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Topping L30 Headphone Amplifier Review

Iglo

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I got my L30 replacement yesterday and at first I was happy, hooked up my headphones and sound was great both from my laptop via USB and TV via optical to E30 to L30 to headphones.

Today I can't get it to work. The only difference is that I set up the APO Equalizer on the laptop. I can get sound from my speakers if I disconnect the L30 and go directly from E30 to my preamp. However from L30 I cannot get any sound (E30 in DAC mode) via headphone output or through my speakers in PRE mode. Tried 3 different RCA cable pairs between the E30 and L30 too. Tried my laptop via USB and TV via optical like yesterday. Anything I'm missing?

Just to check all options, could you try the L30 with another source (so maybe laptop > amp) without the E30? And if the status led on?
Third thing that comes to mind; do you hear the relays click when you change the front switches (OFF / HPA / PRE)?
 

imnotdrunk

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Just to check all options, could you try the L30 with another source (so maybe laptop > amp) without the E30? And if the status led on?
Third thing that comes to mind; do you hear the relays click when you change the front switches (OFF / HPA / PRE)?
I swear I checked all the connections, but something must have been loose since now it is working again! :)
It's almost always user error, especially with me....
 

Iglo

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I swear I checked all the connections, but something must have been loose since now it is working again! :)
It's almost always user error, especially with me....

Glad to hear everything is working again!
 

Bsdzilla

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Glad to see they've permanently stopped the practice of removing the text from the components. I'm a firm right-to-repair believer and that stupid sanding of IC's will only hinder the repair-people and hardly deter the copy-people. They stopped doing that much earlier than this new revision, by the the way. Now you're only truly f*cked if the STM microcontroller quits, since they don't open source the firmware. But some relay, delay and dc-protection logic could also be reverse engineered, so there's hardly any ground to keep that a secret also.
 

audiojoe

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Just got my replacement from Shenzhenaudio and it is a 2101... model. Only small differences I could notice about the build from the outside, for example a much less stiff volume knob (not that it was any bad before of course) and an ever so slightly rougher feeling texture on the shell. Other than that everything seems the same and I am very happy with Topping and Shenzhenaudio^^ There was that annoying issue with their customer support not being able to get into contact with the amazon seller department, (which is apparently seperate) but thanks to the instructions by @GGroch (thank you again!) I got through the rather hidden option on Amazon and everything went smoothly from there!
 

Acerun

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I just got a serial number beginning with 2101... I'm guessing that's good and one of the newest ones, correct?
 

dgnzcn

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Isn't the noise of the TL072 less than that of the NE5532?
Why should it be at a disadvantage?
 

dgnzcn

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The NE5532 is far superior to the TLO72 in just about every way for audio use, only real exception being the 5532s' relatively large input current spec. The TLO72 has a very limited ability to drive a load, it's prone to latch up if the inputs are overloaded, and has many other "features" that make it undesirable for audio in my opinion.

https://www.diyaudio.com/forums/analog-line-level/253155-tl072-vs-ne5532.html

Are these explanations correct?
If it is correct, why was it replaced with a lower quality chip?
 

Veri

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The NE5532 is far superior to the TLO72 in just about every way for audio use, only real exception being the 5532s' relatively large input current spec. The TLO72 has a very limited ability to drive a load, it's prone to latch up if the inputs are overloaded, and has many other "features" that make it undesirable for audio in my opinion.

https://www.diyaudio.com/forums/analog-line-level/253155-tl072-vs-ne5532.html

Are these explanations correct?
If it is correct, why was it replaced with a lower quality chip?
:rolleyes::rolleyes: This opamp is part of the ESD/static discharge protection. If the protection works it works. Get it?
 

dgnzcn

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NE5532 vs TL072

TL072 is also a very popular op amp, which often used to compare with NE5532, trying to know which one of them is quieter.

Well, the NE5532's bipolar transistor inputs draw input current and are not the same as the TL072's JFET inputs, which have no input current. As a result, if the source impedance is extremely low (specified at 20 ohms), the NE5532 is three times quieter.

However, when the source impedance is around 18.5k ohms, they have equal noise levels because the input current noise adds to the NE5532's input voltage noise. The TL072 is quieter when the source impedance is greater than about 18.5k. A NE5532 is frequently seen as a phonograph cartridge, tape head, or microphone preamp with a massive input coupling capacitor that takes nearly forever to charge. The large input cap's low impedance keeps the input current noise to a minimum.


The NE5532, which has bipolar transistors on its input, has "popcorn" noise below 30Hz, whereas the TL072 has much less.


The NE5532 has back-to-back protection diodes on its inputs that cause many circuits to fail, and it consumes significantly more supply current than a TL072.

https://www.apogeeweb.net/circuitry/NE5532-comparisons.html



I understand the TL072 is more suitable for safe and quality sound, correct if I'm wrong please?
 

solderdude

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The NE5532 is not in the audio path.
It just works as a level detector.
It is completely irrelevant what the used quality is as long as it functions as it should.
 

somebodyelse

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:rolleyes::rolleyes: This opamp is part of the ESD/static discharge protection. If the protection works it works. Get it?
You mean the DC offset detection/protection don't you? In either case it's not in the audio path and its audio qualities are irrelevant in this use.
 

Veri

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You mean the DC offset detection/protection don't you? In either case it's not in the audio path and its audio qualities are irrelevant in this use.
Yep, as solderdude cleared up just now. I'd trust in his expertise ;)
 

liu

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5532 was a wrong choice because it has a rich feature set -- it will shutdown itself when things are wrong, such as overvoltage.
this is bad for dc dection --- the op amp shut itself off and never notify the microcontroller that something goes wrong.
 
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