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Not Clear On Grounding
MUFF WIGGLER Forum Index -> Modular Synth General Discussion  
Author Not Clear On Grounding
Gringo Starr
Hello,

I haven't really mixed things together so Grounding has never been an issue for me to worry about. But now that I have a Kenton Pro 2000 and a few different cabinets I'm wondering how and what I have to ground.

First off do different 5U cabinets/power supplies need to be grounded together? I only have Moon Power Supplies except on my Modcan which is Modcan powered. Do I need to ground the Moon power supplies together? To the Modcan? I haven't grounded my Moon gear to my Modcan B yet and have had no problems. However I'm wondering if I still should.

My main concern is how do I know what needs to be grounded together? I was completely in the dark about needing to ground my Kenton 2000 to my modulars. And still a little unsure on how to do this. Only by chance did a recent thread mention this. Otherwise I wouldn't have thought of it. So how do I know what has to be and what doesn't need to be?

And as far as bananas are concerned. Can you stack grounds on top of each other? Maybe that question sounds crazy. Well that's how much I understand about grounding. Nothing! help help help
PrimateSynthesis
I'll try to keep this simple, rather than write a primer on grounding. Since you mention bananas, the simple answer to your question is yes, you should tie the grounds together at a common point.

What you want to avoid is multiple paths to ground that can cause ground loops.
Gringo Starr
PrimateSynthesis wrote:
, the simple answer to your question is yes, you should tie the grounds together at a common point.
.


What does that mean exactly? Tie the grounds together? I am and always have been an absolute handyman doofus. Hopefully this doesn't mean stripping down cords and literally tying things together. And so it's a "no" on stacking grounds?

Heres a story why I have a built in handyman fear from childhood if anyone cares. smile

My German grandpa was a handyman electrical genius. He was an Obermachinist for the German Navy in WW2. Just a brilliant man. Well one day when I was about 8 he gave me the head of a washing machine to take home and open up just for fun. Well he didn't show me how and expected that I was going to properly take it apart. I was just eager to see what was inside so I took it in the backyard and took a hammer and smashed the shit out of it til it opened up. In the meantime my mom called my Opa and had him listen to the racket I was making. They were both laughing hysterically at my lack of skills or lack of ability to trouble shoot. My Opa passed away just a few years ago and til the very end I was reminded and made fun of this event over and over. "You remember the hammer???". That's what he'd always say with his thick German accent. Hahaha... I think somewhere it scarred me. So now I have this built up fear of anything that involves tools. Other than putting together desks and tv stands I shudder at just about anything else. I'm convinced I will fail and make things worse.
Just me
Grounding is a black art. But an easy one to learn. Bananas? Stackables? Go for it. That will cover that. TS or TRS plugs take care of themselves. The sleeve is the ground. EURO, 5U, power supplies take care of grounding the modules. They will ground cabinet to cabinet by the cables. If everything has 3 prong mains cords and you aren't using those adaptors for older two wire recepticles, they will also ground to each other in some instances. ( the black art comes in at this point.)
If you have multiple cabinets and mutiple styles, the bananas will be the only concern. You need a ground from the banana system to the others. There is probably a jack for that. That would connect to the sleeve terminal of any jack on the other systems and you should be good to go.
Graham Hinton
Grounding in a complex system has three purposes: Safety, RFI screening and signal common. The larger the system the more difficult it is to be used for the signal common.

Forget RFI for now, as most modular synthesizers don't have proper screening. Digital DSP and microprocessor modules should, but don't.

Safety is the most important as you are holding patchleads in different hands that come from different equipment. Every PSU should be grounded via its mains cable and the mains ground should go through an RCD device in your building. Current only flows in the ground wire under fault conditions and this will cause the RCD to trip and disconnect your mains.

Normally the mains wiring will also function as a signal common, but sometimes the path will be too long. It is better to have short, higher current mains leads all going into the same distribution block than plugging into different wall outlets and relying on the long paths behind the walls. Some PSUs will also have terminals connected to the chassis and ground and these may be used to connect, or "tie", the PSUs together more directly with heavy gauge wire. It is better to have ground wires screwed down so that they cannot be accidentally disconnected when the equipment is on. No equipment should rely on obtaining its ground via a patched signal lead.

This may appear to be creating loops and eventually these will cause hums, the more equipment you connect together the harder it becomes to keep all the 0Vs exactly the same voltage. You cannot keep expanding synthesizers indefinitely with unbalanced signal connections, but you may get away with it up to a point. You will know when you pass it because you will start getting all sorts of hum problems as you change patching. Ideally all connections between different equipment should be balanced, like in a recording or broadcast studio, and by patching unbalanced between different powered equipment you are causing currents to flow in between the grounds which create voltage differences. Usually the monitor power amplifier provides the feedback to turn this in to a hum loop.
daverj
Graham Hinton wrote:
Every PSU should be grounded via its mains cable and the mains ground should go through an RCD device in your building.


There are no RCDs in houses in the US. Newer houses have a GFI (same basic idea) for the kitchen and for the bathroom. Either individual ones inside each outlet, or one combined with a circuit breaker in the breaker box for that circuit. There might also be one in a garage. The rest of the rooms seldom have a GFI, and there are no whole house RCDs/GFIs.

To the OP:

Since you live in the US, if the house has been wired or rewired in the past several decades then there's a good chance that the AC wiring has a reasonable common ground. Though it's better to rely on using a single outlet with power strips to have a common ground between equipment plugged in.

