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Topping L30 Headphone Amplifier Review

nxnje

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@JohnYang1997
Can you please explain which improvements were made on the board?
This to know if I can sleep calmly on my post-2012 L30 (if I get the replacement) or if I should wait for february batch to be out.

Plus: is the E30 completely free from issues or ESD problems that could be trasmitted to the amp through RCA ports?

I'll be waiting for your reply for the final decision.
 
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Jose Hidalgo

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@JohnYang1997
Can you please explain which improvements were made on the board?
This to know if I can sleep calmly on my post-2012 L30 (if I get the replacement) or if I should wait for february batch to be out.

Plus: is the E30 completely free from issues or ESD problems that could be trasmitted to the amp through RCA ports?

I'll be waiting for your reply for the final decision.
Unfortunately John still doesn't know what is causing these issues. The december protections have been implemented "in the blind", because nobody has been able to replicate the ESD issues in a lab. So nobody can say that the L30 is completely free from these issues. I for one will wait for the february batch, unless John clearly states otherwise.

As for the E30, AFAIK there haven't been any fried E30s yet, so I guess we can safely say that the E30 is completely free from these issues. :)
 

Sukie

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Theres JDS Element II on amazon that sells to my country, 450e tho. While review on this site says amp is amazing, dac not so much.
Is element II worth it as amp/dac stack for a sensitive low Ohm HP and also 600Ohm ones?
Have a look at the review here.
I went to JDS page and selected atom chose my country atom amp is 99$ to my country postage is 44$ + import fees , yikes.
It certainly increases the price! I was happy to pay as there wasn't a lot on offer in that price range that was available in EU. Obviously the L30 then came out, but I'm perfectly happy with my Atom HPA.
 

Zikeee

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Have a look at the review here.

It certainly increases the price! I was happy to pay as there wasn't a lot on offer in that price range that was available in EU. Obviously the L30 then came out, but I'm perfectly happy with my Atom HPA.

Well i just bought Element II from amazon for 370+30shipping from Germany so no aditional fees, there were only 3 left in stock. Whats strange is the site says 450e + shipping but when you get to checkout its 370+ shipping, quite a nice surprise. So 2 left if anyone is looking to buy it.
 

JensH

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A 20kV ESD jolt can easily spark from the metal around the plastic to the shaft.

If I owned an L30 and it still works I would put some wire around the metal screw part around the shaft and connect the other end of the wire to the groundplane.
When the switches also are not grounded I would ground these to the groundplane as well.

Chances are the ESD problems may possibly be solved this way.
Of course the not (properly ?) functioning DC protection is not solved this way.
I fully agree with solderdude here.

According to a schematic of the input circuit, which someone put on the web some time ago, the wipers of the potentiometer go straight to the OPA1612 inputs. This is good for noise reasons, but dangerous in terms of ESD. Especially since the metal part around the shaft is not connected to ground.
If only Topping had used a potentiometer from the RK09L series and connected the ground pins to ground on the PCB.

Some have suggested to ground the L30. This may actually make the problem worse, since it will provide a solid return path for the ESD spark. The ESD spark can easily find a path around the volume knob, hit the shaft, move further to the wipers of the potentiometer with a small spark (internally in the potentiometer or externally) and thereby hit the inputs of the OPA1612.

The OPA1612 has ESD ratings of +/- 3 kV (human body model) and 200 V (machine model), which should be OK for handling what it will be subjected to during production, but far from sufficient if it is hit by a high voltage ESD spark.
I have been involved in a lot of electronic designs, which were tested with 8 kV contact discharge and 16 kV air discharge. This is fairly standard.

It is very disappointing that Topping has not done ESD tests before releasing the product. I agree with JohnYang1997 that the ESD test equipment is relatively expensive, as he wrote "It's neither cheap nor easy to get". I don't think it it too hard to get though and it could be a lot more expensive not to buy it and do proper testing.

I also did wonder about the old fashioned transformer and whether that was leagal at all, as someone hinted at previously. The standby consumption is way higher than it should be.

So where did the CE-mark come from?

I own an L30 and I do like the performance, but these basic flaws should have been eliminated before it was released to the market.
 

Veri

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I fully agree with solderdude here.

According to a schematic of the input circuit, which someone put on the web some time ago, the wipers of the potentiometer go straight to the OPA1612 inputs. This is good for noise reasons, but dangerous in terms of ESD. Especially since the metal part around the shaft is not connected to ground.
If only Topping had used a potentiometer from the RK09L series and connected the ground pins to ground on the PCB.
It's in a way kind of sad, that the binned pots they used for optimal channel balance, have come around to bite them in the ass; whereas choosing a run of the mill (worse performing) potentiometer might have eliminated the problem. Maybe.
 

Rock Rabbit

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Especially since the metal part around the shaft is not connected to ground.
But the thread and nut is in contact with metal chassis...so it seems better to ground chassis.

I have been involved in a lot of electronic designs, which were tested with 8 kV contact discharge and 16 kV air discharge. This is fairly standard.
But not the standard ESD test voltage.

I also did wonder about the old fashioned transformer and whether that was leagal at all, as someone hinted at previously. The standby consumption is way higher than it should be.
You're a designer so I hope you know the reason to use an AC transformer like in the famous O2 design (or JDS Labs Atom amp), or you have a better (less noisy) idea?. Maybe you think that an SMPS is better for ESD problems with the typical ferrite transformer leakage at HF ?
 

solderdude

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Not JensH but I'll take a shot.. (design railway measuring safety electronics for a living, those, like automotive, have some serious heavier requirements than home audio equipment)

It looks like only the incorrectly functioning DC protection has been addressed. Personally I would have liked to see the shaft grounded (easy to do).
That is IF ESD is the culprit. Not confirmed but likely. Needs to be established using test voltages of +/- 15kV.
In any case with the DC protection fixed the biggest problem (blowing up headphones in error) is fixed. 10 of 10000 units failing and being repaired is not a terrible thing. The expensive headphones blowing up are. That is fixed.

