pt

longji98 · 30th October 2008, 06:32 PM

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

longji98 · 30th October 2008, 07:09 PM

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

aardvarkash10 · 30th October 2008, 07:18 PM

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 · 30th October 2008, 07:51 PM

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 · 30th October 2008, 08:50 PM

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

longji98 · 30th October 2008, 08:59 PM

Quote:

Originally posted by aardvarkash10
that should give you plenty of voltage and certainly current capability for an a_7 preamp in any configuration! Bolt the sucker in there!

Quote:

Originally posted by 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.

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 · 30th October 2008, 09:23 PM

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 · 30th October 2008, 09:55 PM

Quote:

Originally posted by 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.

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 · 30th October 2008, 10:27 PM

Quote:

Originally posted by longji98

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 · 30th October 2008, 10:50 PM

Quote:

Originally posted by leadbelly

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.

30th October 2008, 07:18 PM	#3
aardvarkash10 diyAudio Member Join Date: Mar 2007 Location: Auckland, NZ	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! __________________ Yes, conservatism thrives on low intelligence and poor information. But the liberals in politics... continue to back off, yielding to the supremacy of the stupid. It's turkeys all the way down. - George Monbiot, guardian.co.uk, 6 Feb 2012

30th October 2008, 09:23 PM	#7
leadbelly diyAudio Member Join Date: Dec 2002 Location: Calgary, Alberta	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. __________________ Aerodynamics are for people who can't build engines. Enzo Ferrari

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30th October 2008, 07:09 PM	#2
longji98 diyAudio Member Join Date: Mar 2008	no help?. Secondary: 125-0-125 V, 100 mA Filament winding: 6.3 V, 2 A .... will this one be ok for it?

30th October 2008, 07:51 PM	#4
Tom Bavis diyAudio Member Join Date: Jun 2002 Location: Macedon NY	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.

30th October 2008, 08:50 PM	#5
azazello diyAudio Member Join Date: Aug 2008 Location: Bulgaria	Cathod potential of second triod must be approx. 123 v!

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