Topping LA90 Review (Integrated Amplifier)

[restorer-john]

For some reason, power cycling is when most of these devices fail.

Very common.

SMPS supplies contain capacitors which, as they age, their capacitance decreases and the ESR (effective series resistance) increases.

The crazy thing is, if you keep a failing capacitor warm, its ESR actually stays low (decreases) up to a point. As soon as you turn off the supply and it cools, the ESR skyrockets, the capacitance is low and the SMPS wont function well enough to supply the downstream circuitry. Often so much instability the unit fails to startup or even function at all.

 

[theREALdotnet]

The crazy thing is, if you keep a failing capacitor warm, its ESR actually stays low (decreases) up to a point.

I did not know that. I thought it had to do with thermal cycling (of solder joints and such). Neither of it seems to apply to the Topping D90 – it has a linear power supply as far as I can tell, and doesn’t really get warm. It’s a low power device after all. Which is why there is not much sense in fretting over power consumption when leaving it on 24x7.

 

[MyCuriosity]

Certainly not if you bought one based on the ASR rating.

The reviews are just a point in time measurement or group of measurements. It takes time, expertise, experience and insight to predict failures. There’s plenty of cheap HiFi being peddled as something special, and I and plenty of others would not touch it with a 10ft barge pole.

Some of our predictions have already proved to be eerily accurate. And we have no dog in the fights.

You decide. Cheers.

I agree and I am not challenging the accuracy of the measurements.

 

[restorer-john]

I did not know that. I thought it had to do with thermal cycling (of solder joints and such).

I first discovered it for myself years ago. I in-circuit measured ESR of failing SMPS supply's caps and they showed a high ESR. So, I duly desoldered them, and tested out of circuit, only to see the ESR low (almost normal). It dawned on me that the internal heating kept them working (just) until they got turned off and cooled. Just the effect of desoldering the cap, heated it enough to show an almost normal ESR. That was until they came down to room temp and the ESR was high again.

It's the reason an LED light will work perfectly when left on 24/7 and then when you turn it off (and it cools), it will fail to turn back on.

I'm pretty sure it's common knowledge among technicians now, but back in the day when ESR meters were rare, I reckon many pieces of gear went to landfill due to the inability to find the problem.

 

[snakeoilsalesman]

Very common.

SMPS supplies contain capacitors which, as they age, their capacitance decreases and the ESR (effective series resistance) increases.

The crazy thing is, if you keep a failing capacitor warm, its ESR actually stays low (decreases) up to a point. As soon as you turn off the supply and it cools, the ESR skyrockets, the capacitance is low and the SMPS wont function well enough to supply the downstream circuitry. Often so much instability the unit fails to startup or even function at all.

My subs actually state this in the manual, and therefore suggest leaving them on 24/7.

 

[theREALdotnet]

My subs actually state this in the manual, and therefore suggest leaving them on 24/7.

Interesting, what subs are these? Usually, manufacturers stop short of recommending something like this, lest they be labelled environmental vandals.

 

[snakeoilsalesman]

REL’s. The wording they use is pretty layman, calling it “strain on electronics” or something like that, but yeah.

 

[WeBuild4Life]

Just popping in this thread to see if there is any reason not to buy this amp.

I am building the Eslinore Towers and they are VERY efficient - 92db or so almost the full range. They do have high peak RMS at around 350watts, but I can't imagine I ever use that much.

I am between MONOing the LA90 or MONOing the Vidar 2 from Schiit. More power with the Schiit, bigger unit.

@amirm has anyone offered the Vidar 2 to you yet? My Budget is around $1500 with a stretch to 2,000.

I looked through the entire review archive, and the Vidar 2 seems like such a great value and does have good "independent" measurements.

This LA90 is promising, especially after me LOVING the A90/D90 stack I bought.

Can you offer advice on what you would do? Any alternative option in this price range that can push 300watts, whether single unit or dual mono units?

Thanks!

 

[staticV3]

@webuildforlife in Mono and with the LA90 in High gain, the Vidar 2 has 3x as much noise/hiss as the Topping.
And if you can utilize the LA90's Low gain, then the Vidar 2 has more than 4x as much noise.
In turn, the Vidar 2 gets about 30% louder.

 

[WeBuild4Life]

@webuildforlife in Mono and with the LA90 in High gain, the Vidar 2 has 3x as much noise/hiss as the Topping.
And if you can utilize the LA90's Low gain, then the Vidar 2 has more than 4x as much noise.
In turn, the Vidar 2 gets about 30% louder.

In mono, are you saying the Vidar 2 has a bit less noise comparatively then when driven in stereo? I forgot about the hiss - how do you check that when looking at statistics?

I don't think Amirim has measured the 2, but the 1 got good marks and the 2 is just "better" overall I think.

