[sdiy] Interpolating Scanner and Hammond Scanner Vibrato PCB interest?

JH. jhaible at debitel.net
Sun Apr 20 23:43:38 CEST 2008


Hi,

Here's an idea how I could possibly resurrect my Scanner Vibrato project.

Instead of taking another go on a dedicated chorus / vibrato module, I could 
offer a full-fledged Interpolating Scanner with 9 stages, with an option to 
have the inductors on the PCB to turn it into a Hammond Chorus/Vibrato.

That way, the PCB can be used by both, Modular Synth users, and those who 
are looking for a good Hammond Vibrato emulation.

My original Interpolating Scanner is described here (8-stage version):
http://jhaible.heim.at/tonline_stuff/jh_ipscan.html

and the Hammond Vibrato Emulation is here:
http://jhaible.heim.at/scanner_vibrato/jh_scanner_vibrato.html

So the idea is to combine the two projects, hoping there will be enough 
demand for such a PCB to make it a project to be in the black, commercially.

The new version would have 9 stages of linear scanning (to fully cover the 
16 positions of the mechanical rotary Hammond scanner). The scan can be 
performed by *any* modulation source (LFO, envelopes, audio rate, you name 
it) - not just with a LFO as in my earlier scanner vibrato.
All the audio waveshaping capabilities of the Interpolating Scanner would be 
preseved, as well. (Piecewise linear interpolation of fixed, or modulated, 
breakpoints).

The pcb would also include the footprint for 25 inexpensive inductors, plus 
the buffer stages for makeup gain (required with cheap inductors; unlike the 
original Hammond Line Box)

All the interconnections between this inductor delay line and the Scanner 
part would be done mechanically, with switches, just like the real Hammond. 
(No more CMOS switch matrix.)
This also allows to use the board for a generic interpolating scanner with a 
jack for each stage's audio or CV input - with these inputs normalized to 
the Inductor delay line's taps.

No more SSM chips in the new version, either. VCAs will all be discrete, 
built from transistor pairs. (9 transistor pairs like LM394 or similar 
required)

Would this be an interesting project?

JH.




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