Topping L30 Headphone Amplifier Review

[Dotcha]

So is this correct understanding on this discussion on ESD?
If this is the case (which is still unclear), can we make two contacts,
a. between housing and the cap shaft
b. between housing and the RCA plug (which works as a ground) to avoid ESD problem?
If so, making that kind of ground contact would be harmful in terms of noise performance of L30?

 

[JohnYang1997]

So is this correct understanding on this discussion on ESD?
If this is the case (which is still unclear), can we make two contacts,
a. between housing and the cap shaft
b. between housing and the RCA plug (which works as a ground) to avoid ESD problem?
If so, making that kind of ground contact would be harmful in terms of noise performance of L30?

b may work, which is my first instinct. But the resistance of the housing may be higher than going through the opamp. So it needs further investigation.

 

[Dotcha]

Or... as @solderdude suggested, making pot shaft or shaft nut have contact with the housing,
and adding additional ground to the L30's housing could help?
in this way, RCA plug is not connected with housing or the pot shaft,
and pathway for ESD to not pass through PSB / OP-amp could be provided...

 

[JohnYang1997]

View attachment 105980
Or... as @solderdude suggested, making pot shaft or shaft nut have contact with the housing,
and adding additional ground to the L30's housing could help?
in this way, RCA plug is not connected with housing or the pot shaft,
and pathway for ESD to not pass through PSB / OP-amp could be provided...

That's impossible to achieve with current form of the device. You can do it yourself if you know your stuff.

 

[Dotcha]

b may work, which is my first instinct. But the resistance of the housing may be higher than going through the opamp. So it needs further investigation.

Sorry, I didn't fully get it. If the resistance of the housing is higher, isn't it the cause that leads ESD to pass through the op-amp?

hmm.. one guess is that, the anodizing treatment was not even in the 'internal' of the housing, and have caused different surface resistance of the housing.
Maybe housing of L30 units that have showed failure might had higher surface resistance than other units.

 

[JohnYang1997]

Sorry, I didn't fully get it. If the resistance of the housing is higher, isn't it the cause that leads ESD to pass through the op-amp?

hmm.. one guess is that, the anodizing treatment was not even in the 'internal' of the housing, and have caused different surface resistance of the housing.
Maybe housing of L30 units that have showed failure might had higher surface resistance than other units.

Don't worry too much.

 

[Dotcha]

That's impossible to achieve with current form of the device. You can do it yourself if you know your stuff.

That's true. I'm thinking about soldering a wire to the pot shaft nut, and ground it directly to some resorvoir...
BTW my knowledge on electronics is short, and I wonder if grounding the housing directly to the RCA plug could be harmful for the performance of L30 in terms of noise... if so, It would be better to ground the housing - shaft with a different ground wire than RCA cable...

 

[ragecandy]

Anyone bought from Angelears Audio store? don't know if all sellers are gonna handle it the same way, and I really don't wanna have to ship it back to China x.x

 

[JohnYang1997]

That's true. I'm thinking about soldering a wire to the pot shaft nut, and ground it directly to some resorvoir...
BTW my knowledge on electronics is short, and I wonder if grounding the housing directly to the RCA plug could be harmful for the performance of L30 in terms of noise... if so, It would be better to ground the housing - shaft with a different ground wire than RCA cable...

Oh that way don't do it.

 

[Dotcha]

Oh that way don't do it.

Oh OK! Thanks!

 

[iucoen]

@JohnYang1997
I bought my L30 from Drop. Will it be possible to get a replacement through Drop? Unlike other vendors Drop will not a have any spare L30s in stock for replacement, so I wonder how the replacement process will work.

 

[JohnYang1997]

@iucoen Hi just checked, ask shenzhenaudio.

 

[SHENZHENAUDIO]

2005 mine start with

Yep, pls.

