Author Topic: Noisy Rhodes Sitting on top of Hammond  (Read 341 times)

Offline armstrongsound

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Noisy Rhodes Sitting on top of Hammond
« on: November 12, 2018, 02:32:31 PM »
What's up Rhodes-land.

So in my home studio, I am keeping my 1970 Rhodes Suitcase (top only) on top of my Hammond CV. As long as the CV is plugged into power at all (it doesn't have to be switched on), the Rhodes signal is pretty noisy (like a hum with a little white noise).

I had chimed in on an earlier post at the beginning of this year and Pnoboy suggested placing a sheet of foil between the piano and the organ and grounding the output to the foil.

I'll probably end up going that route, but surely I am not the first person to want to play their Rhodes and Hammond at the same time so I am wondering what other solutions might be out there!

1970 Fender Rhodes Mk I Seventy-Three Suitcase (no suitcase amp)
1968 Fender Vibrolux (aa864 circuit)
1947 Hammond CV
1947 Hammond DR-20
1970s Leslie 760
1969 Hammond T202
1956 Hammond S6
1982 Kustom 88
90s Young Chang Upright
Hohner Melodica

Offline sean

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Re: Noisy Rhodes Sitting on top of Hammond
« Reply #1 on: November 12, 2018, 03:18:13 PM »

Uhm... Go to grocery store, buy the widest roll of aluminum foil they have, take it home, roll out some foil wider than the Hammond, lift up the Rhodes, lay down the foil, get an alligator clip, and connect the foil to any audio ground, done.  What's not to love about pnoboy's solution?

If it doesn't work, then you can put the aluminum foil in the kitchen drawer, and forget about it.

If it works, then you are done.  If you want to make it cosmetically more elegant, then you can glue the foil to a layer of posterboard.
After you prove that the shielding works, if you want to make it more durable and complicated, you could use roof flashing, but you will risk cutting your fingers.

We assume that you have tried the Rhodes in another place somewhat far away from the Hammond, so you have proven that there is no interference when the Rhodes is a few feet away from the Hammond.  Right?  (Because if the noise is still there, then it would not be EMI, it would be noise coming through the AC mains from the Hammond to the Rhodes or to the amp.)

Sean

P.S. - I don't think it is worth the hassle to try to put the shielding inside the Hammond or inside the Rhodes.


« Last Edit: November 12, 2018, 03:22:28 PM by sean »

Offline armstrongsound

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Re: Noisy Rhodes Sitting on top of Hammond
« Reply #2 on: November 13, 2018, 10:40:13 AM »
Not that I don't love Pnoboy's solution. Just curious as to what other solutions others might have come across.

Yes, anywhere else and the Rhodes is crystal clear and quiet.

Thanks for the tips, Sean.
1970 Fender Rhodes Mk I Seventy-Three Suitcase (no suitcase amp)
1968 Fender Vibrolux (aa864 circuit)
1947 Hammond CV
1947 Hammond DR-20
1970s Leslie 760
1969 Hammond T202
1956 Hammond S6
1982 Kustom 88
90s Young Chang Upright
Hohner Melodica

Offline cinnanon

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Re: Noisy Rhodes Sitting on top of Hammond
« Reply #3 on: November 13, 2018, 11:21:52 AM »
I've heard of a similar problem with an Auto Vari drum synthesizer causing hum while sitting on top of a Hammond A100.  See below:

Owner: So I picked up an AV64 to use with my A100 and now I have a hum problem .I can make the hum go away by pushing the 16' pedal drawbar in or raising the AV64 a foot or 2 above the organ.

The AV 64 is sitting on Ken Rich straddles. Leslie kit is a 6122 to a 122. The 5u4 tube is pulled and I don't use the organ speakers at all, as it's connected like a B3 to the g-g terminals. The AV64 is playing thru a keyboard amp with no noise there The hum comes out the Leslie woofer.

I put put a layer of foil under the AV64 to no avail. Help please

Guy 1: Move the unit as far to the right as it will go. The hum is likely being induced into the matching transformer, which is on the left end of the organ, just under the top.

Owner: You are right. I moved it and it is overhanging the right edge by about 8 inches but the hum is gone. Thanks for the tip.

Guy 2: You said you put foil under the auto/vari. Try grounding the foil to the main amp with a clip lead and see if the hum goes away. My E-100 has foil mounted under the top of the organ which is grounded.Good luck, I hope you find the problem.

Guy 3: The typical tone wheel Hammond has a matching transformer on the upper left side (bass end) that is very sensitive to EMF that can be generated by transformers for example. Many older instruments caused hum when set on top of old Hammonds. The ARP string ensemble was one for example.

