 2009)

Running passive means you use the crossovers supplied with component sets. Active you will you seperate crossovers and eq such as the MS-8 or BitOne or something like that. Running active gives you more flexibility.


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## tanakasan (Sep 8, 2007)

And a dedicated amp/amp channel per driver.

Active = signal split actively/electronically in the low level realm before amplification. x2 on flexibility! 

Passive = highs/lows split after amplification, typically via coils and capacitors.

Robert


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## AudioDave (May 30, 2010)

Passive crossovers are networks built using capacitors and inductor coils. Active crossovers are generally line-level electronic signal processors that work between the amplifiers and the signal source. 

Active crossovers are generally "better" due to no phase shift, or loss of energy, and no coloration from the components in a passive filter resulting in much higher output quality. The disadvantage to active, is that every speaker or set of speakers (tweeters, mids, etc.) needs its own dedicated amplifier channel, and the system gets more expensive and complex doing things that way. Active crossovers are also generally adjustable as well, whereas most passives are not, or if they are, it's very limited.


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## MiniVanMan (Jun 28, 2005)

AudioDave said:


> Active crossovers are generally "better" due to no phase shift,


Wrong


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## AudioDave (May 30, 2010)

the better in quotes means subjective, not wrong.


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## Mythstery (Jun 8, 2010)

I was going to ask this question as well after reading a few posts on it. 

I have a set of PVI.216 mb quarts in the closet. does this mean i can get a EQ and run inline from HU to the AMP and then run a 4 chan amp for each piece of the front stage? tweets and mid driver. 

For those of us that cant afford the ms8 or bitone are there other alternatives?


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## naiku (May 28, 2008)

Mythstery said:


> For those of us that cant afford the ms8 or bitone are there other alternatives?


Yes, Alpine H701, H650, also there are many head units that allow you to run an active set up without a processor (Alpine 9887, Pioneer 800/880PRS, Kenwood X894, I think).


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## nineball (Jan 17, 2008)

an eq alone will not do it. you need some form of processing that controls the frequencies each speaker receives. the ms-8 is a nice unit but far from the only game in town. you can get a stand alone cheap-o 3 way crossover for well under $100. for example you could get something like this as an entry level component and then upgrade later if you want to get deeper.

CROSSFIRE CFX23 2/3-way crossover network - eBay (item 350368210800 end time Jun-21-10 20:37:41 PDT)


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## FG79 (Jun 30, 2008)

MiniVanMan said:


> Wrong


I agree.

People should refrain from injecting their personal preferences in this thread. If the OP wants to solicit these opinions, he can ask himself.

I won't go into my speech except to say that the whole passive/active debate is not as black and white as many people feel it is.


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## PorkCereal (Nov 24, 2009)

If you have never run active, try passive first and see if it fulfills your expectations. Then try bi-amping/bi-wireing if your passives will let you. Then try active. 

Going active with little to 0 knowledge of frequencies and crossovers might be a little hard.


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## MiniVanMan (Jun 28, 2005)

AudioDave said:


> the better in quotes means subjective, not wrong.


I don't care what your opinion is between passive and active. I was saying that your comment that active crossovers have no phase shift is WRONG.

They do have phase shift.


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## redcalimp5 (Sep 10, 2007)

MiniVanMan said:


> I don't care what your opinion is between passive and active. I was saying that your comment that active crossovers have no phase shift is WRONG.
> 
> They do have phase shift.


I know my older Alpine allows me to adjust phase. I'm running 2 way active + sub, processing is all controlled through the HU.


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## AudioDave (May 30, 2010)

MiniVanMan said:


> I don't care what your opinion is between passive and active. I was saying that your comment that active crossovers have no phase shift is WRONG.
> 
> They do have phase shift.


Ok explain to us all then how phase shift works in an active setup network. After you do, I will explain how time alignment such as Linkwitz Riley or Butterworth works to correct it. And I dont mean a button or switch on them that allows the user to change polarity shift of the speakers inputs. Maybe we are thinking 2 different things.


