ssm2044_pcb
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ssm2044_pcb [2008/08/09 13:46] 127.0.0.1 external edit |
ssm2044_pcb [2016/06/22 00:25] (current) psykhaze |
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| - | ==== Dual SSM 2044 VCF ==== | + | ====== Dual SSM 2044 VCF ====== |
| - | [[SSM2044 PCB Bulk Order]] | + | [[http://midibox.org/forums/index.php?/topic/13999-mbhp-eth-mbhp-sdcard-ssm2044-ssm2164-pcb-bulk-order|SSM2044 PCB Bulk Order]] |
| - | {{seppoman:ssm_small.gif?850x*}} | + | **Warning:** This is not a suitable project for absolute beginners. The soldering isn't very difficult, but you will need either an AOUT_NG (SMT soldering required), an AOUT module (which needs to be expanded with the bipolar option) or two (!) AOUT_LC modules, or another type of CV source to control this module, in addition to the actual synth (SID/FM) you want to use it with. So a bit of soldering experience and knowledge about the MidiBox platform is definitely recommended. |
| - | (click to enlarge) | + | {{seppoman:ssm3.jpg?850x*}} |
| This PCB contains two of the famous SSM2044 24dB low pass filters with the necessary circuitry, additional LM13700 based Q linearization circuit and a tiny Omron micro relay for a software controlled (via gate out pins) bypass function. The layout is optimized for use with the [[aout_ng|AOUT_NG]] module, requiring the addition of a bipolar option when used with regular V/Oct sources like the original AOUT module. | This PCB contains two of the famous SSM2044 24dB low pass filters with the necessary circuitry, additional LM13700 based Q linearization circuit and a tiny Omron micro relay for a software controlled (via gate out pins) bypass function. The layout is optimized for use with the [[aout_ng|AOUT_NG]] module, requiring the addition of a bipolar option when used with regular V/Oct sources like the original AOUT module. | ||
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| {{seppoman:ssm2.jpg}} | {{seppoman:ssm2.jpg}} | ||
| - | My current test setup, a MBSID V2 ([[wilba_mb_6582|MB-6582 base PCB]]) with 6581 SIDs and an [[aout_ng|AOUT_NG]]. | + | My prototyping setup, a MBSID V2 ([[wilba_mb_6582|MB-6582 base PCB]]) with 6581 SIDs and an [[aout_ng|AOUT_NG]]. |
| Here's a short audio demo: [[http://www.seppoman.de/stuff/SSMtest2.mp3]] | Here's a short audio demo: [[http://www.seppoman.de/stuff/SSMtest2.mp3]] | ||
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| TK made a very nice audio demo, too: [[http://www.midibox.org/forum/index.php/topic,11460.0.html]] | TK made a very nice audio demo, too: [[http://www.midibox.org/forum/index.php/topic,11460.0.html]] | ||
| + | |||
| + | ==== Layout and Schematic ==== | ||
| + | |||
| + | {{seppoman:ssm_small.gif?300x*}} | ||
| + | |||
| + | (click to enlarge) | ||
| + | |||
| + | {{seppoman:ssm2044_schematic.pdf|Schematic}} | ||
| ==== Parts List ==== | ==== Parts List ==== | ||
| - | |Part |Value |Reichelt No. | | + | |Part |Value |Reichelt No. | |
| - | | | | | | + | | | | | |
| - | |C1,C2 |220 uF |RAD 220/25 | | + | |C1,C2 |220 uF |RAD 220/25 | |
| - | |C3,C4 |10uF |RAD 105 10/63 | | + | |C3,C4 |10uF |RAD 105 10/63 | |
| - | |C5-C12 |100nF |Z5U-2,5 100N | | + | |C5-C12 |100nF |Z5U-2,5 100N | |
| - | |C13,C14 |100pF |NPO-2,5 100P | | + | |C13,C14 |100pF |NPO-2,5 100P | |
| - | |C15-C18 |470nF |Z5U-5 470N | | + | |C15-C18 |470nF |Z5U-5 470N | |
| - | |C19-C24 |10nF |STYROFLEX 10N | | + | |C19-C24 |10nF |STYROFLEX 10N | |
| - | |C25,C26 |820pF |STYROFLEX 820P | | + | |C25,C26 |820pF |STYROFLEX 820P | |
| - | |D1 |1N4148 |1N 4148 | | + | |D1 |1N4148 |1N 4148 | |
| - | |IC1,IC2 |SSM2044 | | | + | |IC1,IC2 |SSM2044 | | |
| - | |IC3 |LM13700 |LM 13700 DIL | | + | |IC3 |LM13700 |LM 13700 DIL | |
| - | |IC4 |TL072P |TL 072 DIP | | + | |IC4 |TL072P |TL 072 DIP | |
| - | |K1 |G6K-2P |G6K-2P 12V | | + | |K1 |G6K-2P |G6K-2P 12V | |
| - | |P1,P2 |10k |64W-10K | | + | |P1,P2 |10k |64W-10K | |
| - | |P3,P4 |500 |64W-500 | | + | |P3,P4 |500 |64W-500 | |
| - | |R1-R6 |220 |METALL 220 | | + | |R1-R6 |220 |METALL 220 | |
