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otto88 5th June 2009 10:28 AM

300B driving 845

The 300B is $$$, but its very linear, there are many options (vs eg the 45) and supply is pretty assured. So looking at the 300B driving 845 SE

I believe the 300b can be relatively sensitive to its driver, or in this case input
stage. Was considering 10Y, 26, 46, 71A, 76. Need to check sutrabvality.

(I recall there was a circuit(s) for a 300B driving 845 SE).

Any comments?


rknize 5th June 2009 03:11 PM

The original AudioNote Ankoru, if I remember right, was 7044 -> 300B -> dual 845.

ianc13 5th June 2009 04:10 PM

The Ankoru was 300B driving 845 and the circuit was published in Sound Practices Issue #12. There is a PDF of the article on the internet if you search - you could loose an 845 per channel and run with a 10K OPT instead of 5K.

In the next issue was the Nuance 845 which is 6072A -> 300B -> 845SE. The original article text. schematic and parts list can be found at the author's website:




ErikdeBest 5th June 2009 04:36 PM

DHTrob uses the 300B to drive the GM70, using an interstage. The schematics are published at the GM70 yahoogroup!

otto88 7th June 2009 07:47 AM

It might be the Nuance I remembered, thank you.
Unlike the Nuance, this project isn't quite "cost-no-object", though hopefully it will be the amp for my next few decades!

I found 2 versions of the Ankoru. The Japanese with parallel single-ended 211s and UK, yes 7044 > 300B > PSE 845

The UK Ankoru's designer Andy Grove said
"Various input configurations were tried, all using the E182CC/ 7044 valve for its powerful sound. The original and best sounding configuration gave the amp so much gain as to be impractical. . . The 7044 was always run at a high current to really bring out its flavour".

Not sure, I guess by "powerful sound" he means not distorting at higher levels??

I see DHTrob drives the 300B with the 71A

(Though the 71A and 26 are very susceptible to electrostatic coupling from surrounding metal objects, there are ways of dealing with this

Back to the question:
Apart from electrically being up to the task of being the front end for the 300Bs,
my question is about the ol' subject of SE tone . . Some tubes and circuits bring out the SE "magic", others are "clean" . .

Would the 6072A be considered clean?
Of those I mentioned - the 10Y, 26, 46, 71A, 76 - what is their tonal signature?

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