Audio and Video Talk > Valves / Vacuum Tubes

Line Level Tube Preamp

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Mars:
Here is the circuit I am following (credit to Glassware Audio Design):



Some notes:

Supply voltage is 250V

20k value I get by parallel 22k and 220k

I am using two 6J5 in stead of a single 6SN7GT tube.

For the moment I am running the circuit without the cathode bypass capacitor on first triode.

Earth bar is floating inside chassis. I intend to do the double diode connection between IEC earth and chassis



Audio earth is supplied by RCA connection to the power amplifier or source. In my test setup the computer is earthed and the JVC power amp unearthed.

Moonraker:
"
I have the preamp between my sound card and a JVC A-K20 amplifier. The sound is deep and expansive. There is no comparison to the sound without the preamp."


What does that mean?  I suppose - it sounds better?

That must be the wonderful influence of frequency spectrum distortion, harmonic distortion,  intermodulation distortion, hum modulation, and microphonics (aided by having a bunch of components hanging on the tube pins).

And - there are not even transformers in the signal path.  Imagine - with those..  :flame: :flame:

Zilch:

--- Quote from: Moonraker on August 13, 2021, 08:55:06 AM ---The effect of the 1M resistor in parallel is zilch

--- End quote ---

Well... :giggle:

Moonraker:

--- Quote from: Zilch on November 26, 2021, 07:14:10 AM ---Well... :giggle:

--- End quote ---

 :)
I guess zilch is what you find inside vacuum tubes...

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