Sub-woofers to go with Quad 988 / 989 ?

Rhyno: I owned the Merlins VSM-SEs and used a REL Stadium II with them. The sound was seamless and gorgeous.

Have you actually heard a REL set up correctly? And, no, bass doesn't image. You cannot tell where frequencies in the 20-60 Hertz range originate. Show me scientific papers that support your claim.

The only reason front firing subs would have an advantage is at higher crossover frequencies. Otherwise, when crossing at say 80Hz and down, downfiring subs will certainly not sound "muddied" if they are designed and built properly. RELs and ACIs are some of the most musical subs out there. Used properly.

The Quads are VERY difficult to mate with subs, because most subs cannot keep up with their purity and speed. I've tried Entecs, but their cutoff frequency was too high and the X-over well to put it mildly ruined the Quads sound. So NEVER, ever use the high pass out to go on to your Quads, rather let them run all the way and find a subwoofer which cuts off sharply at 30 hz, which is the solution, which I found. Was a bitch to place it right, but then the thing worked. Bobby Carvers Signature, you wouldn't believe it, but never, ever over 30 hz. Gradient had a sub made especially for the predecessor of the 988, which was quite nice, with the Quads placed right on top. I also used old Maggie bass panels with the Quads and let them run until about 100hz. Got a beautifull bass and cello sound that way.

bass does image above 80hz, and as far as i've heard, quad's do need a sub above 60 (up to 100 or thereabouts) to provide some impact and dynamics to the sound. x-over below 100(@ 60-80) will work, and probably easier, but you won't have much in the way of mid-low bass dynamics...that's the limit of the panels. and as jd97 points out, and correctly, front firing does(!) matter @ 100hz...but he's right in that from 60 down it doesnt.

and yes, the entec x-over just sucks. the best x-over i've heard is a passive RCA type x-over, ala audioconcepts (just a cap in line to the amp inputs), but made by TG audio...1st or 2nd order (forget which) at 100hz (custom built, @ $150), passive, and transparent...which few x-overs are. plug this x-over into your amp inputs, run the subs full range via a 2nd output from your pre, and the subs will naturally roll off @ 100hz (depending on the subs), while the x-over rolls off the mains @ 2db / octave starting at 100hz. works very well.

can't stress how important it is to get the last few hz...lots of stage and size comes with it. presentation just gets huge.

one more tip: elevate the sub, particularly front firing. even if its only a few inches, but better still if its 10" and up...decoupling from the floor reduces the 'muddy' aspect found in most subs...rosenberg mentioned this once..smart guy, gone too soon.

rhyno

Seas Excel W26 + Hypex HS 200 amp. I'll post a review ASAP.