MQ1 custom synthesizer for MENG QI

Published on Jun 23, 2015 noystoise

more info at www.noystoise.com

The following is just a small portion of the full post on noystoise and a couple of pics to give you an idea of what went into this custom synth for Meng Qi, know for his own designs, including modifications of Ciat-Lonbarde creations.  Be sure to see the full post for full specs, build details and more pics.

via noystoise:

"After some back and forth, we came up with a general formula for the synth-to-be. it would be comprised of two sequencers with capacitive-touch sensors, two voices with analog filters, frequency modulation, reverb, a few modular inputs and outputs, and a Meng Qi logo. knowing that this would likely turn in to a pretty large and time consuming project, i quickly got to work designing synth. the project did end up taking almost two months to design and build, but actually, it could have taken much longer and i am actually kind of impressed with how quickly this one came together, considering the complexity of the build...

The signal path of this synth is pretty straight forward, but extremely fun to play. basically the circuit starts out with two square wave voltage-controlled oscillators. the oscillators have a pretty wide range, from high to low. I probably should have measured.. the oscillators' pitch is controlled by its own respective 8-step sequencer. each step can be manually tuned with a pretty decent amount of stability, considering the range. the sequencers are driven by a single clock signal, or they can be triggered individually by an external gate input via the respective input jack. each clock input signal, whether internal or external, is sent through a frequency multiplier, and then a divider, before being sent to the sequencer clock input. the multiplier has four settings; X1, X3, X4, and X5. the frequency multiplication is achieved through the use of a CD4046 phase-locked-loop circuit. at lower frequencies, the PLL takes longer to latch on to the multiple, but eventually it ramps up or down until it is in sync. it is actually kind of a neat affect because the sequencer will sound kind of glitch for a while, and then gradually falls into sync, and then totally syncs up. this made it tricky for the external input though, because the PLL is looking for regular intervals, so if you were manually triggering the sequencer or you had a pattern sequencer running to the input, the multiple would be all kinds of crazy.."