Amp Camp Amp - ACA

[stefanobilliani]

Originally Posted by Variac

One side the schematic I think , the other side a board outline with the parts outlines shown- like the board silkscreen layer, Then the list of parts underneath.

Wonderfuuuul!!!

[nicoch58]

Variac a NP pic on arm ?

[Variac]

with a halo!

[Loudthud]

I got a second channel up and running. On each channel I installed a 1K resistor from base to emitter of Q3 with a jumper so as to increase bias current to about 2.2 amps. For some reason the DC adjustments of the two channels interact even though separate power supplys were used for each channel. The output caps, C1 are still in place.

For this first test I just used the balanced in and out of the Audio Precision System 1. I'll try other ways of connecting a single ended signal source in a day or two.

[Variac]

Maybe they aren't interacting but there's heat drift?

[kikko]

I completed my ACA: Really good. i like it! It sounds really good and with an adequate level with the cdplayer, with the turntable i need a bit more gain.
but there is a little problem: is biased at 10V but is not heating up.. i can keep my hand on heatsinks indefinitely.
the heatsinks are hifi2000 model 3PD02200 (200mm*40*80) rated at 0,67c°/w. one channel is a bit warmer than the other one.
Is that all right? Thank you!

About the t-shirts.. i'll work on the file using forum suggestions tomorrow

[Loudthud]

Originally Posted by Variac

Maybe they aren't interacting but there's heat drift?

I think it was because I was using balanced floating drive. The time constant of C3 is about 4 seconds if the input doesn't have a path to ground. The problem dissappeared when I changed to balanced grounded drive.

[waam68]

Been working on these this week after work and finished wiring one up tonight. Seemed ok on a dummy load so I hooked it up and even on one channel sounds sweet. Still need to adjust the voltage, finish wiring up the second mono bloc, finish the cosmetics etc. I will post more thoughts when completed.
Mike

[waam68]

Another view

[overtheairbroadcast]

Originally Posted by waam68

Been working on these this week after work and finished wiring one up tonight. Seemed ok on a dummy load so I hooked it up and even on one channel sounds sweet. Still need to adjust the voltage, finish wiring up the second mono bloc, finish the cosmetics etc. I will post more thoughts when completed.
Mike

What I am interested in is what is it hooked up to as a power source? A block of iron and a tube rectifier? Look very hardcore power source wise...