Matt911 wrote:
Hi there
I am looking to use this amp as a preamp in my hifi system, this will go before my power amp of course. Will I still need the MOSTFET and lM317 as a for the current gain and constant current source if they are not directly driving the headphones?
Anything else I should look out for when using in a hifi system?
Thanks in advance! Great circuit cant wait to build! Thank you so much for all the time and effort put in!
As a pre amp, you do not need the mosfet and lm317.
You directly connect a hifi cap at where r3 4k7 joins 12au7, at the output of the cap, you put a 100k to ground instead of the 1k.
You measure output voltage dc to be zero at your pre amp before you connect to power amp.
Hi I am also keen to try this as a pre amp. Can anyone suggest a good value output capacitor to go with the modified circuit utilising a 100k please? Some values mentioned in a previous thread but I was not clear it was concerned with changing to a pre amp.
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