Regarding the Gary Hurst Tone Bender MK1 Signature Model

[fuzzymuff]

Comparing with the original circuit of the Tone Bender MK1 with the Gary Hurst signature Tone Bender MK1, the Gary Hurst model has added resistors around the attack control(2k2, 33k) and the output (56k).  Also, there is an additional 25uf electro cap near the output as well.  What was the purpose for these changes?

The orginal Tone Bender:



The Gary Hurst Signature Tone Bender MK1 model.

[LucifersTrip]

25uf lets more base frequency thru. The 47K at the end of the GH version basically gives you a 50K vol pot. Look at the FZ 1 and 1A:
http://experimentalistsanonymous.com/diy/Schematics/Fuzz%20and%20Fuzzy%20Noisemakers/Maestro%20FZ-1%20and%20FZ-1a.GIF

The 2.2K + (33K // 50k = 20K) let's you go from 2.2K to 22K on the base of Q2 instead of 1.8K to 51.8K

as I detailed in the other thread, the larger that value, the lower Q2C voltage....so you won't be able to drop the Q2C voltage as much. Since most of the sweep of the "fuzz" (really the bias) happens in the 1st 50% of the 50K of the SS version, the GH version with 20K works really well.   Of course, this all depends on whether you use a 180K or 470K from Q2B to -9V

[fuzzymuff]

Thanks LuciferTrips.  So basically Gary Hurst just made these changes to make the MK1 easier to bias and a little more bass response.  I was looking at the zonk machine schematic, it looks like a variant of the MK1.  I'm going to breadboard both the Gary Hurst model and the Zonk Machine to compare.

[slacker]

That 2M2/47k divider can't be right can it? That gives an absolute max output of about 200mV (9*47/2200) probably less, is the original stupidly loud?

[LucifersTrip]

the orig can hit unity at 50% or less...the 2.2M is the savior...remove that and you're in hell, though many decrease it to increase volume/gain

[LucifersTrip]

I'm going to breadboard both the Gary Hurst model and the Zonk Machine to compare.

the biggest difference is that the Zonk has a much smaller input cap so it's a decent amount more trebly.

[fuzzymuff]

I'm going to breadboard both the Gary Hurst model and the Zonk Machine to compare.

the biggest difference is that the Zonk has a much smaller input cap so it's a decent amount more trebly.

Hmmm...more trebly than the original MK1?  Now, I want to breadboard it and hear it.  Do you know if AC125 transistor would work with the Zonk or is it essential to use OC44 and OC75s?

[fuzzymuff]

That 2M2/47k divider can't be right can it? That gives an absolute max output of about 200mV (9*47/2200) probably less, is the original stupidly loud?

The one I built, has unity at noon.