Topping LA90 Discrete arriving in 1-2 days. Question vs. LM3886 version

[sarieri]

There is no difference between amps made pre July 15 and post July 15 - Topping.

Sure 10 people in a group chat had broken amps.
How many of those amps has Topping sold?
What is the usual failure rate of manufactured electronics like amplifiers?

Your figure is useless

This is the situation: A known issue that can arise is popping which can be fixed by a module replacement.

Some guy got three (3) REPLACEMENTS before he didn't need another...
Since Topping knows what the issue is, and they fixed his amp, shouldn't it be impossible to need three?

You believe what you want. I gain 0 utility from your amp, failed or not.
And No manufacture on earth would ever tell you how many revisions they did on their products especially those failed ones whatsoever. The underlying logic is so simple that I don't even bother to explain.
I understand that selling ideas to people often times is like pointing to their noses and tell them they are stupid. Because any infomation yet disclosed are most likely out of people's knowledge, sometimes hard to get along with. But, in any case, this forum is in many sense in persuit of truth.

In case someone else wonder where I got all this information. Here is the screenshot of a private converstation between me and JohnYoung. You can google translate it.

 

[mike7877]

Ask Topping, but I don’t think you will have a reply

As I said, from Topping

 

[AltoVariago]

As I said, from Topping

Good luck.

Such a massive report of failures and the company not replying publicly does not look good to me.

At least for our western standards of consumer care.

 

[TurtlePaul]

Topping also had PA5 amp modules fail. They worry that people are out to steal their designs so they encapsulate opamp circuits in plastic modules. Then when the opamps get hot they die. They really need to stop doing this because their paranoia is costing their customers and has already impacted their reputation. Plenty of companies which make 110 dB+ SINAD devices don’t feel a need to encapsulate their circuits.

 

[mike7877]

Topping also had PA5 amp modules fail. They worry that people are out to steal their designs so they encapsulate opamp circuits in plastic modules. Then when the opamps get hot they die. They really need to stop doing this because their paranoia is costing their customers and has already impacted their reputation. Plenty of companies which make 110 dB+ SINAD devices don’t feel a need to encapsulate their circuits.

Are you sure they're not impregnated or lined with metal to improve snr?
A plastic cover is hardly going to get in the way of someone who wants to look under it... just the average consumer who doesn't want to potentially wreck their gear.
Also, oamps and the circuits driving them are low power, and their performance suffers at high temps, not necessarily their longevity. For an opamp to break in a month or two, it'd have to be 150-175C+, and performance would be horrible in the mean time.
If mounted to compensate, an opamp could be heatsinked under a plastic cover, too

 

[ahofer]

Let's definitely fight about this.

 

[antcollinet]

Yeah that brought up nothing

edit for clarity: nothing relevant
in case you're too lazy to check that there's nothing relevan (I mean, you could explain what a module is - clearly you know, but you passive aggressively sent a search result instead, which leads to these few posts here in this thread, and the rest to threads of other device)

Lets see if I can help here with a potted history.

First there was the PA5 with significant reports of failures:

Poll for Topping PA5 owners only please.

Poll for PA5 owners to report product defects. Discussion for any solutions. I think it would be useful to get a handle on some numbers to estimate just how wide spread the issues are. Addendum: Here is Topping's response to the PA5 issues...

www.audiosciencereview.com

Eventually it was discontinued, and has now been replaced with the PA5 II - however it left a sour taste.

Then when the LA90 discrete was launched there seemed to be a similar problem - though it was less clear

Topping LA90 Discrete Amplifier Review

This morning I received an email from Shenzhenaudio.com with discounts, ending in 6 days - amongst other products - Topping LA90D @ $679 (discount $120) 2 year warranty, Free shipping, tax and import duty paid That's not really fair for the early adopters who usually are the hottest fans of the...

audiosciencereview.com

Then the discrete became unavailable (Probably the reason for your order delay). In answer to a question about whether people should wait for a fixed version, John Yang (A topping product manager), suggested people needed to wait before placing an order.

Ask me questions.

I would hope that I didn't inspire such hyperbole. Although, I would obviously appreciate some improvement, "thoroughly inferior" was not the sentiment I I sought to convey. The trade off between performance and the mild inconvenience of having to adjust the angle, and a few repeated button...

audiosciencereview.com

The speculation - now that Topping has started shipping again - is that if there was any issue, it has now been resolved. However as far as I know there has been no definitive statement from topping.

They could significantly improve their standing here with some clearer communication @JohnYang1997


Hope that helps.

