Subwoofer

@jpwarren58,

One sub can be used but definitely needs variable phase if you are limited with placement options. SVS is a great choice because of the adjustments available. It has a simple download which means you can tune it in from the comfort of your listening position via your cellphone.

In addition to phase you can also adjust volume, low pass filter, polarity, parametric EQ, room gain and presets.

You can also consider Rythmik or GR Research. there is no remote adjustment available so that needs to be done on the plate amp itself. These are servo controlled and perform superbly.

I do not understand those saying a single sub will not help. They can and do but if you just plonk a sub down where convenient then do not expect great results. You state room for one sub only and if that's the case then that's is that, but if you can squeeze another small sub in behind a couch or double as a side table or as stand for pot plant then the overall sound will improve far beyond expectations.

Even a small 8" sub will work. I use them as tuning devices and have used as small as 6.5" driver as a sub. What multi-subs do is smooth out the room response so even the little 6.5" unit that goes down to only 50Hz will help all nodes upwards from there. A 6'5 " driver in an 8" cube should not be too difficult to shoehorn in 'somewhere'

Multiple distributed subs give even, not accurate, bass at the LP.

All-Pass phase controls operate at only a single frequency with varying degrees of shift across the passband.

See 

Hi jpwarren58...

After extensive search for a smaller dedicated studio deep bass solution under 80Hz, I discovered a larger, single, Direct Servo as my solution, replacing the two sealed subs I had been using.  My Rythmic L12 was $629 delivered and FULLY delivers at such a reasonable price.  Testing shows the Rythmic loading the room at 20Hz, which I never thought possible.  Don't be fooled by the price.  I was considering one of the higher end brands, but was well advised by experienced friends, near and far.  Tuneful, solid deep bass does not have to be costly and so contributes to all the frequencies in its execution.  

Best, jpwarren58.

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A well executed sub with adequate controls* properly integrated with the mains improves the listening experience out of all proportion to the frequency response.

I ran an Audio Concepts Force with Spica TC-50 XO @ ≈85Hz rolling the lows first order from the Spicas and third order inverted in the sub.

A composer [real music with real musicians in a studio] once remarked "Those little speakers aren't putting out all that gorgeous bass?!?!?!?!?"

* multi slope XO, phase, polarity, gain. LFE input is nice if it does double duty in HT.

AND drive it low level from the pre. You don't want all those connectors and extra wire in the power amp / mains circuit!

So many variables as with all audio questions. I have enjoyed many single subs, but I was not happy for 2 channel until I got a Rythmik sub. Best sub I have heard in all regards. Wish I had believed what I read about them years ago. I’d love to hear REL some day, but I also want below 20 Hz extension with the musicality at my pricepoint.

IF Rythmik is properly dialed in, no boom in the room. Even when not, it still sounds really good, but calls attention to itself because gain or crossover is too high. Saying 1 sub is always bad, I call BS. If you have a difficult room with a lot of nodes, don’t know how to set up a sub, or didn’t get one that will sound good to you, then maybe you can only figure it out with 2 subs.  Caveat though, the only sub I have bought 2 of is the one that sounds amazing as a single sub. 

I read somewhere to buy the best sub you can afford and as many as you can afford, and I may believe that. For 2-channel, maybe 2 is the ideal rule of thumb with reasonable budget constraints. I finally hooked up my second Rythmik, but I don’t really need it in my current room. For home theatre seems like 4 subs may not be overkill to even out response at all listening positions.

The Rythmiks give you some control with parametric EQ and other settings. I’m blown away by their depth, slam, speed, and musicality, but most of all, ability to blend in and disappear when adjusted properly. I intend to integrate miniDSP at some point, but I have been happy with results adjusting sub amp settings using test tones and SPL meter. I would lean towards the best sealed SVS sub(s) I could afford with phone app EQ, if that convenience was important to me.