GoodSoundClub - Romy the Cat's Audio Site

In the Forum: Melquiades Amplifier
In the Thread: A different breed of 6C33C amplifier.

Post Subject: It's OK for now.Posted by KOTriode on: 11/2/2011

I used those VPI magic brick sitting on top of the transformer, my audio analyzer tell me that these bricks helped the noise by about 1db, may be the 6 lbs or so weight does damp the xformer vibration, so I leave them on, just trying everything to keep the hum low.
You have a good point about changing the position of the toroidal, I have thought about standing it up, but the wire I cut was too short to move the transformer. The hum from magnetic field must be pretty high from these toroidal, because when I remove the can and the toroidal is exposed naked, the hum was higher by 3db!
For now, the hum level is slightly audible, good enough for me to go on and compare the 6C33C preamp sonic to other. Onto the 6C33C amp, on my second set of tube (not the golden grid), which has about 50 hrs of playing in the amp, are pretty stable now, the bias current reach to the exact 200ma setting after about 15 minutes every time, so far no surprise.... I never have problem with hum in this amp, I guess with the step down ratio of 600:4, it is not sensitive as the preamp 1:1 in therm of noise and magnetic field.

Rerurn to Romy the Cat's Site