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## rexroadj (Oct 31, 2008)

Dave....Not starting anything with you at all on this, just informing you as you appear to be new on here....You know how you have said in other threads....."you dont know who I am" or to that effect? I will do it for minivan. Going at him about this stuff is like showing up to a knife fight with a q-tip. Again, not being an ass, just informing you. Not saying you dont know what your talking about either, just tread softly. 
I am sure he is completely sick of it by now but Minivan was a huge asset to me a while back in regards to passive networks and very approachable. 
On another note....I have had = success with both active and passive. It depends on how well designed the passives are! There was nothing I couldnt do active that I couldnt do with the alpine f1 passives.


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## AudioDave (May 30, 2010)

rexroadj said:


> Dave....Not starting anything with you at all on this, just informing you as you appear to be new on here....You know how you have said in other threads....."you dont know who I am" or to that effect? I will do it for minivan. Going at him about this stuff is like showing up to a knife fight with a q-tip. Again, not being an ass, just informing you. Not saying you dont know what your talking about either, just tread softly.
> I am sure he is completely sick of it by now but Minivan was a huge asset to me a while back in regards to passive networks and very approachable.
> On another note....I have had = success with both active and passive. It depends on how well designed the passives are! There was nothing I couldnt do active that I couldnt do with the alpine f1 passives.


nonononono not at all what I was implying and I am sorry if thats how it read. Hopwever just saying someone is flat wrong, especially without explaining why they say that, well thats treading too lol. Thats why I said maybe we are thinking 2 different things. As for who I am well its coming out of the bag lol...Grizz has a big mouth..... for beer!!


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## MarkZ (Dec 5, 2005)

AudioDave said:


> Ok explain to us all then how phase shift works in an active setup network. After you do, I will explain how time alignment such as Linkwitz Riley or Butterworth works to correct it. And I dont mean a button or switch on them that allows the user to change polarity shift of the speakers inputs. Maybe we are thinking 2 different things.


Analog active crossovers are identical in principle to analog passive crossovers. The primary difference between them is that the load is purely resistive and stable (ie. doesn't thermally drift appreciably), which means they're a bit more stable. But they still shift phase the same way all analog filters do. This is a natural result of the reactance in the circuit (reactance means the inductance and capacitance). Basic properties of capacitors and inductors here.

It's possible to design linear phase digital FIR filters, although you don't see it that frequently in car audio.

Anyway, MVM is right that "active" does not mean no phase shift. Especially in car audio where most active processors or amp controls are analog filters.


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## rexroadj (Oct 31, 2008)

Grizz is good people.....No I didnt think you were coming off like an ass on this at all.....You have in other threads though (dont know if you mean to or not?) Just letting you know this guy lives and breaths xovers! (not saying you dont? like you have said, no one knows who you are) On a side note.....Whats the big frigging deal? (not as it sounds, not saying it in a negative way!) We dont really care, not in a good or bad way. We have lots of accomplished people on here and most of us dont judge


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## rexroadj (Oct 31, 2008)

Oh yeah,(Dave) Markz is another one of those Tech guys that knows his ****!! I disagree with almost everything he says on a personal opinion non audio level, but he knows his **** when it comes to this type of stuff without question!


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## MiniVanMan (Jun 28, 2005)

AudioDave said:


> Ok explain to us all then how phase shift works in an active setup network. After you do, I will explain how time alignment such as Linkwitz Riley or Butterworth works to correct it. And I dont mean a button or switch on them that allows the user to change polarity shift of the speakers inputs. Maybe we are thinking 2 different things.


Noooo, I REALLY want to hear how a Linkwitz-Riley time alignment filter works. What the **** is Linkwitz-Riley time alignment??

So, you're telling me that you're going to tell me how to use a L/R, or Butterworth filter to correct phase shift? What does filter alignment have to do with phase shift. Slope order has to do with phase shift. Alignment has nothing to do with it. A 12db electrical filter, whether it be L/R, Butterworth, Bessel, or whatever alignment you want, WILL have a 180 degree phase shift. 

Now, if you want to get into the L/R 24 being "phase perfect", well, that's only sort of true. Linear Phase, and phase perfect elliptical filters are different animals. Regardless, even in those cases you're still dealing with phase shift, just compensating for it.

