Lepai T-Amp with TA2020

[panda360]

Originally posted by Calamaro
panda, just bypass the electrolitic with the 100nF film cap: solder its legs on electrolitic legs. The film cap (100nF) is non polarized so you don't have to pay attention to + and - legs.
If you prefer you can solder the little film cap under the board

Hi Cal,

I just finished the modification by passing the opamp. Except input cap. (I can't good quality 470uf cap at this moment. ) The sound quality is better than before. But the sound level is lower. Before mod, I turn to 12 oclock position is enough. After mod, I need to turn to 1 o'clock position.

Anyway, I am happy with this amp.

Thank you.

[MikeHunt79]

Originally posted by col
just removed the zener and put a 2k resistor with led on the No18 pin. drilled a hole in the front between the tone controls to mount. So I now have a fault led

col.

Nice work.

Some people at the 41Hz forum suggest shorting the speaker outs is a good way to test if the fault LED works, but I'm not sure if I'm that brave to do it to my Lepai!

I'm making a perpex faceplate for mine, I've found that the pot I want to use is a little large so I've had to improvise...

[col]

The led comes on then gradually goes out if I pull the power cable out (under voltage fault). Thats about as much testing I'm going to do. It's the same behavior as other Tripath amps I have.

col.

[MikeHunt79]

Originally posted by col
The led comes on then gradually goes out if I pull the power cable out (under voltage fault). Thats about as much testing I'm going to do. It's the same behavior as other Tripath amps I have.

col.

I didn't know that, I think as I'm making a new faceplate I'll leave a hole for a fault LED, it's a good and simple addition IMO.

[Calamaro]

Originally posted by panda360
the sound level is lower.

Did you replace input resistors?

[panda360]

Originally posted by Calamaro


Did you replace input resistors?

Hi Calamaro,

Yes-replace input resistors with 20/22k

[MikeHunt79]

Hey guys, another Lepai arrived today, and it appears to be a little different, I guess this could be Mark 3?

Here's a pic, new (mk3) on the right and my old (modded mk2) on the left:


As you can see the mk3 has notches for mounting bolts, and I've also found that the switch now turns the LED on and off, but there is a big turn on thump... I guess the switch must switch the power and mute is now disabled?

I haven't opened it up yet, but when I do I'll post some more pics.

[Calamaro]

I have that one (the new). I think it has the same pcb.

[MikeHunt79]

I think I've finished tinkering with mine for today:


The red LED on the bottom left is the fault LED, the orange wire has a 2k2R resistor from pin18 for the fault LED. The big cap on the left is exactly like Calamaro's power mod. I've also wired 4 x white LED in series so when I'm powering this amp from my Li-ion battery pack I can see when the voltage goes below 9v when the LED's go dim.

I've replaced the volume pot with a 50k A&B pot which is a little large so I've had to have it floating and have the front panel hold it in place.

I've made a new front panel from 4mm perpex, and because the front panel is now removable, I can now mount decent quality RCA connectors on the rear panel. I've gone for a 4pin molex connector for the speaker connectors so I can quickly disconnect and reconnect this in the car...

View from front:


I need to buy a knob for the volume pot, right now I'm just using 6mm washers taped together! I'm used a drilled 2p coin as a washer for the volume pot.

Once the new op-amps arrive I think I'll try swapping out the JRC4558, and I have still yet to try tone control bypass and I still need to wire in a mute switch.... Right now it's just shorted so it's unmuted the whole time.

Originally posted by Calamaro
I have that one (the new). I think it has the same pcb.

Yep, I just taken it apart and it is the same PCB... Pic:


I guess this could be a the early version after all? Did that one have the LED switch on and off with the switch on the front?

[Calamaro]

I guess this could be a the early version after all? Did that one have the LED switch on and off with the switch on the front?

Please check both boards under the switch: just a different wiring.
Congratulations for your hard work!