LP-2020A+ mod thread

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Amplifier:Lepai T Amp - diyAudio

Then we need at least a 12v Power Supply Unit and preferably not above 13.5v (because above of that the Lepai zenner diode for protection will reduce it, and will be useless, and some users reported that sound quality decreases). The higher the Voltage supplied, the more power will be able to output the amp, so 13.5V are desirable.
Must be too outdated then.
 
Well i read that off the lepai-2020 wiki page on the DIYaudio website, that's why i was confused by it.


Today I finally got this power supply: (2.5 weeks shipping)
12V 3.2A Power Supply Transformer for LED Light Bulb (AC 110~240V) - Free Shipping - DealExtreme

Adjustable range between 9.3V - 14.2V. And it does pretty well in holding that voltage.
Set to 14.2V, even at 2.5amps load there is 14.2V at the terminals, my amp gets ~13.8 and the rest is lost on wires. Probably going to double them up or something, as they are relatively short already.

The output inductors are getting warm after a short stress test (just below clipping, 13.8V @ 2.5A - 5Minutes), the added schottkys seem to do their job, as they also heat up somewhat.


For now I think I am finished with modding it.
So far it sounds great and can go really loud without dipping out.
That PSU also is definitely worth the 10$, if you want to drive the TA2020 close to its limits without clipping.
 
Hi guys, first time posting here!

I bought the amp last week, and already started modding. There was just problems and problems for me... luckily I managed to find out what happen just today.

Just a note for you guys when taking apart the amp from the case dont put too much pressure on the screw for the RCA inputs! The extremely thin little wire that connects the RCA to ground might just break off, that was what happen to me and I spent days finding the problem and reflowing every little SMD! haha silly me.

For extra support, spam solder on the ground pin for the RCA, it is the one in between the connectors and the board to strengthen it. You can see it from the back.

Thing done... my inspiration came from redshift, so most of it is similar to his.

1) Change all the caps to low ESR Panasonic caps, these are really good and value for money!

- Powercap from 3300uF to 5600uF+0.22uF and soon to 2x(5600uF+0.22uF) :D
- 2.2uF input caps to polyester Wimas MKS, was deciding between EVOX or Wima! any1 knows the difference? The MKPs are just too huge, smaller the better for me :)
- 1uF caps to polyester, hard to find low ESR for these so polyester the way to go
- Removed diode D2, I really thought it was a stupid diode.

Already sound pretty good here!

- Both op amp to OPA2132... ugh the decision between AD823, took the burr brown one due to low current req in the end anyone recommend otherwise?
- Add solder and reflow every joint for through pin and SMD components, the joints are of really bad QC

Still to come

- Change all the inductors to cheap(okay value for $$) toriods (I have a budget!), and the power inductor to a shielded, higher ampre >4.2A low inductance ~3.3uH for safety
- Addition of 4 schottky, got some SMD schottky lying at home rated 30V
- Addition of 47uF bypass to V+/V- of both op amp. If I am not wrong, this is where the question comes

Anyone got any idea whether there is already a cap to bypass the op amp? And I am supposed to bypass the V+/V- pins and not the others right?

Decisions and decisions, I wished there was a button to change op amp on the go so I have both AD and OPA on the board! Any other op amps recommended?

No op amp bypass for me! Find the op amps gives the sound more volume and airy feeling and smoother bass

Thanks for reading and happy modding! Pictures after I get my toriods and finish modding the rest!
 
Nice to hear you made some improvements lwj5!

I really like the OPA2132 in everything I've tried it in. I compared once to a LME49710HA, but the circuit was borderline oscillating and it had a lot of sibilance. Being that the 49710 is a much higher speed opamp, that's no surprise.

C26 and C27 are local (0.1uF?) ceramic bypass caps for each opamp, and C28 is the large local bulk capacitor for them both. As the opamps are being run single supply, bypassing V+ to V- is the same as V+ to ground.
 
Hi guys, first time posting here!

I bought the amp last week, and already started modding. There was just problems and problems for me... luckily I managed to find out what happen just today.


1) Change all the caps to low ESR Panasonic caps, these are really good and value for money!

- Powercap from 3300uF to 5600uF+0.22uF and soon to 2x(5600uF+0.22uF) :D
- 2.2uF input caps to polyester Wimas MKS, was deciding between EVOX or Wima! any1 knows the difference? The MKPs are just too huge, smaller the better for me :)
- 1uF caps to polyester, hard to find low ESR for these so polyester the way to go
- Removed diode D2, I really thought it was a stupid diode.

Already sound pretty good here!

- Both op amp to OPA2132... ugh the decision between AD823, took the burr brown one due to low current req in the end anyone recommend otherwise?
- Add solder and reflow every joint for through pin and SMD components, the joints are of really bad QC

t!

Couple of points; 'genuine' 2.2 uf Wimas are Huge things .. seriously unlikely you could fit them to the board or in the case.
The Lepai tone controls are sad efforts. Compared to a decent manufacturer's tone setup, the Lepai lashup is simply poor.
Total waste of time.. sound quality improvement wise IMO.
But then Fiddling can be fun :)
OEM inductors can be rewound DIY for almost no cost and minutes of your time..these are 16 turns oem.. Just use a thicker magnet wire with same number of turns.
 
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hi all, its cool to see others playing around with this amp.

I chose it for a project simply because it was the smallest, cheapest one I could find. Now I am trying to re-use it for a small stereo. I am trying to drive two B3N full range woofers and needed to slim it down to better fit in the enclosure. I would like to ditch the tone control garbage but am not sure where to start. I have had some basic EE courses but am still a relative newb.

I also dont care to have the volume control, I figured I would set the volume at about 80% and then just control the volume of the source. I have removed the potentiometers, but nothing else. In a "less intelligent move" I tried to replace the volume POT with a resistor or two. In a careless mistake, I shorted a few of those contacts. I cannot test my circuit until I solder the volume POT back on, but is is possible that I did any damage by shorting some of the leads to the POT?

Since I have not found a more compact alternative to this amp, I am looking into replacing the components as others have mentioned. Can anyone recommend a supplier for these parts?

Thanks!
 
Large Wimas are pricey for result delivered imo.
Smaller ones are mediocre things, at best. Replace one of those with even the cheapest Film 'n foil and be amazed.
Take the oem Teeny inductors Off the board , unwind the hair thin windings, then rewind with the same number of turns (16) of heavier gauge Magnet wire. Instant upgraded Inductor coils, for a half hour's work and 1$ of wire.
Plus they Fit ..easily.. back on the pcb.

Go to: Amplifier:Lepai T Amp - diyAudio
and scroll down to the photo of the bypassed tone controls then do that exact mod.
Although the Large Blue Alps pot made absolutely No sound difference when I tried it. Utter waste of time is my opinion, after actually trying it.
Although IF seriously worried about Pots one would be fitting a Goldpoint stepped attenuator...( as if :rolleyes: on a 15$ amp gizmo.. rather than a Fake Blue Alps.
But Hey.. If you must.
 
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