Just wondering if anyone has experimented with an IB setup in an frc?

seems like it'd be pretty easy way to get efficient, clean, deep bass.


I haven't given much thought to them in our cars but i was just planning out an IB setup in my house and became curious.

update:
my house project is complete:
http://forums.corvetteforum.com/show...4&postcount=57

 

IB's are an easy, inexpensive way to get small size, good, clean, undistorted bass. It is at the expense of some efficiency and low frequency extension.

 

I was just curious about an actual c5 application of an IB setup.

i didnt realize there was a low frequency extension drawback. how major are we talking? I've only ever heard on IB setup in a car and i was extremely pleased/suprised, i always thought they would sound like crap (from my limited demos at the tweeter store back east)

 

I've been curious, but have not had the guts to try it. I guess you could always try a membrane too.

 

If you're talking about the IB designs I think you are, the reason they sound awful in a showroom is because cancellation is occurring. IBs are usually left for vehicles with real trunks because the trunks are more or less isolated from the passenger compartment. The first time I recall it being done was in the Holdaway/Clark Buick in the late '80s.

Of course, that's unless there's some new configuration I'm not aware of.

 

that's why i was wondering if you could do it in a c5 frc with a partion divider that will close off the rear of the woofer from the front. it may be a good alternative for someone that wan't to save a bit of space and keep the functionality of the center storage compartment.

 

anyone have links or pics of what this baffle is?

 

I only saw a hatchback done one time (in a Honda Civic) and honestly, as well-implemented as it was, it simply wasn't worth the trouble. There was nothing about the system that couldn't be accomplished with a traditional setup with far less aggravation.

A trunk is the ideal configuration for this because you have so much more space to fiddle with the aperiodic membrane. And believe me, the membrane takes a lot of effort and electrical testing to get right. Otherwise it ends up sounding like a vented enclosure where the vent is not correct (flapping, unloading, boomy response...). It's a serious PITA and not for the faint-of-heart or those uninitiated in loudspeaker testing.

http://www.audiogearreviews.com/tech...c_membrane.asp

 

i dont have a pic off hand but just think about it this way. you have a sedan with fold down seats. you mount a board against the fold down seats isolating the trunk from the rest of the car. now you just mount the aperiodic membrane (looks like a sub w/o the motor) and a sub against that board (baffle)

 

From what I understand...

An infinite baffle is nothing more than a way to mount your sub, or perhaps better said: a type of box for your sub... the 'inside' of the box is 'infinite' in size... a very large trunk for example.

Some home theater guys use their attics as the sub enclosure, and mount the 15" IB subs in a way that isolates the attic from the room.

You don't 'buy' an infinite baffle... you build one.

You can buy an Aperiodic Membrane, however. Aperiodic membranes help provide a better transient response when using a sub in an IB configuration.

Parts Express sells them:

http://www.partsexpress.com/pe/pshow...TOKEN=93986940

Look here for more information:

http://www.audiogearreviews.com/tech...c_membrane.asp

...or just Google "Aperiodic membrane" for more information.

Hope this helps.

Mark

 

That's a whole different animal called a passive-radiator 4th order enclosure. They're VERY different things.

Two main types of infinite baffle setups:

1 - A board across the seat frame holding one or more drivers facing the interior of the vehicle with no box behind it. The trunk itself acts as the enclosure. This is a traditional "infinite baffle" setup.

2 - A sub in a box where the sub is in the passenger compartment and the back wall of the box is in the trunk and is made of a material that resists air flow. That's called "aperiodic." The membrane causes the driver to behave as if it's in a MUCH larger enclosure than it really is. Sort of like the stuffing inside a sealed box, but the effect is far larger.

In both instances the trunk MUST be reasonably sealed off from the passenger compartment.

 

Here's the Buick for those interested, including pics of the AP setup.

Speakerworks

 

oh wow i didn't know that was different. the passive radiator acts as a tuned port though, right?

 

In effect, yes, but in practice it's a lot easier to tune an actual port. I've never seen anyone try to use a passive radiator in an IB design, because by definition, the "box" in an IB design is so big as to have virtually no effect on the woofer's performance. A passive radiator has to be adjusted to account for box size, and since there's really no box....

