Yamaha CP-70

[Regi Hedahl]

I acquired this Yamaha CP-70.  It was badly out of tune so I tuned it.  Here's a video of it with me playing some Chopin.  It's a different sound but pleasant in it's own way.

https://youtu.be/X63IxMZ81ng

The damper pedal is squeaking and I can't figure out how to slide out the action.  I removed 4 screws that hold the stretcher and 4 other screw for the keyslip and that is far as I got.  What else do I need to do?

Regi Hedahl

[David Boyce]

Thank you for uploading that, Regi. It's always a pleasure to hear your
playing! There is a certain charm in the sound of that instrument,
isn't there.

Best regards,

David B.

[Joseph Garrett]

Regi,
I have a service manual for it. I'll peruse it and get back to you.
Best,
Joe

-----Original Message-----
From: Regi Hedahl
Sent: Mar 21, 2017 4:38 PM
To: pianotech
Subject: [pianotech] Yamaha CP-70

I acquired this Yamaha CP-70.  It was badly out of tune so I tuned it.  Here's a video of it with me playing some Chopin.  It's a different sound but pleasant in it's own way.

https://youtu.be/X63IxMZ81ng

The damper pedal is squeaking and I can't figure out how to slide out the action.  I removed 4 screws that hold the stretcher and 4 other screw for the keyslip and that is far as I got.  What else do I need to do?

Regi Hedahl

Captain of the Tool Police
Squares R I
gpianoworks.com

[Joseph Garrett]

Regi,
It appears, from the minimally helpful diagrams, that the whole pedal unit is scewed to the underside of the case. It has a pitman rod that has a rubber "t" grommet that I suspect has died and now has the pitman rod pin rubbing agains the damper tray. The "t" grommet is the same as on uprights trap rods. Should be all accessible from underneath. (Hopefully!??)

[Regi Hedahl]

Joe,

Thanks for looking this up. I had a "duh" moment and realized all that I had to do was separate the top part of the piano which consists of the harp and string assembly out of the way. It rotates on a hinge and makes the action accessible from the top. The rubber grommets were still fine and pitman rod was made out of nylon. I lubed the areas that could cause noise with Protek MPL-1 and it's all quiet.

Regi

[David Nereson]

Hi, I have a set of never-used bass strings for a CP-70, still in the wrapper from Yamaha.  (Used to work on them.)   Admittedly they're quite old (late 1980's) but if you want them you can have them for merely reimbursing me the shipping cost.  --David Nereson, RPT  da8...@gmail.com

[Joseph Garrett]

Regi,
That's true, but if you need to go deeper you have to attack it from underneath. There is a pass through "flange" that can be removed from the bottom. Have fun. BTW, I have Escaine for the hammers on dem things.<G>
Best,
Joe

Captain of the Tool Police
Squares R I
gpianoworks.com

[John Formsma]

Glad you posted the YouTube video. I've read much over the years about the CP-70, but have yet to hear one. The sound is interesting, and pleasing in some aspects.

John Formsma, RPT

New Albany, MS

[Regi Hedahl]

Joe,

Mine doesn't appear to have a pass through under the keyboard. The only pass through is under the tail end that gives access to the electronic pickups under the plate.

What would be neat to do with this thing is install a QRS midi optical sensor strip and play this thing through a virtual piano.

Regi

On Wednesday, March 22, 2017 at 7:29:36 PM UTC-5, Joseph Garrett wrote:
> Regi,

[Joseph Garrett]

AND, it's a REAL piano action! I like them. I've rebuilt two of them. The CP-70B is the good one, because of it's midi interface. With that it becomes the whole enchilada! <G> Hook them up to other midi devices, etc.
I found that I had to make some special tools to regulate the suckers though, since you can't slide the action in/out for that process. That's the only down side I've seen with them. The CP-80 is a full 88. I have yet to run into one of those.
Best,
Joe

-----Original Message-----
From: John Formsma
Sent: Mar 22, 2017 6:05 PM
To: "pian...@googlegroups.com"
Subject: Re: [pianotech] Yamaha CP-70

