Dual subs for 2-channel system: placement, cabling, matching

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dmn

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Topic has been addressed on this & other forums, but would still like some advice on my particular puzzle. Current system is balanced B&K preamp/amp, KEF 104s, OPPO 103 as CD transport, and Bluesound Node 2. Listening room (originally a living/dining room since abandoned by family preference for a great room, now my office + music room) has dimensions (26 x 13 x 8) that can create nasty room modes for the listening position (moved 11.5' from front wall to get away from center of room, not much flexibilty). GIK corner traps on front corners are only room treatment. Looking for more but not really loud bass accurate down to 30Hz via 2 subs.Just got a Revel B110 sub: small at 10" but attractive for its modest size/weight, sound quality, connectivity (XLRs in/high pass/out to second sub) and good DSP software for bass management. Lots of conflicting advice out there on 2nd sub placement: front corners, front 1/3rds, front/rear or side/side midpoints, diagonal corners, all with caveats that each room is different.Connecting or even testing a 2nd sub in a F/R or diagonal configuration requires a 35-45' cable crossing some big AC cables along the way so I think XLR cable (BlueJeans?) is necessary, requiring a 2nd sub with XLR input. I would mostly appreciate suggestions on 1. Sub placement for this room, and 2. Options for 2nd sub (driver size/ models), along with guidelines for avoiding likely null point issues. Many thanks in advance.

JLM

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Re: Dual subs for 2-channel system: placement, cabling, matching
« Reply #1 on: 16 Jan 2018, 12:45 pm »
Suggest reading Floyd Toole's "Sound Reproduction" to learn about in-room bass behavior.  Toole describes bass waves as acting like waves in a shallow bathtub.  Bass generated at one end will move along the length of the room, like moving your hand from end to end in the tub would create a wave.  As the wave reaches the end it will rebound and hit the next wave and either add, cancel, or some combination of the two.  As frequency and location varies so does where this interference will occur.

Can you shorten the room to achieve a better shape (because what you have now is a giant tube and the width/length are in a simple multiple and will increase echo)?  My room follows the Cardas Golden Cuboid ratios (8ft x 13ft x 21ft), I'm very satisfied with it, and it barely benefits from treatment (six GIK 244 panels that are very effective elsewhere). 

My system is 100% balanced.  Love the cheaper inherently shielded cables that avoid all the cable marketing voodoo and lower noise levels of the gear itself.  So Blue Jean XLR cable would be fine.  To be honest shielding concerns are way over done in home settings.

Recommend setting up the 2nd sub at the far end of the room.  With your long room, diagonal setup would have little effect.

Look into wireless subs/add-ons and wireless subs with feedback microphones for easy setup.  But above all buy a quality sealed sub like a SVS SB-1000 or Rythmik L12. 

Carl V

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Re: Dual subs for 2-channel system: placement, cabling, matching
« Reply #2 on: 16 Jan 2018, 04:37 pm »
you might also want to read this book/watch VDV
or at least go this site.


http://getbettersound.com/index.php

poseidonsvoice

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Re: Dual subs for 2-channel system: placement, cabling, matching
« Reply #3 on: 16 Jan 2018, 05:22 pm »
dmn,

To avoid repeating myself, I have already answered your questions in an earlier thread here:

http://www.audiocircle.com/index.php?topic=155030.msg1659006#msg1659006

Pay particular attention to the link on Step 9 which goes over the various methods of multi sub implementation from Toole, Welti, Geddes, etc...

Best,
Anand.

dmn

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Re: Dual subs for 2-channel system: placement, cabling, matching
« Reply #4 on: 16 Jan 2018, 09:55 pm »
Many thanks for input from you forum vets. My responses:

JLM- I am familiar with bass behavior/management from prior HT systems. Toole/Welti are/were Harman guys. Harman/Revel Low Freq Optimization (LFO) program incorporates much of their approach (but comes up with some different recommendations at times). Budget/room limits subs to 2, stretch to 3 max. Room dimensions are fixed & the simple L/W multiples so hard to fix. Good to know that diagonals (& probably any front setups) unlikely to work, so will start planning based on your plug for F/R which worked well in prior 7.1 HT in same room. Bad hum/RFI with long RCA runs before, cured by digital cables in Meridian system. So will try those BlueJean XLRs. I don't understand why more subs don't have XLRs given frequent need for long runs to rears.

Carl- bought the book at your rec. Always lots to learn.

Anand-read/appreciated your prior thread. Long ago I tried REW but got overwhelmed by measurements & complexity. Meridian Room Correction program with their 861 pre/pro gave simpler great bass management solution for all digital HT with very large fronts/center, large rears/sides, & 2 subs F/R. Sold that system, starting over in same difficult room with analogue stereo + subs on low budget. Will apply the superb guidelines from HIFIZINE articles while trying out the Revel LFO to see how far I get.

I am going to get a good mic & test room bass with Revel sub as near to center front as I can get (18" off, don't know how significant this may be). Will update thread as results come in, but meanwhile please keep those insights & suggestions coming.

   

Speedskater

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Re: Dual subs for 2-channel system: placement, cabling, matching
« Reply #5 on: 20 Jan 2018, 02:12 pm »
With good AC power cabling and good interconnect cables, power interference is less of a problem than many think. 3 inches of separation is all that is often needed. Now light dimmers and creative power wiring can be a different matter.

* * * * * * *
In fact, one of our members (who is a day job expert with wire & cable) does some weekend DJ work. He tapes the long AC power and the interconnect cables together on a big reel.