Express bias range
Moderators: pompeiisneaks, Colossal
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Randy Magee
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- Location: Leland, MS
Express bias range
Is it unusual to have to adjust the bias resistor to be able to get EL34s to the proper range? With the 47K resistor I couldn't get even 50% plate dissipation at idle. I had to drop the bias resistor down to 39K to get the proper range...
Randy Magee
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martin manning
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Re: Express bias range
What value is the resistor coming from the B+ to the bias supply?
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Randy Magee
- Posts: 222
- Joined: Thu Feb 16, 2006 12:05 pm
- Location: Leland, MS
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martin manning
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- Joined: Sun Jul 06, 2008 12:43 am
- Location: 39°06' N 84°30' W
Re: Express bias range
If your screen and plate voltages are reasonably in line then that particular set of EL34's just needs a little higher voltage to reach a given plate current.
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Randy Magee
- Posts: 222
- Joined: Thu Feb 16, 2006 12:05 pm
- Location: Leland, MS
Re: Express bias range
The plate voltage on both EL34s is 412 VDC... the screens are running 395 VDC... that seems pretty in line with what you'd expect... the strange thing is I have multiple tube sets that wouldn't get in range with the 47K R29 resistor... all's well that ends well, I suppose...
Last edited by Randy Magee on Mon Apr 16, 2012 11:32 pm, edited 1 time in total.
Randy Magee
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funkmeblue
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Re: Express bias range
couldn't you get more range by changing the 47k resistor to 22k and the 25k pot to 50k?
anything worth doing, is worth doing right
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Randy Magee
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Re: Express bias range
Probably, but I already had the 39K and that put me in the ballpark...funkmeblue wrote:couldn't you get more range by changing the 47k resistor to 22k and the 25k pot to 50k?
Randy Magee
Re: Express bias range
???Randy Magee wrote:The plate voltage on both EL34s is 312 VDC... the screens are running 395 VDC.
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Randy Magee
- Posts: 222
- Joined: Thu Feb 16, 2006 12:05 pm
- Location: Leland, MS
Re: Express bias range
Typo... the plates are running 412 VDC and the screens 395... doh!Firestorm wrote:???Randy Magee wrote:The plate voltage on both EL34s is 312 VDC... the screens are running 395 VDC.
Randy Magee