 

i want to say that the one i did listen too had a passive...but i could be confusing it and it may have just had dual 15" IB subs.


not to take this thread totally off topic but could you take a look at this sub:
http://www.soundsolutionsaudio.com/f...howtopic=10024

I stumbled across this and was thinking about using it in an IB setup in my house for ht use. I don't want anything too crazy and this may just be a learning experience for me but It seems like the sub has some potential.

 

OK, a few issues....

1 - If you heard an IB sub in a store in a box, then you certainly didn't hear it the way it's intended. The idea behind an IB woofer is to use in a trunk without a box because the woofer has such a high Qts to start with. If you put an IB woofer in a box, you just screwed the whole thing up. Than includes anyone who uses an IB sub in a hatchback. I expect nothing less from BB/CC/Tweeter/etc.

2 - Car audio drivers don't tend to work very well in the home, unlike the reverse. Car audio drivers are designed for more of a closed-field listening environment than home drivers. The distortion characteristics of home drivers are one of the reasons they're becoming popular in cars, but not vice-versa.

3 - That particular woofer is not really anything special. Companies like that don't build drivers. They place orders for drivers build to certain parameters and from a menu of parts that result in the characteristics they desire in the final result. I've been seeing clones of that very driver for almost ten years now.

4 - For your home use: find a woofer with very low distortion numbers, high sensitivity, relatively low Vas and a moderate Qts (around 0.3-0.4), and build a box for it. Drivers that qualify are not cheap. Don't expect to get away with spending $100-200 on a quality home driver (only one exception I can think of). If you're set on an IB design in your home, look for a driver with a Qts > 0.6. And don't forget that the back of this woofer has to be in another room.

It's much easier to hear distortion in a home system than in a car system, so don't apply car audio techniques to the home. In the end, the home system can be more rewarding than the car, as long as you make good decisions.

 

they installed it on a wall correctly






time to rip open my madisound and parts express catalog. I'm not striving for ultimate sq for this one. i more or less want to get an entry level setup to play around with IB setups.

PE does have an IB 'specific' sub with low Qts. when things get a bit less crazy here i'll post a link and specs. It's a low cost driver but i'm not striving for audiophile quality sound in my house (ironic huh?) The other sub i was considering is the fi q18 that gets good reviews, it's ~$300

the back of the woofer will be in the attick.

what one qualifies :-)


this is what i'm tying to do. create a budget ht sound that will beat a htib soundquality. I'm testing two fullrangers for the sats (the zaphaudio 3" fullrange and a tang band 3" fullrange) and then the sub is my last hurdle. as you can see...not an elite system but hopefully a good sounding system that i can enjoy watching some kick *** movies.

thanks for your help so far

 

I haven't done it it my C5, but I did it in my 2nd and 3rd gen camaros, and my 93 Pontiac Grand-AM.

Oh, yeah back to the topic, I did put 12's in the first two, and a single 18" in the grandam. All three sounded great inside the car when the trunk was closed, but the bass the did not travel much outside the cars.

 

You mean they had the rear in a huge chamber or was it a display wall module?

Tonegan (Foster) 1259 http://www.madisound.com/catalog/pro...oducts_id=1402

PE is...? The nature of a low Qts woofer makes it unsuitable for IB, unless it's a strange design. I look forward to the link. If you follow Zaph's directions, you'll have a very good system for about 15% of something similar bought retail. The man knows his stuff. The sub you linked above will do IB just fine, and I meant nothing by my commentary except to say that it's not an uncommon design. The xmax looks overstated, not that xmax is all that important anyway, but...

Hey, I'm always happy to help anyone who genuinely looks for guidance, as opposed to fanboys who think brand means everything and want to argue without understanding the underlying science.

And I don't care about impressing anyone outside the car. I turned 21 19 years ago.

 

sorry i misspoke about the qts of the driver, here is the link though
http://www.partsexpress.com/pe/showd...number=295-455

pe is parts express



the subs at tweeter were mounted in the wall of the listening area (completely closed off room) and the backs of the speakers were open to the loby area