# Aperiodic Enclosures in doors



## ErinH (Feb 14, 2007)

I did some searching and found this has been discussed in a few threads here already, but I really didn't get as much out of them as I'd hope to. 


I've just done some reading for the past hour or so on AP installs. In a nutshell it seems that drivers under a certain Qts are candidates for this type of install. Just so happens my Dyns fall under this 'magic' number. It looks like the idea is pretty simple: build a very small enclosure over the driver, and at the back of the enclosure use some sort of membrane (fiberglass, etc, or the Scan vents) to restrict flowrate. Amount will vary so this is a trial and error process. This makes the IB install more like sealed, correct? Which should help with control of the cone's throw, correct? 

Another thing I wonder involves the purpose of building AP which is to get rid of the impedance spike, and I could use some clarification on this... in situations where you have a device such as the h701, do you REALLY benefit from building an AP enclosure? Could the spike not be tuned out? I know you really want to get the install licked, but if you already have things installed would it make much sense to go back and do AP? I just did a search *after typing this section* and saw where Dang actually says what I just asked... Still, I'd like more opinions than just his. 

^ Is there an added benefit within getting rid of the impedance spike? If I understand correctly, impedance spike basically sucks out power and acts like a cut in an EQ b/c higher resistance results in lower power (ohm's law).

Now, regarding build... how would you do this and still get the driver back inside the door? The easy way would be to remove the deadener I have on the access hole and try to squeeze it in there... assuming the window motor brackets aren't in the way. But, for now, let's assume I can't (don't want to) remove the seal... any ideas? Could you build this up on the driver itself via a ring & fiberglass, then insert it all as one unit into the door and just bolt it in place? Any suggestions?

I don't know if what I've said above is correct. It's just what I've gathered over the past hour doing some reading. FWIW, I'm not set on building AP. I'm not sure it would be suited for me, or if it would really improve anything for me. BUT, I figured it's at least worth discussing for my own knowledge. Maybe give the forum a break of 'which sub should I buy'.


----------



## Mic10is (Aug 20, 2007)

use a tupperwear container or fiberglass some XTC baffles, anything to act as an enclosure. install AP membrane on the backside.
you can use a variovent which will work fairly well, but tuning your own AP material will work best.
Basically you are just going to play from about 20-150hz tones or so and measure the impedance at that freq. and plot the measurements. add or remove insulation to your membrane until you have a relatively flat impedance curve.

you could, make a ring baffle and do the AP membrane on the front of the driver but it can also cause some tonal coloration into the cabin, so best to do it on the backside


----------



## ErinH (Feb 14, 2007)

any other input? not necessarily on the build up of one... but the use.


----------



## Mic10is (Aug 20, 2007)

there really isnt a major necessity for AP use anymore. at one time when there were not many speaker manufacturers in the 12v industry, most used home or Pro drivers which require very large enclosure, so to control the cone movement and achieve a flatter response they went AP>

now in days, everyone makes drivers very suitable for IB configuration and if one company you are loyal to doesnt make one, which is unlikely, then I am sure another great company does.

another benefit of an AP enclosure is the "coolness' factor especially for competitiors, its a way to sell the install as going above and beyond what is required.


----------



## pyropoptrt (Jun 11, 2006)

http://www.teamaudionutz.com/tutorial/1/AP_Enclosures-The_Aperiodic_Cookbook


----------



## pwnt by pat (Mar 13, 2006)

when I was trying to design an AP vent for my doors, I created removable pods that bolted to the door. The ap mat was added inside the pod. Woofer mounted to the pod.

You could put mat in front of the woofer, but that would be the same as putting wax paper over a flashlight.


----------



## ErinH (Feb 14, 2007)

pyropoptrt said:


> http://www.teamaudionutz.com/tutorial/1/AP_Enclosures-The_Aperiodic_Cookbook


Saw that already.


----------



## GlasSman (Nov 14, 2006)

Mic10is said:


> there really isnt a major necessity for AP use anymore. at one time when there were not many speaker manufacturers in the 12v industry, most used home or Pro drivers which require very large enclosure, so to control the cone movement and achieve a flatter response they went AP>
> 
> now in days, everyone makes drivers very suitable for IB configuration and if one company you are loyal to doesnt make one, which is unlikely, then I am sure another great company does.
> 
> another benefit of an AP enclosure is the "coolness' factor especially for competitiors, its a way to sell the install as going above and beyond what is required.


