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...
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...
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?
Also, can the DC at the output be remedied with a small cap across the terminals like on the SI T-Amp?
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.
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.
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
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
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.
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.
Attachments
I'm assuming the opamp is acting as a pre-amp stage of sorts. People have reported better results when using a pre- with their tripath amps. If you already have a nice pre, I would guess bypassing the lepai input stage would result in the best sound.
I'm going more for high-quality portable sound so will probably leave the input section in place.
I'm going more for high-quality portable sound so will probably leave the input section in place.
Hi,
My MP3 player is powered by a single 1.5V AA battery so maybe the pre-amp is there to boost the voltage from the MP3 input and maybe the RCA inputs are fed directly into the TA2020 since the output of most CD/DVD player are above 1.5Vpk. This is pure theory since I do not have mine yet
Once I have it I will post my mods.
p.s. This is cheap fun
Regards,
Eric
My MP3 player is powered by a single 1.5V AA battery so maybe the pre-amp is there to boost the voltage from the MP3 input and maybe the RCA inputs are fed directly into the TA2020 since the output of most CD/DVD player are above 1.5Vpk. This is pure theory since I do not have mine yet
Once I have it I will post my mods.
p.s. This is cheap fun
Regards,
Eric
I only checked the amp functionality before replacing the opamp so I'm not sure how much of a difference it made. I figured it could only make it better and it was a fairly straight forward mod. I couldn't find my solder wick but that would have sped the process up. The socket makes it easy to swap in other dual opamps...I probably won't swap the original back in though.
The rca and mini inputs are both connected to the opamp. Also, I could barely hear sound using the mini input until I unplugged the rca cables.
I did some higher-volume listening last night and was impressed. I wouldn't mind dimming the blinding-blue LED down a bit though....
The rca and mini inputs are both connected to the opamp. Also, I could barely hear sound using the mini input until I unplugged the rca cables.
I did some higher-volume listening last night and was impressed. I wouldn't mind dimming the blinding-blue LED down a bit though....
Lepai TA2020
Just bought one of these from iwannebuy. http://myworld.ebay.co.uk/iwannebuy/ . Good price and quick delivery.
Tracing the circuit it appears that the 'POWER' switch on the front is not an on/off switch but just mutes the TA2020. That is why the LED stays on when the switch is off. Think I will rewire it to turn off the supply instead.
There is also a circuit that mutes the TA2020 if the input (supply) voltage is >14v. This is what the 14v Zener is for. The max voltage for this chip being 16v. This is going to make it difficult to use in a car as the battery charging voltage can reach over 14v. It confused me until I traced out the circuit
The op amp is used as a preamp after the volume control with a gain of about 5 - presumably to compensate somewhat for the loss in the tone controls - about 20dB or some 10x.
I was quite impressed with the reproduction however ( Pink Floyd - Division Bell) but only into my bench speakers. I'll try it out on some proper ones after I have measured the offset.
Tony
Just bought one of these from iwannebuy. http://myworld.ebay.co.uk/iwannebuy/ . Good price and quick delivery.
Tracing the circuit it appears that the 'POWER' switch on the front is not an on/off switch but just mutes the TA2020. That is why the LED stays on when the switch is off.
Think I will rewire it to turn off the supply instead. There is also a circuit that mutes the TA2020 if the input (supply) voltage is >14v. This is what the 14v Zener is for. The max voltage for this chip being 16v. This is going to make it difficult to use in a car as the battery charging voltage can reach over 14v. It confused me until I traced out the circuit
The op amp is used as a preamp after the volume control with a gain of about 5 - presumably to compensate somewhat for the loss in the tone controls - about 20dB or some 10x.
I was quite impressed with the reproduction however ( Pink Floyd - Division Bell) but only into my bench speakers. I'll try it out on some proper ones after I have measured the offset.
Tony
I ordered this amp from export-genie, it arrived some time ago.
First thing: device was DOA ;/ - there was no sound at all.. It turned out that on/off switch area was completely messed up on the PCB (tracks were cut, drops of solder lead etc.). The only think this switch does is to ground pin 11(mute) on TA2020. This pin must be grounded in order to get any sound from the amp - so I was able to fix this switch pretty easily. I contacted the seller and was assured this won't happen again, however it clearly looks like quality control process of these amps is lacking at best
Second (much more important) thing: I hooked this amp to a pretty generic laptop psu (12V, 4A) and to my modest speakers set (Mission 560i). And.. WOW! This sounded really good! It was so clean and transparent. Not thinking much, I instantly replaced this inferior op-amp with LM4562, powered it up and.. was completely stunned..
