Odd suggestion for Superchunk Traps

[ejmaroney]

Greetings,

I recently put in some superchunk traps in my basement studio.

I'm very pleased with the results, but a friend is giving me grief.

He's a professional musician, and I defer to him on all things guitar, but I honestly don't think he knows a thing about acoustics. Maybe I'm wrong.

Here's what he's suggesting.

He says I need to put a thin strip of wood down the center of of the trap, from floor to ceiling, so that "the sound wave will be split before entering the mineral wood."

I'm at the point where I might just do it to get him off my back, but is there actually something to this?

Thanks,

Eric

[SAC]

You are not wrong...

[Glenn Kuras]

He says I need to put a thin strip of wood down the center of of the trap, from floor to ceiling, so that "the sound wave will be split before entering the mineral wood."

Your friend might be great at somethings but acoustics, sorry to say, he is WAY off base. You can not "cut" a bass wave with a thin strip of wood and even if you could it would have zero benefit. Ask your friend what physics he is using for this method.

Sorry but I have to give your friend a

lol... All in good fun though.

[ejmaroney]

I'll probably just keep quiet and let it go.

And let him keep pickin' for me.

Thanks for the responses.

[Glenn Kuras]

Originally Posted by ejmaroney

I'll probably just keep quiet and let it go.

And let him keep pickin' for me.

Thanks for the responses.

Your a smart man. A week does not go by that when someone in "real life" finds out what I do for a living they have all they "ideas" on how sound/acoustics really work. It truly can be funny at times. Like you though I just smile and say "thank you".

[DanDan]

Tell him you will install the wood strip if he will move all the frets on his guitar to the correct locations.....
I'm being facetious of course. But there is a tiny element of truth behind both suggestions.
You could face your superchunks with quite a few strips of light wood. I guess random sizes and gaps between them. This would bounce a little HF life back into the room. If the gaps are big enough, there should be no loss of LF absorption, you might even gain a little in the low mid. It can be a very good looking practical front for a StudioTips SuperChunk. Take a look over at John Sayers Productions
Be aware that some of his wooden slat fronted devices are somewhat tuned by regular sizes and gaps.
Random would avoid that.
DD

[Ariajazz]

As far as I know bass waves SURROUND objects, they don't stop when they rach and object, I don't thing those big waves will divide or be cut by a thin piece of wood

[Glenn Kuras]

Originally Posted by Ariajazz

As far as I know bass waves SURROUND objects, they don't stop when they rach and object, I don't thing those big waves will divide or be cut by a thin piece of wood

Not at all but I guess you could scatter high end. I have never really liked diffusion in a corner but hey you could always try it.

[Bubbagump]

Noooo! All the waves will divide by two! So if you think it is hard to control 80 Hz, imagine how tough (2) 40 Hz waves will be.

[Pelonis]

A "thin strip of wood" depending on what that really means could have some affect. If he means thin as in the the width(the percentage of how much of the trap is covered), and is talking a fraction of and inch or so, it will have little to no affect. If he means thin as in the thickness or depth and is suggesting to cover a significant area on the face of the trap, this will have significant affect. In this case the wood will have a resonant characteristic and use up some LF energy. The frequency will be specific but with a somewhat wide bandwidth as a result of the broadband absorption quality of the fiberglass. If you were to put several strips of narrow and thin wood in a variety of spacing or a specific, repeatable spacing, you would gain the combination of limp mass and hemholtz and gain some real benefit. The formulas for both are out there if you search.

[Glenn Kuras]

I think it might be wise to read the following to truly understand how diffusion works.
How Diffusion Really Works. Spotlight on MASSIVE Mastering.
Diffusion is a Wonderful Tool by Jeff Hedback

[gremmy]

Originally Posted by Glenn Kuras

Not at all but I guess you could scatter high end. I have never really liked diffusion in a corner but hey you could always try it.

I turned the upper half of my floor-to-ceiling rear superchunks into a 1d binary amplitude phase grating by using an MLS sequence of reflective/absorptive patches. Reflective patches are made from quarter inch plywood. Results are quite nice.