PERFECT.


----------



## Hernan (Jul 9, 2006)

I have some problems with doors resonances.
I'm thinking on building an AP enclosure venting to the door.
Will the AP membrane absorbe some energy and lessen the backwave going into the door?


----------



## ErinH (Feb 14, 2007)

I actually wondered the same last night.

My midbasses are just too powerful for my door. What's more is that the shape of my door panel literally prohibits me from building onto my doors anymore to sturdy them up.

I'm starting to wonder if an aperiodic enclosure would give me the same or better results, but without the stored energy inside the door.


----------



## 03blueSI (Feb 5, 2006)

I am hoping to go with an aperiodic setup when I finish my install. The reason I am considering it is for 2 reasons. First, the speakers I am looking at, scan 18w, is a paper cone and most would say better suited to AP than IB use. Therfore, I will protect the speaker somewhat from the elements and get better low end performance from it. If I do it any time soon I will post pics.


----------



## SQCherokee (Mar 5, 2008)

I've thought about doing ap for my mids in my kicks....but the thing about the tupperware bowl with the mat on the back...that sounds like a great idea.


----------



## 03blueSI (Feb 5, 2006)

SQCherokee said:


> I've thought about doing ap for my mids in my kicks....but the thing about the tupperware bowl with the mat on the back...that sounds like a great idea.


I was planning on doing the same thing, but with the XTC foam baffles. Cutting it off just deep enough for the midbass driver and adding metal grill and sandwiching the fiberglass insulation to the back and glassing the whole setup to be stiffer.


----------



## Aaron'z 2.5RS/WRX (Oct 24, 2007)

I was going to bring this up the other day and ran out of time... 

An AP "mat" in the door would be terrible, mostly uses fiberglass for the matting and it absorbs water.... BUT, there is hope.. 

I was doing some research into AP enclosures and found one that may work for you... 

Plate style AP... 

Basically you have an enclosure, you cut a hole in it, say rectangular, then you cut a plate, one that is large than the hole by say 1" all around (i'm not going off any actual build expirence, and the research is OLD now) 

you suspend the plate over the hole with some sort of stand off, devising a way to make this adjustable would be best to allow for tuning... 

Then you simply tune by moving the plate closer/farther from the hole... 

You will still properly restrict the airflow at certin frequencies and not at others.. 

Other than the idea, I haven't got anything else for ya man, sorry...


----------



## HondAudio (Oct 19, 2006)

03blueSI said:


> I was planning on doing the same thing, but with the XTC foam baffles. Cutting it off just deep enough for the midbass driver and adding metal grill and sandwiching the fiberglass insulation to the back and glassing the whole setup to be stiffer.


Me too.


----------



## ~thematt~ (Sep 14, 2007)

Aaron'z 2.5RS/WRX: Whilst that sounds like a great idea, the purpose of an AP vent is to convert acoustic energy into heat, which I dont see that doing...?


----------



## Mic10is (Aug 20, 2007)

another way to do it is the way Anthony Davis did in his contour. His kicks are vented to the outside through a series of small holes.
I think they used 1/8" or 1/4" holes. basically drilled a hole. checked the response. Drilled another, checked response, until they have the desired response


----------



## Dangerranger (Apr 12, 2006)

Personally if I were attempting to run a low Qts subwoofer IB, I'd do it the easy way and do a resistively damped setup. Take a DVC subwoofer, put a potentiometer on the second lead, increasing resistance of the second coil allows you to vary (raise) the Qts of the driver to a value that gives you better IB performance from a subwoofer. Increasing resistance can allow you to nearly double the nominal Qts of a driver using this method. It cuts the thermal power handling of the driver by ~25%, but I feel that's pretty proportional to the mechanical power handling cut you get by running IB anyway. On top of that, AP cuts efficiency as does running resistively damped, maybe not quite as much but I consider the flexibility of resistively damped operation to make up for that and more.


----------



## Foglght (Aug 2, 2007)

Dangerranger said:


> Personally if I were attempting to run a low Qts subwoofer IB, I'd do it the easy way and do a resistively damped setup. Take a DVC subwoofer, put a potentiometer on the second lead, increasing resistance of the second coil allows you to vary (raise) the Qts of the driver to a value that gives you better IB performance from a subwoofer. Increasing resistance can allow you to nearly double the nominal Qts of a driver using this method. It cuts the thermal power handling of the driver by ~25%, but I feel that's pretty proportional to the mechanical power handling cut you get by running IB anyway. On top of that, AP cuts efficiency as does running resistively damped, maybe not quite as much but I consider the flexibility of resistively damped operation to make up for that and more.


