Treble and mid-range level, radio noise

[tagirov]

Hi guys.
I've got 1977 73-key Rhodes MK I Stage Piano in December 2015 and now want to do some basic service and adjustments of the instrument.
It seems that there are no pro e-piano technicians in my area (Yekaterinburg, Russia) and I will have to service the piano myself.

It's in good condition, all hammers and tines are in place and work, pedal action is normal, bass boost and volume controls aren't noisy and so on.
But it's not perfect as well. Some tines need tuning and some key action could be better, some areas sound louder than others.

Three are things I want to fix first:

1) Treble area is much louder than mid and low range. May it be fixed?

2) Some part of mid range  (from Middle C = C4 to C5) sound a bit quieter than expected.

3) I hear radio noises when connect my piano to a preamp or amp. It's always there even when I'm changing different preamps or amps.
Sometimes radio is louder, sometimes quieter, but it's always there.
Are there any modifications or common ways to fix it?
Now I have to use gate plugin in my DAW on recorded Rhodes tracks to get rid of radio noises.

I usually don't connect Rhodes directly to HI-Z input of my UAD Apollo Quad and don't use DI.
I prefer connecting it to ENGL Tube guitar Preamp E530 which is connected to Apollo's line input.
Sometimes I plug my Rhodes into Laney VC15-110 with external Marshall 1960 4x12" cabinet when recording Rhodes with microphones.
Sounds great both ways, but radio noise is always present.
And preamp/amp tone controls do not help with treble/mid range loudness problem, even though it changes the tone.

I also plan to order Vintage Vibe preamp and Miracle Mod, but later this year, any recommendations, what I have to check before ordering?

[pnoboy]

All the issues you have with some notes being too loud or too soft, in general, can be addressed by proper adjustment of the action--specifically the position of the pickups with respect to the tines.

The radio noise may be a bit more difficult to address.  Does the radio noise go away when you turn the volume control all the way down?  That's an important question.

[David Aubke]

As pnoboy said, irregular volume levels are typically corrected by adjusting the pickup to be closer or farther from the tine. You might also check that all of your pickups are working by tapping each magnetic slug with a screwdriver or other metal object.

I don't know how best to address the radio interference. Sometimes people have resorted to applying shielding to the underside of their harp cover but I don't know how effective that is. Given that the Rhodes consists of all single-coil pickups, I think interference is sometimes unavoidable and best addressed by removing the source.

[The Real MC]

I can confirm that shielding under the harp cover does nothing.

You might want to try a separate DI box with very high input impedance, at least 1 meg ohm.  Plug it in right off the harp RCA jack, not the output on the numeral.  I got the best tone and quietest signal using a Countryman Type 10.  The rhodes pickups are very sensitive to different loads.

[tagirov]

The radio noise may be a bit more difficult to address.  Does the radio noise go away when you turn the volume control all the way down?  That's an important question.

Yeah, thanks! That IS important question, I had to think about it first, how stupid am I!
I checked it today.

So, the radio noise is present even when I turn the volume knob all the day down.
But it disappears when I plug out my cable from the Piano.
I tried changing cables, but it doesn't work - when I plug a cable into the Piano, I hear the radio from my speakers.

More experiments tomorrow, with DI and another different cables.
Maybe I have to change the cable between the preamp and the UAD Apollo.

p.s. The problem is that our studio is located right under TV Broadcasting Tower (we rent an old soviet broadcasting facility at regional TV station, the studio was built in 70s or 80s for concerts, folio recordings and so on and recently converted to music recording studio).

I believe that the radio comes from the TV tower. Sadly, there are only three or four devices in our studio which receive the radio noise: the Rhodes piano, the Stratocaster, one of two Neuman u89 mics and something else, don't remember

[pnoboy]

Given that the noise is still present with the volume control all the way down, we know that the radio noise is not coming from the pickups in the usual way.  Either the small length of unshielded wire from the phone jack to the volume pot is enough of an antenna to pick up the radio interference, or the noise is common-mode noise.  You could try the following experiment.  Take an ordinary phone jack, and connect a loop of wire perhaps  10 cm in diameter, between the center contact and the ground contact.  Then plug it into the cable that you normally use to connect to the Rhodes.  Do you hear the radio noise?

[tagirov]

I tried some things today.
1) different cables from Rhodes to a preamp (EGNL 530) - radio noise is present
2) different cables (balanced/unbalanced) from preamp to UAD Apollo's line input  - radio noise is present
3) Rhodes directly to UAD Apollo HI-Z input, input gain all the way up - no radio noise
4) cable loop to the preamp as pnoboy said - radio noise is present
5) Rhodes to active phantom powered DI connected to Nagra 4.2 preamp which is connected to UAD Apollo, Narga input gain all the way up - no radio noise.

It seems that the problem is the ENGL preamp, will check it later for ground issues, etc.

Thanks all for your recommendations and opinions.

[sean]

So the devices with a high-quality power supply eliminated the noise.

Maybe the ENGL can be saved if you plug it into a "power conditioner,"  "AC line filter," or "hum eliminator."

You could also try using a ЧЕТРА T40 to take out the antenna.

[pnoboy]

The fact that a small shorted turn picks up the radio station confirms that there's a strong signal.  The r.f. is getting into the preamp, where it's  being rectified, and that's why you hear it.  Bipolar transistors are notorious for this, though I gather that the Engl is a tube preamp.  You could try placing either or both a common-mode r.f. filter or a differential-mode r.f. filter right at the preamp input.