# subs under couch



## pietsch288 (Sep 10, 2006)

Do I still need to put the couch @ 68% of the room if the subs are under the couch?? I have discovered that I like the bass and can control it much better if the subs are under the couch. I have all 4 corners trapped and first reflections. Room is 23x15'7"x9'6". thanks


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## bpape (Sep 14, 2006)

Generally, it's between 62 and 66%. Where the sub is has no bearing on where you sit in relation to avoiding room mode issues. Must be some skinny subs to fit under a couch.

Bryan


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## glaufman (Nov 25, 2007)

In addition, I would suspect, and ask Bryan to confirm/deny, some additional benefit from locating the sub(s) with a similar percentage rule...


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## bpape (Sep 14, 2006)

Sub positioning is the big trick. It has to:

- blend with the mains
- provide smooth response
- be in a place where it's not localizable
- be able to be in phase with the mains (which is the real kicker with only a 0 or 180 switch as opposed to a fully adjustable phase control)

Remember that you can move a sub in 3 dimensions, not just 2. My general suggestions are:

- Try to keep the sub close to the mains if possible
- Start out with the sub at a prime fraction of room dimensions (1/5, 1/7, 1/11, etc. from front wall and side wall). So, maybe 1/11th of the room width and 1/7 of the room length. This is not a perfect solution but it will get you decent response and a good starting point by not sitting at any particular modal point.

If you have 2 subs, try 1 center front and 1 center rear as per the Harman research.

Bryan


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## pietsch288 (Sep 10, 2006)

The subs are 4 cs ultras, they are 17" round, the risor will be 17 1/2" clearance. I have 9'6" cealings so I can have a tall rear risor and a shorter front risor to pull it off. When I had the subs front and rear center (per the Harman research), the bass still didn't seem right, so I Put 2 behind the couch and two in front of it (lying down) and was very pleased with how they sounded and felt..... but as you can imagine I was dissappointed with the looks. That is the reason for the tall risor. I do have an SMS-1 with fully adjustable phase and my receiver has audyssey.......Should I let audyssey set my subs???????????????????? thanks


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## glaufman (Nov 25, 2007)

You can also try 1 left center and 1 right center...
Or do you have 4? Try 1 centered on each wall.


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## pietsch288 (Sep 10, 2006)

I am running them all off of a ep2500. So that means I have to pair them up to keep the correct ohm load. I tried 1 center of all 4 walls and that didn't seem to work well......sound or looks. Shouldn't audyssey set the phase correctly for me? I have a 9v batt so I should be able to handle all the sub wiring.


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## bpape (Sep 14, 2006)

Ar you sure that when you paired them, that you had both 'sides' together and both ends together? I assume that's how Audyssey would attempt to do that, one channel at a time.

Bryan


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## pietsch288 (Sep 10, 2006)

Shouldn't I have to start with the front sub and then the rear (setting the phase accordingly between the two) then the right sub (setting the phase with the other two) and finally the left sub (setting the phase with the other 3) because that is what I did. When I had two up front and two in back I would have to run them @ 180 o. So I assumed that I could not run the front and rear in the same polarity because I loose most all of the bass.....the graph looked pretty good ( flat) when I had them split @ all 4 walls but it was down 10-15db easy if not more, with no feel.....wierd--didn't take long to get back to the front-rear thing (I read in the white pages that front and rear is almost identical to 1 center of all 4 walls....so I focused on what I could control (or at least seemed like I could not screw up). But I doubt I tried the front and rear "hitting" at the same time and each side "hitting" at the same time. If you swore that setting the subs like that would be "night and day" from 2 up front and 2 in the rear....I might give it a try, but from what I read..... it sounds like marginal at best.


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## pietsch288 (Sep 10, 2006)

All right now were talkin.....risors are built, subs are under/ working and other than a few little finishing touches pretty much got er done. I just have to say straight up that its awesome.....I could have never imagined that I would be this happy with the results, and I still haven't rerun audyssey. I put in ironman with no changes to eq's -volumes- xovers so I could make sure the results, after playing a bit I am running them bypass (on the SMS-1) with no eqing or xover....and and and I used to have the volume on the sms-1 @ 45-50 now its at 26 (unbelievable). I do have to say that with the subs under the couch I get somewhat of a buttkicker feel except I can feel and hear the energy of the room (can't get that from a buttkicker) I'll do audyssey and more demo's tomorrow (must sleep now). thanks for the help


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## bpape (Sep 14, 2006)

Well, if the 2 sides aren't set the same as far as phase, I'll guarantee you it's not right. They're the same distance from you and from the main subs, the phase HAS to be the same. Front and back together may not be the same assuming you have infinitely adjustable phase and not just 0 and 180. If just 0 and 180 and you're around 62% of room length, they should be the same.

Bryan


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## pietsch288 (Sep 10, 2006)

When I was messing around with subs alot.... I borrowed 2 of my buddies pc ultras (they have a plate amp and full phase control ect) they were in phase @ the 180 (front and rear subs). So I used my cs ultras as the front -rear (front sub @ 0 and rear sub @ 180---- reversing polarity on the behringer amp) and his pc ultras on the sides. From what I can remember It didn't seem to matter at all where the phase was at on the side subs (and I really did spend at least 2-3 full weekends and a couple of week days trying different things so I must have at some point at least accedently had it correct). So after what seemed like months of endless screwing around...I pretty much just gave up and stuck with the 2 front 2 rear thing. I didn't feel like I was gaining anything and it looked like I had subs everywhere (subs in the middle of all 4 walls is tough to pass as DECORATIVE or MODERN with the wife and I didn't think it look very good either). Now that said If it would have turned out to be the holy grail of sub setups you can be sure they would still be there. merry Xmas Brian, thanks for all the help over the years!!!


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## glaufman (Nov 25, 2007)

pietsch288 said:


> So I used my cs ultras as the front -rear (front sub @ 0 and rear sub @ 180---- reversing polarity on the behringer amp) and his pc ultras on the sides.


Well, I don't remember what the cs ultras are, but if the capabilities are different than the pc's, that can explain what you saw. Mixing subs of different capabilities without limiting their frequency ranges usually doesn't provide much benefit above where the lesser of the subs would be by itself...


pietsch288 said:


> If you swore that setting the subs like that would be "night and day" from 2 up front and 2 in the rear....I might give it a try, but from what I read..... it sounds like marginal at best.


I don't swear anything. But the studies I have read indicate that for maximum flatness across the frequency bands across multiple seating locations, in a regularly shaped room, this is a good rule of thumb. That's not to say that other things will never work better in any given room, so YMMV.


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## bpape (Sep 14, 2006)

Probably going to drop off for today and tomorrow. Hope you all have a great holiday.

Bryan


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## pietsch288 (Sep 10, 2006)

The cs ultras are the exact same as the pc ultra..... minus the plate amp.


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## bpape (Sep 14, 2006)

And without the plate amp, you don't have the infinite phase control nor the same response curve built into the amps. Yes. Sub plate amps have some EQ built into the circuitry usually to compensate for the specific driver they're mated with.

Bryan


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