Simulcast/Broadcast Silicon Mod?

We had a discussion about a similar filtering on the Marsh fuzz on another thread. Basically there is no reason for that…
 
HamishR said:
What's with the filtering? Why use a string of 10µF caps separated by resistors? I'm not being snarky! I just don't know why you would do that, and there is probably a very good reason of which I am unaware.
Click to expand...
It's how the charge pump works.
 
jesuscrisp said:
It's how the charge pump works.
Click to expand...
On second look, I only see R13 as potentially “extra”. The rest of the resistors are for voltage dividers and the caps for filtering. Debatable whether you need all of the caps but certain design decision also depend on the way the original PCB was laid out. And btw the charge pump does not use resistors so I don’t think @HamishR was referring to that section.
 
giovanni said:
On second look, I only see R13 as potentially “extra”. The rest of the resistors are for voltage dividers and the caps for filtering. Debatable whether you need all of the caps but certain design decision also depend on the way the original PCB was laid out. And btw the charge pump does not use resistors so I don’t think @HamishR was referring to that section.
Click to expand...
I think I misread that but also I don't really see a string of resistors and caps.
 
Sorry - got confused. Easily done for me. I've been looking closer at the schematic and now realise that the"string of resistors and caps" was indeed the diodes and caps for the charge pump. Don't mind me - I can be really thick sometimes!🤪

Time for a ride on my bike to clear my head.
 
Those little transformers have crap bandwidth and are rolling off some of the top and bottom-end. But I agree, as-designed it's 99% hype.

Hudson missed an opportunity to isolate the secondary from ground so that the Broadcast could also be used to break ground loops.
 
I am a recent convert myself. I totally was a sucker for the transformer magic, until I built the Heavy water clone and realized the “magic” was not the transformer in the Hudson after all. The Magic is when the circuit is just right and gels with the rest of your gear.
 
Dan0h said:
I am a recent convert myself. I totally was a sucker for the transformer magic, until I built the Heavy water clone and realized the “magic” was not the transformer in the Hudson after all. The Magic is when the circuit is just right and gels with the rest of your gear.
Click to expand...
What does the heavy water sound like?
 
I built a Heavy Water and was totally underwhelmed. But that's ok - most pedals are designed for somebody who is not me, I suspect. I didn't really go for the Hudson at first, but it does have something... As a boost the Broadcast is excellent, whether with the transformer or not. As Chuck suggests I suspect that the transformer is having a slight affect on the bandwidth - maybe it should have more effect because the Broadcast I built without the transformer sounds very similar to the stock form. I wish it rolled off a tad more high end!

The Heavy Water has little to no character of it's own through my setup. Whereas the Broadcast has a kind-of treble boost flavour that I seem to like. Everyone has their own take - maybe on a different day I would have liked the Heavy Water better.
 
FWIW I have ordered some 2N4033 transistors. If I can get a similar tone with silicon I will be happy - one less variable. I love the sound of Ge transistors but prefer consistency. And then to address that high end... Daeg's idea of the cap across base and collector of the BC549C works. I'm wondering if increasing the size of C2 might help?
 
Bumping this ol' thread:

If one were to build a Simulcast/Duocast circuit without a transformer on the existing PedalPCB board, would they need to install any jumpers on the PCB to bypass the transformer, or just leave a big gaping hole there?
I'm looking at the schematic, but not really understanding how transformers work, I'm unable to form any sort of hypothesis. Thanks for any help!
 
On the Simulcast, simply jumper T1-1 to T1-6. T1-1 connects to R14. T1-6 connects to pin-3 of the LEVEL pot.

Same thing with the Duocast.

I have some ideas on how to tame the highs, but have not tried them.

1. Increase C7. Will have the strongest effect at high GAIN settings.
2. Connect a cap from B to C on Q2. Start with 1nF. Too dark - make it smaller. To bright - make it larger.
 
I picked up a Source Audio EQ2 a few weeks ago and it’s been fantastic. I was easily able to tame the highs on the Duocast with it.
 
I followed Chuck's advice this time and put a cap across the base and collector of the 2N4033 transistor I have in one of my Broadcast clones - this one doesn't have the transformer yet still sounds wonderful! I used an 820pF MLCC because it was nearly 1nF and it fit better. And it seems to have reduced the highs a perfect amount for how I used the pedal.

Previously I did something similar on Q1 in another Broadcast on Daeg's advice and it worked there too. There are clever people here.
 
You must log in or register to reply here.

Similar threads

neiltheseal
Modify Simulcast to NPN
Replies
8
Views
505
airbud
airbud
G
Low Gain Silicon Transistors
2
Replies
37
Views
1K
Guilherme Collateral
Guilherme Collateral
VanWhy
Fuzz Cadet
Replies
0
Views
201
VanWhy
VanWhy
cylnplnt
Parentheses clipping mod w/jumper?
Replies
2
Views
188
cylnplnt
cylnplnt
A
Fuzz Captain bias / sustain
Replies
1
Views
378
Ajitator
A
Back
Top