# Duocast



## caiofilipini

After an issue with enclosure shorts, here's my latest build, the Duocast:









I used a BC549C in Q1 and an NOS GT2308 in Q2. I actually tried a few different transistors in Q2, including an OC71, an AC128, and a 2N404. The 2N404 and the GT2308 sounded better in my opinion, and I ended up choosing the latter. Very interesting pedal. I really liked it with my strat, but had a bit of a harder time dialing it in with humbuckers (Gibson SG). Still need to explore more.

The decal is a mess, I had a tough time getting it aligned and straight, but it is what it is. Design heavily inspired by by @joelorigo's build (hope you don't mind!).

My only real disappointment with this build is I bought a set of Neve marconi-style knobs, but they're a little too big, there's not enough spaces between the pots to fit them. I put these knobs in temporarily, but I'll definitely replace them at some point.


----------



## joelorigo

That's nice lookin' and I don't mind at all. I was "inspired" by the original ha ha.

I almost bought those knobs.


----------



## joelorigo

Also, I bought and installed the OC71 without any testing (because I don't have anything to test it on) and now I wish I would have socketed Q2 to try other transitors


----------



## SYLV9ST9R

Good job. Those Gorva boxes are so sleek.


----------



## caiofilipini

joelorigo said:


> Also, I bought and installed the OC71 without any testing (because I don't have anything to test it on) and now I wish I would have socketed Q2 to try other transitors



Yeah, and I kinda regret not doing the same thing for Q1, I think my BC549C is a little too grainy there. Oh well.


----------



## caiofilipini

SYLV9ST9R said:


> Good job. Those Gorva boxes are so sleek.



Thank you! I love the Gorva stuff.


----------



## TheSin

I wanted those knobs on mine too! Is that a 1590BB you fit it into?


----------



## caiofilipini

TheSin said:


> I wanted those knobs on mine too! Is that a 1590BB you fit it into?



It's a Gorva S90, which is slightly smaller than a 1590BB, but deeper (sort of like the 1590BBM, which is the one recommended in the build docs for the Duocast).


----------



## HousTom

Just finished mine using a *TI 2N404 *from Smallbear based on this post and because it was affordable and available.  Wow -- very happy with the result.


----------



## caiofilipini

@HousTom I really like that transistor as well, especially in treble boosters, but I think it's a great fit for the Duocast as well. Out of curiosity, what's the hFE on the one you used?


----------



## music6000

caiofilipini said:


> Yeah, and I kinda regret not doing the same thing for Q1, I think my BC549C is a little too grainy there. Oh well.


Try adjusting the Internal Trimmers, they have a big impact on the grit of the overall Gain!


----------



## HousTom

I honestly did not check the hFE -- just crossed my fingers and shoved it in there.  🤪


----------



## caiofilipini

I mentioned this in another thread, but just to close the circle here, after measuring reference voltages and transistor bias on a real Hudson Broadcast Dual, I started investigating my own build to try and figure out why it didn't sound any close to the demos and the real unit I had in my hands. Turns out I had my BC549C installed backwards, so the biasing of the transistors was all over the place!

I just fixed it and it sounds glorious now! And pretty darn close to the real thing. I ended up swapping Q2 out for a CV7003 with hFE ~60. Super stoked!

I'm about to receive a rev3 board, so I'm going to build a new one anyway, but it all makes sense now.


----------



## fig

caiofilipini said:


> I mentioned this in another thread, but


That's good news! Both that yours is fixed AND it's a true build!


----------



## caiofilipini

fig said:


> That's good news! Both that yours is fixed AND it's a true build!



Thanks!


----------



## music6000

caiofilipini said:


> I mentioned this in another thread, but just to close the circle here, after measuring reference voltages and transistor bias on a real Hudson Broadcast Dual, I started investigating my own build to try and figure out why it didn't sound any close to the demos and the real unit I had in my hands. Turns out I had my BC549C installed backwards, so the biasing of the transistors was all over the place!
> 
> I just fixed it and it sounds glorious now! And pretty darn close to the real thing. I ended up swapping Q2 out for a CV7003 with hFE ~60. Super stoked!
> 
> I'm about to receive a rev3 board, so I'm going to build a new one anyway, but it all makes sense now.


