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Class D Switching Power Amplifiers and Power D/A conversion

LP-2020A+ mod thread
LP-2020A+ mod thread
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Old 5th November 2013, 05:20 PM   #291
Redshift187 is offline Redshift187  Canada
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Join Date: Aug 2008
Originally Posted by Kaeon View Post
Hey guys new here, I just ordered the upgraded output caps, and 5600uF low esr input cap from mouser as reconmended by "XtremeRevolution" at Parts Express forums. While I was following the post he mentions that there are 3 holes that you can solder the output caps to and that we should use the outer holes as the new replacement caps are of a larger size. I looked over my board and notice that I have two relays instead of one so I don't have a 3rd hole on the two bottom output caps. Has anyone done this upgrade with a board like this? Is it OK to squeeze the legs of the capacitor together to fit in there?
It's perfectly fine to squeeze the leads together. Just try to get the cap leads as far into the board as possible, to reduce the "wire" length".
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Old 7th November 2013, 02:13 AM   #292
Bare is offline Bare  Canada
diyAudio Member
Join Date: Dec 2001
Location: vancouver
Originally Posted by iandroo888 View Post
is there any guides to doing any of the suggested mods? that has like a parts list also?
Guess what DIYAudio has a Lepai WIKI
Amplifier:Lepai T Amp - diyAudio
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Old 26th March 2014, 09:29 PM   #293
jasbear is offline jasbear
diyAudio Member
Join Date: Mar 2014
Hi i'm new here and about start modding my amp.

I only need one answer more. Is there a way to prevent the amp from clipping but still keep the bass and treble controls?
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Old 28th March 2014, 07:02 AM   #294
dimitarnc is offline dimitarnc
diyAudio Member
Join Date: Mar 2014
Yes, this will be interesting to know how to make. I too want to keep the controls and swapping the OPAMPs with better ones. A couple of questions more:
1. I see some of you guys decided to change the small caps C34, C37 (near the Inductors). I see in the datasheet of TA2020 the value is 0.1uF (100nF), but in several posts I see 0.01uF ? Is this a mistake or there is some reason? I can buy WIMA polyester of both values, so please advise.
2. Another question regarding the Zobel Network - what is the reason to change the 10 ohm resistors with 6.8 ohm and the related change in C35, C39 with 0.22uF? I have 4 ohm speakers and don't know if that change is applicable for me, or to stay with default values (10 ohm, 0.47uF). I have 0.6W resistors of both types.
3. Some posts are dealing with the Zener diode D2. Is safe to remove it when adding the additional Schottkys? I should replace with direct wire bridge in this case?

I have Microlab SOLO 7 speakers converted to passive (the embedded Amp died). They are 4 ohm and probably suitable for the Amp. If there are other recommendations please, advise. I will swap the other caps too with Low ESR ones, the power supply is 12V 6A.
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Old 15th April 2014, 06:15 PM   #295
dimitarnc is offline dimitarnc
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Join Date: Mar 2014
So I want to share with you guys how I swapped the parts of this little AMP. It finally arrived and is built with very cheap parts, actually it's a crap low quality peace. I directly swapped almost everything and it now sounds beautiful
Here is the part list:
Audio input smd caps C30 C31 near the input RCAs and the audio input caps to Tripath chip C20 C21 - replaced with Wima 2.2uF 63V 10% MKS2
All electrolytic caps replaced with Low ESR ones - I have here only Taiwanese HITANO Low ESRs so no other choice for me. The main power filter C1 was replaced with 4700uF one and additional ceramic cap 220nF 50V X7R P5 added at the bottom side of the PCB. The values of the other electrolytics are kept like the original.
The power input choke L1 was swapped with Panasonic 3.3UH, 0.016OHM, 5.2A.
The audio output chokes L2 L3 L4 L5 - swapped with Panasonics ELC10D100E 10UH, 3.9A, 0R026
Audio output caps C32 C33 C36 C38 swapped with Wima 470nF 63V 10% MKS2
These two changes are according the datasheet of Tripath:
Audio output caps C35 C39 swapped with Wima 220nF 63V 10% MKS2
Audio output resistors R38 R39 - swapped with 10 Ohm 1/2W
It seems the board was purely designed with equal caps in the output section but I decided to follow the datasheet for 4 Ohm speakers
I replaced too the two smd caps C34 C37 with Wima 10nF 63V 10% MKS02 which I placed underneath the PCB (it was easier for me)
C9 replaced with Panasonic ECW-F2W104JAQ .1F 450V
Finally I decided to try the AMP with the default OP AMPs after all these changes - it sounds beautiful with my Microlabs SOLO7s converted to passive I was surprised how nice and powerful it was and with clean sound. The audio feed is from Asus Xonar DX, the power source is 12V 6.5A power supply brick for LEDs. For now the AMP is good enough for me and I left the OP AMPs unchanged. However the mentioned problem with power On/Off popping sound is present. If someone has a solution to that, please share it with us.
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Old 19th July 2014, 10:28 PM   #296
rwzahora is offline rwzahora  United States
diyAudio Member
Join Date: Apr 2008
Default another set of LP-2020A+ mods

