Debugging help with MN3207 Application Circuit

[jukeboxhero01]

I've built the application circuit from the MN3207 datasheet on my breadboard. The MN3207 and MN3102 were purchased from Visual Sound.
I'm using 4558 opamps in place of the AN6550 opamps. I'm using a 50k trimmer resistor to "Adjust to minimize distortion" as on the schematic. I'm powering the circuit with +9V DC. Whenever the circuit is turned on, there is always a high pitched whine, regardless of the setting of the 50k trimmer resistor. I'm reading about  8.4 volts on 3207 pin 4 and 3102 pin 8, and about 4.6 volts on the rest of the pins.(excluding power and ground)

A similar problem was encountered in this thread:

http://www.diystompboxes.com/smfforum/index.php?topic=78981.0

The MN3207 data sheet:
http://www.experimentalistsanonymous.com/diy/Datasheets/MN3207.pdf

The MN3102 data sheet:
http://www.experimentalistsanonymous.com/diy/Datasheets/MN3102.pdf

[maarten]

Probably you are hearing whining from the clock (3102). Try replacing the 200K at pin 6 of the 3102 by a 500K pot, so you can regulate the clockspeed (thus delay time) and see if you can find a setting at which the whining disappears - this will give you a better value for a fixed resistor (if you want to put that in, in place of the 200K). Alternatively you mach change the 100p (either to 47P  or to 147 or 200 p (in this latter case by parallelling the 100p with another capacitor of 47 or 100 p).

If this does not help, you also could try to replace both the resistors at the output of the 3207 by a trimpot of 10K, so you can adjust this to get to a minimum level of disturbance - sometimes that will help.

Remember that this is kind of a basic circuit application; usually you will find different types of measures in a delaypedal to battle clock whining, such as more intensive filtering and also compressing/expanding.

Maarten