This is the Orchestra2 I found on the basement of a music shop around here. It was all covered with dirt and black material coming from a fire. The most part of the warehouse was destroyed in the fire. It happened on new year’s eve of the last year! This is what I got for 50 euros, the body in the trunk:
The metal surface seemed scattered with rust (but it wasn’t the case, as it turned out later….).
When I turned on the unit no sound was output AND only the rightmost buttons (preset selection) were functional. There are plenty of information on the net on this little synth and I bought the schematics (service manual) from MusicParts. When I opened the unit (see pic below), the interior was surprisingly cleaner than the outside, and I started looking for bad things (burnt traces, exploded caps, torn IC pins, detached ribbon cables, but nothing came to my sight…
After having take the caps of the many sliders and started unscrewing the board on the left (equalizer, lfo, etc..) I noticed this:
The synth probably suffered from a really bad impact with something on the rightmost section of the front panel. The metal sliders broke the board and cut at least thirty traces.
After cleaning the board and jointing with fresh solder and a little wire the broken traces I re assembled the unit and tried to have more luck. I succeded! the unit played again and I tried all the controls (presets, lfo modulations, flanger etc..) that worked good. The only remaining points are: the ‘odd’ pitch bender (a simple slider) is probably broken (as I have to ‘touch’ it to obtain a tone out of the main oscillator), the LFO speed slider need some cleaning and the keyboard is functioning only in part. For the latter I simply used a cotton stick and some alcohol. After a few applications the keys are now functional. In the next few days I will complete the repairs and I hope to make a couple of quick songs around those lovely and deep analog sounds….
I obviuosly cleaned the outside (paper and alcohol) obtaining a good appearance, what I thought were rust points were only greasy black dirt, maybe coming from the smoke of the fire. Now the keyboard is in good shape and it’s possible again to play it like someone did 26 years ago!
Some History and considerations:
The SIEL Orchestra2 was a full polyphonic string/brass/piano/reeds machine produced in Italy form 1983. It sported a very good bang for the buck, in fact the textures, especially layering the different preset, are really organic and even the naive piano sounds good with a little reverb. The limit of the SINGLE filter (a state variable op-amp filter) is hindered by the lushness of the basic waveforms and by the ‘Animator’, a not su subtle, to say the least, flanger.
The basic architecture, then, is built around a Top Octave Generator (SGS M086) and some gate/dividers (TDA1008 from Siemens), exactly like the most part of the organs of that period. Each key had his own basic envelope and sound generation. The basic waveform, righ out of the dividers, is a square, but a simple R/C network transformed it in a kind of sawtooth, filtered in different manners depending on the preset.
This simple architecture (remember, there is NO CPU in this unit!) made for a very cheap but highly functional product.
One last look, the ergonomics and mechanical design of the Orchestra2 are, in my opionion, really good: its triangular shaped cheeks and the beige on brown graphics are something ‘interesting’ on a design point of view. The synth had two retractable feet on the bottom that put the unit in a very inclined position, ideal to play it on the highest tier of a keyboard stand.
Hope you enjoyed the report!