Analog active filters, as MarkZ pointed out, still have phase shift. FIR filters, which the only people using them would be CarPC guys, can be done without phase shift, but you get other problems induced. Engines that can run FIR filters are still rather clumsy and unintuitive. Better get your calculus hat on. 

Your comment "After you do, I will explain how time alignment such as Linkwitz Riley or Butterworth works to correct it" 100% tells me you do not know what you are talking about.

I continually speak out on how phase shift can be your friend in car audio. Embrace the phase shift.


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## MarkZ (Dec 5, 2005)

Tell it like it is.


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## AudioDave (May 30, 2010)

MiniVanMan said:


> Noooo, I REALLY want to hear how a Linkwitz-Riley time alignment filter works. What the **** is Linkwitz-Riley time alignment??
> 
> So, you're telling me that you're going to tell me how to use a L/R, or Butterworth filter to correct phase shift? What does filter alignment have to do with phase shift. Slope order has to do with phase shift. Alignment has nothing to do with it. A 12db electrical filter, whether it be L/R, Butterworth, Bessel, or whatever alignment you want, WILL have a 180 degree phase shift.
> 
> ...


Good gawd I tried..... That was driect negative to my reply of being nice. 

Guys heres the deal. I know my **** too as some are starting to say now. I design crossover networks all day long. I know exacatly what I am talking about.

You and I are not talking about the same thing as I said above. I am talking about axis, not polarity or linear phase shifting. 

What distinguishes the Linkwitz-Riley crossover design from others is its perfect combined radiation pattern of the two drivers at the crossover point. There is no tilt and no peaking -- just a perfect response whose only limitation is the dispersion characteristics of the drivers. The main contributor to this ideal response is the in-phase relationship between the crossover outputs.

Two of the cancellation nodes are still present, but are well defined and always symmetrical about the on-axis plane. Their location changes with crossover frequency and driver mounting geometry (distance between drivers). With the other designs, the peaking and cancellation axes change with frequency and driver spacing.There are 2 forms of cancellation when it is untimed and 1 when it is. When time alignment occurs, it creates and belnds all 3 forms so the listener feels the same impact and dynamics in the rear, as someone in say the front row would. Peaks are always flat at 0 because they are now corrected. (no shifting)

The cancellation nodes are not due to the crossover design, they are due to the vertically displaced drivers. (The crossover design controls where cancellation nodes occur, not that they occur.) The fact that the drivers are not coaxial means that any vertical deviation from the on-axis line results in a slight, but very significant difference in path lengths to the listener. This difference in distance traveled is effectively a phase shift between the drivers. And this causes cancellation nodes -- the greater the distance between drivers, the more nodes.

The other outstanding characteristic of the Linkwitz-Riley alignment is the rolloff rate of 24 dB/octave. With such a sharp drop-off, drivers can operate closer to their theoretical crossover points without the induced distortion normally caused by frequencies lying outside their capabilities. Frequencies just one octave away from the crossover point are already attenuated by 24 dB (a factor or about 1/16). The importance of sharp cutoff rate and in-phase frequency response of the crossover circuitry cannot be over-stressed in contributing to smooth overall system response with no phase shifting.

Butterworth

The filter type can be described in several different ways. Low-pass and high-pass filters in two-way crossover networks are often identified by their "Q". The Q is the resonance magnification of the filter and it is recognized by the shape of the "knee" of the amplitude response. Filters with a high Q tend to "ring" and exhibit poor transient response. Unlike drivers and boxes which use only numerical values for Q, filters are sometimes named after the engineer(s) who first described them.

The filters in three-way crossover networks (and some two-way networks) are often identified as either "APC" or "CPC" depending on the way they combine. APC stands for "All-Pass Crossover" and it refers to those crossover networks whose filters sum to create a flat voltage output. APC networks are generally considered the best choice because they make it possible for the speaker to have a flat on-axis amplitude response. Common APC networks include 1st- and 3rd-order Butterworth filters and 2nd- and 4th-order Linkwitz-Riley filters. 

CPC stands for "Constant-Power Crossover" and it refers to those crossovers whose filters sum to provide a flat power response. The power response of a speaker is the total of both its off-axis and on-axis amplitude response. In other words, it is the total acoustical power that is radiated into a space. CPC networks can be beneficial in reverberant environments where the off-axis response is important.


