[Poll] What is your experience with the reliability of the Topping LA90D?

[SashaR]

None.
Hard to find two more identical amps, Topping churns out this stuff one after another. They are technically identical until they break. And to be clear, a defective LA90D will sound odd, reliability is a really big deal.

Yes, I read the opinion of AmirM that the increase of 2 and 3 harmonics in the LA90D is insignificant (although it is 3 dB!) - but I am attracted by his indication that there is NO dependence of the distortion level on frequency in the LA90D - and at the same time the distortion level is lower than that of the LA90! And although I have heard that this improvement is inaudible, I am very impressed with this improvement - although I do not know if it is not equalized by the distortion in 2 and 3 harmonics, increased in the LA90D ?!

 

[dan_uk]

Excuse me for the repeating my question. Can you help me with your answer?
(Besides more power, is there any reason to replace the LA90 with the LA90D?)

I "I have TOPPING's DAC and Amp (D90SE & LA90). I have not an issues for about 14 - 18 months. (I listen at 65-70 dB in stereo configuration with 6 and 4 ohm speakers)"

Excuse me for the repeating my question. Can you help me with your answer?
(Besides more power, is there any reason to replace the LA90 with the LA90D?)

I wasn't commenting on the question, more the fact you made the same statement twice in 2 different posts "I have TOPPING's DAC and Amp (D90SE & LA90). I have not an issues for about 14 - 18 months. (I listen at 65-70 dB in stereo configuration with 6 and 4 ohm speakers)"

 

[SashaR]

None.
Hard to find two more identical amps,

to be clear, a defective LA90D will sound odd,

Could you (or anyone) answer this question? Thank you!

 

[dan_uk]

Could you (or anyone) answer this question? Thank you!

My defective LA90D start to make static-like noises, random unpleasant spikes in the sound, the kind of sound that may damage your speakers.

 

[MAB]

Could you (or anyone) answer this question? Thank you!

Hard to find two more identical amps. Unless one is broken.

 

[SashaR]

Hard to find two more identical amps. Unless one is broken.

Are you talking about their identity based on published measurements or on personal, direct perception? I asked about what is the effect of increasing noise and harmonic distortion and, on the other hand, decreasing distortion - both made in LA90-D? What is the result of these changes from a theoretical / scientific point of view and, on the other hand, how is it actually perceived by those who listened to both of these amplifiers?

 

[MAB]

Are you talking about their identity based on published measurements or on personal, direct perception? I asked about what is the effect of increasing noise and harmonic distortion and, on the other hand, decreasing distortion - both made in LA90-D? What is the result of these changes from a theoretical / scientific point of view and, on the other hand, how is it actually perceived by those who listened to both of these amplifiers?

So so far below human perception.
Go to Klippel and take the the distortion perception test, see for yourself what the audible threshold is for distortion. And avail yourself of other tools to answer your questions about human audibility of distortion. At that point you might realize that these extremely low noise and distortion amps are about as closely matched as can be, differ by distortion SPL equal to about 1 gnat burp. Modern audio analyzers can measure down to that level.

 

[SashaR]

So so far below human perception.
Go to Klippel and take the the distortion perception test, see for yourself what the audible threshold is for distortion. And avail yourself of other tools to answer your questions about human audibility of distortion. At that point you might realize that these extremely low noise and distortion amps are about as closely matched as can be, differ by distortion SPL equal to about 1 gnat burp. Modern audio analyzers can measure down to that level.

Yes, yes, I am aware that analyzers hear better than people. Thank you. But I am also (primarily) interested in the theoretical / “mathematical” answer: how do the distortions at high frequencies of the LA90-D differ from the distortions produced at the same frequencies by the LA90? Does the reduction in distortion achieved in the LA90-D (they DO NOT GROW with increasing frequency) compensate for the increase in SINAD and harmonics (compared to the LA90). I understand about the gnat, but what will audio analyzers say about the DIFFERENCE in the total amount (%?) of distortion and noise in these amplifiers? I was unable to find out the answer to this question from the AMIRM charts. Can anyone answer this?

 

[MAB]

Yes, yes, I am aware that analyzers hear better than people. Thank you. But I am also (primarily) interested in the theoretical / “mathematical” answer: how do the distortions at high frequencies of the LA90-D differ from the distortions produced at the same frequencies by the LA90? Does the reduction in distortion achieved in the LA90-D (they DO NOT GROW with increasing frequency) compensate for the increase in SINAD and harmonics (compared to the LA90). I understand about the gnat, but what will audio analyzers say about the DIFFERENCE in the total amount (%?) of distortion and noise in these amplifiers? I was unable to find out the answer to this question from the AMIRM charts. Can anyone answer this?

I sent you a link to a plug-in that you can test out various distortion component mixes. Problem is, the differences you ask about are way below the typical distortion of a good loudspeaker. The only area I think an amp like this will provide an audible difference is a high efficiency driver, due to the low noise. I noticed the low noise on the Topping amp I bought with a compression driver, but it broke after a week. The good news is there are other low noise amps.

Your question might be better on the LA90 review thread, this is the broken amp thread.