Rockman Ultimatum Distortion Generator Pedal [Traced]

General documentation, gut shot, schematic links, ongoing circuit tracing, deep thoughts ... all about boutique stompboxes.
Post Reply
User avatar
Cybercow
Information
Posts: 22
Joined: 21 Feb 2017, 02:20
Has thanked: 10 times
Been thanked: 28 times

Post by Cybercow »

Considering only about 50 of the Rockman Ultimatum Distortion Generator pedals were ever released, and having gotten my hands on one for a time, I thought it wise to trace and verify the circuit. I spent a good amount of time, coincidentally with Robert (@PedalPCB) doing a trace of the same pedal at the same time, I took the time to breadboard the circuit based on the trace I made - but without the "low-battery" and "buffered-bypass" sections.

http://endprod.com/filez/Ultimatum_Prot ... one_01.jpg

The complete set of notes, layouts and schematic is here: http://endprod.com/filez/Ultimatum_Trac ... matics.pdf

Robert (@pedalPCB) completed his trace and has already produced his version as a PCB project (Proposition Distortion) of this rare pedal here: https://www.pedalpcb.com/product/pcb504/

Enjoy!

User avatar
JTEX
Information
Posts: 23
Joined: 27 May 2021, 13:31
Has thanked: 7 times
Been thanked: 60 times

Post by JTEX »

Thanks!
I fail to understand how the output volume pot works the way it's drawn. It would have very little influence on the output volume at any setting. Are you sure the outpot jack doesn't come off the bottom of the volume pot? (pin 1). Then it would make sense.

User avatar
Cybercow
Information
Posts: 22
Joined: 21 Feb 2017, 02:20
Has thanked: 10 times
Been thanked: 28 times

Post by Cybercow »

JTEX wrote: 27 Sep 2022, 19:48 Thanks!
I fail to understand how the output volume pot works the way it's drawn. It would have very little influence on the output volume at any setting. Are you sure the outpot jack doesn't come off the bottom of the volume pot? (pin 1). Then it would make sense.
It works perfectly. It may not be drawn "conventionally", but it works just fine. Note the lug numbering in relation to the pot rotation. It's the same as if the pot (in the schematic) were vertically flipped and the lug numbers swapped. I'm confident that you can visualize it.

User avatar
FiveseveN
Cap Cooler
Information
Posts: 591
Joined: 25 Oct 2009, 21:20
Location: Romania
Has thanked: 215 times
Been thanked: 116 times
Contact:

Post by FiveseveN »

Cybercow wrote: 29 Sep 2022, 12:48 It's the same as if
No, it's not. How would it form a voltage divider if two pins are shorted (2 and 3 in this case)?
Ignorance more frequently begets confidence than does knowledge. (Charles Darwin)

User avatar
Cybercow
Information
Posts: 22
Joined: 21 Feb 2017, 02:20
Has thanked: 10 times
Been thanked: 28 times

Post by Cybercow »

FiveseveN wrote: 30 Sep 2022, 05:50
Cybercow wrote: 29 Sep 2022, 12:48 It's the same as if
No, it's not. How would it form a voltage divider if two pins are shorted (2 and 3 in this case)?
Well, it works as it is and same as when so wired on the breadboard. What else can I say?

Sure, the connection from lugs #1 & #2 can separated and the output taken directly from lug #2 instead of the joined #1 & #2 lugs. But to say this doesn't or can't work is just silly.

User avatar
phatt
Transistor Tuner
Information
Posts: 1224
Joined: 04 Aug 2010, 05:17
Location: Morayfield SE Qld AU
Has thanked: 8 times
Been thanked: 343 times

Post by phatt »

I see it drawn as a Variable Resistor and as such it would effect the output volume, at least down to the value of R22
If If pin 1 was grounded (bypassing R22) then at zero the output would be nil, a dead short across the signal path = no sound.
I've seen this Variable Resistor idea used as Volume control in a few amp circuits, not common but it does work. [smilie=a_whyme.gif]
Phil.

User avatar
Cybercow
Information
Posts: 22
Joined: 21 Feb 2017, 02:20
Has thanked: 10 times
Been thanked: 28 times

Post by Cybercow »

phatt wrote: 01 Oct 2022, 00:25 I see it drawn as a Variable Resistor and as such it would effect the output volume, at least down to the value of R22
If If pin 1 was grounded (bypassing R22) then at zero the output would be nil, a dead short across the signal path = no sound.
I've seen this Variable Resistor idea used as Volume control in a few amp circuits, not common but it does work. [smilie=a_whyme.gif]
Phil.
Phil - precisely. The 8K2 value of R2 simply prevents the signal from ever going directly to ground. So there will always be some signal going out.

User avatar
soulsonic
Old Solderhand
Information
Posts: 3880
Joined: 27 Jun 2007, 03:38
my favorite amplifier: Traynor YVM-1
Completed builds: too many!
Location: Morgantown, WV
Has thanked: 183 times
Been thanked: 468 times
Contact:

Post by soulsonic »

FiveseveN wrote: 30 Sep 2022, 05:50
Cybercow wrote: 29 Sep 2022, 12:48 It's the same as if
No, it's not. How would it form a voltage divider if two pins are shorted (2 and 3 in this case)?
It forms a voltage divider with R23. It's not typical with C4 being between R23 and VR1, but that's how it works.
"Analog electronics in music is dead. Analog effects pedal design is a dead art." - Fran

User avatar
VivMeLol
Information
Posts: 37
Joined: 28 Oct 2019, 17:57
Has thanked: 18 times
Been thanked: 24 times

Post by VivMeLol »

Great tracing effort, Cybercow Mark Davis

Respects going out to you !

User avatar
JTEX
Information
Posts: 23
Joined: 27 May 2021, 13:31
Has thanked: 7 times
Been thanked: 60 times

Post by JTEX »

Inevitably, I ended up redrawing the whole thing to help me gain a better understanding of its workings. I'm leaving the drawing here in case it helps someone. Note that this is as-built by SR&D. For the sake of 'science", I didn't delete anything from the original (not even the active bypass or low battery indicator). Credit goes to Cybercow, and Robert at PedalPCB. I compared notes with their drawings.

I checked it thoroughly, but please let me know if you spot any errors.

-Jerry
Ultimatum_JC.png

Post Reply