Croft pre amp valve question

[Audio Al]

HI
Before I start tube rolling am I correct in thinking after looking at " The Gubbins inside " that the tube on the left is the phono stage and the centre and right are the left and right channels :scratch:

Fanks in advance :D
17385
17386
17387

[Firebottle]

Not quite Al.
The left and centre are phono, it takes two valve sections for the phono circuitry per channel. :)

[Audio Al]

it takes two valve sections for the phono circuitry per channel

:scratch: does that mean it should have 4 valves :scratch: , Alan whats the other valve do then ?

[struth]

Half a valve half a valve onwards :)

[Firebottle]

:lol:
Each valve has two sections, as in TWIN triode Al.

The right hand valve is the output valve, one half for left channel, one half for the right channel.

[Audio Al]

Doh ! :doh: my head hurts when it comes to understanding internal gubbins :)

[worrasf]

Al - the valves I sent you to trial are all ECC83 or variants - several are matched pairs so swap 2 at a time in the left and centre positions. Handle the glass as little as possible (use a hanky or glove) to keep sweaty oils off the tubes. The right hand valve in your photo is the line stage (single valve for both channels) also likely to be an ECC83 in your preamp (my 25RS uses a 12BH7)
Steve


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[worrasf]

Looking at your photos the 2 valves in the phono stage look like frame grids (?Teslas) but can't be sure - if they are "true" Teslas they are nice tubes


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