Topping LA90 Discrete Amplifier Review

[Sokel]

I have seen so many strange stuff (newbie) measuring and scrutinizing with stuff that I suspect everything from now on.
Even simple things,a quick example:

My nephew has desktop gear,one of the connections was pseudobalanced so he got a Cordial cable,female Bal > RCA.
From the time he connected his stuff something felt strange,so he ask the uncle (me) to search stuff.
I searched everything and the last thing I did was to have a look at the cable.
So,it had 2 thin cables and the shield.

XLR plug:
Pin 2 (hot) was BOTH white and red cable
Pin 1 (ground) half of the shield
pin 3 (cold) the other half of the shield

RCA plug
hot was white and red
ground was the shield.

Although the connection is not wrong,rearranging them to more sane way ( single wire to hot on both ends,etc) made the noise go.
I don't know the mechanism behind it but it felt right to follow the usual way.

That's why I'm asking,strange things happen all the time.

 

[aphysically]

Can you please describe your chain,starting from the AC plugs all the way to your speakers including interconnects?
Music gender preference?

Any other non-audio devices in the room (A/C,led strips,etc)?
I'm not trying to find faults of your own,just curious if something is stressing them (which of course shouldn't,any consumer device should be immune to environment to a sensible extent).

D90SE connected to computer via USB, fed to A90D by XLR, fed by XLR to dual mono LA90D in passthrough mode, eaching going to a KEF R3. All plugged into a regular surge protector. I listened near field so my volume was always on the very quiet end. Other electronics in room was only the PC and an APC UPS (runs the PC, audio equipment not connected to it, is >8 feet away from it). When testing the failure all of this was switched out, trying different outlets in different rooms and different cables and no input to the LA90D connected at all.

Sokel,
having once used valve gear I know that putting a valve phono stage near a PSU can cause hum problems but the LA90d is housed in a sturdy aluminium case, there should be no interference externally.

aphysically - can you not post on this forum or another for someone with the nec. experience to take a look at your amps, that is the solution. Probably all it will take is a simple continuity check to identify the problem.

So you get the first amp replaced with another, if it's a replica of the first the same problem will occur.

It's not that I doubt anyone's ability to diagnose the failure upon opening it up; it's just that by not doing so I want to preserve as seamless as possible the return under warranty for refund. That should get the amps to Topping if they want to look at it as well, as I bought through their recommended NA retailer - Apos. My warranty experience when I did everything "right" is interesting independent of my unfortunate failures. If I had a complaint right now it's that the response times are being painfully slow, but it's a little too early to judge. I'll update if there's something more substantial on the return process.

 

[Down South]

D90SE connected to computer via USB, fed to A90D by XLR, fed by XLR to dual mono LA90D in passthrough mode, eaching going to a KEF R3. All plugged into a regular surge protector. I listened near field so my volume was always on the very quiet end. Other electronics in room was only the PC and an APC UPS (runs the PC, audio equipment not connected to it, is >8 feet away from it). When testing the failure all of this was switched out, trying different outlets in different rooms and different cables and no input to the LA90D connected at all.


It's not that I doubt anyone's ability to diagnose the failure upon opening it up; it's just that by not doing so I want to preserve as seamless as possible the return under warranty for refund. That should get the amps to Topping if they want to look at it as well, as I bought through their recommended NA retailer - Apos. My warranty experience when I did everything "right" is interesting independent of my unfortunate failures. If I had a complaint right now it's that the response times are being painfully slow, but it's a little too early to judge. I'll update if there's something more substantial on the return process.

So you will never know the problem/s and it's highly likely that the same problem/s will happen again - what then?

 

[anphex]

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

Hi! Since some ongoing discussion in this thread I wanted to create a poll where people could vote and then share their experiences. I have two LA90D in monoblock configuration, figuring these would be the last amps I'd ever need in my lifetime if vented well. Because of the above mentioned...

www.audiosciencereview.com

Please vote there for visibility and share your story. This thread is derailing a little.

 

[YesChickenNuggets]

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

Hi! Since some ongoing discussion in this thread I wanted to create a poll where people could vote and then share their experiences. I have two LA90D in monoblock configuration, figuring these would be the last amps I'd ever need in my lifetime if vented well. Because of the above mentioned...

www.audiosciencereview.com

Please vote there for visibility and share your story. This thread is derailing a little.

I have a feeling it's all the purify/hypex/benchmark employees who are worried that their product is now completely irrelevant and obsolete.

Calm down guys, back to the drawing boards. I have faith in you.

 

[geekosa]

D90SE connected to computer via USB, fed to A90D by XLR, fed by XLR to dual mono LA90D in passthrough mode, eaching going to a KEF R3. All plugged into a regular surge protector. I listened near field so my volume was always on the very quiet end. Other electronics in room was only the PC and an APC UPS (runs the PC, audio equipment not connected to it, is >8 feet away from it). When testing the failure all of this was switched out, trying different outlets in different rooms and different cables and no input to the LA90D connected at all.


It's not that I doubt anyone's ability to diagnose the failure upon opening it up; it's just that by not doing so I want to preserve as seamless as possible the return under warranty for refund. That should get the amps to Topping if they want to look at it as well, as I bought through their recommended NA retailer - Apos. My warranty experience when I did everything "right" is interesting independent of my unfortunate failures. If I had a complaint right now it's that the response times are being painfully slow, but it's a little too early to judge. I'll update if there's something more substantial on the return process.

