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    Building, troubleshooting and testing of these amplifiers should only be
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    the safety precautions around high voltages.

NP-100v12 Build

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I recently build a hybrid headphone amp from NP-100v12: DIY 12AU7 (ECC82) Tube / IRF510 MOSFET Headphone Amplifier .

Currently, I am combating a hissing noise that increase in volume as I turn the pot. I have built a LM317 regulator for it. I also have used an SMPS, but still have noise. The difference is, using the linear PSU the noise is a hissing noise which increase in volume as I turn my pot, while using the SMPS the noise is a constant humming noise.

The tubes in it is a 12AT7, which based on the original thread is compatible for this amp. What could be the problem in my build? Your help is appreciated

Also, can I use this amp as a preamp/buffer? If so, do I need to change something? Thanks!
 

PRR

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Joined 2003
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> hissing noise that increase in volume as I turn the pot

Then it may be coming from *before* the pot.

Or through thin air, if it is not in a metal box.

A 12AU7 would have less of these noises than a 12AT7.

Or through the power supply wires since there is NO power filtering shown on the amplifier plan.
 
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