Oscillators Leaking When Unpatched……In a Different Case

Discussing some incredible modules that don't quite fit into the other forum categories.

Moderators: Joe., lisa, luketeaford, Kent

Post Reply
jsheaucsb
Common Wiggler
Posts: 107
Joined: Fri Aug 07, 2015 4:21 pm
Location: Los Angeles

Oscillators Leaking When Unpatched……In a Different Case

Post by jsheaucsb » Tue Dec 18, 2018 3:35 pm

Have any of you ever experienced this? My 200e case has always been a bit noisy, so this year, I decided to put all non-e modules in a separate case.

I have a 24wls with all "e" modules [save for a 288v]. And I now have a 18wls which contains, among others, a 262v. The boats are grounded to each other with a banana cable.

What's strange is when I sweep the fundamental pitch knob of the 262v, there is a faint but definitive leak in the 24wls master audio out [a 227e]. Even when I disconnect the banana ground, the leak is still present.

I'm at a loss. How can a module with no audio jacks connected leak sound into a physically different case?

I'm hoping someone here might be able to help.

Thanks for reading!

User avatar
darcmorcel
Common Wiggler
Posts: 161
Joined: Sun Feb 17, 2013 12:20 pm
Location: South of France

Post by darcmorcel » Tue Dec 18, 2018 4:16 pm

I just read this today; not Buchla related but still might be a hint :

http://www.serge-fans.com/wizardry.htm

See the "General Wizardry and Things I found out the hard way" part of the page.

jsheaucsb
Common Wiggler
Posts: 107
Joined: Fri Aug 07, 2015 4:21 pm
Location: Los Angeles

Post by jsheaucsb » Tue Dec 18, 2018 5:03 pm

darcmorcel

Thanks for the link! Very interesting……could definitely be what's going on.[/b]

djs
Super Deluxe Wiggler
Posts: 1142
Joined: Wed Sep 01, 2010 8:36 am
Location: South Beloit, IL

Post by djs » Tue Dec 18, 2018 8:58 pm

Just for clarification- both cases are on the same power supply, correct? how are they connected to that power supply?
"Noise is what the Earth is made of" - David Bowie

jsheaucsb
Common Wiggler
Posts: 107
Joined: Fri Aug 07, 2015 4:21 pm
Location: Los Angeles

Post by jsheaucsb » Wed Dec 19, 2018 12:10 am

Each case has its own power brick. They were both connected to a Monster Power conditioner at the studio. I tried moving them both to a Furman unit in the studio and it made no difference.

I also tried placing the 262v in the middle and lower boats (it currently resides in the top most boat) and, again no change.

The Serge article is good food for thought. I tried using the tinijax outputs on the 227e by connecting them to an ES-8 (expert sleepers euro module) that connects via ADAT to my computer. The bleed was still there.

:hmm:

djs
Super Deluxe Wiggler
Posts: 1142
Joined: Wed Sep 01, 2010 8:36 am
Location: South Beloit, IL

Post by djs » Wed Dec 19, 2018 10:21 am

What if you move the cases to completely separate house circuits (different breakers, different rooms)... still interference?
"Noise is what the Earth is made of" - David Bowie

jsheaucsb
Common Wiggler
Posts: 107
Joined: Fri Aug 07, 2015 4:21 pm
Location: Los Angeles

Post by jsheaucsb » Thu Dec 20, 2018 6:03 pm

Thanks djs!

This test has provided some insight. In a different room on a different breaker, there's no interference. In the same room on a separate circuit., there's no interference.

In fact, if all cables are unplugged AND the ground banana connecting the two cases is unplugged, there's no interference.

There's only bleed if a Tinijax cable or banana cable is connecting the two cases. I always thought that the black connector in the back of the case is supposed to ground one case to the other. Am I wrong?

Still, its curious that only the 262v leaks when any cable is connected between the 2 cases [even when it itself isn't connected by a cable]

djs
Super Deluxe Wiggler
Posts: 1142
Joined: Wed Sep 01, 2010 8:36 am
Location: South Beloit, IL

Post by djs » Thu Dec 20, 2018 8:58 pm

jsheaucsb wrote: Still, its curious that only the 262v leaks when any cable is connected between the 2 cases [even when it itself isn't connected by a cable]
My bet is that the 262v is leaking through the ground. Grounding the two cases together via the banana jack isn't likely to fix this..
"Noise is what the Earth is made of" - David Bowie

Michael Tiemann
Common Wiggler
Posts: 57
Joined: Wed Jul 17, 2013 6:27 am
Location: pittsboro, nc

Re: Oscillators Leaking When Unpatched……In a Different Case

Post by Michael Tiemann » Sun Mar 08, 2020 8:59 pm

I have this same problem.

Michael Tiemann
Common Wiggler
Posts: 57
Joined: Wed Jul 17, 2013 6:27 am
Location: pittsboro, nc

Re: Oscillators Leaking When Unpatched……In a Different Case

Post by Michael Tiemann » Mon Mar 09, 2020 10:42 am

...And now I have fixed my problem! I bought a 3-prong plug ready to have wires screwed into it. I inserted only a ground wire. I bought a banana jack that I screwed to the other end of my ground wire. I plugged both of my 4-boat systems into the banana terminal of my ground wire, from each of the black ground Jack's at the back. Then I plugged the ground-only plug into the wall socket.