Isn't this somewhat similar to bi-amping a DVC sub? Just vary the amount of power allowed to one coil. Me heard that not so good idea, but you seem to know about this, so I will subscribe to your magazine.


----------



## ErinH (Feb 14, 2007)

Dangerranger said:


> Personally if I were attempting to run a low Qts subwoofer IB, I'd do it the easy way and do a resistively damped setup. Take a DVC subwoofer, put a potentiometer on the second lead, increasing resistance of the second coil allows you to vary (raise) the Qts of the driver to a value that gives you better IB performance from a subwoofer. Increasing resistance can allow you to nearly double the nominal Qts of a driver using this method. It cuts the thermal power handling of the driver by ~25%, but I feel that's pretty proportional to the mechanical power handling cut you get by running IB anyway. On top of that, AP cuts efficiency as does running resistively damped, maybe not quite as much but I consider the flexibility of resistively damped operation to make up for that and more.


We're not talking about subwoofers, though...


----------



## Aaron'z 2.5RS/WRX (Oct 24, 2007)

~thematt~ said:


> Aaron'z 2.5RS/WRX: Whilst that sounds like a great idea, the purpose of an AP vent is to convert acoustic energy into heat, which I dont see that doing...?


The purpose of AP is to restrict flow on certin areas and allow flow in others... 

You are creating a "leaky" enclouser... much like a ported box, but in a wider range of frequencies.. 

Converting energy to heat, is a byproduct of the mat, moving the fibers at all the frequencies, simply creates heat, again as a byproduct... 

Please correct me if I am wrong...


----------



## Dangerranger (Apr 12, 2006)

Foglght said:


> Isn't this somewhat similar to bi-amping a DVC sub? Just vary the amount of power allowed to one coil. Me heard that not so good idea, but you seem to know about this, so I will subscribe to your magazine.


This method the second coil is terminated with a potentiometer and only the first coil is driven by the amplifier. It is essentially a shorting resistor, using electrical braking to alter the Qts of the subwoofer. 

More info with formulas to implement it on this link:

http://stereointegrity.com/Files/RDOOperation.pdf


----------



## mghunt (Jun 26, 2007)

Basically the AP mat adds resistance to air flow. It allows you to run a less than ideal driver in an "IB" setup.

If you have a subwoofer with a Q that is very low installed in a car, the low frequency response is almost overbearing due to cabin gain. In my experience, the AP mat allowed me to install a less than optimal driver (low Q) in an "IB" setup. This reduced the boominess of the lower octaves and I still got the great control. It seemed that the power handling also went up.

I am currently running some low Q midbasses in my car and I've thought that I want to try an AP setup in my door. I want to be able to drive them a little harder. I think adding some resistance behind the midbasses will help to eliminate the impedance spike at resonance. Another added benefit is that the mat can absorb backwaves. Too bad I'm already using all of my available mounting depth.


----------



## michaelsil1 (May 24, 2007)

Did anyone follow through with this and did it do what you wanted?

I need to do something and I don't have the room to seal the Mid Bass in the doors.


----------



## 60ndown (Feb 8, 2007)

michaelsil1 said:


> Did anyone follow through with this and did it do what you wanted?
> 
> I need to do something and I don't have the room to seal the Mid Bass in the doors.


----------



## michaelsil1 (May 24, 2007)

60ndown said:


>


Luke,

You've grown a beard.


----------



## ErinH (Feb 14, 2007)

michaelsil1 said:


> Did anyone follow through with this and did it do what you wanted?
> 
> I need to do something and I don't have the room to seal the Mid Bass in the doors.


I did. I have great results. My biggest issue was sealing up the dash because I was getting some cabin gain. That's car dependent, though.


----------



## Boostedrex (Apr 4, 2007)

IIRC, you pretty much want as small of an enclosure as possible for an AP setup right?

Erin, are you still liking your AP setup as much as you did when you first got it in? I've been debating going with an AP setup in my doors with the twin midbass drivers just for the "being different" factor. The pods will be bolted to the door and I could AP vent them into the door cavity through the stock speaker hole. The pod's volume would be very small if I did it this way though. 

