Hi, I have successfully built a pretty great sounding Total Recall.
Everything works great except there is clock noise (high pitched whining) in the delays past about 3 o' clock on the delay time pot. This isn't a huge issue, except that I have spent so much time on this build, I want it to be ironed out.
I originally followed the calibration-by-ear instructions in the build document but when the clock noise issue surfaced, I attempted an oscilloscope calibration.
Not all of the readings measured the same as in this guide:
https://sites.google.com/a/davidmorrin.com/www/home/trouble/troubleeffects/electro-harmonix-memory-man/eh-7850/eh-7850-calibration (https://sites.google.com/a/davidmorrin.com/www/home/trouble/troubleeffects/electro-harmonix-memory-man/eh-7850/eh-7850-calibration)
Specifically I ran into problems when trying to reach unity gain between pins 14/15 and 7 on the NE570. With the trimmers in their max positions, I can still only get about half the gain on 14/15 as I get on 7.
I don't know if this issue is related to the clock noise issue, but I'd love to get input on these issues.
Things I've tried:
reduced C40 to 220pf (this didn't seem to change much)
replaced the compander (tried SA571, NE571, and NE570 with little to no difference)
Thanks in advance for your input!
play with the clock capacitor.
also check the value of the ?B100k delay time pot.
Which BBD are you using?