[Joseph Garrett]

Regi,
It has to have a "pass through", otherwise how does the pedal actuate the dampers. Check closer.
Joe

Captain of the Tool Police
Squares R I
gpianoworks.com

-----Original Message-----
>From: Regi Hedahl <piano...@gmail.com>

>Sent: Mar 22, 2017 6:26 PM
>To: pianotech <pian...@googlegroups.com>
>Subject: Re: [pianotech] Yamaha CP-70
>

[Regi Hedahl]

Joe,

I get it now. The pass through was the first thing I had messed with.

Regarding the CP-70b, what kind of key contact switching does it use? Is is the pressure type or optical? And where is it placed? Under the front of the keys? Does is sense velocity?

Regi

[Joseph Garrett]

Your questions about the CP-70B? No clue. You'll have to ask Yamama or a tech familiar with the electronic aspects of the beast. I'm an electronic dufus!<G> (Except on stuff that has vacuum tubes and the like.<G>)

Best,
Joe


Captain of the Tool Police
Squares R I
gpianoworks.com

-----Original Message-----
>From: Regi Hedahl <piano...@gmail.com>
>Sent: Mar 22, 2017 8:05 PM
>To: pianotech <pian...@googlegroups.com>
>Subject: Re: [pianotech] Yamaha CP-70
>

[Regi Hedahl]

No problem, maybe there is someone on this list who is familiar with this aspect of the CP-70b. If it's the pressure sensitive system, I'm just curious on how it was done to not alter the touch.

Interestingly, someone has already done what I had mentioned in a previous post. They retrofitted the QRS PNOscan midi optical sensors into this instrument. The advantage of this sensor design is it doesn't alter the touch.

https://www.retrolinear.com/new-stuff/dso-round-2!-midi-cp70-more!.aspx

Regi

[Joseph Garrett]

Regi,
I suspect it was incorporated into the main electronic circuitry. Perhaps the person that offered the set of bass strings would know.
BTW, those things had breaking string problems in two situations: 1. If the action was way out of regulation. 2. Some had some bad scaling. I have rescaled one that had that problem.

Best,
Joe


Captain of the Tool Police
Squares R I
gpianoworks.com

-----Original Message-----
>From: Regi Hedahl <piano...@gmail.com>
>Sent: Mar 22, 2017 9:21 PM
>To: pianotech <pian...@googlegroups.com>
>Subject: Re: [pianotech] Yamaha CP-70
>

[Terry Farrell]

Oh wow, thanks for the additional picture from above with the action opened. Looking at the other photos I was trying to figure out what the heck I was looking at - kinda looked like there was a mirror above the piano. Now I see that it opens and splits the action/plate/etc. in two. Amazing! I tuned one of these many years ago and sure found it interesting. The guy didn’t have an amp, so I couldn’t hear what it sounded like. I enjoyed your sound clip and thought it sounded much better than I had imagined with the super-short strings and all. I’m surprised these things didn’t find wider acceptance. An engineering marvel IMHO.

Terry Farrell

> <IMGP0734.JPG>

[Joseph Garrett]

Terry,
There are tons of those out there. Most are just languishing in some dusty corner/closet. Once the Digitals got better, it was a no-brainer, (or no-brawner), because it took two people to move one, even in the two parts. They weigh a lot because there a real plate in there! I've worked on a bunch, back in that day. Easy to tune, but a bear to fix sometimes.

Best,
Joe


Captain of the Tool Police
Squares R I
gpianoworks.com


-----Original Message-----
>From: Terry Farrell <farrellpi...@gmail.com>
>Sent: Mar 23, 2017 5:11 AM
>To: pian...@googlegroups.com
>Subject: Re: [pianotech] Yamaha CP-70
>

[Sam McUmber]

I have one of these at home, they're beautiful instruments. There are a number of indie and popular artists that still use them for the characteristic sound.

