Arkaim/Megalith transistor voltages & circuit adjusting

[JohnnyCreepy]

Maybe this fits here better than in General questions section. So I have a question for those who have built Arkaim and measured it with DMM. Most of the older threads about this circuit circulate around hefes, but those have saddly no use for my request.

Circuit is tweaked FF with boost. I’m wondering how sfock Arkaim Q1/2 values compare to regular NPN FF values. I’ve read great deal about FF topology, but my skill level isn’t experienced enough for figuring out where to aim with transistor bias adjustment with this particular circuit in topic.

So the questions:

• What have Q1-3 CBE voltages been on your built?
• Have high readings caused some problems?
• Did you adjust voltages changing emitter resistor values?
• Have you had wrong type buzzy note output from softer picking?

Issue what revealed to me today was that softer picking and lowering guitar vokume pot towards “the edge of breakup” led to nasty note with zapping buzzy tone without sustain. This problem didn’t occur me with my bedroom amp and I’ve ruled Q3 boost section out ftom it.

I did differ from suggested build applying low gain&leak germistors for the usual (silicone) blondistors for Q1&2 and a darling(ton) for Q3. Voltages on Q1&2 are okayish, but Q2c is 7.4V or more. I simulated my circuit values in Jack Orman’s Fuzz Face calculator and it revelead transistor currents are 1/10th of typical NPN-Si-FF. With some value play I figured out that reducing Q2e resistor from 10k to 3.6k ohm woukd bring collector voltage down to ~5V and currenfs up, but I’m wondering if there’s insight here about Arkaim circuit and transistor bias before desoldering Q2e resistors

 

[JohnnyCreepy]

I did some circuit tweaking. Changed Q2e 10Kohm resistor to 10k trimmer pot and Q2c voltages dropped instantly to 3.8Vdc. Slight adjustment and I was in typical FF measurements with collector voltage set to 4.7Vdc. Gave it a test with my bedroom amp and sputteriness had disappeared, but also some character.



Now switching mote heavy toggle on, it appears to sound more useable than before and suprisingly bassy with the darlington transistor @ 26k hefe. Guess boost section now works as meant.

Might be wise to reduce 0.68uF coupling cap before Q3 to remove extra bass as I’m mostly playing baritone in drop F#. 0.68uF was nearest value I had in hand building this circuit and it’s just too much. Also I should try adjusting Q2c from 4.7Vdc to 5-6Vdc and see how it translates to the fuzzy qualities.