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Tube DIY Asylum Do It Yourself (DIY) paradise for tube and SET project builders. |
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Tube DIY Asylum Do It Yourself (DIY) paradise for tube and SET project builders. |
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In Reply to: 12AX7 tube phono pre-amp HISS! posted by elwood625 on March 5, 2007 at 16:40:31:
What I would check:1. Is the first stage (MC pre pre) disconnected in the MM mode?
2. Regime of the input tubes. Lower plate voltage and current produce less noise. In a typical phono section, the input 12AX7 is run at less than 100 V and 0.1 mA.
3. Noisy tubes.
4. Grid resistor of the second stage more than 47 K, or noisy resistor at this position.
5. Too high heater voltageThere are other things, but these will make most inpact.
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- Impossible to view the schematics. - sser2 17:53:25 03/05/07 (0)
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