 

[Dotcha]

I've just got reply from aoshida HIFI store at aliexpress.
They offered me two conditions - refund or replacement.
I chose replacement, and their reply was kind and prompt.
I appreciate topping and their distributers for the recall process, and especially to @JohnYang1997 for his continued effort on this issue,
although this issue is still ongoing and not all problems are solved yet.
Hope everyone who got their headphones / speakers damaged during using L30 get their damage covered well.

 

[Blizz]

Just to be sure we can exchange them whenever? I want to wait for the next revision that addresses the ESD issues since I do get shocked a lot.

 

[JohnYang1997]

Everything needed to be said have already been said. I will not reply everytime someone asks me. If you have any issue about replacement just ask your seller. It is that simple.

 

[highpurityusbcable]

I've just got reply from aoshida HIFI store at aliexpress.
They offered me two conditions - refund or replacement.
I chose replacement, and their reply was kind and prompt.
I appreciate topping and their distributers for the recall process, and especially to @JohnYang1997 for his continued effort on this issue,
although this issue is still ongoing and not all problems are solved yet.
Hope everyone who got their headphones / speakers damaged during using L30 get their damage covered well.

I also got a reply overnight and can endorse their service. I'm leaning towards the replacement because after all this is a great amplifier and something like this happened only once between me and Topping. I think I'll choose to trust on this one.
Did you already send pictures of destroyed L30?

 

[JensH]

That's true. I'm thinking about soldering a wire to the pot shaft nut, and ground it directly to some resorvoir...
BTW my knowledge on electronics is short, and I wonder if grounding the housing directly to the RCA plug could be harmful for the performance of L30 in terms of noise... if so, It would be better to ground the housing - shaft with a different ground wire than RCA cable...

Oh that way don't do it.

Why not?
Except that the "reservoir" needs to be the ground of the PCB.
If you connect the pot shaft pot and thread to ground, e.g. at the ground connection of the headphone jack, you will have a known path for ESD pulses hitting the shaft. If the RCA's are grounded, the ESD pulse will find its way out on the RCA shields. If the RCA's are not grounded, it may find its way out through the power supply or through the RCA's, depending on what is the "easiest" way.

The isolated box also seems like a risky approach. You should check where the spark will fly, when the voltage is high enough. If it jumps to the pot shaft, and you connect it as descibed above, it will probably be OK, but if it jumps to sensitive parts inside the box, you could still have a problem.

You need to get the return path under control to solve the ESD issue!
I hope you will solve the ESD issue as well as the DC protection. Otherwise I would be reluctant to seek a replacement, since only a part of the problem has been solved.

 

[Dotcha]

I also got a reply overnight and can endorse their service. I'm leaning towards the replacement because after all this is a great amplifier and something like this happened only once between me and Topping. I think I'll choose to trust on this one.
Did you already send pictures of destroyed L30?

I only sent them current L30 with serial number. I did not destroy them yet.

 

[JohnYang1997]

Why not?
Except that the "reservoir" needs to be the ground of the PCB.
If you connect the pot shaft pot and thread to ground, e.g. at the ground connection of the headphone jack, you will have a known path for ESD pulses hitting the shaft. If the RCA's are grounded, the ESD pulse will find its way out on the RCA shields. If the RCA's are not grounded, it may find its way out through the power supply or through the RCA's, depending on what is the "easiest" way.

The isolated box also seems like a risky approach. You should check where the spark will fly, when the voltage is high enough. If it jumps to the pot shaft, and you connect it as descibed above, it will probably be OK, but if it jumps to sensitive parts inside the box, you could still have a problem.

You need to get the return path under control to solve the ESD issue!
I hope you will solve the ESD issue as well as the DC protection. Otherwise I would be reluctant to seek a replacement, since only a part of the problem has been solved.

I'm not comfortable recommending people who aren't experienced doing these kind of work.

And again, if the headphones don't burn, what's the problem? You'll get a replacement if your unit fails.

Lastly, just now we finally managed to reproduce the ESD problem and identify the failing components. There will be solution soon. For you personally, of course you can wait until the ESD issue being solved. It's all up to you. You already have all the information you needed to make a decision.