I needed a small amplifier and ended up purchasing a Lepai LP-2020A+ 20W unit for US$21. At first listening I was not impressed so decided to incorporate some of the suggestions from this forum as well as those on the Parts Express web page.

The board in my unit was marked Lepy LP-2020A+ 131005PCB. This is a more recent version than some of the boards in earlier discussions. I concentrated on the input op amps and the signal-coupling capacitors. In addition I replaced the output inductors. I'm not sure how much of a change the inductors made but at least I now know the specs on the parts. Finally, I updated some of the supply decoupling capacitors. I also added some 0.1 uF chip caps on the bottom of the board between the leads of all the decoupling electrolytic caps. At audio frequencies I don't think this makes much of a difference but I had the parts in the junk box so decided to use them.

A photo of the modified board is attached. The sound from the amp is significantly better and meets my needs. I'm quite happy with the $17 investment in the upgrade parts.

The parts list with Digi-Key part numbers follows -

(2) 497-10230-1-ND
STMicroelectronics TL082BIYDT IC OPAMP JFET 4MHZ 8SO
U1, U2

(4) 732-3747-ND
Wurth Electronics Inc 744732100 INDUCTOR 10UH 4A 8075 RAD
replaces old inductors which are 0.026 ohm, new are 0.023 ohm
L2, L3, L4, L5

(1) 565-1065-ND
United Chemi-Con CAP ALUM 3300UF 25V 20% RADIAL
replaces 2200uF 16V 85C

(10) P4675-ND
replaces 1uF 50V 105C
C4, C10
two stacked bottom-to-bottom replaces 3.3uF 50V 105C NP
C20, C21
two stacked side-to-side replaces chip caps ~2uF
C30, C31
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Old 20th July 2014, 01:08 AM   #297
rwzahora is offline rwzahora  United States
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Join Date: Apr 2008
Default photo for last reply

Sorry, my photo didn't make it into the last reply. Here it is.
Attached Images
File Type: jpg Lepai-LP2020A+-mod.jpg (616.7 KB, 417 views)
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Old 30th December 2014, 03:17 PM   #298
Chov1ch is offline Chov1ch  Croatia
diyAudio Member
Join Date: Jun 2013
Hello i have one problem.. so i think i broke volume potentiometer on my lepai so i would like to bypass it (remove) so you can only change volume on source device.. how its possible?

Do i need to connect it with wire like this: Screenshot by Lightshot ??

Please fast reply thanks
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Old 31st December 2014, 05:31 PM   #299
sofaspud is offline sofaspud  United States
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Location: San Antonio
Any wire will do; it doesn't need to be anything special. Just use it to jumper from the input side of the potentiometer circuit to the wiper side of the potentiometer circuit. And cut the old PC trace that runs to the pot input. I wouldn't fuss with removing the volume pot.
It is error only, and not truth, that shrinks from enquiry. - Thomas Paine
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Old 1st January 2015, 11:39 PM   #300
npnr is offline npnr
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Join Date: Jan 2015
Hi, I sometimes run my lepai from a 12v lead acid battery. Unfortunately when it's fully charged the voltage is sometimes too high and the amp won't work. I'm thinking that I need a low dropout voltage regulator, but I'm not an electronics engineer...


Am I on the right tracks? Has anyone solved this problem? Thanks in advance!
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