-=> Roy J. Tellason said to Greg Mayman
 -=> about "BAG OF CHIPS" on 01-29-04  04:05.....

 GM> They were unity gain, remember.

 RJT> I don't think that's likely to be a problem.

It would be if it was a magnetic pickup. The output of those
usually needs quite a bit of gain.

 RJT> It's a ceramic pickup,  basically the same idea.  The only thing I
 RJT> need to put in there is something to give me the proper equalization...

Usually no equalization was used. I don't know whether the
pickups contained some inbuilt correction for the "wiggle" in the
RIAA curve, but I rather suspect it was ignored.

If you want, you can use the following network either between the
pickup and the preamp or between the preamp and the following
stage.

in ------+---- C1 ------+------- out
.        |              |
.         ---- R1 ------+----- R2 ---- gnd

Typical values:

(a) between p/u and preamp: R1 = 510k, R2 = 2.2M, C1 = 150 pF
    R2 is chosen to give a suitable load to the pickup.

(b) following preamp: R1 = 2200, R2 = 10k, C1 = .033uF
    R2 may be a 10k volume control.

Values have been rounded to nearest readily available values.
Values may be scaled as long as the time constants are preserved;
C1R1 = 75uS, C1R2 = 318uS

 RJT> I have plenty of small caps and ferrite beads and such stuff around to
 RJT> deal with those issues,  and no particular strong sources of radio
 RJT> nearby,  so I'm not terribly worried about it.

The only other factor is the possible noise in the amplifiers.

   ,-./\
  /     \ From Greg Mayman, in beautiful Adelaide, South Australia
  \_,-*_/    "Queen City of The South"    34:55 S  138:36 E
       v

... What is research but a blind date with knowledge. - Will Henry
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