CW II cabinet, to stuff or not to stuff?

[Steve Smiley]

Hello,

I'm starting work on a Klipsch project, my first. Been tied up in Bozak and Econowave . A friend has asked for some help with his Klipsch Cornwall II. I am refreshing his original pair and building (DIY) another set for his large rec room. He had the horns, I'm providing the woofers...

Anyway, the CW II has non removable baffle and rear panel, making it less than ideal for working on the internals. But I do want to add some more bracing and I'm wondering if the cabinet needs some dampening/lining. I see the original CW has what looks like a cotton batting installed.

Any recommendations for me? Yeah or nay, to stuff or not to stuff? Most of what I know says "yes,” to lining at least one side of each parallel side; say top, side, and rear panel.

Anyone have thoughts on tackling this question and what material would you recommend? I have some cotton batting from futon mattresses. Also have some fibergalss insulation ready to go if that is the ticket,

Thank you for any feedback.

I always thought I would dabble in Klipsch. PWK history certainly intrigues me.

I picked up a Peavey FH-1 and I have a few horn choices - including Altec 511B, EV HR6040, maybe an EV HP series (Still need to confirm) for some La Scala-like experimentation.

Regards,

Smiley

 

[Chorus1fan]

https://www.amazon.com/Level-Pack-A...gg+Crate+2"+X+12"+X+12"&qid=1617364538&sr=8-1

I like to use this stuff, & glue it to the upper sides & top, but you want everything to be above the woofer level. If you apply it lower, the front baffles/ports don't "fire" right (diminished bass)

If you do the rear wall, same idea stay ABOVE the woofer only. It needs a hard rear surface to bounce off (& go out the front baffles/ports)

 

[twiiii]

Stuffing will reduce the woofer output making the midhorn more predominant. It will also detune the port causing further compromises.

 

[Tia]

I followed the original batting pattern using this stuff in my custom Cornwalls. Will be using the same in a set of Decorators I'm restoring.

https://www.amazon.com/Acoustic-Abs...s=sound+dampening&qid=1617731205&sr=8-37&th=1

Here is a pic of my custom CW. The shelf below the mid horn is my idea, but you can see how these acoustic panels work.

 

[grindstone]

Nice lining. FWIW, not sure how solid (or exactly how deep) the brace is, but if it's all solid, it's likely that your CW is no longer acting like a CW acoustically. It becomes another resonator/chamber.

To the OP, a cross-batt can be useful in CW. I had CW II for some years.

 

[Steve Smiley]

To the OP, a cross-batt can be useful in CW. I had CW II for some years

thank you @grindstone , I appreciate any thoughts. Can you clarify what you mean by cross-batt?

I ended up using a thinner layer of fiberglass insulation on the interior walls, above the vent. I like the results a lot. They are not bass shy. I will share that I also made some updates to the crossovers so I’m certain that contributed as well. The originals had the crossover attached to the backs of the binding post terminals I removed them and used some other original CW II crossovers that were on bread board. I also replaced the original inductors with better quality. For the replicas I am making I’m using the original auto transformer but all new inductors and caps. The following are photos of both, with the DIY crossover shown with the crossover board that was removed from the back of the terminal plate.



thank you again,

Smiley

 

[Bugetnirvana]

Stuffing will reduce the woofer output making the midhorn more predominant. It will also detune the port causing further compromises.

That is an interesting take.

Nice lining. FWIW, not sure how solid (or exactly how deep) the brace is, but if it's all solid, it's likely that your CW is no longer acting like a CW acoustically. It becomes another resonator/chamber.

To the OP, a cross-batt can be useful in CW. I had CW II for some years.

Some types of resonance I like, others not so much. I guess it kind of comes down to personal preference.

 

[grindstone]

Looks fine to me and if you like it, it's done Re the cross-batt...people who make big/tall reflex boxes sometimes end-up with unpalatable response from standing waves messing with the few-hundred Hz area. A common treatment to tone-down some of the midrange energy is to put fiberglass across the (usually mid-) braces perpendicular to the longest dimension--the "cross-batt" (of fiberglass). Small cabs still have the pipe/column resonances but dimensions push them farther out of band so they don't get excited as much. All that stuff is modelable with what's available to the diyer these years. Here's a very rough ballpark example sim of the long-dimension-damping w/ and w/o a hunk of resistive filling.

Given a box that's not to be opened again, I'd stick one on a cross-brace and let it be with what you have but that's just me and opinions vary. During development, one can lay boxes on their backs and experiment while program material plays (but using gaskets and gravity instead of messing with fasteners). Most people like a little ripple, actually--as do I.

If you weren't aware, there is a staggering amount of experience and knowledge over on Klipsch's forum, too. If you want more autoformers, you can find some at crites' site. Congrats on what I'm sure is a fine unit.

 

[uteman1011]

I just refurbed my CWII's last year and have never felt they needed dampening. I don't crank them up too much so maybe there's something I'm missing?