Hello all,
I hope this is the right place to post this.
When I first started this project I could never find a demo, and I saw a number of people mentioning it here and asking about samples/demos.
Well I built it (on faith / blind hope) and it works! I kind of love it, for all it's cheesy, retro, glitchy, glory. And here's a demo!
I didn't say it was a
great demo did I?!
Anyway, the 'mini synth' was a project (#10) in
Funway Into Electronics 3 published by Dick Smith in 1983, four years before I was born! It was intended to be used with a microphone, but it works surprisingly well with an electric guitar!
I've just discovered that http://www.funwayelectronics.com (http://www.funwayelectronics.com) is now the public face of Funway Into Electronics. The site looks like it's been abandoned since 2016 unfortunately. However they do mention 'the intent of bringing the material back into the public domain', which would suggest the various book scans floating around the net possibly can be downloaded legally. Maybe?
There are scans of all three Funway books on the Internet Archive:
https://archive.org/details/funway_into_electronics/funway_into_electronics_vol_3_17th_printing/page/n81/mode/2up
Or just the mini synth project on General Guitar Gadgets, which is probably how most people here will have come across it. I actually think the above archive version/s might be clearer, but anyway, this is the GGG scan:
http://www.generalguitargadgets.com/how-to-build-it/technical-help/articles/mini-synth/ (http://www.generalguitargadgets.com/how-to-build-it/technical-help/articles/mini-synth/).
Originally you were able to get a printed/etched circuit board, but since these appear to be no longer in production I made it on 'perfboard', wiring each individual connection!
I'm amazed it worked to be honest! So many opportunities for mistakes!
In the book it's described as follows:
"This musical-based circuit is the most complex in the book, but it's a load of fun. By using a microphone sound detecting input, a whistle, hum or voice can be the note generator. In this way, you can be your own oneman-band (sorry, girls: one-personband) without being able to read a musical note! Based on a Phaselocked-loop (PLl.) design, the circuit 'reads' the incoming note frequency and I holds' it until the next input signal. This note is available at the output of two channels determined by an adjustable decay circuit Tremolo can be added as a further extension of the basic note which, incidentally, can also be halved or doubled in frequency to give a multitude of different sounds."
stylophone! gets my vote. I like the octave hopping. welcome to the forum.
all the kids will be wanting to see the/your perf layout, and gut shots. Dick has gone, now, closed all his shops a while back.
welcome to the forum,
despite the hiss, that's a nice demo.
i don't believe the PLL can go out of tune, considering that it has feedback to match the output frequency with the input freq.
i like the broken, glitchy nature of the pedal, and if i were to build something similar, i'd add deliberate glitches and problems in the feedback loop to degrade the tracking.
cheers
hi and welcome...very cool.
is it more stable with a compressor in front?.
Welcome!
That is pretty bonkers. Like it.
It *really* makes me want to add an envelope-follower and filter to it, for extra synthiness. And then maybe stick a StompLFO in it too, and..and..and!! ;)
But a filter would be an excellent addition. With those buzzy waveforms, you'd be in guitar-playable monosynth territory in a big way.
Looking at the schematic, there are a number of possibilities immediately evident. First, the two "channels" deserve a simple mixer so that they can be blended into a single voice. The schematic shows that the LFO (IC1D) feeds them individually, such that one channel can be modulated while the other remains "pitch-stable". Having individual decay controls for each voice, when they are blended, is also a nice feature. Presumably, the pitch of one of the voices could be changed to a 5th above or below, but would require changing to a different CMOS divider chip other than the 4013 flip-flop. That is certainly feasible, but I think many would prefer what can be done with as little changes to the original layout as possible. However, if one perfs it, as you did, then I gather a 4017 or 4024 would be called for.
I gather C11 can be increased to slow down the modulation rate below its stock range. And if the pitch of the 4046 VCO is being modulated, then taming that modulation amount might be a good thing.
Did you change anything to use it with a guitar, or was the Mic Input Level control sufficient for tracking purposes?
(http://www.generalguitargadgets.com/wp-content/uploads/msynth4.jpg)
Quote from: duck_arse on February 28, 2021, 07:57:18 AM
stylophone! gets my vote. I like the octave hopping. welcome to the forum.
all the kids will be wanting to see the/your perf layout, and gut shots. Dick has gone, now, closed all his shops a while back.
Haha I suppose it does sound a little like those! Thank you!