I never thought it can make such a difference! Now sound is smooth as silk, so detailed and very addictive. I can''t stop listening to this little miracle-device! And soundstage... soundstage! Now I realize that before listening to this amp I didn't have idea what 'soundstage' exactly means. I was pretty sure that this is some wicked placebo effect, so I did A/B comparison with my old Yamaha 'natural sound' amp. Yamaha was completely devastated in this duel. It sounded so flat, dull, uninviting. I didn't understand how could I enjoy this amp so much before. Was tempted to throw it out of the window right away.
This cheesy, 30-buck chinese device changed completely my view onto the music. I stopped believing in high-quality cabling, audio-grade capacitors and other expensive audio-voodoo stuff.
I started to believe in real technology like this in TA2020.
I consider these 30$ to be probably the best spent money in my whole life (and definitely the best in terms of audio equipment). I never thought my old-fashioned speakers have such a potential. Smile appears on my face every time I look at this crappy-looking Lepai device
Worth to mention: I am using quite a decent source - HT Omega Claro Halo soundcard. When I connected my mp3 player, outcome was still very good, but all these subtle details and 'absolute-sound effect' disappeared somewhere.
My tips for the owners:
1. Get rid of build-in op-amp right away. Swap it out with something decent like LM4562. This will unleash full potential of TA2020. I guarantee you will be amazed with the result.
2. Tone controls are a bit tricky. Even a little manipulation changes sound signature completely. It takes some time to find an ideal position. I am thinking about bypassing them completely in order to improve sound even further (can't imagine how this device can sounds better).
3. This is obvious, but use good-quality source for the best effect.
4. Expect there might be some manufacture issues with your unit
I hope my mini-review will help someone. I am getting back to rediscovering my whole library
First thing: device was DOA ;/ - there was no sound at all.. It turned out that on/off switch area was completely messed up on the PCB (tracks were cut, drops of solder lead etc.). The only think this switch does is to ground pin 11(mute) on TA2020. This pin must be grounded in order to get any sound from the amp - so I was able to fix this switch pretty easily. I contacted the seller and was assured this won't happen again, however it clearly looks like quality control process of these amps is lacking at best
Second (much more important) thing: I hooked this amp to a pretty generic laptop psu (12V, 4A) and to my modest speakers set (Mission 560i). And.. WOW! This sounded really good! It was so clean and transparent. Not thinking much, I instantly replaced this inferior op-amp with LM4562, powered it up and.. was completely stunned..
I never thought it can make such a difference! Now sound is smooth as silk, so detailed and very addictive. I can''t stop listening to this little miracle-device! And soundstage... soundstage! Now I realize that before listening to this amp I didn't have idea what 'soundstage' exactly means. I was pretty sure that this is some wicked placebo effect, so I did A/B comparison with my old Yamaha 'natural sound' amp. Yamaha was completely devastated in this duel. It sounded so flat, dull, uninviting. I didn't understand how could I enjoy this amp so much before. Was tempted to throw it out of the window right away.
This cheesy, 30-buck chinese device changed completely my view onto the music. I stopped believing in high-quality cabling, audio-grade capacitors and other expensive audio-voodoo stuff.
I started to believe in real technology like this in TA2020.
I consider these 30$ to be probably the best spent money in my whole life (and definitely the best in terms of audio equipment). I never thought my old-fashioned speakers have such a potential. Smile appears on my face every time I look at this crappy-looking Lepai device
Worth to mention: I am using quite a decent source - HT Omega Claro Halo soundcard. When I connected my mp3 player, outcome was still very good, but all these subtle details and 'absolute-sound effect' disappeared somewhere.
My tips for the owners:
1. Get rid of build-in op-amp right away. Swap it out with something decent like LM4562. This will unleash full potential of TA2020. I guarantee you will be amazed with the result.
2. Tone controls are a bit tricky. Even a little manipulation changes sound signature completely. It takes some time to find an ideal position. I am thinking about bypassing them completely in order to improve sound even further (can't imagine how this device can sounds better).
3. This is obvious, but use good-quality source for the best effect.
4. Expect there might be some manufacture issues with your unit
I hope my mini-review will help someone. I am getting back to rediscovering my whole library
"1. Get rid of build-in op-amp right away. Swap it out with something decent like LM4562. This will unleash full potential of TA2020. I guarantee you will be amazed with the result."
Is this something a complete novice can do (and if so - how?), or does it require soldering and such?
I bought one of these Lepai amps a while ago. I'm hoping it arrives today. I bought a power supply for it too, which just arrived yesterday (13.5V, 2.66A)
Is this something a complete novice can do (and if so - how?), or does it require soldering and such?
I bought one of these Lepai amps a while ago. I'm hoping it arrives today. I bought a power supply for it too, which just arrived yesterday (13.5V, 2.66A)
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