From analogue-request@magnus.acs.ohio-state.edu Thu Jul 15 15:19:51 1993 Received: by quark.magnus.acs.ohio-state.edu (5.65/3.910213) id AA03865; Thu, 15 Jul 93 15:17:34 -0400 Errors-To: analogue-request@magnus.acs.ohio-state.edu Sender: analogue-request@magnus.acs.ohio-state.edu Received: from ncar.ucar.edu by quark.magnus.acs.ohio-state.edu (5.65/3.910213) id AA03842; Thu, 15 Jul 93 15:17:18 -0400 Received: from stout.atd.ucar.edu by ncar.ucar.EDU (5.65/ NCAR Central Post Office 03/11/93) id AA24167; Thu, 15 Jul 93 13:17:14 MDT From: cook@stout.atd.ucar.EDU (Forrest Cook) Received: from bitter.atd.ucar.edu by stout.atd.ucar.EDU (5.65/ NCAR Mail Server 04/10/90) id AA26637; Thu, 15 Jul 93 13:17:12 MDT Date: Thu, 15 Jul 93 13:17:10 MDT Message-Id: <9307151917.AA01660@bitter> Received: by bitter (4.1/ NCAR Mail Client 04/19/90) id AA01660; Thu, 15 Jul 93 13:17:10 MDT To: analogue@magnus.acs.ohio-state.edu Status: OR Pro-One envelope mod again (WITH SCHEMATIC) Ok, there's been enough interest in the envelope inverter mods to the Sequential Circuits Pro-One that I'll post the circuit. First off, you should have SOME experience working with a soldering iron and circuit boards before attempting this. The results are that you can almost double the repertoir of sounds available on the synth. I've been toying with the idea of putting this same mod on my Odyssey, more on that when I get around to it. 1: unplug the unit. 2: remove the screws that hold the top and bottom together. 3: remove all of the knobs. 3: At this point you should start observing standard static procedures, ground your hands to the chassis before touching the innards of the PC board and refrain from shuffling across wool rugs before touching the board. 4: remove the circuit board from the top of the case. 5: Locate U116, one of the Curtis 3310 envelope generator ICs that has lots of traces running to the envelope ADSR potentiometers. On the top of the board there is a 24K resistor going from U116 pin 10 to U116 pin 2. Leave this connection but follow the trace on the pin 2 side, the line runs off to the "envelope amount" pot, cut this trace. Call the U110 pin side of the cut "f-env" and the other side "f-mod" 6: Build a standard circuit for an inverting amp, gain of 1 with a 741 Op-Amp as follows: input: 10K resistor connects to 741 pin 2. Feedback: 10K resistor connects from pin 2 (-) to pin 6 which is the output. Bias: connect a 4.7K resistor from pin 3 (+) to the center tap of a 10K trimmer pot, 10 turn type is best. Connect one side of the trimmer to ground and the other side to the +15 Volt bus. 7: Wire the 741 power: pin 4 goes to -15V and pin 7 goes to +15V. I put a 0.01 uF cap from pin 4 to ground and pin 7 to ground for supply bypass. 8: Mount a single pole double throw switch wherever you can, I put mine on the back panel between the cutoff and resonance knobs. Top mounting would be a bit easier to use but I wanted to retain the original appearance. 9: Connect the free end of the input 10K resistor to U116 pin 2. 10:connect the center of the SPDT switch to the "f-mod" line. 11:connect one end of the SPDT switch to the "f-env" line. 12:connect the other end of the SPDT switch to the inverter output, 741 pin 6. 13:double check your wiring, look for solder bridges and loose bits of solder. 