Sending signal from CMOS counters through looper and to my amp

[Bryce McVaney]

I have a MIDI keyboard hooked up to my Arduino, which puts out a clock signal which is fed into an HCF4024. The divided outputs go through 10k pots and then 10k resistors, and they are mixed. What I'd like to do is send the signal through a looper pedal (this pedal: https://www.donnerdeal.com/products/donner-looper-effects-pedals-unlimited-overdubs-10-minutes-of-looping) and then to my guitar amp. Here are the specs listed for the pedal:

Power Supply: DC 9V
Parameters: Input: 110v-240v, 50/60Hz, 0.2A
Output: 9V 500mA, 4.5W
Current draw: 128mA
Input：1/ 4" monaural jack (impedance：470k Ohms)
Output：1/ 4" monaural jack (impedance：100 Ohms)

What do I need to do to send the signal through the pedal without possibly damaging it or getting any distortion? Will the signal need to be attentuated, will I need some kind of buffer?

[Bryce McVaney]

Ok I tried just bringing the signal way down with a voltage divider and feeding it through the pedal and into the amp. This seems to work, except that the amp produces a loud buzzing sound which, unless the signal is really hot, is louder than the actual signal. According to my research, I have a ground loop. What do I need to do to eliminate this?

[antonis]

Brake to loop...!!!

Can't tell you more, about star-ground or so, without a schematic..

[Bryce McVaney]

I talked to some of my "real musician" friends and I guess I really didn't have a ground loop, I was just using the wrong cable. Problem solved.