I would always go with two or more subs. That said, just putting two or more subs in without a crossover and then phase aligning them (individually) will not allow you to get the maximum benefits.
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Could you elaborate?
Obviously each sub can be phased from 0 to 180, but does one make that call only by how it sounds? Or is it more scientific than that?
What should one listen for?
I had a couple of SVS PC subs that I had for 1 year then sold. The next owner also had those issues with both his plate amps after another couple years of service.
They do sound amazing in theater though. Never did use them in my 2 channel setup.
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You can read the how and why at soundoctor.com. It is a very technical article but reading several times will help. The basics of the article is to use a crossover to make the subs subs and your speakers the mains (a true mains and subs setup). Otherwise you are just adding subs without the full benefits. Now with the crossover (JL Audio suggests crossing over at 80 Hz. Sounds high but trust me it works) in place you can do the phasing (I’m leaving other setup parts out but the article covers them). Phasing is done by doing one pair sub/main at a time as follows. Play a test tone through the one channel pair at the crossover point (say 80 Hz). Get between the sub and main’s woofer and adjust the sub volume to match the mains. Then put the sub and main out of phase (switch the speaker cables on the the main). Now play the tone again and where the frequency becomes weakest or nulls, that is your phase setting. Remember to switch back the speaker cables. Then you can adjust the sub volume as desired. There are more details as I said, but this is the basic. It is a game changer for subs.
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SVS ,told my that There is no issues with their plate apps that they are very reliable. thank you for your response I didn’t think it was just me ,and to go through so many plate amps is very unsettling they are still on warranty but I think I am going to put them up for sale with full disclosure about the amp issues at a extremely reduced price. I just don’t wanna deal with it anymore I will pick up another pair of RELs.
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Dredging this thread up as I’m starting to mull this over in earnest now.
So, this is the space with the Magnepans. Audio system is in a closet behind the orange couch, and speaker wire and RCA’s for the subs run under the rug. I don’t have little kids or a lot of traffic in the room, so not worried about the cables getting stepped on or damaged under the rug. It works fine. Not true audiophile, but here we are.
Currently I have two little Cambridge Minx X201 subs behind the Maggies. One white, one black because that’s what I happen to have already. 
They fit between the legs of the speaker riser, and when I’m having a listening session, I pull the speakers out from the wall. Subs stay where they are.
So, I’m thinking of getting some more substantial subwoofers, and they would remain in this location. They would be bigger than these little Cambridge subs, and wider than the Magnepan feet, so I have two options.
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Build a little riser/base/pedestal for the sub so it straddles the feet. When I pull the speaker out, the sub would stay put.
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Build some kind of riser that would ATTACH to the Magnepan feet. So the sub would be connected to the Maggies, integrated with the feet, and would come out from the wall when I pull the speaker out. Think of a sled. (I built those Maggie feet out of walnut, so I can easily fabricate something, also out of walnut.)
I could sketch something up but hopefully you get the picture.
So, two questions:
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Which of those two options seem the most viable/desirable? Visually, to me, it’s a horse apiece. Sonically, I don’t know what’s better. Either option will raise the sub off the ground, but will coupling the sub with the maggie legs create some unwanted harmonic something or another? Is pulling the sub away from the wall favorable in the same way as speakers away from the wall?
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Need a sub recommendation. Looking at REL T7i, SVS SB2000, others. Nothing bigger than 14-15" square. If something came in a walnut finish, that would be awesome. For connections, I could go either RCA (as there’s already cabling in place) or I could go from the magnepans’ speaker terminals to a high-level input on the sub via a jumper. (At least I think I can do this. I never really knew this was an option until seeing a thread here a while back that referenced it.) So, high-level inputs are fine, but not critical.
Amplification is a Parasound HINT6 integrated, for what it’s worth.
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Hey @terzinator,
Subwoofers typically couple more efficiently to the room when loading into “quarter space” up against a wall. My vote would be for a solution that left the subs stationary back there.
