Bogner Shiva Bias

[scottbaierl]

I have an earlier Bogner Shiva EL34, with the brushed silver back. I re-tubed and needed to bias the amp so I got a hold of Charley at Bogner, and he indicated that the bias should be set to 29 ma. He also said that you need to check the bias when the tubes are real hot, or you won't get good readings. He suggested playing the heck out of them first, then hookup your probes, and check the values. I asked him which tubes to use, and he said you should use the SED winged C tubes. Apparently, they are the original Svetlana tubes. New Svetlana tubes are actually made by Electro Harmonix. He said you can use any good EL34 tube, but they may not last as long as the SED winged C tubes. For what it's worth, the guy that had my amp before me had JJ's in it and they worked fine.

 

[RockStarNick]

Everything in this post is 100% what Charlie told me too.

The Shiva has bias drift when you crank it.

Many people think that the Shiva's are biased cold, then they bias them hot, and blow tubes when they crank it.

 

[richedie]

All amps have bias drift when you crank them.
I have mine set at idle right now to 36.
I had a conversation with Charlie and he was finally understanding the truth after while. Heck, my VHT bias used to hit 70+ at times when cranked. It is the nature of tube amps to drift.

I have been running mine at 36 for over a year. Last night I set my Shiva and PWE to 30. I don't hear or feel a difference whether at 30 or 30 so I figure leave it lower to allow the tubes to last longer.

 

[fishyfishfish]

+1 You don't want Shiva at 70% when cold or un played. This was an expensive lesson for me. Last time I checked my amp was at 23 mA and sounded fine at normal gig levels.

 

[djpatb]

Sorry to bump this from the dead...but does anyone know where an EL34 Shiva should be set at idle with the volume down?
Mine is reading 18ma...when I play through the amp to get the tubes working, it shoots up to a high of 75ma!
This is a strange beast.