Power amp for Quad 988s

Which c-j tubed poweramp is underpowered? How big is your room? Musical tastes? Desired loudness levels? Subwoofers? Running 988s full-range?

HELP US HELP YOU!
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Jeffrey, I obviously should have provided more information. I have an old CJ MV-50 that I have had for 20 years along with an old ARC SP-6B with a Monolithic phonostage and VPI Mk III/PT-6 and Grado Sonata.

My room is about 15' X 20'. I listen to a wide variety of music but I tend to focus on jazz and vocals for my more serious listening. So, transparency, midrange accuracy, microdetail and what some TAS reviewers call "continuousness" are important to me. I am not as interested in the last word in high or low end. I don't listen at high loudness levels, and do not use a subwoofer although I have thought about it.

My main problem with my current electronics is the bloated bass sound and lack of tightness in the bass. LIke I said, I don't need to hear bass at 35hz since quads won't go that low anyway. But, I want tighter bass and know that my older electronics are not bringing out the best in the quads.

Thanks for any input.

OK...some observations for whatever they're worth.

1. If you think you love the lush, musical richness of EL34 output tubes, consider a new MV60. Not only does it have about 1-1/4 deciBels more power (60 Watts instead of 45), it uses the same larger output transformers as the 70WPC Premier Eleven. PROBABLY it will have tighter bass.

2. If you think 1-1/4dB more power isn't quite enough more, consider a Premer Eleven-A at 70WPC and 2dB. It's VERY popular, fairly common, and fairly affordable at c. $1500. If it turn out to be not better enough, you can always sell it for what you paid for it.

3. Consider refining the sound of your room, with, for instance, Tube Traps or similar products. Does your room have several triple-90-degree corners? Most have, and as many as 8! Eliminating them with corner 'plugs' will help. Where are the speakers and where are you in respect of the bass nodes? Are you sitting at a peak, ie 1/4 of the left/right or front/back dimension?

4. Consider a dipole woofer such as the Gradient SW-63 that was so popular with the Quad 63s. See http://user.tninet.se/~vhw129w/mt_audio_design/quadpage.htm . They used, IIRC, 2 10" drivers and also acted as speaker stands.

Lots to think about. Good luck.

BTW, I'm using Quad 989s driven full range by Antique Sound Lab Explorer 805 DT poweramps, 50-Watt single-ended triodes. My room is 21' wide by 19' deep by 6-1/2-to-12' high, with very little wall surface parallel. (See the pics in my System.) I listen to large-scale classical and film music, and those amps will drive the 989s JUST loudly enough to invoke the speaker-protection circuitry if I accidentally turn the volume UP instead of DOWN.

Thanks Jeffrey. Alot of good suggestions. I have always liked the CJ/EL 34 sound until recently. I think I just bought into the idea that with the low sensitivity of the quads, I needed more power. But, as you point out, maybe with some room treatment and a tube amp with a little more power and a larger output transformer, I can keep the lush CJ sound but add some tighter bass.

I definitely should consider room treatment. I have 6 triple 90 degree corners....a funky room. I sit about 7 feet from the speakers which are about 5-6 feet apart.

I actually did look at your system after your first email and noticed that you were using the ASL SET poweramps with the big Quads....so no reason I can not find a tube amp that gives me the midrange I want with just a little more tight bass.

I am definitely going to consider the Gradient subwoofer. I thought about it when I first got the speakers but just never pulled the trigger. The quads with more bass might be something to behold.

Thanks again for your help.

You are very welcome. One caution--I have NO idea if the 988's base size is compatible with the Gradient. Do look carefully at that.

I've done very little room treatment. Fortunately what I did to a 14x19x8' living room in 1982 turned out to be VERY listenable.

Filtering a little bass out of the Quads will increase their power-handling capacity too. A single-order filter point of 30 or 40 Hz might help a lot, and that can be done very easily with one series capacitor. In fact, years ago I had some requirement to have some bass filtered out of a poweramp sometimes but not other times. I changed the existing filter cap to a smaller value that achieved the high-pass filtering but then added a larger one in parallel but with its input switched. With the large cap switched in, I had a full-bandwidth amp; with it switched off, it was an '8-octave' amp. Worked very well.
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