Author Topic: adding a second, direct output to a MKI Rhodes  (Read 424 times)

Offline ummagumma

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adding a second, direct output to a MKI Rhodes
« on: February 08, 2020, 03:11:44 PM »

 I was looking at the wiring in my MKI, and the signal going to the tone/vol controls is just fed via an RCA jack + cable from the back of the harp

 I hear a lot of people advising to bypass of the tone/vol controls, for recording

 what I propose to do is just add an RCA splitter cable back there. it would:

 1. retain the existing vol/tone control output
 2. add a second 1/4" output that feeds from the other RCA, which would be DI

 I would need to drill a 2nd output jack on the front of the panel though. there is lots of room there, to the left of the existing 1/4"

 any reason not to do this? not keen on drilling holes in vintage stuff, but it would be pretty unobtrusive, and very useful.

 I could even use both outputs to feed stereo/multiple signal paths


Offline sean

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Re: adding a second, direct output to a MKI Rhodes
« Reply #1 on: February 08, 2020, 08:37:56 PM »

Don't do it.  It will not lead to happiness. 

You will regret drilling into a Mark I namerail.  (On Mark II pianos, you can make a replacement contol plate.)

There is little reason to bypass the namerail controls.  If you have a modern preamp or modern guitar amp, you won't need to.

If you have an old tube amp that suffers when the input is shunted by the Rhodes piano's 10KΩ volume pot, then it is really easy to disconnect the name rail controls, and snake an RCA cable underneath the harp cover.

It is also worth spending an hour doing A/B tests with your amp to prove to yourself that direct-from-the-harp will not change your life.  Or maybe, proving to yourself that it does change your life, and it is worth modifying your 50-year-old Rhodes piano.

Sean

Offline ummagumma

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Re: adding a second, direct output to a MKI Rhodes
« Reply #2 on: February 09, 2020, 11:41:59 AM »

 those are good points, thanks!

 I wonder if I could just snake the RCA splitter 2nd output out somewhere unobtrusive, and leave it?

 the harp cover sits flat ( well, on an angle but in contact all around ) so it would pinch the RCA cable

 I have a moog grandmother and a bunch of other stuff on top of the cover, so there is a lot of weight there

Offline bourniplus

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Re: adding a second, direct output to a MKI Rhodes
« Reply #3 on: February 09, 2020, 03:35:23 PM »
+1 to sean's post.

I sometimes think of splitting the pickup rail of my Mk1 (bass/treble) so I can send the bottom two octaves to be amplified separately from the rest, for when I want to play left hand bass. The main thing that keeps me from doing it is having to drill in the nameplate.
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Offline 4kinga

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Re: adding a second, direct output to a MKI Rhodes
« Reply #4 on: February 10, 2020, 07:10:53 AM »
There was talk a few years(?) back about using a push-pull potentiometer to by-pass the passive panel components.  I don't recall if anyone ever completed that.
https://www.ebay.com/itm/POTENTIOMETER-PUSH-PULL-SWITCH-POT-GUITAR-10K-LIN-SPLIT-SHAFT-LINEAR-V164L4-/271184505955 possibly?

Offline Coyote Circle Studio

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Re: adding a second, direct output to a MKI Rhodes
« Reply #5 on: February 10, 2020, 02:11:29 PM »
It might be a tad bit convoluted, but you could wire up a TRS jack that replaces the standard TS jack.  That way no modifications like drilling holes.  Split the signal send from the back of the harp, and send one signal as normal to the preamp and the other to the TRS jack ring terminal.  Wire the jack with ground to sleeve, preamp out to tip and direct from harp to ring. 

Then make yourself a few custom cables.  Make one that has a TRS plug on one end and TS on the other.  Only wire the tip and sleeve.  Plug the TRS end into the output jack of the piano and it will not send the direct output anywhere, only the regular preamp out to an amp.  If you use a regular TS instrument cable, it will short the signal from the harp to ground, you don't want that.  You need that ring connection on the output jack side to float with no connection out or to ground.

For recording, get a TRS Y-cable, send the tip (preamp out) to your amplifier, and the ring (direct from harp) to a di box.

It does require making at least one custom cable, and a few minutes of soldering, but it would be completely reversible, and not screw things up by drilling extra holes.
« Last Edit: February 10, 2020, 02:16:03 PM by Coyote Circle Studio »

Offline sean

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Re: adding a second, direct output to a MKI Rhodes
« Reply #6 on: February 10, 2020, 04:14:31 PM »

The Coyote Circle Studio method would not remove the bass boost cap and the 10KΩ volume pot from the circuit - and that was the whole point of starting this mess.

Having a DPDT switch on the volume pot would enable a true bypass of the bass boost and volume, but the pot in the ebay listing is linear taper, not audio taper.

Sean

Offline Coyote Circle Studio

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Re: adding a second, direct output to a MKI Rhodes
« Reply #7 on: February 11, 2020, 10:52:22 PM »
Please correct me if I am wrong, I have a different model (1977 88 suitcase) and don't want to assume, but I thought the rca direct off the harp was before any of the tone (or bass boost) or volume  controls. 

If that is correct, then if you were to split the signal at the rca direct out of the harp, you would have one signal going as normal to the tone or volume controls then going to the tip terminal, and a second direct signal straight off the harp going to the ring terminal.  That way you could use the TRS y-cable (insert cable) and have access to the normal signal path (tip) and/or the direct unaffected signal path (ring) as you choose.

You would bypass the tone/bass boost/volume by only sending the ring terminal signal to whatever amplification/recording device.

I may have confused things by previously saying "preamp in" and "preamp out" instead of "tone/volume in and out" as I was looking at my 88 suitcase with facerail preamp.  I apologize for that.  Nonetheless, it would be the same idea even with passive tone or volume controls.

Adding that push/pull pot still leaves a component in the audio path, allowing some amount of insertion loss.  My method takes a direct tap off the harp, no switches or other components in the signal path, which as I understand, was the o.p.'s original goal for recording.  Less potential for signal degradation.
« Last Edit: February 11, 2020, 11:05:29 PM by Coyote Circle Studio »

Offline ummagumma

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Re: adding a second, direct output to a MKI Rhodes
« Reply #8 on: March 14, 2020, 01:20:12 AM »
thanks everyone!

I will do some AB tests when I have time, with the cover off & see if it makes any difference going direct via RCA vs the front 1/4" jack

that is a good point about a preamp/amp negating any benefit of the DI