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Old 22nd July 2013, 03:17 AM   #1621
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Quote:
Originally Posted by KopiOkaya View Post
For significant improvement to the Lepai, a friend of mine, armed with the right tool, managed to desolder the stock surface-mounted JRC 4558D opamp and replaced with a LM4562 with very good results.
Other than a bigger linear supply, this is the only mod to my Lepai. It's the LP-2020A+ with the blue PCB. I have no before & after measurements, so it's nice to see others having success replacing the op amps. I discussed it some back in post #842 and post #1147.
It's not a difficult mod. It can be accomplished with soldering iron, X-acto utility knife, solder wick, and a bit of patience while working.
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Old 22nd July 2013, 08:09 AM   #1622
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Originally Posted by sofaspud View Post
I have no before & after measurements, so it's nice to see others having success replacing the op amps.
Yeah... My friend did ran into some distortion problem after the opamp upgrade but miraculously, the distortion disappeared after a while. One thing for sure, a bigger power supply is a must after the upgrade.
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Old 23rd July 2013, 07:40 PM   #1623
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Originally Posted by KopiOkaya View Post
[snip]
Personally, I don't think changing the heatsink or reapplying the heatsink compound makes any difference. After all, the Tripath TA2020 runs cooler than most Class AB chipsets (some Class AB amps doesn't even utilized a heatsink!). I won't go the extra mile if the tweak doesn't improve sound quality. [/snip]
I agree, but it's 10 minutes work, and you never know - you might end up thrashing the chip to within an inch of it's life for hours at a time (as I might if I use it to drive a passive sub), and it might extend its life a little, so why not?!

Last edited by Aleksunder; 23rd July 2013 at 07:44 PM.
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Old 23rd July 2013, 09:04 PM   #1624
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Quote:
Originally Posted by KopiOkaya
For significant improvement to the Lepai, a friend of mine, armed with the right tool, managed to desolder the stock surface-mounted JRC 4558D opamp and replaced with a LM4562 with very good results.
Quote:
Originally Posted by sofaspud View Post
Other than a bigger linear supply, this is the only mod to my Lepai. It's the LP-2020A+ with the blue PCB. I have no before & after measurements, so it's nice to see others having success replacing the op amps. I discussed it some back in post #842 and post #1147.
It's not a difficult mod. It can be accomplished with soldering iron, X-acto utility knife, solder wick, and a bit of patience while working.
Thanks for taking the trouble to reference these earlier Lepai opamp mod posts - it keeps this HUGE thread useful.
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Old 25th July 2013, 08:31 PM   #1625
lsheng is offline lsheng  United States
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Default consider avoiding these inductors

See the blue inductors, those ones are not good. If you do not connect amplifier to speaker, just play some music, you can hear those inductor making sound, which is a bad indicator for extra nonlinearity. I replaced them and the sound improved.



Quote:
Originally Posted by KopiOkaya View Post
Those of you who are not good with soldering and assembling but prefer a high quality Tripath TA2020 amp can consider the SMSL SA-36A.

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Old 25th July 2013, 09:22 PM   #1626
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Not to get too off topic but do you know if there is any common consensus about the inductors used in this YuanJing board with a TA2020.

They seem to sound better than the ones that came installed in the LePai TA2020A+ that I have, but I wonder where they fall in the list of inductors from worse to best.

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Old 26th July 2013, 12:40 PM   #1627
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Originally Posted by lsheng View Post
See the blue inductors, those ones are not good....
According to SMSL specs, those blue ones are TDK inductors. I thought TDK makes some of the better inductors.

Last edited by KopiOkaya; 26th July 2013 at 12:45 PM.
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Old 1st August 2013, 09:29 PM   #1628
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Default Lepai tone-defeat reverses output phase!

I've set up the Lepai and Indeed TA2020's together. Input is looped through the Lepai on to the Indeed.

The Indeed is driving Wharfedale DIamond 9.0's, the Lepai a 20 year old JPW passive sub.

The JPW sub is 12 ohms, intended to be connected to 8 ohm speakers such as JPW mini-monitors (obviously), which are 8 ohm. The paralleled loads would give c. 6 ohms, but the Lepai is only seeing the 12 ohm load, hence it can probably manage about 5-6 clean watts per channel into it.

The JPW actually has label on it which declares that its senstivity is 95dB/watt at 1 metre, for what that's worth.

Setting up, I had to determine phase. I tried music and bass test tones - listening at various positions in the room, then shutting down and reversing the speaker connections on the JPW, very laborious and inconclusive. I just left them both connected the same way round (which happens to be with all speaker connections reversed - I gather tripaths invert).

BUT!!! Discovered that the tone circuit reverses the output phase!

Despite they're dropping overall level, when I enabled the tone controls (set at flat), the in-room bass levels jumped substantially.

So there you have it - a very useful feature of the Lepai is that the tone-defeat doubles up as an output phase switch!

So far, so very impressive. I just listened all the way through Air's "Talkie Walkie", and it was like some-one had shaken me awake when it ended.

ETA >> the Lepai reverses channels on its 3.5 input jack, easily fixed by swapping its RCA inputs around.

Last edited by Aleksunder; 1st August 2013 at 09:45 PM.
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Old 1st August 2013, 11:32 PM   #1629
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Quote:
Originally Posted by Aleksunder View Post
BUT!!! Discovered that the tone circuit reverses the output phase!

So there you have it - a very useful feature of the Lepai is that the tone-defeat doubles up as an output phase switch!
Well done! Great discovery.

Last edited by KopiOkaya; 1st August 2013 at 11:36 PM.
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Old 1st August 2013, 11:59 PM   #1630
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I guess that the total phase difference at the speaker-coils of the two amp/speaker combos (lepai/JPW, Indeed/Warfhedales) could have ended up anywhere from 0 to 180 degrees, and if it happened to be 90, then reversing the phase of either would make no difference.
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