As far as the perf layout goes, I just printed out two copies of the original layout (flipping it for the underside) and lined them up with the holes as best I could. Then I wired following where the traces would have been! It maybe wasn't the best way of doing it, I don't know, but it gave me a clear guide for each connection and helped me keep track of what I'd done as I slowly worked on it. I've cut some areas away, but you get the idea.
(https://i.postimg.cc/V5N26GvQ/IMG-7660-2.jpg) (https://postimg.cc/V5N26GvQ)
Yes, sadly I believe you're right about the physical stores, although there does seem to be an online store still.
Thanks again!
Quote from: iainpunk on February 28, 2021, 08:53:36 AM
welcome to the forum,
despite the hiss, that's a nice demo.
i don't believe the PLL can go out of tune, considering that it has feedback to match the output frequency with the input freq.
i like the broken, glitchy nature of the pedal, and if i were to build something similar, i'd add deliberate glitches and problems in the feedback loop to degrade the tracking.
cheers
Thank you!
Ssorry about the hiss, I couldn't get my video editor to eliminate that, and didn't have time (and I was lazy!) to extract the audio and fix it properly. Anyway thanks!
Yeah, I think it's more that it isn't matching the output frequency correctly, so everything is shifted slightly. Maybe?!
Haha each very much to their own, but I'm glad you like it! Maybe you could have a switch, or even a knobe that would dial up the clitchyness.
Thanks again!
Quote from: deadastronaut on February 28, 2021, 09:14:10 AM
hi and welcome...very cool.
is it more stable with a compressor in front?.
Thank you, thank you!
Oh I'm not sure, I'll have to try at some point! I think it would need more some kind of filter or tone control to minimize sub-harmonics, but still worth a try.
Thanks again!
Quote from: ElectricDruid on February 28, 2021, 10:12:23 AM
Welcome!
That is pretty bonkers. Like it.
It *really* makes me want to add an envelope-follower and filter to it, for extra synthiness. And then maybe stick a StompLFO in it too, and..and..and!! ;)
But a filter would be an excellent addition. With those buzzy waveforms, you'd be in guitar-playable monosynth territory in a big way.
Thanks!
Yeah, it is! Thank you, I'm glad you do!
Haha so many possibilities! I've been thinking about making a filter pedal/box actually, and you're right that would probably go really well with this.
Thanks again!
Quote from: Mark Hammer on February 28, 2021, 12:31:08 PM
Looking at the schematic, there are a number of possibilities immediately evident. First, the two "channels" deserve a simple mixer so that they can be blended into a single voice. The schematic shows that the LFO (IC1D) feeds them individually, such that one channel can be modulated while the other remains "pitch-stable". Having individual decay controls for each voice, when they are blended, is also a nice feature. Presumably, the pitch of one of the voices could be changed to a 5th above or below, but would require changing to a different CMOS divider chip other than the 4013 flip-flop. That is certainly feasible, but I think many would prefer what can be done with as little changes to the original layout as possible. However, if one perfs it, as you did, then I gather a 4017 or 4024 would be called for.
I gather C11 can be increased to slow down the modulation rate below its stock range. And if the pitch of the 4046 VCO is being modulated, then taming that modulation amount might be a good thing.
Did you change anything to use it with a guitar, or was the Mic Input Level control sufficient for tracking purposes?
Yes, I would have liked to have done some kind of blend option for a single output. However having them separate does allow for a cool stereo effect!
And I'm sure you're right about the '5th above or below' change, which would be a really cool feature to see someone do (someone with more understanding than me!)
Oh yes, I'd forgotten about the C11! I think I intended to socket it, to allow some experimentation, but completely forgot when I was putting it together. I guess you could have a switch to allow changing between different ranges which would be quite cool. Or maybe you'd just change the pot to suit the new range?
No I didn't change anything. I was expecting I might have to do some troubleshooting, but it just worked!
Thanks again!
I have been spending the "better" part of the day digitally editing the parts layout diagram in the Funway book to remove all the parts numbers and other stuff, in order to leave the basic PCB pattern. I hope to have it finished and posted here tomorrow.
PLEASE tell me such a PCB pattern, suitable for toner transfer does not currently exist out there.
Quote from: Mark Hammer on February 28, 2021, 08:21:06 PM
I have been spending the "better" part of the day digitally editing the parts layout diagram in the Funway book to remove all the parts numbers and other stuff, in order to leave the basic PCB pattern. I hope to have it finished and posted here tomorrow.
