Subwoofers and Phase Question For You Sub Experts

@millercarbon thanks for the informative and entertaining post.
Just for a bit of context, I sold a pair of full range speakers last week that didn’t really need subs. The Dunlavy 3 is a great speaker that will cover well until I reinvest in new speakers.
I’m not new to the perils of sub integration nor the DBA theory, and I’ve conversed with Duke a couple times over the years about his Swarm arrangement. I’ve setup a few successful 2+2 systems and had pretty good results with so-called difficult speakers like Magnepan and Apogee.

So with that out of the way, to benefit from the content of your post I also need some context - I’m curious to know what your mains are and whether or not you run them full range. Also, you make no reference to sub quality, only quantity. Are you saying that 4 cheapish subs can produce tight, articulate and extended bass, or is there a requisite standard or level of quality and if so, can you suggest a make/model that you see as the entry point for a successful distributed sub system.

As for the ‘phase’ affect, I only hear what I hear and see what I see. With subs inline, I hear no issues other than that stated. With subs elsewhere, there is a downside, as stated. It may or may not be phase but it sure seems like it based on the effect that I hear.
Lastly, my pair of HSU have been pretty much everywhere in the room including perched up on table tops; presently they’re against the left and right walls, tight up and with one behind the front plane of the speakers and the other closer to the listening position.

It would be cool to hear from people using subs with inbuilt room equalization to see just how successfully they integrate in a 2+2 setup.

Cheers!

@gdnrbob
Thanks for your input. I’ve been tempted by the Vandy approach a few times over the years but I’ve never pulled the trigger on a pair. I think I’ve been put off a little by the need for placing an extra crossover in line. At least that’s how I remember them working. I’ll take a refresher on the Vandersteens tomorrow when I’m more awake!
Cheers
Rooze 

Thanks guys ^^
Erik’s first post got me interested in the miniDSP, which I’ve heard of many times but never really followed up with any research.
 I’m not sure it would be a fit for my system, though it sure as heck sounds tempting. I do a fair amount of equipment reviewing so need to be able to evaluate various DACs, preamps etc and I think the DSP would be a variable that wouldn’t sit well in a reviewing environment. One question I had on the miniDSP is - can it be setup via a tape loop on an existing preamp so it’s affect can be switched in and out?
I ran a Lyngdorf TDAi with room perfect a few years ago and it worked well, but again, for reviewing it’s not an ideal tool.

Agreed on the REL subs, whenever I’ve heard them over the years they’ve always seemed well integrated.
I’m still not certain that my main concern of managing phase would be resolved with a REL unless it’s one with 360 degree phase control and I find the patience to set it up manually (times two).
An auto solution would be awesome. 
Thanks again.
oh... for gear I have stuff coming in and out but my ‘static’ rig is heavily vinyl and tube:
Music Hall MMF-11 soon to be replaced with a new Origin Live setup
Manley Chinook / Zesto Audio Andros
Thor Audio tubed Pre and Power 
Aurender N100H
Sim Audio Moon 380D DAC
other odds and ends

@jaytor great suggestions, thanks. I had a set of the Carver Amazing Platinums with their open baffle bass system and though blending with the ribbon was flawed, the bass could be made to sound very good. 

I’m familiar with the GT Audioworks subs having heard them at Cap Audio Fest a few weeks ago.
I’ll check into the Rythmik Servo approach and GR Audio’s implementation, if I’m not mistaken GR has a presence on Audiocircle so I’ll take a look.
Thanks

Rooze

@millercarbon

”Mains are Talon Khorus X. Not that it matters”
It matters to me, or I wouldn’t have asked.

@audiozenology
I have them crossed around 60hz but I’ve experimented quite a bit with different settings. My room size is part of the issue, 17x16 x 8.5 ‘
Point taken about bass arrays and the mic investment.

cheers

Rooze

Wow this has turned into a great thread. I was a little concerned about it going off the rails early on, but it hasn't.

Thanks to everyone who has chimed in so far and keep the ideas coming.

My take away so far is mostly derived from an earlier post from Audiokinesis:

1 - Get the room as 'tuned' as possible using conventional bass traps and treatments.

2 - Then, utilize one or both of EQ/DSP and DSA to dial-in the best response. As Duke says, smooth bass = fast bass.

Then things get a little more subjective around the following:

1 - Time-alignment is a non issue due to low frequency wavelengths. I can see the physics of this argument yet there are others in the know who disagree. Lyngdorf for example (The TACT spinoff) factor for sub positions and have a delay factor for the mains built into their DSP or 'Room Perfect'. Perhaps that's a novelty or selling point and nothing more. I don't know.

2 - Phase control. Is it an issue or isn't it an issue? In my OP I was asking whether or not DSP factors for phase alignment and the consensus has been that it does not. Some of the more upmarket subs have 360 degree control where others simply have a 0-180 toggle. REL, known for their 2-channel prowess offer neither on their T/7i, which is aimed at the 2-channel market. So what gives? I suppose their answer would be to flip the leads on the amp binding posts. (high level)

My choice of the word 'phase' when describing a specific issue was perhaps misleading. Maybe it's a phase issue maybe it's something else.

Just to describe the problem a little more fully -

I have my mains about 75 inches from the front wall and with the mains only I get an excellent perspective, sense of depth and space, and very focused imaging. By perspective I mean that the soundscape is almost entirely behind the front plane of the speakers and extends through the front wall and beyond the outside boundaries of the speakers. The bass from the Dunlavy, in my room, is poor in two ways. Using a test CD and SPL meter, the extension from the sealed box speakers is good into the 45hz range then rolls off quickly. There are dips around 70-130Hz, again at 150-170Hz. I can clearly hear those on certain tracks.

Adding a pair of subs on the outsides of the mains, about an inch or so forward, helps to flesh out the bottom end and mid-bass, but the subs are obviously affected in the same way as the mains by the room modes and the frequency response anomalies.
So it's still far from ideal, but - the attractive imaging and soundstage properties are maintained. There's no negative effect. There's a positive effect but it isn't 'problem solved'.

So moving the subs and placing them by ear/test to get the best and smoothest response at the listening position I end up with the right channel sub about 2 feet behind the right main and the left channel about 5 feet in front of the left main, both up against side walls, both well away from corners and neither firing directly into a wall!

In this way I get a smoother response all the way through the frequency range. Not perfect but better. However, the depth and width of stage is diminished and I lose the laser-like focus of images in the soundscape. There's almost a smearing affect where the air and space around images diminishes and that's what I'm referring to as a 'phase anomaly'.

I've moved the mains to and fro ad nauseam, as we do. I can get a little better response closer to the front wall but the perspective and depth is diminished and I don't want that.
I've tried different listening seat positions, obviously. 
I've tried sub placement all over the room and messed with phase toggles (0 or 180) and right now I seem to have the best compromise. But I'm not entirely happy with it.

So if the above is something other than a phase issue I'm happy to stick a new label on it and I'm all over any ways to fix it that don't involve bringing in more gear!

Since posting this thread I've written to a couple sub manufacturers to see if they'd come up with some comments and perhaps even loan out a quad of subs so I can set up the DBA and write the process up as a review. I doubt that will go anywhere but plan B is to go out and buy two or four subs on the used market.
All of your comments are helping and my trigger finger is twitching, but I'm not quite ready to buy more subs just yet.

@m-db 

Rooze, way off topic questions.
What model phono cartridge are you using and what did the Zesto Audio Andros bring to your setup?

m

Using a ZYX Ultimate and the Zesto is great!! Actually just posted a brief review of it earlier today... maybe you saw that?