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  1. Matthew
  2. reface
  3. Tuesday, 23 March 2021
TLDR – I want to put the board from the reface CP & YC in a body with a master MIDI board and keybed and create a one off keyboard with a Rhodes style body. A switch that will select either CP/Off/YC and outputs that are linked so I can just plug the L & R into an amp and the switch will determine which sound I use. Is this possible?!

I stumbled across Paul J. Drongowski's webiste recently and was hoping to contact him for the advice, but I can't seem to find any contact info! Hopefully he or someone else that can provide help sees this!!

My background is mechanical engineering but my knowledge of electrical design is almost zero. Two of my favourite synths are my reface CP and my reface YC. But I always play them using a MIDI master keyboard. I also play the drums and have made my own snares, kits and pedals which got me thinking, I can make my own piano/organ with fender Rhodes style body. My plan is that I would take the internals of the CP, YC and MIDI master and put them in one case, but I would only ever use the CP sounds/YC sounds in isolation i.e. not wanting to mix them. In case I want to use the keyboard as a master still for other boards.

But this is where I need advice. I plan on using a 3 pos on off on switch, with one on providing power to the CP and master, and the other on position providing power to the YC and the master. Is this possible? Or am I talking out of my bottom as the saying goes? :p

For the MIDI I plan on having an output plate with midi out from the master, and a short cable that will go to a midi in. This then goes internally to a MIDI thru circuit with two outputs, one going to the CP and the other to the YC (with their annoying MIDI adapters!).

I’d like to also have only one set of outputs for sound and one input for expression. I.e. link the Headphone output from both CP & YC, link the L(Mono) from both and link the R from both. Again, is this possible? Is it as simply as using a split cable from each output internally and just mounting the single merged output to a face plate?

Feel free to chastise my lack of electrical knowledge and just point me in the direction of some literature to work through to do this on my own if you don’t want to/don’t have time to explain how to actually achieve this by the way.

Any help would be much appreciated!

Thanks and regards,
Matt
Responses (9)
Accepted Answer Pending Moderation
Hi Matt --

Just saw your post and I'm sorry that you had to wait for a response. Yeah, I am kind of hard to contact, but that's by design. :-)

I sometimes fantasize about putting the Reface YC into a chassis with a 49- or 61-key MIDI controller. It stays a fantasy because my construction skills are not up to snuff. Even simple boxes look rather crude when I get done with them. :D

Sounds like an interesting challenge, especially putting both CP and YC into the same mothership. Personally, I would shoot for having both instruments live (powered up) at the same time, sharing the same incoming MIDI stream. The MIDI THRU (or a MIDI splitter) idea sounds good.

I would probably go with separate 1/4 jacks for YC foot control and CP foot control. YC needs an expression pedal (continuous control) and CP needs a sustain pedal (foot switch).

Audio-wise, both YC and CP have auxiliary inputs. It's a shame that the front panel volume controls also control the AUX IN. Maybe if the CP was chained into the YC AUX IN, the YC can be silenced by setting all of the drawbars to zero? Otherwise, a small passive mixer should be enough to mix the 1/4 stereo outs into a single stereo MAIN OUT.

You definitely want to get the YC/CP service manual(s) before cutting iron, if that's your approach. The internal printed circuit boards are roughly the same and there are four of them: DMO (digital electronics), JKOF (jacks), PNO (front panel), PNOSW (front panel switch). In one fantasy, I would keep the YC and CP intact and bury them into the mothership, letting the MIDI controller control both. Ideally, I'd love to throw away the mini keyboards and somehow re-use the Yamaha front panels (the YC drawbars and the CP knobs/switches). That's the ultimate fantasy, but way beyond my construction skills.

Ripping everything apart is a major leap of faith (!) and it would be better to keep the YC and CP intact. It's just that I love to interact with the YC's front panel controls rather than a MIDI controller. That's just me, tho'. ;)

Hope this helps -- pj

Blog: http://sandsoftwaresound.net
  1. more than a month ago
  2. reface
  3. # 1
Accepted Answer Pending Moderation
The switch you're referring to exists and would work and comes in many forms. Slide, rocker, dial, etc.

