Tube Phono Preamps

[rayma]

I am also one of a small cadre of people who like regulated B+ for tube circuits.

Yes, that can make a big improvement in the bass.

 

[Eli Duttman]

If ever there was a situation that called for regulated B+, it's a phono preamp. That goes double for cascodes and their wretched PSRR factor.

 

[Bigun]

I have a project that will have a 500V B+ supply available so dropping some volts on a regulator would be no hardship. I was thinking that an active regulator will require a bit more intelligence on my part which adds to the interest. There does seem to be extra brownie points for using a shunt regulator vs series - thoughts ?

Don't forget that Mr. Blencow showed us how to use the top tube grid to get around 30dB of PSRR from a Cascode. It's not enough by itself but a better place to begin.

 

[stocktrader200]

this could easily run off one of those 1.6 VA pcb torroids run back to back off a larger 10VA 12v AC supply for the heaters.

 

[kodabmx]

Funny, my RIAA stage (modified Aikido) likes 335V @ 26ma. This implies 20VA before rectification.

 

[stocktrader200]

I was referring to the preamp on post#3 using a single 12AX7.
250v @ 4ma max. 1.6VA provides enough for each channel.

smaller transformers especially torroids leave a small magnetic footprint