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Commercial Gainclone kit- building instructions

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#2,221
Hello!

I decided to redone everything - from scratch!
Here is my link with the new pictures
all contacts are crimped or tied, then soldered
I made some room between the parts
Album photos GC LM3875-Tocos version - Casimages.com

Peter, does it make a difference a GC point by point or with your boards, with such a tiny circuit? franckly, it is hard to believe, but I learned, doing these GCs

so far so good, it sounds much better and measures well
the big caps are Supertechs, 10 000uF each
prp resistors are sweet, but somehow to much in the soft side for me,,,
I'll make a long check next, let's see if it plays music for hours, without issues

next steps, to put it in a nice box, to make my final gainclone and finally to assemble a serious classA amp,,,
 
#2,223
Yes Peter, I agree, I'll use boards
I know all those links, of course, since a long time ago
I had all 47labs, 18 years ago,,,
One day I saw a GC like the gaincard, (but silver), in Toronto, near Rob's hifi shop,,,
it doesn't exist anymore with all those turntables

Anyway, thanks for the help
it seams that the mystery is gone

BTW,

It's been a few hours that the amps are playing without issues!
 
#2,224
I would like to try the Belleson Superregs between the output psu and pins 1 and 4 of the LM3875
does it makes sense??
it should work!

a good regulator will block power line ripple from the speakers and provide a more stable supply voltage when current is required quickly by the load.

Maybe I can hear improvement with a monolithic regulator, then I'll replace it with a Superpower, it will be even better.
what do you say?
 
#2,234
I finished my build yesterday and one of the large capacitors emitted lots of grey smoke, any suggestions on easy to source decent capacitors to replace all 4 with? I'm in the UK if that helps.

I'm using a 24v + 24v/400va toroidal transformer, when I tested to psu it gave 27.5v output. Is this too high?

I borrowed a Variac and didn't think to test the output of it for different dial positions, will do this before connecting again.
 
#2,236
With 16V transformer you will get less power as per attached graph (after rectification it will be approx 23V DC)
Also, the amp will lower rails will sound less dynamic and more mellow.
 

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#2,239
After the period of absence, the website is up and running again: Audiosector

The manual can be downloaded here: Manual

I also put all my major projects in one place: Projects – Audiosector

Presently, only LM3875 kit (Classic and Premium version) is available, this section of a website is still under construction but you can order it directly through me.
 
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#2,240
How to balance bias currents for Audio Sector LM3875 with reduced gain?

Hi,

I'm building new Audiosector LM3875 mono blocks and this time I want to reduce the gain by making R3=1K (se picture). My question is; How do I balance the bias currents properly, should R1 = R3||RF? Should R2 play into the bias balancing somehow?

/M
 

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