Sebastian Tellier:

https://www.youtube.com/watch?v=crblDrrcunQ

Keane

https://www.youtube.com/watch?v=Zx4Hjq6KwO0

Sigur Ros (CP-70 starts right at 1:00)

https://www.youtube.com/watch?v=UeuvegBZFuM

[lim hock seng]

Regi,

<Regarding the CP-70b, what kind of key contact switching does it use? Is is the pressure type or optical? And where is it placed? Under the front of the keys? Does is sense velocity?>

None of these above if i remember correctly. It is in my opinion an analog electric grand piano. I think the sound passes through transducer wires from the bridge to the amplifier/equaliser and to the speakers.
I serviced one of these in the early 90s.

Best regards,
Lim

[Rick Ucci]

There's like a hybrid piano guitar sort of. Pick ups under the strings plug it into an amp that's pretty much it. Tuning the base was always the real problem but I got used to it.

Used to do a bunch of them on a daily basis back in the 80s.

Rick Ucci

Uccipiano.com

[Regi Hedahl]

I'm talking about the midi feature on the CP-70b. There would have to be some type of key contact to convert analog to digital. The digital in this case would be the midi signal. How is that signal produced? Is it a pressure key contact or some other type?

Regi

[Joseph Garrett]

Rick
Not so. The pickups are Transducers, not electromagnetic. On the CP-70B the midi interface is in the existing electronic circuitry somehow. I can't tell you specifically how it was done though.<G> (I don't have the circuit schematic.)
Best,
Joe

-----Original Message-----
From: Rick Ucci
Sent: Mar 25, 2017 5:25 AM
To: pian...@googlegroups.com

Subject: Re: [pianotech] Re: Yamaha CP-70

There's like a hybrid piano guitar sort of. Pick ups under the strings plug it into an amp that's pretty much it. Tuning the base was always the real problem but I got used to it.

Used to do a bunch of them on a daily basis back in the 80s.

Rick Ucci

Uccipiano.com

On Mar 25, 2017, at 2:32 AM, lim hock seng <limh...@gmail.com> wrote:

Regi,

<Regarding the CP-70b, what kind of key contact switching does it use? Is is the pressure type or optical? And where is it placed? Under the front of the keys? Does is sense velocity?>
None of these above if i remember correctly. It is in my opinion an analog electric grand piano. I think the sound passes through transducer wires from the bridge to the amplifier/equaliser and to the speakers.
I serviced one of these in the early 90s.

Best regards,
Lim

On Mar 23, 2017 11:50 PM, "Sam McUmber" <smcu...@gmail.com> wrote:

I have one of these at home, they're beautiful instruments. There are a number of indie and popular artists that still use them for the characteristic sound.

Sebastian Tellier:

https://www.youtube.com/watch?v=crblDrrcunQ

Keane

https://www.youtube.com/watch?v=Zx4Hjq6KwO0

Sigur Ros (CP-70 starts right at 1:00)

https://www.youtube.com/watch?v=UeuvegBZFuM

[Joseph Garrett]

As I posted, it's unknown w/o a circuit diagram. Find that and you'll have the answer. I can say that it is NOT in the key assembly. That remained the same.
Joe

Captain of the Tool Police
Squares R I
gpianoworks.com

-----Original Message-----
>From: Regi Hedahl <piano...@gmail.com>

>Sent: Mar 25, 2017 6:06 AM
>To: pianotech <pian...@googlegroups.com>
>Subject: Re: [pianotech] Re: Yamaha CP-70
>

>I'm talking about the midi feature on the CP-70b. There would have to be some type of key contact to convert analog to digital. The digital in this case would be the midi signal. How is that signal produced? Is it a pressure key contact or some other type?
>
>Regi
>
>

[Rick Ucci]

Not familiar with that one. Could be a laser light type like on the DK

Rick Ucci
Uccipiano.com

[Terry Farrell]

It is a real grand piano with a real grand piano action. The belly has a strung cast-iron plate similar to most any grand piano, although the string scale (plain wire in the tenor and treble, and wound strings in the bass) is exceptionally short. However, the belly does not have a soundboard - rather it has electronic pick-ups, if I recall correctly, on or very near where one would expect a bridge to be. The pick-ups a appear similar to an electric guitar pick-up, and function much the same.