14:reassemble the unit. 15:adjust the bias trimmer for best response. This is a subjective adjustment. I set up a good sounding non-inverted envelope with the filter cutoff around 5, flipped the invert switch, and adjusted the trimmer while playing until I got a reasonable sound. Play with it. Hints: I suggest using the shortest wires possible, my construction involved putting the 8 pin 741 IC into a 14 pin wire-wrap socket and soldering two of the unused pins of the socket to a big ground plane on the back of the board for a stable mounting point. I soldered the resistors onto the socket before mounting the socket. I drilled a hole near the cut trace in step 5 to run the f-mod and f-env signals to the inverter. Make sure you don't hit a trace on the other side of the board. The ground line is easy to find, all of the envelope pots have their metal cases soldered to it. To find the + and - 15V lines, carefully measure the voltages on the board near the power supply regulator section, look for the heat sinks until you find + and - 15V relative to ground. If that doesn't make sense to you, try tapping off of a known IC's supply pins, TL082 chips have -15 on pin 4 and +15 on pin 8. Parts are available from any reputable electronics store and Ratty-ol'-Hack stores as well. That's it, be careful, don't fry anything (including yourself). Nyooooweet Nyooooweet Nyoooweet... f-env -------------------------------- | 10K | | --/\/\/\-- | Normal | | | ----O +15V | | +15V | -----0---- f-mod | | 10K | 2|\| | ----O / |-/\/\/\----|---|-\7 | | Invert \ 3| \6_|____| /<--------/\/\/\--------|+ / \ 4.7K 741 | /4 / |/| | -15V Ground From analogue-request@magnus.acs.ohio-state.edu Thu Jul 15 00:41:14 1993 Received: by quark.magnus.acs.ohio-state.edu (5.65/3.910213) id AA23275; Thu, 15 Jul 93 00:39:34 -0400 Errors-To: analogue-request@magnus.acs.ohio-state.edu Sender: analogue-request@magnus.acs.ohio-state.edu Received: from ncar.ucar.edu by quark.magnus.acs.ohio-state.edu (5.65/3.910213) id AA23269; Thu, 15 Jul 93 00:39:30 -0400 Received: from stout.atd.ucar.edu by ncar.ucar.EDU (5.65/ NCAR Central Post Office 03/11/93) id AA28162; Wed, 14 Jul 93 22:39:28 MDT Date: Wed, 14 Jul 93 22:39:27 MDT From: cook@stout.atd.ucar.EDU (Forrest Cook) Message-Id: <9307150439.AA29415@stout.atd.ucar.EDU> Received: by stout.atd.ucar.EDU (5.65/ NCAR Mail Server 04/10/90) id AA29415; Wed, 14 Jul 93 22:39:27 MDT To: analogue@magnus.acs.ohio-state.edu Status: OR Ok, there's been enough interest in the envelope inverter mods to the Sequential Circuits Pro-One that I'll post the circuit. First off, you should have SOME experience working with a soldering iron and circuit boards before attempting this. The results are that you can almost double the repertoir of sounds available on the synth. I've been toying with the idea of putting this same mod on my Odyssey, more on that when I get around to it. 1: unplug the unit. 2: remove the screws that hold the top and bottom together. 3: remove all of the knobs. 3: At this point you should start observing standard static procedures, ground your hands to the chassis before touching the innards of the PC board and refrain from shuffling across wool rugs before touching the board. 4: remove the circuit board from the top of the case. 5: Locate U116, one of the Curtis 3310 envelope generator ICs that has lots of traces running to the envelope ADSR potentiometers. On the top of the board there is a 24K resistor going from U116 pin 10 to U116 pin 2. Leave this connection but follow the trace on the pin 2 side, the line runs off to the "envelope amount" pot, cut this trace. Call the U110 pin side of the cut "f-env" and the other side "f-mod" 6: Build a standard circuit for an inverting amp, gain of 1 with a 741 Op-Amp as follows: input: 10K resistor connects to 741 pin 2. Feedback: 10K resistor connects from pin 2 (-) to pin 6 which is the output. Bias: connect a 4.7K resistor from pin 3 (+) to the center tap of a 10K trimmer pot, 10 turn type is best. Connect one side of the trimmer to ground and the other side to the +15 Volt bus. 7: Wire the 741 power: pin 4 goes to -15V and pin 7 goes to +15V. I put a 0.01 uF cap from pin 4 to ground and pin 7 to ground for supply bypass. 8: Mount a single pole double throw switch wherever you can, I put mine on the back panel between the cutoff and resonance knobs. Top mounting would be a bit easier to use but I wanted to retain the original appearance. 