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01012k7
Joined: Aug 31, 2013 Posts: 25 Location: England
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Posted: Thu Apr 10, 2014 1:31 pm Post subject:
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Decided to build another MPS after some one giving me a board so its going into my euro rack so far here a few pictures
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P.S Installing a second power supply 15- ov 15+ for mps, Oakley little LFO,ETC |
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jpjsenior
Joined: Jan 04, 2014 Posts: 3 Location: Bristol, UK
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Posted: Thu Apr 17, 2014 3:30 pm Post subject:
Additional power inputs question Subject description: MPS J12 and 19 unsure how to wire |
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Hi there,
I'm about to embark on building a couple of these and I have a question about something I've not come across before that is a bit basic I think, but as it's concerned with something on the MPS boards I thought I would post it here.
Back on page 24 of this thread kkissinger has kindly made a list of the wiring on the board. It shows J11 as where the main power comes in from the power supply. J12 and J19 also are listed as bringing + and - V in. I'm unsure how this works. From looking briefly over the schematics I'm assuming these additional voltages would be 15v. Am I right in thinking that? Would there need to be separate connections from the PSU for these? Or are they something else and if so can anyone guide me towards some info on how to get everything set up power-wise? I have a +/-15V PSU with a distribution board assembled ready for this project. This issue is the only thing stopping me getting on with the soldering at present so any help would be much appreciated,
Thanks,
Jon |
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elmegil
Joined: Mar 20, 2012 Posts: 2177 Location: Chicago
Audio files: 16
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Posted: Thu Apr 17, 2014 4:59 pm Post subject:
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J11 is power in
J12 is power out to the various pots that need it.
Not sure what 19 was for, mine is in the basement and not convenient at the moment; I could check it out later if you need. |
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jpjsenior
Joined: Jan 04, 2014 Posts: 3 Location: Bristol, UK
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Posted: Fri Apr 18, 2014 8:17 am Post subject:
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Thanks man, that makes sense. Gonna spend a bit of time studying the schematic against the boards I reckon before getting started. |
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qfactor
Joined: Jul 19, 2010 Posts: 9 Location: Singapore
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Posted: Sat May 31, 2014 8:39 am Post subject:
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elmegil wrote: | J11 is power in
J12 is power out to the various pots that need it.
Not sure what 19 was for, mine is in the basement and not convenient at the moment; I could check it out later if you need. |
I believe if you have version 107 PCB, there is no more J19,20 and 21, right?
So there's no need to hook those up.
My question is Similar to defog's on the use of +-12V instead of 15v. Do I need to change any resistor/cap values for this, or can I go ahead with everything unchanged?
Thankie! |
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01012k7
Joined: Aug 31, 2013 Posts: 25 Location: England
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Posted: Sat Jun 14, 2014 1:55 pm Post subject:
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I would like to take full credit for this project but I cannot my friend wired the thing up and got it working I did make the front panel and drill the holes and solder the parts on the board with I guess some errors
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davebr
Joined: Jun 09, 2007 Posts: 198 Location: portland, or
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Posted: Thu Nov 20, 2014 6:39 pm Post subject:
Mega Percussive Synthesizer |
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I just finished building a 2U MPS module. I was greatly influenced by sduck's design and tweaked it to fit my modular style. I bought the XR-2206 at Jameco and everything else at Mouser. I have photos and documentation on my MPS Module page http://modularsynthesis.com/electro-music/mps/th-mps.htm
Dave
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elmegil
Joined: Mar 20, 2012 Posts: 2177 Location: Chicago
Audio files: 16
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Posted: Thu Nov 20, 2014 10:13 pm Post subject:
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I'm curious about the reasons for the modifications you listed.... |
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davebr
Joined: Jun 09, 2007 Posts: 198 Location: portland, or
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Posted: Sun Nov 23, 2014 10:04 pm Post subject:
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elmegil wrote: | I'm curious about the reasons for the modifications you listed.... |
I'm not sure who you are asking. If it is my modifications it is simply I bought a lot of 100K potentiometers so want to use them whenever possible. There were four 10Ks that were easy to change to 100K. The second mod is I didn't install the volume control but it is one half of the load on the output capacitor to bleed a charge off of it. I increased the load from 20K to 100K just because I wanted a higher DC resistance. The third mod is simply I wanted a manual trigger.
