# Derpcast (Duocast)



## DAJE (Apr 6, 2022)

I think DERPCAST has to be the name of this one. 

Issues from the start (see Troubleshooting thread), and now it's done I'm just not that keen on it. But... I am very happy with how it looks, so it's worth a build report on that account. So here we are. Nice looking pedal that probably won't get much use.


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## szukalski (Apr 6, 2022)

Looks great. This was one that I didn't bond with immediately, high-end felt brittle, but then I gave it another shot with lower gain and stacked with a low-gain pre-amp and have kept it on the board. I favour it with neck humbuckers with the tone about half-way.

How are you doing the art?


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## DAJE (Apr 6, 2022)

szukalski said:


> Looks great. This was one that I didn't bond with immediately, high-end felt brittle, but then I gave it another shot with lower gain and stacked with a low-gain pre-amp and have kept it on the board. I favour it with neck humbuckers with the tone about half-way.
> 
> How are you doing the art?


I'll keep trying it, will dial the trimmers back a touch more, I think. Not writing it off just yet. 

The art is a sticker. These ones are quite thick and don't bend well, so I trim them to size and leave a bare metal "border" on the edges. I have some thinner and bendier ones that I also use for more complete coverage. I'm not much good with a pen and very bad indeed with paint, so I needed something I could work with. I could design something for Tayda to print, I guess, but I like the sticker method. The stickers are from AliExpress. I bought a bunch of them ages ago and have been working my way through them.


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## Dan0h (Apr 6, 2022)

These are amazing. I swapped in and out multiple transistors to find the magic spot. Also works much better as a pre-amp/boost vs a drive in my opinion. Adds all the lovely warm mids back to my chain. I imagine it’s not for everyone but it’s a pretty amazing pedal when you get it dialed in.


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## music6000 (Apr 6, 2022)

Dan0h said:


> These are amazing. I swapped in and out multiple transistors to find the magic spot. Also works much better as a pre-amp/boost vs a drive in my opinion. Adds all the lovely warm mids back to my chain. I imagine it’s not for everyone but it’s a pretty amazing pedal when you get it dialed in.


I have the Low Trimmer at 12.00 O'clock & High Trimmer at 10.00 O'clock, Low Cut at 9 to 10 O,clock
NOS OC71 & BC549C trannies!


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## MichaelW (Apr 17, 2022)

music6000 said:


> I have the Low Trimmer at 12.00 O'clock & High Trimmer at 10.00 O'clock, Low Cut at 9 to 10 O,clock
> NOS OC71 & BC549C trannies!


I'm starting to put together my parts list for this pedal. What hfe should I be targeting for the germanium PnP? (I know jack diddle about germanium transistors or fuzzy type components)


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## DAJE (Apr 17, 2022)

MichaelW said:


> I'm starting to put together my parts list for this pedal. What hfe should I be targeting for the germanium PnP? (I know jack diddle about germanium transistors or fuzzy type components)


The one I used is in the high 70s as I recall it. But Ge transistors are affected by temperature and pretty much everything else. So it could be anywhere between 50 and 100 depending on the test conditions.


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## jwyles90 (Apr 20, 2022)

DAJE said:


> The one I used is in the high 70s as I recall it. But Ge transistors are affected by temperature and pretty much everything else. So it could be anywhere between 50 and 100 depending on the test conditions.


Where did you get your Ge from? I have a couple laying around that are in that range but I'm not sure if they're specifically OC71s, so I'm wondering if it would make that huge of a difference.


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## DAJE (Apr 20, 2022)

jwyles90 said:


> Where did you get your Ge from? I have a couple laying around that are in that range but I'm not sure if they're specifically OC71s, so I'm wondering if it would make that huge of a difference.


OC71 is a part number, a specific part that was made in the days when Germanium was all there was for transistors. They still exist but there haven't been new ones made since the 70s or so. New old stock are rare and expensive if you can find any at all, because they're the same thing that was used in some classic legendary pedals. 

There's no functional difference between super mojo unobtainium legendary Ge trannies and former Soviet Bloc cheapies except the ex-commie ones are better made and less leaky. Anything in the right general range will work.


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## jwyles90 (Apr 20, 2022)

DAJE said:


> OC71 is a part number, a specific part that was made in the days when Germanium was all there was for transistors. They still exist but there haven't been new ones made since the 70s or so. New old stock are rare and expensive if you can find any at all, because they're the same thing that was used in some classic legendary pedals.
> 
> There's no functional difference between super mojo unobtainium legendary Ge trannies and former Soviet Bloc cheapies except the ex-commie ones are better made and less leaky. Anything in the right general range will work.


Ok awesome. I’m still wrapping my head around germanium as a component, so it helps to know that the range is more important than the part number. Thanks!


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## giovanni (Apr 22, 2022)

Since the start of the war I noticed a shortage of NOS Ge transistors on eBay. Thankfully I snatched a 100-box right before the war and they seem to be all in the 70-90 hfe range. If you’re lucky with ebay and own a transistor tester, that’s the way to go. Otherwise small bear still has a few but they are pricier.


