Corners - Superchunks or Panels?

[Rednose]

Hello, I'm putting the finishing touches on my quick and dirty guitar booth today.
I have enough 703 and birtch panels to make two 2' by 4' panels with burlap.
Should I order some more 703 to make super chunks in the corners or go ahead and hang two panels in the corners.
What are the advantages of either?
The panels would leave an air space. Is this ideal or is the super chunck method of covering from floor to ceiling better?
Thanks,
Matt
Here is a sketchup of my design.

[Ethan Winer]

Filling the space using chunks is better than panels, but only a little better. If the added material cost is not an obstacle, go for it.

--Ethan

[Glenn Kuras]

Just to clarify at 80Hz it is only a little better, but at 50hz it is over 2 times better then a 4" panel. I would go for it if you can.

Glenn

[Rednose]

Thanks Ethan!
Its for a guitar booth, so if its not going to be that much of a difference, I will save the extra coin.
BTW, I really enjoy your videos, keep them coming!
I've had the opportunity to see your traps first hand at a studio in Chicago and they look great!
Matt

[Rednose]

Originally Posted by Glenn Kuras

Just to clarify at 80Hz it is only a little better, but at 50hz it is over 2 times better then a 4" panel. I would go for it if you can.

Glenn

Thanks for the responce Glenn!
I watched your video on hanging panels in the corner and I'm going to go for it.
I'm out the door looking for some oox hooks.

Why is the air space created by the panels an advantage/disadvantage?
Thanks,
Matt

[Glenn Kuras]

Thanks for the responce Glenn!
I watched your video on hanging panels in the corner and I'm going to go for it.
I'm out the door looking for some oox hooks.

Glad it helped!!

Why is the air space created by the panels an advantage/disadvantage?
Thanks,
Matt

The air space does help, but it is all about mass, so filling the area ALWAYS does a better job.

Glenn

[Rednose]

Thanks for clarifying and best of luck with your European plant!
Matt

[Glenn Kuras]

Originally Posted by Rednose

Thanks for clarifying and best of luck with your European plant!
Matt

Thanks man.

[Ethan Winer]

Originally Posted by Glenn Kuras

Just to clarify at 80Hz it is only a little better, but at 50hz it is over 2 times better then a 4" panel.

Do you have any legit documentation that shows this?

--Ethan

[Glenn Kuras]

Originally Posted by Ethan Winer

Do you have any legit documentation that shows this?

--Ethan

Yes I do which I have sent you in the past.

[Ethan Winer]

Just to clarify, Glenn and I discussed this on the phone and (I'm pretty sure) we both agreed a bit more research is needed before we have any hard conclusions on chunks versus panels.

--Ethan

[Glenn Kuras]

Good talking to you Ethan. Yes we both agree that more research is always a good thing. But we also agree that the data that is out there shows my statement to be valid.



Glenn

[Ethan Winer]

Originally Posted by Glenn Kuras

we also agree that the data that is out there shows my statement to be valid.

I can't say you're wrong because I never tested exactly this scenario side by side in a lab. Have you?

Considering only the material sizes and placements suggests the absorption should increase maybe 20-30 percent more for filling the corner versus a 4-inch panel.

If there's valid data "out there" I have yet to see it. By valid I mean a side-by-side test of 32 linear feet of bass trapping in the exact same corners of the same lab. Any links you might have are most appreciated.

--Ethan

[jwl]

There's no question that a superchunk style trap will out-perform a 4" panel straddling the corner. The question is, how much of an improvement is there? As Ethan says, the only way to know this for sure is to test both designs in the same lab on the same day, etc. And even then, absorption tests vary highly (as much as 50% or more), especially under 100Hz, which is precisely where I'd expect the improvement in the superchunk design.

Another question is budget. If you have an unlimited budget, then definitely superchunk every corner (including wall/ceiling and even wall/floor corners).

However, if there is a limited budget, you'd be better off maximizing coverage area with 4" traps across the corners, than to use all of your material to superchunk only 1 or 2 corners.

For the OP: if you are building a guitar booth, I probably wouldn't worry too much about superchunking. Most guitars don't have much going on at 50Hz.

[Glenn Kuras]

Originally Posted by Ethan Winer

I can't say you're wrong because I never tested exactly this scenario side by side in a lab. Have you?

Considering only the material sizes and placements suggests the absorption should increase maybe 20-30 percent more for filling the corner versus a 4-inch panel.

If there's valid data "out there" I have yet to see it. By valid I mean a side-by-side test of 32 linear feet of bass trapping in the exact same corners of the same lab. Any links you might have are most appreciated.

--Ethan

There's no question that a superchunk style trap will out-perform a 4" panel straddling the corner. The question is, how much of an improvement is there? As Ethan says, the only way to know this for sure is to test both designs in the same lab on the same day, etc. And even then, absorption tests vary highly (as much as 50% or more), especially under 100Hz, which is precisely where I'd expect the improvement in the superchunk design.

Another question is budget. If you have an unlimited budget, then definitely superchunk every corner (including wall/ceiling and even wall/floor corners).

However, if there is a limited budget, you'd be better off maximizing coverage area with 4" traps across the corners, than to use all of your material to superchunk only 1 or 2 corners.

For the OP: if you are building a guitar booth, I probably wouldn't worry too much about superchunking. Most guitars don't have much going on at 50Hz.

Not sure why Ethan had to bring in back up, but so be it.

Have a great one guys.