If you have suspended floors beneath the hardwood I see in the pics, siting the subs on soft isolation footers or a rigid platform with said footers beneath it will offer sonic benefits. Capable “true” subwoofers (Sorry, your little Minx mid-bass boxes wouldn’t qualify! 
) with all drivers situated on one face of the enclosure have a propensity for making suspended floor construction sing along with heavy low frequency music content- like a gigantic droning kettle drum. Not a good thing. So the addition of isolation footers to whatever subwoofer you decide on will likely provide the clearance you need to slide the Maggie stabilizer feet beneath the sub when domestic harmony requires.
Yeah, if I go with the “subs stay put” option, I’ll likely rise them up on some kind of massive platform. Not massive sizewise, but massive in that it should cut down on resonance to the floor below. (For what it’s worth, It’s right next to an exterior wall, as well as a fireplace, so there’s lots of foundational support/deadening. I’m not too concerned.)
Forgot, also looking into Rythmik subs, along with REL and SVS.
I would go the route of keeping them separate and lifting them off the floor at least 6 inches. I have all sorts of tube traps and acoustical treatments in the room. The most valuable treatments are sub traps that lift my subs 18 inches off the floor to minimize room nodes vertically. Also isolate the sub from the floor.
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Awesome set up kitdog! Two subs or more is the only way to go! I need to get a CR1 in my set up to take my system to the next level!
Thanks.
I’m sold on the CR-1 with JL subs. However, there are other good choices.
I have the F113’s. I think the CR1 will give my M700’s more headroom on my main speakers by eliminating the low frequencies.
No doubt. My mains have four 12s in each speaker. I crossover at 80 Hz
and at 24 dB per octave, this eliminates quite a bit of load on the monos.
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Unless he goes four, anyway.
Very true. Anything is better than just one.
Get the RELs! I love REL and JL Audio, cant go wrong with either of these brands.
thanks.
Just so we can put a bow on this, I did get this dilemma sorted a while back with two REL T/5i’s.
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Since you say this solution has sorted out your dilemma, I assume you’re pleased with the results. I’d be interested in any impressions you care to offer. I have .7s as well, and have been augmenting them for almost 3 years now with a single, old (12-15 years) Hsu. It does the job, but I feel like it could integrate better, and it’s prone to producing peaks and nulls around the room, so I’m kicking around the idea of upgrading to a newer unit, either singly or, preferably, a pair. Like it did for you, the REL website’s “sub selector” routine said the T/7i (and now T/7x) was the appropriate match, but the cost of a pair of them puts me off. I sent a note to REL, describing my room, equipment and intended use (music only), and asked their opinion which would be better - a single 7 or a pair of the 5s, and they answered, perhaps predictably, that I should get a pair of 7s. 
To their credit, they had practical reasons for recommending a pair over a single sub - primarily centered on the fact that I have M700s and would have to use the line-level input if I got a single unit. Still, I was a little disappointed that they didn’t address any sound differences between a pair of 5s and a single 7 in their reply.
ah, well, a few things have changed, and so I guess I should update this.
The listening space in question now has (as of Jan 2021) Harbeth 30.2 XD’s, amplified by (as of Sept 2021) a Luxman L509X integrated. The subs are very subtle. I don’t need too much bass, frankly. I could probably get by without the subs.
The REL’s are fed by the speaker cable directly off the Harbeths. I have the crossover on the sub set very low, and the volume set higher.
I’ve moved the Magnepan .7’s downstairs, and there I have a pair of T/7i’s. Very small space, and I don’t really need the REL’s down there. In fact, the Cambridge Azur integrated doesn’t really like them set up for high-level. Goes into protection after about 10 minutes. Could go back to low level, but I’ve unhooked them for the moment. Need to sort that out.
Just for fun I might move the T/7i’s upstairs and the 5’s downstairs. That would be more appropriate to the room size and speakers.
Honestly, the only reason I haven’t already done that is because of visual aesthetics. I want white subs in the living room and black ones in the downstairs cave. 
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