Topping LA90 Discrete Amplifier Review

[mike7877]

L7Audiolab measured the volume knob's impact on the original LA90 at 5W/4Ω:
View attachment 365547 View attachment 365548
Source: https://www.l7audiolab.com/f/topping-la90/

Roughly the same impact can be expected with the LA90D.

Nice.

Check this out:

50mV -83dB THD+n

SNR has to be higher than THD+n. In this case I don't know by how much, but for fun let's say the noise is at -87dB compared to signal - puts it pretty high up there in the ASR chart of headphone amps (best being 95 except for the L30 II)... We already know the thing sounds good- at this point, might as well make a 2x speaker wire (terminated with banana plugs) to female 4 pin XLR connector and use the LA90(D) as a headphone amp! Comes complete with volume control lol

 

[Michal]

Does this amplifier have any operational amplifier in the signal path, or maybe it is a 100% discrete circuit from input to output?

 

[babadono]

Does this amplifier have any operational amplifier in the signal path, or maybe it is a 100% discrete circuit from input to output?

I would assume yes...but I sure want to take one apart. Don't think we will ever know what is in the black encased modules. Just received a 9" 2mm T handle hex key for this very purpose.

 

[Michal]

I would assume yes...but I sure want to take one apart. Don't think we will ever know what is in the black encased modules. Just received a 9" 2mm T handle hex key for this very purpose.

Hi
Are you ready to say something about the construction of this amplifier?

 

[babadono]

what the? replied twice from my phone and it ain't here? sometimes this stuff baffles me...anyway no I have not taken either of my amps apart. Too busy enjoying listening to them.

 

[LucreciaBorgia]

Yes.

LA90 Discrete Power Amplifier-TOPPING

View attachment 358576

Does somebody knows the Imput impedance of the LA90D ? Strange that is nowhere to be found, it is an important criteria....

 

[staticV3]

Does somebody knows the Imput impedance of the LA90D ? Strange that is nowhere to be found, it is an important criteria....

The LA90 had 20kΩ Zi, the LA90D is probably similar.

 

[LucreciaBorgia]

Not so good...I was expecting at least 40/50 KOhms....

 

[LucreciaBorgia]

Is there a fuse in the device (or in the power supply) ? I can't see any ...

 

[babadono]

The LA90 had 20kΩ Zi, the LA90D is probably similar.

That would be balanced I think. I believe I saw John chime in somewhere that that is what he recalled but he was not 100% sure. If putting some kind of adapter or unbalanced cable it would probably be half that so 10K?