ssm2044_pcb
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ssm2044_pcb [2008/08/09 13:46] – external edit 127.0.0.1 | 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:// |
- | {{seppoman:ssm_small.gif? | + | **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: |
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: | {{seppoman: | ||
- | 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 |
Here's a short audio demo: [[http:// | Here's a short audio demo: [[http:// | ||
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TK made a very nice audio demo, too: [[http:// | TK made a very nice audio demo, too: [[http:// | ||
+ | |||
+ | ==== Layout and Schematic ==== | ||
+ | |||
+ | {{seppoman: | ||
+ | |||
+ | (click to enlarge) | ||
+ | |||
+ | {{seppoman: | ||
==== Parts List ==== | ==== Parts List ==== | ||
- | |Part | + | |Part |
- | | | + | | |
- | |C1, | + | |C1, |
- | |C3, | + | |C3, |
- | |C5-C12 | + | |C5-C12 |
- | |C13, | + | |C13, |
- | |C15-C18 | + | |C15-C18 |
- | |C19-C24 | + | |C19-C24 |
- | |C25, | + | |C25, |
- | |D1 | + | |D1 |
- | |IC1, | + | |IC1, |
- | |IC3 |LM13700 | + | |IC3 |LM13700 |
- | |IC4 |TL072P | + | |IC4 |TL072P |
- | |K1 | + | |K1 |
- | |P1, | + | |P1, |
- | |P3, | + | |P3, |
- | |R1-R6 | + | |R1-R6 |
- | |R7-R13 | + | |R7-R13 |
- | |R14, | + | |R14, |
- | |R16, | + | |R16, |
- | |R18, | + | |R18, |
- | |R20,21 |47k | + | |R20,R21,R24-R27|47k |
- | |R22, | + | |R22, |
- | |R24-R27 | + | |R28, |
- | |R28, | + | |T1 |
- | |T1 | + | |
+ | 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:// |
==== Design ==== | ==== Design ==== | ||
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I've found a nice [[http:// | I've found a nice [[http:// | ||
- | 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 **" | + | The consequence of this is: If you want to use this module together with **" |
==== Filter Caps ==== | ==== Filter Caps ==== | ||
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==== Bypass Relay ==== | ==== Bypass Relay ==== | ||
- | The " | + | The " |
+ | |||
+ | 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' | ||
- | 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: |
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/ | 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/ | ||
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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/ | 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/ |
ssm2044_pcb.1218289580.txt.gz · Last modified: 2009/01/17 15:09 (external edit)