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  1. #41
    Join Date
    Feb 2007
    Location
    El Macero, CA
    Posts
    129

    Default Re: Modding the Lepai T2020A+

    Quote Originally Posted by neildavis View Post

    I would set the following priorities in modding this amp:

    3) The op amp. 4558's are not low distortion or low noise. There are many good options, but even the low cost TL082 would be a major upgrade.
    thanks ordered the op amps... thanks for a nice suggestions.

  2. #42

    Default Re: Modding the Lepai T2020A+

    I've seen a few discussions about bypassing the tone controls. But my 2020+ (new version) sounds a bit "tin can-ny" with the bypass button set to Direct. Too flat? I don't know - all I know is it sounds better with the treble boosted.

    Problem is, with the tone controls enabled, I can't crank the volume much past halfway without distortion. (In Direct mode, I can generally get up to about 2/3). This is into a 6 ohm satellite/sub set, and it seems to be pulling less than an amp at this volume - so maybe not a power supply issue?

    Which of the discussed mods, if any, will allow me to operate the thing with the tone controls enabled?

    (Unfortunately, I have neither the time nor the skillz to mess with any of the SMD components right now. Leaving for a desert trip in two days, and will be running the amp off at 12V battery.)

  3. #43

    Default Re: Modding the Lepai T2020A+

    2 Questions:

    1. Are the two surface mounted capacitors closest to the inputs the coupling capacitors and if so what are their values. marked C30/C31.

    2. I'm interested in coupling the two channels into one after the input. On the older ones, I used (2) 10k resistors and then joined them together and fed them into the 2 decoupling caps (2.2uf I think). This amp looks a lot different. Do you have any suggestions on how to do this? (that's really the only reason for the first question. Also, I used to replace these caps with better, poly caps.)

    Thank you very much,
    Nicholas

  4. #44

    Default Re: Modding the Lepai T2020A+

    Quote Originally Posted by nige838 View Post
    2 Questions:

    1. Are the two surface mounted capacitors closest to the inputs the coupling capacitors and if so what are their values. marked C30/C31.

    2. I'm interested in coupling the two channels into one after the input. On the older ones, I used (2) 10k resistors and then joined them together and fed them into the 2 decoupling caps (2.2uf I think). This amp looks a lot different. Do you have any suggestions on how to do this? (that's really the only reason for the first question. Also, I used to replace these caps with better, poly caps.)

    Thank you very much,
    Nicholas
    Someone more knowledgeable will have to answer that question for you, as I'm not as technically inclined as others to be able to answer that question for you.

  5. #45
    Join Date
    Feb 2007
    Location
    El Macero, CA
    Posts
    129

    Default Re: Modding the Lepai T2020A+

    Quote Originally Posted by neildavis View Post


    3) The op amp. 4558's are not low distortion or low noise. There are many good options, but even the low cost TL082 would be a major upgrade.
    I tried to replace my op amp, and messed up. I tried to cut the legs off first and PCB board came up... I have soldered amp6basic (41Hz) without difficulty, so unless u r very good with a solder gun, should reconsider...

  6. #46
    Join Date
    Dec 2010
    Location
    WV
    Posts
    3,934

    Default Re: Modding the Lepai T2020A+

    I tried to replace my op amp, and messed up. I tried to cut the legs off first and PCB board came up... I have soldered amp6basic (41Hz) without difficulty, so unless u r very good with a solder gun, should reconsider...
    Use low wattage or temp controlled solder pencil and solder braid and solder suckers and it can be done.

  7. #47
    Join Date
    Feb 2007
    Location
    El Macero, CA
    Posts
    129

    Default Re: Modding the Lepai T2020A+

    Quote Originally Posted by Sydney View Post
    Use low wattage or temp controlled solder pencil and solder braid and solder suckers and it can be done.
    is there a youtube video?, can u upload this?

  8. #48
    Join Date
    Dec 2010
    Location
    WV
    Posts
    3,934

    Default Re: Modding the Lepai T2020A+

    is there a youtube video?
    Bunches
    http://www.google.com/search?q=solde...vgc&hl=en&aq=f

    http://www.google.com/search?q=desol...i=g10&aql=&oq=

    I larned' the hard way - experience
    ( practice cannibalizing old circuit boards )

  9. #49
    Join Date
    Feb 2007
    Location
    El Macero, CA
    Posts
    129

    Default Re: Modding the Lepai T2020A+

    Quote Originally Posted by Sydney View Post
    Bunches
    http://www.google.com/search?q=solde...vgc&hl=en&aq=f

    http://www.google.com/search?q=desol...i=g10&aql=&oq=

    I larned' the hard way - experience
    ( practice cannibalizing old circuit boards )
    thanks for op amps, this is particularly good: http://www.youtube.com/watch?v=8UN3D2-f64A

    I may try again since I actually have one more Lepai...

