LP-2020A+ mod thread

[tp4tissue]

What up Dudes:

Just got my Lepai 2 days ago.. I only had some lm4562s opamps on hand. So that was my only mod so far.

The sound is MUCH cleaner... so much so... that I'm wondering if I should bypass the opamps at all since the Tone-defeat button seems to bypass the tone controls.. I think my opamps are fine.

I am an expert on ghetto replacement of SMDs with total crap equipment

Does anyone know if I could use REGULAR polarized capacitors for C20 and C21, because I don't have any bi-polars on hand..


Picture of my board attached, It seems they went even more cheapo on components

Look at the dinky inductors this time around...

And they went for a ghetto dual power relay
--- Not sure if this portion greatly affects sound... maybe some experts could chime in...

 

[aj982]

I've been messing around with these as well. I found out the hard way that C20 & C21 can not be polarized. I made this mistake on my first mod attempt. Since then, I have learned a great deal about these things. I didn't kill my amp but it took me 3 days to figure out why it sounded like crap.

Now I have 2 lp2020a+ amps. One of them came like yours but with a single relay and the other came witg better components; they both look like salvaged parts. They will both be modded; one with all tone controls wiped, audio grade caps and ferrite core inductors all around. The other will have only upgraded caps. I'll post pics when I finish. Still waiting for parts.

 

[tp4tissue]

Hey aj982, sup

Thanks for the information on the polar caps.. I will have to find some nichi-es to replace them.. kinda hard..

You see those transistors in the Power Path?

I hate "muting" transistors in the signal path,

This irrational hatred also translates to transistors in general, because cheap ones always seem to introduce a great deal of "sssssssss--- noise"

Do you have any idea how to bypass these transistors...


Also are the opamps only necessary for tone and volume?

 

[danzz]

Hi tp4tissue

Yes the opamps are necessary for tone control and volume, If you bypass you Will loose the volume and tone control.

I did the exactly same mod upgraded the opamps for 4562s, as I didnt want to loose the tone control, also modded the output inductors with coils and the output caps with same value but from wima... And also changed the input cap for a 4700uf from Panasonic. With this modes I use it to drive a país of Overnight sensations and Im very happy with it...

 

[xrk971]

Hey xrk!

I'm going to cobble together something similar, except I plan to build an ultra-low budget hybrid integrated (tube pre and 2020 power).

I already own a 2020 and I have ordered a $21 "YJ" single 6N3 pre-amp kit, some switches and other small parts, an $8 power supply, etc. About $33 in total. Going to bypass the volume control on the 2020 (already bypassed the tone and opamp) to turn it into a straight power amp and then wire the pre-amp directly to the 2020. Stick it all in a homemade chassis and maybe even integrate a USB DAC.

I don't expect it to challenge an expensive amp, but it'll be fun as hell to build!

Is this project complete and now appears as that amp with the two open windows where the vu meters used to be in the photo of your Castles and amp in front of the window with mountain view?

An externally hosted image should be here but it was not working when we last tested it.

 

[tp4tissue]

Hi tp4tissue

Yes the opamps are necessary for tone control and volume, If you bypass you Will loose the volume and tone control.

I did the exactly same mod upgraded the opamps for 4562s, as I didnt want to loose the tone control, also modded the output inductors with coils and the output caps with same value but from wima... And also changed the input cap for a 4700uf from Panasonic. With this modes I use it to drive a país of Overnight sensations and Im very happy with it...

hello hello hello

Question... is there a difference between "high pulse" and "general purpose" wima capacitors

I am thinking of replacing the 6 output for .22uf Wima

---as a post suggested .22uf would give better bass.. I am using 6ohm speakers

and

the two "input" C20, 21 for 2.2uf Wima

__until such a time when 2.2uf nichicon es comes back instock at mouser
__unless you guys know of another trusted place with 2.2uf nichi-es

 

[aj982]

I saw a post that showed how to disable all tone controls and enable the volume control. This bypassed all opamps. I don't know how to bypass the transistors but I don't think they are an issue with this amp. I haven't heard of anyone bypassing those or needing to.

