I bought this ugly beast back in 1995 and it was my third analogue synth ever. I hesitated to buy a machine without cv/gate control but thought that using the keys for once could be nice and despite all the mockery this has caused me I've kept it and I'm not ashamed to say I love this machine.

I bought it from a guy I didn't know then but whom I know consider a friend. I think he thought he made a really good deal getting rid of this DCO-mono-oneoscillator-organ-wannabe but with the original manual in great condition and a homebuilt case to go with the synth I though 800 SEK (circa 90 EUR) was well spent money.

The Monos main talent is droneing basses, almost Taurus-like sometimes but it can also produce some weird noises and effects. For example, the airplane simulator described in the manual is really convincing... (yes, I mean it!)

Unfortunately the Mono is very italian in many ways. It has cheesy controls (rocker switches and sliders that feels cheap), the design really sucks (wedge-shaped in brown metal casing with tiny little legs to tilt it even more), it uses DCO (though I promise it can sound warm anyway) and everyone says it's impossible to midify. 

I and a friend who is more on speaking terms with the soldering iron and electronics were discussing this and with tonnes of help from him and the splendid MTC64 from Doepfer my Mono now has midi control. Since I'm totally against non-reversable modifications (even on a poor SIEL) I used the volume pedal input (already a 5din-socket) for the midi in and double IC-sockets for the oscillator in the Mono.

First, with a lot of extra wiring, an extra PSU, we managed to squeeze three octaves + a C out of the Mono, the same as the layout of the keys. It included an extra board with switches since the Mono has a scanned keyboard like an organ. In addition to this I planned a midicontrol for the octave switch. But while looking into this, comparing the schematics with those of the SIEL Cruise (isn't the net and friends wonderful?) I ran into the possibility of more...

The schematics showed obvious signs of an extra octave below the visible keyboard. I tested and it worked! A just yesterday when taking the Mono apart for the phot session I double checked another idea and found out that it had another octave below the already mentioned one! I can tell you this much, the basses down there are LOOOOOW!

Servicing the Mono is easy since it has hinges on the lid and a similar solution for the keyboard, so with all propped up everthing is easily accessible.

The main feature that I always mention when people wonder why I've kept this beast is the filter. It has three switches (on/off) for lowpass, bandpass and highpass and these can be combined into notch, all etc. The resonance is vicious and probably only surpassed by the one in the Octave Cat SRM.

SIEL is a short form for Societa' Industrie Elettroniche by the way. And yes, the Mono is the little brother of the Cruise but I've never understood the point in having a ugly polyphonic space-waster when I can have a Mono! =)

SIEL Mono specifications;
 

Keyboard	37 keys, 3 octaves
Oscillator	DCO, semi-preset, switchable between ramp, filtered sawtooth, narrow square, broad square and pulsewidth.
Filter	24 (?) dB/oct, self-oscillating
Envelope	ADSR (can control both VCA and VCF or just VCA)
LFO	sine, with simple speed and depth control
External control option	MIDI (in, thru hidden inside) by help from Doepfer MTC64 and designs of Ricard Wanderlöf
Connections	line output, phones output, volume pedal in (converted into midi in)
Housing	plastic & steel
Dimensions	768 x 343 x 148 mm
Weight	approx. 9 kg
Released	1980
Quantity produced	approx. 5000 (fair guess, based upon availability)
Pros	Unique sound, cheap, sturdy construction.
Cons	No control interface except keys, ugly as hell, easy to get irritated on the presets.
Price? (bargain, fair, horrible)	$100, 250, 400

Happy browsing and don't hesitate to drop me a line at: jesperXelectronic-obsession.se

Also please bear in mind that all pictures and texts are mine so, ask before you steal or write your own stuff and take your own pictures! Feel free to link to my pages...