grizz Posted November 9, 2010 Report Share Posted November 9, 2010 I'm calibrating my SSM2044 filters from the Seppomen bulk order, and I have a few questions: First off they sound amazing, pre-calibration. Questions: 1. The instructions on the wiki say to adjust breakpoint trimmers, P3 and P4, to "mid" using a multimeter. When I use my multimeter to measure the voltage at the trimmers I can only get a reading (~3.43v) on P1 and P2, but no reading on P3 and P4. Am I missing something? Are P1 and P2 the breakpoint trimmers by chance? 2. By "mid" the wiki means ~5.33v, correct? 3. Do I need to worry about doing extra cutoff adjustments on the AOUT_NG if I already have calibrated the channels with a multimeter? Thanks in advance for responses! grizz Quote Link to comment Share on other sites More sharing options...
seppoman Posted November 9, 2010 Report Share Posted November 9, 2010 1. The instructions on the wiki say to adjust breakpoint trimmers, P3 and P4, to "mid" using a multimeter. When I use my multimeter to measure the voltage at the trimmers I can only get a reading (~3.43v) on P1 and P2, but no reading on P3 and P4. Am I missing something? Are P1 and P2 the breakpoint trimmers by chance? 2. By "mid" the wiki means ~5.33v, correct? P3/P4 are for the breakpoint. This setting is only meant as a starting point and doing measurements there won't give much reasonable readings. Just try the "mechanical" approach - these trimpots usually have 22 turns from one end to the other, so if you turn the trimpot in one direction until it starts making a clicking sound and then turn it back about 11 turns, you're fine. 3. Do I need to worry about doing extra cutoff adjustments on the AOUT_NG if I already have calibrated the channels with a multimeter? yes please do worry :D The SSM module doesn't have any means of adjusting gain and offset of the cutoff, so you will need to use the respective trimpots on the NG to calibrate/tune the filter cutoff. S Quote Link to comment Share on other sites More sharing options...
Imp Posted November 9, 2010 Report Share Posted November 9, 2010 You could also measure the resistance, at least that's what i did. BTW, since you might be reading this Seppoman: Thank you for this fantastic module! I love it! Quote Link to comment Share on other sites More sharing options...
grizz Posted November 9, 2010 Author Report Share Posted November 9, 2010 You could also measure the resistance, at least that's what i did. My trimpots are already soldered. My understanding, forgive me if I am misguided, is that you can't measure the resistance of a specific component if it is already inserted into a circuit. There is no way to isolate it. BTW, since you might be reading this Seppoman: Thank you for this fantastic module! I love it! I agree wholeheartedly! cheers, grizz Quote Link to comment Share on other sites More sharing options...
Imp Posted November 9, 2010 Report Share Posted November 9, 2010 Here is the schematic If you had a resistance in parallel, you would get wrong values indeed, but as you can see in the schematic, if you measure between pins 1 and 2 of P3/P4, there is nothing in parallel. If you measure between pins 2 and 3, there is a 100k resistor and a capacitor in parallel which don't change much. Quote Link to comment Share on other sites More sharing options...
grizz Posted November 10, 2010 Author Report Share Posted November 10, 2010 Here is the schematic If you had a resistance in parallel, you would get wrong values indeed, but as you can see in the schematic, if you measure between pins 1 and 2 of P3/P4, there is nothing in parallel. If you measure between pins 2 and 3, there is a 100k resistor and a capacitor in parallel which don't change much. Thanks for the response. I hadn't thought about it that way, but it makes sense. I'm actually having some troubles setting the resonance on mine. It seems that when I turn the resonance all the way down on the MB-6582 I get a audible buzz, and I can't get them to self-oscillate either. I don't own a scope, so I may try and take everything over to a friend that owns one and make my life a bit easier. I used the caps that Seppoman recommends so I am assuming that I shouldn't have too much trouble reaching self-oscillation. Cheers, grizz Quote Link to comment Share on other sites More sharing options...
grizz Posted December 5, 2010 Author Report Share Posted December 5, 2010 As I try unsuccessfully to get my SSM2044 to self-oscillate I have a question. When using my MB-6582 to calibrate it I should set cutoff and resonance fully open, and turn off all oscillators. I then should play a note (say an E4) on my keyboard (controlling the MB-6582), and adjust the gain (P1) until I get self-oscillation. And the waveform coming from the filter should be close to the note I am playing on the keyboard, correct? The reason I am asking is because this isn't working out for me :sad: Cheers! Quote Link to comment Share on other sites More sharing options...
