Thanks Robert. Good eye on the resistor! Actually, there is a 1 ohm 2watt resistor under there. I had some 2watters already and thought I'd give them a try... Now that you mention it, I used those for separate biascheck resistors in another amp I modded. I hope it doesn't blow.Looks great Jake. I'm not sure what you have off the bias point to ground. Should be a 1ohm 5 watt resistor (I used a 1%).
Well, here I just followed what the 2rock guys did in my el84 ruby amp. The wire from the impeadance switch goes to the hot lug of both jacks. The ground wire from the output transformer goes to the ground lug of the nearest jack. The farthest jack gets it's ground through the chassis. I used star washers on the jacks to make sure the ground was solid. In this way, you can use either jack alone or both jacks together.Also, I don't know if it is incorrect or not. I wired my two speaker outputs the same as you did. My jacks are the shorting kind, so I think it doesn't work correctly,not sure though, when I use only the farthest jack from the impedance selector. It just seems unusual to only have one wire going to that furthest jack.
It's a little bit of a story... When I got my el84 ruby, it had the 2rock OD caps in it, with values similar to the A1a schematic, except for around the loop bypass circuitry. The series caps around the bypass switch create a smaller value than there should be according to the A1a schematic. So, I was going to change that anyway (impoved bass response, BTW). Some one recommended that I use M150s in the amp, so I swapped them all out while I had the amp open. I noticed the tone was a little bit smeared with all 150s, so I decided to just use OD polypros in the tone stack, figuring that the M150s would smooth things out at the middle and end of the signal chain. So, I ended up with a clearer tone, that was still smooth. Since it worked in that amp, I just started with that configuration in the El34 build.I'm curious why you mixed the different caps in the preamp section. I am also not satisfied with the tone controls. I wired them according to our layout diagram but they really don't alter the tone that much. Fortunately to my ear the amp doesn't need much tweaking of the tone controls.
Also, if you have the time, try .02 values (I didn't have them, but stacked two .01 values) in the tone stack and at the output tubes-- it removes low midrange mud, without killing bass.
As for tweaking the tone controls. Here's an idea. Use a DPDT cent off switch for the bright switch. On one pole you could use your 180pF value. On the side and other pole you could do a couple different things. You could add series capacitance to the treble cap, making the total value 50pF, for less gain, and for a fendery response. Or you could wire a 330K resistor across the treble pot, for a marshally response from the tonestack... Or you could try Steve Ahola's discovery of dropping the input resistance on the first gain stage to very low values (e.g., 33k), which is supposed to smooth out the treble response. (I have not tried this yet).
Thanks for your comments. I think I might have to replace that 1ohm resistor...
Jake