Hello! I need a phono preamp circuit on nuvistors - I want to make such a device for myself . Can anyone suggest such a scheme? Perhaps - someone has already made such a preamp and got a good result. I will be very grateful for the information .
Glass Audio published one such phono preamp by Eric Barbour in issue 4/1993. Lots of information on the subject
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the magazine is defunct since many years now but the article may be copyrighted.
I do have the magazine and would be glad to help and scan the article but I'm not sure if it is legal. Maybe someone who knows better can advise?
I do have the magazine and would be glad to help and scan the article but I'm not sure if it is legal. Maybe someone who knows better can advise?
Nuvistors tend to be microphonic. They work well at RF, where that's not an issue. In audio, not so much.
In the USSR in the 60s - nuvistors were used in some models of tape recorders - amplified the signal from the head...... The microphone effect is not a problem , it is eliminated by damping . Many glass tubes also have a microphone effect .
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There are plenty of Nuvistors with the same basic performance as common noval triodes, i.e. equivalents of the 12AX7 and 6DJ8. I think the Russian 6S51N / 6S52N parts are good places to start. So all you need to do is choose an existing design based on noval tubes and substitute a nuvistor - more or less it is that simple.
Not quite defunct. It was part of the Old Colony family of magazines, The Audio Amateur, Speaker Builder and Glass Audio. Ed Dell (RIP) , the Editor, got the folks at Circuit Cellar to take it under their wing and it is now published as part of AudioXpress.
Many of the article are freely available as PDF's.
Maybe someone will be interested in this publication. There are circuits with the use of nuvistors . The author of the schemes is Sergey Toropov . Корректоры от Сергея Торопова | УМЗЧ.РФ
Due to their tight grid construction I would expect Nuvistors being less microphonic then the standard 12AX7. But I am not a tube expert.
"Tight" tends to mean "higher pitch". Like when you turn up the tension on a guitar's strings. Or shorten them (ukulele).
Also the smaller electrode spacings mean both higher Gm and more output volts per micron of grid-shake.
None of the Nuvistors is a real-close match to any common glass tube. The very tiny electrodes encourage different design compromises, and in the direction of higher performance (for some intended market; TV tuners not the same as tape preamps).