Breadboarding didn't go as planned

[Ripthorn]

Hi guys, working on my submini tube amp and the breadboarding session this evening didn't go as well as I wanted. This is my first go with tubes, so I was doing a simple design that uses only one dual triode (6111). I put it together, but didn't get anything out.

I audio probed and found that I am getting nothing off the plate in the first stage. I am feeding in 17.76V to the plates, and I have 12.6Vac (according to my transformer, 14.46Vac according to my DMM) and I have it connected like this. One end of the ac in to heater pin of first tube (pin 3) from heater pin of first tube (pin 6) to the heater of second tube (pin 3) and from pin 6 of second tube to the other end of the ac. I used the second tube only to drop the voltage since my transformer is 12.6V.

This is my first project with tubes, and the tubes are NOS, so I assume they are good, so I am wondering if you guys have any suggestions. One thing that seems strange to me is that the voltage seems to be 14.4V on each tube, even though I think I wired them in series. I hope I didn't damage anything. Thanks for any ideas in advance.

[Ripthorn]

So a little update. I now have all the power working out, so that the tubes give a nice orange glow. I am getting about 11V at the plates (with no plate resistor, about 7 with). At the grid I get my input signal, no problem, but at the plate, I only get a really loud hum. With the plate resistor I can faintly hear a really distorted sound embedded in the hum, but with no plate resistor I hear only hum.

So that you have some background, I have the signal coming in through a 68k to grid. Off the cathode I have a .68u cap and a 10k resistor. I tried taking the output from the plate both straight and through a 22nF cap. I get the same result each way.

Does anyone have any idea what is going on here? I did notice that I am getting a bit of a voltage drop at the heater when I test (drops to about 5.4V, though my LM317T gives me 6.3V without load). I am really all out of ideas, because everything tells me that it should work, but it doesn't. I have tried it with two tubes and the different sections of each. Help!

[DonP]

I think you need to post a schematic of what you are trying to do.

Also, the reason for the voltage drop on your heaters is that your power supply can't supply the current to maintain the 6.3 volts.

Good luck and keep studying!

[Ripthorn]

Thanks for the response. I got the power supply issue fixed, but I have a new problem. A schematic for reference is below (some values are slightly different). My new problem is that the first stage works great, I send it through the caps and resistors to the grid of the next stage, but I get nothing on the plate, even if I pull out the resistor/capacitor series coupling the grid and plate. I am not intimately familiar with the inner workings of these tubes, but I don't have any crossing leads or shorts that I can see. Any ideas?

[img:800:582]http://i652.photobucket.com/albums/uu24 ... in6021.jpg[/img]

[Ripthorn]

Not sure what I did, but I got it going. The clean section sounds really good, I am still working on the distorted section and then tweaking is going to take me a good while.