Seeking Treatment: Merits of Acoustical Panels, Diffusers, Tube Traps, etc.

[bdiament]

Hi Priaptor,

 

It sounds like your traps were/are placed other than against the room boundaries. Perhaps I'm mistaken.

 

I find trapping all four corners, all four mid-points and all eight quarter points covers the fundamental modes, their first and second harmonics as well as providing reflection absorption and diffusion.

 

I have never found this to be "too much" in any room in which I've created such a setup. In fact, the effects (and benefits) of each trap can be heard individually. Remove the corners and the lowest bottom loses definition. Remove the half-points and the mid-bass bloats. Remove the quarter-points and the upper bass gets "loose".

 

But that's just my experience. It is always interesting to hear about the experiences of other enthusiasts.

 

Best regards,

Barry

www.soundkeeperrecordings.com

www.barrydiamentaudio.com

 

 

[mitchco]

I appreciate your perspective Barry. Your analogy about the broken arm, pretty funny ;-)

 

Times are a changin as the song goes. As an old studio engineer, I would have never believed you could bundle up a multi million dollar recording facility in a $500 software package. But here we are, including on a forum about computer audiophiles in the digital domain - who knew.

 

With the DRC I am using I have not heard any artifacts in the signal path, including listening to my own mixes that came from multi million dollar recording studios. In fact, it sounds exactly as I mixed it.

 

Frequency correction will get you proper timbre as I have outlined in the blog post I referenced. In fact it is so good that it meets or exceeds the speaker manufactures stated frequency response and tolerance as measured in an anechoic chamber. DRC does work and the frequency response graphs prove it. Do you have any frequency response graphs of your nice control room that you could share?

 

Modern day DRC's do work in the time domain - case in point: http://www.juicehifi.com/index.html Have your tried this? Btw, the picture on the TEF computer above also shows time domain as well and that was circa the early 90's.

 

To say DRC is does not work or will never work is simply not true. It's all around us in the cars we drive and the surround sound systems that people buy and most people don't even know it. The state of the art, as with all tech these days, is rapidly increasing.

 

I would say that there are merits to everything audio and worth exploring and experimenting with each one to see if there is merit in it for you. The one thing I learned about audio is that nothing is black or white, just shades of analog :-)

 

Happy Listening!

 

Mitch

 

 

[Priaptor]

First, I did not have all the trial traps long enough to experiment and the "deadening" I am sure had to do with the placement and lack of appropriate time to find best placement for all and a relative difference.

 

My issue with my room is that it is very large and I have literally had to, through the use of traps, mitigate its size to one that is manageable. The before and after difference is incredible.

 

While my corners and front traps are indeed against walls, I have no choice but to use my side traps at the reflection point, somewhat away from the side wall in order to make the listening environment more intimate. It is what I am left to work with.

 

Without ASC, taken this huge "game room" and turning it into a state of the art sound room would not have been possible. I will be getting some more traps for the sides as experimenting with the loaners shows that improvement is possible.

 

I also know that I need to move my speakers slightly further into the room. Given how heavy they are, that is no easy feat. BUT, I am about 90% to where I know I should be.

 

As always I appreciate insight from the pros like yourself.

 

[bdiament]

Hi Mitch,

 

I have taken responses of my room - long ago, when I set it up. Response was within 1.5 dB all the way down, with no EQ or other electronic manipulation.

That said, ultimately, I find such measurements good for diagnosing some issues but not very useful in demonstrating how a room (or device) actually sounds. I've heard plenty of "flat" rooms that are less revealing than the system in my car (which, like all car systems I've heard, stinks ;-}).

 

As I mentioned in an earlier post, the DRCs that work in the time-domain are working on the attack but not on the decay, where the issues lie. Hence, from my perspective, based on having heard several different approaches along these lines, having such a system that truly works awaits a time when DSP can shorten the decay in the room. I don't see that happening any time soon, if ever. But who knows? Perhaps I'll be surprised one day (actually, shocked would be a better descriptive term, should such a day arrive). For now, I wouldn't touch the stuff and would remove it from any system I'm brought in to consult on because I feel it not only doesn't help, it hurts.

 

I understand and respect the fact that you feel differently, as do a number of folks I know. This is one reason why I say if one asks three audio folks a question, they'll get at least four different answers (five of which may be wrong ;-}).

 

What I do know if that we all hear differently and have different priorities in our listening. As I often say in my posts, most things in audio depend very much on what the listener seeks.

 

Best regards,

Barry

www.soundkeeperrecordings.com

www.barrydiamentaudio.com

 

 

[mitchco]

Hey Barry, given that digital signal processing is in everything audio these days, especially computer audio, I am a bit suprised at your response.

 

Response within 1.5db across the frequency range in the listening position without any eq? Sure would love to see the graph...

 

Just for fun, have a closer look at Audiolense and how its time domain correction works. I think your in for your shock :-)

 

All the best,

 

Mitch

 

[bdiament]

Hi Mitch,

 

Yes, within 1.5 all the way down with no EQ or other electronic manipulation. Just a fully treated room and properly placed speakers and subs. But as I said earlier, in my view, a graph is meaningless since it isn't hard to EQ response to flat and still have quite bad sound. (Flat doesn't matter if some frequencies linger in the room after they've stopped in the source.)

