Quote:
Originally Posted by
RyanC
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I've also played with some multi-sub setups
It seems to me that the big shortfall is that it's effectiveness is inversely proportional to the effectiveness of the rooms LF treatment. Ultimately in free space, subs that vary in distance (or time of arrival) to the listening position will interfere with each others response.
So the downside is any treatment you do add to the room will actually tend to make the multi-sub less effective.
If you look at Dr Geddes approach, he is adamant that you DON'T have any ER treatment on the sidewalls. Instead the constant directivity speakers are used to eliminate L speaker to Left side reflections- but then the downside is that left speaker to right wall reflection is effectively the ISD termination (which is going to be less than ~20ms in most rooms). There was a thread where he reluctantly admitted to having some sort of cloud/kicker on the ceiling though.
Also Geddes advocates only one full range sub, and then the filler subs to be bandpass enclosures that are custom built to cover the Schroeder range (and not below)- I guess to minimize the need for time correction. If you look at his (*ahem* aggressive) posts over at DIYaudio he certainly does not approve of most multi-sub implementations.
IMO Dr Geddes overall approach is an amazing balance of available compromises- but I'm not sure it takes into account the idea of a bespoke listening room. I heard his setup at RMAF a while back- it was frankly stunning for such a humble setup. Totally the wrong market for his message though...
Thanks for piping in Ryan, it's great to talk with others who have experience with this. My take on Geddes is that he is very advanced in his understanding and implementation, and, pretty unique in that he has a full understanding and real engineering abilities in sound reproduction as a whole system- actually designing speakers around the way they interact with a room. As you say I don't think his work is necessarily aimed at bespoke listening rooms or music production spaces. It seems many people who equip nice home listening rooms actually prefer early reflections whereas audio/music types perceive how they smear things and that too many early reflection makes it hard to listen/mix. Would love to hear a full-on Geddes room!
What I have been interested is how to take the more typical residential rooms we all live in and bring them up to a very useable professional level for music production. I am 53 and started playing/recording guitar in pro studios when I was 16. I have composed, performed played and recorded all these years and worked as an audio engineer in the 80s and 90s. Even most of the big studios were generally disappointing in how they sounded, ie you could not simply listen to what you heard and trust it. Nowadays it seems like most people are working in either residential or light commercial spaces which are even worse then the big studios of yesteryear (mostly because of small room modal type issues).
There are awesome acoustical products these days to help address reflections, diffusion, absorption that are all effective in highs, mids and even low mids. However me and my obsessively nerdy music/audio friends have struggled for years and year to make real progress in our residential rooms with being able to trust the low end. All of us have been told over and over to keep adding more fiberglass products and when that just does not work add more "bass traps" - except these dont really work either, at least the ones that anyone can actually afford enough of and can physically fit in these rooms!
This is where the multi-sub thing caught our attention and being ridiculous obsessive nerds we have gone somewhat bat-sh*t-crazy in testing far too many iterations for sane people!! Trying different speakers, placements, DSP units, ways of tuning them, brands of subwoofers, etc. and yes we have very annoyed spouses and contracts in place to NOT play pink noise or sweeps while they are home!!
But the bottom line is that multiple subs along the lines of the Harmon research allow you to take an otherwise acoustically crappy residential room and be able to really hear and trust the low end. Is it a Northward level room- Of Course Not!! But it is possible to create a trustable reference listening environments by simply adding 4 subs, some smarts around configuring a DSP processor, careful placement, etc. --YES!!!
BTW- here is that same crappy room I posted before using the JBL 308s mains with cheap-a$$ Behringer subs with both the 2 sub and 4 sub config....