9: Connect the free end of the input 10K resistor to U116 pin 2. 10:connect the center of the SPDT switch to the "f-mod" line. 11:connect one end of the SPDT switch to the "f-env" line. 12:connect the other end of the SPDT switch to the inverter output, 741 pin 6. 13:double check your wiring, look for solder bridges and loose bits of solder. 14:reassemble the unit. 15:adjust the bias trimmer for best response. This is a subjective adjustment. I set up a good sounding non-inverted envelope with the filter cutoff around 5, flipped the invert switch, and adjusted the trimmer while playing until I got a reasonable sound. Play with it. Hints: I suggest using the shortest wires possible, my construction involved putting the 8 pin 741 IC into a 14 pin wire-wrap socket and soldering two of the unused pins of the socket to a big ground plane on the back of the board for a stable mounting point. I soldered the resistors onto the socket before mounting the socket. I drilled a hole near the cut trace in step 5 to run the f-mod and f-env signals to the inverter. Make sure you don't hit a trace on the other side of the board. The ground line is easy to find, all of the envelope pots have their metal cases soldered to it. To find the + and - 15V lines, carefully measure the voltages on the board near the power supply regulator section, look for the heat sinks until you find + and - 15V relative to ground. If that doesn't make sense to you, try tapping off of a known IC's supply pins, TL082 chips have -15 on pin 4 and +15 on pin 8. Parts are available from any reputable electronics store and Ratty-ol'-Hack stores as well. That's it, be careful, don't fry anything (including yourself). Nyooooweet Nyooooweet Nyoooweet... From jneedham@us.oracle.com Wed Jul 14 20:16:02 1993 Received: from gatekeeper.oracle.com by quark.magnus.acs.ohio-state.edu (5.65/3.910213) id AA11525; Wed, 14 Jul 93 20:15:56 -0400 Received: from hqpyr1.us.oracle.com by gatekeeper.oracle.com (5.59.11/37.7) id AA28659; Wed, 14 Jul 93 17:15:53 PDT Received: by hqpyr1.us.oracle.com (Oracle 1.12/37.7) id AA29889; Wed, 14 Jul 93 17:11:06 PDT Message-Id: <9307150011.AA29889@hqpyr1.us.oracle.com> Date: Wed, 14 Jul 93 17:11:06 PDT From: "jneedham.US" To: analogue-request@magnus.acs.ohio-state.edu Subject: Other Possible Pro-One Mods Original-To: HQPYR1:analogue-request@magnus.acs.ohio-state.edu Status: OR In-Reply-To: HQPYR1:analogue-request@magnus.acs.ohio-state.edu's message of 14-Jul-93 13:28 Some other mods that are quite easy to do on the Pro-One: LFO saw down selection Since there are spares (unused opamps on 14 pin ICs), inversion is a matter of just running wires. I did prototype this (take a close look for solder marks Brett) put pulled when I sold it. Daughterboarding in opamps is a more robust solution, just not as quick ;-) LFO retrigger mod Also getting the LFO to retrigger on keystrokes should also take a minimum of fiddling. Very useful as a third ENV (or ramp, I should say) See how SCI wires up SYNC between the CEM3320s for guidance. later,jeff ---- Included Message ---- Received: 07-14-93 13:28 Sent: 07-14-93 13:28 From: HQPYR1:analogue-request@magnus.acs.ohio-state.edu To: analogue@magnus.acs.ohio-state.edu Subject: Re: inverted filter envelope (Pro-One Mod) Reply-To: HQPYR1:analogue-request@magnus.acs.ohio-state.edu Errors-To: analogue-request@magnus.acs.ohio-state.edu Sender: analogue-request@magnus.acs.ohio-state.edu In-Reply-To: <9307141930.AA22823@stout.atd.ucar.EDU>; from "Forrest Cook" at Jul 14, 93 1:30 pm X-Mailer: ELM [version 2.3 PL5] Previously, Forrest Cook wrote: > > I finally got around to adding filter envelope inversion to my Pro-One synth, > I did it with one 741 op amp, 3 resistors, and 1 trimmer pot. If anyone is > interested, I'll hack together an asciimatic. I put a