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]

(I have a 130-0-130 ptx )

Thanks.

With this PT you can also get 300V B+

 

[Eli Duttman]

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]

Re: Re: phonostage with 150VDC B+

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.