Will a Shiva fry a pair of Siemens EL 34s?

I am no exspert, but I belive the Siemens to like a Lower Voltage. My Shiva has 500+ V on the Plates.

 

It's a little strange based on what Bogner's own manual says.

From the Shiva manual:
http://www.bogneramplification.com/ShivaManual.htm


"3. Tubes

EL34's should be only Svetlana or old stock Siemens/Telefunken/Mullard. Other brands may work but it's risky because of the high plate voltage we use."


My understanding of the Siemens is that they shouldn't be used in amps with plate voltage over 450 volts. If the Shiva is higher than 450, I'd avoid the Siemens regardless of what the Bogner manual says.

 

I bought a few Siemens el-34s from mike @ KCA a few months ago for a Marshall and he cautioned me about high plate voltages with these. There must be something to it as Mike is generally well-regarded for his tube knowledge and advice.

 

When Reinhold forst started production of the Xtcy, he ALWAYS used Siemens 34's... for the first few years, until he could no longer get a good supply. They all (Ecstacys) run around the 500 mark. I've always used them in my Xtcy's and NEVER once had any problems.

 

I was gonna say i still use some Siemens 34s in my Plexi I pulled out of my old 100B.

 

Yep!!
Great tubes, Ed!!
I've never had one die in 20 years of using them in about everything I've ever owned.
keith

 

I love 'em. Sheet...the ones in my plexi have been in that amp since about 5 years...and had already been in the 100B 2 years prior.

 

Yep I"ve used Siemens in my Orange or120 head that runs about 500volts and never had a problem despite all the warnings I got!!

eRIC

 

What's with all the warnings anyway?
They seem fine in any amp I've ever used them in...

 

My understanding comes from Mike at KCA, and I assumed he was referring to RFT/Siemens.

 

I'm assuming that you haven't tried more than a handful of these tubes in your various amps. It's always possible to get lucky. Some tubes will beat the odds.

Even if only 10 to 20% (which would be optimistic) would fail in amps with plate voltage over 450V, it would be pretty lame to recommend them for such applications knowing this fact.

 

SEDs, GT 6CA7GEs or Mullards (which are VERY pricey).

 

Mike - Speaking of the GT 6CA7GE's, I was wondering if you had any observations on properly biasing these tubes. Some resources I've seen say that they should be treated as EL34's for biasing purposes. Groove Tubes, however, (or at least Myles) says that they should be biased more like 6L6's or in between 6L6's and 6550's. This would result in a significantly warmer bias setting, if I'm doing the math correctly.

I have a Rivera Fandango that I'm using them with, and it runs about 455 volts usually, for reference. Thanks for any insight!

 

Well...I guess I've been quite lucky. I have owned 5 Bogners in the last 14 years and every Marshall 100 watter I've owned/own has Siemens 34's in it, some of them are real old amps with plate voltage pushing 550...
NEVER once have I EVER had one problem!

Keith

 

Hey Mike,

Why would Reinhold use that tube in all his amps if they were not safe over the 450 mark? (most Bogners are around 500)
I do believe this "450" thing, not at all that I doubt you, as I've read it in many places... I just wonder why he would do that?

Take care,
Keith

 

I've seen Seimens run forever at real high voltages and I've also seen three of them blow within a couple minutes at around 500 volts from personal experience. If they are gonna go they will go pretty quick. Bogner may be running 150k bias resistors between the PI and out put tubes or may have a high value screen resistors in his amps, both of which will help. They are nice sounding tubes but Mike K. is right about them.

 

Oh I believe him, Mark.
I just don't understand why a guy like Bogner would use that specific tube (while he had a good supply) in ALL of his amps ... That's all.

keith

 

I used them in my 67 plexi SB with 560+ volts on the plates. They lasted 10 years and now I have a pair (from the 10 year old quad) in my JCM800 2204.