Lepai T-Amp with TA2020

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kroem

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Joined 2011
sofaspud said:
You can get a better power supply. Something like 13.5V/4A to replace the included 12V/2A. And/or you can try to keep the chip cooler. Honestly, though, I can't imagine why anyone would want to listen to a max'd out Lepai... It's just a "small, economical, get-around-town" amp, not a "take to the track and rev it up" amp.
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Na, but I'd like to keep it somewhere in the middle ;) I run it of a 8-pack of D-cells, so could be a power issue...
 
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Anteaus

Member
Joined 2011
sofaspud said:
I can't imagine why anyone would want to listen to a max'd out Lepai...
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The TA2020 driving 2x 4ohm loads to clipping will take a peak current of over 6A, so even with music duty-cycles, a 2A supply is going to be a bit stretched at full volume. 3/4A would be more suitable.

Though, a module sporting a pair of the 100W chips would be better for serious bass.
 
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K

kroem

Member
Joined 2011
Anteaus said:
The TA2020 driving 2x 4ohm loads will take a peak current of 6A, so even with music duty-cycles, a 2A supply will max-out long before the Lepai does. (You will soon know, because the LED dims)

Though, a module sporting a pair of the 100W chips would be better for serious bass.
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So... I'd be able to "identify" this if the LED dims when the music chops?

I would prefer a little more W, but I have it all in a suitcase so...
 
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pkozul

Member
Joined 2011
Hi there,

Just a question about the volume and bass/treble pots.

I would like to find some replacements for the stock pots on the Lepai but I’m not sure which ones I need to get.

I have removed them and noticed that the volume pot is B50K and the bass/treble pots are B100K.

When buying these new pots, what do I need to look out for? From what I have read in other posts, they should be logarithmic (which I think the ‘B’ stands for). Should the replacement volume pot be 50K or 100K? Also, what size is needed? I have seen various sizes like 9mm, 16mm, 24mm, etc.

Thanks!
Pete
 
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lossfound

Member
Joined 2007
I bought a handful of these things to experiment with and, being a longtime TA2024 / TA2020 fan, I am sorely disappointed. They run out of juice and start clipping much too early, way earlier than any of my other T-amps. Tested all of the amps I got on four different and moderately-to-incredibly efficient pairs of speakers with similar results.

I am guessing the wimpy 12V/2A power supply is to blame in large part-- my other TA2020 amps came with somewhat beefier PSes and are obviously much happier for it. I don't want to do a lot of modding or PS building... does anyone have a good cheap recommendation for a cheap aftermarket laptop brick that will bring these things a little closer to their actual potential?
 
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nige8388

Member
Joined 2009
lossfound said:
I bought a handful of these things to experiment with and, being a longtime TA2024 / TA2020 fan, I am sorely disappointed. They run out of juice and start clipping much too early, way earlier than any of my other T-amps. Tested all of the amps I got on four different and moderately-to-incredibly efficient pairs of speakers with similar results.

I am guessing the wimpy 12V/2A power supply is to blame in large part-- my other TA2020 amps came with somewhat beefier PSes and are obviously much happier for it. I don't want to do a lot of modding or PS building... does anyone have a good cheap recommendation for a cheap aftermarket laptop brick that will bring these things a little closer to their actual potential?
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This should do the trick, 12V 6A Located in Utah ($11 Shipped):

NEW 12V 6A 72W AC POWER SUPPLY ADAPTER FOR LCD MONITOR | eBay


Nicholas
 
K

kristleifur

Member
Joined 2006
lossfound said:
Cool, Nicholas, I will give that one a go. I wonder if the amp might also benefit from a voltage increase, although I also don't know if there's anything particular about the Lepai board that would make this a bad idea.
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That I know of, only capacitor tolerances would be a limiting factor. (Besides the heatsinking capacity ...) Actually, it seems to be quite hard to find capacitors that work in these amps and that DON'T allow for the rail voltage to be increased to the chip max of about 14.5V. So it should be OK.

Also, IIRC the chip starts to strain at above 13V or so into 3 Ohm loads.
 
gychang

gychang

Member
Joined 2005
lossfound said:
Cool, Nicholas, I will give that one a go. I wonder if the amp might also benefit from a voltage increase, although I also don't know if there's anything particular about the Lepai board that would make this a bad idea.
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I noticed the ebay item may not come with the cable on the AC side... I have heard maximal is 13.5V but not sure how much Lepai can handle.
 
