Well, all graphs aside, the little A07 I think is a decent $80 amp, sounds good with all the speakers I've thrown at it, all types of music. I feel like this thread is portraying cheaper Class D amps like they are all "secret stealth speaker destroyers lurking in the shadows...!"You know the Monkees song I'm a Believer, right?
My motto is: Oversimplification leads to false conclusion.
Another one: For every complex problem there is an answer that is clear, simple, and wrong.
It is more like some of these amps may self destruct with some speakers. I am grateful for @pma and his work and his perspectives which adds some diversity of opinion to the site and makes for some interesting debateWell, all graphs aside, the little A07 I think is a decent $80 amp, sounds good with all the speakers I've thrown at it, all types of music. I feel like this thread is portraying cheaper Class D amps like they are all "secret stealth speaker destroyers lurking in the shadows...!"
That has nothing to do with the frequency response measurement and claim of destructive resonance at nearly 50 kHz. You want to stick to distortion argument, do. But don't try to drag in other unrelated limitations which don't exist in real application of the amplifier.I have expected exactly this kind of reasoning. Unfortunately, it is not that simple. Even amplifier's self-distortion components are able to initiate the erratic instable behaviour and it is enough to have frequencies >=5kHz approx.
Ok, now logarithmically decay the input signal vs frequency to simulate real music spectrum and you see that is a non-issue as well.Below the example of A07 erratic behaviour into complex dummy load, and this load (post #1) is a very good approximation of a real single speaker.
Nothing remotely like that has been shown. He continues to create corner cases to complain about. As I said above, if you want the ultimate in amplification, it exists but will cost you money. The value of the Aiyama is that it is able to give you so much for so little space, money and energy use. The IC uses has very robust protection circuits and can stand punishing loads as well. Or else the one that PMA owns would have died already.It is more like some of these amps may self destruct with some speakers.
So does overcomplication to the point where you lose the plot. I already test amplifiers way past the point of how people use these devices. I run harmonic tests with bandwidth of 45 kHz for example whereas no one can hear such. I push amps to full power at 15 kHz which never, ever happens in real life (if it did, you would go deaf instantly). To keep piling on tests simply serves to confuse people about what the story of an amplifier really is. Yes, it warms the cockles of old timers who want to cling on to class AB amps that they can design and understand. But in reality it doesn't advance the understanding of the musical fidelity of an amplifier.My motto is: Oversimplification leads to false conclusion.
I think speakers need much better measurements much more desperately than amps. Maybe amp specs can use one of two additional parameters, maybe not. Speakers specs on the other hand are useless.we need much better measurement methods to be able to accurately be able to predict the suitability of an amp for a specific set of speakers and/or vice versa.
Bruno raises an interesting point - quite a lot of HiRez Flacs are actually just DSD ports which included the ultrasonic noise. They shouldn't be like this, but they are. I've got about three of them. These sorts of files played into difficult speaker loads could viably cause some of the instability discussed here.
To get that resonance you need source content that had sample rate of 96 kHz to have bandwidth of nearly 50 khz.
Ultimately this is an $80 amp with some load dependency. This is known and repeatedly stated in my reviews. You are only confusing the issue with these misleading tests.
Maybe, just maybe, those SMSLs and Toppings are real amps that give their owners just as much pleasure as your “real” amps give you, since they perform very well within the parameters the owners need them to? I don’t need to own the best in any category. I actually get a ton of pleasure from getting the device that meets my desired parameters for as little money as possible. You might as well. But you seem to argue that your parameters should be everyone’s. The question isn’t whether these are good or bad amps. It is simply to characterize them to an extent that people can decide if they meet their use case.It just goes to prove again that "high res" and DSD brought more trouble to the table than good old brick-walled PCM.
Even some high powered, very fast amplifiers in the early 1980s came with switchable (or extra) inputs for HF filtering, in order to reduce any chance of sampling frequency (44.1) issues as the CD was still a year or two off and the effectiveness of the LPFs was unknown at the time. Denon is one. Their power amps had FRs (-3dB) out to 300kHz without the filter. Two sets of inputs, one rolling off to be several dB down at 40kHz, the other wide open.
The little Aiyima amp is ridiculously good value for what it is. But it doesn't deserve being put on a performance pedestal either. It's a cute little garage amp for playing on a pair of old rat speakers while you work on the lawnmower or change the oil in your car. Maybe as a teen's 'my first college room system' it's ok- just.
I've had a few SMSL small amps and a Topping or two. They are fun for about 5 minutes. Then I give them to my Dad to play with. He gives them a workout and gives them back. Then they are either given away or in the cupboard someplace. None come close to a real amplifier in performance, usability, quality or enjoyment.
Given your tagline in your signature, it might be nice to state the voltage level these were done at. Maybe also explicitly state the bandwidth since that seems particularly relevant.