PLEASE tell me such a PCB pattern, suitable for toner transfer does not currently exist out there.
Oh wow, that's quite the job to take on! Originally I wondered if one of PCB layout programs might let you 'draw' over an image using it as a guide, to get a really nice clean vector pattern for toner transfer, or even cnc, but didn't end up bothering since I ruled out making my own board.
No, I couldn't find any such PCB pattern, so pretty sure your efforts are definitely not wasted!
Good. My efforts will not be wasted. I can sleep soundly tonight.
Cool... :icon_eek:
Welcome to the forum too.. ;)
Using the 4046 phase pulse detector at pin1 to make the envelope for the VCA is cool. Not seen that before.
Quote from: TFJames on February 28, 2021, 09:28:29 PM
Originally I wondered if one of PCB layout programs might let you 'draw' over an image using it as a guide
I know there's one that do this, but didn't bothered too much to learn how to use it. But anyway, people who are used to work with some image editing software (corel, photoshop) may prefer to just use the one they already know how to work with.
Very nice demo, it shows lots of possibilities this one can do. I really liked how it sounds, and may be building one in the future. Thanks for the demo.
Just out of curiosity, have you tried it with a mic? It may be fun.
Quote from: anotherjim on March 01, 2021, 05:47:52 AM
Using the 4046 phase pulse detector at pin1 to make the envelope for the VCA is cool. Not seen that before.
Yeah, I liked that too. It's kind-of a variation on the Roland "swing type" VCA, where you use a pulse waveform to switch a voltage on and off, rather than changing the actual volume of the pulses with a proper VCA. The CV feedthrough is bad because the resulting waveform is unipolar, but it's cheap and simple.
Not to go off on a tangent, but doesn't Illustrator allow you to import an image, and then add a 'layer' over it where you can do the tracing, without messing up the original?
Quote from: rutabaga bob on March 01, 2021, 09:59:20 AM
Not to go off on a tangent, but doesn't Illustrator allow you to import an image, and then add a 'layer' over it where you can do the tracing, without messing up the original?
Pretty much any graphics package beyond MS Paint allows you to do that, so yes.
The challenge with this, as I am finding out (and almost done, thank goodness) is that the original illustration and legending obscures the connections between pads. The redrawer has to keep referring back to the original and the schematic, in order to discern what truly IS a connection/trace, and what is merely a visual artifact that LOOKS like a trace. The source of the problem lies in the scan of the original, which seems to have introduced some artifacts. I know it may look like black legending on top of a red PCB lattern, but the legending itself produces a kind of red "halo".
I certainly wish it was easier, but as Moe Szyslak says: "If wishes were horses I'd be eating wish meat every night".
Quote from: ElectricDruid on March 01, 2021, 11:47:27 AM
Quote from: rutabaga bob on March 01, 2021, 09:59:20 AM
Not to go off on a tangent, but doesn't Illustrator allow you to import an image, and then add a 'layer' over it where you can do the tracing, without messing up the original?
Pretty much any graphics package beyond MS Paint allows you to do that, so yes.
some guys on Discord started doing a MS Paint clone that can toggle the ''transparent colour'' to be transparent and show another image through the one you work on. you can then change the transparent colour to show different parts of the image 'behind' your work piece.
i haven't seen any updates on that project since 2017, so i guess they abandoned it.
cheers
Okay, here we go. It is perhaps not as smooth as it might be at a higher resolution, but then the original was not exactly hi-res itself. I cannot vouch for the pin spacing. If you use it to make your own PCB, you'll likely have to do a few dry runs at different scales on paper, until you find the right size, before committing to a toner transfer. Feel free to edit whatever strikes you as too ragged. Because the original was shown from the component side, looking "through" the board, there is no need to flip the image for use with toner transfer.
(Addendum: I found that if I printed it out at 19% size, it came out just right)
Enjoy.
(https://i.postimg.cc/TyJWCHRF/minisynth-board.png) (https://postimg.cc/TyJWCHRF)
Quote from: Marcos - Munky on March 01, 2021, 07:02:47 AM
Just out of curiosity, have you tried it with a mic? It may be fun.
I might be wrong in my interpretation, but given that the input gets amplified and then sent straight into a schmitt trigger, it wouldn't retain any of the qualities of a human voice (vowels, consonants, etc). And the dynamics of the human voice would make triggering unreliable. I would think that guitar should work better than voice, even better if boosted first, and a keyboard should work better than a guitar.