Hey aj982, sup

Thanks for the information on the polar caps.. I will have to find some nichi-es to replace them.. kinda hard..

You see those transistors in the Power Path?

I hate "muting" transistors in the signal path,

This irrational hatred also translates to transistors in general, because cheap ones always seem to introduce a great deal of "sssssssss--- noise"

Do you have any idea how to bypass these transistors...


Also are the opamps only necessary for tone and volume?

 

[cogitech]

Is this project complete and now appears as that amp with the two open windows where the vu meters used to be in the photo of your Castles and amp in front of the window with mountain view?

Hi XRK,

No, the 2020 + tube pre-amp project is still in the works and is intended for my bedroom setup. In fact, I just received a few of the parts I need for that project and I am very much looking forward to it.

What you see in that photo is my Shuguang I-25 tube amp and one of my dual EL70 microTowers. The windows in the amp are there so one can enjoy the tube glow better. Some vu meters would be cool, though. Perhaps another project there for me... The only modification I have made to the I-25 is to add a supplementary, higher amperage filament transformer so I can run 12BH7 tubes in the 12AU7 sockets. The 12BH7s draw 2x the amperage, and sound a great deal better doing so. Oh, I also strapped a heat sink to the power transformer and modified the rear cage to fit over it. I do plan to put new coupling caps in the I-25 as well...

 

[cogitech]

I am thinking of replacing the 6 output for .22uf Wima

---as a post suggested .22uf would give better bass.. I am using 6ohm speakers

I chose to do the same, based on the details in the TA2020 whitepaper. In there they specify all .22uF for 8 ohm loads and a combination of .47uF and .22uF for 4 ohm loads. My 2020B has all ******* .47s, and my speakers are 8 ohms. Not ideal, in the least.

and

the two "input" C20, 21 for 2.2uf Wima

__until such a time when 2.2uf nichicon es comes back instock at mouser
__unless you guys know of another trusted place with 2.2uf nichi-es

I got some NOS 2.2uF Roederstein Gold bipolars off ebay for the input coupling. They sound great. Anything is better than the stock crap.

 

[tp4tissue]

I chose to do the same, based on the details in the TA2020 whitepaper. In there they specify all .22uF for 8 ohm loads and a combination of .47uF and .22uF for 4 ohm loads. My 2020B has all ******* .47s, and my speakers are 8 ohms. Not ideal, in the least.



I got some NOS 2.2uF Roederstein Gold bipolars off ebay for the input coupling. They sound great. Anything is better than the stock crap.

Yea, my situation is even less ideal than urs according to the paper, as I have 6ohm speakars , since the datasheet doesn't detail what equation they're going by with the output caps.


I also chose to replace the 2x .01uf bipolar ceramic Cap in the output circuit with Wimas, LOL they were only 81 cents each, so i figured, F... it

I didn't even see them until I saw the datasheet... I honestly don't trust the SMDs they put in there.. because I have some "hissssss" goin' on, I'd like to put as much good high freq noise filtering in there as possible...

You can see the 0.01uf speced caps on the data sheet.. they are right above the inductors on the lepai board

Picture with cap circled below'

Another question... if I bypass the opamps//tone//volume

----- DO I need to remove all of those components? because I feel like if I did not, they would be erroneously grounding something in the signal path?

----- This leads to the issue, it is quite tricky to remove those things, confusing traces...

 

[tp4tissue]

Oh no I was trying to change parts C42, I thought it was a 0.1uF cap... now that channel became a low-pass filter or high-pass filter.

Anyone know the correct capacitance for C42 and C43.

Just to check C31 and C30 are 2.2uF right?

