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Old 27th March 2011, 09:28 AM   #751
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Location: Seoul
For those interested, this is a picture of the newest board (dual opamp and tone bypass).

Click the image to open in full size.

There is no component underneath.
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Old 27th March 2011, 05:27 PM   #752
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Hi to all! Where can I by the best version of Lepai on eBay today? Thanks.
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Old 27th March 2011, 06:17 PM   #753
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Is LP-2020A+ much better than LP-2020? I think difference is not so noticeable (and LP-2020 have no SMD and it can be easier to mod, right?).
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Old 28th March 2011, 05:18 AM   #754
drips is offline drips  United States
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Just got my two LP-2020-A+ from Parts Express. First I want to thank everyone who contributed to this thread! Because of you knowledgeable folks I decided that the Lepai was going to be acceptable out of the box and could potentially be much better with a little tweaking.

Inside they look like the image candoumi posted on this page which means some of the mods posted about earlier models aren't applicable. I'm wondering if anyone has a comprehensive list of things to do the the newest model, possibly in order of greatest improvement on down. ernperkins mentioned swapping the op-amps from 4558s to LM4562s but alas, I don't have any friends with SMD capabilities. I am also wondering if anyone has done a good test of the A+ model to determine what actually needs to be replaced after all of Lepai's changes to it.

[* I just had a closer look at candoumi's photo and it looks like the op-amps are marked JRC 456something.]

I tested the amps side-by-side with my set-up which is Apple Airport Express --> Lepai --> Bose 161 speakers. I'm using one rig in a small bedroom and one in the bathroom and with Air Play we can play music wirelessly from an iPhone or any computer running iTunes. [I'm no Apple fanboy but I can't recommend the Airport Express enough. Having easy wireless audio totally changed the way I listen. I listen much more now and to a wider range of stuff.] When I switched from one amp to the next I was shocked at the HUGE difference in loudness from the amps. The loud one with volume knob set at 9 o'clock is as loud as the other set at 12 o'clock. Everything else seems ok though, but I'm going to return one once I can figure out which is out of whack. The loud one seems punchier too, but almost too loud for it's own good...

As it stands I'm pretty happy with the units. They're nice and small, and sound good enough for $20. I'm still interested in improving them though because I can tell that ear fatigue could be an issue. They're not primary listening rigs though so it may not be important. I am also thinking about some kind of audio-sensing switch in the bathroom unit because it'll be buried in a closet.

I'm somewhat capable when it comes to electronics stuff but far from comfortable so if I had gotten the old model the contributions from the posters would have made my day. Thanks again for your help and sharing your knowledge!

Last edited by drips; 28th March 2011 at 05:32 AM. Reason: I took a closer look at candoumi's photo
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Old 28th March 2011, 05:52 AM   #755
drips is offline drips  United States
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Just opened mine again and saw the 4558 marking on the op-amp. I guess I just squinted a little too much at the photo...
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Old 29th March 2011, 08:26 AM   #756
Excile is offline Excile  Denmark
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What is opamp and tone bypass?
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Old 29th March 2011, 09:47 AM   #757
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"op-amp" is the short for "operational amplifier"
The "tone bypass" is a switch which allows to bypass the tone stage of the amp.
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Old 30th March 2011, 05:14 PM   #758
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Smile LP-2020B

I got another one off ebay arrived a few days ago. Its an LP-2020A+ on the case, but the board inside is LP-2020B... It has the 'protection relay', surface mount components but only one op-amp. I mapped out the relay protect circuit, but I'm not convinced by it... Its still connected to the fault pin and looks like it will toggle the relay off if this goes high, but it is also connected to the mute/over voltage circuit. This will perform an automatic reset of the fault condition (see datasheet), which I don't think is desireable. Another thing - the relay only switches one side of each differential output - so for example, a short could occur on either pin and will not necessarily be disconnected by the relay. I'm not sure why this relay protect is necessary other than to prevent the switch on pop - but then why connect to the fault pin? From the tripath data sheet:
"The TA2020-020 is guarded against over-temperature and over-current conditions. When the device goes into an over-temperature or over-current state, the FAULT pin goes to a logic HIGH state indicating a fault condition. When this occurs, the amplifier is muted, all outputs are TRI-STATED, and will float to 1/2 of VDD."
What do other people think of this 'relay protect'? If I get time I'll draw up the schematic I have and post.

I've made the following mods to the new one:
1. Removed overvoltage circuit and relay circuit - tied mute to gound and added an LED to the fault pin.
2. Removed tone control/volume control and op-amp
4. Replace input caps with 2.2 uF (they were 1.75uF)

I'm very pleased with the result - it does sound much better without the tone controls as an earlier post suggested - better bass response, and I think the treble sounds sharper too. Using a 12V regulated power supply I don't need the protection circuit, or the extra diode on the output (data sheet says they are only needed for voltages >13.5V). The switch on 'thump' is minimal once the op-amp/tone control is removed, as an earlier post suggested.
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Old 31st March 2011, 12:56 PM   #759
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Default Lepai 2020B relay protect circuit

OK, here is the relay protect circuit as best as I can trace it. It is all surface mount. The thing that concerns me is the connection between the fault/relay circuit and the overvoltage/mute circuit. In the case of Fault going high, I think this would 'toggle' the mute pin which resets the fault. But if the fault condition persists, will this lead to damage to the TA2020?
Attached Images
File Type: gif Lepai_relay_2020B.gif (55.9 KB, 744 views)
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Old 1st April 2011, 12:33 PM   #760
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Hi guys. I hope you can help me. I'm afraid I'm not technically minded.

I've just purchased a Lepai Tripath TA2020 and have connected a pair of old Sony speakers to it.

The thing is when I switch the little amp on a loud pop comes from the speakers and they physically pop out. Can I ask the following questions:

a) Is this doing any harm to my speakers ?
b) Is it because the speakers aren't rated high enough to receive the amp's output or do you think there is a fault with the amp ?
c) Will getting a higher rated pair of speakers cure this ?
d) Can I stop it without getting a new pair of speakers

Thanks for any help you might be able to offer.
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