I got this used and the serial number is barely visible. I removed the chassis and it has 10/25/06 date and tested by SMJ or SMI. I believe that the serial number read: BC060460. It seems to be a little lacking and it has JJ tubes, the rectifier tube is electro harmonix made in Russia. It makes noise when starts up. I am wondering if I need to send this in for a recap and complete go over.
Hi @Jevanski and welcome to the forum,
It looks very clean inside; I don’t see anything that worries me. I think you just want to get it back to factory specification and have it checked out? Fryette does not typically change capacitors, only if they are failing. Sounds like your unit just needs a re-tube and it will be back to life.
Follow these instructions to arrange to have it sent home.
Or you can send this in for a service if you want or a local tech can read more about that here,
By the way, the letters are SMF = Steven M. Fryette ![]()
Thank you for the great information. I will order new tubes. I have biased every other amp that I have owned and I could not find any information on how to bias this one. Could you send me the info on it please?
Much appreciated.
Hi Dan, can you send me the bias procedure for it please?
Check out Steve serving “your” amp here, at 27m50s
The whole video might be useful to you. It’s -34V on the grids.
I don’t have the service manual for this amp. Dave might chime in if he sees this!
for the current mullards I have in my mid 90’s 50cl the control grids are at around -40 V… it’s going to depend on the transconductance which varies per tube.
I don’t have a step by step instructions but my general procedure is one which sets the idle plate dissipation to a specific percentage (usually 70-75%, but lower is also okay) of the tube’s max plate dissipation (25 W). with the amp off, measure the DC resistance of each tap of the OT primary (i.e. measure the resistance from B+ to the anode of each tube, one at a time). turn the amp on. measure the DC voltage drop across each OT tap, divide by the OT resistance to get the idle plate currents for each tube. multiple the plate current by the plate voltage to get the idle plate dissipation in watts. divide this by 25 watts (for EL34) to get the idle plate dissipation as a percentage of max. adjust grid bias to achieve your desired idle plate dissipation.
if you have a sig gen, scope, dummy load, it’s then a good idea to use those to test the biased amplifier when it’s operating at full power. I think the UL biasing instructions go over that pretty well.
oh yeah, MAKE SURE the amplifier is in CLASS AB mode. Also I always do the bias procedure in ENHANCE mode (or AUTO mode in the green channel).