Curiosity has got the better of me here, Your BC549C is facing the right direction in the Picture above & Highlighted below :


----------



## caiofilipini

music6000 said:


> Curiosity has got the better of me here, Your BC549C is facing the right direction in the Picture above & Highlighted below :
> 
> View attachment 10963



Right, that's what I thought as well, but the ones I have use a different pinot (confirmed with a DCA55), facing the flat part it's CBE.


----------



## music6000

caiofilipini said:


> Right, that's what I thought as well, but the ones I have use a different pinot (confirmed with a DCA55), facing the flat part it's CBE.


Counterfits I reckon, from Tayda or Ebay ?


----------



## caiofilipini

music6000 said:


> Counterfits I reckon, from Tayda or Ebay ?



Not at all, I suppose, I got these ones from Pedal Hacker:









						BC549C Ferranti High Gain NPN Fuzz Silicon Transistor
					

BC549C Ferranti High Gain NPN Fuzz Silicon Transistor



					www.pedalhackerelectronics.com


----------



## Dan0h

caiofilipini said:


> Yeah, and I kinda regret not doing the same thing for Q1, I think my BC549C is a little too grainy there. Oh well.


I ended up with a Bc407b in my build and it really made a huge difference. The 549C is grainy, I agree.


----------



## jcrhee

music6000 said:


> Counterfits I reckon, from Tayda or Ebay ?


has there been counterfeits from Tayda?


----------



## caiofilipini

Dan0h said:


> I ended up with a Bc407b in my build and it really made a huge difference. The 549C is grainy, I agree.


Well, to be fair, it was completely off-bias due to being reversed, I like it a lot more now!


----------



## music6000

jcrhee said:


> has there been counterfeits from Tayda?


Members have had trouble with their Transistors!
I only get Potentiometers & Enclosures from them.


----------



## zgrav

I haven't had any issues with transistors from Tayda.  Also a good source for resistors and capacitors.


----------



## Betty Wont

zgrav said:


> I haven't had any issues with transistors from Tayda.  Also a good source for resistors and capacitors.


Agreed, they have no interest in having a reputation for selling bad parts. They are resellers just like any other parts source you would use. If they are notified of a out of spec parts, they pull and test right away. I've had far more bum parts from Small Bear than Tayda. I still use Small Bear, but they have a lot more vintage, NOS, and third party supplied parts which account for it. None of them are trying to hose you, but they can't test every piece or batch of every part.


----------



## Chuck D. Bones

music6000 said:


> Members have had trouble with their Transistors!
> I only get Potentiometers & Enclosures from them.


I've bought many a transistor from Tayda with no problems. The only bogus parts I got from them were some 1N34s and 1N270s a couple of years back that were obviously not Germanium.

Never had a bad part from Small Bear, but I know if it ever happens they will make it right.


----------



## music6000

The moral of this story is *TEST everything *before you mount it in your PCB !!!!!!


----------



## pi.cast

Hi Everybody,
I'm also building a duocast and ran into the same problem of the OP with my BC549C NPN transistor bearing a different pinout than the standard TO0-92 package. I've purchased my transistor from Mouser, so I'm sure it isn't a counterfeit. Also checking the datasheet, the pinout matches what is expected. So I think it is just the way BC549Cs are built.


----------



## Chuck D. Bones

That's correct.  Most, but not all, TO-92 BJTs are E-B-C.

BC549x is C-B-E.

I have some 2N5232A that are E-C-B.

Always pays to check the datasheet.  Any decent transistor tester will indicate the pinout.


----------



## caiofilipini

Yeah, BC183L are E-C-B as well.


----------

