Topping LA90 Discrete Amplifier Review

[babadono]

IDK...I have 2.4 and 5G wireless in the home. We are in So Cal but in what some would call semi rural. But So Cal. nonetheless. Pretty sure the air is full of waves
Have you verified how your cables are wired? Just for a test short the shield to the center pin on the RCA end of the open cable. Does noise go away?

 

[dcolak]

Moved to another room, no noise. It was RF, not sure how to check cable wiring, can't disarm them. Funny how amp picked it up

 

[babadono]

That's why I love balanced connections. You can make your unbalanced outputs balanced if you know the circuitry (have schematic).
https://www.jensen-transformers.com/wp-content/uploads/2014/08/an003.pdf. See A Simple Alternative, Adding a Balanced Output.

 

[Panelhead]

I think the issue here was more the 2.00 cabling.
Either spring for some 10,000.00 cables or make your own. The connectors are the only expensive part.
I use chassis wire and the ancient Eichmann Bullet plugs for RCA. For balanced either Canare, Gotham, or Sommer.

 

[babadono]

? you are joking, right?

 

[mike7877]

I knew my message might provoke this kind of reaction, but my intention was never to discredit Topping. I am simply sharing my personal experience. Let me reiterate: I was completely satisfied with the LA90 Discrete until my room became truly quiet. I actually did contact the manufacturer, described the situation, and purchased a couple of new power supplies - which, as I mentioned above, turned out to be just as noisy. I didn't want to bother with a return because I don't own specialized measuring equipment to officially prove the noise level to the seller. If you can tell me how to do that easily at home, no problem. But honestly, I am just tired of this whole situation.

Also (even though this is slightly off-topic), since the beginning of this summer, I have encountered serious hardware failures with two consecutive D90 III Discrete DACs. A local authorized service center officially concluded that the entire early batch suffered from a manufacturing defect. I will definitely share the details about this in the appropriate thread later.

What I really meant to say is that I find it unacceptable for flagship (as you say) devices to emit such kind of mechanical noise and "beehive" effect. Please don't take this as disrespect, but your logic seemed to me even stranger - suggesting that users should build sound-absorbing boxes for their power supplies is highly amusing. I wonder if Topping is aware of this workaround? Perhaps they should start offering such boxes as an optional extra, instead of making their flagship silent out of the box.

I will repeat that I am just a regular user sharing my personal experience with other regular users. I am not promoting any other brands; I am simply stating that my issues ended after I replaced my DAC and amplifier with devices from another manufacturer. If more professional users with scientific knowledge on the matter want to correct me, I would be happy to hear from them.

A SMPS is just a controller chip, some transistors, and some passive parts (mainly caps and coils).
They are all inexpensive and reliable and operate the same way. A $500,000 piece of lab equipment is very likely to use the same chip in its power supply as one in a budget laptop's power brick...

If a SMPS design doesn't make noise, that same design with other parts (of the same model) should not make noise either - unless there is a faulty part somewhere critical (like a coil on a high current output which missed some glue). Basically they will all buzz, or only a few, at random will buzz.

Since you got two that made unacceptable level of noise, and you got two more that also gave you an unacceptable level of noise, I can only conclude that 1.) you're extremely sensitive in an extremely quiet environment, or, 2.) you're extremely, extremely unlucky.

In either of those cases, this is not an issue for most people. I bought two one year apart, and neither of the power supplies make a sound. The way that you go through four of them and they all make this noise... I find it hard to believe.


Since you asked, the reason I suggested to do something about the supposed buzz, is, high frequency sonic energy is EXTREMELY easy to dampen down to nothing - extremely. And comparable amplifiers are extremely EXTREMELY expensive... You could make a bass trap that integrates them very easily and brings down the nearly inaudible buzz down by 30dB instead of spending half a car on the next equally-capable amplifier on the market... Since you're willing to just toss these amps aside as a loss, you seem to be making this problem very large, when, at the level you're apparently trying to avoid, you're just as likely to have the replacement gear make as much (or even more), and the PSU be in an area you can't treat.
When setting up an audio room, lots of treatment is done, and a bit for a power supply is not unheard of lol


edit: I saw you suspect the quality of power provided by the utility as a potential reason for your four units making noise while others do not - this is not the case. The grid can't have high frequency noise on it because of the inductance of the wires (they're really long and solid core and go through low pass filters (ie. step down transformers). If you had something with a big SMPS locally in your home (like a high efficiency fridge or something, maybe washing machine), and it was broken, it might send its switching noise through your house, potentially causing things to buzz. This is unlikely though. You could switch every breaker off in your home except to the LA90 power supplies, and if they still buzz you rule that possibility out

 

[Le_Passager]

A SMPS is just a controller chip, some transistors, and some passive parts (mainly caps and coils).
They are all inexpensive and reliable and operate the same way. A $500,000 piece of lab equipment is very likely to use the same chip in its power supply as one in a budget laptop's power brick...

Thanks for the detailed response! I agree, the whole situation is very strange. The interesting thing is, I don’t consider myself overly sensitive to noise, nor am I an experienced audiophile - this was actually my very first setup (to be honest, I didn't even hear much of a difference in the sound between LA90 D's and new power amplifier). But this hum... However, the fact remains that the coil whine/hum from these four-in-a-row SMPS units literally forced me to replace the whole power amplifier. I feel like Chuck McGill from Better Call Saul in this situation . I might be missing something here, so I hope to figure it out eventually and will report back with an update.

I'm currently planning to acoustically treat the room using an UMIK-1 measuring microphone. I'll also try to use it to measure the noise level of these SMPS units in my room.