Dave |
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elmegil
Joined: Mar 20, 2012 Posts: 2177 Location: Chicago
Audio files: 16
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Posted: Sun Nov 23, 2014 10:56 pm Post subject:
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Yes, I was asking you . Some of us have had issues with low output levels, even on the "Synth" level output, and I was curious if anything you modified was perhaps to address that. Obviously not
Thanks Dave! |
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01012k7
Joined: Aug 31, 2013 Posts: 25 Location: England
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Posted: Mon Nov 24, 2014 1:27 am Post subject:
Re: Mega Percussive Synthesizer |
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davebr wrote: | I just finished building a 2U MPS module. I was greatly influenced by sduck's design and tweaked it to fit my modular style. I bought the XR-2206 at Jameco and everything else at Mouser. I have photos and documentation on my MPS Module page http://modularsynthesis.com/electro-music/mps/th-mps.htm
Dave
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looks bigger then 2u looks like full rack which is it 5u ?? you done a great job . I could be wrong on the XR-2206 I got a military spec part as some the other version have a problem which I been told its down to 15v they run better on 12v but then I could be wrong my friend wired the mps and the other one up I just made the boards which is the easy part. |
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01012k7
Joined: Aug 31, 2013 Posts: 25 Location: England
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davebr
Joined: Jun 09, 2007 Posts: 198 Location: portland, or
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Posted: Mon Nov 24, 2014 2:16 am Post subject:
Re: Mega Percussive Synthesizer |
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01012k7 wrote: | looks bigger then 2u looks like full rack which is it 5u ?? you done a great job . I could be wrong on the XR-2206 I got a military spec part as some the other version have a problem which I been told its down to 15v they run better on 12v but then I could be wrong my friend wired the mps and the other one up I just made the boards which is the easy part. |
It is a 5U (height) module, but a 2U wide.
Dave |
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davebr
Joined: Jun 09, 2007 Posts: 198 Location: portland, or
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Posted: Mon Nov 24, 2014 2:19 am Post subject:
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elmegil wrote: | Yes, I was asking you . Some of us have had issues with low output levels, even on the "Synth" level output, and I was curious if anything you modified was perhaps to address that. Obviously not
Thanks Dave! |
I've noticed I can change the output volume by adjusting the trigger sensitivity. At least to me it sound quieter until eventually it stops triggering. I've found that I really need to leave the trigger sensitivity near 0. I haven't gone through the circuit but it is possible that a narrow output pulse from the comparator could not be fully operating the subsequent circuits. Are all three outputs quiet? From the scope images on my web page the Impact looks like +/-2.2V waveform, shell looks like +/-1.1V waveform although with the ring mod on it is up to +/-2.2V, and noise looks like just over +/-1V waveform.
Dave |
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elmegil
Joined: Mar 20, 2012 Posts: 2177 Location: Chicago
Audio files: 16
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Posted: Mon Nov 24, 2014 7:41 am Post subject:
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davebr wrote: |
I've noticed I can change the output volume by adjusting the trigger sensitivity. At least to me it sound quieter until eventually it stops triggering. I've found that I really need to leave the trigger sensitivity near 0. I haven't gone through the circuit but it is possible that a narrow output pulse from the comparator could not be fully operating the subsequent circuits. Are all three outputs quiet? From the scope images on my web page the Impact looks like +/-2.2V waveform, shell looks like +/-1.1V waveform although with the ring mod on it is up to +/-2.2V, and noise looks like just over +/-1V waveform.
Dave |
I'll have to check that, I don't know if I tried that. If I recall correctly, the biggest volume problem was with the shell.
