lots of bass traps=dulling of the highs...partially reflective traps?

[Terry McInturff]

My room meaures 11' 5" wide x 24' long x 8' high

Ive straddled the corners with 4" mineral wool floor to cieling

I have a 6' x 4' panel on my back wall (4" min wool)

I have 4' x 4' panels at the reflection points (6" pink)

I have a 4' x 4' panel on the front wall (4" min wool)

I have a 2' x 4' panel on each sidewall behind the speakers (2" min wool)

I have 2" pyramid foam squares scattered around on the front wall cieling

So.........

Im already sensing a "stuffiness"...the high end is going away..and I still have a big null at mix at around 100Hz or so.

If I continue to add more 4" min wool panels, it may get pretty dull sounding. Is it possible to make some of the panels a bit reflective...and where should those semi-reflective panels be?

TONS OF THANKS for all learned input!

[Glenn Kuras]

sure put FRK on the fronts. It will also help absorb more bass.

[Crash]

Originally Posted by Terry McInturff

...and where should those semi-reflective panels be?

I have FRK on all of my traps except those in the RFZ (Reflection Free Zone). Seems to work very well for me. The room is rather tight sounding without being overly dead.

[toolate4roses]

is there a DIY alternative to the FRK?
i live in canada and our insulation dosent come standard with that on it and i fear it could be a pricy special order.

[Strand-old-man]

Pretty sure you´ll find some from some retailer, cause here they even stock foil-covered wool. It´s quite basic stuff anyway. Never bought it though, so I have no idea what the price could be.

However, you can use thicker fabric around your traps. Using too thin will absorb more highs. You can also add sort of thick brown paper (not quite cardboard but almost) under the fabric, that should do the trick.

[Glenn Kuras]

Originally Posted by Strand-old-man

Pretty sure you´ll find some from some retailer, cause here they even stock foil-covered wool. It´s quite basic stuff anyway. Never bought it though, so I have no idea what the price could be.

However, you can use thicker fabric around your traps. Using too thin will absorb more highs. You can also add sort of thick brown paper (not quite cardboard but almost) under the fabric, that should do the trick.

[toolate4roses]

Awsome!
Thanks guys

[Nrt]

My very secret technic in this situation is : Cover them with kitchen paper using staple gun to make the surface more refractive. It wouldn't affect the low frequency.

[Lonely Raven]

Originally Posted by Nrt

My very secret technic in this situation is : Cover them with kitchen paper using staple gun to make the surface more refractive. It wouldn't affect the low frequency.

Define : Kitchen Paper

[Sugarnutz]

Originally Posted by Lonely Raven

Define : Kitchen Paper

Probably talking about Kraft paper or wax paper.

[Nrt]

Originally Posted by Lonely Raven

Define : Kitchen Paper

Bounty = Paper Towel

It works very well. Try it and measure with the acoustic analyzer yourself.

Goreat thing about this is :

1. Paper Towel is organic and porous, so it has neutral acoustic signature. (The surface will look like Minitraps.)
2. It doesn't make any sound by itself.
3. Super easy to handle and dirt cheap.
4. If one layer is not enough, 2 or 3 layers of papers makes less high frequency absorption. Try and measure.
5. Works very well with Owen Cornings.

[toolate4roses]

Say whaaaaaaat?

Anyone else tried this with good results?

[Gharper23]

The frk will really make a difference. I have it on all of my corner traps. And without on the rest of them.

[Nordenstam]

Originally Posted by Nrt

Goreat thing about this is :

1. Paper Towel is organic and porous, so it has neutral acoustic signature. (The surface will look like Minitraps.)
2. It doesn't make any sound by itself.
3. Super easy to handle and dirt cheap.
4. If one layer is not enough, 2 or 3 layers of papers makes less high frequency absorption. Try and measure.
5. Works very well with Owen Cornings.

Be afraid. Very afraid. There are people out there with lighters! Muahahaha...

Sounds F'ing dangerous to me.

[R_O]

Building devices to absorb low frequencies means you've gotta add a "low-pass" filter. Just as you would using EQ.

A "filter" might be anything from kitchen-towels to a piece of hardboard. It depends on how low you want to filter. I usually add a plastic screen, it'll reflect mid/high but will absorb low/midlow. If tests read out I've still got too much low vs high (read: too much high absorption), I'll add another or thicker screen. Or I make it a slatted device.

My advise is to add a plastic sheet. You are planning on using wall (broadband) absorbers, aren't you?

And.. Lupo's got a point; don't forget to build is fire-proof (if possible)!

[toolate4roses]

Was that question directed at me?
If so, I am making Masonite bass traps/diffusers built around the corners. I figured for maximum effectiveness I should cover the insulation I am using with FRK (or DIY equivilant) before installing the Masonite over it. It is a fairly small room
so I figured I'd need all the help I can get with the lows.

[Yiannis]

does the frk,plastic or whatever.... has to be glued on the rock wool or its ok if I put it behind the cover with some pushpins?

