Wednesday, December 16, 2020

synthesizers.com Q106A: LED behavior mod

The LED on synthesizers.com's Q106A oscillator cycles as a triangle wave regardless of the shape selected with its waveform selector switch. In LFO mode, I've often wished the LED would follow the shape of the waveform. When the LFO is very slow, it can be hard to tell when the waveform changes direction.

I've grown accustomed to how LEDs on Serge modules accurately track their "action", and it can be really helpful for certain things, especially when you're watching for that LED from across the room.

With the Q106A's LFO outputting square or pulse waves, for example, it'd be handy if the LED snapped on and off rather than slowly fading in and out. Or with a sawtooth wave selected, it'd be great if the LED snapped on with the saw's sharp rise and then slowly faded with the saw's descent. So I asked James at synthesizers.com if there's any circuitry on the Q106A that could be co-opted for this purpose.

James said he'd do some digging/experimentation and get back to me. I've not heard many anecdotes of synthesizers.com encouraging DIY work on their stuff, so I was surprised and delighted by his response. When James got back to me again a couple days later, he confirmed that "the PCB can be modified so that the selection on the Wave Range Switch drives the LED. So the LED will follow the [shape] of whatever waveform that switch is set to. Note that this is really only useful at low frequencies. Most of the time the LED will look the same."

He offered to draw up a how-to for me, which I enthusiastically accepted. He then sent this annotated picture which shows "the cut and re-route that needs to be done for the LED to respond to the selected waveform. In this case the LED will respond to the Waves Attenuator as well. If the attenuator is off (0) then the LED might be on or it might be off... It depends on the tolerances in one of the op-amps."

Having previously converted my Q106 oscillators to the Q106A flavor, I've been in the guts of these modules before and knew I was looking at labeling and disconnecting everything attached to the PCB in order to remove it. I used low-tack painter's tape to label each of the connectors so that the tape would be easy to remove.

With the PCB freed from the panel, a sharp knife made short work of the single trace that needed to be cut. For the solder work I used a PCB clamp to hold things steady and helping hands to position the piece of wire I'd be using to bridge the two connection points indicated in James' diagram.

Once the other end of the wire was soldered into place I confirmed continuity between the resistor leg and header pin (on the other side of the PCB) that corresponded to my new connection points. With that done, all that was left was reattaching everything.

With the right tools (namely the PCB holder and helping hands), the mod itself is a breeze, even for a novice solderer. The hardest part is having the patience to label the connectors before pulling it all apart.


This mod doesn't change the functionality of the oscillator in any way. It merely changes the LED behavior to provide better visual feedback when using the oscillator as an LFO. Within the "Waves" section of the module, the +/- outputs and the LED will follow the wave shape selected by the switch. And since the individual outputs at the bottom of the module are not connected to the wave selector switch, the patched output can be one shape while the LED displays another.

I've performed this mod on all of my Q106A oscillators. It feels like my 5U modular synth just got another really cool upgrade. Thank you, James and synthesizers.com!

Monday, August 24, 2020

Armchair Migraine Journey - Dying Time Machine

Available at long last: Dying Time Machine, featuring collaborations with Randall Frazier (Orbit Service), Scot Solida (Christus & The Cosmonaughts), Prajna, and Edward Ka-Spel (The Legendary Pink Dots).

DTM is an inspired and deeply personal album started nearly 5 years ago, set aside for a year and completed in 2017, and then set aside for another 3 years. We're proud to finally bring this one into the light.

1.  Rapture of Rupture:
AMJ - pulses, drones, modular, ipad
Randall Frazier - vocals, synths, loops
Ty Hodson - guitar, bass, drums
Edward Ka-Spel - lyrics, inspiration
Mixed by Ty Hodson

2.  Rupture of Rapture:
AMJ - bass, drones, modular, voice
Scot Solida - guitar, rhythms, hammond
Ty Hodson - drums, synths, bell
Prajna - vocals
Mixed by Scot Solida

Tuesday, October 2, 2018

New blog: Serge Modular Synthesizer Info

I've started up a new blog focused on the Serge modular music system. A labor of love, really, for information on the Serge has lately been scattered hither and yon. Some of the best info was in the SMOG and Quadslope forums, which evaporated years ago (there's still an active Buchla, EMS & Serge subforum at Muffwiggler). Happily, the Serge itself didn't go anywhere and has even cropped up in new and unforeseen places, including a vibrant DIY community.

Serge Tcherepnine's circuits are pretty legendary, and while some designs have changed over the last 40 years, much of the core stuff that makes the Serge system so great has remain unchanged — so much so that even most of the oldest catalog descriptions are still relevant.

