[sdiy] MS-20 tempco (was Model D service)

[Tony Kalomiris]

One more thing. This exponential keyboard did not produce perfect octaves.
C1= 1.047, C2= 2.092, C3= 4.185, C4=8.383 V , as I measured with my 4 1/2 digit Beckman Industrial.
The lowest octave has the highest resolution. 



On 2017-05-09, at 3:46 AM, Tony Kalomiris wrote:

> Also a cost cutting measure.
> Strange how the modulation on the MS-20 sounded so "musical" and yet the same arrangement on the Jupiter-6 (exp.Fm) sounds like sh*t.
> 
> 
> On 2017-05-09, at 3:37 AM, Tony Kalomiris wrote:
> 
>> Yes excellent description Roman, thanks.
>> 
>> Only downside was this was limited to 3 1/2 (0 ~ 8.4 V) or 4 octaves (MaxiKorg) , as opposed to ten octaves of exponential input. (VCO 1+2)
>> 
>> On 2017-05-09, at 3:20 AM, Roman Sowa wrote:
>> 
>>> The expo pair in MS20 is used only for modulation and external V/oct sources, while keyboard pitch is provided as linear voltage (Hz/V) derived from stable source. So without any modulation, at ballanced state of the pair, when there's 0V between bases, the VCO core current is not dependent on those transistors and their temperature effects.
>>> 
>>> That's one of the beauties of Hz/V systems, it's so easy to make the pitch stable.
>>> 
>>> Roman
>>> 
>> 
>