Disconnected grid but still getting signal

[jeff]

 I built an amp with doug's preamp.http://www.el34world.com/projects/images/stereopreampschematic.gif Here's the problem I disconnected the cap from the 470K resistors and I'm still getting sound. It's not as loud as when it's connected but it's there.

Basically the 2^nd tube goes to the cap and the 3^rd tube has the 470K's on the grid but the cap is not connected to the 470K's

I've tried moving wires around and even different grounding schemes. I thought maybe as the first two tubes draw current it goes through the first dropping resistor too and maybe putting an AC on the 2nd tube's plate voltage so I connected them both to the power supply instead of having them in series.

How could the tube be getting the sound? Power supply? Cathode?

[jeff]

By the way I used all sheilded wire and at one point I had a pot instead of the 470K's. When I turned the pot very low I noticed that the amp got quieter, then silent , then a little louder. This to me seems like there is some phase cancelation going on when the input signal from the pot is the same level as this mystery inupt.

[PRR]

Did you follow Doug's grounding plan exactly?

[jeff]

 No I'm not sure what his plan is. I was going off this http://www.el34world.com/projects/images/stereopreampschematic.gif But looking back I saw this http://www.el34world.com/projects/images/stereoprelayout.gif Does this mean to daisy chain all cathodes and ground at one point? What do you do with the signal grounds? Ground to back of pot or daisy chain them and ground at same point.
 Oh I can see it now.

I used trees and the input ground and cath of each section is soldered to the ground lug then that is bolted to a point on the chassis with the filter cap. I read that this way since the cath and grid are connected at the same point if there is a loop the grid to cathode voltage should stay the same. I'll rewire it...again.

Is ground the most likely way this is getting signal? are there others(power supply?)