Hello! Long time follower, first time builder here. My goal is to build a JM Sig and modify it a little to include SSS step filters and Rock/Jazz switch. I also want to to look exactly like SSS #004
Fast forward from October of last year to yesterday, my build is coming along really well and ready to share the progress so far. I do have to build the cabinets and modify the circuit to include the SSS step filters and rock/jazz switch, but here's my BOM:
*Note - I do not receive any discount or kickbacks from the vendors. My wallet reminds me I paid full price for services This is also a personal project and not lining up to compete against members here.
Chassis
Designed by me using AutoDesk Inventor and AutoCAD (Thank you Taylor @ AN for critical dimensions)
100W 4x 6L6GC Layout designed to accompany 6x 9 pins (one for cathode follower if necessary)
You said Nik from Ceriatone told you to swap the blue/brown leads, that's the first thing I'd think too, but that noise doesn't quite hit the 'screech' I've heard when phase was wrong, but did you try that?
or the other suggestions? It didn't seem like you qualified if you had or not, just what they were?
I think otherwise it seems as you get up to a specific bias point it starts humming that there's an oscillation happening due to amplification hitting a certain point? Not sure otherwise, try getting the hum and adjusting lead dress too, especially of the output wires.
pompeiisneaks wrote: ↑Thu Feb 22, 2018 5:17 pm
You said Nik from Ceriatone told you to swap the blue/brown leads, that's the first thing I'd think too, but that noise doesn't quite hit the 'screech' I've heard when phase was wrong, but did you try that?
or the other suggestions? It didn't seem like you qualified if you had or not, just what they were?
~Phil
Thank you for your kind compliments! I have not tried swapping the OT wires around yet. I'm gearing up to do a round of troubleshooting tonight and tomorrow morning so I'm hoping to run through a list of things to check. I'd ideally like to swap the OT wires around last since I've dressed everything nice and tight on that part. Doh! But I'm still open to trying it for sure. I'll check the PI portion first as well. The troubleshooting I've done since firing her up for the first time yesterday:
Traced reverb tube section. Seems ok compared to the layout
Checked the reverb tank in/out connections (I did have the RCA's reversed initially which made the reverb extremely low volume but that's been corrected)
Removed the mid boost runs from the preamp circuit to see if maybe the long cable run affected things.. no difference made there
Another thing I'm going to try is cutting my zip ties to move the the "contour" and bias connections away from the OT runs to the output jacks.. Willing to try it all! lol
If you don't want to swap the ot leads on the power tubes, you can swap the output leads from the PI coupling caps instead. Does the same thing. If you've got more leeway there. It's a pretty common problem that's super easy to fix.
caps8419 wrote: ↑Thu Feb 22, 2018 5:52 pm
chassis looks great! Why did you mask the preamps tubes on the outside of the chassis though? oops moment?
That was intentional My theory was the preamp tubes mount from the bottom so the grounding will span the whole tube shield vs the two screws on the top. It likely won't make a difference but that is one of the things I over-thought about lol
Last edited by rccolgan on Thu Feb 22, 2018 7:11 pm, edited 1 time in total.
pompeiisneaks wrote: ↑Thu Feb 22, 2018 5:55 pm
If you don't want to swap the ot leads on the power tubes, you can swap the output leads from the PI coupling caps instead. Does the same thing. If you've got more leeway there. It's a pretty common problem that's super easy to fix.
~Phil
Ah!! I like that That just bumped up the list of things to try first now!
pompeiisneaks wrote: ↑Thu Feb 22, 2018 5:55 pm
If you don't want to swap the ot leads on the power tubes, you can swap the output leads from the PI coupling caps instead. Does the same thing. If you've got more leeway there. It's a pretty common problem that's super easy to fix.
~Phil
Ah!! I like that That just bumped up the list of things to try first now!
Yeah I learned it here from someone else, not recalling who, but as usual this place rocks for this kind of info