 

[antcollinet]

A plastic cover is hardly going to get in the way of someone who wants to look under it

It isn't just a plastic cover. Under the plastic the module is completely encased in potting compound (like a form of resin).

It still didn't help though. One of our members here @gamerpaddy cut one out, reverse engineered it, and created replacement PCB's to enable people to fix their PA5s. A local hero in my book.

and their performance suffers at high temps, not necessarily their longevity

The theory is that differential thermal expansion of the PCB/resin rips components off the PCB (or at least breaks connections between component and pcb). In any case, the fix created by @gamerpaddy confirms that the module potting is at fault - since so far none of his non potted pcbs has failed.

 

[sarieri]

Just to make the data point clearer. Two of my LA90Ds were sent back on July 26th, fixed at Auguest 3rd. And their After-sales confirmed with me on Sep 4th that the reason of these two failed units was failed modules. They were replaced with new modules.

 

[mike7877]

Let's definitely fight about this.

Just theorizing - I'm always open to ideas... like the ones in the couple posts above this one - they do a good job explaining what could be wrong. I think it's a likely explanation

 

[mike7877]

Lets see if I can help here with a potted history.

First there was the PA5 with significant reports of failures:

Poll for Topping PA5 owners only please.

Poll for PA5 owners to report product defects. Discussion for any solutions. I think it would be useful to get a handle on some numbers to estimate just how wide spread the issues are. Addendum: Here is Topping's response to the PA5 issues...

www.audiosciencereview.com

Eventually it was discontinued, and has now been replaced with the PA5 II - however it left a sour taste.

Then when the LA90 discrete was launched there seemed to be a similar problem - though it was less clear

Topping LA90 Discrete Amplifier Review

This morning I received an email from Shenzhenaudio.com with discounts, ending in 6 days - amongst other products - Topping LA90D @ $679 (discount $120) 2 year warranty, Free shipping, tax and import duty paid That's not really fair for the early adopters who usually are the hottest fans of the...

audiosciencereview.com

Then the discrete became unavailable (Probably the reason for your order delay). In answer to a question about whether people should wait for a fixed version, John Yang (A topping product manager), suggested people needed to wait before placing an order.

Ask me questions.

I would hope that I didn't inspire such hyperbole. Although, I would obviously appreciate some improvement, "thoroughly inferior" was not the sentiment I I sought to convey. The trade off between performance and the mild inconvenience of having to adjust the angle, and a few repeated button...

audiosciencereview.com

The speculation - now that Topping has started shipping again - is that if there was any issue, it has now been resolved. However as far as I know there has been no definitive statement from topping.

They could significantly improve their standing here with some clearer communication @JohnYang1997


Hope that helps.

Good to know. Hopefully this was the reason for my item's delay
I heard from Topping there were no issues with it, though in the same breath there were never any systemic issues, so...
I'm not brave enough to open the cover on mine to see if it's goop free... unless the goop isn't attached to the cover, then I might try it.. does anyone know they come off?
If there's no useless putty on the newer versions, it would be good for all to know, I think

 

[antcollinet]

Good to know. Hopefully this was the reason for my item's delay
I heard from Topping there were no issues with it, though in the same breath there were never any systemic issues, so...
I'm not brave enough to open the cover on mine to see if it's goop free... unless the goop isn't attached to the cover, then I might try it.. does anyone know they come off?
If there's no useless putty on the newer versions, it would be good for all to know, I think

The fix for the PA5 2 (as I understand it) was to move the op amps out of the module onto the main PCB leaving the passive components in the (still potted) module.

I've no idea what (if anything) they've done on the LA90 discrete.

Personally my view is there should be no potting compound anywhere near Toppings devices. I've said as much to John Yang.

 

[sarieri]

The fix for the PA5 2 (as I understand it) was to move the op amps out of the module onto the main PCB leaving the passive components in the (still potted) module.

I've no idea what (if anything) they've done on the LA90 discrete.

Personally my view is there should be no potting compound anywhere near Toppings devices. I've said as much to John Yang.

But my RA3 still failed. Lasted for only one day. RA3 is pretty much a PA5 II in a larger chassis right?
I disassembled my RA3 and one of the module seems to have a bump, so I guess the module failed. Not sure if the new design completely rule out the issue. That being said, I don’t hear as much people complaining about failed RA3 so maybe mine is a bad apple. At least not as much people comparing to those with LA90Ds.

 

[antcollinet]

But my RA3 still failed. Lasted for only one day. RA3 is pretty much a PA5 II in a larger chassis right?
I disassembled my RA3 and one of the module seems to have a bump, so I guess the module failed. Not sure if the new design completely rule out the issue. That being said, I don’t hear as much people complaining about failed RA3 so maybe mine is a bad apple. At least not as much people comparing to those with LA90Ds.