Zach


----------



## ErinH (Feb 14, 2007)

Boostedrex said:


> IIRC, you pretty much want as small of an enclosure as possible for an AP setup right?
> 
> Erin, are you still liking your AP setup as much as you did when you first got it in? I've been debating going with an AP setup in my doors with the twin midbass drivers just for the "being different" factor. The pods will be bolted to the door and I could AP vent them into the door cavity through the stock speaker hole. The pod's volume would be very small if I did it this way though.
> 
> Zach


As far as I know, yes, you’re correct. Or, maybe you don’t have to have a small enclosure, but my understanding is the purpose of an AP enclosure is to be used on enclosures that are too small to get the ‘normal’ response out of them. Tuning is all in the mat. I read stuff and forget it quickly, so you might want to check on that…

Yes, I’m actually liking it more that I’ve gotten the cabin gain/standing waves/whatever issue scaled down. This is all car dependent, though, so you might not have issues at all. Especially if you consider mine were essentially corner loaded. I’m still tuning on them. I’m still learning. 

Make sure your panels are dead, or are separated from any points it can rattle on. Especially if you’re wanting to cross them low. That’s one of the big reason I wanted to get them out of the doors. 

FWIW, I now keep mine crossed at 50hz and they do very well. I had them at 40hz at one point, but that was sacrificing the overall output as I couldn’t put them as loud as I had wanted. But, for most listening, they did just fine even that low.


----------



## Boostedrex (Apr 4, 2007)

That's one thing I'm happy about, I have ZERO door panel rattles. But that is also just a single 6.5" per door. It is with a 63Hz HP and as much volume as I want.  

I may try out the AP thing just for S-n-G's. If I don't like it then I'll cut out the AP vent and let the pod fully vent into the door cavity. I guess I can't lose out either way other than some extra time until project completion. Does that sound about right to you too?

Zach


----------



## PaulD (Nov 16, 2006)

I did too, they are in the floor. A bit unorthodox but they work out pretty well.


----------



## ErinH (Feb 14, 2007)

Yea… just wait until you get a speaker in an enclosure… it’ll take more power and will be able to play lower. Those rattles will show up. 

Go for it. As long as you get the right speaker and tune the enclosure correctly, you’ll be very happy.


----------



## michaelsil1 (May 24, 2007)

So the big thing about Aperiodic is the amount of stuffing?

Did anyone go with the Dynaudio or Scan Speak rear baffle?


----------



## Boostedrex (Apr 4, 2007)

I think that Erin's enclosures use the Scan variovents.


----------



## ErinH (Feb 14, 2007)

michaelsil1 said:


> So the big thing about Aperiodic is the amount of stuffing?
> 
> Did anyone go with the Dynaudio or Scan Speak rear baffle?


Just to make sure, you know that the ‘stuffing’ is the stuffing in the vent, right? Not talking about just stuffing an enclosure with polyfill. You actually tune the vent via stuffing/insulation, or you buy the scanspeak variovents (madisound sells these).



Boostedrex said:


> I think that Erin's enclosures use the Scan variovents.


Yep


----------



## michaelsil1 (May 24, 2007)

Boostedrex said:


> I think that Erin's enclosures use the Scan variovents.


Cool. 

Did he do the Tupperware deal or opt for fiberglass?


----------



## Boostedrex (Apr 4, 2007)

Custom made floor/kick panel AP enclosures made by a local installer. Beautiful work from the pics I saw of them.


----------



## michaelsil1 (May 24, 2007)

bikinpunk said:


> Just to make sure, you know that the ‘stuffing’ is the stuffing in the vent, right? Not talking about just stuffing an enclosure with polyfill. You actually tune the vent via stuffing/insulation, or you buy the scanspeak variovents (madisound sells these).
> 
> 
> 
> Yep



Yeah, stuffing for the rear vent that's why I was asking about the Scan or Dyn.


----------



## ErinH (Feb 14, 2007)

michaelsil1 said:


> So the big thing about Aperiodic is the amount of stuffing?
> 
> Did anyone go with the Dynaudio or Scan Speak rear baffle?





Boostedrex said:


> I think that Erin's enclosures use the Scan variovents.


My bad. Didn’t even see the last sentence about that.


Yea, my kicks were made by Steve Cook of Audio X in Florence, Al. He did an awesome job. I had toyed with doing it myself but I know it would’ve taken me forever and probably as much money (time = money) if I had.


----------



## Boostedrex (Apr 4, 2007)

Hey Erin, what's the diameter of those Scan vents??


