Into the mix

Greetings on day one with new kit built EW. In order to practice in the "Cone of Silence" (headphones) I am sending the output signal from the Theremin through a tiny Behringer mixer, and that seems to be working fine. I am attempting to mix in another signal from my computer so that I can play along with Band-in-a-Box accompaniments. As soon as I plug another signal into the mixer, the theremin signal drops to almost nothing. I unplugged the EW and tried input from a different source in the same channel. I was able to hear that along with Band-in-a-Box just fine. I'm mixed up. . .Would you believe mixed off? Any thoughts would be appreciated.

Hi and welcome to Thereminworld.

From what you describe, here is the picture that I get in my head:

Computer and
Etherwave ---> Behringer Mixer --> Headphones

A few things to try:

1) Instead of the computer, try plugging something else into your mixer. Does the Etherwave volume soften now?

2) Does the pitch of the Etherwave change along with the volume?

3) Are you overdriving your mixer's output buss?

That is, are the overload lights "on"? If so, a loud computer signal would make the theremin signal sound soft in comparison.

4) Are your input trimmers set properly?

Your computer produces a line level signal. Are you feeding the computer's signal to a line level input? Same with the theremin.

With the information you have provided, you may want to check your level (volume) adjustments to be sure you have the desired balance between the computer signal and the theremin.

[i]-- Kevin[/i]

Hi Kevin,
Thanks for the suggestions. I tried plugging in my turntable in lieu (or is that loo) of the computer. Both the turntable and theremin were as clear as a bell. When I plug the computer in the theremin sounds scratchy and hummy as well as being very weak. As soon as I disconnect the computer the theremin sounds fine without changing any settings. It seems like there is some kind of interference from the computer?
TSL

In another test with the computer turned off, but still connected to the mixer (tape in input), the theremin still didn't sound right. As soon as I disconnect the cable from the computer (but still connected to the mixer), the theremin sounds fine. I wonder if the proximity to all the wires associated with the computer, printer, scanner could be the problem? My nerve center is in a rather small space.
TSL

Try a different cable between the computer and the mixer to assure that the cable isn't the problem.

Does your computer sound ok through headphones connected directly to the computer?

Thanks again Kevin for your interest in my dilemma. I tried different cable with same result. Both are high quality cables, and work fine in other applications. Sound from computer is good through mixer with each cable as well as with phones plugged directly into computer. I tried jacks on front and back of computer with same result. The computer and the Theremin/mixer are plugged into two different wall outlets. Could a problem with the house wiring (i.e. bad ground) be the culprit? I'll try different outlets!
TSL

What model mixer are you using? Also are you running your computer into the tape in/RCA in? I use a set up close to yours, and it works fine. Let me know the model, and I may be able to help a little!

Mi Matts,
The mixer is a Behringer Eurorack UB502, and I am running the computer to the tape in (RCA plugs). A friend of mine knowledgeable in electronics has suggested that the problem may be ground loop. He suggested placing some type of isolation transformer between the computer and the mixer. ???????
TSL