| - | |R7-R13 |1k |METALL 1,00K | | + | |R7-R13 |1k |METALL 1,00K | |
| - | |R14,R15 |100 |METALL 100 | | + | |R14,R15 |100 |METALL 100 | |
| - | |R16,R17 |10k |METALL 10,0K | | + | |R16,R17 |10k |METALL 10,0K | |
| - | |R18,R19 |24k |METALL 24,0K | | + | |R18,R19 |24k |METALL 24,0K | |
| - | |R20,21 |47k |METALL 47,0K | | + | |R20,R21,R24-R27|47k |METALL 47,0K | |
| - | |R22,R23 |27k |METALL 27,0K | | + | |R22,R23 |27k |METALL 27,0K | |
| - | |R24-R27 |47k |METALL 47,0K | | + | |R28,R29 |100k |METALL 100K | |
| - | |R28,R29 |100k |METALL 100K | | + | |T1 |BC547 |BC 547C | |
| - | |T1 |BC547 |BC 547C | | + | |
| + | Total cost of all parts (without SSMs): about 11.50 Euros | ||
| - | Total cost of all parts (without SSMs): about 13 Euros | + | nILS did a Reichelt [[https://secure.reichelt.de/?;ACTION=20;LA=5010;AWKID=137885;PROVID=2084|Reichelt public shopping cart]], thanks for that :) |
| ==== Design ==== | ==== Design ==== | ||
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| I've found a nice [[http://www.emulatorarchive.com/assets/PDF/SSM2033%20SSM2044%20Circuits.pdf|article from the 80ies]] where the CA3080 OTA is used to linearize the response. The CA3080 has recently become an obsolete part, you can still buy them, but they're getting quite expensive. So I adapted the design to work with the alternative LM13700 and tweaked the values until the behaviour was to my taste. | I've found a nice [[http://www.emulatorarchive.com/assets/PDF/SSM2033%20SSM2044%20Circuits.pdf|article from the 80ies]] where the CA3080 OTA is used to linearize the response. The CA3080 has recently become an obsolete part, you can still buy them, but they're getting quite expensive. So I adapted the design to work with the alternative LM13700 and tweaked the values until the behaviour was to my taste. | ||
| - | Another problem with the 2044 is that it produces some crackling noises when the CV changes are steppy (like the output of a DAC is). This was cured by adding a few capacitors to the control lines that low pass (smoothe) these little steps. | + | Another problem with the 2044 is that it produces some crackling noises when the CV changes are steppy (like the output of a DAC is). This was cured by adding a few capacitors to the control lines that low pass (smooth) these little steps. |
| The control summer found in all the documented designs on the web was removed. The frequency input of the 2044 expects an input of about -100..+100mV. The mentioned cirquit adapts that onto the standard V/Oct CV range. But this also means you would first need to adjust offset and gain of this cirquit to make the SSM input conform to that standard and then calibrate the output of your AOUT module to also comply with this standard. V/Oct is certainly important in a completely analog modular synth where several analog control sources are mixed and fed to that input, but in a situation where the AOUT is the only source, this conformity is not good for anything. So removing this stage of complexity reduces size and cost and takes away another level of necessary calibration. | The control summer found in all the documented designs on the web was removed. The frequency input of the 2044 expects an input of about -100..+100mV. The mentioned cirquit adapts that onto the standard V/Oct CV range. But this also means you would first need to adjust offset and gain of this cirquit to make the SSM input conform to that standard and then calibrate the output of your AOUT module to also comply with this standard. V/Oct is certainly important in a completely analog modular synth where several analog control sources are mixed and fed to that input, but in a situation where the AOUT is the only source, this conformity is not good for anything. So removing this stage of complexity reduces size and cost and takes away another level of necessary calibration. | ||
