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]

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]

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]

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]

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]

I mentioned this in another thread, but

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

 

[caiofilipini]

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

Thanks!

 

[music6000]

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]

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]

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]

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]

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.