Rooms Acoustics... The Final Frontier.

by mugenfoo on Mon Dec 12, 2011 2:53 pm

To borrow a phrase from Star Trek ("Space... the Final Frontier"), many a hi-fi enthusiast have tended to shy away from the topic of room acoustics and how its condition affects the qualities of home audio reproduction.

To start off, it would be good to reference some industry experts in the field.

One person comes to mind: Ethan Winer, long time musician, recording engineer and co-founder of RealTraps Inc, a company that specialises in manufacturing and selling Acoustic Treatment solutions used by renowned record labels & mastering engineers alike.
http://www.realtraps.com/reviews.htm

http://www.ethanwiner.com/acoustics.html

Information overload anyone ... ? More to come...

by mugenfoo on Mon Dec 12, 2011 4:21 pm

Foam Treatment : What works, what doesn't.

http://www.harbeth.co.uk/usergroup/showthread.php?719-How-much-room-damping-needed-for-quiet-listening&p=7638#post7638

Alan Saw at the H.U.G. wrote:
First - and this is really important - a few 50cm x 50 cms pieces of absorber foam sprinkled around the room just will not do anything other than make you poorer. Think about this: to make any worthwhile difference, the absorber must occupy a minimum of about 25% of the entire surface area of the room's four walls + ceiling. Two or three pieces of foam, even pretty sculptured foam, will be completely useless as a general absorber. They just don't cover enough area to make a difference.

Then, separate issue: to absorb low frequencies you need thick, deep absorbers perhaps 1m thick or panel absorbers (see here). Therefore, it is really irrelevant whether the skimpy foam is placed tight into the corner or away - it's going to make no difference what so ever at low frequencies. It may well absorb a little in the middle frequencies and better still in the higher frequencies. But at the bass end - useless.

If all architectural acoustic issues could be solved at a stroke with a skimpy bit of damping here and there, highly paid acoustic consultants would be out of business - project here . Architectural acoustics is big business employing the best brains and the most sophisticated measuring and computer modelling equipment. You won't find any room tuning bells used in acoustic design for obvious professional reasons.

Alan A. Shaw
Designer, owner
Harbeth Audio UK

by **htkaki** on Mon Dec 12, 2011 4:33 pm

Agree. LF is the hardest to treat.

25% of entire room surface. Hmm... I guess mine is probably slightly more than that. 4 corner traps at the top 4 corners, 2 big cyclinder bass traps up front which are often being mistaken as SVS Pc cylinder subs, 2 DIY bass traps by using CSR Bradford 80kg/f rockwool in a 4' H x 2' W x 5" D frame. , 14pcs 2' x 2' skyline diffuser, and more than hald a dozen of acoustic panels. Floor is carpeted as well.

by JediSavant on Mon Dec 12, 2011 5:07 pm

This Hah-beht guy is pretty arrogant and dogmatic... If he so good, then he should do all the other stuff he says people do badly... instead he only make old fashion lah-pah... Where d HaH-Beht amp? Hah-Beht Cable? Hah-bet wall cushion?

I can think of another "Beht" but better not post here in case I get accused of being vulgar in dialect...

by JediSavant on Mon Dec 12, 2011 5:08 pm

For low-end, an empty trunk filled with some cushions is a good bet... natural resonator with no hole, so definitely not Hemholz...

by mugenfoo on Mon Dec 12, 2011 5:41 pm

JediSavant wrote:This Hah-beht guy is pretty arrogant and dogmatic... If he so good, then he should do all the other stuff he says people do badly... instead he only make old fashion lah-pah... Where d HaH-Beht amp? Hah-Beht Cable? Hah-bet wall cushion?

I can think of another "Beht" but better not post here in case I get accused of being vulgar in dialect...

Yes .... dogmatic he may be & rightfully so, but he IS the owner of a very successful Global speaker brand.
The fact that he makes himself accessible to his customers via the H.U.G. , definitely doesn't put him in the arrogant category.

Alan Shaw: Dogmatic, yes.... opinionated? Definitely ... but arrogant, not quite.

This is my personal favourite:
"You won't find any room tuning bells used in acoustic design for obvious professional reasons."
The same could be extended to mini-teacups, rakes, rods, woody-cubes, square bricks (claiming to be some voodoo radiation or EM field device).... Razz

Now back to the point of room acoustics...

by JediSavant on Mon Dec 12, 2011 5:43 pm

Happy Harbeth Day everybody!!

by JediSavant on Mon Dec 12, 2011 5:44 pm

By the way, I know the guys who did all the work in the second link to the Melbourne Recital Centre project...

by mugenfoo on Mon Dec 12, 2011 5:48 pm

htkaki wrote:Agree. LF is the hardest to treat.

25% of entire room surface. Hmm... I guess mine is probably slightly more than that. 4 corner traps at the top 4 corners, 2 big cyclinder bass traps up front which are often being mistaken as SVS Pc cylinder subs, 2 DIY bass traps by using CSR Bradford 80kg/f rockwool in a 4' H x 2' W x 5" D frame. , 14pcs 2' x 2' skyline diffuser, and more than hald a dozen of acoustic panels. Floor is carpeted as well.

Actually, htkaki has the luxury & foresight of a purpose built room.
This in itself already is a very good bonus that most people cannot have unless they build their own rooms to specific dimensions.

Which brings to the topic of the best room dimensions for hifi:

One may refer to Robert Harley's book, the Complete guide to Hi-End Audio. The top choice is 10 x 14 x 19, but with some caveats of course... Wink

the dimensions of 10 14 19 proposes a good spread of room modes such that they are quite well placed away from each other.

The anti-thesis of this would be a "square room", in which its horizontal, vertical and lateral room resonances are all at the same frequencies. Same goes for any room dimension that would be integer multiples of each other. Such rooms would require very heavy acoustic treatment to counteract the effects of reinforced room resonances.

by JediSavant on Mon Dec 12, 2011 5:54 pm

Golden ratio....1.62

by mugenfoo on Mon Dec 12, 2011 6:06 pm

Based on the Linkwitz Lab room mode calculator, a 10 x 14 x 19 room definitely has a favourable distribution of room modes .

But do bear in mind, that any room mode would be detrimental to the sound. But at least one knows which are the problem freqs, and go about addressing them...

by mugenfoo on Mon Dec 12, 2011 6:09 pm

JediSavant wrote:Golden ratio....1.62

OK, lets try it with the Room mode calculator ... see what results it gives...
10 x 16.2 x 26.24:

Nope .... not really good distribution of room modes! (look at the black traces).

This room would have serious boom issues around 70Hz, 95Hz & 115Hz .

by JediSavant on Mon Dec 12, 2011 6:16 pm

aiyo... 14x19 is short of the golden ratio la...
this one ends up being 1.35...

so if 1.62, it could be say 14x22.68... can round up or down? which do you prefer?

Rooms Acoustics... The Final Frontier.

Rooms Acoustics... The Final Frontier.

Re: Rooms Acoustics... The Final Frontier.

Re: Rooms Acoustics... The Final Frontier.

Re: Rooms Acoustics... The Final Frontier.

Re: Rooms Acoustics... The Final Frontier.

Re: Rooms Acoustics... The Final Frontier.

Re: Rooms Acoustics... The Final Frontier.

Re: Rooms Acoustics... The Final Frontier.

Re: Rooms Acoustics... The Final Frontier.

Re: Rooms Acoustics... The Final Frontier.

Re: Rooms Acoustics... The Final Frontier.

Re: Rooms Acoustics... The Final Frontier.

Re: Rooms Acoustics... The Final Frontier.