Quickie for Tape or Phono

xcortes · 13768

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Offline xcortes

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on: June 01, 2010, 06:33:57 AM
I'm thinking of experimenting with a pair of Quickies and make a couple of mono tape preamps.

My idea is to insert the eq circuit between the two sections of each amp. I will basically build the tape eq section of the Seduction for which I would (from memory as I don't have the schematics in front of me):

Replace the pot in the first section with a 250k trimpot.
Replace the pot in the second section with a 1M resistor.
Between the two stages I will install a a passive equalization network composed of a series resistor R1 of 66Kohms and a series-shunt network composed of a 1.5Kohms for NAB (1.07k for IEC) resistor and .033uF cap.
Use a 0.1 uF coupling capacitor.

The main problem I see is gain since the 6DJ8 has an amplification factor of 33 vs about 5 for the 3S4.

Any comments?

Xavier Cortes


Offline Doc B.

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Reply #1 on: June 01, 2010, 07:42:46 AM
The gain will be too low. PJ has suggested in the past that he might look at the feasibility of a battery powered tube phono preamp, but it is not a high priority at the moment.

Dan "Doc B." Schmalle
President For Life
Bottlehead Corp.