Playing through an amp is fun and good practice, but sometimes I want to play along with a jam track. With simple amps like my Pignose, there is no option for an auxiliary input such as a computer, MP3 player or smart phone.

After some searching around I was able to come up with a very simple design for a two channel mixer. One input is my guitar and the other is for an auxiliary device.

Shown are two schematics. The first utilizes two 10k pots to allow individual adjustment of the inputs. I built this circuit and it worked perfectly, but then it occurred to me that my guitar and auxiliary input devices had volume controls of their own, so pots on the mixer were (for me anyway) redundant. Thus the second schematic. This is a very simple circuit involving only four fixed resistors and three audio jacks.

Her is the prototype. Note, by mounting the three jacks on a common metal plate the they are all grounded to a common ground so no need for more wiring or soldering.

The layout is one 10k resistor from the positive post of the two input jacks to the negative post, thus the 10k to ground circuit. There is also a 10k resistor from the positive post of each input jack. These are soldered together and then wired to the positive post of the output jack. That's it. no more wires.

I tested this circuit using my semi-smart phone, Pignose and one of my guitars. There was no hum or buzz apparent. I first played a jam track and adjusted the volume (on the phone) so that it matched the guitar volume. I then used the volume knob on the Pignose to set my final volume.

It was a kick to finally be able to play to a jam track with only my basic Pignose amp. Opens up some nice options for Buskers needing a battery powered amp. It is also a nice addition for all those amps that we have built from bits and pieces.

Anyway, thought I would share this. I plan to mount this panel on the back side of my Pignose as a permanent addition.