Linear L50 Valve amp - biasing issue

[cjhudlin]

Originally Posted by Edward Huggins

In Post#28 the OP asks if there is a Phono preamp with multiple inputs. i don't know of any as they are dedicated to a single MM or MC cartridge. You can buy them from £15-00 upwards. Rega or Project are recmmended as they will have a far lower noise floor than any part of the L50.

Thanks for the reply Edward

[bikerhifinut]

Originally Posted by Edward Huggins

In Post#28 the OP asks if there is a Phono preamp with multiple inputs. i don't know of any as they are dedicated to a single MM or MC cartridge. You can buy them from £15-00 upwards. Rega or Project are recommended as they will have a far lower noise floor than any part of the L50.

By multiple inputs I assume the OP means line level inputs in conjunction with a Magnetic cartridge input?
If so what you need to use these amps is a preamplifier. There are many choices here, I'd counsel a reasonably modern solid state one rather than a potentially flaky Valve vintage one. Also the Cartridge input will be significantly better on a modern SS pre. There shouldnt be any compatibility issues either.
manufacturers like Rotel NAD etc etc made some pretty good preamplifiers in the day and I have seen them on the web and in dealers for reasonable prices (used).
Something like a Rotel usually have useful Tone controls too so you can bypass those on your mono amps too good purpose.
For the record, my fallback and personal reference preamp is a Rega Cursa which I use with ALL my valve power amps. The earlier Mk1 can sometimes be found for not too much money. No tone controls but usefully the Rega preamps have adjustable gain levels making them flexible and suitable for anything from a sensitive Leak power amp right up to amps like QuadII (and some others) which need 1.4V to drive to full output.
I do fiddle about with valve preamps and disc stages but hand on heart i have to say the silicon based rega pre is about as good as it gets. I use a rega offboard moving coil disc stage and its really very very good. The moving magnet ones from rega are also excellent value if you need an offboard one (the board comes as standard on the preamplifiers).
Other makes are available and most if not all will give very acceptable results, way in excess of the performance capability of your Linears.

A.