PAiA 9700S (DIY, step-by-step by Tommy)
The P9700S is delivered as four separate kits, one for each module: MIDI-CV converter, VCOs, VCFs and the VCA. The circuit boards are not pre-populated, all the resistors and capacitors have to be soldered by hand. However soldering the parts to the board is pretty easy. The most tedious work is to solder the flying wires, the wires connecting the circuit board to the pots, jacks and switches on the panels. The jacks are a bit sensitive to heat and holding the soldering iron to long against it may cause the jack’s plastic cover to melt.
It took me approximately one working week (40h) to complete the whole kit. It can probably be done faster by someone more experienced than me, but taking the time to get everything right from the start is key to get a working synth in the end. Interchanging two components may cause severe damage to the module when first powering it up. The documentation is very helpful and makes it easy to do the job methodically.
The Paia 9700S does not make use of any pre-manufactured synth chips like CEM or SSM in the audio chain. The only integrated circuits are the OpAmps and comparators etc, except for the MIDI-CV converter, which of course have some digital components. The quality of the pots is excellent with steel shafts and smooth operation. The 1/8'' jacks are small and a bit flimsier than 1/4'' ones, but they make the synth more compact. The patch cables delivered with the kit showed to be more or less unusable. The plugs fit very badly in the jacks which makes it hard to pull them out after inserting them. Often the plastic covers of the plug comes off when trying!
The P9700S must be one of the most compact modular synths there is with lots of functions that may not be evident at a first look; especially the VCA/Mixer which houses a loopable ADSR, a stereo mixer with panorama, ringmodulator and a noise source. There are a lot of helpful normalizations that keeps the number of needed patch cables low. For example, the ADSR is by default connected so it affects the signal passed to the input of the mixer. By connecting something else to the output of the ADSR, the normalization is overridden.
The sound could be described as very vintage, full bodied, and animated. For example when modulating the pulse width with one of the AD-modulators in cycle mode the modulation is not a clean sine wave which results in interesting variations in the sound. The filters are a bit peculiar. High resonance sounds are not its strength in my opinion, being a bit uncontrollable at times (listen to demo Bass1). But having two multimode filters does allow for a lot of possibilities together with the stereo mixer section.
The Paia is cheap compared to a corresponding system from say Doepfer or Analogue Systems but you have to like the idea of building it your self. If you’re not interesting in the building part, don’t buy it just because it is cheaper.
See the finished instrument here.
Bass1: Two oscillators through one low-pass filter each in stereo. Tweaking filter decay, envelope amount and resonance. Some uncontrolled filter resonance can be heard.
Resonant drone: Two oscillators through one band-pass filter each in stereo. Filter cutoff and resonance of both filters tweaked.
Modulated: Cable spaghetti!
Filter_ping_loop: Cable spaghetti!