Hi,
I have build this mic preamp with semi parametric eq and it is more cutting than boosting. Cut is around 10db but boost only around 3db. Why?
I have build this mic preamp with semi parametric eq and it is more cutting than boosting. Cut is around 10db but boost only around 3db. Why?
Probably because you are using log pots for the controls. Use linear pots and it will likely do what you want. In other words, the 'flat' position may not be in the middle.
Well, I must say that I love the connection between pin 2 +3 on the first (left-most) IC (not numbered). Than, I do not know what U1A + B are supposed to do. Please explain.
The tone controls seem to be OK. I would take each section of the circuit and run it through LTSpice individually and see what they do. E
The tone controls seem to be OK. I would take each section of the circuit and run it through LTSpice individually and see what they do. E
Thanks bob and mickey
The short between pin 2 and 3 is only on the schematic. Not on PCB.
I think that bob could be right. I think I have put a log pot in place of R20 but must be Lin pot.
I have already spiced the whole schematic and it worked fine so it must be a pot problem.
I will go back tomorrow to my workshop and check it.
Thanks
The short between pin 2 and 3 is only on the schematic. Not on PCB.
I think that bob could be right. I think I have put a log pot in place of R20 but must be Lin pot.
I have already spiced the whole schematic and it worked fine so it must be a pot problem.
I will go back tomorrow to my workshop and check it.
Thanks
bob is right, when you use the wrong type of pot at the centre pos it will not give you the same result. But bob is wrong, at the end position you should have the same boost/cut as the other pot. So, maybe, there is a wiring or parts problem somewheere. E
Yep true mickey.
I did some more spice and did find out that if I turn down the input volume R5 the asymetrical behavior is even more pronounced and if I turn full up R5 it is much more symetrical.
I did ad a buffer between R5 and the tone control and it looks to work perfectly. I try this tomorow on the board.
I did some more spice and did find out that if I turn down the input volume R5 the asymetrical behavior is even more pronounced and if I turn full up R5 it is much more symetrical.
I did ad a buffer between R5 and the tone control and it looks to work perfectly. I try this tomorow on the board.
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