Shielding EMF is hard to do. Foil will shield RF but not EMF. The "shielding" needs to be thicker and have properties that in fact shield EMF, like mu-metal.

I had a church with horrible hum coming from the organ. Turns out an electric clock sitting on the left side was the culprit. Simply moving it to the other side eliminated the problem. This is the same reason placing a Leslie too close to the left side will cause hum.






Offline armstrongsound

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Re: Noisy Rhodes Sitting on top of Hammond
« Reply #4 on: November 13, 2018, 12:11:34 PM »
Cinnanon,
Thanks! This was extremely helpful. I am at work now, but am going to try a few orientations with the location of the transformer in consideration once I get home.


ALSO of interest, the CV has its own separate hum issue and referring to Guy 1 and Guy 3, the tone cabinet I am running through currently is RIGHT up against it on the left side. I wonder if that doesn't have something to do with it!

Thanks again for your input, this has been extremely helpful and I'll be posting back with results as soon as I get them.
1970 Fender Rhodes Mk I Seventy-Three Suitcase (no suitcase amp)
1968 Fender Vibrolux (aa864 circuit)
1947 Hammond CV
1947 Hammond DR-20
1970s Leslie 760
1969 Hammond T202
1956 Hammond S6
1982 Kustom 88
90s Young Chang Upright
Hohner Melodica

Offline cinnanon

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Re: Noisy Rhodes Sitting on top of Hammond
« Reply #5 on: November 14, 2018, 11:16:43 AM »
Thanks again for your input, this has been extremely helpful and I'll be posting back with results as soon as I get them.

Offline armstrongsound

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Re: Noisy Rhodes Sitting on top of Hammond
« Reply #6 on: November 15, 2018, 11:26:28 AM »
Lol, I had a impromptu jam session pop up in San Antonio last night after work SO TODAY for sure!!
1970 Fender Rhodes Mk I Seventy-Three Suitcase (no suitcase amp)
1968 Fender Vibrolux (aa864 circuit)
1947 Hammond CV
1947 Hammond DR-20
1970s Leslie 760
1969 Hammond T202
1956 Hammond S6
1982 Kustom 88
90s Young Chang Upright
Hohner Melodica

Offline armstrongsound

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Re: Noisy Rhodes Sitting on top of Hammond
« Reply #7 on: November 19, 2018, 10:29:28 AM »
So I've been extremely busy, but I had a chance to go ahead and check this out.

So unfortunately I am still getting a pretty instense hum no matter where I move the piano, until it's a good 6 inches above or away from any surface of the organ. Then the signal is nice and clean.

Also I tried moving the tone cabinet from the left of the organ to the right (and several other orientations) to try and see if that helped the separate issue with just the organ and still no dice. I do believe they are separate issues, although there isn't really any evidence to tell me that, it's more of a gut feeling that I have.
1970 Fender Rhodes Mk I Seventy-Three Suitcase (no suitcase amp)
1968 Fender Vibrolux (aa864 circuit)
1947 Hammond CV
1947 Hammond DR-20
1970s Leslie 760
1969 Hammond T202
1956 Hammond S6
1982 Kustom 88
90s Young Chang Upright
Hohner Melodica

Offline pianotuner steveo

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Re: Noisy Rhodes Sitting on top of Hammond
« Reply #8 on: November 21, 2018, 08:18:49 AM »
Try adding a ground wire to the chassis of the Hammond and grounding it to the ground screw on the wall outlet (as long as it is a properly wired 3 prong outlet)
Just be 100% sure there is no stray voltage on the Hammond chassis first.

That solved a hum issue I had with an old Wurlitzer.
1960 Wurlitzer model 700 EP
1968 Gibson G101 Combo organ
1975 Rhodes Piano Bass
1979 Wurlitzer 206A EP
1980 Wurlitzer 200A EP
1980 Wurlitzer 270 Butterfly Grand
2000 Yamaha acoustic piano
2004 Hammond XK3
2009 73A Rhodes Mark 7
2009 Korg SV-1 73
....and a few guitars...

Offline armstrongsound

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Re: Noisy Rhodes Sitting on top of Hammond
« Reply #9 on: November 27, 2018, 09:24:02 AM »
Steveo,
That sounds like something I'll try. The Hammond still has its two prong plug, though. Will that factor in here?
1970 Fender Rhodes Mk I Seventy-Three Suitcase (no suitcase amp)
1968 Fender Vibrolux (aa864 circuit)
1947 Hammond CV
1947 Hammond DR-20
1970s Leslie 760
1969 Hammond T202
1956 Hammond S6
1982 Kustom 88
90s Young Chang Upright
Hohner Melodica