However, if there is a limited budget, you'd be better off maximizing coverage area with 4" traps across the corners, than to use all of your material to superchunk only 1 or 2 corners.

I would agree with this statement.

[Glenn Kuras]

I can't say you're wrong

Right

[Glenn Kuras]

Ethan and JWL from Realtraps.

Jules has rules against 2 companies going back and forth. We talked on the phone so lets leave it at that. RESPECT GS

[Rednose]

I went with the coner panels. I only had 2" on hand and thats what I went for. I didn't have enough to make superchunks, so I just did what I could.
I wanted to get it done anyway, this insulation stuff is NASTY!
I used Glenn's corner panel mounting method.
I will post pix later tonight.
Thanks for the discussion!
Matt

[Glenn Kuras]

Originally Posted by Rednose

I went with the coner panels. I only had 2" on hand and thats what I went for. I didn't have enough to make superchunks, so I just did what I could.
I wanted to get it done anyway, this insulation stuff is NASTY!
I used Glenn's corner panel mounting method.
I will post pix later tonight.
Thanks for the discussion!
Matt

Well with all the back and forth talk (sorry about that) I am glad it worked out for you. If the budget is low then it was smart to go with the 4"..

Glenn

[Glenn Kuras]

Originally Posted by jwl

And even then, absorption tests vary highly (as much as 50% or more), especially under 100Hz, which is precisely where I'd expect the improvement in the superchunk design.

.

Just to clarify, labs do NOT very 50% within there own lab. If that was the case then every lab would have to be shut down.

[jwl]

Hopefully I'm not disrespecting GS by posting again, that is certainly not my intent. My intent is clarity about this issue, so I'll post.

Labs do vary highly when testing low frequencies. This is less about the lab itself, and more about the nature of low frequency testing. A good summary is in Ethan's article that was published in Sound and Vibration magazine:

Most US labs are not certified to measure below 100 Hz because they're not large enough to develop the reverberant field on which these tests rely. Rather, at very low frequencies the reverb room's modes dominate, and those modes may or may not align with the standard third octave test frequencies. Further, lab results can vary as much as 50 percent at 125 Hz, even though 125 Hz is within the range of certified frequencies. Results vary even more below 125 Hz, and I've even seen negative sabins reported due to the inherent inaccuracy of the reverberation room method at very low frequencies.

I agree that my saying "up to 50% or more" is probably not the most precise expression of this variance...

But the point is, testing at very low frequencies like this is very difficult to do evenly and precisely, even within the same lab. I do find it ironic that the area where most rooms need the most help is where the most problems exist in terms of testing.

[jwl]

Matt, glad to hear things went well. Fiberglass/rockwool is definitely nasty stuff to work with....

[Ethan Winer]

Just to clarify, labs do vary as much as 50 percent below 100 Hz, but that's from one lab to another. However, if you run the exact same test three times in one lab you'll get slightly different results each time. Especially below 63 Hz. At those low frequencies it's mostly noise. I've even seen negative number reported for absorbers at low frequencies! The random nature of the test procedure helps accuracy at mid and high frequencies, but hurts at low frequencies where the lab room's modes dominate the results.

--Ethan

[Glenn Kuras]

Just to clarify, labs do vary as much as 50 percent below 100 Hz, but that's from one lab to another.

Just to clarify that statement. That 50 percent is between (I believe) 9 labs that that where the top and worst. So not every lab varies between each other 50% and the 2 labs that where WAY OFF THE SCALE I believe are closed or know one uses. The lab we use (Riverbank) fell right in the middle which is why MOST people use them.

Lets just leave it alone before everyone else's eyes GLAZE OVER.

BTW you and JWL remind me of the following.

GET 'EM!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! Tag TEAM!!!!!!!!!!!!!!!!!!!!!!

[Ethan Winer]

Hang on while I find that photo of you and Frank and Bryan Pape all posting at once...

[jwl]

Originally Posted by Glenn Kuras

BTW you and JWL remind me of the following.

GET 'EM!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! Tag TEAM!!!!!!!!!!!!!!!!!!!!!!

Not quite. My beard is bigger, and the tattoo on my left arm is quite different.

[Ethan Winer]

You're also much better looking James!

[yeloocproducer]

related question. Bottom line... what is the best current material for superchunking... 703, Roxul SnS, or Roxul rockboard 60 (which is what, 6lb weight?) I had one insulation place also speak of "safing" insulation made by roxul, 4lb weight, 4" thick, less rigid than most boards.

I would go with SnS or the "safing" if it is better, but I'm concerned it won't be rigid enough to do the wall to ceiling corners... I'm going to do ALOT of this superchunking and I want the material to be cost effective, easy to work with, and of course... best performance below 100hz. Thanks...

[Lemonsqueezer]

Much passion here

Out of interest what program did you use to do your sketch Rednose?

[Glenn Kuras]

Originally Posted by yeloocproducer

related question. Bottom line... what is the best current material for superchunking... 703, Roxul SnS, or Roxul rockboard 60 (which is what, 6lb weight?) I had one insulation place also speak of "safing" insulation made by roxul, 4lb weight, 4" thick, less rigid than most boards.

I would go with SnS or the "safing" if it is better, but I'm concerned it won't be rigid enough to do the wall to ceiling corners... I'm going to do ALOT of this superchunking and I want the material to be cost effective, easy to work with, and of course... best performance below 100hz. Thanks...

In all of my testing I have found that when filling the corner 3 to 4 pound will work best. BUT with that said if you have 6 to 8 pound on hand that will work.

Glenn