Measurements aside. I would be running the stereo amp off the A90d pre-amp which is fed by the D90le, so it may be tooo analytical? Not sure. I am not a critical listener for stereo. headphones, yes. (though I am critical about how both sound)

 

[staticV3]

In mono, are you saying the Vidar 2 has a bit less noise comparatively then when driven in stereo?

No. Since you said you were considering Mono Vidar 2 vs Mono LA90, my numbers are just that. Mono vs Mono.

I forgot about the hiss - how do you check that when looking at statistics?

Topping state absolute noise directly in their specs. For the Vidar 2 I had to convert their relative noise numbers (SNR) to absolute using the generator level stated in the APx555 report and the gain of the Amp (simple math).
Luckily, both Schiit and Topping use A-wt, so their numbers should be fairly comparable.

 

[WeBuild4Life]

No. Since you said you were considering Mono Vidar 2 vs Mono LA90, my numbers are just that. Mono vs Mono.


Topping state absolute noise directly in their specs. For the Vidar 2 I had to convert their relative noise numbers (SNR) to absolute using the generator level stated in the APx555 report and the gain of the Amp (simple math).
Luckily, both Schiit and Topping use A-wt, so their numbers should be fairly comparable.

When we are talking hiss though, is this audible beyond 3feet? I know my QSC amp has hiss at a few feet, but I listen to that several feet away and hear nothing.

Other than that, overall quality should be okay on both? I think LA90 is great if I didn't need the extra power overhead.. Tough choices though. Would love to see how the vidar 2 measures though.

 

[staticV3]

Would love to see how the vidar 2 measures though.

There's a full APx555 measurement report on Schiit's website: https://www.schiit.com/products/vidar2
Just go to the Specs tab, then scroll all the way down.

It's not particularly pretty. The Vidar 2 leaks quite a bit of power supply noise into the output.
2V at 8Ω Mono shows 86dB SINAD on the Vidar 2 vs 115dB on the LA90 under the same configuration.
What's more, about 87dB SINAD is as good as the Vidar 2 can get at 8Ω Mono. It just plateaus there until it clips, from 1W all the way to 300W.

 

[WeBuild4Life]

There's a full APx555 measurement report on Schiit's website: https://www.schiit.com/products/vidar2
Just go to the Specs tab, then scroll all the way down.

It's not particularly pretty. The Vidar 2 leaks quite a bit of power supply noise into the output.
2V at 8Ω Mono shows 86dB SINAD on the Vidar 2 vs 115dB on the LA90 under the same configuration.
What's more, about 87dB SINAD is as good as the Vidar 2 can get at 8Ω Mono. It just plateaus there until it clips, from 1W all the way to 300W.

Truthfully, I am learning how to read those reports so I didn't fully get it.

I wonder if some Nord Acoustic amps may be a better fit. Just trying to find that 300-400w per channel sweet spot. Thanks!

 

[staticV3]

I wonder if some Nord Acoustic amps may be a better fit. Just trying to find that 300-400w per channel sweet spot. Thanks!

Are you aware that 300-400W into the Elsinore would drive the speaker to almost 120dB SPL Peak?

 

[WeBuild4Life]

Are you aware that 300-400W into the Elsinore would drive the speaker to almost 120dB SPL Peak?

Yes! I am trying to keep the overhead needed. I do believe you need a lot of power for headroom for transients in music. I don't plan to play them that loud.

Edit: that reads weird. Basically even if I am playing 90db at 1watt, I still want 6 octaves of head room, which is still only 64watts and there is this current thing I am learning about which means you need even more than that for certain music. Maybe I am going down the wrong path.

I think I am going to make a separate post.

 

[Shadders]

Hi,
I did a quick check on the LM3886, and it has an open loop gain of 115dB (typical). For the low gain mode of 9.5dB for the peak output, then that infers 105.5dB of feedback. That is quite a lot of feedback.
Regards,
Shadders.

 

[knobtwiddler]

More good stuff portending the rise of Topping in the amplifier world! Enough going on to turn my head from Benchmark as power rises and the designs mature. Topping has proven that it's not only Benchmark/THX that have magic AB sauce!

Indeed. Were I an IP lawyer for THX, I'd scrutinise the Topping just to be sure they aren't using the very same sauce!

 

[restorer-john]

Indeed. Were I an IP lawyer for THX, I'd scrutinise the Topping just to be sure they aren't using the very same sauce!

Or that THX had simply taken other ideas, from equally skilled designers and somehow managed to use smoke and a few strategically placed mirrors to get a 'US patent'...

 

[knobtwiddler]

Peter Walker?

Indeed. The audio world of full of questionable patents. However, we are where we are. It's been suggested that the patent takes off where Quad's [expired] one left off. I haven't studied it enough to confirm this, I'm just interested to know if Topping could release a Class A/B amp with those specs without utilising some form of FF error correction. And if they did, would it be of interest to THX's lawyers? (not suggesting it would be morally right for them to pursue Topping over it - although they would likely feel duty bound)