Cembalet N Switch

[theseacowexists]

I just got a Cembalet N that I am working on restoring.  It was super noisy when I got it, so I recapped the board and now I'm waiting for new pluckers and dampers to arrive in the mail.  It's a bit less noisy now that it's been recapped, but the switch on the left cheek block is a mystery.  It seems like it should be a tone switch, but the up and down positions are still super noisy and crackly.  Only the middle position sounds pretty clean (the entire instrument seems to have a bit of hum to it).  I can't quite determine where it fits in the schematic either.  I am using the 100mV output and the Cembalet has the original swell pedal.  Anyone have any idea what that switch is for or why those two positions sound like crap?  Thanks!

[vanceinatlance]

That is, or should be, a tone switch. It doesn't make a whole lot of difference on my unit, but it is at least noticeable. Your switch may not be making good contact "corrosion?" in the other two positions. The electronics on mine seems to work great as an antenna and pick up and amplify any interference in the area. I added some makeshift shielding and grounding to help with that. Great instrument though, and strangely addictive to play. You are lucky to source the pluckers as I hear they are hit and miss on availability. I guess only one person makes these?? Congrats on your new instrument!

[theseacowexists]

I've taken a closer look at the schematic and there's definitely no switch on it.  The switch is wired directly to the pins of the swell pedal jack and nothing else. I'm hoping that I can access the switch and get some Deoxit in there and see if that clears things up.  I'll keep you updated.  You really hit the nail on the head about the electronics working great as an antenna for picking up interference!  My Pianet L does the same thing.  Maybe if I get them going at the same time I can pick up some Canadian radio from across Lake Ontario!  I've had an amplifier or two do it...

[theseacowexists]

Turns out that the cheek block can be removed by unscrewing it from the bottom of the instrument!  Attached are pictures of the small board I found hidden inside there.

From what I can gather, this board creates a high pass filter (switch down) and a low pass filter (switch up).  The center position is probably the unfiltered sound of the Cembalet.  My next step is to replace the components on the filter board and see if that cleans up the sound. 

Curiously, the back of the board identifies it as a "Pianet/Cembalet N Filter."  Has anyone else ever seen one of these installed on a Pianet?

[sean]

Eww.  Are those two big hairy unsheilded inductors on the left side?  Nice antenna.

Sean

[theseacowexists]

Yes they are!  Definitely gonna have line that whole cavity with copper tape...

[theseacowexists]

So I figured out why those tone switch positions sounded so bad.  On a whim, I tried plugging into the amp from the 300mV output.  According to Stefan, who sold me the new pluckers, the 100mV output is only for the CP amplifier, and the reason for the poor sound from the tone switch is because that output is meant to interact with the CP amplifier in a certain way.  Either way, I will stay away from that output from now on!  Now I have three nice and subtly different tone filters to choose from.  Still no luck on the vibrato though, but that's OK.