  10. #50
    Join Date
    Aug 2011
    Location
    Annville, PA
    Posts
    22

    Default Re: Modding the Lepai T2020A+

    Quote Originally Posted by nige838 View Post
    1. Are the two surface mounted capacitors closest to the inputs the coupling capacitors and if so what are their values. marked C30/C31.

    Thank you very much,
    Nicholas
    The schematic shows these are 3.3uF capacitors. In my 2020A+ they are SMDs. I don't think they would be very easy to replace with polypropylene caps unless you got creative.

  11. #51
    Join Date
    Sep 2005
    Location
    Reston, VA
    Posts
    2,184

    Default Re: Modding the Lepai T2020A+

    Quote Originally Posted by xoaphexox View Post
    The schematic shows these are 3.3uF capacitors.
    If C30 and C31 are 3.3uF, they are most likely either X5R or Y5V (X7R is usually bigger than what is shown in the picture, although if the voltage rating is low enough it *could* be an X7R). Y5V caps are not good for audio. You can see some measurements of various ceramic dielectrics in the article on the Maxim-IC site: http://www.maxim-ic.com/app-notes/index.mvp/id/4333. The distortion introduced by a Y5V cap could be audible. It would probably be worth replacing these caps with at least X7R's--film would be even better.

    Click image for larger version. 

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  12. #52
    Join Date
    Aug 2011
    Location
    Annville, PA
    Posts
    22

    Default Re: Modding the Lepai T2020A+

    Quote Originally Posted by neildavis View Post
    If C30 and C31 are 3.3uF, they are most likely either X5R or Y5V (X7R is usually bigger than what is shown in the picture, although if the voltage rating is low enough it *could* be an X7R). Y5V caps are not good for audio. You can see some measurements of various ceramic dielectrics in the article on the Maxim-IC site: http://www.maxim-ic.com/app-notes/index.mvp/id/4333. The distortion introduced by a Y5V cap could be audible. It would probably be worth replacing these caps with at least X7R's--film would be even better.

    Click image for larger version. 

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    Thanks for the suggestion - I assume you are talking about replacing with SMD devices - if anyone decides to go this route let us know how it works out! Very curious about replacing the input coupling caps, inductors, and op amps.

  13. #53

    Default Re: Modding the Lepai T2020A+

    Im a novice when it comes to electronics but love taking the time to fix things and ive been following lepai 2020 upgrade threads and now 2020A+ threads for a little while now. I have to say i find this thread quite interesting as im in a simular mind set, knowing i could buy better but enjoying the idea of fiddling with something cheap as a hobby type thing, which will also improve my little soldering skills.

    With that in mind i built some speaker cabinets a short while ago and bought an A+ with the intention of creating a portable PA system for garden parties etc. I however made the mistake of taking it to my Girlfriends house to show her my handywork and it got pilfered by her 10 year old son as new way to listen to their ageing TV...... at least i know it impressed him

    Either way, as i now didnt have an amp to play with i ordered a second A+ to modify while my original is at my partners house. On arrival i noticed that the new one sounded to me to have better clarity, which in a little bit of a blind test (them not knowing which was plugged in) my partner and her son both prefered the new one over the old. So i took the month old one home to play with and see if i could find a reason for its comparitive difference.

    once open i had a little look around and saw the usual array of parts pictured earlier in this thread and on others, but then noticed that C26 what seems to be a capacitor is missing on my board, but has traces of solder on the pads.

    So could C26 being missing cause a noticable audable difference, or could it be differences in other components? im interested to find out.

    the info in this thread has been brilliant so far, i wouldnt mind contributing as i go along and hope the thread continues beyond its current point

    cheers so far!
    phip
    Last edited by phipck; 09-26-2011 at 12:09 PM. Reason: sp*

  14. #54
    Join Date
    Aug 2011
    Location
    Annville, PA
    Posts
    22

    Default Re: Modding the Lepai T2020A+

    I did end up replacing my input coupling caps with some 2.2uF WIMA MKP polypropylene caps and the inductors with some 10mH ICE audio units. I think this little unit sounds great.