Ya know what else? I totally understand why Grizz and a few others are tired of forumns. It seems no matter how much help is offered or given, theres always a fight. I know there are many on here who know what they are talking about and I am by no means an expert on everything.

As for this thread, I am done. If the threadstarter wants to email me directly thats fine too I will gladly help them setup either.


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## MiniVanMan (Jun 28, 2005)

AudioDave said:


> Good gawd I tried..... That was driect negative to my reply of being nice.
> 
> Guys heres the deal. I know my **** too as some are starting to say now. I design crossover networks all day long. I know exacatly what I am talking about.
> 
> ...


EXCELLENT!!!!

Now put it into your own words so that I know you understand it.

Linkwitz-Riley Crossovers: A Primer

You could have saved a lot of time just linking the article you stole that from. You know why it was stealing? Because you didn't even attempt to give credit to the original article. Just like the install gallery you stated was yours. 

I'm seeing a pattern here. The forums would be better off without you.

Here's also a hint. When plagiarizing a published article, understand that the article probably went through an editor, and was corrected for grammatical errors. The plagiarized article had no grammatical errors that were immediately seen, but the limited amount that you actually wrote was wrought with spelling and grammatical errors. Not the worst I've seen, but enough for me to raise my eyebrows and notice a distinct difference in writing style. You managed to write a very technical, and long tutorial in near perfect form, but couldn't complete 10 introductory, and concluding sentences without errors. 

If you're going to plagiarize, be consistent, and be smart about it.


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## MarkZ (Dec 5, 2005)

Talk about backpedaling.

"Active crossovers are generally 'better' due to no phase shift..."

If people learned to say things like "Oh yeah I forgot" or "I was wrong" (or even nothing at all!) instead of arguing and twisting, this forum would be a much better place.


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## ChrisB (Jul 3, 2008)

MiniVanMan said:


> EXCELLENT!!!!
> 
> Now put it into your own words so that I know you understand it.
> 
> ...


Yet another failed attempt at plagiarism by AudioDave. Wow, just wow...


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## sam3535 (Jan 21, 2007)

AudioDave said:


> I know there are many on here who know what they are talking about and I am by no means an expert on everything.
> 
> As for this thread, I am done. If the threadstarter wants to email me directly thats fine too I will gladly help them setup either.


I'll give you credit for being able to cut and paste. And I'd still love an explanation on how a given "waveform" is longer in a home as compared to in a car.



AudioDave said:


> I dont use home audio for anything other than just what its for. Home audio especially surround is not even the same dynamic as Car. The acoustics are different, *waveforms are larger *thus do not cancel out as fast, there is more coloration in car and so on.
> 
> There are several test and demo discs availiable for both home and car audio. In addition, home audio is more for SQL. I have not heard of someone not on drugs putting 20K watts and 50 15" subs in a home. Its just not the same.


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## AudioDave (May 30, 2010)

ChrisB said:


> Yet another failed attempt at plagiarism by AudioDave. Wow, just wow...


Jesus guys I am supposed to type everything out to help disprove something? Wasnt plagarism I dont care what you think.


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## AudioDave (May 30, 2010)

MiniVanMan said:


> Noooo, I REALLY want to hear how a Linkwitz-Riley time alignment filter works. What the **** is Linkwitz-Riley time alignment??
> 
> So, you're telling me that you're going to tell me how to use a L/R, or Butterworth filter to correct phase shift? What does filter alignment have to do with phase shift. Slope order has to do with phase shift. Alignment has nothing to do with it. A 12db electrical filter, whether it be L/R, Butterworth, Bessel, or whatever alignment you want, WILL have a 180 degree phase shift.
> 
> ...


It was answering this wuestion. I dont have time to sit on here and argue all day, thats why I went to get the info. Who cares how it was done. It wasnt to plagarize anything get off your high horse.


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## MarkZ (Dec 5, 2005)

AudioDave said:


> Jesus guys I am supposed to type everything out to help disprove something?


