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In Reply to: Hooked up a QSC amp & questioning my mental state. posted by soundnut on April 26, 2007 at 17:32:00:
Model QSC running my Analysis Omega planar/ribbon speakers. I have had Thresholds, Brystons, Atma-sphere, Spectron, (all of which I own), Hurricane,Cary, Levinson, Art Audio (beautiful sound but just not enough power for the panels) and some others that leave no real memory.The QSC, coupled with the Spectral DMC30S preamp, outshines them all. Granted, the Atma-sphere was at a dissavantage due to the panel's impedance. But the QSC beats each amp at its own game! Better bass control than the Spectron with Sense Cable, better and smoother highs than the Thresholds (the t-holds might be a tiny bit better at very soft levels...maybe...but not at volume), more slam than either the Bryston or the Spectron, and better mids than the Bryston (which, in my system, was always a relaxing and enjoyable thing).
Clarity, soundstaging,foot-tapping timing, imaging, dynamics Macro, and amazingly, micro. But what shocked me and my friends were the tonal qualities in this system. And the tonal balance doesnt change when the going gets tough. You have to get to gross clipping to notice any change or sense of strain in the amp. At 900wpc,into the panels impedance, I never get to gross clipping unless just being insane.
I have noticed the same thing as another poster here, that many high-end amps,for instance the Thresholds, in direct comparison to the QSC, seem to sound compressed even when running well within their power rating.
I am leaning more and more to pro gear...there is a much better bang for the buck, and in the real stuff, great quality control and robustness.
Give Me Ambiguity or Give Me Something Else!
Follow Ups:
did you have with 900wpc?Just curious.
rw
The 900wpc was for the QSC. I apologise if the post was not clear.
Give Me Ambiguity or Give Me Something Else!
If you found use for the extra 9 db afforded by the QSC amp, then I'm not at all surprised you found favor with the unit.rw
though I do admit it is nice to have that sense of macrodynamics on big music. Hearing more realistic drum thwacks, with all the overtones intact, whilst a flute is doing its thing, is pretty amazing. The QSC gives these panels a good deal of a horns attack, with what I consider to be the better coherence behaviour of these panels. All part of the trade-offs we make....The ability of the QSC to handle major bass notes while not losing any of the high frequency stuff is much better than in the T-200. I suspect that it may have to do with the much faster recovery of the switchmode power supply over the linear one.
I am not saying the QSC is the Second Coming of amplifier design. I would not be suprised if on more efficient speakers, the T-200 might end up ruling...as long as the amp never needs to go past 1/8 throttle it may prove superior on fine detail and harmonic structure. Or not. Same for the Atma-sphere amp; give it the speaker load it wants and it no doubt could cream the QSC. But on difficult loads requiring power and control, the QSC rocks.
Give Me Ambiguity or Give Me Something Else!
Well if I am not mistaken your Analysis Omegas are not a particularly difficult load. 4 or 5 ohms, pretty darn flat and largely non-reactive load is it not? About 87 db/watt sensitivity as well. Ok, the Art audio is definitely at the lower limit. The Atmasphere was also probably not delivering much power into this load (maybe only about 20 watts).However; either you have a very large room or like to listen insanely loud to need 900 watts from this speaker. You will have long before reached its dynamic excursion limits. To reach 100db should only require about 20 watts of clean power (that's for a stereo pair at about 4 meters away). My guess is that it is peak rated up to about 110db which still would be well under 900 watts (more like 250 watts).
BTW, I do agree with you that a lot of amps sound compressed even well within their limits. I am surprised to hear that the QSC does not sound this way.
*
Music making the painting, recording it the photograph
...have noticed the same thing as another poster here, that many high-end amps,for instance the Thresholds, in direct comparison to the QSC, seem to sound compressed even when running well within their power rating.Well within their power rating. As determined how? The '81 Stasis I use in my vintage system does not clip gracefully. In its current home, that is never a consideration because I run it at <10 watt levels.
rw
I can answer that by a couple of things...1)I would be playing at the level that my friend's SET did not clip at and most of the SS amps would sound somewhat constrained at that volume level...and since that is subjective....
2) A scope on the speaker terminals. At no time did I get a voltage at the terminals that would equal more than 50 watts into my speaker's impedance and that was pretty darned loud. (This was at a volume level somewhat louder than the SET could manage.)
3) As you say, Thresholds do not clip gracefully. I know the sound of (one hand) clipping. Although, come to think of it, the T-200 does clip rather gracefully for SS. The QSC clips even more gracefully, which would make sense for an amp designed for live performances.
Give Me Ambiguity or Give Me Something Else!
"1)I would be playing at the level that my friend's SET did not clip at and most of the SS amps would sound somewhat constrained at that volume level...and since that is subjective...."This is due more to the design of the amps and not their power output. The Art Audio will be no feedback where the others are moderate to high negative feedback designs. I have found that especially with panel speakers, which are well damped to begin with, high damping amps (meaning those with negative feedback) will make the sound overdamped and boring or constrained.
I am surprised that you can even make the QSC clip on this speaker without damaging the speaker. It must be clipping well short of 900 watts.
in short bursts. I did manage to clip the QSC on some rock music (no really deep bass that would bottom the panel). It was insanely loud.At the merely sane loud, the amps minus 10db light seldom, if ever, blinks.
I beg to differ on one item; the panels always sound better on amps with great bass damping and control. Thats when they come alive, at least on the bass. This is the first SS amp that brings the entire range alive though.
Give Me Ambiguity or Give Me Something Else!
Power is addictive. I'd like to have about 800 watts with my stats.rw
So while I see where you are coming from as to clipping, your example lends no weight to the discussion. rp1 is best placed to answer your specific query as to how he determined that the other amps were working within their power bandwidth. At any rate, the power rating of the QSC which by no means the powerful model in that series rules out a sizable percentage of audiophile amplifiers, more so for tube amplifiers where a 900wpc amplifier is a behemoth, however it is a very modest rating for a PA amp.
Music making the painting, recording it the photograph
they didnt even bother to put a class H power supply in it. Near as I can tell from the specs, the power supply on this model is set to one rail voltage. The bigger models switch voltage rails as power needs go up.It is also the low current model, designed to only drive max continuous power into 4 ohms. The 1802 can drive into a continuous 2 ohm or less load. Aside from old Apogee's I cant think of a home speaker that needs that.
Give Me Ambiguity or Give Me Something Else!
That's for chiming in rp1, I always look forward to your posts as well as Bold Eagle's, I was beginning to despair that you had left to our little squabbles.
Music making the painting, recording it the photograph
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Give Me Ambiguity or Give Me Something Else!
*
Music making the painting, recording it the photograph
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