Hudson - Electronic Broadcast  [traced]

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tipunk777
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Post by tipunk777 »

Hello.

I'm a new user of this forum and a french guy, so excuse me if my words are not precise.

I'm looking for this pédal... Image
Image

They say that is inspired by an old RCA broadcast mic preamp. Did anyone have anything about it ?

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johnk
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Post by johnk »

i have the 9V version but added a charge pump to make it run on 18V internally.
the original is built on veroboard, but here's my PCB layout for it:
Attachments
01-Broadcast Layout.png

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aishabag23
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Post by aishabag23 »

The guys over at TagboardFX have done a few vero layouts of this one:

http://tagboardeffects.blogspot.com/201 ... dcast.html
Loe Sounds

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Manfred
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Post by Manfred »

Where I can find the schematic of it.

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johnk
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Post by johnk »

i drew up a schematic for my 9V version today. it's the one with the trimpot for the high gain.

Image

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Post by johnk »

just an FYI. i built both versions (the newer 24V version and the original 9V version which i own) and i like the original 9V version running on 18 or 24 volts better, so i drew up another PCB & built the older version and it sounds identical to my original.

here's the PCB layout for the one that i prefer:
Attachments
01-Broadcast 9V Layout.png

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Manfred
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Post by Manfred »

I have a further question.
Are gain selections of the transistor needed?

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johnk
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Post by johnk »

i've tried OC44's, OC71's and OC 75's and all of them sound pretty much the same.

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johnk
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Post by johnk »

i just finished my polished & etched 1590B early version 9V Broadcast (with internal 25V charge pump), with all top jacks and a relayed true bypass:

Image

Image

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fuzzbunny
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Post by fuzzbunny »

Great work John K.! (as always...)

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Post by johnk »

i forgot one resistor in the above schematic!

here's the correct one:
Attachments
Broadcast schematic 1200 .png

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aishabag23
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Post by aishabag23 »

johnk wrote:i just finished my polished & etched 1590B early version 9V Broadcast (with internal 25V charge pump), with all top jacks and a relayed true bypass:

[ Image ]

[ Image ]
Just perfect!
Loe Sounds

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gigelmargel
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Post by gigelmargel »

Hello!

Anyone can post the voltages of the transistors, mainly the ones of OC74?
I have only some AC128s and I want to know if are biased right or not.

Thank you!

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gigelmargel
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Post by gigelmargel »

:scratch:

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V1nce69
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Post by V1nce69 »

johnk wrote:i drew up a schematic for my 9V version today. it's the one with the trimpot for the high gain.

[ Image ]

I just traced my Broadcast 24V. I unsoldered all diodes on the power supply board to be sure of the type. I made an true to the original vero layout and measured the voltages on both transistors.
If you have any questions feel free to ask. I took many pictures. I can post them later.

Vincent

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V1nce69
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my favorite amplifier: Ampeg
Completed builds: Veroboards builds:
Throbak Overdrive Boost
Wampler Ecstasy
Creepy Fingers Doomidrive
Black Arts Quantum Mystic
Roger Mayer Voodoo Bass
Idiot box Blowerbox
Hudson Sidecar

Pcb builds:
Fulltone 69 (GGG kit)
Russian Big Muff (Musikding kit)
EHX Bassballs (home etched using Topopiccione layout)
BJFE BBOD (home etched, thx FSB)
Triangle Muff (Guitar PCB board)
Deluxe Bass Fuzz (home etched,gausmarkov.net layout)
Clone Theory Chorus (Celeste pcb from lectric-fx)
Cornish G2 (home etch, layout thx FSB)
Shin-Ei FY-2 Ge version (home etched, own layout)
Klon (Aion Refractor pcb)
Mutron Phasor II (home etched, layout thx JohnK)
Sunny-T (pcb by guitar pcb)
Rocket Overdrive (pcb by Pepers' pedals)
Sonomatic Deluxe Tape Delay (pcb by Skidmark)
Black Arts Quantum Mystic (adapted storyboardist layout)
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Post by V1nce69 »

I just traced my Broadcast 24V. I unsoldered all diodes on the power supply board to be sure of the type. I made an true to the original vero layout and measured the voltages on both transistors.
The attachment Hudson Electronics Brodcast 24V, PG Edition_vero layout.pdf is no longer available
If you have any questions feel free to ask...

Vincent
And here are all the pictures:
front view
front view
gutshots and bottom plate
gutshots and bottom plate
gutshots
gutshots
main board top
main board top
main board bottom
main board bottom
power supply board top
power supply board top
power supply board bottom
power supply board bottom
potentiometers
potentiometers
gain switch
gain switch
power supply V+ in
power supply V+ in
power supply V+ out
power supply V+ out
BC549C_v@collector
BC549C_v@collector
BC549C_v@base
BC549C_v@base
BC549C_v@emitter
BC549C_v@emitter
MP200789_v@emitter
MP200789_v@emitter
MP200789_v@base
MP200789_v@base
MP200789_v@collector
MP200789_v@collector

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plush
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Post by plush »

Hi!

I can verify V1nce69's work.
Attachments
wtf.jpg

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teddeeh
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Post by teddeeh »

Heres a couple of photos i have found of the dual footswitch.
Sadly no underside but could be worrh an experiment or two in decifering this layout, as wehave the original one to go from and fundamentally they are the same.
A778CDAB-7E76-4FB2-B512-9E3F83B15AFD.jpeg
2F6D99F8-FF82-47CF-80B2-43BD9A2C8422.jpeg

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andy-h-h
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Post by andy-h-h »

Can this be built without the transformer? It looks like it's just acting as decoupling / isolation device.

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marshmellow
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Post by marshmellow »

Yes, you can build it without the transformer. But it's not in the circuit to provide isolation (as drawn it doesn't), it is there to form the sound. In comparison to an overdriven guitar sound, transformer distortion is very subtle, its contribution might be minimal anyway. These little transformers usually also have very limited bandwidth, so to mimic the sound of the original pedal, you will probably have to introduce at the very least some bass cut.

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