This reminds me a lot of Freppo's CMOS inventions. I can get consecutive hours of enjoyment making noises with something like this.
Quote from: Marcos - Munky on March 01, 2021, 07:02:47 AM
Quote from: TFJames on February 28, 2021, 09:28:29 PM
Originally I wondered if one of PCB layout programs might let you 'draw' over an image using it as a guide
I know there's one that do this, but didn't bothered too much to learn how to use it. But anyway, people who are used to work with some image editing software (corel, photoshop) may prefer to just use the one they already know how to work with.
Very nice demo, it shows lots of possibilities this one can do. I really liked how it sounds, and may be building one in the future. Thanks for the demo.
Just out of curiosity, have you tried it with a mic? It may be fun.
Yeah, I've been using Photoshop for years, but always found it's vector and/or curved line capabilities a bit limited. However, how embarrassing, I've just checked and worked out you can actually use 'paths' in ways I hadn't realized before, which will be very helpful in future! Thanks for inadvertently making me discover that haha!
Anyway my reason for maybe wanting to use a proper PCB layout tool was just that they would allow better editing of groups of traces, keeping everything connected if you wanted to shift the layout around, and also highlighting everything that's connected to each other, so one might better understand the circuit. And then the big thing, I thought, would be outputting in the right format for any of the ways you might make a board or have it made commercially. But yes, learning the program probably wouldn't be worth it for a one off like this.
And thank you! Glad you like it, and found it inspiring! Hope you have a go, it's a pretty fun effect.
Yes, I did try it with a mic when I first turned it on, but didn't really play with it much because I was bounding away to grab my guitar! I vaguely remember it being okay-ish, but I think Radical CJ is probably more or less correct:
Quote from: Radical CJ on March 01, 2021, 05:06:44 PM
Quote from: Marcos - Munky on March 01, 2021, 07:02:47 AM
Just out of curiosity, have you tried it with a mic? It may be fun.
I might be wrong in my interpretation, but given that the input gets amplified and then sent straight into a schmitt trigger, it wouldn't retain any of the qualities of a human voice (vowels, consonants, etc). And the dynamics of the human voice would make triggering unreliable. I would think that guitar should work better than voice, even better if boosted first, and a keyboard should work better than a guitar.
This reminds me a lot of Freppo's CMOS inventions. I can get consecutive hours of enjoyment making noises with something like this.
Also I haven't come across Freppo's CMOS inventions, will have to check them out!
Quote from: Mark Hammer on March 01, 2021, 02:03:21 PM
Okay, here we go. It is perhaps not as smooth as it might be at a higher resolution, but then the original was not exactly hi-res itself. I cannot vouch for the pin spacing. If you use it to make your own PCB, you'll likely have to do a few dry runs at different scales on paper, until you find the right size, before committing to a toner transfer. Feel free to edit whatever strikes you as too ragged. Because the original was shown from the component side, looking "through" the board, there is no need to flip the image for use with toner transfer.
(Addendum: I found that if I printed it out at 19% size, it came out just right)
Enjoy.
(https://i.postimg.cc/TyJWCHRF/minisynth-board.png) (https://postimg.cc/TyJWCHRF)
That's awesome Mark! Well done! I just remembered I did some arbitrarily colour coded versions I made to help get my head around the connections required (and to work out the issue you mentioned with the obscured connections) which may have been helpful. Sorry I didn't think of it before!!
(https://i.postimg.cc/WhQF7M2Y/mini-synth-circuitboard-colour-coded-01.jpg) (https://postimg.cc/WhQF7M2Y)
(https://i.postimg.cc/kDHBnxtM/mini-synth-circuitboard-colour-coded-02.jpg) (https://postimg.cc/kDHBnxtM)
Etched. Drilling and stuffing to follow tomorrow. The holes in the middle of the pads may or may not be a little too big, but I'll find out tomorrow.
(https://i.postimg.cc/9rxmXMTN/100-8861.jpg) (https://postimg.cc/9rxmXMTN)
Quote from: Mark Hammer on March 01, 2021, 07:01:34 PM
Etched. Drilling and stuffing to follow tomorrow. The holes in the middle of the pads may or may not be a little too big, but I'll find out tomorrow.