[Magickman]

Originally Posted by Yiannis

does the frk,plastic or whatever.... has to be glued on the rock wool or its ok if I put it behind the cover with some pushpins?

It doesn't have to be attached to wool, although from what I've seen, it seems you get a little bit of extra low freq. absorption if the scrim is in contact (i.e. - touching, but not necessarily attached to) with the wool.

Good ranges of plastic thickness are are 1 mil to 6 mil. Keep in mind that beyond a certain thickness you will lower the low freq. absorption and widen the Q.

FWIW.

-MM

[Yiannis]

thank you

[Yiannis]

Maby its a stupid question but is this gonna work?

Bubble Wrap - Wikipedia, the free encyclopedia

[RKrizman]

Originally Posted by Yiannis

Maby its a stupid question but is this gonna work?

Bubble Wrap - Wikipedia, the free encyclopedia

Great, now you can get diffusion at the same time !

-R

[Yiannis]

Originally Posted by RKrizman

Great, now you can get diffusion at the same time !

-R

are you serious or just kidding?

[Ry Thomas]

Originally Posted by Glenn Kuras

sure put FRK on the fronts. It will also help absorb more bass.

Glenn, can you tell us which traps and which points of the room the FRK should be placed?

My new studio build will be started soon

[RKrizman]

Originally Posted by Yiannis

are you serious or just kidding?

I'm really not sure !

-R

[Mark Dubosky]

Bass traps will not affect the high frequencies as long as the traps have even absorption across the entire audio spectrum.

Looking at what you have done, it seems that your problem is more likely related to using the mineral wool in the corners and the 2" panels and wedges.

For proper tonal balance, the room should be largly reflective at all frequencies, along with broad-band absorption on the wall behing the speakers, unless they are soffit mounted. Additionally, the foam wedges should not be less than 4" thick.

It may seem counterintuitive, but thicker wedges will actually allow you to hear MORE high frequency information than thinner foam, carpet, or wool. This is because the cutoff frequency between absorption and reflection is lower, thereby not simply absorbing the highs and leaving the bass and midrange reflective, which leads to "dulling".

In my room, I covered my entire back wall behind the speakers with 12" Auralex Venus Bass traps, which are simply very broad-band abosrbers, used 4' x 4" wedges directly behind the listening position on the back wall, and 4' x 4" wedges on the side wall to eliminate local specular side reflections.

All other surfaces are hard plaster walls and oak hardwood flooring.

The result is a room that is essentially flat from around 100-150 hz to over 10khz, +- 3db at the listening position and areas immediately around it.

In summary, the trick is to absorb ALL frequencies where needed, and leave the rest reflective at ALL frequencies. What you do not want is narrowband absorption, resulting in a skewed tonal balance and smearing or masking of recorded spatial information.

[Yiannis]

Finally I bought plastic 210 gr /m2.

My front wall has 15 cm rockwooll and my speakers are almost touching the wall.

I am sitting about 1,2 m from the wall so should I put the plastic there or not?

[PaulP]

Originally Posted by Yiannis
are you serious or just kidding?

Originally Posted by RKrizman

I'm really not sure !

An interesting idea. And there are small bubbles and large bubbles.

Easy enough to test though, just stick one to an absorber and see what
happens.

One more crazy idea to hang on to.

Paul P

[SAC]

I hope the suggestion was meant facetiously... ;-)

Forget bubble wrap as anything other than a plastic layer.

Aside from the fact that 1" bubble wrap is essentially a flat bubble, you really don't care about selectively addressing frequencies above 13.5 kHz.

There are enough valid ideas that too many ignore without inventing other half-baked ideas to chase.

[Nrt]

Originally Posted by Lupo

Be afraid. Very afraid. There are people out there with lighters! Muahahaha...

Sounds F'ing dangerous to me.

Actually, Bubble wrap is more dangerous than paper towel in a fire, since bubble wrap makes chemical gas. I used organic material as much as possible in my room. It makes me feel more relax because of their neutral sound reflection, even if it's not perfectly fire proofed. Paper towel on the wall is NOT against the building code, it is considered as a curtain, if its not covered by the cloth. If it's covered by the acoustic cloth / panel like my studio, it is basically considered as a regular form with paper attached.

Peper towel method is very simple, so it may sound like a joke, but I tested / measured in my room and the result is very favorable in terms of both number and feeling. Probably, I should have patented it.

[SAC]

Bounty or Brawny? And is there a difference in performance depending upon which printed pattern it has? Sorry, ...couldn't resist...

1 or 2 mil plastic sheeting (or even aluminum foil) is easily sourced and handled, inexpensive, and much more resilient in assemblage without tearing and easily accepts spray surface adhesive that makes it easier to apply and remain in place as it is covered and hung.

...And ironically, for a given quantity, cheaper than paper towels!

And while I must admit to never having bothered to compare the two, my money would be on the plastic for being a marginally better reflector that the fibrous paper...

Debating which substitute material might work really isn't that worthwhile with such readily available proven methods so easily sourced. But if you are going to try something different, I would confirm the absorbers behavior with measurements.

But this really isn't that complicated folks...