Not only did this eliminate the bleed of my 262v into the 225e (that was in a separate 4-boat system), but now everything actually sounds much, much better.

Victory!

TL;DR: plug each Buchla system's grounding jack into a common terminal wired to ground. Don't plug the two systems together using only a single wire between them.

maxl0rd
Common Wiggler
Posts: 62
Joined: Mon Aug 05, 2013 1:51 pm

Re: Oscillators Leaking When Unpatched……In a Different Case

Post by maxl0rd » Mon Mar 09, 2020 11:21 am

"You can trust your mother, but you should never trust your ground."

djs
Super Deluxe Wiggler
Posts: 1142
Joined: Wed Sep 01, 2010 8:36 am
Location: South Beloit, IL

Re: Oscillators Leaking When Unpatched……In a Different Case

Post by djs » Mon Mar 09, 2020 12:36 pm

Michael Tiemann wrote:
Mon Mar 09, 2020 10:42 am
...And now I have fixed my problem! I bought a 3-prong plug ready to have wires screwed into it. I inserted only a ground wire. I bought a banana jack that I screwed to the other end of my ground wire. I plugged both of my 4-boat systems into the banana terminal of my ground wire, from each of the black ground Jack's at the back. Then I plugged the ground-only plug into the wall socket.
This is a bad idea because you're basically covering up your system's power supply issue (or module issue) by just adding something on top of it. Also there is a severe safety issue with the ground-only plug. If you have a short on one of your boats, can the "ground wire banana jack" connection handle 15 amps/110v of house current?
"Noise is what the Earth is made of" - David Bowie

Michael Tiemann
Common Wiggler
Posts: 57
Joined: Wed Jul 17, 2013 6:27 am
Location: pittsboro, nc

Re: Oscillators Leaking When Unpatched……In a Different Case

Post by Michael Tiemann » Mon Mar 09, 2020 5:42 pm

Are you suggesting that my PSU could feed 120V@15A down the plug that's supposed to deliver 12V@8.33A? If so, I'm not sure that end of the PSU would do much better. Not to mention the Buchla itself.

As far as the boat side is concerned, it should only ever see 100w of power from the PSU. The wires in question can handle that.

User avatar
Graham Hinton
Super Deluxe Wiggler
Posts: 3161
Joined: Fri Jul 02, 2010 6:28 pm
Location: England
Contact:

Re: Oscillators Leaking When Unpatched……In a Different Case

Post by Graham Hinton » Mon Mar 09, 2020 5:49 pm

djs wrote:
Mon Mar 09, 2020 12:36 pm
This is a bad idea because you're basically covering up your system's power supply issue (or module issue) by just adding something on top of it.
No. He has correctly grounded the instruments as the manufacturer should have done. The issue was that they were not grounded.
Also there is a severe safety issue with the ground-only plug. If you have a short on one of your boats, can the "ground wire banana jack" connection handle 15 amps/110v of house current?
For a few ms for a trip to blow.
It is safer than having a floating system where you can touch the patch leads when that system becomes live through any fault. All modular synthesizers should be wired as Class I appliances because the user is in contact with the electronics.

The wire linking the two cases should be quite substantial to keep the resistance between the two 0Vs down in the milliohms and the wire to the mains Earth should be at least the same as in an IEC lead. The Earth wire should not be allowed to become an audio common to other equipment.

djs
Super Deluxe Wiggler
Posts: 1142
Joined: Wed Sep 01, 2010 8:36 am
Location: South Beloit, IL

Re: Oscillators Leaking When Unpatched……In a Different Case

Post by djs » Tue Mar 10, 2020 6:44 am

Wouldn't the better solution to be to fix the initial problem with the PSU/grounding, than adding a second wire/wall connection?
"Noise is what the Earth is made of" - David Bowie

User avatar
Graham Hinton
Super Deluxe Wiggler
Posts: 3161
Joined: Fri Jul 02, 2010 6:28 pm
Location: England
Contact:

Re: Oscillators Leaking When Unpatched……In a Different Case

Post by Graham Hinton » Tue Mar 10, 2020 8:14 am

djs wrote:
Tue Mar 10, 2020 6:44 am
Wouldn't the better solution to be to fix the initial problem with the PSU/grounding, than adding a second wire/wall connection?
He did the best solution given the handicap of an external bought in PSU.

Connection to the mains Earth pin should be with a separate wire directly to the 0V of the distribution system. It should not be done by connecting to the output of the PSU and sharing a wire to the distribution because there will be a voltage drop (DC + AC) along that. Any frame grounding that a PSU needs is a separate consideration.

The dubious practise of using an external bought in PSU is so that the manufacturer can avoid various regulations and certification costs and the liability. Such PSUs are not intended for powering complex audio systems.

Post Reply

Return to “Buchla, EMS & Serge”