Topping LA90 Review (Integrated Amplifier)

[McFly]

I'm by no means an amplifier designer but I've measured a few and repaired a couple. I suspect the key here could be the power supply. AHB2? SMPS. This amp? External DC SMPS. Everything else with "ugly" noise floors? Internal wire wound transformers and bridge rectifiers aka linear power supplies.

Yes, credit to those who have, you can make ultra quiet amps with big iron supplies but it seems to me it might just be easier to get the power supply that's spraying magnetic fields all over the place away from the audio circuits or use one that doesn't.

 

[Doodski]

It seems a bit over priced for the amazon.ca price of CDN $1169.00 It's nice that the SINAD has been improved beyond doubt although the price is stifling. The pricing is a bit optimistic.

 

[aravena562]

I think that for a traditional old school audiophile who hates class d, two monoblocks in class ab can be a good alternative, in the end for 1600 dollars you will get the cleanest 100 watts in 8 ohms that exist. let's compare that with amps that measure poorly and are worth 5 times that value. Seen that way, it doesn't look bad. What worries me the most is its ability in monoblock mode to handle lower impedance in the speakers.

 

[TheBatsEar]

It seems a bit over priced for the amazon.ca price of CDN $1169.00 It's nice that the SINAD has been improved beyond doubt although the price is stifling. The pricing is a bit optimistic.

The price imported from Audiophonics might be interesting.

• 899,00€ with tax
• 749,17€ (CDN $1.022,69, US $802,51) without tax

Then again, you probably have to pay some form of tax as well, also shipping.

 

[TheBatsEar]

What worries me the most is its ability in monoblock mode to handle lower impedance in the speakers.

It's achilles heel indeed.

 

[Doodski]

@amirm is it possible you can combine a teardown with a video review?

 

[Red@]

Hello,
Any idea on the input impedance ?

 

[pjug]

This (above) combined with the power supply that appears to be single rail (64V@4A), suggests the amplifier is already running in bridge mode when operated in stereo.

Switching to mono creates a bridged, bridge amplifier. It is highly likely this amplifier will have trouble with impedances below 4R in mono. Their spec also says 8R is the minimum in mono mode.

[sorry, I deleted earlier reply that did not make much sense]

But the numbers (output power with 64V supply) don't compute for it to already to be bridged in stereo, do they?

 

[TheBatsEar]

Hello,
Any idea on the input impedance ?

I think it was answered in this thread somewhere:

https://www.audiosciencereview.com/...opping-la90-review-integrated-amplifier.33362

 

[restorer-john]

It isn't bridged, is it? Just offset by half the rail is what I was thinking it might be. So just steady 32V DC on speaker neg and about waveform+32V on the + speaker connection. If so is that unusual? I haven't heard of such a design but I'm guessing I just am not aware of some that do exist.

A floating speaker negative sitting at 32V with respect to Gnd is not likely, or safe.

I figure the power adaptor markings might just be wrong and it is a 32-0-32V supply, not a single ended 64V supply. Then all the figures would line up.

But until we see an internal shot, it's just guesswork.

 

[restorer-john]

[sorry, I deleted earlier reply that did not make much sense]

But the numbers (output power with 64V supply) don't compute for it to already to be bridged in stereo, do they?

No. (see above)

 

[Doodski]

But until we see an internal shot, it's just guesswork.

Teardown! teardown! teardown!

 

[Red@]

I think it was answered in this thread somewhere:

https://www.audiosciencereview.com/...opping-la90-review-integrated-amplifier.33362

No, it is not mention, a went through all the posts.
Anybody has an idea guys ?
(topping are know for having unusual input impedance in their Amps)

@amirm would you say the performance stays the same with a 60ohm (83 dB per 1mW sensitivity) headphones ? (As opposed to the 4R and 8R measured loads)

 

[JohnYang1997]

Thank you @amirm for the review. Only one small thing, the crosstalk should be at around -140db at 1khz.

 

[AdamG]

Notice: Because of my less than Brilliant move today with merging multiple threads. The Original Poll data was lost. Please do vote again if you are so inclined. I personally would be very pleased if you do. Thank you kindly.

 

[mdsimon2]

@JohnYang1997 what is the input impedance?

Michael

 

[TheBatsEar]

No, it is not mention, a went through all the posts.

Sorry, might have been lost in the hectic of the shuffling of the threads.

 

[TheBatsEar]

Thank you @amirm for the review. Only one small thing, the crosstalk should be at around -140db at 1khz.

Congratulations, what a nifty little amp with impressive measurements.

 

[staticV3]

Only one small thing, the crosstalk should be at around -140db at 1khz.

And indeed, WolfX-700 measured <-140dB crosstalk @1KHz on the same AP analyzer.


Hmm

 

[VintageFlanker]

Congrats @JohnYang1997 for this engineering accomplishment.

Now, from a consumer point of view, this product doesn't make that much sense at its price. A 120dB SINAD amp is meaningless when it comes to audibility and usability. I would have preferred a 100dB one with fourth time the power, really.