Darkglass - Duality Fuzz Engine  [traced]

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tommymariotti
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Post by tommymariotti »

Hi Guys,
yesterday a frind of mine give me a Darkglass Duality to try.
I just opened it and shoot some pictures.
It is based on 4049UBE CMOS.
All Pots are 100kB except for the Level Pot which is 100kA.


unfortunately I cannot hold the pedal so I will start tracing the pedal from the photos. In the next few months I will have the opportunity to have the pedal back in my hands and check all the connections. If someone has the pedal and wants to help me, you can write to me in PM.
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tommymariot
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Post by tommymariot »

Ok, I tried to trace the stomp box only from the pictures.
Here is what I found.

DG use the same flip flop used by Tech21.
The duality have some building block as in the B3k.

I'm not sure about the schematics. I have some doubt about the tone section. What you think?
I don't have the pedal at this moment so I cannot check some connections.
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Schematics V1 Unverified.pdf
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Post by skizoide »

Very interested in this one.

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jhergonz
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Post by jhergonz »

tommymariot wrote: 22 Jul 2021, 18:19 Ok, I tried to trace the stomp box only from the pictures.
Here is what I found.

DG use the same flip flop used by Tech21.
The duality have some building block as in the B3k.

I'm not sure about the schematics. I have some doubt about the tone section. What you think?
I don't have the pedal at this moment so I cannot check some connections.
The tone control looks like the treble control of Klon Centaur, it might be right.

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tommymariot
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Post by tommymariot »

jhergonz wrote: 12 Aug 2021, 17:36 The tone control looks like the treble control of Klon Centaur, it might be right.

Damn! You are right!!!!! :thumbsup
Now it's time to find the value of capacitors.

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Post by jhergonz »

for me, R1,R11 and C1 is more suspicious to me.

or maybe I just don't know if it why are they there.

looks like U3a should be non inverting amplifier,

R9 and C6 looks like it should be in the FB loop, and the R11 should be connected in Voltage ref and inverting input.

I'am just guessing here. it is hard to trace with just pictures. 😅

edit:

u3a is inverting gain stage.😅
Last edited by jhergonz on 14 Aug 2021, 16:59, edited 2 times in total.

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aion
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Post by aion »

R1 and C1 look like they should go on the inverting pin of the IC rather than the output, but otherwise everything else looks like it’ll work. I’m tracing one of these right now (including removing and measuring caps) so I’ll be able to confirm the rest before too much longer.

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Post by jhergonz »

aionios wrote: 14 Aug 2021, 16:23 R1 and C1 look like they should go on the inverting pin of the IC rather than the output, but otherwise everything else looks like it’ll work. I’m tracing one of these right now (including removing and measuring caps) so I’ll be able to confirm the rest before too much longer.
I hope we can hear more from you soon. 😁

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Post by tommymariot »

aionios wrote: 14 Aug 2021, 16:23 R1 and C1 look like they should go on the inverting pin of the IC rather than the output, but otherwise everything else looks like it’ll work. I’m tracing one of these right now (including removing and measuring caps) so I’ll be able to confirm the rest before too much longer.
Let me know, I will have the stompbox on my hands in the next months so I have to wait to check the connections.

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Post by aion »

Another discrepancy, and a pretty big one: U3A is actually an open-loop configuration, so pins 1 and 2 are NOT connected. I've never seen an open-loop opamp in the wild (although I've done it by accident myself) but that would make sense based on the sound of the gated fuzz path. If U3A was a unity buffer then the series diodes couldn't get anywhere near that sort of sound on their own.

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Post by jhergonz »

aionios wrote: 31 Aug 2021, 16:32 Another discrepancy, and a pretty big one: U3A is actually an open-loop configuration, so pins 1 and 2 are NOT connected. I've never seen an open-loop opamp in the wild (although I've done it by accident myself) but that would make sense based on the sound of the gated fuzz path. If U3A was a unity buffer then the series diodes couldn't get anywhere near that sort of sound on their own.
that makes sense, thank you ror sharing

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Post by tommymariot »

aionios wrote: 31 Aug 2021, 16:32 Another discrepancy, and a pretty big one: U3A is actually an open-loop configuration, so pins 1 and 2 are NOT connected. I've never seen an open-loop opamp in the wild (although I've done it by accident myself) but that would make sense based on the sound of the gated fuzz path. If U3A was a unity buffer then the series diodes couldn't get anywhere near that sort of sound on their own.
Ok.
Schematics updated!

Any news about R1 C1? can you confirm if is connected in the inverting pin?
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Schematics V2 Unverified.pdf
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Post by aion »

Yeah, I can confirm they go to the inverting pin.

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Post by tommymariot »

UPDATED!
I think it miss only capacitor values.
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Schematics Duality V3 Unverified.pdf
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Post by jhergonz »

thank you for sharing info.

I know this is not important,
but I'm just thinking, maybe the Pin 2 of the blend control should go to the pin 3 of q2?

I don't know if I'am correct, it just makes more sense.

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Post by aion »

All right, y'all were patient - here's the full schematic.

Darkglass Duality trace schematic
Darkglass Duality trace schematic

I believe the most recent schematic from this thread is accurate other than the missing capacitor values. The only structural difference is R11 in my schematic, which was not present in the unit I traced (revision 4-K) but was in the one from this thread (revision 7).

Since the resistor values all match up with mine, I think it'd be safe to backfill the Rev7 schematic with the Rev4K cap values and assume they're the same.

Full tracing journal:
https://aionfx.com/news/tracing-journal ... zz-engine/

PCB:
https://aionfx.com/project/binary-dual-fuzz/

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Post by jhergonz »

aionios wrote: 13 Nov 2021, 02:25 All right, y'all were patient - here's the full schematic.


darkglass-duality-trace-schematic.png


I believe the most recent schematic from this thread is accurate other than the missing capacitor values. The only structural difference is R11 in my schematic, which was not present in the unit I traced (revision 4-K) but was in the one from this thread (revision 7).

Since the resistor values all match up with mine, I think it'd be safe to backfill the Rev7 schematic with the Rev4K cap values and assume they're the same.

Full tracing journal:
https://aionfx.com/news/tracing-journal ... zz-engine/

PCB:
https://aionfx.com/project/binary-dual-fuzz/
thank you so much for sharing this information.

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Post by temol »

aionios wrote: 13 Nov 2021, 02:25 All right, y'all were patient - here's the full schematic.

Am I right that Blend and Filter potentiometers work the opposite way to the original? Full clean signal: Binary = max CW, Duality = max CCW. Filter, max treble: Binary = max CCW, Duality = max CW.

T.

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Post by aion »

Hmm, you're right. I didn't catch that in prototyping but it does appear those two are backwards. Thanks for pointing that out.

Here's the updated schematic -

Darkglass Duality trace schematic, v1.2 (11/28/21)
Darkglass Duality trace schematic, v1.2 (11/28/21)

Easy fix if you've built one already, just reverse wired 1 & 3 for both of those pots. If the direction doesn't bother you, the tone and taper is exactly the same, it's purely a "user interface" issue.

I've got a new version of the PCB on the way that will have this fixed, probably late December.

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Post by temol »

The fix to the existing build is easy (crossing the legs of the pots) but it does not bother me that much. I've already corrected my version of the schematic and the pcb layout for the next build. Btw - smd version of the 4049UBM (UBE or whatever Uxx) is not that easy to find locally.

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