This one was quite tricky to trace. Got the topology figured out quite quickly but but identifying some of the capacitor values was quite difficult with these Greenies with faded markings. Had to look at several units, all had some minor variations but I think the layout below is pretty much spot on.
It is a heavy fuzzy overdrive with the gain control rolled back, maxed out it is a high gain fuzz. Most units had a 100k gain control with quite a limited range. It was later reworked for V4, using a 500kC potentiometer which gives a much more useful range.
It can be quite noisy with the gain maxed out (probably bcause of the layout itself, not the circuit design...) but short wires and shielded by an enclosure helps.
Oh dear me, this does look good
ReplyDeleteCan you post the schematic?
ReplyDeleteSorry, I will not upload schematics for the Blackhawk stuff.
DeleteCmiiw. Need more cut, M4.
ReplyDeleteValkyrie original use dpdt on-off-on. Right?
err, my bad. No need more cut. Im sorry.
Deleteon the way perf'ed this.
100u on pin 1 to 8 in 386?
Thanks Anders & Blackhawk! (again)
Most older Valkyries had DPDT on/on switch for the caps and that is what we traced. It is possible that some units had a on/off/on switch. The current V4 version has a on/off/on cap selctor switch indeed.
DeleteOh and for the 100uF cap across pin 1 and 8 for the LM386. I identified 100uF in one unit but some other units had smaller caps that I couldn't figure out the value for. I guess values down to 10uF will work well.
DeleteIt is important to remember that the builder, Brooks kept tweaking the circuit during the production to tune it in and improve it more to his liking I guess.
So some of the values is not set in stone like a tubescreamer for example
Built this and socketed some components and spent yesterday tweaking. In the end I ditched the tone and the clip sw. Sounds brutal and the low mid presence is just phenomenal! Thanks for the layout!
ReplyDeleteWhich capacitor value belongs at C13?
ReplyDeleteThe real value is still unknown but it is the in pF range. Probably larger than the 150pF due to the larger size. I went with a 500pF silver mica.
DeleteNote that some unit didn't had C13 populated so you don't have to use it.
What LM386 would be best? I have N1, N3, N4. Did someone try a 100k log for gain? Don‘t have the 500kc at the moment.
ReplyDelete