The Cyndustries List

Thanks for reporting this, John.  I will go through the calibration 
process again, although I am not sure it will help because I saw too 
much sensitivity on the low end (greater than one octave per volt) and 
not enough on the high end.   I would expect the trimpot only to shift 
the center of the accurate tracking range.  But my procedure was 
different from yours in that I used the Tuning knob to set the initial 
frequency and then applied one volt to the 1V/Oct input.  Then I would 
adjust the Tuning pot up an octave and repeat.  I will instead try 
increasing the CV input one volt at a time while leaving the Tuning 
alone and see if that has different results.

-Richard Brewster
http://www.pugix.com

John Loffink wrote:

>OK, I pulled out my ZO and recalibrated to get the following much much
>better results.  I would say there is a five octave range that is very good
>by analog VCO standards.  I estimate the scale trimmer per the factory
>settings was off by 1.5 to 2 revolutions.
>
>After final recalibration. ZO High Bias, Medium Range, Tuning in mid range,
>base at 239.97	
>Desired Voltage	Input Voltage	Desired Frequency	Actual Frequency
>Error (Hertz)	Error (percent)	Desired Cents	Actual Cents	Difference
>Cents	
>-1	-1.0006	15	14.641	-0.359	-2.39%	-3398.25	-3440.19
>-41.94	
>0	-0.0033	30	29.638	-0.362	-1.21%	-2198.25	-2219.27
>-21.02	
>1	0.9941	60	59.627	-0.373	-0.62%	-998.25	-1009.05
>-10.80	
>2	1.9916	120	119.710	-0.29	-0.24%	201.75	197.56	-4.19	
>3	2.9888	240	239.970	-0.03	-0.01%	1401.75	1401.53	-0.22	
>4	3.9863	480	480.530	0.53	0.11%	2601.75	2603.66	1.91	
>5	4.9837	960	960.140	0.14	0.01%	3801.75	3802.00	0.25	
>6	5.9820	1920	1911.000	-9	-0.47%	5001.75	4993.61
>-8.13	
>
>Compared to my MOTM results from yesterday:
>
>MOTM VCO	
>Desired Voltage	Input Voltage	Desired Frequency	Actual Frequency
>Error (Hertz)	Error (percent)	Desired Cents	Actual Cents	Difference
>Cents	
>-1	-1.0007	15	14.965	-0.035	-0.23%	-3398.25	-3402.30
>-4.04	
>0	-0.0034	30	29.958	-0.042	-0.14%	-2198.25	-2200.68
>-2.43	
>1	0.9940	60	59.954	-0.046	-0.08%	-998.25	-999.58	-1.33	
>2	1.9915	120	119.96	-0.040	-0.03%	201.75	201.17	-0.58	
>3	2.9887	240	239.89	-0.110	-0.05%	1401.75	1400.95	-0.79	
>4	3.9862	480	479.68	-0.320	-0.07%	2601.75	2600.59	-1.15	
>5	4.9837	960	958.23	-1.770	-0.18%	3801.75	3798.55	-3.19	
>6	5.9820	1,920	1912.1	-7.900	-0.41%	5001.75	4994.61	-7.14	
>
>I can get slightly better results for the ZO in the bass registers, to -5.98
>cents at 60 Hertz.  But that occurs at the expense of the higher registers,
>and it is the higher registers that are more sensitive to tuning errors.  I
>doubt that tuning at 15 or 30 Hertz is relevant.  The ZO is now calibrated
>to track the MOTM to within about 3 cents over a five octave range.  You
>can't expect much better than that.
>
>The error (Hertz) difference shows what would be the beat frequency.  This
>is what might cause beats and clangorous tones.  Worst case beat frequency
>is about 2 Hertz, which shouldn't cause the artifacts with indexed FM that I
>described in previous posts.  Mark is working with me offline to understand
>other causes for this.
>
>John Loffink
>The Microtonal Synthesis Web Site
>http://www.microtonal-synthesis.com
>The Wavemakers Synthesizer Web Site
>http://www.wavemakers-synth.com
>
>  
>