Shorting the output is also an abnormal event. Should we therefore not concern ourselves how an amplifier behaves when this happens?
Clipping recovery tells a lot about the effort that has gone into it by the designer - and it’s important that it behaves well as it recovers.
We make the post human revolution.
AI will discuss all - we will be demobilized for this forum.
Too dumb to be kept in play.
Please do not bring ASR here. They believe THD is all there is. No need to listen.
Frequency response to bench test resistor or real speaker? I think there is difference. Especially with certain class of amplifiers with low damping or current source.
Every time i swap amp or preamp, i do eq flat in listening position. That way i eliminate this, and of course correct the room modes.
I am listening to the 'tone' of amplifier. Not frequency response deviations.
Very valiant effort Bonsai, but in the end futile, i am affraid. We will agree to disagree, since everyone has different taste. Just like we each like different cars, vine, or movies, we all look for different sound to please us.
Like bimo or tillerson said, i like to put shades on mona lisa, whatever that means.
I heared quite a number of amplifiers with very low distortion which sounded like crap. Dry, emotionless, fatiguing. THD is irrelevant for me.
I look for lush yet clean sound, which gives chills to my spine when i listen. Certian opera arias brings tears to the eyes and pressure in the chest. If that amp measures bad, who cares. So certain amount of right harmonics it is. Its not easy to achieve, but it happens.
I ignore double blind bs crap. Please spare me of that.
One more thing, there is claim here, that below certain level THD, we do not hear distortion. But i compared dozen opamps in dac, all very low THD, and i could hear differences. Why? Yes, it was not double blind bs. There is more to sound than THD.
It’s not about deciding if an amp is low distortion or not. If you look at what’s being proposed, an amp with 0.5 % distortion can still score quite highly, but an amp featuring 0.0001% (ie 1 ppm) that fails where it counts on other areas wing score as well. It’s about getting balance into amplifier ratings and making sure at the very least, they are well designed and engineered.
I don’t give anyone a hard time for building a 0.5% distortion amp. What I do object to is when either camp claims they have it right and the other is wrong.
🙂
I don’t give anyone a hard time for building a 0.5% distortion amp. What I do object to is when either camp claims they have it right and the other is wrong.
🙂
Ok.
Just one last thing. What about amplifier-speaker interface. Not all combinations work. Certain amplifier can be pronounced unlistenable with wrong speaker, yet can sing like angels in heaven with right one.
How do you score for that?
Just one last thing. What about amplifier-speaker interface. Not all combinations work. Certain amplifier can be pronounced unlistenable with wrong speaker, yet can sing like angels in heaven with right one.
How do you score for that?
Ok, the very last thing, i promise. After this i go away putting shades on mona lisa.
What about bi-amplification. In three systems i use, i have active crossover to split signal (150Hz) for woofers and the top mid/tweeter section. Woofers are powered by either plate amps or any 60+ watts classAB i have. Top from 150Hz is powered by small power classA amps, which i rotate occasionaly.
Small classA would likely fail powering big tower power hungry speakers. But it fits perfectly for bi-amp system.
How do you score for that?
What about bi-amplification. In three systems i use, i have active crossover to split signal (150Hz) for woofers and the top mid/tweeter section. Woofers are powered by either plate amps or any 60+ watts classAB i have. Top from 150Hz is powered by small power classA amps, which i rotate occasionaly.
Small classA would likely fail powering big tower power hungry speakers. But it fits perfectly for bi-amp system.
How do you score for that?
It seems like you forgot the one thing that actually matters: frequency response (see post #33, https://www.diyaudio.com/community/...overall-amplifier-quality.407222/post-7552542 ). Then again, it's only an example.
You already gave the answer, didn't you? You are probably fooling yourself with your uncontrolled tests.
Then again, it could also be due to intermodulation between all the ultrasonic rubbish coming out of a DAC chip, rubbish that will normally be filtered off before the signal reaches the main amp.
That's the whole point of this thread.
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No, I just didn't worry about including it after I'd noticed the omission.
I haven't seen you recommend to remove the remaining factors... 😉
Now you're getting it... But, since it seemed to trouble you enough to type a response... Here ya go. Hope it serves as a better example of the chart type. 🙂
You think right, I measure into resistors, R//C, simulated speaker load and also with real speaker. I also measure an effect of speaker cable to frequency response. It is all about amplifier output complex impedance and amplifier stability. Nothing new here. Speaker cable adds more deviation than the amp with low Zout. Forgive me being brief, I am adding some plots instead.
Measurements:
Simulation (different speaker)
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Without equalization, current drive is not suitable for loudspeakers designed for voltage drive, but nowadays there are many people here using fancy room equalization tools that could probably correct for the bumps in the response that you get with current drive. Electrodynamic loudspeakers usually distort less with current than with voltage drive. In fact, when driven with voltage at frequencies where the voice coil dominates the impedance (anywhere except near resonance), the voltage gets converted into a current by the nonlinear voice coil impedance and that distorted and compressed current then drives the loudspeaker. (Then again, if you want low distortion, you are probably better off with an electrostatic loudspeaker, the step-up transformer of which needs to be driven from a low impedance for minimum distortion.)
Back on topic: for current output amplifiers, I think test 8 should measure the response of the amplifier output current with an emulated loudspeaker load. It may be less relevant, because you will need equalization anyway.
Exactly, everyone should understand this. And the equalization is not simple and the result may be tricky, for many reasons.
If you were that misinformed that you used it to try to drive big power hungry speakers then it’s hardly the amps fault that you have mismatched it to the load is it?
Most people using small amps pair them with efficient speakers.
As far as scoring goes, you look at the amps specs and measure against that ie it is treated like a black box within the constraints of its spec.
I'm going off topic for a bit.
I believe that when the cone vibrates nonlinearly due to physical factors (for example, when it collapses at the tip of the vibration), the back electromotive force of the voice coil also becomes nonlinear (the back electromotive force decreases), and the flowing current becomes nonlinear (increasing current). I have the impression that this will reduce distortion.
In other words, the core magnetic distortion of the transformer is reduced when driven at low impedance. (I think there was a patent for driving with negative impedance that cancels the winding resistance.) I have a similar image to that, but am I wrong?
Is that so?
I believe that when the cone vibrates nonlinearly due to physical factors (for example, when it collapses at the tip of the vibration), the back electromotive force of the voice coil also becomes nonlinear (the back electromotive force decreases), and the flowing current becomes nonlinear (increasing current). I have the impression that this will reduce distortion.
In other words, the core magnetic distortion of the transformer is reduced when driven at low impedance. (I think there was a patent for driving with negative impedance that cancels the winding resistance.) I have a similar image to that, but am I wrong?
I wish I'd spotted this thread earlier. While I've been guilty of chasing 1ppm 20kHz full power, eg my ravings on ASTX's amp thread, if I was to go back to commercial amp design, my main SQ criteria would be based on some 2 decades of DBLTs .. though only a few intense periods of these were on amps.
On the AC coupling issue, I've ooh'd & ahh'd over this in the past and my present inkling (supported by a few DBLTs) is to limit LF quite severely to have quick recovery. While I don't like my amps to 'block' for usecs as in your test 10, da DBLTs show this is actually innocuous 😱 .. while the msec or greater 'blocking' from assymmetrical overload is certainly audible and alleviated by LF cut. loads of caveats about this including senile memories from a beach bum 🙂
I'll try and post more stuff when I can drag myself from beach bum activities