 

 

I've looked at Audiolense and see nothing regarding working on decay time. So, sorry, but no shock, no surprise. I'd get interested if they showed time responses instead of frequency response comparisons.

 

I'd also get interested if I'd ever heard one such system in the past that I didn't feel degraded the sound.

 

Again, just my perspective. I respect that you feel otherwise.

 

Best regards,

Barry

www.soundkeeperrecordings.com

www.barrydiamentaudio.com

 

 

 

[DiminishingReturnsOfficer]

It appears that the ASC Tube Traps are regarded as the best method for bass resonance treatment. I went ahead and read Jon Gale's "ABC's of ASC's Tube Traps". He makes some very good points. His premise seems to be that Tube Traps are not bass absorbers, but Resonance absorbers. They will not rob your system of low end dynamics. One of the biggest problems with room modes is that the "original note is heard to decay not at it's true frequency, but at the resonant frequency of the room". This is something that I notice in my room, contributing to the "one note bass" that I'm trying to get rid of. Apparently, the Tube Traps are inherently more effective at dealing with low frequency resonance than pannels. Gale feels that there's no substitute for Tube Traps in the room's corners, but that other devices can be used to treat sidewall reflections. Of course, these guys are pretty darned expensive too. I could go a long ways towards treating my whole room with GIK panels for the price of just one ASC Tube Trap. On their website they claim, for their Monster Trap, an absorbtion coefficient of 3.0 at 80 Hz. "There is no other product on the market that even comes to those numbers". I wonder if these panels operate differently than the Tubes. Are the Tube Traps somehow able to treat only the reverberance or resonance while leaving impact and attack?

 

 

 

[bdiament]

Hi DRO,

 

While panels can be used to absorb early reflections (as can $5 bath towels with pretty much equal effectiveness), in my experience they are simply not as effective as cylindrical type traps (which are based on Harry Olsen's pioneering work from half a century ago).

 

Despite the graphs and the numbers, in my experience, a panel would have to be triple or quadruple the thickness of most commonly available ones (and be hung well off the room boundary to improve its efficiency further) before it gets competitive with the audible results of a well designed cylindrical trap.

 

Further, panels won't do anything for late reflections, which should be diffused.

The nice thing about well designed cylindrical devices (whether ASC's or DIY variations like those from Jon Gale) is that they address bass modes (for real), they address early reflections and they provide diffusion for later reflections, all in a single device.

 

A room full of DIY versions can be built for the price of a single commercial trap and they will actually work. It isn't subtle; with the right amount of traps. properly placed, the differences are immediate and obvious.

 

There are many articles by Art Noxon on ASC's site. I would recommend those as a good place to get more information.

 

Best regards,

Barry

www.soundkeeperrecordings.com

www.barrydiamentaudio.com

 

 

[DiminishingReturnsOfficer]

I will be starting back to work on Monday after a year and a half being laid off. One thing that I missed almost as much as the paychecks was the opportunity to scrounge through the scrap materials left behind by various trades. I understand that the fiberglass pipe insulation used to cover large process and HVAC pipes is good for making tube (type) traps. I'll be on the lookout for some. I've seen the pre formed circular lenghts as big as 30" in diameter. I'm sure something that big would be effective for even the lowest bass. In my case, there's very little output beyond 35 Hz. I looked, just briefly, through a DIY tube trap instructional. It doesn't seem like it would be too difficult and you have the ability to really dress up the finished product. ASC's products are just way too expensive, but I'm sure they're excellent.

 

 

 

[bdiament]

Hi DRO,

 

Unless your room is unusually large, there is no need for a 30" diameter trap.

In my experience, 16" works fine (in corners and midpoints) in a good range of rooms. (9" works great at the quarter points.)

 

Best regards,

Barry

www.soundkeeperrecordings.com

www.barrydiamentaudio.com

 

 

[EvelynArado]

Thanks... Very good points about a router. I didn't think in those terms - but should have (in hindsight!!). The hole saw bit on a drill is definitely a much rougher cut and your advice is right!

 

The stain is a red mahogany color made by Cabots. I didn't add any coating on top of it.

 

Just as a side note - I think that slat diffuser works. I tinkered with it some last night and the dialog from my center channel was noticeably tighter!

 

 

 

 

[DM]

in your room, some corner bass trap will help, big ones, at least 40cm in diameter (2m tall), anything smaller isn't going to help. At least one corner each at the front wall.

 

Also most (90%) of home is too lively for hifi listening (just clap your hands and see if you hear chattering echo) , so you will need adsorption.

 

In your case, most important is the wall behind you, as it is very close, this reflection (very strong) will overlap with the direct sound and kill the sound. Treat your back wall first, then some bass traps. Finally you can add something on the floor (thick carpet) and on the ceiling (if your wife agrees).

 

The side wall reflections are no so bad in your case as you have ~8feet from the side walls and I am sure you toe-in the speakers too.

 

[NickG]

I would highly recommend that you read Floyd Toole's book, 'Sound Reproduction.' Although if the speakers have to placed so close to the front wall, it may be better to use PEQ to rid your room of the low end mode. You can read about room measurement, and download software and the Home Theater Shack website. There is also good instruction on how to build tube traps on the Teres Audio site.