[Pelonis]

Gremmy,

This is a good technique. What you are doing is using impedance for diffusion and also providing a more efficient LF absorber. Impedance vs phase grating is a good system for corners. What you now have is hemholtz, membrane and impedance diffusion all working. I've done this many times with fantastic results.

[PaulP]

Originally Posted by Pelonis

What you are doing is using impedance for diffusion and also providing a more efficient LF absorber. Impedance vs phase grating is a good system for corners. What you now have is hemholtz, membrane and impedance diffusion all working. I've done this many times with fantastic results.

Isn't a sealed enclosure necessary for a helmholtz resonator to function ?
And for a membrane absorber as well I believe.

Paul P

[Pelonis]

Good one Paul. Actually a hemholtz is the opposite of sealed. Consider it a ported enclosure. As far as membrane, any mass will move and use up energy when excited even if hanging in free air. When using a membrane over or within a sealed enclosure, it may become more efficient and also the Tuning and/or Q can adjust. Quite an old tecnique is hanging large pieces of plywood on a rope where LF pressure is occuring. The vibration uses some of the energy and contributes to LF control.

The idea of wood slats over a corner trap would typically consider the area of the trap a ported enclosure. The activity would potentially be hemholtz and membrane. Of course certain conditions may qualify or disqualify either.

[Jeffrey Hedback]

First to Pelonis, great to see you posting here at GS...a true pleasure!

PaulP,

If you are targeting a specific LF issue, then sealed enclosures are a must both in terms of trying to pinpoint the center frequency and adjust the Q for optimal results.

However, Helmholtz and membrane benefits are possible in broader strokes as well. I have done several applications in large rooms that have block walls and dry ceilings (K-13 or similar) using specifically perforated hardboard panels that are glued to 705 and then wrapped in fabric (half the panels with center freq of 250Hz and half at 500Hz). This is not just a large room technique, but as you apply this thought to a smaller room it is an "icing on the cake" application and the rest of the acoustical needs should be well controlled.

[Pelonis]

Hi Jeff,

Been a while. Hope all's well there. I'm thinking of creating a thread and starting it with a bunch of info on LF. I touched a few things here but there is so much more. I think if folks get their head around all that could influence the response, they might not run in circles trying to get a good reference. I have some good test data showing how decay time directly effects the LF response. Some before and after(treatment) decay analysis. Lab results of a few devises used for addressing LF decay. ETC.... Do you think this would be useful for the folks?

[DanDan]

Pelonis, definitely interesting and useful. There is always an bubbling undercurrent of curiousity about sealed panel traps. The idea of relating decay to frequency response intrigues me. Perhaps though, these might be separate threads.
DD

[Jeffrey Hedback]

Hey Chris,

Good to "hear" from you and things are going well (thanks for asking).

I think that thread would be great. People would bring up some very interesting questions. There's a core group that are always searching for more evolved systems.

Two concerns I sometimes have offering suggestions to a specific room are (1) not knowing all relevant information and (2) someone else taking a suggestion as "one-size-fits all". Starting a thread as you're suggesting would avoid those two minor (maybe my own personal) concerns.

Look forward to it.

[Weasel9992]

Hey Chris...I've done work at VMG. Really nice room!

Frank

[ejmaroney]

You guys are way, way beyond where he and I are at...

All he was saying was run a 1/2 cm strip down the center, from floor to ceiling.

Happy to see that it generated a useful discussion though.

[gremmy]

Originally Posted by ejmaroney

You guys are way, way beyond where he and I are at...

All he was saying was run a 1/2 cm strip down the center, from floor to ceiling.

Happy to see that it generated a useful discussion though.

Yeah, the "strip down the middle" thing isn't going to do much of anything useful.

[johndykstra]

Originally Posted by gremmy

Yeah, the "strip down the middle" thing isn't going to do much of anything useful.

I would remove the "much of" from the above statement.

[gremmy]

Originally Posted by dykstraster@gmai

I would remove the "much of" from the above statement.

Agreed.

P.S.

Unless we want to be pedantic about qualifying the extremely limited effect of this magic strip of wood, we could remove the word "useful" as well.

[drummerboy1533]

Ummmm,The flat notes veer left and the sharp notes to the right?