Sure, why not? I did it. Minivanman did it. You posted this long thing that didn't even address the points he made. Part of the beauty of creating your own posts is that you can address what an individual asks or comments on, rather than providing a generic description.



> Wasnt plagarism I dont care what you think.


It came off that way. No quotations, no citations, not even a "here's what I read:". It was sandwiched in between your writing. 

You should go back and edit your post.


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## Knobby Digital (Aug 17, 2008)

Interesting how in both links he lifted, all references to graphs were carefully left out.

Filter & Crossover Types for Loudspeakers — Reviews and News from Audioholics

Yet, there's no time to explain....


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## ryan s (Dec 19, 2006)

Plagiarism aside (cause that's exactly what it was, whether Dave is intelligent enough to recognize it or not  ), the link to Rane's site that Gary posted reference to the stolen text was AWESOME. I think I figured out why I've got a "ringing" noise right at my mid's crossover point. Butterworth lowpass! +3dB peak at the XO point. Right between 2 params of my EQ. Eureka.

It would have driven me crazy trying to mess with it in futility...it's the crossover. At least I hope that's the problem. GOT to be, since the science is right there.

Still trying to push through the article...it's a lot to absorb. But worth it. Also a very fine link to Audioholics, when read in full and not copy-pasted


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## MiniVanMan (Jun 28, 2005)

ryan s said:


> Plagiarism aside (cause that's exactly what it was, whether Dave is intelligent enough to recognize it or not  ), the link to Rane's site that Gary posted reference to the stolen text was AWESOME. I think I figured out why I've got a "ringing" noise right at my mid's crossover point. Butterworth lowpass! +3dB peak at the XO point. Right between 2 params of my EQ. Eureka.


The +3 db peak at the crossover point only exist if there is no underlap of the crossover. 

The two alignments that we come in contact with the most are the Butterworth and the Linkwitz-Riley. Now a Butterworth will have the same crossover point for both the mid and tweeter. For example, a 3000 hz crossover point, utilizing a Butterworth alignment will be set at 3000 hz low pass, and 3000 hz high pass. That's why you get the +3 db at the crossover point. The drivers are summing. Now add in the fact that you have a parallel electrical circuit at that point, you can add another 3 db for a total of 6 db at the crossover point.

Now a Linkwitz-Riley (L/R) alignment is essentially an underlap of the crossover points to achieve a flat response across the crossover point. 

Now, here's an issue I have with active filters and the designation of various alignments. If you have a separate dial for high pass and low pass, you don't actually have any particular alignment. If you have a single selection of crossover point, then you can designate L/R or BW, given the design of the filter. In a car, it's important to note, and I guess this is true in any audio medium, but actually critical in a car is understanding the difference between acoustic and electrical slope.

In a car, you can practically throw the concept of electrical slope out the window. We're trying to achieve proper acoustic slope. Acoustic is what we hear. Electrical only gets us close. Acoustic takes into account alignment of the driver (axis response), and roll off of the frequency response. We can have a 12 db electrical slope and actually have a 24 db acoustic slope. 

It is common to designate a single high pass or single low pass, that is independent as a Butterworth filter, but for it to be a true Butterworth network, where you have summing, you need the adjacent filter to be present as well (low pass if the first filter is high pass, and vice-a-versa). 

For the problem of ringing, it would be good to know what you're using as a crossover network. If it's software driven, the lack of phase shift is a very common issue that causes ringing. Especially, if you're brick walling the filter (very high slope). Another issue could be if there are multiple phase shifts around the crossover point. You'll get this if you run a tweeter very close to Fs with a high order slope. The steep rise in impedance plays havoc with the phase shift. It's accentuated by summing as in a Butterworth, but can still be present in a L/R filter. The ringing may not be audible in many cases, due to the fact that people that like to run tweeters close to Fs, with say a 24 db L/R slope will not be pushing much power anyway. 

What are you using as a crossover? Let's start there.


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## MarkZ (Dec 5, 2005)

MiniVanMan said:


> Now, here's an issue I have with active filters and the designation of various alignments. If you have a separate dial for high pass and low pass, you don't actually have any particular alignment. If you have a single selection of crossover point, then you can designate L/R or BW, given the design of the filter. In a car, it's important to note, and I guess this is true in any audio medium, but actually critical in a car is understanding the difference between acoustic and electrical slope.


