Lepai Tripath LP-2020A+ mini Amp dissected

Discussion in 'DIY' started by Gary Indiana, Aug 23, 2012.

  1. Gary Indiana

    Gary Indiana Active Member

    Here is my new Lepai Tripath amp. What makes these amps attractive is their tiny size, high efficiency, very decent sound quality, and more than affordable price.

    I bought my first Lepai amp a couple of years ago on ebay for about $25 shipped from China. The one and only thing I did not like about it then was loud pop in the speakers when powering ON and OFF.

    New Lepai amps are upgraded with speaker relay that delays their connection until the circuitry is stable and no DC present on the outputs. There is still a little pop when turning the amp OFF, but that should be taken care of with an upgraded, larger filtering cap.

    These amps are currently offered on Amazon for $20 shipped with a 12V 2A switched power supply. There is consensus among users that the power supply should deliver 4 to 5 Amps for the Lepai to kick some diaphragm. And so a better power supply should be put on the top of the list of upgrades. I got my good used 12V 5A power supply at local Goodwill for $1.99.

    Second important IMO upgrade would be replacement of the filtering capacitor for a more beefy one. Ideally the 16V cap should be 4700uF or more if dimensions allow fitting it inside the case: the more uF - the better. The cap it came with originally is a measly 2200uF. I think this causes the slight pop in speakers since it discharges too quickly, before the relay turns OFF speakers. Bigger supply cap should also help with bass.

    The blue LEDs don't tickle my fancy especially, so I replaced these with a pair of warm white LEDs, which resemble the glow of a light bulb. It looks better IMO.

    As I'm posting this, my $20 Lepai pumps delightful jazz from a Chesky CD in my NAD C541 to a pair of Mission 773 towers. This "audiophile" setup cost me less than $100 thanks to Craigslist and Goodwill. :D

    And so, here it is.

    Comes nicely packed in a foamy cutout with a small 12V 2A switched power supply.


    That's what it looks like inside. Tidy, tidy, tidy.


    The black square relay is an upgrade to older design; meant to protect speakers from loud pops.


    The Tripath TA2020 chip is the heart and soul of the little amp. Thanks to its great efficiency of 80% to 90% it does not require large heatsink.


    This is the underbelly of the beast. Again: a tidy PCB design.


    The PCB - printed circuit board - is made of decently thick double-sided copper clad fiberglass. It doesn't get much better than that.


    Here is a bird's-eye view.


    This one capacitor shall be upgraded soon.


    Blue LEDs inside…


    …and their original blue glow around the knob outside.


    Warm white LEDs replaced the blue pair.


    This "upgraded" look is better, IMO.

    Last edited: Jul 11, 2014
  2. tdx1

    tdx1 New Member

    These little amps make great test beds for mods, I'd probably recap the whole thing since I'm not a fan of a lot of the questionable caps found in these things. I'm not certain it would dramatically improve the sound, but from a reliability standpoint caps are the biggest failure point of nearly any electronics these days. Good call on the LED swap, blue is way too overdone on electronics now and is believed to cause retina degradation.
  3. Ohighway

    Ohighway AK Subscriber Subscriber

    Thanks for the pix and the info !
  4. mhardy6647

    mhardy6647 AK Subscriber Subscriber

    A remarkable sound value per dollar no matter how you look at it.
    I - ultimately, and tentatively - tried mine on the Duplexes and I was very surprised by how well it acquitted itself.
  5. Gary Indiana

    Gary Indiana Active Member

    IMHO the cap in near power supply jack could use more capacity, but I'd leave the rest as is. Radical cap replacement could cost more than the amp itself but without a noticeable sound improvement.
    The first mass produced LEDs were red in 1968 soon followed by yellow and green, while blue LEDs were first factory made much later - in 1989. Perhaps now some try to over-compensate for the two decades without blue. ;)
    You're welcome!
    It's a poor man's McIntosh ;)
  6. Redboy

    Redboy a few good watts Subscriber

    Every now and then, I see something like this and I wonder why I bother to build tube amps, given the cost and overall quality of stuff like this!
  7. 68custom

    68custom AK Subscriber Subscriber

  8. mhardy6647

    mhardy6647 AK Subscriber Subscriber

    Your (erstwhile) handcrafted Simple 2A3 does sound better than the Lepai, buddy! The latter is a little zingy in the HF compared to the former.
  9. mfhale

    mfhale AK Subscriber Subscriber

    Apples and cumquats, Nate.
  10. Rick Vestal

    Rick Vestal Have a nice day and duck!

