Fuzz with variable voltage
- Thread starter jhaneyzz
- Start date
BuddytheReow
Moderator
Like, a SAG or BIAS control?
Feral Feline
Well-known member
You can always add your own starve circuit of choice to just about any fuzz (save digital).
What's in the Hephaestus?
What's in the Hephaestus?
chris.knudson
Well-known member
Or you can starve the voltage at the source -- some power supplies will let you do this, or you can build one of these...
Robert
Reverse Engineer
Fuzz Foundry is the first one that comes to mind.
Ginsly
Well-known member
I JUST asked this exact question, and you can read the responses here: https://forum.pedalpcb.com/threads/...o-executive-a-la-hephaestus.19788/post-245441
I haven’t built the Executive (Bosstone) yet, but some fine folks here gave me great pointers. I’m very green still, so not sure if what they recommended is a Transistor Bias situation or overall Voltage Starve. I’m not sure which one the original Hephaestus has either! They might have similar effects on the Bosstone… Maybe?
I haven’t built the Executive (Bosstone) yet, but some fine folks here gave me great pointers. I’m very green still, so not sure if what they recommended is a Transistor Bias situation or overall Voltage Starve. I’m not sure which one the original Hephaestus has either! They might have similar effects on the Bosstone… Maybe?
CR0SSBL4DE
Active member
Just an idea I had reading the thread. You may even add a resistor for higher source impedance / SAG. Not sure, I'm not a fuzz guy.
I've never seen this used in a pedal, so maybe there's a better way of getting the same result.
I've never seen this used in a pedal, so maybe there's a better way of getting the same result.
jhaneyzz
Well-known member
But that means I already have several pedals that do that and I won't have to make any new pedals. What a buzz kill.... or should I say fuzz kill...
Robert
Reverse Engineer
Well now just HANG ON. Let's not start talking crazy.....
Ginsly
Well-known member
I guess the question is- does the Hephaestus just have a straight-up transistor bias knob or an overall starve? If it’s the former (which sounds likely), I’m not sure how the Mythos is getting quite that much lower octave. I certainly get it on a Fuzzly Bear clone, but it‘s not quite as strong… Maybe the Mythos has a transistor bias knob with a different pot value than would normally be used for that..? If not, I don’t see how the Hephaestus is any different than the other “Bosstones With Bias” in that regard. Here’s the pic I posted in the other thread:
Ginsly
Well-known member
What does that entail? I have an Executive Fuzz to build and wanted to add the Heph’s volts control. It sounds like the advice in my original thread may be a transistor bias mod. I’m still new at this, please excuse my lack of knowledge. Would love some guidance!
Robert
Reverse Engineer
Yep, looks like a series resistance similar to the Stability control on the 'Foundry feeding the entire circuit through R5. The combination of R5 and the pot are probably the equivalent of R5 on the Executive Fuzz schematic.
The next resistor over is the LED CLR, then a filter cap.
Robert
Reverse Engineer
Omit R5 from the Executive Fuzz PCB.
Connect a wire from the top pad of R5 to lug 3 of your new Starve pot.
Connect a 10K resistor from lug 2 of the Starve pot to the lower pad of R5 on the PCB.
It just dawned on me that this is exactly what we're describing right here, so take a look at this schematic:
The Ermahgerd uses a 1K resistor and 100K pot.
Here's a bigger / higher res version of the pic above.
Robert
Reverse Engineer
To answer your question directly, this is almost exactly that, except it also includes a Volume and Gain pot, and an EQ switch.
If you really want a 1-Knobber jump the gain and volume pots and omit the EQ switch.
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Robert
Reverse Engineer
It doesn't have the EQ switch and the Starve values are different so it's probably just a clone, not a clone of a clone.
This is also the basis for some (most?) of the Trombetta fuzzes as well. If I'm not mistaken Paul Trombetta designed the WTF for Rockett.
Ginsly
Well-known member
Ah! Ok, this is very interesting. In the original thread they mentioned using a 1k resistor to connect the lower pad of R5 to lug 2 of the new pot (B50K was mentioned by a very helpful @PedalBuilder ), then connecting lug 3 directly to the emitter leg of Q2, and connecting (the unused) lug 1 to lug 2. Nothing connects to the top of R5.
Beginner’s question: are both methods achieving the same thing?
Do I still connect lugs 1 and 2 in your method?
Funny enough, I was THIS close to getting an Ermahgerd! In my last PedalPCB order. Doh! Guess I’ll have to mangle this Executive instead!
Also - @Robert you mentioned that the Starve values are different between the WTF and the Hephaestus - how can you tell? The pic doesn't show the pot value for the Mythos. Curious, as I'm gonna try this mod on the Executive very soon - thanks!!
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Ginsly
Well-known member
Can I ask you to explain how I would set up a transistor bias knob on the Executive? I added an overall voltage starve following Robert's very helpful instructions, and it actually sounds excellent.
I think I'd ALSO like to be able to adjust the transistor bias, as it might help me dial out some of the circuit hiss. I think having both of those controls could be interesting, too. Thanks @Big Monk!