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## MichaelW (Apr 30, 2022)

jwyles90 said:


> Ok awesome. I’m still wrapping my head around germanium as a component, so it helps to know that the range is more important than the part number. Thanks!


I just got my TG55/OC71's from this seller on eBay. Took a while to get here from Poland but all 10 of them check out good with Hfe's ranging from low 30's to high 80's. Now I need to see if I have all 35v min caps.......woohoooo....looking forward to building this!


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## MichaelW (Apr 30, 2022)

Arghhhh just realized I need a 1590BBM enclosure, which I don't have.


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## MichaelW (Apr 30, 2022)

Hmmmm found this thread where someone built it in a standard 1590BB and it fits......??


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## jwyles90 (Apr 30, 2022)

MichaelW said:


> Hmmmm found this thread where someone built it in a standard 1590BB and it fits......??


StompboxParts have 1590BBM enclosures if you’re in need of ordering some


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## DAJE (May 1, 2022)

MichaelW said:


> Hmmmm found this thread where someone built it in a standard 1590BB and it fits......??


I used the Tayda 1590BB2. 

I took the back off to check for you, and as you can see in the first pic, the transformer is poking out over the rim. There's a _little_ more room in there because the inner side of the back plate is recessed by a mm or so. So I don't _think_ the transformer is getting squashed and bending the PCB out of whack, but maybe it is. Tight fit, anyway.


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## MichaelW (May 1, 2022)

DAJE said:


> I used the Tayda 1590BB2.
> 
> I took the back off to check for you, and as you can see in the first pic, the transformer is poking out over the rim. There's a _little_ more room in there because the inner side of the back plate is recessed by a mm or so. So I don't _think_ the transformer is getting squashed and bending the PCB out of whack, but maybe it is. Tight fit, anyway.


Thank you for checking! @jwyles90 I was hoping I had all the parts to build it this weekend without having to wait for another order, but alas I was missing a couple of caps as well. So I guess I'll order an enclosure. @DAJE I have an old trashed 1590BB that I was going to drill some extra holes and test fit the board with the transformer. Might still do that. The enclosure was from my very first Paragon testbed in raw aluminum that I had drilled some seriously cattywampus holes in. I take it out and look at it from time to time when I need some humility......


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## DAJE (May 1, 2022)

MichaelW said:


> I have an old trashed 1590BB that I was going to drill some extra holes and test fit the board with the transformer. Might still do that. The enclosure was from my very first Paragon testbed in raw aluminum that I had drilled some seriously cattywampus holes in. I take it out and look at it from time to time when I need some humility......


I usually put a nut and washer on the toggle switch if there is one, so it's possible that the PCB could have been a mm or two deeper. Worth a try if you have a box anyway, and don't mind drilling. You could make a temporary box until you have the proper one.


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## MichaelW (May 2, 2022)

Well scratch that idea, guess I'm ordering a 1590BBM.


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## Harry Klippton (May 2, 2022)

MichaelW said:


> Well scratch that idea, guess I'm ordering a 1590BBM.
> 
> View attachment 25880
> 
> View attachment 25881


Too bad you drilled it already


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## lcipher3 (May 2, 2022)

You "can* mount it off board and it will fit




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						my "Atomic" Doucast - with 1590BB (off board transformer mounting)
					






					forum.pedalpcb.com
				










			https://forum.pedalpcb.com/attachments/dc1-jpg.4325/


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## MichaelW (May 2, 2022)

Harry Klippton said:


> Too bad you drilled it already


That was actually an old unused enclosure that holes drilled already. It just happened to fit the 4 pots for the DuoCast.


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## MichaelW (May 2, 2022)

lcipher3 said:


> You "can* mount it off board and it will fit
> 
> 
> 
> ...


I thought about that. How did you mount it? I was wondering if sticking it in a bed of hot glue would hold it in place, or GumWadz or something like that. I'm guessing it probably gets hot enough to melt hot glue?


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## Harry Klippton (May 2, 2022)

MichaelW said:


> That was actually an old unused enclosure that holes drilled already. It just happened to fit the 4 pots for the DuoCast.


Ah it's good to have some cadaver enclosures around


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## MichaelW (May 2, 2022)

MichaelW said:


> I thought about that. How did you mount it? I was wondering if sticking it in a bed of hot glue would hold it in place, or GumWadz or something like that. I'm guessing it probably gets hot enough to melt hot glue?



Ahh I see how you did it, you used the serial plate and bolted it together. Super cool! I'll have to give it some thought. I did order a 1590BBS but now I'm intrigued by the challenge!


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## HamishR (May 2, 2022)

I built the single channel version of this with a Russian MP20 Ge transistor and it works beautifully and is a favourite pedal when used as a booster into a low-gain OD. I generally only use low gain OD. Using this as a boost gives me that old-school warmth and sounds almost like a treble booster - the fattest, warmest, quietest treble booster of all time. I swap between it and a TI Boost (Dark Esbat) - both are excellent.

But I've had a lot of trouble with the dual version. The first one worked ok but I used a 3-way gain switch by mistake which made for some strange sounds. Then the second one I built I was painstakingly careful but get no sound at all. For the life of me I can't work out why.

I have one PCB left...


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