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--- ssm2164_getting_started [2018/04/23 13:53] – [Resistor Solution low voltage - seppomans prefered] phatline
+++ ssm2164_getting_started [2018/04/26 19:28] (current) – phatline
@@ Line 1: / Line 1: @@
-======= ssm2164_seppoman pcb - getting started - how to setup =======
+======= ssm2164_seppoman pcb introduction =======
+seppomans building information;[[ssm2164_pcb]]\\
 the following informations are take from the midibox forum, its a collection of infos, without the claim to be 100% true, i will try to test the given information.
+====== Shematic ======
+not found anywhere... m( \\
+also reverse engeniering/understanding/troubleshooting/moding is nearly impossible when the pcbs are stuffed, because most of the traces are on the component site... or hidden behind the black paint\\\
+--- first i want to know for what are those POTs? Input Gain of Audio? or of CV? or some BIAS? seppoman said nothing...\\
+POT P1 middle & right Pin connected to VCC-\\
+POT P1 left Pin connected to a 27K Resistor and this resistor to a nother 27K Resistor which is connected to CV1+ Input. the middle point of this2xresistors is going to the TL74-OP-Amp Pin1 which is a inverting input...\\
+The Output of this TL74 Stage is Pin1: its connected to Pin 6 SSM2164, which is the CV-Input\\
+When i measure Pin6 to Ground, and Turn P1 most left:1,8V... Turn P1 most right: 2,47V\\
+so what does it? no one said: its a zero offset for bipolar cv? or is it gain-control? FIXME m( \\
 ====== Power ======
@@ Line 43: / Line 55: @@
 ==== Resistor Solution low voltage - seppomans prefered ====
 **R9...R16 > 5.6k** (only on the channels that are setup for bipolar mode)\\
-**+-3.5V to +-5.8V** Bi-Polar calibration range
+**+-3.5V to +-5.8V** Bi-Polar calibration range\\
 **Pro:** easy job, still have a decent precision when calibrating.\\
 **Con:** “just change the jumpers if you need some channel in bipolar mode” thought will not work. (FIXME really?)
-==== Resistor Solution Stock - NorthernLightX prefered ====
+==== Resistor Solution Stock - -5V Level shifter - NorthernLightX prefered ====
 we came to the conclusion that it's probably much easier to have the AOUT only output **unipolar 0 to 10 volt**, and design **a simple -5v level shifter board** that can be used as an add-on (or separate module with hands-on access to the level shifting) to **shift the output to -5 to +5 volt** where needed.\\
@@ Line 66: / Line 78: @@
 **Pro:** preserve the "just change the jumpers if you need some channel in bipolar mode" thought behind this option.\\
 **Con:**dramatically increase the calibration range, i.e. exactly calibrating the outputs will get harder because the same angle of turning the pot will have much more impact.\\
+====== MODs ======
+===== MODE Resistor - Noise vs Distortion =====
+SSM2164 Pin 1 (the first pin) sets the "Mode"
+==== Class AB ====
+Pin 1 is Open, no Resistor to +12V (PCB Default)\\
+Lower  current results in higher distortion/lower noise.\\
+---i do want distortion and dont care about noise--- so i do not change anything, the pcb is fine.
+==== Class A ====
+Pin 1 is Connected to +12V via a Resistor\\
+Higher current results in lower distortion/higher noise\\
+lets look in the datasheet:\\
+{{:phatline:ssm2164-ab-a.png?600|}}\\
+Figures 11 and 12 show the THD and noise performance of the
+SSM2164 as the bias current is adjusted\\
+I_MODE = ( (V+)−0.6V )/ RB\\
+,52mA = (12V-0.6V) / 7,5K\\
+Leaving the MODE pin open sets the SSM2164 in Class AB with 30 μA in the Gain-Core\\