Interesting stuff there Tony. This would explain the slightly different sounds of both machines even though they use the same filters.Synthbuilder wrote:The SH-101 and Juno-6 filter are not the same. They both use the IR3109 in cascade mode, but the resonance and signal pathways are different.
The Juno uses a VCA in the feedback path, so to allow voltage control over the resonance. This is needed since it has multiple voices and one common resonance control. The SH-101 uses a slider pot and a simple buffer circuit with a diode clipper. The Juno's VCA will also act as a clipper but will present a different type of waveform shaping to the simple diodes.
Furthermore the Juno increases the signal level into the filter at higher resonances to maintain overall volume. While the SH-101 increases the signal to the final VCA at higher resonances. In a linear filter and VCA system this wouldn't make a great deal of difference, but the IR3109 filter and BA662 VCA are non linear components so differing signal levels have an impact on the sound of the system.
Tony
I guess the VCA's were also a requirement due to programmability.
From memory, I always felt the my SH101 could bite a little more then my Juno 106. Although I tended to use both machines for totally different tasks.
OT. I hope Tal is working on a Jupiter clone now.
