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Topping L30 Headphone Amplifier Review

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. Pretty sure that, no, 9038s should not be connected to any amp (unless you provide it ground potential with some sort of DIY-way of cabling

but, balanced connection without ground like common thing? i heard it often used to eliminate ground loops, for example
 

Veri

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but, balanced connection without ground like common thing? i heard it often used to eliminate ground loops, for example
It's because it is a 2.5mm connection meant to be connected to headphones. Not meant for line-out. 4.4mm pentaconn for example could support a proper grounding pathway if I'm not mistaken. But 2.5mm cannot, it just has positive and negative signal effectively doubling power, but that's it.
 

Shadez

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No, no... The gain is determinated by its internal circuit. Gain values have no relation to input voltage. However power output is related to the power supply, output circuit components and load. Buut for the amp reaches its highest power out the output circuit should be feed with a voltage value that allows it driven a specific load without saturating (clipping). Example: JDSLABS Atom has a higher gain than L30 and a similar voltage power supply output (+-15V), this higher gain makes it reachs 270mW over 300 ohm and 1.1W over 32 ohm - clipping. L30 being feed with 2V reaches only 110mW on 300ohm but 1W over 32ohm without clipping. This is possible because L30 has a higher capability to drive heavy loads than Atom. If you feed more voltage to L30 it will provide more power but Atom won't... Look at Atom+ and a10h (it has almost the same output circuit from L30) reviews, mainly the THD vs voltage output. A10h has a much better behavior...
Sorry any grammar mistake, I'm not native English speaker x.x[/Q
 

Shadez

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thanks, so as an example my ifi Zen Can can run quite happily at full power with 2v in, so is this just a different design as many Amps mid and upwards do not rely on the DAC input power to reach their full potential.
 

Spiral_Architect

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Recently purchased the L30 to pair with my E30 for a compact high-quality stack. The S/N I got is 2101; i've skimmed through the thread and found various information on two successive revisions that the unit underwent, to related to DC protection circuit and sensitivity to ESD. I gather that all units with 2012+ S/N should be in one way or the other fixed at the factory and considered 100% safe ?

Regarding the ESD fix, is it related to proper grounding of the chassis ? With a meter It seems that the chassis (using one of the metal screws) is connected to the signal ground.

Gave it a listen with HD650 and it sounds perfect to me, as the objective measurements suggest. It replaces my extremely bulky dual-chassis AMB M3 that I built a few years ago. That should be a high-performance amp as well (don't have the opportunity to perform any reliable measurement on it) but the amount of space and weight it takes up is something like 30 times the little L30. With heat and power consumption that matches its size, thanks to the overkill class A mosfet output stage. From a purely subjective standpoint it's hard to tell any difference between the two (it's very hard to A/B amps). Probably both are almost transparent and quite close to a piece of wire with gain for the HD650 that has no particularly special power requirements. Given the stellar measurements, the L30 should be much closer to perfection...
 

half_dog

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thanks, so as an example my ifi Zen Can can run quite happily at full power with 2v in, so is this just a different design as many Amps mid and upwards do not rely on the DAC input power to reach their full potential.
Actually it relies on the input signal but 2V(even a little less) is enough to it reaches its maximum power output - considering the saturation point. That's about gain...
 

Jave

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@JohnYang1997 - I recently received my L30 replacement and the volume pot has a little give. I can move it from side to side without changing the volume, like it doesn't sit well. How can I fix it?
 

solderdude

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Is it caused by the potmeter not being fixed against the frontplate or just a little too loose ?
Is it caused by some slack between the knob and potmeter shaft ?
Is it caused by the potmeter shaft too loose in the potmeter enclosure ?

Maybe some DIY fix is possible ?
 

JohnYang1997

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Is it caused by the potmeter not being fixed against the frontplate or just a little too loose ?
Is it caused by some slack between the knob and potmeter shaft ?
Is it caused by the potmeter shaft too loose in the potmeter enclosure ?

Maybe some DIY fix is possible ?
The total offset distance across 4 gangs.

Not DIY fixable.
 

Robbo99999

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@JohnYang1997 - I recently received my L30 replacement and the volume pot has a little give. I can move it from side to side without changing the volume, like it doesn't sit well. How can I fix it?
What you complaining about, my knob literally just fell off my JDS Labs Atom! :p Well actually, I could just push it back on again (for my JDS Atom it's just the plastic knob loose on the shaft...well not loose per say, just it can pull on & off quite easy).
 
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TheBatsEar

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So, i have a unit with the ESD issue, bought privately, so i can't give it back. :oops:

I have seen that there is a pogo pin that connects ground to the case in the fixed units, would that be all? If not, what else needs to be done?
 

Atanasi

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So, i have a unit with the ESD issue, bought privately, so i can't give it back. :oops:
Check if the unit was replaced. If you were sold a unit that was supposed to be destroyed, it was fraud.
 

TheBatsEar

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Check if the unit was replaced. If you were sold a unit that was supposed to be destroyed, it was fraud.

It's like someone asking how to fix a slashed tire, only to receive a speech that it is illegal to slash tires. I know i have made a mistake here and someone took advantage. My question wasn't about the legal ramifications, I want to fix it.

I have seen that there is a pogo pin that connects ground to the case in the fixed units, would that be all to fix the ESD issue? If not, what else needs to be done?
 

solderdude

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So, i have a unit with the ESD issue, bought privately, so i can't give it back. :oops:

I have seen that there is a pogo pin that connects ground to the case in the fixed units, would that be all? If not, what else needs to be done?

depends on the serial number.

To fix the DC protection itself requires changes on the PCB (layout and components) and in firmware (you can't get) so you can really only prevent ESD to blow something up inside but the DC protection still won't work properly.

So if you are willing to risk damaging your headphones keep using it.
You'll just remove the chance it is caused by ESD by connecting the enclosure to signal ground.
It could be your headphone's funeral.
 

TheBatsEar

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To fix the DC protection itself requires changes on the PCB (layout and components) and in firmware (you can't get) so you can really only prevent ESD to blow something up inside but the DC protection still won't work properly.

Who told you that there is a need for firmware changes?

What changes to the PCB are needed?

So if you are willing to risk damaging your headphones keep using it.

I don't. I want to fix the issue. Thought i made that clear, but should have done a better job obviously. So far i didn't turn it on at all.
 
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