So the piano works just like a real grand piano in that one hits the key, the key drive upward a hammer, the hammer hits the string and the string vibrates. The only fundamental difference is in how the string vibration is made to move a sufficient volume of air so that humans can hear it - a real piano has a soundboard that is set in motion by the vibrating strings, whereas on the CP-70, electronic pick-ups pick up the string vibrations and those in turn a fed to an electronic amplifier which sets in motion speakers.

Does that make sense?

Very cool piano IMHO.

Terry Farrell

[Joseph Garrett]

Terry,
Yes, they are way cool. No they do not have electro-magnetic pickups, (as in electric guitars), but rather transducers such as are used on acoustic guitars and acoustic stringed instruments. All the rest? Yup. Real grand action and such.
 The hammers are not made of felt though. they have a synthetic rubber on the tips and then covered with Ecsaine. New cover material is needed from time to time, just as regular hammers require surfacing, etc. Voicing is NOT part of the this system.<G>
Because the action does not slide out like a regular grand action, special regulating tools, (gauges, etc.), need to be employed. The general specs are not "standard".
 BTW, even with toting them around in Ford Econolines and such, they stay in tune very well. Only down side is they only have one pedal,  the sustain.
I've always wanted one, but they are hard to find. When you do find one, generally, the owner will not part with it...EVER!<G>
Best,
Joe

-----Original Message-----
From: Terry Farrell
Sent: Mar 25, 2017 10:41 AM
To: pian...@googlegroups.com

[Terry Farrell]

Thanks for the input Joe. I know very little about guitar pick-ups. What is the difference between an electro-magnetic pickup and a transducer pick-up?

Terry Farrell

[Larry Fisher RPT]

UH, let me see if I can clear a few things up here.

A transducer converts physical movement into electrical energy, and vice versa.  A guitar pickup or piano pickup such as the Barcus Berry simply attaches to the soundboard or a piano, violin body, guitar body and senses the vibrations of whatever it's attached to and converts it to electrical energy to be amplified.  Vice versa, the MSR transducer was attached to a soundboard of a piano and actually used the soundboard of the piano as the amplifier so you could hear the orchestra and somebody singing through the soundboard of the piano.  The one I saw was mounted on a 7 foot M&H I think.

CP70's, Helpenstihl and a host of others perhaps are electromagnetic pickups similar to the ones found on electric guitars.  An electromagnetic field is interrupted or "disturbed" by the vibrating metal strings (nylon has no effect) and the resulting changes in the magnetic flux are sensed by the electronics and then amplified to a speaker.

MIDI retrofits are typically installed under the keys, (I believe Disklaviers had/has them on the hammer shank) and a shutter interrupts a laser beam.  The last time I gave a rip about this sort of thing, I found the shutter to be two tiered.  The first interruption of the laser beam indicated keydown, the second being a wisp of a moment later indicated velocity.  Multiplexing determined which key, which octave and at what velocity.  The TFT systems relied on the amount of "shock" or "level of charge" created when you bend a crystal.  The older sensors used small bent gold wires that slid across contacts on a circuit board.  As you'd press a key, the underside of a key would press on a bend in a wire pushing the end of that wire across the contacts on a circuit board.  These were the days before multiplexing and so there was a wire for every note.  Later they developed a spring loaded plastic actuator that accomplished about the same thing only with the shutter concept described above contained inside a small black box.  Then again, maybe they originally had micro switches in each black box and developed the interrupted beam stuff later.

Your results may vary, contents may have settled during shipping, not responsible for loss or injury, use at your own risk, I don't care if you don't understand and I may be wrong. 

Lar

[Paul McCloud]

Uh, Larry.. you forgot "No serviceable parts inside. Call a qualified technician". Lol!

