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Old 10th July 2012, 02:26 AM   #71
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Quote:
Originally Posted by rjm View Post
While coupling capacitors might be more audible than other individual components, most preamp designs have several for good reason: they are extremely useful.
Thanks a lot for the answer Richard
Do you mind elaborating a bit? The reason I thought of the above was simplicity.
I really do not need all those switches. Only a 2 way source selector and a volume pot, both of which I am thinking of implementing with LDRs, so no clicking or scratching from them.

Something like that

Click the image to open in full size.

When phono is on, R1 and R5 act as the attenuator, while R2 is ~30R.
At the same time R3 and R4 are ~50M while R6 is ~30R.

When CD is on, R4 and R6 act as the attenuator, while R3 is ~30R.
At the same timeR1 and R2 are ~50M while R5 is ~30R.

And on mute, all series resistors are ~50M, and Shunt ones ~30R.

Sorry for the longish post. I just really value your opinion
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Old 10th July 2012, 05:58 PM   #72
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Richard Murdey
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Electrically speaking, that will work. Do you propose to have a physical input switch, and if so where is it positioned on the circuit above?
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Old 10th July 2012, 07:27 PM   #73
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No switches in the signal, only the LDRs. The rotary switch will control only the current in the LED side of the LDRs
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Old 29th July 2012, 02:24 AM   #74
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ok after so much delay, I finally started buidling the preamp.

I will keep everything in a single box, so I am powering the b-boards from phonoclone.

Since I have not populated the z-reg parts, should I install the 100nF caps in C3 spot?
Board version is GZ 10e
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Old 29th July 2012, 02:49 PM   #75
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Yes, the 100 nF ceramics are needed independent of what is powering the circuit, they ensure the stability of the transistors Q1-4.
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