oops, this does look like a nest of some kind, and whatever critters are running around in those corridors will make some noise.
May I ask, why did you go from a pcb presumably designed by decware to your own design of point to point wiring?
Point to point wiring is like an artform just like designing a good pcb layout.
Structure and tidiness is a good guide of a good point to point layout.
If I may suggest;
to start with make 3 ground points. Call them star grounds if you must.
Ground 0 ; connect all power supply related earths including safety ground.
Make a T-off with a one inch 16awg cable to
Ground 1 ; connect all ground cables related to output tubes / trafos.
Make a T-off with a one inch 18 awg cable to
Ground 2 ; connect all ground cables related to input tube.
Grab all 4 earth cables related to input tube, twist well together and connect to ground 2.
Do the same for each ground cable surrounding output tubes and connect to ground 1.
For the rest of it, keep signal and power wires separated.
Volume control; if you have a position of 70k to 30k you would have 70k input impedance and 31k to input tube .
Please read your replies from WhiteDragon
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Thank you, rebone. I appreciate you taking the time to explain that to me. I owe kudos on two parts. First, I will take your advice and clean up that grounding scheme. Second, thanks for pointing me back to WhiteDragon’s post. It turns out the 100k resistor was the problem. I switched it out to a 10k resistor and the motorboating problem is fixed.
To answer your question, the reason I switched out the Decware PCB to my foul nest of wiring was because (1) the PCB didn’t have enough room for the big Miflex capacitors and (2) I’ve never built a point to point project before so just to entertain my hobby and curiosity for learning. So despite being a mess, I did accomplish both goals. I learned a lot and see that there is much more learning to be had - a good thing.
Also, I should say the PCB is a nice beginner board but has several problems on its own. By the time you solve the hum issues on the PCB you’ve almost point to point wired it anyway.
I’ll also say despite the criticisms I see all over on this circuit it sounds better than any other amps I’ve owned (nest and all) and have had many over the last 50 years, more expensive class A and AB, point to point and PCBs.
Anyway, again, thanks for taking the time to help.
To answer your question, the reason I switched out the Decware PCB to my foul nest of wiring was because (1) the PCB didn’t have enough room for the big Miflex capacitors and (2) I’ve never built a point to point project before so just to entertain my hobby and curiosity for learning. So despite being a mess, I did accomplish both goals. I learned a lot and see that there is much more learning to be had - a good thing.
Also, I should say the PCB is a nice beginner board but has several problems on its own. By the time you solve the hum issues on the PCB you’ve almost point to point wired it anyway.
I’ll also say despite the criticisms I see all over on this circuit it sounds better than any other amps I’ve owned (nest and all) and have had many over the last 50 years, more expensive class A and AB, point to point and PCBs.
Anyway, again, thanks for taking the time to help.