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Old 20th July 2004, 10:20 PM   #1
Jean is offline Jean  United States
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Default My GC is up and running, side by side with P3A

So, it's been running on the bench for two days on and off w/o smoking. Today I fired it up with my speakers to hear how it sounds.

I have a very little hum in both channels, but that's most likely because I don't have Chassis Ground connected. I noticed that there is a loud turn off pop when AC is disconnected from the amplifier. Hum is only noticable with the ear next to the speaker when nothing is playing.

Next I tried to compare its sound side by side with my p3a amplifier on exact same speakers with exact same source. I even used same bridge diodes and upgraded input capicitors on the p3a with np 4.7uf black gates. p3a is using latest onsemi driver and output bjts.

It's really hard because I am not getting exact same output level between my p3a and my gc. So I had to adjust the volume every time I switched between the amplifiers. I also tried comparing by connecting left channel through p3a and right channel through the gc.

I can't really pin point anything drastic other than the volume. The only other thing that I believe is different, and I switched between the amplifiers about 8 times to make sure its not in my head, is the sound of the piano. It seems to me that ATTACK comes out faster and maybe even brighter out of the gc. What I am talking about is the sound of the piano keys. They sound more aggressive, not as mellow as with the p3a. Finally , sound stage with the gc seems to be more in focus than with the p3a.
I used Evanescene - fallen album, track "haunted" and "hello" to do this test and her voice comes right out the center with the GC, and it doesn't sound like that with the p3a.

Finally, my speakers aren't the easiest to drive and I could easily drive the gc into distortion unlike my p3a. Rail voltage on both is 36, with 25-0-25 toroids and mur860 diodes in both amplifiers.

This might change in a few days with more listening.
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Old 21st July 2004, 10:35 AM   #2
mAJORD is offline mAJORD  Australia
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Whats a "p3a"
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Old 21st July 2004, 10:38 AM   #3
Nisbeth is offline Nisbeth  Denmark
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P3A = Rod Elliot's Project 3A-amplifier from sound.westhost.com


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