Change 12AY7 to 12AX7 Tube. Waht new settings?

[jpetek]

Hello,

I have a Question. My Preamp is original with 12AY7 Tubes. It is very difficult to find new 12AY7 Tube.

My idea is to change the settings from a 12AY7 to a 12AX7 Tube. I saw that on some pins are 22 Ohm resistors.

Has anybody a idea what value is the right for 12AX7 tubes?

Bye the way it works with 12AX7 too but I think with not the best performance.

Thanks for your help


Josef

 

[MrCurwen]

Just to make sure: you are talking about a HIFI preamp, not an instrument amp like the tweed era Fender guitar amps?

 

[rongon]

Hello,

I have a Question. My Preamp is original with 12AY7 Tubes. It is very difficult to find new 12AY7 Tube.

My idea is to change the settings from a 12AY7 to a 12AX7 Tube. I saw that on some pins are 22 Ohm resistors.

Has anybody a idea what value is the right for 12AX7 tubes?

Your question is so general and vague that it cannot possibly be answered with any accuracy.

Which pins are those 22 ohm resistors connected to?

What amplifier is this? (make and model)

Do you have a schematic of this circuit?

Bye the way it works with 12AX7 too but I think with not the best performance.

This may very well be the case. You could also put a 12AT7 (ECC81) in there, and that might also work but not with best performance. I'm not sure what that proves, though.

--

 

[jpetek]

it is a Phono Preamp from Hajdinjak Labs. No schematic.

I will check witch pins.

 

[rayma]

it is a Phono Preamp from Hajdinjak Labs. No schematic.

You'll have to reverse engineer this, by drawing out the schematic, to get any help.

 

[MrCurwen]

Phono circuits usually incorporate the plate resistance of the tubes in the RIAA correction curve. It is not possible to change the tube type without a complete redesign.

JJ and Electro Harmonix still produce this type with reasonable prices.

 

[petertub]

Hello,

I have a Question. My Preamp is original with 12AY7 Tubes. It is very difficult to find new 12AY7 Tube.

My idea is to change the settings from a 12AY7 to a 12AX7 Tube. I saw that on some pins are 22 Ohm resistors.

Has anybody a idea what value is the right for 12AX7 tubes?

Bye the way it works with 12AX7 too but I think with not the best performance.

Thanks for your help


Josef

12ay7 is made as new production from JJ slovakia. There should
not be any problems getting them in europe.
And No, there is no benefits in using a ecc83 in it's place, it can only be less
accurate ( we are talking about a riaa amp )

tubetown.de has 2 brands :
https://www.tube-town.net/ttstore/a...ht00pcj5riv398m49g02u2&keywords=12ay7&x=0&y=0