alexidoia

Instrument input Vs Mic input
« on: March 22, 2006, 04:51:06 PM »
Hi,
This is the original input stage of a mic preamp (Ampex 351) (click to make the picture bigger):


I modified it following this simpler one (only the black writings):


Now, beside the mic in,  I want to have an instrument input such as a guitar. The red writings is what I think I should do for this. But I would like your opinion on a few of things:
1) do I need to cut the circuit after C1 and R8 or can I just let them in the path ?
2) if no, even though the input transformer would not be of any use, do I need to connect 8 and 4 pins together as in the original schematics ?
3) is that 82k a good value ?

Thanks for your input and sorry about my lack of knowledge.
Alex


moamps

Re: Instrument input Vs Mic input
« Reply #1 on: March 23, 2006, 03:39:08 AM »
Quote from: "alexidoia"
.....1) do I need to cut the circuit after C1 and R8....


Yes.
Look at Gyraf's G9 input circuitry.

Regards,
Milan


 

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