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Class D Switching Power Amplifiers and Power D/A conversion

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Old 8th March 2013, 03:15 AM   #91
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Quote:
Originally Posted by lwj5 View Post
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
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Old 8th March 2013, 04:59 AM   #92
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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.
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Old 8th March 2013, 05:41 AM   #93
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Originally Posted by Ford Prefect View Post
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...020avolpot.jpg
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Old 8th March 2013, 04:04 PM   #94
aj982 is offline aj982  United States
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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.
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Old 8th March 2013, 05:24 PM   #95
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Originally Posted by aj982 View Post
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..
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Old 8th March 2013, 08:49 PM   #96
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Originally Posted by tp4tissue View Post
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+).
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Old 8th March 2013, 08:54 PM   #97
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Originally Posted by tp4tissue View Post
----- 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.
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Old 8th March 2013, 09:35 PM   #98
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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.

Last edited by tp4tissue; 8th March 2013 at 09:42 PM.
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Old 8th March 2013, 09:41 PM   #99
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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.
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Old 8th March 2013, 11:50 PM   #100
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Originally Posted by Redshift187 View Post
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

Last edited by tp4tissue; 8th March 2013 at 11:55 PM.
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