DuoCast vs a real Broadcast

[jcrhee]

I think they sell it directly:

Item number 2N404A

T-PNP GE MEDIUM SPEED SW

www.ntepartsdirect.com

Datasheet says typical hFE is 86, but I guess you'd have to order a few and hope some fall within spec.

$8 to $9 in shipping -- ouch.

 

[TheSin]

A while back I built a DuoCast that didn't sound at all close to the Broadcast demos I'd seen. I tried a whole bunch of different germanium transistors, and they made some difference, but overall the pedal was lacking something.

So I bit the bullet and got myself a real Hudson Broadcast Dual. What a sound!

Anyway, I found and fixed an issue with my build (more on that here), so I decided to do a quick shootout against the Hudson:

You'll find this in the video description too, but my initial impressions are that the overall sonic characteristics are all there, even though there are some noticeable gain differences between the two, which likely boils down to the specs of each transistor.

Overall, I think the DuoCast sounds pretty cool!

Hope this is helpful.

Nice! Very close sonically to the real one. Thanks for sharing this!

 

[Chuck D. Bones]

I seriously doubt the gain difference is due to hFE unless you get a tranny with very low hFE. The R's & C's, mainly the GAIN pot and the two trimmers, set the gain of the circuit. Like Giovanni said, the tolerance on pots is huge, so that's most likely a contributor. Some trimmers have a reversed footprint, so don't go by trimpot position.

I've said it before, but I think it bears repeating: don't get hung up on part numbers, especially with Germanium. There is so much parametric variation within the same part number that you can build two Germanium circuits with the same part numbers and get drastically different results. The only things that matter are getting hFE and Icbo in the ballpark for the specific circuit. The boutique pedal builders frequently have to hand-select their Germanium transistors, diodes and FETs.

 

[music6000]

P

A while back I built a DuoCast that didn't sound at all close to the Broadcast demos I'd seen. I tried a whole bunch of different germanium transistors, and they made some difference, but overall the pedal was lacking something.

So I bit the bullet and got myself a real Hudson Broadcast Dual. What a sound!

Anyway, I found and fixed an issue with my build (more on that here), so I decided to do a quick shootout against the Hudson:

You'll find this in the video description too, but my initial impressions are that the overall sonic characteristics are all there, even though there are some noticeable gain differences between the two, which likely boils down to the specs of each transistor.

Overall, I think the DuoCast sounds pretty cool!

Hope this is helpful.

Alpha Potentiometers are all over the place, 1M that read as low as 920K, 100K that read as low as 89K and the list goes on!
TEST everything !
I've read somewhere that these PCB's are similar to the Pedal they are based on.
It gets down to the type & brand that of components used!

 

[HerrLanda]

A while back I built a DuoCast that didn't sound at all close to the Broadcast demos I'd seen. I tried a whole bunch of different germanium transistors, and they made some difference, but overall the pedal was lacking something.

So I bit the bullet and got myself a real Hudson Broadcast Dual. What a sound!

Anyway, I found and fixed an issue with my build (more on that here), so I decided to do a quick shootout against the Hudson:

You'll find this in the video description too, but my initial impressions are that the overall sonic characteristics are all there, even though there are some noticeable gain differences between the two, which likely boils down to the specs of each transistor.

Overall, I think the DuoCast sounds pretty cool!

Hope this is helpful.

Very Cool! I'm done with my build. Unfortunately no leds, no sound when engaged. When in bypass, sound comes through. The 9v/27v switch seems to be flawed. The switch stays in one position. It is moveable, but it will not stay in the other position (with a click). Could this be the problem? Thanks in advance!

 

[Erik S]

Very Cool! I'm done with my build. Unfortunately no leds, no sound when engaged. When in bypass, sound comes through. The 9v/27v switch seems to be flawed. The switch stays in one position. It is moveable, but it will not stay in the other position (with a click). Could this be the problem? Thanks in advance!

You'll get more help if you post a new troubleshooting thread with clear pictures.

Sounds like something is wrong with your switch, but I suspect something else is also going on. Even if your switch is stuck in one position you should be passing signal.

 

[HerrLanda]

You'll get more help if you post a new troubleshooting thread with clear pictures.

Sounds like something is wrong with your switch, but I suspect something else is also going on. Even if your switch is stuck in one position you should be passing signal.

I think I put my IC in the wrong way round... Rookie mistake . Naively didn't know about orientation... Still, not working. Probably fried it then? I will try to include some pictures soon. Thanks in advance

 

[HamishR]

I really like the 2N4033 in a Broadcast. It's the silicon transistor used in the Ariel Posen version. I got a bunch from Mouser and actually prefer the sound over the Ge transistors I have tried. I have made a few Broadcast pedals and now use the 2N4033 in all of them. Highly recommended.

 

[szukalski]

I think I put my IC in the wrong way round... Rookie mistake . Naively didn't know about orientation... Still, not working. Probably fried it then? I will try to include some pictures soon. Thanks in advance

The charge pump? They can be unforgiving to being put in the wrong way..