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Anteaus

Member
Joined 2011
You can get some 15v, 4/5A laptop PSUs on Ebay, very cheap. The Toshiba-replacement ones seem to be the highest rated. 15v is pushing thngs a bit with a TA2020 and 4ohm speakers, although you can reduce it to more like 13.6 by putting two power diodes in series.

2A is adequate for 8ohm loads but definitely not enough for two channels loaded with 4ohms.

Also worth noting that with a beefy PSU or above-spec voltage the TA2020 will not tolerate output shorts, so make sure your speaker wiring is reliable.
 
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lossfound

Member
Joined 2007
OK, I pulled the 12V / 5A supply that came with my Muses and did a little A/Bing yesterday with the Lepai, pulling a 4-ohm load. I have a demo track with a low, filtered "heartbeat" bass drum which, in initial testing, was particularly good at causing the Lepai to spit and sputter most audibly and violently. Using the stock 2A supply I brought the Lepai's volume knob *barely* up to the point where the bass drum caused clipping (right around 12.5 o'clock) and shut 'er down, switching to the 5A and turning things back on with all other variables held constant. The clipping was no better. I found the same to be true in more typical music... as soon as the 2A started clipping out, I'd shut the amp down and switch over to the 5A with no improvement.

Between this behavior and the incredibly loud hissing produced with a load (any load!) attached to the RCA jacks on all of these amps, I wonder if the problem is actually the EQ / gain circuit in the Lepai rather than the power amp section.
 
gychang

gychang

Member
Joined 2005
lossfound said:
OK, I pulled the 12V / 5A supply that came with my Muses and did a little A/Bing yesterday with the Lepai, pulling a 4-ohm load. I have a demo track with a low, filtered "heartbeat" bass drum which, in initial testing, was particularly good at causing the Lepai to spit and sputter most audibly and violently. Using the stock 2A supply I brought the Lepai's volume knob *barely* up to the point where the bass drum caused clipping (right around 12.5 o'clock) and shut 'er down, switching to the 5A and turning things back on with all other variables held constant. The clipping was no better. I found the same to be true in more typical music... as soon as the 2A started clipping out, I'd shut the amp down and switch over to the 5A with no improvement.

Between this behavior and the incredibly loud hissing produced with a load (any load!) attached to the RCA jacks on all of these amps, I wonder if the problem is actually the EQ / gain circuit in the Lepai rather than the power amp section.
Click to expand...

thanks for the test, at least high Amp rating does not seem to do much.
 
sofaspud

sofaspud

Member
Joined 2005
Is this the LP-2020A+ being tested?
Several people have mentioned experiencing a noticeable lack of low frequency power out of these things. Everyone seems to want bigger coupling capacitors, but it might be that there are cases where a higher LF cutoff will give better overall results.
You'll have to explain attaching a load to the RCA jacks.
 
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lossfound

Member
Joined 2007
When I say "load," I simply mean that there is an inordinate amount of hiss and noise when a device is connected to the RCAs. I've noticed this driving the Lepais with my phone, my laptop, and a turntable running through a very nice recent-era McIntosh preamp that was sitting around the shop. I have not tested the 1/8" in yet to see if the symptoms persist, but when the RCAs are disconnected, the white noise stops.

Also, I have no complaints about the lack of low end, at least through certain speakers I've tried (though they did sound unusually tin-canny through a set of Altec 604s). If anything the low kick drum test I used indicates that the amps are working far too hard to produce the lower end of the spectrum.
 
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xoaphexox

Member
Joined 2008
Received my TA2020(A+) from Parts Express a few days ago.

Recapped using Panasonic FM/FR for the power supply electrolytics and Elna Silmic II for most signal path electrolytics. Also replacing the output film caps with polypropylene caps.

I am not comfortable with removing the SMDs but I was thinking about replacing the stock 10uH inductors.

Has anyone tried this on the new model yet? I think it sounds better in tone bypass mode than with tone controls in circuit - things sound a bit muddy and veiled - thinking this may be the stock 1.75uF electrolytics I left in circuit - I was going to try a pair of Nichicon Muse ES Bipolars here, 2.2uF - or 1uF depending on what sounds best.

Anyone try that either?

Thanks!
 
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