Tube Head help

[jasonober]

about two months ago i retubed my sovtek mig 100 with 6L6s from bob at

http://eurotubes.com/index.htm

 and biased them at 39ma per his instructions to bias between 38-42   everything was GOOD! until yesterday when my amp started making this gated/compressed kind of sound going into the sound of guitar still sustaining for that short period while your amp powers down after turning it off     this most often happened when i easesd off on picking attack or rolled off volume at guitar.     So today i'm trying to debug problem at I put bias probe on the amp   my tubes are both reading 11ma (+/-  .15ma)    do new tubes settle this much and just need to be rebiased or is this indicative of a bigger problem?      thanks for any suggestions[/url]

[WorkBench]

Your new tubes should not settle at all as far as I know!  Sounds like a problem somewhere else.  Go to www.Hoffmanamps.com  The guys their will set you straight.  Not that someone here couldn't, I am just making a reccomendation! Good Luck.
Chris

[aron]

CHeck out this link:

http://geofex.com/ampdbug/distort.htm

One thing to do when you have it working and biased is to measure the bias voltage to the tubes. That way if you ever have problems, you can test that voltage to see if it looks ok. Sometimes the schematic will indicate a negative bias voltage (if it's fixed bias).

Could be a leaky coupling capacitor I guess as well. Did you add a bias adjustment or?

[jasonober]

I didn't have to add a bias adjustment  it has an adjustable final bias pot which meant so i  matched tubes and and took bias adjustment on each tube with this
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=43375&item=3737869679&rd=1&ssPageName=WDVW

so from what i'm able to understand i either have problems with the main capacitors or transformer      I guess it's time to go to the doctor
now all i have to do is find a good repairman in cincinnati

[BIGROCKSHOW]

Hope you get it straightened out.

[jasonober]

Is there any way that i can test the transformer and filter caps to start to diagnose my poblem before going to the amp doctor     I've removed chassis from cabinet and drained the caps      Don't see anything that looks unusual or different from what it looked like when last out of cabinet when biasing for new tubes