Hum free ABY humming

[R.G.]

1. Do ANY of the outputs share a copper-wire ground with the input jack?
2. How is this thing powered?
3. Unshielded transformers and coils can pick up hum as well as isolate it. Have you tried moving this thing from place to place? Is is sitting anywhere near a live computer when you try it?
4. Do you know what power line hum versus rectified power hum versus some other frequency? Can you recognize the difference between power hum and other low frequency oscillations?

[dist]

1. Non of the outputs share Any ground with the input. tried it with no results.

2. it is powered by a 18vdc adapter, Have also tried an 15vdc adapter but no change in sound. but I'm in the process of building a version with 9v and max1044. I'm also considering using 2 batteries

3. It sounds the same on several direrent amps, with straight guitar, buffered, loop from an DL4 and mp3 player. No mather were in the house i am.

4 Nope

Did i mention that i have built an 9v+max1044 version with no hum earlier. that was with 2 outputs, this one has 3.



Man i really love how helpfull and undersanding you guys are.

[R.G.]

1. Non of the outputs share Any ground with the input. tried it with no results.

Let's try it again, just to be sure. Connect the input ground to the output ground of ONE AND ONLY ONE output. Plug that output into an amp. Still hum on that output?

If yes, temporarily remove the transformer from that one output, and connect the opamp directly to the output which shared the input ground. Still hum?

2. it is powered by a 18vdc adapter, Have also tried an 15vdc adapter but no change in sound. but I'm in the process of building a version with 9v and max1044. I'm also considering using 2 batteries

Try the two batteries first. Still hum?

2
3. It sounds the same on several direrent amps, with straight guitar, buffered, loop from an DL4 and mp3 player. No mather were in the house i am.

Does it sound the same as you move away from the amp and turn it around? I'm looking for whether the transformers are picking up AC power line hum from the amp or other electrical equipment.

2
4 Nope

That's too bad. The really big bit of evidence you have put in your posts is that the frequency of the humming changed when you used a 10K to connect grounds. There is no way that the AC power line can change frequency from what you do to your pedal. That leads me to believe that the pedal is oscillating and by changing the ground connection you changed the frequency. If you could hear the difference, that would be a big step forward.

Look at this image: 


I'd like for you to (a) remove all except ONE transformer. (b) wire one of the outputs direct from opamp output to output jack, by using wires from the proper holes in the board where you removed a transformer. (c) In the ONE transformer, insert a 100R resistor and a 100uF capacitor as shown in the picture in this posting above. If the humming stops, then it was not "humming", it was the opamp having problems setting its output to the same DC level as its input with the transformer primary shorting the output to ground at DC.

2
Did i mention that i have built an 9v+max1044 version with no hum earlier. that was with 2 outputs, this one has 3.

No you didn't. That's unusual, and it indicates that there may be power problems as well.

You don't show how you wired your 18V and 15V adapters. Can you post that schematic?

[dist]

Don't know why, but this seamed to work for some reason.

Added a ground connect/break switch to one of the outputs and it went silent.

[dist]

Thanks for all the help BTW I would never have made it work without you, geofex, and ggg.

The buffers are stolen from the mini mixer on ggg, general idea from geofex and the connection of one of the outputt ground to input goring came from this site.