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Because I read and think and revise, I usually avoid re-doing things before they've cost me. There have been two quite different notional projects for the final speakers before this one, too. But, I have been thinking - and hoping - about 63s, and discussing it, for a long time. Beginning well before I was lent a pair of 63s just a few years back. Asymmetric crossovers for - reinforcement of, and bass extension - under QUAD 63s, using omni bass sources (enclosures), isn't a new idea. [Using OB dipoles is a lot more recent, and NOT cheap. And I've got all these bits which say 'do boxes.'] And, there are a few imponderables yet, if you will bear with me. Will I end up using the subs for the lot @ 3rd LP from ~ 150/120 hz right on down to ELF, [or from 80 Hz and on down], and put the subs right beside the 63s?
OR do I build/adapt bass reinforcement (BR) boxes going down to 40Hz - to go right beside / under the QUADs? AND add subs just for ELF ~20-40 Hz and maybe put them in the two far corners (L-shaped room), phased to pressurise at the listening seats? Room-gain from corners is strong down low. LOTS of cables to vacuum around. I have enough spare drivers / speaker boxes, 35Hz spheres, and a spare 60WPC amp to do BR to ~35/40 Hz. In fact - this 40hz or so target, is where I will be starting. If I did go with two bass systems with two boxes for each, I'd also need to buy/build an LR4LP/LR HP xover to feed the subs!! When I have built the two subs - my tech and I will measure them, and IF I do find that the 1/3rd octave equalisers can't give me the extension I want below their Fc/F3s: to 20-25 Hz - I will apply LT Eq to match, yet retain the 1/3rd eq - to deal with room peaks, mostly. So, quite a bit of measuring, and measuring in-room to do. And several phases to the project, so we can learn about the room and stuff. 200 watts per channel (400 watts total) just might be enough for 150 hz down to 20 or 30 Hz, even with LT eq, which does chew up power! Each big stereo power amp will be running OOPhase, so this might help their PSUs to cope a bit better when running hard. IF I find that I prefer SS bass year round I'll keep the pentode 'Once was a LEAK St20' as a spare! And I may even end up preferring the big Perreaux to the valve amp for driving the QUADs, year round. Giving two 'Once were LEAKs', spare!! So far, I still doubt that I will. But it does get very hot here in Summer. The valve pre will stay, though I/we will try to add a tilt type tone-control as in QUAD's own pre-amps.
Warmest
Tim Bailey
Skeptical Measurer & Audio Scrounger
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