Hudson - Electronic Broadcast

tipunk777 · Post by **tipunk777** » 30 Oct 2015, 14:21

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...

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

johnk · Post by **johnk** » 23 Dec 2016, 03:38

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:

aishabag23 · Post by **aishabag23** » 23 Dec 2016, 16:00

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

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

Manfred · Post by **Manfred** » 23 Dec 2016, 17:11

Where I can find the schematic of it.

johnk · Post by **johnk** » 24 Dec 2016, 00:58

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

johnk · Post by **johnk** » 24 Dec 2016, 05:16

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:

Manfred · Post by **Manfred** » 24 Dec 2016, 12:40

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

johnk · Post by **johnk** » 24 Dec 2016, 16:03

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

johnk · Post by **johnk** » 25 Dec 2016, 20:31

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:

fuzzbunny · Post by **fuzzbunny** » 25 Dec 2016, 21:46

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

johnk · Post by **johnk** » 30 Dec 2016, 07:49

i forgot one resistor in the above schematic!

here's the correct one:

aishabag23 · Post by **aishabag23** » 12 Jan 2017, 03:55

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!

gigelmargel · Post by **gigelmargel** » 11 Feb 2017, 20:27

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!

gigelmargel · Post by **gigelmargel** » 27 Feb 2017, 17:32

V1nce69 · Post by **V1nce69** » 15 Dec 2017, 15:48

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.

Hudson Electronics Brodcast 24V, PG Edition_vero layout.pdf: (68.24 KiB) Downloaded 491 times

If you have any questions feel free to ask. I took many pictures. I can post them later.

Vincent

V1nce69 · Post by **V1nce69** » 16 Dec 2017, 05:00

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

: gutshots and bottom plate

: gutshots

: main board top

: main board bottom

: power supply board top

: power supply board bottom

: potentiometers

: gain switch

: power supply V+ in

: power supply V+ out

: BC549C_v@collector

: BC549C_v@base

: BC549C_v@emitter

: MP200789_v@emitter

: MP200789_v@base

: MP200789_v@collector

plush · Post by **plush** » 29 Jan 2018, 09:45

Hi!

I can verify V1nce69's work.

teddeeh · Post by **teddeeh** » 19 Mar 2018, 12:54

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.

andy-h-h · Post by **andy-h-h** » 15 Aug 2018, 09:13

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

marshmellow · Post by **marshmellow** » 15 Aug 2018, 11:04

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.

Hudson - Electronic Broadcast [traced]