Mono/Poly variations

Discussions about anything analog, digital, MIDI, synth technology, techniques, theories and more.
Post Reply
User avatar
Junior Member
Junior Member
Posts: 116
Joined: Mon Mar 05, 2007 10:17 pm
Gear: B3, CP-30, DX7, Casiotone MT-210, Axxe 1, EPS-1, Promars, MC-202, TR-606
Location: Mechanicsburg, Pennsylvania, USA

Mono/Poly variations

Post by Synthazaiser » Fri Jan 11, 2008 2:06 am

I just learned that there are two different versions of the mono/poly. It looks like the later version had 33kohm resistor between the VCO out and SSM, where as the earlier version has a 47kohm resistor. How could I tell, without taking apart the synth, if I have a new or old version? Does anyone know at what point in the serial numbers this change was made? Also, could the resistors in an old version be changed to the new value and safely work? My Mono/Poly is serial number 371801.
Currently have: Baby Grand Piano, B3, CP-30, DX7, Casiotone MT-210, Axxe 1, EPS-1, Promars, MC-202, TR-606
Used to have: POLY-800, TR-505, Techstar TS-306, DX7, ESI-32, Juno-106, DX27, Synthcart, JX-3P, ESQ-M, Mono/Poly, MS2000BR, VX90

User avatar
Active Member
Active Member
Posts: 270
Joined: Sun Feb 12, 2006 2:37 am
Gear: Mono/Poly, Polysix, Crumar Performer, Juno106, Ion, CS01, K Station, DX27,77' Rhodes 88 mk1
Location: SF bay

Post by brian.only » Fri Jan 11, 2008 6:22 am

Interesting, I had no idea- any engineering types around know what the difference would be between the two hypothetically?
sell me your KS5!

Active Member
Active Member
Posts: 335
Joined: Thu Oct 05, 2006 4:08 pm

Post by steveman » Fri Jan 11, 2008 12:06 pm

According to this site: earlier models had a digital noise source, while later models used an analogue noise source.

Not sure what difference the resistor would make - unless you understand this: ... rcuits.pdf

Can't see it's worth worrying about.

User avatar
Junior Member
Junior Member
Posts: 174
Joined: Mon May 22, 2006 6:56 am

Post by Dirk » Fri Jan 11, 2008 6:43 pm

Here are the differences of the two versions. ... =mp_07.gif ... =mp_08.gif

Main difference is the voltage divider that is made up of R1 and R3. The new version allowes twice the amount of voltage to the filter. It's an eazy fix for any person that can solder. You can ofcause make the voltage divider so that it even allowes more voltage into the filter for serious filter overdrive. Just make R3 bigger, 1k-5K should give you extreme filter distortion (but try a small potmeter here). And you can alway's turn the VCO level's down with the mixer. I haven't tried to change R3, so it's not tested.

The monopoly of my friend has serie number 375233 and is the new version.
All Animals Are Created Equal But Some Are More Equal Than Others.

User avatar
Synth Explorer
Synth Explorer
Posts: 2556
Joined: Sun Jul 09, 2006 12:04 am
Gear: Check my sig
Location: Scotland, United Kingdom

Post by OriginalJambo » Fri Jan 11, 2008 10:09 pm

Dirk wrote:The monopoly of my friend has serie number 375233 and is the new version.
Thanks for that.

As my serial number is 376697, I think it's most likely the of newer production run.

Post Reply