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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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feldmen4
110 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? 😎). 
dizbuster
40 posts
 
I read an interview with Dr. Hsu of Hsu subs where he stated the best place for a sub was behind the listening chair. Works for me. You mentioned listening from your desk. I found that ccktail tables (flat surfaces) anywhere in the listening area mess with the imaging. I've moved a table about a foot left and right and the vocals would move accordingly. Said table is gone.
anders65's avatar
anders65
17 posts
 
I share a similar experience. Tried the "crawling" method trying to find a good placement for the sub according to what I could hear. But I could never find a location for the sub that sounded good in the listening position. This method may work well in some cases, but not in my room at least. Maybe it works better with multiple subs?

Anyway, I took another approach. As my room suffers from room modes along the listening path and especially at one frequency around 31 Hz, I decided to try to cancel out a high pressure area caused by this room resonance. I used a sinus generator that is a part of the RAW audio measurement PC software to generate a 31 Hz sinus signal. Connected the Laptop to a USB DAC, amplifier and speakers. I found a high pressure area just few feet behind the listening position. I placed the sub there. Then I listened at this location of the sub and fine-tuned its position, level and phase so that the sound pressure in this position was similar to other non-resonant frequencies. The possibility to fine-tune the phase of the sub was an important feature to be able to cancel out the pressure. I should add that I use floor standing speakers that goes down to about 27Hz -3dB.

Finally, I got good base in my listening position without using any bass traps (tried that before with minor success). Later I verified the frequency response in the listening position using a measurement mic and again the RAW software. The frequency response in the lower end looked really good with the sub and the settings I have made by this method.
unreceivedogma's avatar
unreceivedogma OP
919 posts
 
Ddrave44:

The only control on the 15” Velodyne ULD II is a volume control. That’s it. It is set 50% lower now.

I have a BBE282ii to adjust the phasing, one for each channel, but those are between the preamp and the sub’s servo/amp. The sub’s servo allegedly has a computer that makes 3,500 adjustments per second based on feedback coming directly from the driver.
unreceivedogma's avatar
unreceivedogma OP
919 posts
 
Andrs65:

I am not familiar with the technology that you are using. I’m just glad a light bulb finally went off in my head about putting it behind the “sweet chair”.

I thought: the sub sounds the best in its old spot between and slightly behind the mains when standing next to it, so why not move it next to the chair? Makes no sense to put it in front of or to either side, so it had to go behind. 

Not that the logic I employed here is in any way correct.

A distinguishing feature of the room shape is that it’s not rectangular. It’s two triangles cutting into each other, one larger (the overall roof), the other smaller (the gable). And then there’s the two dormers.
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