    This is yet another example... I have trouble looking at everything that goes into that, and believing it's only $20. Same with those $0.99 strings of Christmas lights at WalMart...
  11. mhardy6647

    mhardy6647 AK Subscriber Subscriber

    Hourly labor costs are probably a little different where it was made compared to what you are used to.
  12. Ballylongford

    Ballylongford AK Subscriber Subscriber

    Got one of the much vaunted Arjen Helder DIY amps from his eBay store recently, and one of these same Lepai units.

    The Arjen Helder unit shuts down on its own and he has refused to stand behind it.

    The Lepai sounds great (definitely sounds better w/ the more robust aftermarket power supply I am running it w/), and is very reliable.

    From what I have read of the quality issues w/ the earlier Lepai units there seems to have been improvement.

    Hard to beat for the price.
  13. OJNeg

    OJNeg New Member

    Nice job! :thmbsp:

    Have you tried testing the power output yet? I know that Lepai rates the amp for 12W into a 8 ohm load, but I've seen some tests where it only puts out something like 1.5W (into an 8 ohm load) before reaching 1% distortion and it clipped not too far after that. I know personally that I was able to get my TA2020+ to clip easily into a pair of inefficient bookshelves. I'd like to see if it performs any better running off a beefier power supply.
  14. Gary Indiana

    Gary Indiana Active Member

    Yes, I am running it on a bigger power supply and there is an improvement. In the picture below there is the wallwart that came with the amp: 12V, 2000mA (=2A), next to one I use now, picked used at GW store for $2, rated 12V, 4.58A. The bigger one, wherever it came from originally, is heavier and, likely, much better quality with the barcode and serial number on it. Cheap adapters don't have serial numbers.

    With the bigger supply I'd need to crank up the volume way higher before getting distortions and clipping. From what I'm hearing I'd say the max. undistorted volume could be compared to a "normal" amp rated 2x20 Watts, or be very close to it.

    EDIT: Someone did proper bench tests of this amp and posted results on youtube.

    Last edited: Jul 11, 2014
  15. Hat Alto

    Hat Alto Active Member

    Thanks for posting this very good Lepai 2020a+ thread. LED mod = instant improvement in class. Ordered one last night. I'll go GW for a power supply as you suggest and probably swap those two caps - and maybe shoot the case with some blk spray to cover up some of that ugh labeling. I mean $20 - come on!
  16. dumptruck

    dumptruck AK Subscriber Subscriber

    I'd love to see a Redboy Hypex NC400 amp. :D
  17. 1MOR

    1MOR AK Subscriber Subscriber

    Parts Express also sells these.


    I did a rebuild, replacing the through the hole parts with Pany, Nichicon, Epcos caps and upgrading the inductors. PS is a 12V 5A model from ebay. The improvement is significant. Yeah, I understand this is a $20 amp, but after all, this is DIY.

    Attached Files:

  18. calrec

    calrec New Member

    How much higher than 4700uf can the filter capacitor be? Is it necessary to up the voltage to 25v also?
  19. 1MOR

    1MOR AK Subscriber Subscriber

    How much higher? You want it to fit on the board, and still fit into the case. so you could probably go to 5600uf. Why 25 volts? Its what Mouser had when I ordered.

    The caps that came installed in this amp left quite a little to be desired quality wise. I measured most after I removed them. Some were way out of spec and most had significant differences, same value cap when used in both channels.

    Here is the thread that put me onto Lepai amps, its over on the Parts-Express website, TechTalk

  20. Binkman

    Binkman AK Subscriber Subscriber

    IMO the OP sounds more like a sales pitch w/extensive photo's. then replace caps and power supply? 0.1% distortion? You get what you pay for.

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