Stuffing Folded Horn Rear Woofer Chambers

[ka7niq]

What is the theory of adding or removing stuffing from the rear woofer chamber in Folded Horns.

[DrWho]

It changes the compliance of the "spring" acting on the rear of the diaphragm. Adding stuffying allows the rear chamber to act larger than it is - I'm not sure how accurate the claim is, but it's the theory. I usually just rely on stuffing as a tool to break up standing waves...

I might add that I've experimented with stuffing a bit and was able to measure the difference between smaller + stuffing versus an actually larger cabinet. The larger cabinet measured better.

[ZAKO]

This comes up several times....Do not stuff back chamber of Khorn....This changes back EMF of woofer.. it is not recommended.

[ka7niq]

It is for SpeakerLab SK's, not Klipschorns.

I looked in the chamber, and there is a bunch of Dacron Sheets in it.

I know from experience adding stuffing to a sealed woofer often tightens up the bass, and too little can sometimes make it muddy.

I wonder If possible to tune the bass a bit with the stuffing ?

The SpeakerLab SK's almost overwhelm my room with bass.

[ZAKO]

Tune the bass?? the Khorn is not a musicle instrument. What do you know that Paul Klipsch didnt know? And 60 yrs of expertise... The answere to stuffing that chamber is still NO. The SK was a wanna be that never quite made it...

[DrWho]

I know from experience adding stuffing to a sealed woofer often tightens up the bass, and too little can sometimes make it muddy.

I wonder If possible to tune the bass a bit with the stuffing ?

The SpeakerLab SK's almost overwhelm my room with bass.

How do you define "tightening" and "muddy"? Like in actual objective terms...the reason I ask is because the systems at play in a horn are different than the systems at play in say a vented cabinet or simple sealed direct radiator. Trying to apply partial systems to a completely different system isn't a "good" approach.

That said, you can certainly experiment for yourself and see how things turn out, but I have a hard time believing any sane engineer is going to overlook a simple thing like this...that's not to say that you can't make changes with it, but chances are the problem you're perceiving is something else in the system? I would start looking at other things like the room or whatever before re-engineering the speaker.

Btw, I seem to recall that the SK performed quite poorly in comparison to the Khorn...like rolling off at 100Hz or something like that? I dunno all the details, but that might be something to look into as well....so perhaps that damping shouldn't be in there (but who knows what other changes were made). I tried to do a little google searching and only caught mention of one person saying he added a sub because of their rolloff, but ya...that might seem a bit contrary to the current problem.

[ka7niq]

I have had Klipschorns in the same corners, bass was not as low, nor as powerful sounding.

In theory, what will stuffing do, or not do sonically ?

[ZAKO]

Its not theory,,,,IT WILL degrade the bass. Back EMF will change.

[colterphoto1]

Maron is still right. DON"T do it.

[Groomlakearea51]

ka7niq: Totally agree with Maron! An aquaintance had a pair of SL K'horn clones; he came over, listened to the real deal and promptly asked the same question..... I went over to visit him and found several problems. The panel seams inside the SL bin were not sealed, gaps everywhere, leaked like a sieve; we tore out the "stuffing", sealed the bin enclosure with caulking, and it was much better. Still nowhere close to a Klipschorn. Oh well he was happy. Why is/was it in there? Who knows, Maybe someone familiar with the SL clones can answer that. I did note that the bass driver inside his SL's were not of a very high quality. Maybe an attempt to compensate for the lack of LF response??

[JohnA]

Dr. Who answered your question. The stuffing makes the back
air chamber behave as though it was larger. That means the woofer
cone has less "air spring" behind it and thus is less tightly
controlled. Stuffing a chamber that is properly sized for the
woofer will change the response curve, typically biasing it a little
deeper and allowing the resonance to ring louder.

So, it might go deeper and will likely get boomier.

If you
had K-horns there and they were not as bassy, stuffing the back air
chamber will probably make the SKs even boomier and tend toward
one-note bass. I'd say you need to look HARD at your crossover
network. You are probably running the squawker and tweeter too
low.

[ka7niq]

Wow, it is just the OPPOSITE on a folded horn I see ?

Adding stuffing makes the speaker boomy, not tighter like a sealed box does when you add stuffing.

The back chamber of these has a LOT of dacron in it, and I mean quite a bit.

IS it possible SpeakerLab intended these to be tuned by adding/subtracting stuffing ?

[Islander]

Stuffing, like fiberglass batting, for example, adds "virtual volume", making the speaker box act sort of like it was larger. If the speaker was sold that way, it's likely that the engineers who designed it thought that was the optimum setup for that speaker. Adding or subtracting those materials is a way of second-guessing the designer, usually not a successful way to go.