NO.. I don't believe 31 and 30 are 2.2 the input caps that specs 2.2 on the data sheet applies to 20 and 21,, NOT 31 and 30

 

[Ford Prefect]

I'm trying to replace the volume pot and mount the new one on the outside of my boombox, with the amp enclosed inside the boombox. Do I just remove the pot from the board and and run 6 leads to the new pot from the board? and what about the wire that runs from the top of the pot into the unpathed board? thanks from a newb.

 

[tp4tissue]

I'm trying to replace the volume pot and mount the new one on the outside of my boombox, with the amp enclosed inside the boombox. Do I just remove the pot from the board and and run 6 leads to the new pot from the board? and what about the wire that runs from the top of the pot into the unpathed board? thanks from a newb.

You "could".... but assuming you have a good "preamp" source

You aught to do the mod where it engages the pot "after" the bypass mod

pictured below

http://i9.photobucket.com/albums/a83/vulturex/lp2020avolpot.jpg

 

[aj982]

tp4tissue: I was afraid to get rid of all the tone controls but its easier than you think. I'll put up some info w/ pics very soon with detailed info on what I did. I tested it a little last night and it sounds excellent. It's a Frankenstein tho. You'll see what I mean when I post pics. People say that the tone control stuff still interacts even if you bypass so I just wipe it all.

Ford Perfect: I followed the picture in the link above. I will also show how I did this in my pics. I found a pretty clever way to do it.

My little lepai sounds awesome and has zero turn on pop.

 

[tp4tissue]

tp4tissue: I was afraid to get rid of all the tone controls but its easier than you think. I'll put up some info w/ pics very soon with detailed info on what I did. I tested it a little last night and it sounds excellent. It's a Frankenstein tho. You'll see what I mean when I post pics. People say that the tone control stuff still interacts even if you bypass so I just wipe it all.

Ford Perfect: I followed the picture in the link above. I will also show how I did this in my pics. I found a pretty clever way to do it.

My little lepai sounds awesome and has zero turn on pop.

Hey AJ, Thanks for the great info.. I am very interested in how to clean-wipe the opamp and tone..

As for how "it'll all look", I'm testing mine at the moment with placements and such, but yea,, I didn't read the Dimensions' portion of the wimas before I bought them...

NOT sure if I could fit everything inside the case..

 

[Redshift187]

I am thinking of replacing the 6 output for .22uf Wima

---as a post suggested .22uf would give better bass..

This isn't the case, it'll have no effect on bass at all. It affects only the frequency where the high end is rolled off, ideally between audio frequency (20khz) and the carrier frequency (100khz+).

 

[Redshift187]

----- DO I need to remove all of those components? because I feel like if I did not, they would be erroneously grounding something in the signal path?

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.

 

[tp4tissue]

Hi RedShift, thanks for chime-in'n on the details

I notice your pictures use BIG caps for C14 and C3... Is there a particular reason for this, or were those just the ones you had on hand..


Also, does the Power Relay affect sound quality? Mine are def salvaged parts, so, I'd like to know If I should get an Omron or something.

 

[Redshift187]

C3 is 470uF and C14,C15 are 180uF. They are bigger because of higher voltage, simply because I wanted the to use Panasonic FR series, which are great electrolytics.

 

[tp4tissue]

C3 is 470uF and C14,C15 are 180uF. They are bigger because of higher voltage, simply because I wanted the to use Panasonic FR series, which are great electrolytics.

I c...

What's your opinion on nichi- FG and KZ..

They were the only caps under "audio-capacitor" at mouser..

And someone on some forum said elna sux... so...

Since I'm a noob.. I just clicked through the smart filter like an I-Sheep.

What is the difference between panasonic FR FC FM I read the sheet, they're pretty similar..


Oh and yea... power relay.. anyone?? does the power relay in the output affect sound quality??

ALSO,, should I use 2 bypass capacitors, because I only have 2 x 0.22uf instead of 1 x .47uf capacitors.. my main power cap is a 4700uf 16v nichicon FG

dis' one guy said you need bypass caps of 1/10000th of the rated cap