I finished assembling this in January, and with the limited time I have to work with it, it took awhile to fix my problems.
When I first turned it on I found noise was a problem. It was reading 36db below full scale, plugged straight into a Delta 44. So I applied for a building permit to lower the noise floor. I found the PS was under filtered, so I added a couple capacitors in the first stages of the PS. This gained me 6db. After Checking everything I could, I suspected the heater supply was the source. After building a DC PS for the heaters The noise was gone.
Even with the noise channel 1 sounded great, without the noise CH1 sounded GREAT. Everything I hoped for and more.
CH2 on the other hand was a little too dark for my taste. It also had what I can only describe as a bump about every 3 seconds. I went through the circuits with a fine tooth comb, and could not find the cause. The thing is it never showed up on the scope. I only get an hour or two a week in the studio to work so it took a month to find the problem. One day it dawned on me to put the scope on the secondary of the OT. And there it was, my elusive bump. At this point I knew it had to be coming from the Buffer for the VU meter. The buffer was tucked in behind the low voltage PS. So I unsoldered it and the picture tells the rest of the story.
When I first turned it on I found noise was a problem. It was reading 36db below full scale, plugged straight into a Delta 44. So I applied for a building permit to lower the noise floor. I found the PS was under filtered, so I added a couple capacitors in the first stages of the PS. This gained me 6db. After Checking everything I could, I suspected the heater supply was the source. After building a DC PS for the heaters The noise was gone.
Even with the noise channel 1 sounded great, without the noise CH1 sounded GREAT. Everything I hoped for and more.
CH2 on the other hand was a little too dark for my taste. It also had what I can only describe as a bump about every 3 seconds. I went through the circuits with a fine tooth comb, and could not find the cause. The thing is it never showed up on the scope. I only get an hour or two a week in the studio to work so it took a month to find the problem. One day it dawned on me to put the scope on the secondary of the OT. And there it was, my elusive bump. At this point I knew it had to be coming from the Buffer for the VU meter. The buffer was tucked in behind the low voltage PS. So I unsoldered it and the picture tells the rest of the story.