I fired it up as it was and turned everything up- I got a very faint but clear signal from the guitar... sounded like the volume was just turned all the way down...
So, I started thinking on what I could have disturbed when I took it apart to fix my pot mistake... and it dawned on me that the VVR uses B+ to lower overall volume....
Got the DMM out and checked the continuity of B+ from the PS board to the main board.... many 100Ks.... so I hit the connection to the main board with fresh solder..... and YEAH.... it was a joint that was either cold or I jerked it loose manhandling the board....
I have the 100K in instead of the 47K..... I like it! It's not giving me the Express harmonic feedback, but the tone is very tasty.... Any ideas on if the Express feedback is possible with this little beyotch????
Ron Worley wrote:I have the 100K in instead of the 47K..... I like it! It's not giving me the Express harmonic feedback, but the tone is very tasty.... Any ideas on if the Express feedback is possible with this little beyotch????
Ron
Congrats on getting it going!! Just wondering what your bias is and what B+ voltage you have on your power tubes. You might be able to tweek the bias a little bit ti get the feedback your looking for. You can also play with the value of the NFB resistor too. I used a 33k but you can go larger and get less nfb which would also translate to more gain. More things to play with. What speaker cab are you using? Open or closed back? What do you think of the bass response?
I have 164V B+, which is a little low, but close to the 170V you said with the 500K VVR pot. Were there any other changes based on going from 1M to 500K? I have it biased at -32V per your suggestion... but maybe I should jack that up some?
I will play with the NFB as you suggested, I'd really like to get some "Sing' out of her....
I am using my ~1975 Marshall MKII combo's 2x12 greenbacks, and it's an open back... so bass response probably isn't as tight as a 4x12 closed back... But I did not play it very long as it was 9 at night and I'm building in my detached garage.... don't want to be too bad of a neighbor....
I will report on my findings when I get a change to play with it tomorrow night...
Any chance that enclosing the rest of the chassis would help with the hum??? After all, it is "spawn of Express"....
I put a 100k in mine the other day and as Dana said, there is a bit more sustain and it gets dirty sooner. Tonewise, its a little browner at this point also. Still cleans up reasonably well too.
I have no real preference at this point towards the 47k or the 100k.
With the VVR it can get a bit muddy as you turn it down below 12 'o' clock but I can compensate with the tonestack. I noted that with the 47k and the 100k. Seems a bit wierd having a VVR on it but it is suprisingly loud when you krank it. That said, I think the VVR works pretty well.
bobobo wrote:He's working on the instruction..... Dana please speed up.. I'm waiting
Guys, I'm going as fast as I can. The first 30 pages of the manual are complete. I just need to finish the section on installing the boards in the chassis and how to test the amp before fire-up. I am going to work hard today to try and get it finished. I think I have spent more time on the manual than I did designing the amp. The kits are in stock and I will probably post them on our new web page for sale one day next week. I am also still tryig to get some better clips recorded. If everything goes right I am shooting for an April Fools day release
Last edited by UR12 on Sat Mar 28, 2009 3:41 pm, edited 1 time in total.
I am still working on them. I have them almost finished and have given them to another forum member to proof read for me. As soon as I get the last part done and any corrections made I should be good to go. It's taken me longer to write the instructions than I would have thought but they are very detailed with a bunch of pics. I will post here as soon as I get them finished.
Hi Dana! As a lazy guy like me, I have postponed my Lil Devil building until I get your instructions. As a matter of fact it is a perfect project to build in my summer cottage because of it`s small size. First you build some hours Lil Devil, then you go to sauna and after that a little barbeqe with some beer. Ain`t life wonderful????. Harry
The kits are in stock and I will probably post them on our new web page for sale one day next week. I am also still tryig to get some better clips recorded. If everything goes right I am shooting for an April Fools day release 