| - | The consequence of this is: If you want to use this module together with **"non-AOUT" CV sources**, you will need to **add the control summer cirquit externally** (I'll publish a schematic for it soon). And, if you're using the module together with the **classic AOUT** module, you will need to add the **bipolar option** (as documented on the AOUT page) at least for both frequency channels (normally AOUT1 and AOUT3). | + | The consequence of this is: If you want to use this module together with **"non-AOUT" CV sources**, you will need to **add the control summer circuit externally** (I'll publish a schematic for it soon). And, if you're using the module together with the **classic AOUT** module, you will need to add the **bipolar option** (as documented on the AOUT page) at least for both frequency channels (normally AOUT1 and AOUT3). |
| ==== Filter Caps ==== | ==== Filter Caps ==== | ||
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| ==== Bypass Relay ==== | ==== Bypass Relay ==== | ||
| - | The "bypass" function of the module in fact is an "activate" signal, i.e. the bypass pin expects a logic high signal (5V) to actually engage the filter (for both channels). This behaviour might seem a bit uncommon, but that way you can connect the pin to one of the gate out pins on either the Core or the (MAX525) AOUT module, so you can store the state of the filter together with your Bankstick patches. | + | The "bypass" function of the module in fact is an "activate" signal, i.e. the bypass pin expects a logic high signal (5V) to actually engage the filter (for both channels). This behaviour might seem a bit uncommon, but that way you can connect the pin to one of the gate out pins on either the Core or the (MAX525) AOUT module, so you can store the state of the filter together with your Bankstick patches. To use the bypass function on MBSID, set "#define DEFAULT_J5_FUNCTION 3", recompile and upload, then connect one of core:J5's pins to J3 of the SSM module. Now you can turn the filter on and off by toggling the respective S#1...S#8 setting in the EXT menu. |
| + | |||
| + | If you don't need this function, you can also solder two bridges instead of the relay (as shown below) and leave out R7, D1 and T1. That'll make the filter permanently active. | ||
| - | If you don't need this function, you can also solder two bridges instead of the relay and leave out R7, D1 and T1. | + | {{seppoman:ssm_bypass.gif}} |
| The Omron G6K-2P relay is available at several common places like Mouser, Digikey, Reichelt etc, but is a bit on the expensive side. If space is no issue, you could also use some short wires to solder in a different larger/cheaper/available 12V DPDT relay. | The Omron G6K-2P relay is available at several common places like Mouser, Digikey, Reichelt etc, but is a bit on the expensive side. If space is no issue, you could also use some short wires to solder in a different larger/cheaper/available 12V DPDT relay. | ||
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| ==== Calibration ==== | ==== Calibration ==== | ||
| - | (These instructions are for MBSID V2 in combination with an [[aout_ng|AOUT_NG]], instructions for other AOUT versions will be provided later). | + | (These instructions are for MBSID V2 in combination with an [[aout_ng|AOUT_NG]]). |
| For MBSID, the standard channel assignment is CV1 and CV3 for cutoffs, CV2 and CV4 for resonance. First calibrate the [[aout_ng|AOUT_NG]] to normal V/Oct like described on the NG page. Then in the EXT menu of the ensemble, turn on F2A (Filter cutoff/resonance routed to AOUT 1,3) and Iv1/Iv3 (invert AOUT 1/3). Then in the FIL menu of the ensemble, increase the Max param to FFF, turn off Log. | For MBSID, the standard channel assignment is CV1 and CV3 for cutoffs, CV2 and CV4 for resonance. First calibrate the [[aout_ng|AOUT_NG]] to normal V/Oct like described on the NG page. Then in the EXT menu of the ensemble, turn on F2A (Filter cutoff/resonance routed to AOUT 1,3) and Iv1/Iv3 (invert AOUT 1/3). Then in the FIL menu of the ensemble, increase the Max param to FFF, turn off Log. | ||
ssm2044_pcb.1218289580.txt.gz · Last modified: 2009/01/17 15:09 (external edit)
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