Could just be a one off (all products have failures)

On the other hand there is no local distribution of the RA3 outside of Asia at the moment as far as I know, so volumes are probably pretty low - it may take time to get a good feel one way or the other.

And Like I say - topping are idiots (IMO) for continuing to use potted modules.

 

[mike7877]

The fix for the PA5 2 (as I understand it) was to move the op amps out of the module onto the main PCB leaving the passive components in the (still potted) module.

I've no idea what (if anything) they've done on the LA90 discrete.

Personally my view is there should be no potting compound anywhere near Toppings devices. I've said as much to John Yang.

I think the reason for it on low powered stuff is that vibrations from the sound can cause a feedback of sorts, and with -120dB SNR/THD+n, the effect from these vibrations might be significant. To my memory, I've seen a lot of audio stuff with components secured this way, and it doesn't usually result in bad things happening.

I haven't had the case/heatsink of my LA90 Discrete rise to more than 40C yet, even when playing music loudly. My speakers are a sealed design, so not too reactive, and 8 ohms with no low dips anywhere, so that could be why.. But even still, I find it hard to believe the LA90 Discrete heats up past 50C for anyone with speakers at least 4 ohm nominal 3 ohm minimum who's playing music that's not clipping. I guess this isn't related too much to the temperature and expansion/contraction of the OP amp module sections anyway, because usually, whether the amp is being worked hard (or hardly working), their power dissipation remains relatively constant. Obviously not constant-constant, like class-a constant, but relatively constant compared to the outputs- significantly less change.

If my amp breaks I'll investigate the still working channel and see how much the OP amp temperature swings.

This reminds me of 2008 - nvidia had a bad batch of chips they decided to bump the voltage on instead of remanufacture. In laptops which got turned on and off many times per day, this increased temperature swing caused the GPU to slowly detach from the motherboard with time. There was a HUGE lawsuit about it. I think it was the G92 chip?

I guess it's good to know that the fix is pretty easy if the problem ever does arise in the future.

 

[mike7877]

Does anyone know if Topping has a way to know if I opened the case of my LA90 Discrete? I have an IR thermometer I'd like to point at a few things while loading the amp in different ways - do some experimentation and report back

 

[sarieri]

Does anyone know if Topping has a way to know if I opened the case of my LA90 Discrete? I have an IR thermometer I'd like to point at a few things while loading the amp in different ways - do some experimentation and report back

They won’t care if you open the chassis or not. Mine were sent back even without few screws since I forgot to put all screws in after disassemble for troubleshooting.

 

[antcollinet]

I think the reason for it on low powered stuff is that vibrations from the sound can cause a feedback of sorts,

Not with solid state electronics. There are no microphonic effects there. That's a myth hanging over from the days of tube amplification.

Glueing components is sometimes used in order to pass mechanical vibration tests - but not for audible reasons - it is to stop component legs fracturing from the vibrations. And these tests are many 1000's of times more severe than any vibration picked up from sound in the air

However Toppings own stated reason for the potting is IP protection. (See the "ask me" thread)

And when you have components and PCB fully embedded (this is not just a dab of glue fixing two components together, or a component to a PCB) in a hard (non flexible) resin, then even a tiny amount of differential expansion will create huge mechanical stresses.

Yes it can be done, but careful choice of materials to suit the application, and even more-so accelerated life testing are essential to prove it works without impacting reliability. In a previous life we used in in a product - then stopped using it again very quickly. After delivery service costs were huge, and that was on a low volume product.

 

[restorer-john]

Let's definitely fight about this.

 

[ken.montero96]

I won’t speculate too much here, but my info came directly from JohnYoung himself. Before I sent Topping those two failed LA90Ds, he explicitly pointed out that LA90Ds failed so far were due to modules. “Sealing them in plastic chambers created lots of troubles” he said. And I asked whether this will happen after replacing modules and he said they made refined modules. He then said that he will talk to after sales and informed me that modules made after July 15th will be good to go later in that conversation

I won’t speculate too much here, but my info came directly from JohnYoung himself. Before I sent Topping those two failed LA90Ds, he explicitly pointed out that LA90Ds failed so far were due to modules. “Sealing them in plastic chambers created lots of troubles” he said. And I asked whether this will happen after replacing modules and he said they made refined modules. He then said that he will talk to after sales and informed me that modules made after July 15th will be good to go later in that conversation

topping is hiding something again. there is lm3886 on the sealed chamber serving as vas. I saw it in a japanese video