And that's where my labor of love began: collecting those various catalog details into a single place, which ended up being a monstrous spreadsheet. I finally decided to migrate that info to a blog format, and then that awoke my hunger to have fresher, deeper information on the Serge. And here we are.

I've only begun writing up detailed walkthroughs of the Serge, with pretty oscilloscope images, patch tips with diagrams, and explanatory video demos. I also recently reconnected with cebec from those halcyon SMOG and Quadslope days, and he has graciously offered up his archive of patch suggestions & explanations from those groups for me to cull for future blogfodder.

Check it out here: https://sergemodularinfo.blogspot.com/


Friday, December 1, 2017

New gradenko album: NOVI NORI

I'm excited to announce the first gradenko album, available now at bandcamp. NOVI NORI, a love note to Krautrock, was recorded last winter and seems fitting to see release now with winter fast approaching.

Mastered by Randall Frazier (Helmet Room Recordings, Orbit Service), with artwork support provided by Chris McBeth (Beta-lactam Ring Records, Armchair Migraine Journey).


All songs written and performed by gradenko
Recorded Feb/Jun 2015 & Nov 2016-Feb 2017 at sublevel9 studios
Mixed and Produced by Ty Hodson
Mastered by Randall Frazier at Helmet Room

Ty: photography, design, layout
Chris: photo treatment

gradenko.bandcamp.com/album/novi-nori

Sunday, September 3, 2017

Don't give up on those old drum machines


I love old gear. But sometimes parts degrade or stop working and you wish you had a brilliant friend who knows how to find problems and fix them. As it happens, I have such a friend -- one Curtis Rochambeau of Rochambeau Musical Apparatus -- and was stoked when he agreed to come check out my ailing Korg SR-120 drum machine. It wasn't outputting any low end. So no bass drum and no tom sound.

My own suspicion was that some part involved in producing low end sounds was toast: besides there being no bass drum sound in each of the built-in patterns, there was also no bass drum or tom sound happening during fills invoked by the manual change button. Just silence during the hits that should have been there, while the crispy snare and hi-hat continued doing their jobs. But that was the extent of my ability to troubleshoot.

Consulting the service manual (thank you, internet), it was easy enough to spot sections of the circuit that performed certain functions. Well, I say "easy" because those sections were labeled with things like "B.D." (bass drum), "S.D." (snare drum), "Equalizer" and "Power Supply", and so on. But Curtis can look at those diagrams and understand that this chip is doing that, and this cap is needed here for this, and these 100 ohm resistors do that. He quickly identified where the triggers for the various sounds originated, so he used his probe to watch the oscilloscope for electrical triggers being sent from each pin on a particular chip. 

We could see a pretty obvious trigger coinciding with the snare sound, and we knew where the bass drum sound should have been occurring. So with the drum machine playing through the sound system we watched for triggers on the 'scope that happened where the bass drum should have been.


Once Curtis identified the pin for the bass drum trigger, he followed the trace on the circuit board to the point where the received trigger would hit the part responsible for producing the bass drum sound. Except that the trigger wasn't being seen on the other end. At this point Curtis declared, "This should be an easy fix."

He proceeded to flip the circuit board over and back, over and back, following circuit traces with his eyes and fingers, looking for possible reasons why the trigger signal wouldn't be making it to the next hop along the path. "Well, that's no good," he said, pointing to a spot of corrosion at one of the connection points. In fact, there were two or three other spots of corrosion around the board, and they all corresponded to capacitors. Ah, so that's why people have to re-cap old gear after a time...

Curtis scraped away the corrosion from our suspected trouble pin, saying that if the corrosion hadn't eaten away at the circuit trace itself, then he could simply re-solder that spot. As long as the electrical signal could pass that spot, we should see the bass drum trigger downstream. So he gave that a try. Alas, the signal did not pass. He then reluctantly tried to finesse some solder before and after the pin to try to bridge the gap, but that didn't work either. So he undid that, and said, "We could just bypass this cap altogether, and then someday when you re-cap this thing, you can remove the bypass and put the new cap back in play (assuming the trace isn't corroded too)."

He probably explained why we could bypass this particular capacitor, but my arms were getting tired from holding a light for him and my beer was out of reach for the moment. OK, Curtis, so what do we use to bypass the cap? "Just a little wire." Well, since we're ad-libbing here, do I have something lying around the house that could do the trick? "Do you have some CAT-5 network cable? We could steal a wire out of that."

Blip. Blip. That's the sound you make when you just soldered two points, connecting a little wire from point A to point B, bypassing a bad cap. In this photo, the small orange wire is our bypass, and you can see the corrosion at the point where the bypass wire bends to the left.

