Unfortunately the picture does not give hints at the values of the caps, since there is no side view.
Can you get more pictures?
A different approach would be to look for a Germanium Preamp design that has a silicon transistor in front of the Germanium + a Transformer at the output.
I am quite shure I have seen that preampd design somewhere before! Something looks very familiar.
After all it is Hudson Electronics, and like most others, they do not do (much) original designs.
Mostly copying and tweaks from vintage circuits.
It has been lifted from some Radio Mixer, hence the name "Broadcast", so we have to figure out which console they are talking about here...
Example: The Full Range Bomb is the Maestro FRB-1 - Full Range Booster
So if they are following their usual pattern, this approach would make sense...
I also want to build this, so I'll have a look around.
Hopefully we will figure it out with some collective effort.
I'm thinking its along the lines of the REDD 47 or the V72/RCA/Calrec/Gates preamps. They are all fairly similar and have similar controls as this pedal. Loads of schematics available for all the above. Could be an interesting project to even tackle one of those
That's a production product? They could have at least smoothed out the half holes on the edges I mean... I don't do that myself but I'm not making production pedals either. Anyway, looks like a cool circuit worth building.
During month i save my money to buy one of these toys. So i have this one there a couple month and I am delighted, it's a special one that is run with a charge pump 9v/24v. So this is what i have in the box. Just one question, what could be the diodes one the charge pump ?
Can you please take plenty of high resolution pics (post them to your Dropbox acc) of the front and back of both boards? I've followed your layout and tried to reverse a schematic from it but there are a few weird connections that I don't think are correct.
agree with ciaran, some of the connections don't make sense to me. if you can and ciaran can get the schematic i'll make a layout asap. don't mean to put pressure on you ciaran, but you do see to be the resident tracer here, i've only got a few traces under my belt, but you are just so damn fast and accurate. serious talent man.
That's a £5 transformer and explains the extra "5" in the £155 price tag! The vero layout is also one of the ugliest I've seen (considering it's a production pedal).
But if it sells...
This is, more or less, the circuit used for the charge pump:
Ciaran, I've heard a lot of great things about this effect... I think I also read a spread in Tone Report where someone reviewed the pedal and not only gave it the TR "editor's choice", but also had no "down-sides" to mention in that part of the review. Really eager to see how this comes out, and if they've really crafted something new or at least refreshing. Thanks for your efforts man!
Finally it's decoded!
Been hoping for this one for a while now...
Has anyone drawn up a schematic for this one yet?
Would love to see one, if it has been done already!
I am about to embark on building gear for my studio, and the old broadcast consoles are on the top of the list of stuff I would like to build.
Since I come from a pedal point of view, it seems like this would be a perfect starting point to get into understanding how these circuits are designed...
Thanks for your effort decoding this one and making a proper layout (damn! the original is messy/ugly!)
Thanks Ciaran! Greatly appreciated!
I see two value-differences when comparing it to the vero layout:
C7 is 1uf on the schematic and 1nf on the vero
C9 is 100uf on the schematic, and 10uf on the vero
...also: C14 and C15 seems like it's supposed to just one cap (100uf on the vero) as these will be in parallel when hooking up the B+ points
velouriafxs: my guess is that it work without, since it is a 10K:10K transformer (equal impedance on each side)
It will sound a bit different without the transformer coloration, but chances are that it will still sound good.
Try it and let us know!
Add a link/cable between pin 1 & 6 on the layout, and see what happens.
Then you can remove the link and add a transformer later if you want.
That way you will also get a pretty good picture of how the transformer colours the circuit as well...
I will add a 42TM018 until I get the Triad transformer, since I do not have the patience to wait before I build it + I want to hear the difference between them... (main difference is that the 42TM018 has about 3.4Khz frequency response and the Triad has 15Khz)