seppoman Posted December 6, 2010 Report Share Posted December 6, 2010 So is your problem making the filter oscillate or getting a playable/tuned oscillation? Playing well-tuned oscillation isn't as easy as just setting everything to max and play :) The mbsid parameters routed to some target (like cutoff) add up together, so if you set cutoff to max, you're already at the top frequency limit. What you need to do is set keytracking to 127, i.e. output value will track the keyboard position, and then the (initial) cutoff value will be your "master tune". Getting a nice result requires good calibration and some tweaking time. S Quote Link to comment Share on other sites More sharing options...
grizz Posted December 6, 2010 Author Report Share Posted December 6, 2010 Right now I am stuck on trying to get the filter to self-oscillate, and having no luck. Just for clarification, I don't need to have any audio going into the filter to get it to oscillate? I'm using the caps: http://www.newark.com/jsp/search/productdetail.jsp?SKU=97K0250 http://www.newark.com/jsp/search/productdetail.jsp?SKU=97K0287 Maybe I need different resistors on R22 and R23? Quote Link to comment Share on other sites More sharing options...
Imp Posted December 6, 2010 Report Share Posted December 6, 2010 You don't need input to make it oscillate, it doesn't make much difference if there is input or not, cause the ssm is so much louder. While calibrating mine, i found out that if the cutoff-voltage is out of range, the ssm tends to mute everything and adds some noise. Did you invert the cutoff channels? Quote Link to comment Share on other sites More sharing options...
grizz Posted December 6, 2010 Author Report Share Posted December 6, 2010 I inverted the channels, and I can play audio through the filter fine. The cutoff works, and, depending on the gain trimpot setting, when I turn resonance up with the filter open the audio signal gets a tiny bit quieter... No self-oscillation. Quote Link to comment Share on other sites More sharing options...
strophlex Posted January 4, 2011 Report Share Posted January 4, 2011 I inverted the channels, and I can play audio through the filter fine. The cutoff works, and, depending on the gain trimpot setting, when I turn resonance up with the filter open the audio signal gets a tiny bit quieter... No self-oscillation. Did you get this sorted? I have the same problem... Quote Link to comment Share on other sites More sharing options...
grizz Posted January 4, 2011 Author Report Share Posted January 4, 2011 Did you get this sorted? I have the same problem... I haven't yet. To be honest I have a order saved with mouser that I haven't finalized that includes some alternative capacitors to try. grizz Quote Link to comment Share on other sites More sharing options...
strophlex Posted January 4, 2011 Report Share Posted January 4, 2011 I haven't yet. To be honest I have a order saved with mouser that I haven't finalized that includes some alternative capacitors to try. grizz I am using exactly the same caps as seppoman so I doubt that is the reason, at least not for me... Quote Link to comment Share on other sites More sharing options...
grizz Posted January 4, 2011 Author Report Share Posted January 4, 2011 I am using exactly the same caps as seppoman so I doubt that is the reason, at least not for me... Yeah, my intuition makes me think it isn't the caps that I am using, as they have worked for other filters just fine... I'm a little stuck on the cause, so I've been focusing on other projects for a bit... Quote Link to comment Share on other sites More sharing options...
strophlex Posted January 5, 2011 Report Share Posted January 5, 2011 I had a look at the schematic and the SMM2044 datasheet. The datasheet says: "The sense of the Q control is from GND up with minimum resonance at GND." Now, when I measure the voltage at pin 2 of my SMM2044s I get a reading of about -7 to 1 V or -5 to .5 V depending on trimmer setting max / min. It doesn't look right to me. The control voltage into the board is from 0 to 10.6 V which should be right for Q. I don't understand how the LM13700 cirquit works but I guess there is something wrong in there somewhere... Also I have tried another board. Behaves the same. Quote Link to comment Share on other sites More sharing options...
Imp Posted January 5, 2011 Report Share Posted January 5, 2011 I just measured those values: -0.1 to 10.9V into the module and -11v to 1.13v on pins2 of the chips ( from lowest to highest res.) I think those -11v are strange, they only occur, when res is almost turned down completely, when turned up a bit, it jumps to around 0.5v and then can be adjusted precisely until 1.13v, where the filter starts to oscillate. Maybe some more gain on your Aout could help? Quote Link to comment Share on other sites More sharing options...
