Lots of RF at full gain - is this common?

[eframp]

Hi all,

Just finished assembling my J99 with the 990C's I got from Yavuz. I've got 'em set at 20V. It ran perfectly first thing out of the chute. Yay Tim!

So there's this one issue - not a show-stopper by any means - that I'm curious about: at the very highest gain setting, I'm getting a LOT of RF, but only at the highest setting, not even the next-highest. I notice the RF noise changes timbre (not level) if I have the lid on or not, and I notice it changes timbre (not level) also if I move my wiring harness.

I only have one other pre in this case (a C84) and it does not do this. The J99 is in the 6th slot away from the PS, and the C84 is in the 8th.

Thoughts?

e

[tpryan]

Clearly, if you can hear it, it's not RF. Do you mean hissing? Are the inputs terminated, or are you just cranking up the gain with nothing attached?

[eframp]

Clearly, if you can hear it, it's not RF. Do you mean hissing? Are the inputs terminated, or are you just cranking up the gain with nothing attached?

Good point about the RF. Guess I meant RFI?

It isn't hissing, it's a rizz.

Listen to this. At the top, the knob is at 10, then about 1/3 of the way through I switch to 11, then about halfway through you can hear me switch it to 12 and tap the wiring harness a bit.

http://www.ericframpton.com/Clients/J99_noise_demo.wav

Sounds the same with or without a mic (condenser or dynamic, tried both) attached, using a known good mic cable.

[tpryan]

Is the chassis close to other devices with big power transformers? Does it make a difference if you move the unit around? Do you have fluorescent lights or dimmers in the room? Does the sound change when you touch the controls? Are you sure the crimp connections are good, and the connectors are properly installed in the housing?