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Tube DIY Asylum Do It Yourself (DIY) paradise for tube and SET project builders. |
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In Reply to: Re: 400k resistor on 300B grid??? posted by MaciekP on January 20, 2005 at 09:26:56:
Hi,> It is probably true for WE300B tubes.
I found it true with Svetlana, Sovtek & Shuang and TJ as well. I have operated these previously with very high value Gridleak resistors.
> Most current production 300B have the limit
> of 50k with fixed bias and 100k with autobias
> (look at AVVT, EML etc datasheets).AVVT/EAT/EML are valves I rarely get my hands on. Moreover, they are strictly speaking not 300B's, but something rather different.
> Everything is fine if you have the the sensitive speakers
> and don't drive 300B amplifier to hard.Note, there is a crucial thing with the WE 310A Pentode driver. You CANNOT drive the Valve hard. There is no current available to drive it.
> Can you tell me why high Rp pentodes can't work with grid choke?
Simple, a 91K source impedance into a 1,500H//50p Gridchoke is not conductive to getting any reasonable bandwidth out of the amplifier. You end up around 1db down at 20hz & 5KHz each.
You must understand that pentodes and triodes are totally different and what serves one well is not usefull to the other.
Ciao T
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Follow Ups
- Re: 400k resistor on 300B grid??? - Thorsten 01/20/0510:14:16 01/20/05 (1)
- Re: 400k resistor on 300B grid??? - MaciekP 02:14:08 01/21/05 (0)
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