Something like this:

https://www.te.com/usa-en/product-1571079-7.html

I'd probably go with a DP switch - there's DP versions similar to the above.

https://www.mouser.com/datasheet/2/140/RRA-1061891.pdf

... but either type will work. Just showing a round type to give variety. There are so many choices here that would work and do what you want as you've "designed" the idea.

The dual pole (DP) would have incoming power on the middle two switch pins then each side routes to each keyboard's power.

Kbd1PwrA --o o-- Kbd2PwrB
InputPwrA --o o-- InputPwrB
Kbd2PwrA --o o-- Kbd2PwrB

Where "o" are pins of the (DP) switch.

----------

If I was trying to do what you're doing - I'd keep them powered on all the time and connect the analog outputs to an A/B switch where either keyboard would be selected. You could make your own A/B with a switch of your choice (a DP rocker as above works fine for this). Or you could use the traditional push-button foot control.
  1. more than a month ago
  2. reface
  3. # 2
Accepted Answer Pending Moderation
Thanks both your responses!

I have been giving this a little more thought over the weekend coincidentally, and this is what I'm thinking, which also gives you a bit more info.

I am indeed planning on keeping the front panels and throwing away the mini keyboards. That way, they would be intact should I wish to resurrect them to original.

The reason I down want to power both is that I'd like to not have a mixer involved also. Theres the additional power source needed, more needed on the front face (as I wouldn't want the mixer externally but all internal) and also instead of just flicking from one sound to the other, I would have to turn one all the way down and the other all the way up. Having a reverse jack splitter cable would be ideal, but if both keyboards have power, I could blow the speakers with the combined voltage going through the outputs? Fair comment about expression/sustain.

This is why I'd like to have a rocker switch.

I think the Midi will always have power on from the main switch, and then I just use a rocker switch to provide power to the CP / YC. Its just the jack situation that I'm not sure on.

Thanks again! Seriously looking forward to getting this project underway in the summer!!
  1. more than a month ago
  2. reface
  3. # 3
Accepted Answer Pending Moderation
This is an example of the AB switch I'm suggesting (which isn't a mixer)

https://www.brightonion.co.uk/stereo-ab-input-switch/

Or a DIY version of the same thing. These are usually just passive switches with perhaps some termination.
  1. more than a month ago
  2. reface
  3. # 4
Accepted Answer Pending Moderation
Hi Matt --

It's all in the spirit of brainstorming, so it's all good! :D

Mixer-wise, I had a small passive mixer in mind. The Wikipedia page has the simplest possible design: a few jacks and two resistors. The resistors could be trim-pots to be set once to balance YC and CP, and then forgotten. I agree that it's best to avoid yet another thing to power.

As to producing a "hot" output and damaging speakers, that's not a worry with a passive mixer. The front panel volume pots would control the amount of signal going into the passive mixer. I worry more about speaker pops when the YC and CP are powered up and down. My YC pops like a bugger if I don't turn the volume down when powering up/down. There's also the delay while the YC or CP "boots" itself and is ready for action.

Compared to the physical construction, this is small potatoes. :D You're a better man than I to attempt this kind of construction!

In case other folks haven't seen these posts on my site, I included links below.

All the best -- pj

http://sandsoftwaresound.net/inside-reface-yc-and-cp/
http://sandsoftwaresound.net/reface-yc-dx-teardowns/
  1. more than a month ago
  2. reface
  3. # 5
Accepted Answer Pending Moderation
Thanks again Jason and Paul.

That AB switch from bright onions looks very promising!!

I also understand the appeal of having a passive mixer, but would I then have to switch between the CP and YC by using the front face volumes? If so, what happens if I accidentally try and play with both on full volume on the front face?