As for the choice of a transformer... lower leakage, less chance at a groundloop. Most SMPS have a much higher leakage current.
Yes, standby power is a bit higher, yes it is not a wide range, A dual voltage DC power supply would have been needed.

ESD test voltages from +/-2kV to +/-15kV are possible. Depends on which standard the manufacturer wants to adhere to with the CE certification. This is something the manufacturer can choose. It is easy to pass +/-4kV and can get you a CE certificate. It would be better to go for +/-15kV but would understand a manufacturers choice not to.
Adhering to minimal requirements (often for home appliances) is all that is required.
 
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Lorenzo74

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Get one and thank yourself that you live in this era and not a few years ago.
@amirm fully agree with you except the last 14 words... I would trade tech achievements in Audio of the last 10 years with this pandemic era. ;)
keep pushing this way Amir, do not change. Your latest post on Unifi2.0 are ASR manifesto.
consumers need an unbiased reference to a look at, to trust to.
There was a huge hole, you and ASR Exceptional members are filling it, with passion, day after day.
respectfully,
my Best
 

Billy Budapest

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I guess this is sort of a “public service message” for those people getting rid of their L30’s:

I have my Geshelli Archel 2.5 Pro listed in the classifieds. I was going to trade it in and still might, but would like to offer it up to forum members first. Eric
 
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raistlin65

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It is very disappointing that Topping has not done ESD tests before releasing the product. I agree with JohnYang1997 that the ESD test equipment is relatively expensive, as he wrote "It's neither cheap nor easy to get". I don't think it it too hard to get though and it could be a lot more expensive not to buy it and do proper testing.

Looks like it would have saved them a lot of money in this instance.

Not only what it's going to cost them in replacements of the L30s, but damage to the brand. They have had to work against the notion that Chinese audio brands are cheap or poorly made, and this is going to damage their brand image.
 

JensH

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I am making you speculate (?) with this request, since John hasn't yet responded and you said you have been involved in many electronic designs - even with the changes (2012 batch changes), do you still see potential ESD issues (with the same risk level) that can affect the amp, if not HP's?
If I understand it correctly, they have changed the "sensitivity" of the DC sensing circuit to get a safer protection mechanism. Whether this will react fast enough to protect the headphones, I don't know.
The DC sensing will always be a balancing act. You want it to react fast to any DC voltage, but you don't want it to react when playing e.g. low frequency music at high levels.

It seems likely that the problem starts with ESD destroying the input op-amp. I think that this issue should be addressed first. The DC protection is only a last resort if something fails, which hopefully should be very rare. Failures in semiconductors are generally not a common problem, but it does of course occur, even when working inside the recommended operation conditions.
 

JensH

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But the thread and nut is in contact with metal chassis...so it seems better to ground chassis.


But not the standard ESD test voltage.


You're a designer so I hope you know the reason to use an AC transformer like in the famous O2 design (or JDS Labs Atom amp), or you have a better (less noisy) idea?. Maybe you think that an SMPS is better for ESD problems with the typical ferrite transformer leakage at HF ?
The front plate doesn't look or feel like metal to me. If it had been metal, and properly connected to the other parts of the box, it would have been a different story.
I am not even sure that the metal box is electrically connected to the ground of the PCB. At least I can't measure any connection on my unit. My ohmmeter just reports "overflow".

The ESD voltage depends on which standard used.

AC transformers do have some advantages, but I am sure it could also work well with a switch mode power supply.
 

Upped

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Reply i got from apos about replacement hope everything goes well :)
 

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Roland68

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The front plate doesn't look or feel like metal to me. If it had been metal, and properly connected to the other parts of the box, it would have been a different story.
I am not even sure that the metal box is electrically connected to the ground of the PCB. At least I can't measure any connection on my unit. My ohmmeter just reports "overflow".
The front plate is in two parts. An anodized aluminum plate is screwed into the housing and the visible front panel is glued onto this.
The potentiometer is screwed to the aluminum front, but I don't think there is an electrical contact due to the anodization.
The same applies to the rear aluminum plate.

Such non-clean housing connected parts can in the case of ESD lead to undefinable states.
It could be that in the cases that occurred the potentiometer had a good electrical contact with the housing, the ESD blew through on the signal line up to the 1612.
 

SHENZHENAUDIO

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JohnYang1997

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The front plate is in two parts. An anodized aluminum plate is screwed into the housing and the visible front panel is glued onto this.
The potentiometer is screwed to the aluminum front, but I don't think there is an electrical contact due to the anodization.
The same applies to the rear aluminum plate.

Such non-clean housing connected parts can in the case of ESD lead to undefinable states.
It could be that in the cases that occurred the potentiometer had a good electrical contact with the housing, the ESD blew through on the signal line up to the 1612.
I received your PM, but we have purchased testing equipments.
The thing is the whole thing is floating/isolated from earth on its own. But when the RCA is connected the thing is earthed. This way creats a path for ESD current to flow. There are two potential fixes. One is to beaf up the inputs. Another is to manually creat a predetermined ESD current path. Maybe a combination of both.
 

dmac6419

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