Posted by Tnuctipun [ 64.12.116.14 ] on February 11, 2005 at 16:27:33:

In Reply to: Re: RIAA preamp? posted by Damir on February 11, 2005 at 15:24:08:

I am going to try for a two-stage valve pre for MC. Cascode of the front end stage. Probably a pair of triode strapped, high gm pentodes. Get the first stage gain in neighborhood of 200:1 and feed the RIAA filter and end with a CCS-loaded 6BQ7 perhaps. Getting half or a third of mu-squared from a cascode is not too difficult I think.

the troubles I can see from here are mainly the high output z of the cascode stage and the correspondingly high z RIAA EQ. The Guinevere-style plate load will do a good job of driving cables.

I may decide to put in a variable capacitance in the front, as the cascode will be nearly free of Miller effects.

Still looking at it.
regards,
Douglas

That and noise....heh-heh-heh!

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