VH4 PLATE VOLTAGE

  • Thread starter Thread starter smdb
  • Start date Start date
Then you have just 220V prim I guess. Always 480V here, Pit.
 
oh hell.....disregard :doh:

i had just got done buttoning up my Uberschall and rebiased / retubed it. had 580V on the brain :confused:

this is your brain on drugs :rock:
 
Peter, Olaf or anybody who knows..
I put a set of Siemens N.O.S el34 tubes in my vh4, my buddy told me that he thought the plate voltage was too high for these tubes. I was told that the plate voltage should not exceed 450 for these tubes. Is this True? Will it ruin the tubes quickly if it is higher than 450?
Thanks,
Steve
 
Hi Steve,

those Siemens (do they have a dimple top? then they are originally made by RFT in eastern germany - Siemens never produced EL34s themselves, just bought off EI and RFT, sometimes even Telefunken or one of the Phillips sites) like any other EL34 can - per specs - handle 800 Volts at their plates.
The limiting value are the screen volts. Inside Diezels thats 460-470 Volts or so, which they should handle fine.
Those tubes have slim bass and do sound very good.

On the other hand: I wouldn't use NOS EL34s in any other amp than a vintage Marshall or Hiwatt (or similar). The poweramp in modern amps is made to be "neutral" and not "overdriven" (like in a vintage Marshall) - in vintage amps they shine, in modern amps (well, just my personal opinion), they are wasted. Use a good Svet or chinese or (to speak with Peter) EL34L or a Teslovak and safe them NOS things for vintage amps.


Typical dimple top RFT:
RFT-Delle.jpg


typical Siemens-RFT EL34:
RFT-Siemens-EL34.jpg


and a Siemens made in Jugoslavia (EI)
Siemens-EL34-Jugosl.jpg
 
Olaf, They are the Mesa boogie NOS el34 str, They sounded friggin great!!! I was kinda shocked at the gig last week. I blew a set of winged c's the week before after only a few months,(i was not liking them too much anyway, kinda muddy) so I installed the vintage tubes right before the gig this past weekend. I noticed the slimmer bass but damn.. they sounded good. :rock:
So these are kinda wasted in the Diezel??
Thanks for the help
Steve
 
I have a nice collection of NOS tubes myself, but I refuse to put them into my own stuff or my Diezels, just because they are getting harder to find, you know . . . RFT (or "Siemens" as they are uncorrectly called mostly in the US), Telefunken and Mullard/Valvo were the best stuff money could buy - and nobody today comes close to them . . .

If you have a good, reliable and not too expensive source: use them of course, they are awesome. Just don't bias them that high so they will stay healthy for a long time.
 
Yeah, they are tough to find and very high $$$$.
What would you bias them at? I set them at about 34 w/ the the Weber Bias Rite..
 
30mA when reading the cathode current (what the bias rite does).
Try if you can live with that.
If not: 33mA max . . .
 
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