Modular Synth Panels

I'm not sure a circular (or elliptical) pattern would be applicable to  
this circuit because it does not scan in a circle, it scans up and  
down. I think something more like Dave Brown's design would be better,  
although it does necessitate small knobs for the 9 inputs. However,  
the remainder of the panel could spread the controls out a bit more.

I haven't built my scanner/vibrato yet, but I have worked out a list  
of elements that the panel will require. Anybody want to take this on  
and try to design something?

Required:

1. Audio In/Out: 2 jacks (IN and OUT)
2. Interpolating Scanner Controls: 9 jacks (IN), 9 pots (LEVEL), 9 LEDs
3. LFO Rate Control: 1 jack (RATE CV IN), 2 pots (RATE, RATE CV)
4. LFO Depth Control: 1 jack (DEPTH CV IN), 2 pots (DEPTH, DEPTH CV)
5. Scan Control: 1 jack (SCAN CV IN), 2 pots (MANUAL, SCAN CV)
6. Lag Control: 1 switch
7. Chorus/Vibrato control: 1 switch (see *note 1)
8. Function control: 9 pin 4 pole rotary switch

Optional:

1. Input attenuator (for Vibrato/Chorus): 1 pot
2. Lowpass filter (for Vibrato/Chorus): 1 pot
3. Celeste control (for Vibrato/Chorus): 1 switch (see *note 2)

*Note 1
There are several possibilities for the Chorus/Vibrato control:
a. 1 switch (as shown in the schematics)
b. 1 pot (as Dave Brown did)
c. 1 switch and 1 pot (as JH did)

*Note 2
Here's what JH had to say about the Celeste switch:

"Celeste is an option for which no on-board connector is provided,  
namely removing the termination resistor of the delay line, R104, from  
the circuit and thus causing reflections of the delayed signal back  
towards the input of the delay line. If you want to implement this,  
lift one side of R104 from the PCB, and re-connect it via a switch."

Here's what Dave Brown had to say about the Celeste switch:

"The Celeste switch adds a 0.01 uF and 2K resistor in series with R104  
to mis-terminate the delay line causing reflections.  I selected these  
values empirically."

Sounds like there is some room for experimenting with the Celeste  
option. It's possible that a pot could be used to control the level of  
mis-termination, but someone would need to verify whether or not this  
is worthy of taking up panel space. Having a Celeste switch is  
probably worthwhile.


>
> Will and I were discussing this just last night and have decided to  
> do a combined unit.  A 3U panel would be fine - or four.  I occurred  
> to us that a panel similar to the elliptical Klee could probably be  
> implemented in four units.  And we'd be fine with that too.  In  
> fact, there are particular advantages to that implementation... one  
> being that it would graphically represent the rotary nature of the  
> original Hammond scanner.  FWIW.  Bill (and Will)