Hum and hiss on a Rhodes Stage 73 Mk II

[funkster]

I recently noticed that my Stage 73 Mk II seems to have more of a hum and more hiss than it used to have. I noticed this when A/B -ing a recording I did recently with one from about 18 months ago, which seems a lot cleaner.  I could try filtering it out, as neither hum nor hiss  is  overpowering,  but would prefer to get as pure a sound as I can, for recording. I don't want to continue doing lots of recording with a sound I found later I could have improved.

The hum is somewhere around 110Hz,  - it does not sound like an earth-loop (in the UK) , I think. Both the hum and especially the hiss were accentuated by my use of a Major Key Harmonic Clarifier (i.e. the process  and the low-frequency boost knobs), but I have eliminated that as the cause by taking the signal straight out of the RCA output on the harp. The hum and hiss are still there.

I have tried running the signal through a DI box with an earth-lift, with no difference. (I've got a Wurlitzer with some kind of earth hum, and remove that with the DI Box). Touching various parts of the piano makes no difference. I have tried playing the piano through an ordinary keyboard amp, rather than through my small mix-desk/computer etc, but it is the same. Also switching off lights, computer screen etc.

The only thing that did stop the hum, but not the hiss much, was lifting up the front of the harp to an angle of 45 degrees (which is not helpful, of course). Strangely, the hum came back the closer the harp was angled to 90 degrees.

I have seen several other lengthy threads here about hums and buzzes, and will try some of those recommendations, but thought I would put the specifics of my problem here, in case anyone has any definite ideas.

I keep the Rhodes on a large shelf, rather than using the legs, - don't know if that's at all relevant for grounding concerns.

It's possible I am just noticing the hum and his more than I used to, or had the output/input  levels  of the piano and mixer set up differently, but I don't think so.  But in any case, I'd like to get rid of it.

[Cormac Long]

One thing that some models had was a ground cable from the RCA to the aluminium damper bar. Lifting the harp away from that probably counteracted the effect.

Try to connect a wire from the RCA ground to the damper bar to see if it solves the issue.

[SWANG]

One thing that some models had was a ground cable from the RCA to the aluminium damper bar. Lifting the harp away from that probably counteracted the effect.

Try to connect a wire from the RCA ground to the damper bar to see if it solves the issue.

mine has this.  when i first bought it, the ground wire had fallen loose.  for a while, i wondered why the volume was so low even when i cranked my amp.  i also had serious hiss and hum.  after asking some question on the old site, i finally reattached the ground cable to the damper and presto!  the volume level instantly increased, the hum went away, and the hiss is now minimal (if not inaudible). 

[sean]

Take a good look at the cleanliness of your RCA jack.


Very interesting that you noticed that a certain orientation of the harp eliminates the hum....