Is there a difference between :
D90SE -> LA90D
and
D90SE -> A90D -> LA90D
?

What is the improvement with adding the A90D in the system ?

 

[aphysically]

Is there a difference between :
D90SE -> LA90D
and
D90SE -> A90D -> LA90D
?

What is the improvement with adding the A90D in the system ?

I use it as a headphone amplifier, but I also have ambitions to eventually hook up my work computer's RCA output from an old unused ODAC to the RCA input.

 

[elsonido]

I have one LA 90 D, and have a second on order. I am using the pre-90 and the plan has been to bridge and run mono. Speakers are Focal Aria K2 906, so not a bad load, but I am concerned that most problems, anecdotally from the poll here, tend to occur with monoblocks. I love my little amp, more power would be welcome as it is in a large room. The one amp has been running without issue for weeks. Is it a mistake to add the second?

Update, I canceled the order for the second. Looks like their most recent run may be sold out and I had ample time to cancel. If it ain’t broke…. It has been rock solid as a stereo unit thus far.

 

[geekosa]

I have one LA 90 D, and have a second on order. I am using the pre-90 and the plan has been to bridge and run mono. Speakers are Focal Aria K2 906, so not a bad load, but I am concerned that most problems, anecdotally from the poll here, tend to occur with monoblocks. I love my little amp, more power would be welcome as it is in a large room. The one amp has been running without issue for weeks. Is it a mistake to add the second?

I'm using the LA90D on a pair of Focal Sopra N2, and I don't see the need for more watts for now.

Do you listen music so loud you need more than 40 Watts ?

 

[jagwap]

THX technology is different design altogether.

Are you sure it isn't? It is similar in measurement and there are not many that can do this low THD at higher frequencies. The dual cables to the output inductor could also be the post coil feedback to correct for the bridge mismatch that is the core of the THX patent.

Then if not, what are they using in here? The only other topology I have seen to match this in AB is Halcro, and that needed a huge amount of cascodes, Hawksford feedforward and an RF feedback connection that would never fit in this design. The National Semiconductor "Overture" amp front end ICs had a flat THD curve, but it was higher than this, and they are hard to hide being 15 pin SIL heatsink mounted packages. Maybe that is what is in the potted boxes.

Does not look like a clamp. The transistors are screwed on to the heat sinks. Looks like a spacer. Why so angry?

It could be temperature compensation for the output bias. But an SMT sensor next to the middle pin of the output transistor probably has a better thermal track as it is the same copper as the heatsink plate rather than through the transistor plastic body.

 

[elsonido]

I'm using the LA90D on a pair of Focal Sopra N2, and I don't see the need for more watts for now.

Do you listen music so loud you need more than 40 Watts ?

A 20’ distance at many points, so it’s a borderline use case. I may try and cancel. Thanks for the reply!

 

[notsodeadlizard]

I'm using the LA90D on a pair of Focal Sopra N2, and I don't see the need for more watts for now.

Do you listen music so loud you need more than 40 Watts ?

Focal Sopra 2?
Thank you, that was convincing (

 

[tedmingo]

Why is there a volume control? Ya, I know you can bypass it, but has me shaking my head. The crosstalk and the external power supply has me concerned One would not drive my speakers adequately. You are much better off with a made in the good old USA Benchmark AHB2.

 

[Down South]

Why is there a volume control? Ya, I know you can bypass it, but has me shaking my head. The crosstalk and the external power supply has me concerned One would not drive my speakers adequately. You are much better off with a made in the good old USA Benchmark AHB2.

Why is there a volume control - why not, the only question surely is - does it do it's job equally on both channels and does it impose any 'character' on the sound.

You must have very inefficient speakers and or a very big room. DYK that most speakers and a lot of expensive gear has been made in China for some time now.

 

[Abrise]

I am a bit confused by the input sensitivity. It says 7.3Vrms for low gain and 2.2Vrms for high gain . Most DAC will provide 4V . What to use then? the low gain or high gain.
If you use the low gain you may never reach the max power. If you use the high gain what would happen if you push your DAC to more than 2.2V 3.5V for instance by mistake?

 

[AaronJ]

what would happen if you push your DAC to more than 2.2V 3.5V for instance by mistake?

This is a problem with any amp. The low gain option is measurement-chasing.

 

[DrDen]

I am a bit confused by the input sensitivity. It says 7.3Vrms for low gain and 2.2Vrms for high gain . Most DAC will provide 4V . What to use then? the low gain or high gain.
If you use the low gain you may never reach the max power. If you use the high gain what would happen if you push your DAC to more than 2.2V 3.5V for instance by mistake?

That’s why you should use low gain and not worry. I do this way. Never even tried to “reach the max power”.

 

[Abrise]

That’s why you should use low gain and not worry. I do this way. Never even tried to “reach the max power”.

Yes but then the max power is quite low for 4V input you'll get in low gain - a multiplicator of around 3- a max of 18W on 8 Ohm. It looks quite small. Some DAC with max 5v would give 28w, still small and psychologically not enough.

 

[DrDen]

Yes but then the max power is quite low for 4V input you'll get in low gain - a multiplicator of around 3- a max of 18W on 8 Ohm. It looks quite small. Some DAC with max 5v would give 28w, still small and psychologically not enough.

My DAC has just 3,8V RMS, I use it with not that much attenuation as my previous DAC (5V RMS). Less digital attenuation — better sound.

 

[staticV3]

What to use then? the low gain or high gain.

Use the lowest gain that allows you to reach satisfying volume levels.