Bass Traps in All Corners

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Hipper

Bass Traps in All Corners
« on: 18 Mar 2017, 11:44 am »
I want to discuss generally the use of Soffit Bass Traps in a smallish room (my room is [l x w x h] 14' x 13' x 8' [420cm x 386cm x 240cm]).

In theory anyway, if it's practical, should Soffit Traps be employed in all corners, namely floor-wall, ceiling wall, wall-wall. In other words for a room with my dimensions it would employ about 26 Soffit Traps (I currently have 13).

Can you ever have too many? Would this be overdamping?

Even with 13 traps (plus a six 242/244 panels) and careful placement of speakers etc. the bass is not very flat and there are suckouts. I resort to using a digital equaliser to help deal with this.

Generally I would like to reproduce a sound that is a headphone type experience - relatively dry but extremely accurate - that is my taste.

Like I say, I would prefer a general discussion as I can contact GIK direct to discuss my specific requirements. I just mentioned my situation to give an idea of where I'm coming from.


Glenn Kuras

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Re: Bass Traps in All Corners
« Reply #1 on: 18 Mar 2017, 01:10 pm »
The term "suck out" is a bit of a myth. There is no way to subtract from the sound that is coming out of the speakers. Generally speaking the "room" causes nulls, peaks with decay (reverb) so treating the room brings you closer to what is actually coming out of the speakers. Now with that said the human ear may prefer some of a room sound, which is why we try to treat a room that does not take away ALL room "sound". The trick though is to do it in a way that does it correctly across the spectrum.   
1)Absorb as much of the low end so the bass is smooth/punchy.
2)Semi absorb mids for the same reason.
3)Upper frequencies absorption, but retain as much of it (later reflections) to give a "sense" of the room without it being the main focus. This is where we can start to use diffusion to help delay/change the upper reflections arriving at your ears.

Now to get to your room, you really cannot over absorb "bass" (suck out) so sure adding to every corner will only tighten up the low end. Basically letting you hear what is coming out of the speakers without decay with nulls/peaks. With that said though the soffit is a full range bass trap, so it will also absorb the mids and upper frequencies which you may or may not want. In a case like yours I would custom build them with our limiters in them so it will reflect upper energy back into the room. FYI this is a big reason we introduced our Alpha and Impression products. ;)
http://www.gikacoustics.com/product-category/alpha-series/

Glenn Kuras
GIK Acoustics

Hipper

Re: Bass Traps in All Corners
« Reply #2 on: 20 Mar 2017, 06:21 pm »
Thanks Glenn.

Sorry for the use of the phrase 'suck out'. I appreciate 'null' is more accurate.

My speakers have ribbon mid and high drivers and their dispersion both horizontally and vertically, along with their placement, means I don't think I get too much in the way of reflections. If that is true then the impact of broadband absorption in the corners of the room would be limited, wouldn't it? Mostly reflections seems to be considered for flat areas - walls, ceilings.

I do have 242/244s on the front and rear walls but not on the side walls.

Are you saying that Soffit Bass Traps can have limiters installed? Presumably that makes them heavier?

Of course using reflections is where theory and taste comes into it. I assume that a recording will contain the ambience of it's venue so adding your listening room ambience would damage that. Having said that it seems, according to Floyd Toole's research, that side wall reflections are preferred.


Glenn Kuras

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Re: Bass Traps in All Corners
« Reply #3 on: 20 Mar 2017, 06:45 pm »
I don't totally agree with Floyd but I don't totally disagree with him either. :scratch: :lol: Depending on the room size, having a BIT of early reflections on the side walls can make things sound "wider" but the it does hurt the imaging. If your room was a mixing room I would talk you out of diffusion on the side walls as you have to hear the slightest amount of panning. If you use diffusion (smaller room) you would miss some of that. As a listening room though it really is personal preference.  Just know that getting any reflection from the side walls is going to "color" the recording. Maybe a good thing, but maybe not. Once again personal preference. ;) Personally I like a little diffusion when just listening, but when mixing it is a NO GO!!  :thumb:

Yes it will make the Soffit a bit more heavy.

Ribbon or not you still get reflections so not sure what you mean by that. 

Hipper

Re: Bass Traps in All Corners
« Reply #4 on: 20 Mar 2017, 07:24 pm »
The ribbon panels are said to have 30 degrees dispersion. I would guess that means for the main body of sound energy from the speakers but that weaker signals still go wider.

My question was really how much mid and high frequency energy go into the room corners (and so are absorbed by Soffit Traps).

Glenn Kuras

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Re: Bass Traps in All Corners
« Reply #5 on: 21 Mar 2017, 12:14 pm »
Corners for the most part are not going to be a problem as far as early reflections on the upper frequencies, BUT you can still get a lot of "PINGING" and general upper decay.  Not the main place to treat upper frequencies, but you still have to be mindful of them. With that said though using the limiter is a great idea when you already have full range absorption in other corners.

JWL.GIK

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Re: Bass Traps in All Corners
« Reply #6 on: 27 Mar 2017, 03:19 pm »
It's quite true that speakers have different dispersion properties, but all speakers will produce reflections in a room. If you don't believe me, play music on your system, then go stand at one of the reflection points. If you can't hear any audio there, then congratulations, you won't have any reflections.  :thumb:

I agree, you can't have too much bass trapping in a room. Many of my clients over the years were astonished that implementing a good bass trapping strategy made the bass louder in their room. You can, however, have too much high frequency absorption, so using range limiters is smart for sure. You can then, as Glenn says, use other products (Alpha series, etc) to get the right balance for the highs. Details here:
http://www.gikacoustics.com/a-well-balanced-audio-room-using-giks-patented-treatments/

Hipper

Re: Bass Traps in All Corners
« Reply #7 on: 28 Mar 2017, 07:13 am »
Thanks for the link.

The article says that a limiter not only reduces upper and mid range absorption but enhances bass absorption.

For a Soffit Trap, how would that affect the test results shown on your site?

There is an image of a Corner CT Alpha Bass Trap with the limiter on the outside. Is that how a Soffit Trap would look or would the limiter be hidden behind the covering (like the 244s I have with a Scatter Plate)?

JWL.GIK

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Re: Bass Traps in All Corners
« Reply #8 on: 28 Mar 2017, 04:05 pm »
Hi Hipper, I'm not sure that we've had the Soffit Trap with the Range Limiter tested. All our test data is on our site, so those tests may not be available at this time.

But to get an idea of what the Range Limiter does, take a look at this graph of the 244 with and without the range limiter:



The Soffit Trap gives much more absorption under 125Hz than the 244, so the effect of the Range Limiter will be even more pronounced.

Hipper

Re: Bass Traps in All Corners
« Reply #9 on: 29 Mar 2017, 07:46 pm »
Thanks. That's impressive.

I would guess then that even if I don't particularly require reduction in high frequencies in corners I would get additional bass absorption, at least below 125Hz. From only a bass control point of view then I suppose it's a question of cost and flexibility - use the money for standard Soffit Traps in more corners, or less Soffit Traps plus Limiters in less corners.

JWL.GIK

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Re: Bass Traps in All Corners
« Reply #10 on: 7 Apr 2017, 06:19 pm »
The Range Limiters can be added for $30, so it's not *that* much more to add them.

And yes, you can't really have too much bass absorption in a small room, so best case is to get as many SoffitTraps into the room as possible, and put Range Limiters on them all.