Zonk Machine - middle transistor is silicon ??? trim pot

Discussion regarding early stompbox technology: 1960-1975 Please keep discussion focused and contribute what info you have...

Re: Zonk Machine - middle transistor is silicon ??? trim pot

Postby Manfred » 24 Jun 2019, 09:15

Q2: B -.643V -.672V
C -7.16V -3.632V
E -0.1mV -0.1mV


I assume that the collector voltage was notet on the left and right stop of the "Bias" potentiometer,
which value was finally set?
Manfred
Diode Debunker
 
Posts: 857
Joined: 05 Apr 2009, 00:42
Has thanked: 1014 times
Have thanks: 606 times

Re: Zonk Machine - middle transistor is silicon ??? trim pot

Postby acidfuzz » 25 Jun 2019, 15:00

Manfred, No. The internal trimmer was adjusted to ~152K. Voltages were then measured with the external "FUZZ" control set at 1/2 (12 Noon) and at full clockwise rotation at room temperature (~70°F). Like in the Maestro Fuzz Tone and the MKI Tone Bender, the "FUZZ" control is essentially an external bias control for Q2.

For this message the author acidfuzz has received thanks:
Manfred (25 Jun 2019, 22:22)
acidfuzz
 
Posts: 25
Joined: 09 Sep 2010, 05:06
Location: Los Angeles, CA USA
Has thanked: 3 times
Have thanks: 16 times

Re: Zonk Machine - middle transistor is silicon ??? trim pot

Postby Manfred » 25 Jun 2019, 22:24

acidfuzz, thank you for your clarification.

For this message the author Manfred has received thanks:
acidfuzz (28 Jun 2019, 21:40)
Manfred
Diode Debunker
 
Posts: 857
Joined: 05 Apr 2009, 00:42
Has thanked: 1014 times
Have thanks: 606 times

Re: Zonk Machine - middle transistor is silicon ??? trim pot

Postby EmmG » 26 Jun 2019, 05:41

Cool stuff, acidfuzz. I just built a clone drawn by a friend who's been following this thread and posted to his new layout blog.
https://dirtboxlayouts.blogspot.com/2019/06/hornby-skewes-zonk-machine-mk-i-sige.html

Here's a hissy audio clip verifying it, even though I don't have the "right" parts yet.
https://soundcloud.com/user-562468024/alexs-zonk-hybrid-01
Russian germs and a BC558 will do for now. I look forward to hearing what works for other builders.

For this message the author EmmG has received thanks:
acidfuzz (28 Jun 2019, 21:40)
EmmG
Breadboard Brother
 
Posts: 54
Joined: 11 Nov 2012, 03:03
Has thanked: 16 times
Have thanks: 33 times

Re: Zonk Machine - middle transistor is silicon ??? trim pot

Postby acidfuzz » 28 Jun 2019, 21:55

Nice! Cool to see clones coming to life. If it helps, the 2N4061 hFE was 110, obviously with zero leakage (Si). You could easily use a Ge tranny in there, but the Si does make it more temperature stable. Here's the corrected schematic with the 2.2M output resistor:

ImageZonk Hybrid Schematic Correct by Jonathan Curl, on Flickr
acidfuzz
 
Posts: 25
Joined: 09 Sep 2010, 05:06
Location: Los Angeles, CA USA
Has thanked: 3 times
Have thanks: 16 times

Re: Zonk Machine - middle transistor is silicon ??? trim pot

Postby EmmG » 29 Jun 2019, 22:01

Yes, putting a lower gain one in Q2 got rid of all the hiss. I also tried a germ. and it sounded fantastic.
How different, if at all, did this sound and feel for you compared to the all germanium models?
EmmG
Breadboard Brother
 
Posts: 54
Joined: 11 Nov 2012, 03:03
Has thanked: 16 times
Have thanks: 33 times

Re: Zonk Machine - middle transistor is silicon ??? trim pot

Postby Electric Warrior » 30 Jun 2019, 12:07

acidfuzz wrote:There's a fun article on the Zonk here: https://www.vintageguitar.com/23068/hor ... -machines/

"Skewes translated that cultural shift into a business; with his wife, Madge, he founded his own musical-instrument company in ’65, from his home in Garforth, in West Yorkshire – far from swinging London. Among his first products was a fuzz pedal." I think it's cute that JHS started out just his wife and him working from home. Reminds me of the Acid Fuzz thing.

"To design and build his stompboxes, Skewes commissioned a small firm called Wilsic Electronics, in the village of the same name near Doncaster. Owner Charlie Ramskirr set to work."

“Charlie designed the pedals, and I guess he cribbed circuit ideas from others, though I do not know whether from the Tone Bender,” Skewes remembers.


I'm gonna take a wild guess and assume that whoever was building the Zonks got fed up with tuning the all germanium transistor set and the hybrids were an in between stage before the Zonk II? I pulled the pots, but no date codes. If there are photos of others with pots dating to 1968, I assume these were the final version of the Zonk before they moved on to the Zonk II?


Isn't the "D8" on the fuzz pot a date code? I've seen several with this code, but many germanium ones have it as well.
The hybrid version being the last of the Zonk Is makes sense and sounds perfectly logical, but it's only an assumption. I don't think we can say for sure.

According to the article and catalog pages picutured, the Zonk Machine and Zonk II were being sold concurrently at first, with the Zonk II being a much cheaper pedal. I guess at one point they simply discontinued the Zonk Machine? From what I understand they made the Zonk II well into the 70's. I've seen some with 1972 date codes on the electrolytics and pots.
User avatar
Electric Warrior
Diode Debunker
 
Posts: 724
Joined: 23 Feb 2009, 04:37
Has thanked: 20 times
Have thanks: 86 times

Re: Zonk Machine - middle transistor is silicon ??? trim pot

Postby nightraven » 30 Jun 2019, 13:54

Electric Warrior wrote:According to the article and catalog pages picutured, the Zonk Machine and Zonk II were being sold concurrently at first, with the Zonk II being a much cheaper pedal. I guess at one point they simply discontinued the Zonk Machine? From what I understand they made the Zonk II well into the 70's. I've seen some with 1972 date codes on the electrolytics and pots.

The earliest silicon Zonk II's look pretty similar in parts selection and construction to the vero Zonk I's. It is possible (but never certain!) that Wilsic(?) stopped making the I and started their version of the Zonk II in its place, and that the Zonk II in the product catalogue, advertised alongside the Zonk I etc was the Sola Sound version instead.
nightraven
TGP Refugee
 
Posts: 128
Joined: 21 Jul 2009, 19:38
Location: UK
Has thanked: 14 times
Have thanks: 61 times

Previous

Return to Vintage Stompbox Corner ( ... - 1975)

Who is online

Users browsing this forum: No registered users and 3 guests