Also: I'd *swear* that Thomas' description on Birth of a Synth says that the Synth level outputs are supposed to be 10Vpp. If I expect them to be closer to line level I wouldn't be so surprised
Not the best time for me to be going and double checking that though... |
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davebr
Joined: Jun 09, 2007 Posts: 198 Location: portland, or
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Posted: Tue Nov 25, 2014 12:56 am Post subject:
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elmegil wrote: | davebr wrote: |
I've noticed I can change the output volume by adjusting the trigger sensitivity. At least to me it sound quieter until eventually it stops triggering. I've found that I really need to leave the trigger sensitivity near 0. I haven't gone through the circuit but it is possible that a narrow output pulse from the comparator could not be fully operating the subsequent circuits. Are all three outputs quiet? From the scope images on my web page the Impact looks like +/-2.2V waveform, shell looks like +/-1.1V waveform although with the ring mod on it is up to +/-2.2V, and noise looks like just over +/-1V waveform.
Dave |
I'll have to check that, I don't know if I tried that. If I recall correctly, the biggest volume problem was with the shell.
Also: I'd *swear* that Thomas' description on Birth of a Synth says that the Synth level outputs are supposed to be 10Vpp. If I expect them to be closer to line level I wouldn't be so surprised
Not the best time for me to be going and double checking that though... |
I updated my web page at http://modularsynthesis.com/electro-music/mps/th-mps.htm with scope images of the levels through each of the three sections. I measured at the source, at the VCA, and at the output. The issue is you are summing three sources, so if you want to keep the output at 10V pk-pk you need to keep the individual sections less than that so they add to 10V pk-pk. The Locked feature makes it easy to measure the levels. Impact is the largest at 4.3V pk-pk, Shell is lower at 2.7V pk-pk and noise is the lowest at 1.3V pk-pk. The overall output with all section at max is 8V pk-pk. Remember, these are measured so there will be some variation between builds.
If you want to increase any of the section levels, just decrease the corresponding mixer resistor R90, R91, or R92. These set the gain at the mixer and 200K sets the gain to 1/2. 100K will set the gain to unity (so it will increase the gain of that section by 2X). If you wanted all at equal output then you could adjust the resistors accordingly but the mix seems about right to me.
If you want to keep the mix then simply increase R77. If you increase it to 200K then the output levels will all double.
Dave |
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elmegil
Joined: Mar 20, 2012 Posts: 2177 Location: Chicago
Audio files: 16
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Posted: Tue Nov 25, 2014 7:26 am Post subject:
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Thank you very much; I will have to go drag my MPS upstairs and compare.... |
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davebr
Joined: Jun 09, 2007 Posts: 198 Location: portland, or
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Posted: Tue Nov 25, 2014 12:14 pm Post subject:
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elmegil wrote: | Thank you very much; I will have to go drag my MPS upstairs and compare.... |
Remember also that if the ring modulator depth is set low then the ring modulator balance affects the shell level output. On mine full CW is louder than full CCW. I put an explanation of that on my site also. I eventually changed the gain of Shell by increasing it 4X and Noise by 2X. Details are on my web page.
I also found that the Impact envelope decay was erratic and added a 51 pF capacitor across R94. The trigger comparator was glitching quite badly and this settled it down. All changes are documented in my Modifications section.
Dave |
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elmegil
Joined: Mar 20, 2012 Posts: 2177 Location: Chicago
Audio files: 16
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Posted: Tue Nov 25, 2014 12:50 pm Post subject:
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Yah, I had noted the effects of the ring mod when I was looking at this before.... That explanation helps too though, thank you again. |
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elmegil
Joined: Mar 20, 2012 Posts: 2177 Location: Chicago
Audio files: 16
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Posted: Tue Nov 25, 2014 10:28 pm Post subject:
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Thanks Dave!
While I had noticed that the ring mod affected the shell volume I don't think I fully understood the trigger sensitivity or the ring mod behavior. I may also have the trigger sensitivity pot wired backwards.
With the notes you gave me here, I was able to get quite serviceable volumes out of my MPS. I'm pretty sure I always set the balance full CCW, but I could see on my scope I definitely get a higher signal with it full CW.
