Good when genuine. V shaped sound with accurate midrange.
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Topping L30 Headphone Amplifier Review
- Thread starter amirm
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The Amp has a relative higher PS noise compared to its noise floor.
Here's the 50mv test (more real world than full volume test, as people may normally use that volume as full volume).
the final thd+n does reach the -94db in amirm's test. So I'm measuring it correctly as he did.
On the left hand side you'll see two spikes around 50hz (PS frequency at my country), which is just -104db lower than main tone.
The noise could be audible when listening quiet passages of your music with high dynamics (such as classical) with a regular listening volume (50mv as full amplitude ).
Pretty sure the PS main noise come from the Amp, rather than DAC (a topping E30), as turning either digital volume of the DAC or analog volume of the amp does not change the noise amplitude -- it just stay there, unless I plug in the DAC directly sans the Amp.
Here's the 50mv test (more real world than full volume test, as people may normally use that volume as full volume).
the final thd+n does reach the -94db in amirm's test. So I'm measuring it correctly as he did.
On the left hand side you'll see two spikes around 50hz (PS frequency at my country), which is just -104db lower than main tone.
The noise could be audible when listening quiet passages of your music with high dynamics (such as classical) with a regular listening volume (50mv as full amplitude ).
Pretty sure the PS main noise come from the Amp, rather than DAC (a topping E30), as turning either digital volume of the DAC or analog volume of the amp does not change the noise amplitude -- it just stay there, unless I plug in the DAC directly sans the Amp.
All the mains related noise are either from your source or are picked up by the RCA cable or other components in your measurement setup. The mains noise measured using APx555B is typically at 60nV, max under 100nV. This is so far the best ever PS noise performance from any single ended devices that I know(except for battery powered)
With aid of external preamplifier the 50mV SNR is measure over 104dB no weighting. Confirmed by Wolf's measurements.https://www.audiosciencereview.com/...asurement-of-topping-l30-headphone-amp.14252/
In your case it can come from E30's power supply, from USB if that's what you use, from the ADC you are using or any wiring in the loop.
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> All the mains related noise are either from your source or are picked up by the RCA cable or other components in your measurement setup.
All other things are battery powered. Cables are already short enough --- I specifically used 10cm cables.
> Confirmed by Wolf's measurements.https://www.audiosciencereview.com/...asurement-of-topping-l30-headphone-amp.14252/
Wolf's measurements confirmed most of the -104db noise come from the PS tone rather than random one.
His 4V FFT shows 145 PS noise at 200Hz. at 50mv the main tone is 145- log((4/0.05)^2)/log(2)*3 = 145- 38 = 107db higher than PS tone.
All other things are battery powered. Cables are already short enough --- I specifically used 10cm cables.
> Confirmed by Wolf's measurements.https://www.audiosciencereview.com/...asurement-of-topping-l30-headphone-amp.14252/
Wolf's measurements confirmed most of the -104db noise come from the PS tone rather than random one.
His 4V FFT shows 145 PS noise at 200Hz. at 50mv the main tone is 145- log((4/0.05)^2)/log(2)*3 = 145- 38 = 107db higher than PS tone.
well I can measure it, I can hear it, that all. My setup is already more controlled than most people's, with super short 10cm well isolated rca cable, and battery powered E30 and laptop (relies on its own battery). the only thing connected to the power cord is this amp.
Or it's -150dB ref to 2V in Amir's measurement. Equals to 0.064uV or 64nV.
yea. I see amirm's test it's a lot better, even with lower output full amplitude than Wolf's.
My PS noise is similar to Wolf's. His spike (-145db) is lower in the FFT because full amplitude is 4V.
His test is even worse as the noise is at 200Hz, so should be more audible than mine.
I think some of the graphs are from using the previous power supply. And there's absolutely no way at this level it's audible. If you think your power supply is faulty you may contact seller and try a new one. That's all I can say because this is one of the most important aspects in the design.
As @JohnYang1997 said good when genuine.But it is a lottery, its sound can vary considerably. I have two units with me right now and have tested other two. 2 were bought from Samsung online store (at the same order), one came with my Galaxy S9 and the last were from a S8. The unit from S9 and one from Samsung's store sounds very similar (a little less bass, but keeping the sub bass and more piercing treble - quite annoying). The other unit from Samsung has the best sound - just as before, but less treble. S8's unit has a lot of bass and a little less of treble.
Jave
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And how would you get rid of such a loop?
There are methods to search for and fix it . Have you search it even a little ?
Loop only exists when you measure things. The headphone is open end essentially.
Look, compared to Atom, this is 30dB of improvement in PS noise. It's because at this level such things become measurable differences. In no way in real world this is gonna matter. Of course reducing such noise to lowest level reduces chance of the issue happening or completely get the issue out of the way from the amp itself.
solderdude
Grand Contributor
Indeed, the only possible loop is mains power supply to RCA in.
Currents in that loop may result in 'hum' in the signal.
The chosen transformer will increase this loop resistance's path for low frequencies much more than the average and perhaps even medical grade SMPS resistance at least for audible frequencies. For higher frequencies (MHz), due to capacitive coupling, depending on how the transformer is constructed, this may not differ that much.
When measuring the amp the in and output path have the same ground (plane) and forms a loop which does not exist in real world situations.
Currents in that loop may result in 'hum' in the signal.
The chosen transformer will increase this loop resistance's path for low frequencies much more than the average and perhaps even medical grade SMPS resistance at least for audible frequencies. For higher frequencies (MHz), due to capacitive coupling, depending on how the transformer is constructed, this may not differ that much.
When measuring the amp the in and output path have the same ground (plane) and forms a loop which does not exist in real world situations.
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As soon as I got the notification from them instantly ordered L30+E30. Now I just have to wait so more days.
Okay, there is one thing that's annoying and it isn't L30 (serial 2005) exclusive - same on E30 (serial 2003). The RCAs connectors have a smaller diameter than usual making almost all my cables being kind a loose cutting the signal. There is another E30 (serial 2006) here and the fitting is okay, did Topping realize this and replaced the connectors?
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