(https://i.postimg.cc/9rxmXMTN/100-8861.jpg) (https://postimg.cc/9rxmXMTN)
Woah MH, that was very fast... :icon_eek: most of the time I just procrastinate my builds... should clearly stop doing that... lol
Quote from: TFJames on March 01, 2021, 05:38:21 PM
Quote from: Radical CJ on March 01, 2021, 05:06:44 PM
This reminds me a lot of Freppo's CMOS inventions. I can get consecutive hours of enjoyment making noises with something like this.
Also I haven't come across Freppo's CMOS inventions, will have to check them out!
Yup, Freppo's website is https://www.parasitstudio.se, lots of cool stuff in there..
Quote from: 11-90-an on March 01, 2021, 09:25:10 PM
Woah MH, that was very fast... :icon_eek: most of the time I just procrastinate my builds... should clearly stop doing that... lol
We'll see how fast, tomorrow. Temperature's supposed to drop, and the garage (where the drill press is) may be uncomfortable to work in. Fingers crossed.
Quote from: Mark Hammer on March 01, 2021, 09:37:45 PM
the garage (where the drill press is) may be uncomfortable to work in.
That's "Canadian uncomfortable" he's talking about, which is probably about -15C in terms the rest of us understand! ;)
Well, it was that low earlier in the day, but with the midday sun we're up to a balmy -8C, so the drilling got done, and I'm stuffing the board now.
Actually, that color-coded image you posted, Tobias, is coming in handy. I appears that whoever scanned the Dick Smith book had built the Minisynth, and put a stroke through each component in the parts layout as they were installed, making the information hard to read. So thanks!
What I'm looking forward to is using it with my EHX Attack Decay pedal, which will impose an amplitude envelope on the resulting sound, to make it more like a guitar synth, and make the glitchiness less evident.
Quote from: Mark Hammer on March 02, 2021, 03:00:19 PM
Well, it was that low earlier in the day, but with the midday sun we're up to a balmy -8C, so the drilling got done, and I'm stuffing the board now.
Actually, that color-coded image you posted, Tobias, is coming in handy. I appears that whoever scanned the Dick Smith book had built the Minisynth, and put a stroke through each component in the parts layout as they were installed, making the information hard to read. So thanks!
What I'm looking forward to is using it with my EHX Attack Decay pedal, which will impose an amplitude envelope on the resulting sound, to make it more like a guitar synth, and make the glitchiness less evident.
Gosh, it doesn't half get brisk up there!
Oh great, my pleasure, I'm glad it came in handy!
That would be interesting! I was wanting to build/procure some kind of ADSR pedal a while back, maybe I need to look at that again. Look forward to hearing how you get on!
The Attack Decay is a woefully overlooked pedal, in my view. It's digital, so it does a much better job of tracking note onset, and also allows one to insert other effects in a loop and process them, using the envelope of the clean input signal. It's not marketed as a guitar synth pedal, because it doesn't do the fancy stuff of the explicitly synth pedals, but if you feed it an interesting signal it can serve up sounds indistinguishable from synths. Perhaps just as important - although that won't apply with the monophonic Minisynth - it is able to map modified envelopes onto notes polyphonically. That is, feed it a cascade of notes, and each will have its own separate rise and fall.
[ot]
Quote from: Mark Hammer on March 02, 2021, 03:00:19 PM
Well, it was that low earlier in the day, but with the midday sun we're up to a balmy -8C, so the drilling got done, and I'm stuffing the board now.
We once recieved a visitor from Canada once, nice chap, he said that the summer temperatures there are around 6-7C! Which is very, very different than our Philippine Summer 36-40C... ::)
Amazingly he wasn't a complainer and took the heat really well...
[/ot]
So, planning out some mods.
1) An added mixer stage, for combining the two channels into one.
2) An envelope follower, driving a bandpass filter which is fed by the mixer output. I'm thinking fed from the output of of IC1A.
3) Fast/slow range toggle for the tremolo.
4) Instead of two switches for individual tremolo, a single master 3-way switch for none, channel 1 only, or both.
5) A normal/mild switch for tremolo, which I *think* will involves changing the value of R35/R36.
6) I was thinking of putting the various octave up/down options on a 6-position rotary switch instead of two DPDT toggles, but I have to work out what such a switch could give me before committing.
The whole thing seems to be amenable to the 1590XXLG enclosure I had sitting around. This could be fun.
6-7C in the summer? Pish posh. We get plenty of days in the mid-30s. I like to tell people that the city of Calgary is "the future of weather". Absolutely no respect for the seasons there. People can be snowboarding in shorts and bikini tops in February, shovelling their driveways in August, and praying for a white Christmas as they mow the grass in November.
