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humm from stacking another keyboard on top

Started by okdk, January 26, 2013, 02:38:39 PM

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okdk

When I place another keyboard on top of my Rhodes I get a pretty loud humm/buzz.  It goes away when I lift it up about 3 or 4 inches.  It happens with different keyboard, so I know it's not the keyboard, it's the Rhodes.  How do you deal with this?  Is there something to put in between to help?  Or do you have to raise it up?  I really don't want to raise it that much, it's too hard to play that way.  Does anybody have a solution?  Thanks!
'62 Hammond C3/leslie 122,  '74 Rhodes Stage 73, Vintage Vibe Legacy Classic 64, Yamaha Motif ES6, S90ES, Nord Electro 4

AFeastOfFriends

I think there's a thread somewhere in here that talks about this, but I couldn't find it after a little bit of searching. Anyways, the Rhodes is unshielded, so the noise you're having is the magnetic field of the other keyboard being picked up by the Rhodes' pickup. Similar to if you stuck a guitar right next to a laptop. You're going to be picking up some 'noise' produced by the laptop.

I had this problem too, so what I've done is take foil tape (mainly because I have a lot sitting around) or any other type of plated tape, and then cover the inside of the plastic harp lid with it, and then run a wire that I can easily plug/unplug down from the foil tape to ground on the harp. Keeps my Juno from making my Rhodes buzz.

Supposedly copper tape is a better conducter, but foil tape does just fine, and like I said, I had several rolls sitting around.

Cormac Long

Adding shielding to the harp cover may help. There's been mention of this before with people having encountered harp covers with the inner side lined with aluminium foil. The interference is less likely with modern synths but older analog synths are noise machines and the exposed wiring in a Rhodes harp is a sucker for interference.

On the Down the Rhodes DVD, George Duke was interviewed with a metal top rhodes in the background. This could have been a stacking mod but just as easily used to shield the Rhodes from interference.

Before you do anything however, check the grounding on the harp. Use a multimeter to test continuity between the RCA ground and the pickup tangs. Then do the same for the front aluminium strip and tonebars. The harp wiring and aluminium strip etc is designed to try and ground everything. Its not a perfect solution and many have found that quite a number of tone bars may not have this grounding working. I measured about 15 of my 88 with no continuity to ground. If you find a lot of the tonebars are not grounded, then its worth reseating them after cleaning the spring and strip etc to make sure they make contact between the tonebar and strip.

If the grounding tests come out good, then next up is a ground wire to the sustain bar if one is not already there.

Finally.. try to add a shield on top of the harp by running a sheet of aluminium foil along the top of the harp under the additional keyboard. That alone might work but I'd think you will also need to run a wire from the sheet to the RCA ground. If you get somewhere with this, then the solution is to sandwich foil between two sheets of cardboard and use that as a performance shield for the interference. You could also try to line the inner cover with foil.

I've noticed no problems with mine when I stacked another modern synth. That said, a fluorescent lamp that sits about 3 feet above the piano does induce a buzz when turned on. I also once put my laptop on top and it caused lots of interference. So even when you seem to have a quiet setup, it will still induce interference if the source is strong.
Regards,
   Cormac

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vortmaxx

I had the same problem when I put my laptop or my Nord on top of my piano. It obviously wasn't a big deal to move the laptop off to one side, but I really like having the Nord on top for gigs. The hum is not really noticeable when playing, but it definitely is in between songs, or when I am playing at home. I've learned to turn the volume down on the Rhodes when we are in between songs, but I recently set out to locate and hopefully alleviate the problem.

This is one of the threads I found to be very enlightening, which also has links to a few other very informative threads:
http://ep-forum.com/smf/index.php?topic=6273.0

Some really good stuff there, as always. I still have some trouble shooting to do, but I'm fairly confident that I will find the answer somewhere in these threads.

The Real MC


okdk

Thanks for the responses.  I'm sure this is a problem lots of people have experience with.  I get the same hum from my 2006 Motif ES as I get from a 1982 Roland Juno 60 which I just picked up.  I'll check the grounding.  I like the idea of covering a piece of cardboard with alum foil and placing it under the keyboard.  I hope that does something, will try it and let you know.
'62 Hammond C3/leslie 122,  '74 Rhodes Stage 73, Vintage Vibe Legacy Classic 64, Yamaha Motif ES6, S90ES, Nord Electro 4

okdk

Just by putting a large sheet of alum foil under the Roland eliminated almost all of the hum/buzz.  That's way too easy!  Now I'll try something more permanent like the foil tape that's been suggested.  Thanks again forum, what a great resource this is.

By the way, this Roland Juno 60 is awesome.  It wasn't exactly what I was looking for, but what a great sound.  I even found an old cv pedal I had stashed away from who knows when that really makes it fun.
'62 Hammond C3/leslie 122,  '74 Rhodes Stage 73, Vintage Vibe Legacy Classic 64, Yamaha Motif ES6, S90ES, Nord Electro 4

Cormac Long

To be fair, we kind of have to thank Michael Faraday.. http://en.wikipedia.org/wiki/Faraday_cage he came up with the idea originally :)
Regards,
   Cormac

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admin@ep-forum.com

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