 

[stefanovesa]

Just sharing my two cents. My problem was the opposite of yours. There was no whistling from the Topping LA90D's switching power supply, but a few years ago, I had a CD player with a toroidal transformer (so, a linear power supply) that did whine. The whining stopped after the utility company made changes to the local distribution substation. This just goes to show how complex things can be. It seems highly unlikely that all these power supplies would have the same issue—or else you’ve been extremely unlucky.

 

[Le_Passager]

Это лишь подтверждает, насколько сложными могут быть вещи.

That's right, I completely agree.

I don't remember if I mentioned this before, but the linear power supply with a toroidal transformer in my new power amplifier isn't ideal and completely silent. But this noise can only be heard by putting your ear directly to the amplifier. In my case, this noise is perceived as much less intense than the SMPS units of LA90 D's.

So yes, everything varies, from case to case.

 

[fendy323]

hi im looking amp for drive ae300mk2,.. now already have d90+a90 OG version..
still confused to decide betweek pa7 or la90d... for pc use

 

[RichB]

I picked up an LA90 discrete as a backup amp. The AHB2 that I had bought used needed repair after showing faults on cold power up.

No A/B compare right now. The clarity is great, but the bass is lacking, I mean really lacking driving the Revel 128Bes.
It sounds like there is a HPF filter in play, practically no bass listening to Massive Attack Mezzanine.

I checked the measurements in the review and it seems like a great 1kHz amplifier.
Perhaps, power measurements at multiple frequencies would have revealed something.

- Rich

 

[staticV3]

Perhaps, power measurements at multiple frequencies would have revealed something.

You mean like this?



Yeah, they've revealed no bass issues whatsoever:

 

[RichB]

You mean like this?

View attachment 559481

Yeah, they've revealed no bass issues whatsoever:
View attachment 559482 View attachment 559483

Looks great. And yet, something is not right here.
I'll wait until the AHB2 return compare.

- Rich

 

[staticV3]

Looks great. And yet, something is not right here.
I'll wait until the AHB2 return compare.

- Rich

Make some recordings with a standmounted mic to rule out bias.

 

[dcolak]

I picked up an LA90 discrete as a backup amp. The AHB2 that I had bought used needed repair after showing faults on cold power up.

No A/B compare right now. The clarity is great, but the bass is lacking, I mean really lacking driving the Revel 128Bes.
It sounds like there is a HPF filter in play, practically no bass listening to Massive Attack Mezzanine.

I checked the measurements in the review and it seems like a great 1kHz amplifier.
Perhaps, power measurements at multiple frequencies would have revealed something.

- Rich

When I said the same thing the mob tried to lynch me.

 

[RichB]

When I said the same thing the mob tried to lynch me.

I am not surprised.
Just remember, there measurements are NOT comprehensive. Speakers are reactive loads.

I do not blame manufacturers for making certain that the measurements will look great. They should do that.

They should also design for loads that are not resistors.

The existence of reactive loads seems to escape some of the illuminati. Though it has been obvious to pretty much anyone that many amplifiers are not ruler-flat even with the Stereophile simulated speakers, often clearly exceeding audibility limits.

- Rich

 

[stefanovesa]

I picked up an LA90 discrete as a backup amp. The AHB2 that I had bought used needed repair after showing faults on cold power up.

No A/B compare right now. The clarity is great, but the bass is lacking, I mean really lacking driving the Revel 128Bes.
It sounds like there is a HPF filter in play, practically no bass listening to Massive Attack Mezzanine.

I checked the measurements in the review and it seems like a great 1kHz amplifier.
Perhaps, power measurements at multiple frequencies would have revealed something.

- Rich

I had the same feeling. But, as already said, the stellar measurements absolutely deny that feeling. I thought that the culprit were the ELAC DBR62s and my room too resonant. Now I have a Ncore based amp much more powerful and that feeling disappeared. Comparisons not possible anymore because my LA90 started to fail and I have returned it.

 

[antcollinet]

The existence of reactive loads seems to escape some of the illuminati. Though it has been obvious to pretty much anyone that many amplifiers are not ruler-flat even with the Stereophile simulated speakers, often clearly exceeding audibility limits.

You guys *really* need to be reading the reviews properly instead of just skimming. There is even a section titled "Reactive Load Testing" that points out this particular amp has no problem with them.


And then do your own testing in a way that controls for bias. Recording with a mic as pointed out by @staticV3 or doing proper level-matched blind testing.

Frankly it boggles my mind that people who have been here two years longer than I have still seem to think the need for that doesn't apply to them.

It is your failure to carry out proper evaluations, while still making your observations about sound characteristics, that leads to - not lynching - but correction of misapprehensions.

 

[dcolak]

You guys *really* need to be reading the reviews properly instead of just skimming. There is even a section titled "Reactive Load Testing" that points out this particular amp has no problem with them.


And then do your own testing in a way that controls for bias. Recording with a mic as pointed out by @staticV3 or doing proper level-matched blind testing.

Frankly it boggles my mind that people who have been here two years longer than I have still seem to think the need for that doesn't apply to them.

It is your failure to carry out proper evaluations, while still making your observations about sound characteristics, that leads to - not lynching - but correction of misapprehensions.

Ah yes, changing amp did not change the sound at all. Plenty of bass with LA90 discrete /s

 

[antcollinet]

Ah yes, changing amp did not change the sound at all. Plenty of bass with LA90 discrete /s

Well who knows. It might have done, unlikely though that might be.


But we'll never have any indication whether it has or not from sighted uncontrolled listening comparisons.