I do think the relative levels are still off a bit, so I think I will make the same R90/R91 changes you have noted on your website, but thank you very much for helping me figure out what I was (apparently; been many months now since I had last messed with it) doing wrong. |
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elmegil
Joined: Mar 20, 2012 Posts: 2177 Location: Chicago
Audio files: 16
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Posted: Tue Nov 25, 2014 11:34 pm Post subject:
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The bugbrand mps_connections_v1.pdf on page 8 and reposted on page 19 as well as this diagram which was made from that source:
http://electro-music.com/forum/phpbb-files/mps_layout_111.jpg
All appear to have things wired such that rotating the sensitivity pot CW makes it *more*sensitive. While that makes sense from a certain perspective, I'm accustomed to setting trigger sensitivities the other way, where the lowest threshold (and threfore highest sensitivity) is with the pot full CCW.
I think that's another contributor to my confusion about levels. I'd set that full CCW expecting to get the best trigger sensitivity when in fact I was doing the opposite. |
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davebr
Joined: Jun 09, 2007 Posts: 198 Location: portland, or
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Posted: Sat Nov 29, 2014 11:46 pm Post subject:
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elmegil wrote: | The bugbrand mps_connections_v1.pdf on page 8 and reposted on page 19 as well as this diagram which was made from that source:
http://electro-music.com/forum/phpbb-files/mps_layout_111.jpg
All appear to have things wired such that rotating the sensitivity pot CW makes it *more*sensitive. While that makes sense from a certain perspective, I'm accustomed to setting trigger sensitivities the other way, where the lowest threshold (and threfore highest sensitivity) is with the pot full CCW.
I think that's another contributor to my confusion about levels. I'd set that full CCW expecting to get the best trigger sensitivity when in fact I was doing the opposite. |
You will note that on my page I have the wiring diagram for Sensitivity reversed so the most sensitive setting is CCW. I also changed the nomenclature to Trigger Level since that is what it is. CCW corresponds to 0V and CW corresponds to +5V so it is more intuitive that CCW is the more sensitive setting.
Dave |
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davebr
Joined: Jun 09, 2007 Posts: 198 Location: portland, or
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Posted: Sat Nov 29, 2014 11:57 pm Post subject:
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elmegil wrote: | Thanks Dave!
With the notes you gave me here, I was able to get quite serviceable volumes out of my MPS. I'm pretty sure I always set the balance full CCW, but I could see on my scope I definitely get a higher signal with it full CW.
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Note that the ring mod balance is asymmetric. R89 sets the output with no audio signal to +7.5V, or the Vcc/2 point. R49 shifts the output of the op-amp by +2.7V / -4.5V so one end of the potentiometer should be louder. The specification calls out for Vcc/2 +/-4V which would be 3.5V to 11.5V. This setup ranges from 3V to 10.2V (if I did the math right). The modulation voltage of course adds to this.
Dave |
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synthcube
Joined: Dec 21, 2011 Posts: 64 Location: boston
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Posted: Thu Sep 10, 2015 9:39 am Post subject:
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To help keep this original thread refreshed, we are posting the recent updates to create a euro- DIY version of the MPS, with a panel by papernoise and panel daughterboard by barcode- which eliminates the need for flying wires to pots, jacks and switches. Sales of each MPS PCB still contribute to the E-M forum consistent with our support of the MPS and Klee PCBs.
http://synthcube.com/cart/megapercussive%20synth
[/img] _________________ web store: www.synthcube.com/cart
we've acquired MFOS to help carry on Ray Wilson's work: www.musicfromouterspace.com |
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col2
Joined: Feb 15, 2014 Posts: 16 Location: Melbourne Australia
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Posted: Wed Oct 07, 2015 6:56 pm Post subject:
MPS with the new Barcode/Papernoise control panel |
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I recently finished a couple of the latest generation MPSs. Thought I would post a link to my photos here for people who don't follow over on MW. The MPS modules work really well and are fairly easy and quick to build once you have all the components at hand.
http://pix.minirig.org.au/main.php?g2_itemId=7387
Wondering if any of the old hands here have any tips for playing? |
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