Wait. That's not really true. A L-R filter differs from a Butterworth in the Q of the filter. That's why you get the +3dB hump with the Butterworth when you set the filter points equal. They're different filter designs.


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## MiniVanMan (Jun 28, 2005)

MarkZ said:


> Wait. That's not really true. A L-R filter differs from a Butterworth in the Q of the filter. That's why you get the +3dB hump with the Butterworth when you set the filter points equal. They're different filter designs.


Yes. Maybe I didn't explain it well enough. I avoid using terms like "Q" because they're somewhat vague, and quite difficult to understand for people just cutting their teeth.

The Q of the filter is achieved when the two drivers sum. The "Q" is set at the crossover point and is a function of the summing. When you have independent control over your high pass and low pass, you can set your own "Q". You can underlap, overlap, lapdance, whatever. Giving a designation as a L/R filter is misleading because you can arbitrarily change the Q of the filter just by overlapping, or underlapping? Clear as mud?

In other words, you're right, but I was just explaining how many commercial, active crossovers can be misleading. Just because it says L/R on the box doesn't mean you're achieving a true L/R filter.


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## ryan s (Dec 19, 2006)

I'm using a Planet Audio HVT754 4 channel, currently bridged to the midbasses since one channel needs repair. 

The highpass for the midbasses is via the headunit, Pioneer 860MP, 12dB slope, type unspecified. Lowpass is on the amp, 18dB slope. High pass for the 3"ers is via another amp for the moment.

3" fullrange high passed at 410Hz (Fs is 110Hz, I believe)
Midbasses bandpassed from 63-410Hz

From the manual:


> [T]he four channel amps ha[ve] three sets of crossovers, two high pass and an 18 dB/octave low pass. Of course, all are independently adjustable.
> ...
> All crossovers are infinitely variable types, using Linkwitz Riley and Butterworth responses where appropriate.


Also T/A is being used via the headunit. The ringing is only happening in the midbass as far as I can tell. It's incredibly loud, though, so maybe I'm hearing it wrong.

The low pass on the amp is only adjustable to 500Hz. I was thinking of bumping the low pass down to around 350Hz, and maybe high passing the 3"ers a little higher, or leaving them at 410Hz. Bad weather today so I couldn't mess around.

Gah, should have made my own thread :mean: I am following along (believe it or not :laugh: ), it's just hard to describe the sound and frequencies without measurement tools.


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## AudioDave (May 30, 2010)

ryan s said:


> Plagiarism aside (cause that's exactly what it was, whether Dave is intelligent enough to recognize it or not  ), the link to Rane's site that Gary posted reference to the stolen text was AWESOME. I think I figured out why I've got a "ringing" noise right at my mid's crossover point. Butterworth lowpass! +3dB peak at the XO point. Right between 2 params of my EQ. Eureka.
> 
> It would have driven me crazy trying to mess with it in futility...it's the crossover. At least I hope that's the problem. GOT to be, since the science is right there.
> 
> Still trying to push through the article...it's a lot to absorb. But worth it. Also a very fine link to Audioholics, when read in full and not copy-pasted


Fine Ill just post links then. Was just to save him time not to copy guys sheesh.


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## AudioDave (May 30, 2010)

MiniVanMan said:


> Yes. Maybe I didn't explain it well enough. I avoid using terms like "Q" because they're somewhat vague, and quite difficult to understand for people just cutting their teeth.
> 
> The Q of the filter is achieved when the two drivers sum. The "Q" is set at the crossover point and is a function of the summing. When you have independent control over your high pass and low pass, you can set your own "Q". You can underlap, overlap, lapdance, whatever. Giving a designation as a L/R filter is misleading because you can arbitrarily change the Q of the filter just by overlapping, or underlapping? Clear as mud?
> 
> In other words, you're right, but I was just explaining how many commercial, active crossovers can be misleading. Just because it says L/R on the box doesn't mean you're achieving a true L/R filter.


This was also the point of what I posted.


