phonostage with 150VDC B+

[alexg]

Am looking for a tube phonostage with 150V B+. Can somebody give me schematic or point me to one?

(I have a 130-0-130 ptx )

Thanks.

[Eli Duttman]

GE, who 1st developed mag. carts., devised a circuit around the 6SC7. I've attached a schematic of a Fisher unit that followed GE's lead.

A number of changes are necessary to use modern mag. carts. The I/P resistor has to be 47 KOhms and the HF roll off is achieved by placing a cap. across the O/P.

I'm working with a fellow who has a pair of the Fisher mono units. Perhaps he will be willing to provide a scan of the regulated PSU that was devised, with help from the "crowd" here.

BTW, that cicuitry will work with a 'SL7 or a 5751. Don't forget a DC heater supply.

[arnoldc]

Hi Eli, that looks nice and simple. Does your friend like the sound?

[revintage]

Originally posted by alexg

(I have a 130-0-130 ptx )

Thanks.

With this PT you can also get 300V B+

[Eli Duttman]

Originally posted by arnoldc
Hi Eli, that looks nice and simple. Does your friend like the sound?

Arnold,

The project is not complete. So, no comments are available. FWIW, Avery Fisher's ears were quite decent.

A couple of threads regarding the matter can be found on AA. Search against the Tube and Tube DIY forums.



Edit: fixed typo

[alexg]

Originally posted by revintage


With this PT you can also get 300V B+

How do I do that? Voltage doubler?

Thanks.

[revintage]

Just neglect the CT and use a bridge-rectifier. If you want to use a tube rectifier you can make the bridge from the tube together with two silicon diodes.

[arnoldc]

i.e. graetz bridge

[revintage]

Yep

[alexg]

Thanks for the input.

I think I can adopt my ptx for Thorsten designed circuit (12ax7/6dj8) phonostage.

BTW, how do you compute for the voltages using the hybrid rectifier (two diodes and a tube rectifier). do multiply the voltages from the diodes with 1.41 and use that to simulate using PSUD2?

Thanks.