QRS hired Dave Starkey, who developed an original midi keyboard strip installed under the keys. It used small plastic arms that contacted the bottom of the keys. The arms were part of those small boxes you mentioned, all mounted on a common metal rod and attached to circuit boards that the little boxes were soldered to. The company he developed them for was Gulbransen. I the system was originally just a midi controller. Gulbransen also sold a synth box which mounted under the keybed for different sounds, amplified though a powered speaker mounted under the piano. It was called Crystal. Here's one for sale on Ebay:

http://www.ebay.com/itm/Gulbransen-crystal-combo-I-/262889435322?

At the Piano Exchange, where I used to work, we installed a lot of these systems. They also developed a Digital Hymnal, which I see that QRS now has for sale. I believe QRS purchased the technology from Gulbransen.

Now working for QRS, Dave has developed a laser system which has no actuators. I don't believe they sense the hammer shank, but maybe they now have that. You may see him at the QRS booth at NAMM, showing the latest technologies he's developed. The guy is a friggin genius, and very personable. He lives about 5 miles from me.
Paul McCloud
San Diego

----- Original Message -----
From: "Larry Fisher RPT" <larry_...@pdxtuner.com>
To: "pianotech" <pian...@googlegroups.com>
Sent: Sunday, March 26, 2017 8:09:03 AM
Subject: Re: [pianotech] Re: Yamaha CP-70

[Joseph Garrett]

Lar,
I'm fairly certain that the tail termination on the CP-70/80's is a transducer. The rest of what you say is up for grabs.<G>
Best,
Joe

-----Original Message-----
From: Larry Fisher RPT
Sent: Mar 26, 2017 8:09 AM
To: pianotech
Subject: Re: [pianotech] Re: Yamaha CP-70

UH, let me see if I can clear a few things up here.

A transducer converts physical movement into electrical energy, and vice versa.  A guitar pickup or piano pickup such as the Barcus Berry simply attaches to the soundboard or a piano, violin body, guitar body and senses the vibrations of whatever it's attached to and converts it to electrical energy to be amplified.  Vice versa, the MSR transducer was attached to a soundboard of a piano and actually used the soundboard of the piano as the amplifier so you could hear the orchestra and somebody singing through the soundboard of the piano.  The one I saw was mounted on a 7 foot M&H I think.

CP70's, Helpenstihl and a host of others perhaps are electromagnetic pickups similar to the ones found on electric guitars.  An electromagnetic field is interrupted or "disturbed" by the vibrating metal strings (nylon has no effect) and the resulting changes in the magnetic flux are sensed by the electronics and then amplified to a speaker.

MIDI retrofits are typically installed under the keys, (I believe Disklaviers had/has them on the hammer shank) and a shutter interrupts a laser beam.  The last time I gave a rip about this sort of thing, I found the shutter to be two tiered.  The first interruption of the laser beam indicated keydown, the second being a wisp of a moment later indicated velocity.  Multiplexing determined which key, which octave and at what velocity.  The TFT systems relied on the amount of "shock" or "level of charge" created when you bend a crystal.  The older sensors used small bent gold wires that slid across contacts on a circuit board.  As you'd press a key, the underside of a key would press on a bend in a wire pushing the end of that wire across the contacts on a circuit board.  These were the days before multiplexing and so there was a wire for every note.  Later they developed a spring loaded plastic actuator that accomplished about the same thing only with the shutter concept described above contained inside a small black box.  Then again, maybe they originally had micro switches in each black box and developed the interrupted beam stuff later.

Your results may vary, contents may have settled during shipping, not responsible for loss or injury, use at your own risk, I don't care if you don't understand and I may be wrong. 

Lar


On Saturday, March 25, 2017 at 6:06:18 AM UTC-7, Regi Hedahl wrote:

I'm talking about the midi feature on the CP-70b.  There would have to be some type of key contact to convert analog to digital.  The digital in this case would be the midi signal.  How is that signal produced?  Is it a pressure key contact or some other type?