    I decided to stop using the built-in tone controls. The stock values must be off or something, it just doesn't sound right... it sounds just fine using the software EQ on my PC.

    I haven't attempted to upgrade the opamps yet but am thinking about trying out some Burr Brown units.

    And like yourself, this isn't bout saving money to me - it's about learning, tinkering, trying new things and gaining satisfaction. This little amp is a great springboard for those experiences.

  15. #55
    Join Date
    Sep 2005
    Location
    Reston, VA
    Posts
    2,184

    Default Re: Modding the Lepai T2020A+

    Quote Originally Posted by xoaphexox View Post
    I haven't attempted to upgrade the opamps yet but am thinking about trying out some Burr Brown units.
    Be careful about using opamps that draw too much current. Some of the high-end opamps draw a lot of current, and they might exceed what is available. I don't know what the power supply for the opamps looks like on the "A" version of the amp, but many times it is just a resistor and zener that is only good for a limited range of current. If someone can trace the circuitry for the opamp supply, I could tell you what the supply current limitations are.

    I usually recommend the TL082 as an upgrade for the 4558 because it is much higher quality (less distortion, much lower noise) and the supply current is about the same. But there are many other good alternatives.

  16. #56
    Join Date
    Aug 2011
    Location
    Annville, PA
    Posts
    22

    Default Re: Modding the Lepai T2020A+

    Thank you for that insight - I will do more research. In the vintage amps I have restored, I have replaced the old JRC 4558 with Burr Brown OPA2134 or OPA2604. Op amp 'rolling' can be fun considering how cheap they are.

  17. #57
    Join Date
    Jan 2006
    Location
    Sterling, CT
    Posts
    3,637
    Blog Entries
    3

    Default Re: Modding the Lepai T2020A+

    When replacing 4558's with better opamps like the OPA's and such you also have to worry about high frequency oscillation. You need to be able to check for it which requires an oscope and signal generator.

    - Another reason to just stick with the TL082 if you don't have the required measuring equipment.
    "I have not failed. I've just found 10,000 ways that won't work." Thomas A. Edison

  18. #58

    Default Re: Modding the Lepai T2020A+

    would the TLE2072 also be appropriate?

    It suggests compatable swaping with the 082 but improved noise etc

    http://www.ti.com/product/tle2072&lp...native_Devices

  19. #59

    Default Re: Modding the Lepai T2020A+

    Quote Originally Posted by gychang View Post
    sorry, I know that, what I meant was to get rid of (remove) the tone control circuit on permanent basis...

    I was messing around an broke the tone button on my Lepai. I started messing around inside. I took the pushbutton off and was able to jump the the points to complete the "direct" circuit. The switch is DPDT and basically acts to select one path or the other. I plan to remove the pots and create jumpers if needed.

  20. #60
    Join Date
    Sep 2011
    Location
    Rochester, NY
    Posts
    175

    Default Re: Modding the Lepai T2020A+

    Excellent thread guys. Thanks for all the information and tutorial. Truly a lot of great stuff. I ordered a TA2020+ and when I got it, the sound cut in and out any time you moved the input chords even a little. PE sent me a new one no questions asked which is quite amazing. The guy I did talk to stated that they don't have too many problems, though they do have a couple of calls for defects. Not surprising with how many units they must move of these guys at these low prices.

    Anyway, I ordered all the right stuff from Mouser and opened up the original unit yesterday to see if I could figure out why the sound was cutting out and to upgrade all the caps and other items... Turns out the ground was loose at the back of the unit where the RCA jacks are on the board. Looks like a really weak point, so if you have any issues with sound cutting out, that's a good place to look.

    Before I upgraded the parts, the TA2020 sounded great. After I upgraded the parts, it sounded AWESOME. Interestingly, I tested the unit after replacing the output caps and didn't notice too much difference in the sound. After replacing the input caps, the unit really was awesome. No hissing from the speakers regardless of volume. Really good bass especially all through the spectrum and at all volumes. It really did make a noticable difference.

    One point though - make sure you turn on the unit after using and after unplugging it to get rid of any charge. I didn't do that and saw a couple of sparks while I was replacing the input caps. Doh. Lesson learned.

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