Lepai T-Amp with TA2020 - Page 21

e_fortier · 25th April 2009, 12:03 AM

Hi,

At $25 USD + shipping I coudn't resist so I bought the newer version (TA2020-020 v3.1) last night from Export-Genie on e-bay.

Did anyone came out with a list of mods yet ?

Cheers,
Eric

e_fortier · 25th April 2009, 12:11 AM

Me again

By looking at the pics it looks like (I do not have mine yet) they have put a 14V Zener at the DC inlet, this is a neet idea.

Anyhow, maybe someone can confirm this.

Eric

JWFokker · 26th April 2009, 01:07 AM

I just ordered one of these today. I guess T-Amps don't generate much buzz these days because this thread is the only discussion of the Lepai amps that I've come across, in English at least.

col · 27th April 2009, 07:13 AM

just ordered one too.

col.

Gmorris · 27th April 2009, 08:09 PM

The amp arrived today. I hope to plug it in later tonight.

Now I just need some solar panels to trickle charge my SLA battery.

Gmorris · 28th April 2009, 02:23 PM

The little amp seems to work as it should. I still haven't had time for much listening. I did remove the op-amp and replace it with a socketed LM4562. I could only hear low-level hiss from my tweeters if I had my ear within an inch or two from them. There was also audible low-level hum (not noticable from more than a foot away) if I touched the case. DC on the output was around 55 mV. There was some turn-off thump but not too bad. The power button does not affect the blue LED....it stays on as long as the power supply is connected.

I also noticed that the two small electrolytics closest to the volume pot appear to be the input caps. Positive goes from input to the pot to the caps. These caps were labeled 2.2uF on the board but 10uF on the caps. Also, a 47uF cap between the opamp and the tripath chip (next to the heatsink) was labeled 100uF on the board.

Overall, it seems to be a great deal. And I like the metal case better than the plastic SI / Dayton amp...

JWFokker · 28th April 2009, 03:02 PM

Well, if I remember correctly the SI T-Amp had a "floating" ground, which is part of the reason why they used a plastic enclosure, but that used a TA2024 instead of a TA2020, so I don't know if it's directly comparable. But it would seem to me that it probably shouldn't be grounded to the case, even though it is.

Also, can the DC at the output be remedied with a small cap across the terminals like on the SI T-Amp?

Gmorris · 28th April 2009, 04:03 PM

55mV dc offset would be pushing it for a headphone amp but I don't think it's too bad for speakers. Dunno about the cap across the terminals...

The board seems to be attached to the case through the potentiometers only. The hum might be reduced by isolating the pots. I remember the volume pot being grounded to the board by a wire.

e_fortier · 28th April 2009, 04:52 PM

Hi,

If the input caps are 10uF this could be the case of the turn-off thump, depending on the input resistor these could probably be reduced to 2.2uF or 3uF.

The pot could be grounded to eliminate the hum while touuching the case or change the knob for a silver plastic one.

The led is an easy fix, I rather have the led ON when the unit is actually on.

Try to add a small cap across the speaker terminal (tantalum of very small value) this should reduce the hiss from your tweeter.

Looking forward to receive mine in about 2 wks.

Eric

Gmorris · 28th April 2009, 06:53 PM

Thanks for the tip Eric. I'll be interested seeing how you end up modding yours. I wasn't sure if the increased capacitance on the input was advantageous or not.

Some people earlier in the thread seemed to like the sound best after by-passing the op-amp and tone controls.

You can see the wire going from the volume pot case to the board in the attached photo.

27th April 2009, 07:13 AM	#204
col diyAudio Member Join Date: Feb 2008 Location: Melbourne, Victoria, Australia	just ordered one too. col. __________________ http://www.minirig.org.au

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25th April 2009, 12:03 AM	#201
e_fortier diyAudio Member Join Date: May 2001 Location: Twilight zone	Hi, At $25 USD + shipping I coudn't resist so I bought the newer version (TA2020-020 v3.1) last night from Export-Genie on e-bay. Did anyone came out with a list of mods yet ? Cheers, Eric

25th April 2009, 12:11 AM	#202
e_fortier diyAudio Member Join Date: May 2001 Location: Twilight zone	Me again By looking at the pics it looks like (I do not have mine yet) they have put a 14V Zener at the DC inlet, this is a neet idea. Anyhow, maybe someone can confirm this. Eric

26th April 2009, 01:07 AM	#203
JWFokker diyAudio Member Join Date: Feb 2005 Location: Kingston, NY	I just ordered one of these today. I guess T-Amps don't generate much buzz these days because this thread is the only discussion of the Lepai amps that I've come across, in English at least.

27th April 2009, 08:09 PM	#205
Gmorris diyAudio Member Join Date: Mar 2005 Location: MusicCity	The amp arrived today. I hope to plug it in later tonight. Now I just need some solar panels to trickle charge my SLA battery.

28th April 2009, 02:23 PM	#206
Gmorris diyAudio Member Join Date: Mar 2005 Location: MusicCity	The little amp seems to work as it should. I still haven't had time for much listening. I did remove the op-amp and replace it with a socketed LM4562. I could only hear low-level hiss from my tweeters if I had my ear within an inch or two from them. There was also audible low-level hum (not noticable from more than a foot away) if I touched the case. DC on the output was around 55 mV. There was some turn-off thump but not too bad. The power button does not affect the blue LED....it stays on as long as the power supply is connected. I also noticed that the two small electrolytics closest to the volume pot appear to be the input caps. Positive goes from input to the pot to the caps. These caps were labeled 2.2uF on the board but 10uF on the caps. Also, a 47uF cap between the opamp and the tripath chip (next to the heatsink) was labeled 100uF on the board. Overall, it seems to be a great deal. And I like the metal case better than the plastic SI / Dayton amp...

28th April 2009, 03:02 PM	#207
JWFokker diyAudio Member Join Date: Feb 2005 Location: Kingston, NY	Well, if I remember correctly the SI T-Amp had a "floating" ground, which is part of the reason why they used a plastic enclosure, but that used a TA2024 instead of a TA2020, so I don't know if it's directly comparable. But it would seem to me that it probably shouldn't be grounded to the case, even though it is. Also, can the DC at the output be remedied with a small cap across the terminals like on the SI T-Amp?

28th April 2009, 04:03 PM	#208
Gmorris diyAudio Member Join Date: Mar 2005 Location: MusicCity	55mV dc offset would be pushing it for a headphone amp but I don't think it's too bad for speakers. Dunno about the cap across the terminals... The board seems to be attached to the case through the potentiometers only. The hum might be reduced by isolating the pots. I remember the volume pot being grounded to the board by a wire.

28th April 2009, 04:52 PM	#209
e_fortier diyAudio Member Join Date: May 2001 Location: Twilight zone	Hi, If the input caps are 10uF this could be the case of the turn-off thump, depending on the input resistor these could probably be reduced to 2.2uF or 3uF. The pot could be grounded to eliminate the hum while touuching the case or change the knob for a silver plastic one. The led is an easy fix, I rather have the led ON when the unit is actually on. Try to add a small cap across the speaker terminal (tantalum of very small value) this should reduce the hiss from your tweeter. Looking forward to receive mine in about 2 wks. Eric