Any of your synths that have a 3 prong power cable and were correctly manufactured will most likely connect their chassis and signal grounds to the AC ground pin. So plugging those into the same power strip provides a common ground.

Synths that use TS style cables (1/4" or 3.5mm mono cables) carry a ground through the shield of the cable. So typically don't require an additional ground connection. (it won't hurt to have it, but it's not required for a signal connection).

Synths that use banana cables however do not carry a ground in that cable. So to connect them to another synth you need a common ground connection of some sort. If everything has 3 prong power cables then there's a good chance you are getting that ground connection there. But because of cable length it won't be as good of a ground as a direct connection.

If the system using bananas has an adapter panel to convert the bananas to TS cables as part of the banana box, then it is adding the ground there and you can probably get away without an additional ground. If you connect a banana cable from one box to another, or the adapter from banana to TS is in the TS based synth, then you will usually need to connect a separate ground wire between the two systems. Most banana systems have a ground jack for that purpose. Most banana to TS adapter panels in TS based systems also have a ground banana jack for that connection.

If you are connecting banana to a TS system and just using a cable with a TS plug on one end and a banana plug on the other, then you have no ground connection (other than possibly via the AC plug). So in that case you will need a banana ground jack added to the TS based system, or go through a banana to TS adapter panel that is grounded to the banana system.

Yes, you can stack a couple of ground bananas in a single banana ground jack. As long as they don't stack so high that they will fall out.
fireclown
I have been meaning to ask this question- Synton 3000 has a ground lug on the back as you might see on a stereo receiver, and I have no idea where and how to tie that down to the Doepfer G6 case I use to power my other banana modules (little bits of Serge and an ARP 4012 filter).
I would sure appreciate a little instruction on where and how to connect this ground lead from the back of the Synton to a Doepfer case.
Thanks!
daverj
fireclown wrote:
I have been meaning to ask this question- Synton 3000 has a ground lug on the back as you might see on a stereo receiver, and I have no idea where and how to tie that down to the Doepfer G6 case I use to power my other banana modules (little bits of Serge and an ARP 4012 filter).
I would sure appreciate a little instruction on where and how to connect this ground lead from the back of the Synton to a Doepfer case.
Thanks!


Option #1 = look inside the Doepfer case and see if there is a yellow and green striped wire connected to a screw on the side or back of the metal case. If so, that is an earth ground connection. If there is another hole next to that, which is unused, put a screw with a lockwasher through from the inside (a lockwasher is important), and then put a lockwasher and nut on the outside (so the thread is sticking outside the case. Make sure the screw is long enough to add a second nut.

Tighten the first nut quite tight to hold the screw in place. Then add a pair of flat washers and a second nut to the screw on top of the first nut. Don't tighten it. Then take a wire and strip both ends. Connect one end to the screw on the back of the Syntron and put the other end between the two washers on the Doepfer screw and tighten that second nut.

Option #2 = Carefully drill a hole in the back of the Doepfer case (be sure no metal shavings go inside, or you carefully clean them all up). Mount a binding post in that hole. Connect a wire to the inside post of the binding post (probably need to solder it) and connect the wire to one of the ground connections on the output of the power supply board (there's usually several there). You will probably need to crimp on a "Faston" or "Quick Connect" type of connector to the wire to push on that connector.

Now connect a wire from the screw on the Syntron to the binding post on the back of the Doepfer.
Gringo Starr
A big thank you to all of you who took the time and explained this.

THANKS! thumbs up
fac
Grounding is not what it used to be. You can't just lock your kids in their rooms because they'll spend the whole day on facebook or texting with their cellphones. These days, having the kids go play outside (and conveniently removing their cellphone batteries first) is enough punishment.

I hope that clears it up.
PrimateSynthesis
Gringo Starr wrote:

What does that mean exactly? Tie the grounds together? I am and always have been an absolute handyman doofus. Hopefully this doesn't mean stripping down cords and literally tying things together.


Although this has already been answered, just to be clear, "tie" means to connect electrically with a conductor. So if you were to tie the grounds of two banana-jack synths, you would connect to ground of one synth to the ground of the other synth with a wire.

The opposite of "tie" is "float".
Gringo Starr
PrimateSynthesis wrote:
Gringo Starr wrote:

What does that mean exactly? Tie the grounds together? I am and always have been an absolute handyman doofus. Hopefully this doesn't mean stripping down cords and literally tying things together.


Although this has already been answered, just to be clear, "tie" means to connect electrically with a conductor. So if you were to tie the grounds of two banana-jack synths, you would connect to ground of one synth to the ground of the other synth with a wire.

The opposite of "tie" is "float".


Thanks man. Much appreciated. smile
NewNewRon
With the arrival of my spiffy new Bugbrand synth voice I'm reviving this. Have read all the above and it seems mostly clear to me.
Would one of these - http://www.analoguehaven.com/cgproducts/pcv1/ - installed in each Eurorack case which would connect to the synthvoice suffice, if the 0v connection on both was tied?
Graham Hinton
NewNewRon wrote:
Would one of these - http://www.analoguehaven.com/cgproducts/pcv1/ - installed in each Eurorack case which would connect to the synthvoice suffice, if the 0v connection on both was tied?


No. That is a passive module with no internal connection to the 0V and the panels of Eurorack are not necessarily conductive or at 0V or mains Earth potential.

It is more important in an over-extended unbalanced system to have each section's 0Vs connected together by a very low resistance. The resistance of one banana cable is about 100 times higher than what is really needed.

Read this thread Validating grounds between two systems
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