Low frequency suck out, what can'I do?

roscoeiii · « **Reply #20 on:** 29 Dec 2010, 06:45 pm »

+/- 2.5 dB is a mighty tight tolerance. Well done if you have achieved that in your room. Looks like even Paul's EQed measurements weren't able to achieve that.

I am curious what other folks who have done a lot of treatment and measurements view as an acceptable range of deviation in their listening rooms...

Levi · « **Reply #21 on:** 29 Dec 2010, 06:57 pm »

Agreed! Equipment calibration and accuracy plays a great importance. My equipment may not be as accurate but once I see an improvement before/after treatment, I am satisfied with my room. Brian's (GIK) expertise helped.

Mike Nomad · « **Reply #22 on:** 29 Dec 2010, 07:08 pm »

Quote from: pelliott321 on 29 Dec 2010, 04:16 pm

...I certainly would not worry unless you are definitely hearing (or not hearing ) a problem...Sit back and just enjoy the great music I am sure your system produces.

A big +1 here. Given the length of your room, chasing something that is only a graph problem below 46 Hz. is a dicey proposition. If I'm looking at your graphs correctly, your LF dip is somewhere a little below that.

Do you have any treatment(s) on the back wall?

pjchappy · « **Reply #23 on:** 29 Dec 2010, 09:30 pm »

Quote from: roscoeiii on 29 Dec 2010, 06:45 pm

Looks like even Paul's EQed measurements weren't able to achieve that.

Yeah, but the sound gets much, much better when I change the graphs from 1/12th octave smoothing (all but the first one posted) to 1/3 octave smoothing.

Paul

roscoeiii · « **Reply #24 on:** 29 Dec 2010, 10:15 pm »

That I don't doubt. My point was the +/- 2.5 dB is a pretty strict tolerance given room effects, one that even EQing would potentially have difficulty achieving.

pjchappy · « **Reply #25 on:** 29 Dec 2010, 10:16 pm »

Oh, I know. I was just being facetious.

Paul

saisunil · « **Reply #26 on:** 29 Dec 2010, 10:26 pm »

Quote from: MaxCast on 29 Dec 2010, 12:26 pm

Did all you treatment items come from your level 1 purchase? I would call Rives and see what they had to say first.

If I were you ...

I would knock on Rives door a few times ...
Work on room placement
Get more traps - bass and high frequency ... since you are in Malaysia - you could try going diy route with your choice of fabric ...

You may want to look into Get Better Sound book

Good Luck ... your room deserves better sound...

roscoeiii · « **Reply #27 on:** 29 Dec 2010, 10:30 pm »

x2 on buying Get Better Sound.

audioblazer · « **Reply #28 on:** 30 Dec 2010, 01:21 pm »

Maxcast,
I have not try to use my HT processor to equalizer whatever room
anomalies I m facing. Not competent to use it and my priority is 2 channel listening

audioblazer · « **Reply #29 on:** 30 Dec 2010, 01:39 pm »

Ethan
will look into more bass panel. Actually there are not many places to put bass trap except beside the front resonator where I can put 1x 4' panel and beside the side wall resonator I can put another 2x4' panel. However I m concern it may absorb too much of the upper freq which is currently not as extended as I want. Anyway will look into your suggestion

audioblazer · « **Reply #30 on:** 30 Dec 2010, 01:46 pm »

Pj
I tried integrating my jl audio F113 sub with my main speaker. Without using an external crossover I find it difficult to integrate the sub to the main speaker. Anyway, equaliser may help to alleviate the peaks but not the null right? Thks for your suggestion

audioblazer · « **Reply #31 on:** 30 Dec 2010, 01:50 pm »

Levi,
I did spent a few days shifting my speaker around and discovered that by moving my listening position about 2ft back I was able to alleviate my bass issue. However it's too near my door and closer to my back wall than I would like to.

Initial listening position , 7 ft from back wall

Subsequent listening position about 5ft from back wall

BobM · « **Reply #32 on:** 30 Dec 2010, 02:01 pm »

Tradeoff's. We all have them.

audioblazer · « **Reply #33 on:** 30 Dec 2010, 03:43 pm »

Mctwins
Those cornertraps don't help you below 100Hz no matter who say's what. Throw them away and buy some real Helmholtz resonators (a box tuned at specific freq). Remove the curved panelresonator as well and add some diffusion panels instead. All around the side wall and front wall and ceiling.

