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Sub placement

Greetings all and thanks in advance regarding this question.

Go to the “about” page to see my equipment and room:
theaudioatticvinylsundays.com

I have had the same equipment more or less for 30+ years, excepting the sub, which was added 7 years ago. The only other major change has been the room. Three years ago, I moved from a lively, noisy lower Manhattan loft of 41 years to a room that has walls and ceiling insulated with 6” to 17” of rockwool covered by burlap, snd 7” of rockwool under the floorboards between the joists. This made a decided improvement.

In spite of all the insulation, the room, with its weird shape - two dormers and a gable - does present some challenges.

I have never been happy with the sub placement.

I had been following the advice of a friend who worked as the sound engineer at the UN. He said to put it where you sit, walk around the room until you find the spot where it sounds best, and then put it there.

There was never a spot where it sounded best. A few that sounded better, but did not stand out in any way. I would try one for a few months, then tire of it and try another.

Over the weekend, I spent a few hours cleaning out the dust in the amps, resetting the tubes, rotating the Altec drivers in the cabinets, etc.

For some reason, I thought that, hey, I never tried putting the sub behind the listening spot. So I put it under my desk, which is about 3 feet directly behind the armchair where I sit to listen.

Voila.

Anyone have any experience with the sub behind the listening spot? Is this weird or actually not so uncommon?

Anyone venture a guess as to why that would work? A recording studio friend who I thought would make more than an educated guess said to just file it under “hey, it works, don’t think too hard about it, just sit back and enjoy!”

I suppose “home theatre systems” with their half dozen or more speakers around the room do this all the time, but I’m not getting why putting everything from 20 to 70 behind me and everything from 70 to 20,000 in front of me would not only help make the bass more textured and authoritative, but also help open up the rest of the soundstage: make it feel airier, clearer and more detailed.

The downside is that I now feel like I’m sitting on the stage instead of in front of it. I’m finding that dialing the phono-stage back and forth helps with that, as does dialing around the BME Sonic maximizer (don’t laugh: they are analog, and they work), so I think that will eventually resolve itself.
128x128unreceivedogma
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oldhvymec
5,101 posts
 
I suspect you’re getting the bass delivered at two or three different times.

The floor still transfers the bass waves which are quite long, FASTER than the drivers do through the air. Wood or Stone are quit good sound transfer materials. Wood even more so for bass.

Your getting the bass from the mains, and the subs coupled to the floor. Then the bass from the actual drivers and reflection point via air.

You DECOUPLE the speakers, things will really start to make sense..
In stead of the whole floor being a huge bass driver all muddled up. Everything cleans up and for the first time LOWER distortion in the BASS region.. It can be really eye opening when you go from 20-30% distortion to 5%

The only waves from that point forward are air bound and reflection points. The decay rate speeds UP. The bass frequencies become much more coherent. The boom is gone the mud is gone.

I also suspect the rest of the house will quiet down a bit.. You’re not funneling the BASS through the wooden rafters and studs, they do a good job of moving harmonics through the house..

Speaker placement will probably change a little from the old, just a bit...Getting the depth and width of soundstage is going to be easier.
Get the piano out of your lap.:-)

Regards
unreceivedogma's avatar
unreceivedogma OP
885 posts
 
Oldhbymec,

Thx, I suspect that the feet that I’m waiting for will help. I had wooden floors in the loft but the mechanical transmission wasn’t as much of a problem as the reflections were. 

Speakers in the front: I guess I’m old old old school. Not quite victrola in the corner old, but definitely showing my age. It just never occurred to me to put the sub behind the sweet spot.
b_limo's avatar
b_limo
2,271 posts
 
Thats a coincidence!  I have a really a bad bass null right where my listening position is.  Couldn't fix it for the life of me.  Tried putting my single sub 3 feet directly behind my listening seat and voila!  Sounds great.  I then started playing with placement. Moved it an inch this way, an inch that way, adjusted the crossover…. Got her dialed pretty good now.  Putting 3 GIK monster bass traps and 1 244 bass trap on the walls by the sub further improved things.  I’m using a vdlodyne hgs 10 on an isoacoustic stand and magnepan lrs speakers.

But yeah, subs behind you work well I guess 😀
ddrave44
123 posts
 
How have you set the phase delay on your subwoofer?. I have a feeling that the reason you like the placement (further back from the speakers) now is because you've got the phase delay matched at that distance so that the subwoofer signal is in phase with the fronts (albeit one or two cycles later)
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feldmen4
108 posts
 
Interesting. I just recently purchased a 2nd JL Audio E112 and had pre-wired for that sub to be behind the listening position. OMFG - the result is amazing. The soundstage is much much more 3-D like I am walking on stage as I approach the front speakers. Surprisingly, the improvement is throughout the frequency range and there is huge air between all  instruments now. I’ve been working on my system for about 5 years now and this is probably the biggest improvement I’ve had (upgrading my Node 2 to the Mytek Manhattan II is the other one that gives it a run). 
At least for the moment I feel like my system is “there” and I have no urge to upgrade further (did I say for the moment? 😎). 
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