Having both powered up would seem a waste of energy if I’m mostly going to be sitting down to play some EP, or have any evening of organ playing. Ideally I’d like one power supply that I split using a rocker or toggle switch similar to what Jason sent.

In my head I would use the same switch to activate the AB switch suggested, but I realised I can’t do that, I’d need two toggles. One for power and one to determine which board will sound. Maybe then this is becoming too much and a passive mixer would be the better option. But I’d still like to only power one board at a time though. Hmmm lots to think about!!

I was also considering buying an EQ unit and using the circuit for that and put the pots on the new front face. Definitely something for further down the line though! After just moving house, I need to build a garage/workshop before I can actually undertake building the new case. Depending on timings, I may take apart everything over the next month or so, measure up and get an idea of the size of this thing.

I also have to consider the face the CP & YC are both powered by a 12V plug, and that they draw 6w of power (0.5A) when using the Yamaha psu, the Midi keyboard I will be using has a 9V 0.75A supply. To be honest I’m thinking of just have a kettle lead in to the new shell, and inside mount an RCD protected 2 gang and just having them plugged into that internally. As I’m going to be having a vintage EP overall look, should be space towards the rear to mount this. Saves me trying to design a circuit to distribute the right power to each unit safely.

Lots of food for thought!

Thanks for your help thus far both, really appreciate it.

Thanks,
Matt
  1. 4 weeks ago
  2. reface
  3. # 6
Accepted Answer Pending Moderation
I wouldn't want to wait for the selected Reface to power-on if I was using power ON/OFF to switch in and out the two keyboards. This is why I'd have them powered on at all times. If you're putting all of this in a Rhodes-style chassis then there's plenty of room for both Refaces' power supplies inside with a 2-3 slot power strip and a single power cable connection coming out.

The AB switch would switch in and out (instantly) the audio output of either keyboard.

Not all AB switches are created equal and I cannot vouch for any particular one. Some will be noisy while switching and some will not.

The push-to-toggle switch could be replaced with a rocker. They will have similar pinouts on the back end. That's if you don't want to create an AB from scratch and start with off-the-shelf and modify.
  1. 4 weeks ago
  2. reface
  3. # 7
Accepted Answer Pending Moderation
Hi Matt and Jason --

Just a few more thoughts.

The passive mixer would only apply to the stereo OUTs and maybe the headphone OUT. Playing both at once is just like playing both keyboards through a combo amp with two inputs (or some such equivalent amp). So, both voices would sound. Yep, there's always the chance to overdrive the amp connected to the mixed stereo OUT. That's just life, I guess.

I assume you're ditching the little built-in speakers? There isn't a clean way to mix the speaker signals and I wouldn't recommend it. A lot of audio amplifiers use the speaker resistance in the output path as part of the amplification circuit itself. Typical for digital amplifiers these days. In case anyone else is reading this, please don't connect the same speaker to two (or more) amplifiers, i.e., have two amps driving the same speaker simultaneously.

One could replace the two PA-130s with a single 12V PSU with a higher amp rating. Kinda like a PSU for a guitar pedalboard. Just curious, which MIDI controller are you using?

Interesting project! We get to live vicariously -- pj
  1. 4 weeks ago
  2. reface
  3. # 8
Accepted Answer Pending Moderation
Although a higher current P/S of the same voltage rating would be fine - given the amount of area inside the new chassis I would be "lazy" and just use the original supplies.

Probably one of those plastic chord "squeezers" (strain relief) for a pigtail coming out - maybe even a tie strap on the inside to keep it mechanically fixed. And some "vacuum cleaner hooks" to wrap the power cable around for transport. Ideally the type of plug with a "notch" that can push into the cable to keep it from unraveling - again like the vacuum cleaner.

Strain relief (one example) ...
https://www.newark.com/productimages/standard/en_US/4308645.jpg

I guess what's easier depends on your perspective. Functionally they're equivalent.
  1. 4 weeks ago
  2. reface
  3. # 9
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