----------



## ErinH (Feb 14, 2007)

think 4", iirc.

http://www.madisound.com/catalog/product_info.php?products_id=1323


----------



## Boostedrex (Apr 4, 2007)

So what specs make a driver well suited for AP use? Here are the pertinent specs for the drivers that I'm using.

Vas= 12.361 Ltr 
Cms= 479.205u M/N 
Mmd= 12.505 g 
Mms= 13.405 g 
BL= 5.884 TM 
Qms= 6.974 
Qes= 0.489 
Qts= 0.457 
Xmax= 6.5mm


----------



## ErinH (Feb 14, 2007)

Boostedrex said:


> I think that Erin's enclosures use the Scan variovents.


there's a great tutorial audionutz wrote. matter of fact, didn't I send you that link?...

here it is if not:
http://www.teamaudionutz.com/tutorial/1/AP_Enclosures-The_Aperiodic_Cookbook


----------



## michaelsil1 (May 24, 2007)

bikinpunk said:


> there's a great tutorial audionutz wrote. matter of fact, didn't I send you that link?...
> 
> here it is if not:
> http://www.teamaudionutz.com/tutorial/1/AP_Enclosures-The_Aperiodic_Cookbook


I think this link is near the beginning of this thread. 

I'm definitely a candidate for AP, I have home Audio Drivers (SEAS W18NX) and a low QTS.


----------



## Boostedrex (Apr 4, 2007)

bikinpunk said:


> there's a great tutorial audionutz wrote. matter of fact, didn't I send you that link?...
> 
> here it is if not:
> http://www.teamaudionutz.com/tutorial/1/AP_Enclosures-The_Aperiodic_Cookbook


That was a very good read. I saw it earlier in this thread too, but hadn't read it until tonight. The only problem is that he only addresses AP boxes for subs and how they can negatively affect sub Hz response. That doesn't nearly as much for a midbass. So what are the drawbacks to using AP for dedicated midbass??


----------



## PaulD (Nov 16, 2006)

The only real drawback is you lose some efficiency


----------



## Boostedrex (Apr 4, 2007)

That's not going to be a problem Paul. I have pretty decently efficient midbass drivers to start with and WAY more than enough power to spare. Anything else?


----------



## sqshoestring (Jun 19, 2007)

Take it for what its worth, I did a lot of this in the past. I would use those foam baffles you put behind the driver in a door to protect it. Simply cut holes in the bottom of it to vent, more and more until you have the bass you need. Tape them up to tighten. This was done to increase power handling/limit excursion. All you get is less bass. Today I use a crossover/EQ to do that and get less loss of efficiency. It was not often I hit a car that had so much cabin gain one wanted to do it on subs, if so then you could run more power and get louder by AP'ing out the lowest bass. I did the same thing with subs, used felt mostly, close to the sub. Sometimes carpet on a rear deck was enough, carpet and felt worked over mids in doors too (in grill/hidden/etc). IMO you just limit excursion partially like a sealed, you lose bass...not what I want in a car since I don't often over power my systems. I found it more effective in doors, but modern cars tend to have poorer door bass than older larger cars so I don't do it much anymore. If you want to get an idea of what it does just duct tape the back of the speaker 75% shut and try it, adjust air flow. You have to do better on high excursion drivers but even just the tape works fine on say 40wrms door speakers that bottom at small xmax. They will still bottom if you send very low frequency to them, a sealed enclosure works better for that. Way back I'd use a big cap on them to help that, if I did not have a crossover to do it. A lot of old crossovers are really noisy so I tended to use one for sub split and passive for highs...resistors to attenuate highs. Lately I find a parametric is the bomb on IB bass drivers, I can make them sound any way I want with limited mechanical tuning. I wish someone made a parametric you could run on just subs, just 10-200Hz, or maybe two in one to cover midbass also. The one I have includes an EQ that makes it large, I'm thinking double the size of a bass knob or so. Some day I'll find a HU with parametric in it.

So I guess if you really need to tighten them up it will work that way, I prefer to use electronics now if I can get away with it. The rears in my car right now are coax I tossed in there primarily for out of car use. I just duct taped them because they are only 40-50wrms drivers and they would bottom. It helped them a lot, still are crossed at 100+ Hz. But when I put them in I ran them parallel to fronts that were crossed lower.


----------



## soundq1 (May 18, 2008)

I have the best luck with free air in the door locations.

Larry C


----------

