LP-2020A+ mod thread - Page 11 - diyAudio
Go Back   Home > Forums > Amplifiers > Class D

Class D Switching Power Amplifiers and Power D/A conversion

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 9th March 2013, 12:03 AM   #101
diyAudio Member
 
Join Date: Aug 2008
My opinion is Panasonic FR I don't buy "audio" capacitors. I go for high ripple current and low ESR. FR are like the goodness of FM and FC in one.

The power relay isn't really necessary once you've gotten the "pop" to lessen, but I've never felt like I need to remove them from circuits.

The ideal output capacitors (which I assume you're talking about with those values) depend on the speaker impedance you'll be using.

If you really are talking bypass capacitors, I often use between 10uF and 100uF, sometimes bypassed with 0.1uF. In the case of this amp, I stayed pretty close to the values they provided, just with much better caps.
__________________
Tyler
  Reply With Quote
Old 9th March 2013, 01:39 AM   #102
Bare is offline Bare  Canada
diyAudio Member
 
Join Date: Dec 2001
Location: vancouver
Quote:
Originally Posted by Redshift187 View Post
If you look at post 6, I explained how to disconnect the opamp circuits from the rest of the circuit just by removing 2 resistors. You can leave them on the board if you want. They are already disconnected on one end by the tone/direct switch. If you remove the two resistors, they'll be completely disconnected.
No the truly crap Op amps are Not disconnected by the foolish Tone defeat switch. Which is Why, they at least, needs be physically removed.
Warm up your Iron and simply wipe them off the board.. It's fun :-)
Also counterproductive to insert Anything exotic beyond a Wima input cap. Leave the Hi $$ caps for other Amp designs.
Both your ears and your wallet will thank you.
  Reply With Quote
Old 9th March 2013, 01:52 AM   #103
diyAudio Member
 
Join Date: Aug 2008
Oh, my bad. The TONE op-amp is disconnected by the tone/direct switch. You can still easily remove them both from the circuit completely without physically removing them, and I've already detailed it.
__________________
Tyler
  Reply With Quote
Old 9th March 2013, 01:59 AM   #104
aj982 is offline aj982  United States
diyAudio Member
 
Join Date: Mar 2013
Ok, I finished my mods... With the exception of my MUSE input caps that are in the mail. I have some temp panasonics in there now.

Mods include:

Ferrite core inductors all around.
-Panasonic film caps for output.
-Relocated caps (the big ones, don't know what they are called) & inductor due to space limitations
-All tone controls wiped including bypass switch
-Volume pot rewired
-Install better thermal compound for heatsink
-Install 'better' rca inputs
-Removed annoying LEDs
-Removed 3.5mm input (will not be used)

I think that's about it. The first pics don't have the big caps in them just in case anyone wants to see all the tone control wipes.

If you have any questions, let me know. This thing sounds great. I love it and it was very fun working on it.

Thanks to all the contributors for your help and write-ups.
Attached Images
File Type: jpg IMG_0501_S.jpg (670.9 KB, 376 views)
File Type: jpg IMG_0503_S.jpg (566.8 KB, 352 views)
File Type: jpg IMG_0505_S.jpg (539.2 KB, 341 views)
File Type: jpg IMG_0509_S.jpg (757.4 KB, 335 views)
File Type: jpg IMG_0511_S.jpg (497.9 KB, 328 views)
File Type: jpg IMG_0513_S.jpg (546.3 KB, 172 views)
  Reply With Quote
Old 9th March 2013, 02:55 AM   #105
diyAudio Member
 
Join Date: Aug 2008
Really tidy work AJ! I suppose I should post some more photos, though it's not nearly as tidy as yours.
__________________
Tyler
  Reply With Quote
Old 9th March 2013, 03:08 AM   #106
diyAudio Member
 
Join Date: Aug 2008
The output section mods:

I replace the inductors with Wurth 10uH 4.7A inductors (note I put 2 of those in wrong, the dot should be on the side that the amp chip is on - backwards will increase EMI).

The small ceramic SMD cap I replaced with 0.01uF WIMA caps (the two holes are meant for larger filter caps, but was a perfect fit for 5mm lead spacing as long as the other two caps are also 5mm).

The four output filter caps next to the inductors I replaced with 0.47uF film caps as the originals were probably ceramic.

The inductors + 0.47uF caps + 4 ohm speakers should give a cutoff of about 73kHz (I wish I could find the spreadsheet I used for that calculation).

I replaced the zobel components with 6R8 and 0.22uF film caps to give a frequency point of 106kHz (it should be a little higher than the primary filter cutoff so it doesn't have to deal with a lot of energy).
Attached Images
File Type: jpg output_section.jpg (468.0 KB, 201 views)
__________________
Tyler
  Reply With Quote
Old 9th March 2013, 03:13 AM   #107
diyAudio Member
 
Join Date: Aug 2008
For anyone who is nervous about removing all the op-amp components, don't be. It doesn't matter one bit if you pull those traces off the board, and will give you some experience (removing them is much harder than soldering them in the first place). For the op-amps, I usually try to lie the soldering iron tip along all the pins on one side while gently prying up with a pin or tweezers. Once one side is lifted, hold the board on edge and heat the other side, the op-amp will fall off.

Everything in the green circle is fair game, as well as R18, R19, R20 and R21. Note that you WILL have to do more than that to have a functional amp, some sort of input bypass wiring, with or without the volume control.
Attached Images
File Type: jpg remove.jpg (318.9 KB, 211 views)
__________________
Tyler
  Reply With Quote
Old 9th March 2013, 03:40 AM   #108
diyAudio Member
 
Join Date: Mar 2013
To AJ and RedShift

This is some inspriational sh...t

like Alladin, rags to riches kinda dope

I wish my ugly duckling looked half as good as you guyes's'


AJ, are you just using the original volume pot? or did you use the tone pot.. it looks smaller to me.

Also, what are those rca "plugs" you guys bought called..

Last edited by tp4tissue; 9th March 2013 at 03:45 AM.
  Reply With Quote
Old 9th March 2013, 04:31 AM   #109
diyAudio Member
 
Join Date: Mar 2013
Question:

Did you keep C2, the blue circle..

and Is there any stuff underneath the wires circled in the Green that you removed or replaced?
Attached Images
File Type: jpg IMG_0509_S.jpg (760.7 KB, 204 views)
  Reply With Quote
Old 9th March 2013, 04:37 AM   #110
diyAudio Member
 
Join Date: Aug 2008
I kept C2.

I replace all electrolytics in the amp, some with film depending on the value. Nothing else under the green circle was changed.
__________________
Tyler

Last edited by Redshift187; 9th March 2013 at 04:44 AM.
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
TA2024 SA-36 or LP-2020A Terrymm Class D 3 28th September 2012 04:34 PM
Help with Lepai LP-2020a+ ChrisChris Class D 5 14th September 2012 03:24 PM
Lepai LP-2020A+ Balance Problem Nightcry7 Class D 3 14th September 2012 03:16 PM
Lepai LP-2020 mod to include sub out rziebro Class D 1 12th February 2011 03:01 PM
X-LP Mod Journey pjpoes Analogue Source 2 11th March 2007 07:35 AM


New To Site? Need Help?

All times are GMT. The time now is 07:47 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2