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Old 17th July 2008, 06:08 PM   #111
sgerus is offline sgerus  United States
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Quote:
...what is the best tube to use as a driver?
That’s the million dollar question….

What input sensitivity do you need?

The 5842 needs about 2Vrms in to drive the 300B with the grid at -61V
The D3A is about half that… check the tube depot for this tube 7721=D3A

The 6C45PI is very close to the 5842, I think triode electronics sells the 6C45PI

The C3g is $$$, hard to find, and if I recall needs a special socket and a 10V heater
(check that out… I just going from memory)

I would start with the 5842 and see how it works for your needs…
Don’t expect to get it right the first time… you really have to experiment and see what works best with your music source(cd, mp3,preamp), speakers, and typical volume you listen at.
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Old 17th July 2008, 09:07 PM   #112
coresta is offline coresta  France
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Quote:
Originally posted by sgerus


The C3g is $$$, hard to find, and if I recall needs a special socket and a 10V heater
No! lots of them on ipé (even NOS TFK i found for 8 euros/ea !) heating : 6,3 volts , socket : loctal only ... (c3m is 20volts )

or less : http://cgi.ebay.de/2-neue-OVP-Roehren-C3g-Telefunken-mit-Goldpin_W0QQitemZ300240546475QQihZ020QQcategoryZ11 3447QQssPageNameZWDVWQQrdZ1QQcmdZViewItem Aber du musst zuerst auf deutsch über Versandkosten fragen
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Old 18th July 2008, 03:12 AM   #113
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It doesn't need to be all that sensitive since I am planing on using a line amplifier. Thanks for all the info, very good to know about the D3a, they seem inexpensive as the 7721. I just wasn't sure how the 6AN4 is sonics wise compared to some of these others.

Yeah the C3g is about the same price as the 5842 from where I can get it. It is just that it is loctal and it seems like the D3a would be a better choice.

Cheers

James
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Old 18th July 2008, 03:45 PM   #114
sgerus is offline sgerus  United States
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Quote:
It doesn't need to be all that sensitive since I am planing on using a line amplifier
Then try this first: 5842
175V @ plate
2.75V @ cathode, 250R, 11.2ma

I have tested this on my 2A3-40 amp... 1.44vrms in will drive the 300B (gird at -61V)

The 5842 also had the best frequency response of the 4-5 different input/drivers I tested
(I'm post the complete test results later)
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Old 24th July 2008, 07:27 AM   #115
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Hi People, my last 300B 76>6F8G>300B>
5Z3, over Derek Walton circuit or JE Labs with some modifications, I build some 300B, 6J5>10Y>300B, WE91, SRPP 6SL7, 6L6 or 6F6 as driver but I return of the JE LABS, IMHO the 76 is a great valve for the imput, 6F8G is a 6J5 in a twin triode valve, perhaps replace it with another Triode such a 6AH4, the amplifier is playing and sound very well,always looking for improvement, Best Regards and sorry for my bad english.

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