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The closest approach: what amplification?

Ken Kessler titled his book on Quad "The closest approach" to summarize Quad's philosophy of producing a speaker that gets as close as possible to the reproduction of a live event. I have been wondering if there is a type of amplification that gets us closer to the real thing more than other types. I have met many audiophiles over the past few years, and what strikes me is how religious people can get about radically different types of amplification: some swear that there is nothing like small-power SET coupled with efficient speakers. Others believe that you don't have a serious system unless you use muscular SS amplifiers (e.g. 300 WPC). Others believe that powerful push-pull tube configurations are the best of both worlds. Finally, there is a small community of OTL aficionados that look at the rest of the world as if they don't know what music reproduction is all about.

Of course these people value different things. Some like imaging more than other things; others value transparency; others are crazy about huge soundstages; others seek warmth etc. And it is clear that some types of amplification are better for certain things and others are better for other things.

Now, let us consider simply the reproduction of a live event (not some specific, partial dimensions). In your experience, what type of amplification got you close to the real thing? Powerful SS, SET, OTL, powerful push-pull?
ggavetti
unsound
7,343 posts
 
I hope the OP will forgive for going a bit off topic.
Duke, with re: to "...the answer is to design speakers with as smooth an impedance curve as is practical." Would that be easier to do by lowering the impedance or by increasing the impedance?
ggavetti OP
143 posts
 
Samujohn, I misinterpreted your original post. Excellent points...thanks for clarifying.
audiokinesis
2,755 posts
 
Unsound, an across-the-board raising of the impedance curve (a la Speltz autoformer) will usually make a speaker more high-output-impedance-amp friendly, if needed. Redesigning the crossover to smooth out the impedance curve is seldom practical, but in some cases the addition of an external filter to tame an impedance peak (often present in the crossover region) can be beneficial. I would estimate that taking the impedance curve into account in the crossover design phase can more than double the workload, as the designer is trying to simultaneously optimize both impedance and frequency response, and often that which helps one hinders the other.

I like Samujohn's comment:

"I strive to recreate not the most mathematically complete model, but rather use a bit of trickery to recreate a bit of the emotional experience that draws me to music in the first place."

In my opinion the goal is to recreate the perception of the original (or fabricated) event, and focusing on perception is different from focusing on recreating the waveforms. For example, very low percentages of high, odd-order distortion are both audible and objectionable, while very high percentages of second harmonic distortion are inaudible or barely audible, and are not objectionable. I've seen data that indicates 30% second harmonic distortion is statistially inaudible, but it looks bad on paper if the yardstick we're measuring with is THD. A perception-based yardstick has been proposed, but has not found acceptance unfortunately.
samujohn's avatar
samujohn
291 posts
 
Tricks: Digital amplification is inherently capable of performing complex processing without causing additional (unintended) distortion. I can compensate for room acoustics, draw and save my own response curves, program various real time corrections for loudness contours, and more. I have no wish to be a commercial for any product, merely to illustrate that we are at the beginning of a total revolution in audio as we marry computers to amplifiers. Preamps will disappear and programmable amps will detect the input requirements (my MacIntosh does) and equalization required for the speakers. Interconnects will disappear. I can't wait!
unsound
7,343 posts
 
Duke, using an auto transformer would, at least to my sensibilities, be a bit beyond typical speaker design. In my limited experience, those speaker designers that have designed their speakers to have a smooth impedance curve such as Jim Thiel, as part of what I sususpect to be an effort to have a steady amplitude response, have adjusted their crossovers in just such a manner. It appears to me that it might be easier to adjust a speaker to have a smooth impdeance curve with a lower rather than a higher impedance curve. Then again, I really have no real personal experience or technical back round to claim this with any authority.
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