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## MiniVanMan (Jun 28, 2005)

ryan s said:


> I'm using a Planet Audio HVT754 4 channel, currently bridged to the midbasses since one channel needs repair.
> 
> The highpass for the midbasses is via the headunit, Pioneer 860MP, 12dB slope, type unspecified. Lowpass is on the amp, 18dB slope. High pass for the 3"ers is via another amp for the moment.
> 
> ...


Disable the crossover. Does the ringing still occur?

If it happens at just about any crossover point, then it might be the filter itself being faulty. I don't have a cheap solution, but you could try using an inductor and see if you still have ringing.

Is it happening with both mids? 

I'm inclined to think the internal filter on the amp is faulty.

Underlap the crossover points and see what you get.


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## MarkZ (Dec 5, 2005)

MiniVanMan said:


> Yes. Maybe I didn't explain it well enough. I avoid using terms like "Q" because they're somewhat vague, and quite difficult to understand for people just cutting their teeth.
> 
> The Q of the filter is achieved when the two drivers sum. The "Q" is set at the crossover point and is a function of the summing. When you have independent control over your high pass and low pass, you can set your own "Q". You can underlap, overlap, lapdance, whatever. Giving a designation as a L/R filter is misleading because you can arbitrarily change the Q of the filter just by overlapping, or underlapping? Clear as mud?
> 
> In other words, you're right, but I was just explaining how many commercial, active crossovers can be misleading. Just because it says L/R on the box doesn't mean you're achieving a true L/R filter.


No, I don't think you understood my point. Nevermind multiple filters for a minute. If you have one filter applied to one speaker, the shape of the response will mostly be determined by the slope and the Q. It's this difference in shape that ultimately results in the +3dB hump for Butterworth but no hump for L-R when you put multiple drivers together. In both cases, the filter settings for HP and LP are 300Hz, but the hump occurs because the rolloff is sharper for the Butterworth filter.

Check out this graphic:










You can see the shapes are different (not a great illustration of my point because the crossover points are weird, but you can still see the difference in shape).


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## MiniVanMan (Jun 28, 2005)

MarkZ said:


> No, I don't think you understood my point. Nevermind multiple filters for a minute. If you have one filter applied to one speaker, the shape of the response will mostly be determined by the slope and the Q. It's this difference in shape that ultimately results in the +3dB hump for Butterworth but no hump for L-R when you put multiple drivers together. In both cases, the filter settings for HP and LP are 300Hz, but the hump occurs because the rolloff is sharper for the Butterworth filter.
> 
> Check out this graphic:
> 
> ...


I'm of the mind now that it's impossible to explain without the use of that handy dandy little graph you have. I know what you're trying to convey now, and it makes sense.

We're saying the same thing actually, but arguing semantics. I'm just saying that in order to get the true characteristics of a particular filter type, you need the congruent speaker to be filtered appropriately as well. I just woke up, so my head's a bit groggy, but I don't know how to say it any simpler.

You're pointing out the individual characteristics of the slopes, and I'm trying to point out that the overall response is a sum of it's parts. You and I do this a lot. Usually, it's political though.


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## MarkZ (Dec 5, 2005)

Haha that means progress, right?


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## ryan s (Dec 19, 2006)

MiniVanMan said:


> Disable the crossover. Does the ringing still occur?
> 
> If it happens at just about any crossover point, then it might be the filter itself being faulty. I don't have a cheap solution, but you could try using an inductor and see if you still have ringing.
> 
> ...


I'll give everything a shot once I put the amps back in the car :laugh:

I have another identical amp in the mail (accidentally bought it  ) so I can test them side by side before sending the known-faulty one for service.

I didn't check to see if it was both mids...it's definitely on the driver's side, however. The faulty channel was on the passenger side, and has an audible noise at low volume and alternator whine when the car is running. 

So I'll have to "get back to you" on the settings :laugh: Definitely a helpful thread, thanks guys


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## MiniVanMan (Jun 28, 2005)

MarkZ said:


> Haha that means progress, right?


Yeah, I've never harbored any ill will toward any of your opinions. I've just been content in knowing that you're wrong. 

J/K

Nah, I've always believed that we have sort of the same fundamental core values, but through interpretation, and individual presentation we confuse ourselves, and thus the issues.


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