Bottlehead Forum

General Category => Technical topics => Topic started by: vetmed on December 17, 2013, 02:03:58 PM

Title: MC cartridge "Step-up" and tube phono preamp
Post by: vetmed on December 17, 2013, 02:03:58 PM

Typically this  is done using either a transformer or some sort of solid state device. Is there is any reason that a tube couldn't do the job? Or is the signal from a typical low output MC cartridge so close to the noise floor that using a tube is not practical?

Robert Lees

Title: Re: MC cartridge "Step-up" and tube phono preamp
Post by: Doc B. on December 17, 2013, 02:18:39 PM

We just spent a few months attempting such a feat. We sought very low noise tubes, did a lot of testing of various resistors to see if they contributed to noise, ran a few different high voltage shunt regulator options, paralleled tubes to reduce the 1/F noise, and tried a whole bunch of other stuff. The end result used 4 6C45pis per channel. It sounded amazing, but we just couldn't get an acceptable noise floor.

Title: Re: MC cartridge "Step-up" and tube phono preamp
Post by: vetmed on December 17, 2013, 06:11:05 PM

Well based upon my reading on the net on this subject I can't say I am surprised. Did you try any triode connected pentodes e.g. E180F, E280F, D3a? Good used E180F are cheap as are D3a, E280F are a little pricier :) Plus Russian 6J9P are dirt cheap equivalents of E180F.

Robert Lees

Title: Re: MC cartridge "Step-up" and tube phono preamp
Post by: Doc B. on December 17, 2013, 07:54:28 PM

We tried the 7788. Just about as quiet, but didn't sound as good.