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"Format Jumbling" and Grounding
MUFF WIGGLER Forum Index -> Buchla, EMS & Serge  
Author "Format Jumbling" and Grounding
syncretism
Is a grounding/common jack strictly needed for 1/4" to banana conversions? I see that the dotcom Banana Interface module doesn't have one, so I wonder if the jack I see on various "format jumblers" is there for banana devices that don't otherwise share a common ground (e.g. between power supplies), and that the ground provided by a TS jack is sufficient when connecting Euro, Frac or 5u modules.

Some clarification here would be gratefully received. Thanks!
jo__dem
from my understanding the ground jack on format jumblers are for banana devices that dont otherwise share a common ground.
syncretism
Like a Kilpatrick Phenol and a Serge. Makes sense. Thanks!
ArguZ
You have to obey 3 rules.

1. Electricity always needs two wires...signal and ground.
2. Voltages should not exceed the systems operating range
3. Negative voltages can kill

So without a GND no potential occurs. If there is no zero, there is no 10.
Jacks carry the ground in every cable, or actually the potential reference..
It can also be -2V or whatever, the difference is what counts.
The shared ground is great to prevent that...its the same reference for all.

When you are using Euro or Serge you normally think in 5V potentials.
That is half of what Buchla needs and even less than older formats produce.
And then be aware that Euro also goes negative, and some older parts if not protected by diodes etc can simply pop when presented with negative voltage.
To be on the safe side, use a Synovatron CVGT1 at first.
the bad producer
ArguZ wrote:
... 3. Negative voltages can kill...


Buchla Dead Banana
syncretism
ArguZ - thanks. It’s all Serge and similar here, as the banana stuff goes.
mutierend
I think the banana connectors on the Dotcom format jumbler were more intended for Modcan A than Buchla.
syncretism
mutierend wrote:
I think the banana connectors on the Dotcom format jumbler were more intended for Modcan A than Buchla.


I think I understand your point, finally. If you gave Modcan A operating off the same power supply as Modcan B or Dotcom, the Q121 likely doesn't need a common jack.

It just doesn't work like that with Serge for me; I think I'm going to have to solder the sleeve points together and fish them out to a common jack I'll install behind my Box 4. If I don't have a common jack (as my standalone jumbler does), I see what looks a lot like 60-cycle hum in my Gate Math when I'm clocking it from, say my Serge Timegen Clock.
Sir Ruff
Can I toss in a side question: how does one ground panels from separate makers that are running off different PSUs and don't contain grounding jacks? I.e., a Loudest Warning panel + Random Source?

Is this possible, or would it just be a better idea to run everything off of a single PSU?
Graham Hinton
syncretism wrote:
so I wonder if the jack I see on various "format jumblers" is there for banana devices that don't otherwise share a common ground (e.g. between power supplies), and that the ground provided by a TS jack is sufficient when connecting Euro, Frac or 5u modules.


No. The factor you are not taking in to account is the resistance of the wiring. All unbalanced equipment connected together needs a mains Earth for safety and a common 0V between all the different power distributions. That is two connections in parallel, but the 0V one should be much lower resistance. As mains leads and signal cables have resistances in the 100s of milliohms that means you are looking at achieving connections in the single milliohm range or lower. It can be done, but not with a banana lead.



Sir Ruff wrote:
Can I toss in a side question: how does one ground panels from separate makers that are running off different PSUs and don't contain grounding jacks?


Panels don't run off PSUs and should really be connected to mains Earth (called Ground in US). Module circuitry should share a common 0V (incorrectly called ground in most places). The lacking of understanding of the difference between them is what causes a lot of problems in most synthesizer systems.

The pro audio industry got its act together around 1995 whereas synthesizer makers are still copying discredited practices from the '60s and '70s. This causes problems when the two come together.

Quote:

Is this possible, or would it just be a better idea to run everything off of a single PSU?


Whatever size single PSU you have there will always come a point when you need another. What you need is a power and distribution system that scales up. No sane audio engineer would make a modular expandable unbalanced high impedance system and expect it to run on a cheap PSU through a DC barrel jack. You need some sanity, but that will require some rebuilding.
syncretism
Sir Ruff wrote:
Can I toss in a side question: how does one ground panels from separate makers that are running off different PSUs and don't contain grounding jacks? I.e., a Loudest Warning panel + Random Source?


Are you talking about a third prong in a plug, or the "common" jack? I've yet to see a power supply from STS, R*S, Konstant Labs or LW that didn't have both of those.
Sir Ruff
syncretism wrote:
Sir Ruff wrote:
Can I toss in a side question: how does one ground panels from separate makers that are running off different PSUs and don't contain grounding jacks? I.e., a Loudest Warning panel + Random Source?


Are you talking about a third prong in a plug, or the "common" jack? I've yet to see a power supply from STS, R*S or LW that didn't have both of those.


Yes, exactly, I was forgetting about this!
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