strophlex Posted January 5, 2011 Report Share Posted January 5, 2011 I just measured those values: -0.1 to 10.9V into the module and -11v to 1.13v on pins2 of the chips ( from lowest to highest res.) I think those -11v are strange, they only occur, when res is almost turned down completely, when turned up a bit, it jumps to around 0.5v and then can be adjusted precisely until 1.13v, where the filter starts to oscillate. Maybe some more gain on your Aout could help? Thanks Imp! Since I know your setup works, now I have something to go on. I think the jumpy voltages might have to do with linear expnential convertion of some cv... Anyway it seems strange to me with all the negative voltages, but it your work, then I guess it is right... I will try with some more juce from the aout... Quote Link to comment Share on other sites More sharing options...
strophlex Posted January 5, 2011 Report Share Posted January 5, 2011 The highest voltage I manage to get out of my aout_ng or rather into my ssm2044 is 11.12 V. This gives pin 2 of the SSM2044 a voltage of 0.84V. The lowest voltage is of course 0 V and that gives a -5.18 on the SSM2044. It seems I don't get enough amplification... The power supply should be close enough to 12 V (-12.15 / +11.85). Now that I look at the numbers from my previous post it looks like I made things worse, but I didn't check them carefully before, so I guess they are about the same... Quote Link to comment Share on other sites More sharing options...
Imp Posted January 6, 2011 Report Share Posted January 6, 2011 (edited) 11.12v should be ok, so the ssm-module seems to be at fault. I'll measure the resistances between lm13700 pins (3,4,13,14,) and ground, and (1,16) and V+ so you can copy my trimpot settings. Maybe this helps... Edit: Results: P3-->GND : 1.424k P14-->GND : 1.43k P4-->GND : 1.07k P13-->GND : 1.05k P1,P16--->V+(P11):26.8k Power was off, Lm13700 was inserted I read some of the datasheet of the lm13700 and if i understood it correctly, the current into P1 and P16 controls the gain. I dont know, how i got a resistance below 27k, because there is a 27k ressistor in series, but this might be what solves your problem. btw: same values without lm13700 Edited January 6, 2011 by Imp Quote Link to comment Share on other sites More sharing options...
strophlex Posted January 6, 2011 Report Share Posted January 6, 2011 Yes! I got some oscillation!!! I didn't expect the callibration to be that tricky, guess I was impatient. Thanks for all your help Imp! :flowers: Quote Link to comment Share on other sites More sharing options...
Imp Posted January 6, 2011 Report Share Posted January 6, 2011 no problem, now go make some xox-owners jealous with it ;) Quote Link to comment Share on other sites More sharing options...
grizz Posted January 6, 2011 Author Report Share Posted January 6, 2011 Yes! I got some oscillation!!! I didn't expect the callibration to be that tricky, guess I was impatient. Thanks for all your help Imp! :flowers: Strophlex: If you have time would you mind listing the steps that led to successful oscillation? I need to get my 4 filters working properly so I can make music with them... cheers, grizz Quote Link to comment Share on other sites More sharing options...
strophlex Posted January 7, 2011 Report Share Posted January 7, 2011 (edited) I adjusted P3 to get 1.43 k ohm between pin 3 of LM13700 and gnd. I adjusted P4 to get 1.43 k ohm between pin 14 of LM13700 and gnd. Then I adjuseted P1 to get 26.8 k ohm between pin 1 and pin 11 of LM13700. That meant turning it all the way counterclockwise. Then I adjuseted P2 to get 26.8 k ohm between pin 16 and pin 11 of LM13700. That meant turning it all the way counterclockwise. I adusted P3 and P4 a bit more to get a bit more resonace, ended up at 1.46 k ohm I think. Now my relays start to die off... EDIT: It seems like it is my crimpings that die off. Hope the relays are OK. Edited January 7, 2011 by strophlex Quote Link to comment Share on other sites More sharing options...
grizz Posted May 8, 2011 Author Report Share Posted May 8, 2011 I adjusted P3 to get 1.43 k ohm between pin 3 of LM13700 and gnd. I adjusted P4 to get 1.43 k ohm between pin 14 of LM13700 and gnd. Then I adjuseted P1 to get 26.8 k ohm between pin 1 and pin 11 of LM13700. That meant turning it all the way counterclockwise. Then I adjuseted P2 to get 26.8 k ohm between pin 16 and pin 11 of LM13700. That meant turning it all the way counterclockwise. I adusted P3 and P4 a bit more to get a bit more resonace, ended up at 1.46 k ohm I think. Now my relays start to die off... EDIT: It seems like it is my crimpings that die off. Hope the relays are OK. After a long time working on other projects I finally replicated your readings, and... OSCILLATION!!!! Thanks for all the help... damn they sound so smooth! cheers, grizz Quote Link to comment Share on other sites More sharing options...
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