Building the Muffsy Phono Preamp PP-2

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Comments

[Harold Barrel]

Hi skrodahl, great project! :-)

I'd like to ask you one thing: how is important the capacitance tolerance of the capacitors used in this preamp? I refer especially to the polyester capacitors - which are responsible for the equalization if I'm not wrong. Should I choose M (20%), K (10%) or J (5%)? Thanks in advance!

[skrodahl]

The 47 and 68 nF capacitors form the RIAA filter. I'd choose 5% or better. The other capacitors can be 20%, with no ill effects.

[Harold Barrel]

Many thanks for your response :-)

[joaocandre]

Going to try this as sson as possible. One question though - is it possible to set an adjustable gain through a potentiometer knob?

[skrodahl]

It could be done, but I don't recommend it.

The high amplification of the (very low) signal from your turntable, means that any small variations between the two potentiometers will become quite noticeable. This is especially true if you use a stereo potentiometer.

Since this is DIY, you can adapt the gain to suit your needs:

https://hackaday.io/project/4788-muffsy-phono-preamp-pp-2/log/15926-more-gain-less-gain

[joaocandre]

Thank you for your reply... Indeed that was what I suspected, however I saw that you used switches to vary the gain and it got me wondering. Maybe if I find a way to limit the pot's range to the same values you set with the switches (just wondering, probably going to try the PCB as is first)

[dmilesson]

Snyggt jobbat Håvard :) Göran låvorda den, men själv har jag lämnat vinylspelare bakom mig.

[skrodahl]

Jag hörde du var mer inne på lasrar och sånt numera. :)

[tomatoskins]

This kit looks really fun to work with!