We flipped the whole thing over and fired it up. BOOM.... BOOM BOOM... BOOM... BOOM BOOM... We have bass drum!

Thinking about it later, I asked Curtis to explain to me again how he knew he could just bypass that capacitor. He wrote back:

"Most big caps you see are just doing power supply decoupling, so any noise or cycled waveform created by an adjacent circuit does not bleed through the power rails and affect other circuits. They perform this function because they pass AC (signal and noise) while blocking DC, so you strap a cap from the power rail to ground in hopes of limiting the available voltage to just DC. Those 100 ohm resistors separating sections in the power rails provide a small enough "incline" that spurious signal has an easier path through the cap, so it doesn't wander and bother the neighboring sections, so to speak.

"So that cap’s only function is to sluice any noise (or signal, because when a section is generating a wave form it pulls power in a way that reflects the waveform onto the power rail) originating at the bass drum and tom section from rippling out and affecting other sections. But we're dealing with small signals here, not power amp level draw, so the likelihood of the bass drum modulating other sections is minimal - because in order to do so, it would have to pass through the localized filtering supporting the neighboring sections as well. It's kind of a redundant system. Plus, we only know that the power rail was severed at the cap, IF one leg of the power rail is still attached to the cap, the cap is effectively still in circuit after bridging the severed trace. I didn't have tools to measure that on hand, and at the end of day, it sounds awesome - so even if the bass drum is pummeling other sections when it hits, it does so in a musically valid way.

"The caps that really affect the sound of something are either interstage DC blockers (when they leak everything sounds worse), or a tuning/timing constant on an oscillator or filter, but those are rarely electrolytics, and enjoy a much longer lifespan."

Thursday, September 8, 2016

square_wave / Prajna - Inside Suns, Perfect Gaze


BlRR Recommended. Edition of 250 copies with the first 100 numbered.

Available Sep 15. Split release by square_wave / Prajna. Two long lovely, floating tracks.

1.  square_wave - Lovers Slumber  (21:59)
Ty Hodson - monome, estate sale records, synths, percussion, vocals, mix
Prajna - supine presence, rummaging
Drifting through mists hanging heavily on forests coming to life under sun-kissed clouds, playful Oni lure lost children. 

2.  Prajna - Want to Need  (20:34)
Prajna - bowed and tapped violin, gas tank bells, vocals, processing, mix
Ty Hodson - field recording, processing, mix
Slipping like ghosts through thousand-year-old monastery walls, crossing hidden courtyards where Buddhist monks make their cell phone calls.

Ty Hodson has released music under the square_wave moniker since 2007, having released four albums on his sublevel9 studios imprint. On the side, he writes and records under the name gradenko, with a post-rock/prog album slated for future release on Beta-lactam Ring Records. Ty also represents one half of Armchair Migraine Journey.

Prajna has appeared previously on Armchair Migraine Journey’s ‘Blood Coupling Magnet’ on vocals alongside Soriah. "Want to Need" is her first published solo work.

Mastered by Randall Frazier at Helmet Room
Chris: artwork, design, layout

Edward Ka-Spel / Armchair Migraine Journey - Transmit Acoustique Abstraction Three



Issued Sept 15th to coincide with the N. American tour of The Legendary Pink Dots and Orbit Service. An edition of 111 copies available on the tour with 39 copies available via the label mail-order (first edition of 150). Packaged in a French Black six panel CD case. Two years in the works and finally seeing the light of day. 

“Infernal Machine” a collaboration with Edward Ka-Spel and Armchair Migraine Journey delves deep into a psychedelic swirl of sounds. 

“Strands That Bind”, a new track by AMJ dives slowly into a sea of ambient drones and passages and develops along its 24-minute journey into an almost metal machine music dirge. 

1. Edward Ka-Spel / Infernal Machine: 
Edward Ka-Spel - vocals, synth noodling 
AMJ - drones, synths, processing 
Ty Hodson - drums, vocoder, processing 
Mixed by AMJ and Ty Hodson

2. Armchair Migraine Journey / Strands That Bind: 
Ty Hodson - guitar, drums, synths, processing 
AMJ - synths, drones, theremin 
Randall Frazier - The Voice of …? 
Mixed by AMJ and Ty Hodson 
Includes deconstructed elements of ‘Magnetic Blood Drowning’ with Peat Bog (Earthmonkey) and Randall Frazier (Orbit Service)

'Infernal Machine' by Edward Ka-Spel, AMJ, Ty Hodson 
'Strands That Bind' by Ty Hodson, AMJ
Mastered by Randall Frazier at Helmet Room