Two Subs?

10-15-13: Rockyboy
Got it! Thanks for the explanation. Hookup of current REL is via the speaker terminals. Dealer did the hookup upon delivery of my monoblocks. He says I'm precluded from wiring to my amps because they have a floating ground. So, a second REL will be wired to second speaker. Apparently, not optimum.

This doesn't make sense to me. Whatever problems might result from connecting the sub to the output terminals of the amplifier, as a function of the internal grounding configurations of the sub and the amp, would also occur if the sub is connected to the speaker terminals.

Is/are the amplifier(s) the Essence Jasper mkII monoblocks referred to in your system description? And are they "fully balanced," as far as you know? In particular, do their negative/black output terminals have a signal on them, as opposed to being grounded?

Regards,
-- Al

I don't think you need 2 subs unless your mains are extremely challenged...summing the left and right signals in the "high level" input of a REL and setting it at around 55 hz or so (or wherever your mains start to drop off) is all the bass you might need, but, of course, this is entirely room dependent. Multiple subs can get more standing waves and/or phase issues ramped up, and I prefer keeping my sub away from the gear. I am anti room correction device due to my inflated Professional Sound Mixer ego, and can (and do) adjust my REL level if it's out of balance. I think room correction gizmos are there for those who don't seem to be able to turn a sub up or down, insist on listening at extreme levels, the listening room is in an underground cavern full of medieval torture devices, bats, and dripping with moss, or simply feel so insecure about system set-up they require an electronic helping hand.

Two or more subs are mostly for balancing bass levels more smoothly across a room, not so much to get more or better bass at any one particular spot, though it may well help achieve properly balanced bass levels more easily there as well.

Duke from Audiokinesis is a proponent of using more bass modules for this purpose of helping to randomize bass modes throughout the room better. Of course, any pair of larger full range speakers do this to some extent, but best choice of placement for bass may not always be the best overall.

AK planetarium systems use 4 separate "bass modules" to help achieve this for example. This makes a lot of sense to me and the AK Planetariums are high on my list of potential high value speaker systems (especially for more problematic rooms acoustically otherwise) I want to hear someday.

As one who lacks PSM ego (tho I've got more than enough of the garden variety sort to offend most folks), I do use room correction. Attendant to that task, I've generated tons of readouts from my RTA that show FR at the listening position. Two subs generally produce notably better "looking" readouts at the listening position than one sub, prior to EQ. After EQ, two EQ'd subs probably produced better results than one EQ'd sub over a wide area - tho results at the listening position were awfully close. I say "probably" because the comparison is really dependent on how you define the "wider area".

I also emphasize "better looking" than "better sounding" only because the latter is subjective. However, to my ear, the results definitely correspond to the readouts - I much prefer the articulate bass sound of smoother FR at the listening position. IME, smoother response comes with multiple subs and/or room correction.

Just my own experience, FWIW.

Marty

PS - re: Bob's comment on the high level REL x-over scheme. There are advantages to inserting an active x-over that you forego when using REL's scheme. Believe what you will regarding the claimed benefits of REL's scheme, I'm pretty sure that Bob was expressing his own strong preference for actively crossing to the subs ahead of the power amp.