I think there are many ways to skin the cat otherwise a lof of the so called acoustic treatment expert would have to close down their company. anyway is there any linked to the real helmholtz resonator to solved below 100hz bass issue? thks for your feedback

audioblazer · « **Reply #34 on:** 30 Dec 2010, 03:49 pm »

Mike Nomad

A big +1 here. Given the length of your room, chasing something that is only a graph problem below 46 Hz. is a dicey proposition. If I'm looking at your graphs correctly, your LF dip is somewhere a little below that.

Do you have any treatment(s) on the back wall ?
why do u said that a 24.5ft length room cant go below 46hz? Would appreciate if you can elaborate
Back wall is fillted with LP racks and there is 2 2x4 ft absorption panel near each side of the corner trap

Ethan Winer · « **Reply #35 on:** 30 Dec 2010, 04:56 pm »

Quote from: audioblazer on 30 Dec 2010, 01:39 pm

will look into more bass panel ... I m concern it may absorb too much of the upper freq which is currently not as extended as I want.

You can buy (or make) bass traps that absorb mostly bass, and absorb less mids and highs.

--Ethan

audioblazer · « **Reply #36 on:** 30 Dec 2010, 05:14 pm »

Ethan, what are the real trap products that absorb mostly bass? Do they work on low bass? Thanks

bpape · « **Reply #37 on:** 30 Dec 2010, 05:25 pm »

46Hz is still very much in the music range. While a little 'extra' down there is sometimes fun (though not accurate), a loss of that foundation in the deepest bass can make things sound thin and with less impact.

Instruments going down below 46Hz include piano, drum, bassoon, organ, bass (electric and stand up acoustic), tuba, etc.

Considering the fact that this is also doing HT duties, it's even more important. Movie soundtracks can go down as low as 15Hz (some even lower).

Bryan

McTwins · « **Reply #38 on:** 30 Dec 2010, 06:02 pm »

Hi
Audioblazer....

Look here;
http://www.performanceacousticslabs.com/PAL/Home-Acoustics_Listening_Rooms.html

You can find great pictures of some real room acoustics, and it works.

Did you see my previously link. This is my decicated listening room and I did it by myself. I have been on the same path as you with so called basstraps and absorbtion stuff that don't seems to work, acoustically speaking. Remember, I only have diffusion all around, side wall, front and back wall, ceiling and Helmholtz resonators and slat resonators. You can clearly see the before and after measurements, most importanly, the T30, CSD and Energy Decay. If you absorb like you have been doing you are only deadening the room but if you use proper diffusion you will have more ambiance and still have low reverberation time in the room.

Your speakers deserve a better room acoustics then what you have now.

Thanks

Mike Nomad · « **Reply #39 on:** 30 Dec 2010, 08:56 pm »

Quote from: audioblazer on 30 Dec 2010, 03:49 pm

Mike Nomad

A big +1 here. Given the length of your room, chasing something that is only a graph problem below 46 Hz. is a dicey proposition. If I'm looking at your graphs correctly, your LF dip is somewhere a little below that.

Do you have any treatment(s) on the back wall ?
why do u said that a 24.5ft length room cant go below 46hz? Would appreciate if you can elaborate
Back wall is fillted with LP racks and there is 2 2x4 ft absorption panel near each side of the corner trap

The frequency of your room can be determined (in feet): 1126 (speed of sound) / 24.5 (length of room) = 45.959 (as Hz). That represents the longest (lowest) frequency that will directly image in the room.

That does not mean that I am suggesting that everything below 46 Hz is a waste. However, there are a number of issues, including direct vs. reflective sound. Sure, you can hear freqs lower than 46 Hz in the room, but you are getting them reflectively.

Not surprising, your most recent plots suggest that moving your speakers (as some people suggested) had a significant, positive result. The call for more bass traps, etc. is, I think, unwarranted until at a minimum, you have finalized the placement of your speakers. I would continue to work with speaker placement to see (hear) if you can improve things further.

There is a pretty good sized set of variables to contend with, and since I don't know your background, suggesting references for a better understanding of what you have to deal with may be redundant. The two books that I use the most are:

Sound Reinforcement Handbook, 2nd Edition (written for Yamaha by Gary Davis & Ralph Jones) -- Pretty easy to digest. A lot of basic audio theory and loads of practical application. Includes some basic math, and the schematics are pretty easy to follow. It's available through Hal Leonard Publishing, and runs USD $35. I'm assuming it is still in print. A used copy shouldn't be tough to locate.

For more detail, there is Handbook for Sound Engineers (I have a 3rd Ed. I think it's up to a 4th), edited by Glen M. Ballou. A LOT more detail, this has moderate amounts of both schematics and somewhat advanced math. However, there is still much in it useful for people who aren't EEs, etc. It's available through Focal Press, and is a bit more expensive: At 1500+ pages, it will set you back about $100.