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Topping L30 Headphone Amplifier Review

Jose Hidalgo

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I think you read that wrong. December batch has changes due to a case of failure from November, any changes done to the design NOW would be effective in units produced February at the earliest.
No, sorry. If you read all of John's comments, you'll see that he still doesn't know for sure what's causing these issues. He has been saying that repeteadly over the last few days. Some protections may have been implemented recently, but nobody knows if they will solve the problem. Nobody even knows if it's a faulty batch, a faulty OPA, of something else. That is the real problem here : we still don't know what we're dealing with.

John has said that he will keep on examining amps and hopefully implementing NEW protections... which won't be physically implemented before the february batch (possibly even later). That is what he said.

As has already been discussed in the thread, the newer units have improved DC voltage regulation. This prevents damage to headphones with amp failure.
It can help prevent damage in some cases, but like John said, he's still unsure of the origin of all these issues. He hasn't gotten to the bottom of this yet.
 
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As has already been discussed in the thread, the newer units have improved DC voltage regulation. This prevents damage to headphones with amp failure.
Sorry, but I don't have as much trust in words as you do. Only time can tell how improved this regulation is. As much as I want to believe, one, two, three or ten units could still miss the qc.

@threni ,my choice will be optimal, of course.They won't replace eardrums too, most likely. Still made me search for them on aliexpress.
 

Rick63

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It's the cheapest for them, no shipping cost or electric scraps.
It's a difficult situation for sure. While I understand why Topping would want to minimize their losses on this, I'd feel real bad for someone who bought a suspect unit on the used market only to subsequently have their headphones destroyed. Or worse yet have their hearing damaged.
 

raistlin65

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Sorry, but I don't have as much trust in words as you do. Only time can tell how improved this regulation is. As much as I want to believe, one, two, three or ten units could still miss the qc.
Then don't. Ask for a refund. Or if they'll only do an exchange, sell it as NIB on eBay.

I just don't see that you have any other option if you don't trust that there's improved DC voltage protection.
 
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IMHO we still have to wait (I'm doing it) next @JohnYang1997 statement about this.
Check which improvements have been implemented in serials 2012 and above and whether they deal with both the DC problem and the ESD problem.
 
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No, sorry. If you read all of John's comments, you'll see that he still doesn't know for sure what's causing these issues. He has been saying that repeteadly over the last few days. Some protections may have been implemented recently, but nobody knows if they will solve the problem. Nobody even knows if it's a faulty batch, a faulty OPA, of something else. That is the real problem here : we still don't know what we're dealing with.

John has said that he will keep on examining amps and hopefully implementing NEW protections... which won't be physically implemented before the february batch (possibly even later). That is what he said.


It can help prevent damage in some cases, but like John said, he's still unsure of the origin of all these issues. He hasn't gotten to the bottom of this yet.
I reread the facebook post and might understand what you mean. It is not guarenteed that 2012 and newer revision will not have whatever catastraphic fail, but since that revision there is better protection in place so that the amp won't take the headphones with it. But it is not clear if the cause for failing is known.
 
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For those concerned to loose the stack symetry. I'm very ok with this look. Also they put in an auto off switch, fun fact: Monolith active 6 Watt (l30 8w), turned off we have 0.8w vs 5 watt at the l30. I will keep the e30 since it does it's job and I like Akm, who knows when they rebuild their factory.
PXL_20210113_163820951.jpg
 
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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.
 

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. :)
 

SJ777

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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.
 
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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.
 
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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
 
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