buzz w/ nothing plugged into inputs. Goes away once jacked in.

[wicked1]

I've always had amps that buzz with nothing plugged into the input, but all of them I have built myself have been dead silent, cable in the input or not.

I built the aikido pre-amp, and I get a LOUD buzz w/ nothing on the input. I plug in some cables, and the buzz stops.
What causes this? It's not good! Im afraid if anyone ever unplugs the cables w/out shutting it off first, my speakers could explode! (well not explode, but it is VERY loud!)


Question 2.. I get a high pitched buzz when I use my PC as an audio source plugged into the pre-amp. I use my PC w/ several amps and have never had this issue.. Maybe that's just the gain on the pre, picking up pc noise? I'm not too worried about this one, as cd players, mp3 playrs, etc are all fine.

And last question, since I'm posting.....
The power in my house goes down when the microwave goes on, or a dehumidifer, etc. This aikido stops working for the second the power droops. All of my other amps keep on going through it. Any ideas on this one? I've got plenty of capacitance on the PS.. About 200uf, which is the same as a couple of other amps Ive built. (10uf - L(10h,100r) - 100uf - 1kR - 100uf)

thanks for any info..

[Glowbug]

I assume you've star grounded everything?

[wicked1]

Im using John's all in one PCB, which has on board power supply. But, I'm not using the on board (haven't stuffed any of the components). I've just got a few p2p components. 6ax5-C-L-C-[PCB] (the final r-c is on the PCB).
The PCB is laid out w/ star grounding, and the center of that is where I have the ground from the tx and CLC connected..
So I guess short answer, yes.

I'm more concerned w/ it cutting out when my home AC droops. I'm doing the laundry, and it's horrible! every time the motor or pump turns on or off the music cuts out, and it's often! I've never seen anything like it!

I just tried measuring b+ and heater w/ multimeters while causing the AC to droop (turned on microwave), and didn't see any change, tho the sound did cut out. I'm sure there was a change, but it was too fast to show up on my meter.