[ka7niq]

Thanks everyone.

I removed all the stuffing, including a bunch I added.

Now it sounds like folded horn bass, no more boom.

Actually, I was getting a woofy sound on some male voices, like Barry Sadler singing Green Berets and some Cat Stevens.

That sound is almost gone now too.

I still have to re seal the woofer side doors, but I can hear the difference it makes.

These speakers have old L Pads, can they go bad ?

They still adjust, can they be cleaned with cramolin ?

I replaced crossover caps, left resistors.

Anything else to do to old horns ?

[DrWho]

Adding stuffing makes the speaker boomy, not tighter like a sealed box does when you add stuffing.

Whether or not stuffing makes a sealed box boomier or tighter is dependant on many other variables. In other words, one sealed alignment could get boomier with stuffing added while another sealed alignment will get tighter. There is no direct audible trend. The same is true for the rear chamber on horns. Stuffing on a khorn is bad while stuffing on another horn designed to have stuffing will be good.

[ka7niq]

Adding stuffing makes the speaker boomy, not tighter like a sealed box does when you add stuffing.

Whether or not stuffing makes a sealed box bomier or tighter is dependant on many other variables. In other words, one sealed alignment could get bomier with stuffing added while another sealed alignment will get tighter. There is no direct audible trend. The same is true for the rear chamber on horns. Stuffing on a khorn is bad while stuffing on another horn designed to have stuffing will be good.

Since the SpeakerLabs are Klipsch clones, and Klipsch don't want stuffing ??

I just listened to both speakers with all stuffing removed.

Bass is tighter, but I do seem to have lost a BIT of low bass.

I guess I will just have to play ?

All corner horns, actually every folded horn I have ever owned, and this includes Belle's, Horns, and La scala seem to have a folded horn woody sound for lack of a better word.

You know what I am talkin about Mike ?

A Coloration that makes Oak Ridge Boys sound like Barry White.

I am coming to conclusion no speaker is perfect, and man I love what a folded horn does otherwise.

I do have a 5 band stereo Parametric EQ, gonna hook it up and play.

It is a pro unit with variable everything

See if what Mark Levinson told me long ago is true ?

He said Klipschorns are the ultimate speakers but only with EQ, and to get the tweeters vertical for imaging.

Wonder if I can EQ out the woody sound of folded horns ?

[ka7niq]

Dr. Who answered your question. The stuffing makes the back air chamber behave as though it was larger. That means the woofer cone has less "air spring" behind it and thus is less tightly controlled. Stuffing a chamber that is properly sized for the woofer will change the response curve, typically biasing it a little deeper and allowing the resonance to ring louder.

So, it might go deeper and will likely get boomier.

If you had K-horns there and they were not as bassy, stuffing the back air chamber will probably make the SKs even boomier and tend toward one-note bass. I'd say you need to look HARD at your crossover network. You are probably running the squawker and tweeter too low.

I was told to short out my woofer inductor, so I just hooked my woofer directly up to the amplifier wires going to my crossover.

The bass improved a LOT.

These SpeakerLab SK's are old, I think a good cleaning of everything is in order.

I changed capactors, replacing them with same values and types.

Plan to get better ones, these were all radio shak had.

The crossover uses an 8 ohm resistir on the midrange and tweeter.

The guy said it is an EV t 350 tweeter, it has a big round magnet

The mids and tweet is on L Pads that were really loose.

I tighten em down, and turned all L pads 25 or more times up0 and down to9 try mechanically clean em.

Might have to replace em, maybe spray some cramolin ?

I think woofer sound better running all the way up so far.

Woody sound is becoming less and less, maybe getting used to it.

These have stronger bass then Klipschorns I had a year ago in my room.

Getting addicted to folded horn sound and majesty.

Makes my other stuff sound like toys.

[DrWho]

After hearing the Jubilee, I'm pretty much convinced that the wooden sound can be attributed to the exponential flare rate - the hollow sound goes away with tractrix. There is also the issue of discontinuities from the folds, but that mostly affects the higher frequencies.

[ka7niq]

After hearing the Jubilee, I'm pretty much convinced that the wooden sound can be attributed to the exponential flare rate - the hollow sound goes away with tractrix. There is also the issue of discontinuities from the folds, but that mostly affects the higher frequencies.

I do hear it on these speakers, but it isn't bothering me as much as it has in the past.

No speaker is perfect in every way.

The last pair of Klipschorns I had could sound like a Tuba at times.

They were used ones, pretty old too.

Maybe there was broken wood/loose woofer ?

At any rate, I am sure glad I removed all the stuffing from my rear woofer chamber.

Sure sounds better.