Regi

[Mark Schecter]

It's  been a while, but here's the thing about Yamaha Disklavier: they have a light-and-shutter sensor on both the key and the hammer shank. This enables the system to self-calibrate and thereby compensate for minor irregularities in the regulation. The self-calibration routine sends a known voltage to the key activation solenoid, and measures the hammer speed that results.  By doing this at several different activation voltages (i.e. key speeds) for each key, and storing the results, a table is built up that contains a calculated compensation factor to be applied whenever that key is called to play at a given dynamic level. If the regulation of key x is inefficient, i.e. hammer speed measures low for a given voltage,  extra voltage is sent whenever that note is activated, resulting in the required hammer speed. Of course, this cannot compensate for uneven hammer voicing. 

Mark Schecter, RPT

 | |   | | |   | |   | | |   | |   | | |_

[Joseph Garrett]

Mark,
Please tell me what that has to do with the CP-70/80's!???! Same company, but what else?
Joe

-----Original Message-----
From: Mark Schecter
Sent: Mar 26, 2017 1:38 PM
To: pian...@googlegroups.com
Subject: Re: [pianotech] Re: Yamaha CP-70

[Mark Schecter]

Somebody, Lar I think, was speculating about how the disklavier sensed key motion, so I answered that. I don't think that system is readily adaptable to converting a CP-70 to a MIDI controller. It does send and receive MIDI commands, but that is just a small subset of what it does, so it's not a practical approach to MIDIfying anything that doesn't already include it. 

Mark Schecter

 | |   | | |   | |   | | |   | |   | | |_

On Mar 26, 2017, at 1:44 PM, Joseph Garrett <joega...@earthlink.net> wrote:

company

[Joseph Garrett]

Ah yes. Lar did get a bit far afield. But, we were actually talking about the CP-70B's midi capability and Lar was one that was trying to figure out how it was accomplished. As I said the midi came from the onboard electronics as far as I know. How that was accomplished I do not know. Midi was in it's infancy when the CP-70's and 80's were made. They put the midi capability in the last version of the it with the CP-70B. What the heck the "B" stood for I have no clue either. Perhaps someone has an inside source to Yamama that might know. I don't have the manual for those later ones.
Best,
Joe

-----Original Message-----
From: Mark Schecter
Sent: Mar 26, 2017 4:17 PM
To: pian...@googlegroups.com
Subject: Re: [pianotech] Re: Yamaha CP-70

[David Glover]

Hi all, 

I own three CP pianos, and just thought I'd clear a few things up (I know this thread's pretty old but it turned up in a search of mine...)

• There were three basic models in the CP- series: the most common was the CP-70 73-note grand which you can see in the original post; then there's the CP-80 88-note grand; finally there's the CP-60, a 76-note upright version with a rather cool fold down keyboard (Google some images).
  
• The "B" stands for "balanced". This was the second iteration, with transformer-balanced audio outputs.
  
• The MIDI versions (which they did for all three versions) have an M suffix
  
• The pickups in the CP series are individual piezos embedded in the bridge.
  

As to how the MIDI sensors work. I don't know exactly, but they're mounted under the keybed on my CP-60M. I'd assumed they were optical, but that's really a guess.

Hope that's helpful!

David

[Joseph Garrett]

David,

Thanks for the clarifications. I've worked a few. Have not seen the CP-60. Sounds kind of cool, actually. One thing still puzzles me. The CP-70B's that I worked on did have midi, but no "M" designation any where I could see. Of course, the memory banks are getting a bit faulty of late.<G>

Joe

[David Glover]

Hi Joe,

I wonder whether the ones you worked on had it added after? I know there used to be a couple of different aftermarket options.

After I posted, I dug out the service manual I have for the CPs and found there were also ‘D’ models, which seemed to add an equaliser.

Cheers,

David

[Joseph Garrett]

Hmm? Nothing like that in my manual that I recall. Now, I have to go and read the darn thing again!<G>