https://www.stereophile.com/content/sonic-impact-model-ta2024-super-t-power-amplifier-measurements
J.A measured the Sonic super T, of course didn't do that good.
J.A measured the Sonic super T, of course didn't do that good.
https://www.stereophile.com/content/sonic-impact-model-ta2024-super-t-power-amplifier-measurements
J.A measured the Sonic super T, of course didn't do that good.
Many years ago, magazine reviews did make an attempt at testing amps into a simulated complex load, albeit a 2uF in parallel with 8 ohms to simulate an electrostatic loudspeaker, but that doesn't seem to happen these days.
Personally, I can't see the point testing any amplifiers of the switching variety that exhibit high levels of spurious out of band signals. They do absolutely nothing to advance the pursuit of high fidelity and are a challenge to measure in any case. Special 'consideration' must be made for them in terms of filters for test gear. Hardly a level playing field.
An amplifier should be silent and not be an RF transmitter.
What impact on fidelity do you believe out of band signals have?
It's really simple. Waveform fidelity is compromised. Show me any PWM/PDM amplifier that can manage a decent 10KHz square wave, at a reasonable voltage swing. Hint: they can't.
A correctly engineered amplifier simply increases the amplitude of the waveform and adds nothing else. Residual noise should be as low as possible. Excess, non-harmonically related spuriae are also unacceptable.
If you are going wideband, there should be no spurious signals, unrelated to the input in that band. IMD products will appear in the audible bandwidth folded down from out of band HF tones (switching frequencies etc). If you are bandwidth limiting (as in the case of PWM/PDM amps), out of band spuriae are simply a byproduct of poor filter design, laziness and general cheapness.
So-called 'digital' amplifiers have infested every part of consumerdom because they are cheap and cheerful. They have improved in the last 20 years, but they are not remotely close in absolute performance, to carefully engineered analogue amplification. If you want an instrumentation-grade amplifier with a ruler flat response, vanishing levels of distortion and noise, and freedom from frequency response anomalies into varying loads, that amplifier will not be a PWM/PDM unit.
Ok, but by this standard, we can rule out literally any DS DAC or other DAC that uses an imaging filter from being good enough to be worth measuring. That would seem absurd to me.
Well no amplifier does this. The point of measurement is to determine how far an amplifier departs from this ideal.
And the measurements will show these and readers can interpret their audibility or offensiveness
IMHO unrealistically lofty standards for a thread entitled "$500 amplifiers to test and review". In this price range, I'd hazard to guess that many of the best-measuring devices would in fact be class D.
And what the hell is a "cheerful" amplifier?
Not true. Most competently designed D/As, whether they be DS or Multibit have little or no out of band spuriae of significance. The key word is significance. Amplifiers with hundreds of millivolts or RF out of band are poorly designed. Full stop.
Consider conventional distortion meters have to have outboard filters as do digital A/D based analysers as there is simply so much out of band crap to deal with. Again, simply faulty design.
No, measurements are measurements. No direct interpretation on 'offensiveness' can be drawn from measurements. They serve to analyse the objective performance and the 'offensiveness' is purely subjective and may vary from person to person- hence a completely useless metric.
I don't believe so at all. Having spent a considerable period of my life selling audio equipmnet, prior to the widespread adoption of PWM/PDM amplifiers, and the rest of my life repairing, testing, restoring, and rebuilding gear, I'd hazard a guess completely opposite. I've had many ClassT/PDM/PWM 'digital' amplifiers either across my bench or to play with, and they are all ultimately flawed in one way or another. Yet on the other hand, I have literally hundreds of amplifiers (yes) that are essentially without flaws and they are all solid state Class AB amplifiers.
Cheap and cheerful. It is an English saying. Basically means inexpensive and fun to play with but shouldn't be taken seriously or considered state of the art in any way.
Music is a collection of waveforms. Nothing more and nothing less.
Well, I willl certainly have to disagree with you on that - music can be a subjective source of great human pleasure - if you look beyond the physics of it.
That works, but even better, music recordings are collections of waveforms.What if it were rephrased to: "Recorded music is a collection of waveforms. Nothing more and nothing less"?
I am interested in Class D because of their substantial efficiency (85% is not uncommon). Wasting watt is not an option for me since I am essentially Off grid, Solar with back-up generator. Moreover it seems that building an amp these days can be as simple as a case, a Power supply (SMPS likely) and ICEPower, Hypex or Ncore amplifier modules...