switch on the back > of the Pro-One that selects inverted or normal mode. Yup, I'd be interested, as I just got one of these critters about 3-4 weeks ago (no! I'm _not_ planning on getting rid of it! :>) and it'd be nice to have an invert mode for the EG output, if not just for the VCF EG, but for both EGs. I assume they're both the same circuitry... > > Speaking of the Pro-One, I noticed the circuit board had some interesting > things on it such as a silkscreened Buddah, some metal 'shrooms and flowers, > and a bunch of Sanskrit? writing. Anybody know the story behind that? Looks like it's time to get out the screwdriver...sounds worth investigating! D.A.C. Crowell Computer Music Project/School of Music University of Illinois at Urbana/Champaign (dacc@cmp-rt.music.uiuc.edu) PS...Forrest...I've been forgetting to get you the particulars on that piece for the analogue-heaven tape. I'll send those on eithe tonight or tomorrow. I _do_ need that original master DAT back now, btw...hope you got it copied. -- From analogue-request@magnus.acs.ohio-state.edu Wed Jul 21 13:02:16 1993 Received: by quark.magnus.acs.ohio-state.edu (5.65/3.910213) id AA24412; Wed, 21 Jul 93 12:58:23 -0400 Errors-To: analogue-request@magnus.acs.ohio-state.edu Sender: analogue-request@magnus.acs.ohio-state.edu Received: from ncar.ucar.edu by quark.magnus.acs.ohio-state.edu (5.65/3.910213) id AA24405; Wed, 21 Jul 93 12:58:21 -0400 Received: from stout.atd.ucar.edu by ncar.ucar.EDU (5.65/ NCAR Central Post Office 03/11/93) id AA11358; Wed, 21 Jul 93 10:58:19 MDT Message-Id: <9307211658.AA15871@stout.atd.ucar.EDU> Received: from bitter.atd.ucar.edu by stout.atd.ucar.EDU (5.65/ NCAR Mail Server 04/10/90) id AA15871; Wed, 21 Jul 93 10:58:18 MDT To: analogue@magnus.acs.ohio-state.edu Subject: Adding an insert to the Pro-One Date: Wed, 21 Jul 1993 10:58:17 -0600 From: Forrest Cook Status: OR Well, all of this talk about inserting effects into synths got me going AGAIN. This list sure is great for inspiring ideas. I put an insert jack in between the oscillators and the VCF/VCA on my trusty Pro-One. The back panel is starting to resemble shotgunned swiss cheese. (2 holes actually). The mod was trivial and the results are very interesting. I have only tried a phaser pedal which didn't like the levels and a fuzz box which sounded great. I still need to insert my Quadraverb in the chain. The fuzz gives a really nice metallic sound using the two oscillators, it sounds a bit like a smoothed out ring modulator. This mod is definitely good for fattening up the sound of the synth. I'm beginning to sound like a stereo salesman, say "delicate nuances"... The mod consists of cutting the line (lines actually) that go from the oscillators and noise source to the Curtiss 3320? VCF chip, pin 1. Leave the resistor that goes from pin 1 to pin 7 in place. I installed 3 wires from the board to the back of the unit, ground, send (from oscillators) and receive (to 3320 pin 1). The insert jack I used is a 1/4" stereo jack with switching on both tip and ring. The tip and ring SWITCH contacts are wired together so the signal can go straight through the jack when nothing is plugged in. The send line went to TIP and the receive comes from RING. That's how my Seck board is wired, so I adhered to their standard. The ground line goes to the SLEEVE contact (outside shell) of the jack. IMPORTANT: either use a plastic insulated jack or get some of those fiber washers with collars (or drill a big hole and mount a piece of plastic in it to hold the jack, DON'T ground the insert jack to the chassis or you will introduce a ground loop and HUMMMM. This is fairly tricky surgery, Don't attempt this unless you have some experience working on PC boards and dealing with sensitive electronics. Forrest Cook cook@stout.atd.ucar.edu WB0RIO {husc6|rutgers|ames|gatech}!ncar!stout!cook