pt

[longji98]

I am considering this 12ax7 preamp. what kind of the PT should I use? many thanks for help.

 

[longji98]

no help?.
Secondary: 125-0-125 V, 100 mA
Filament winding: 6.3 V, 2 A
.... will this one be ok for it?

 

[aardvarkash10]

sounds more than sufficient...

that should give you plenty of voltage and certainly current capability for an a_7 preamp in any configuration! Bolt the sucker in there!

 

[Tom Bavis]

You're running 0.5 mA in the first stage, 1.5 mA in the second. Another 2 mA for a second channel... plus 6.3V at 0.6A or 12.6 @ 0.3A.

 

[azazello]

Cathod potential of second triod must be approx. 123 v!

 

[longji98]

Re: sounds more than sufficient...

that should give you plenty of voltage and certainly current capability for an a_7 preamp in any configuration! Bolt the sucker in there!

You're running 0.5 mA in the first stage, 1.5 mA in the second. Another 2 mA for a second channel... plus 6.3V at 0.6A or 12.6 @ 0.3A.

Many thanks for reply..
so. .., Can I also use this PT for M7 if late update? I am a beginner about it, please kindly give me a suggestion. thanks

 

[leadbelly]

Time out here, we can't spec a PT until you tell us the rest of your PS design. Are you planning to use a full wave tube rectifier, or a bridge? What filtering? To get a good low ripple 300VDC out of a 125-0-125 transformer, you will need to use a bridge.

 

[longji98]

Time out here, we can't spec a PT until you tell us the rest of your PS design. Are you planning to use a full wave tube rectifier, or a bridge? What filtering? To get a good low ripple 300VDC out of a 125-0-125 transformer, you will need to use a bridge.

Thanks Brother, yes. I am planning to use a bridge because of there is not a Filament winding at 5V(CT).. ..

so. if I use full wave tube rectifier, what kind of the spec. PT should I have.....
Thanks.

 

[leadbelly]

Thanks Brother, yes. I am planning to use a bridge because of there is not a Filament winding at 5V(CT).. ..

so. if I use full wave tube rectifier, what kind of the spec. PT should I have.....
Thanks.

Look, I'll ask my question again, what in detail are you planning to build for a PS? How can we tell what transformer to buy if you won't say what rectifier and what filtering you are going to use? An small tube rectifier and a CRC filter will burn a lot of volts. A big tube rectifier and a CLC filter won't.

 

[longji98]

Look, I'll ask my question again, what in detail are you planning to build for a PS? How can we tell what transformer to buy if you won't say what rectifier and what filtering you are going to use? An small tube rectifier and a CRC filter will burn a lot of volts. A big tube rectifier and a CLC filter won't.

Thanks Brother
Bridge: IN4007x4(I have some) . prefer CLC.
Tube rectifier: full wave 5u4g. CLC.

 

[leadbelly]

Here's a start. You can use this to refine what you want:

http://duncanamps.com/psud2/index.html

 

[longji98]

Here's a start. You can use this to refine what you want:

http://duncanamps.com/psud2/index.html

Thanks brother . I get it.

 

[longji98]

You're running 0.5 mA in the first stage, 1.5 mA in the second. Another 2 mA for a second channel... plus 6.3V at 0.6A or 12.6 @ 0.3A.

This preamp is not burning too much ma. .. I think the PT just with 40ma current capability is enough for it, right, ,,,,
I dont k know how to calculate the ma in the second stage... how do you get the 1.5ma? thanks for help