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Adding bigger caps to classic LM3875

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pbertino

Member
Joined 2013
I built a good sounding LM3875 classic with stock parts and 300VA 22/22 transformer.

I'd like to add a little oomph to the bass response.

I was thinking of adding 10,000 63v caps to the PSU. This is done at C1 and C2 on the board, correct?

Do I need to adjust/change any other components when adding these caps?

Thanks.
 
P

pbertino

Member
Joined 2013
Thanks for the pointers. I know this has been discussed a lot previously (years ago!).

I want to add a little to the low end without coloring the sound (much). According to your (Peter's) testing, the snubber changes the neutral tone of the amp.

I just ordered some Nichicon KG type I 10,000uF 63V. I'll try to alligator clip them to test the difference.

Maybe just adding a summing circuit and a powered subwoofer is a better choice.
Like page 42 (vol 14 #4)?https://community.klipsch.com/forums/storage/3/740089/DOPE%20from%20HOPE!!!.pdf
 
P

pbertino

Member
Joined 2013
Just an update that others may find helpful.

The 10,000uf Nichicons didn't seem to affect the bass, but some detail was definitely sucked out of the music. Maybe they weren't the ideal caps.

I removed them, then replaced the basic resistors with the ones from the premium kit (caddocks and riken).

Pronounced improvement in the clarity.

If you're looking at Audiosector LM3875 kits, don't skimp. Go for the premium kit.

I also added a small subwoofer to my bookshelf speaker setup and it works great to fill in those lower frequencies.
 
S

SimonKit

Member
Joined 2006
Hi Peter, hope all is well with you. Based on the discussion above I was wondering if this is still your opinion:
"I'm coming to conclusion that the less stored energy the amp is dealing with, the fresher the sound becomes".

And are you personally still using only 100u BG N near the amp and nothing at the bridges (different than in the Patek)?
 
jgwtriode

jgwtriode

Member
Joined 2012
Peter Daniel said:
Yes, this is still my opinion. However, I would be using BG N 100uF caps only at the chip if the amp was intended for mid or high section of multi amp setup. For full range BG STD 1000/50 at the rectifier are still needed.

If I'm not using BG caps, Panasonic FC 1500/50 are my first choice.
Click to expand...

Is there any advantage using 1500uf/50 vs 1000/100uf on the cap setup?

I am running Mundorf Mylitic AG+ 4 poles for the 1000uf caps on the PSU board and 100uf Panasonic Pureism XPL 100uf on the chip board?


jgwtriode
 
dimkasta

dimkasta

Member
Joined 2010
pbertino said:
Just an update that others may find helpful.

The 10,000uf Nichicons didn't seem to affect the bass, but some detail was definitely sucked out of the music. Maybe they weren't the ideal caps.

I removed them, then replaced the basic resistors with the ones from the premium kit (caddocks and riken).

Pronounced improvement in the clarity.

If you're looking at Audiosector LM3875 kits, don't skimp. Go for the premium kit.

I also added a small subwoofer to my bookshelf speaker setup and it works great to fill in those lower frequencies.
Click to expand...

If you want more bass and to keep the freshness, do not replace the caps. Keep the 1500uF on the main board, and put the 10000uF on the rectifier board. One for each rail. 4 for two channels

Like this

397386d1391371499-commercial-gainclone-kit-building-instructions-b3.jpg
 
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