Finally fired it up. Interesting how the comparator aspect means you don't hear anything until you exceed the threshold. The sustain is worthy of Robert Fripp. But I don't seem to hear the PLLs. The pads on the board layout suggest the 3-position slide switches are not especially standard. What did you use on your build?
By the way, I have to compliment you on your build. I didn't quite realize it at first, thinking that it was a kit, but clearly you did the thing from scratch, so hats off.
For my part, I'm going to have to go over the board tomorrow to see where I've gone wrong.
Quote from: Mark Hammer on March 05, 2021, 09:01:36 PM
Finally fired it up. Interesting how the comparator aspect means you don't hear anything until you exceed the threshold. The sustain is worthy of Robert Fripp. But I don't seem to hear the PLLs. The pads on the board layout suggest the 3-position slide switches are not especially standard. What did you use on your build?
By the way, I have to compliment you on your build. I didn't quite realize it at first, thinking that it was a kit, but clearly you did the thing from scratch, so hats off.
For my part, I'm going to have to go over the board tomorrow to see where I've gone wrong.
Yes, I thought that was an interesting/good feature! And the sustain is surprisingly good too!
But oh no, problem! Yeah I originally bought the wrong sort and ended up paying a stupid amount to quickly get the unusual ones. The ones I used are Devlin SS-23F02-L7 from RS: https://americas.rsdelivers.com/product/devlin/ss-23f02-l7/panel-mount-slide-switch-dp3t-500-ma-50-v-slide/8290611
I'm not sure now whether the single pins connect to the three opposite them, or the three in line with them, but I'm leaning toward the first.
Oh thanks so much! Yes, I came across scans of the project and thought it sounded interesting, so slowly collected the parts and put it together. Thanks again, I appreciate it!
Good luck!!
I think they are 3 throw switches and the only alternatives are the similar toggle lever action (same slide mechanism pinout under) which will mean panel legends needs reversing or a 2 pole rotary switch set for 3 throws which would be easier to make wired off-board.
The intended style are rarely stocked, but still made and can be found from Asian vendors like Ali-express. Some vintage instrument spares suppliers carry them as Roland once used them a lot but these sources are expensive.
I don't remember what the subject was, but we have talked about this kind of switches before (may have been a Hens Teeth/DeadendFX subject).
I've a suspicion the pinout was not the expected with the common pin out on its own.
Note that on the schematic, the 2 switch poles are wired opposite ways so as you look at it, if the top left pin is made to its common pin, then the lower right pin is made to it's common pin.
Should be possible to confirm with DMM resistance/continuity beep which contacts are which.
If the project doc doesn't explain fully...
4046 pin 4 connected to pin 3, output from pin 4 = original pitch
4046 pin 4 connected to pin 3, output from 4013 Q pin = octave down
4046 pin 3 connected to 4013 Q pin, output from 4046 pin 4 = octave up.
I have one of the original DSE bought switches here [they were real cheep], it is stamped stylised PIC. contact pattern is
A1 A2 A3 Bcom
| |
Acom B1 B2 B3
pin spacing is a lttle over 0.1", such that the 6 pins cover 7 x 0.1 grid.
MANY thanks for that! Looking at the PCB layout, I now realize that the principle reason my unit was not working properly is because I was treating the pinouts on the board as corresponding to a more typical toggle. So far, I've now got the tremolo working, although the monophonic part still eludes me. Hopefully later today.
Had another thought about the switches. The original idea must have switches with contacts for all 3 throws. A DPDT on-off-on won't do it.
But looking at the connection choices...
4046 pin 3 connects from only 2 places. It's pin 4 (VCO out) or a flip-flop Q output.
Audio output comes from only 2 places. 4046 pin4 or a Q output.
... so you could use a pair of SPDT switches. 2 of the 4 possible combinations will be the same, but you still get the original 3 selections.
There are a few more sound sources that are being unused.
The 4046 phase comparator output on pin 2 will have a signal. It won't always be a square wave unlike all the others and is more like an XOR frequency doubler.
The pin1 phase detector pulses have a glitchy character of their own.
The VCO CV input can be used for a VCF CV source. The chip has a source follower buffer from pin10 to tap the CV from.
The Envelope for the VCA transistor could also be used as a VCF CV, although you may need to buffer/amplify that.