Tubes give synths a more organic and 3-dimensional sound, not so dry and in your face. And they let you adjust the tonality subtly, without using EQ.

Recently I made some changes to the tubes in a matched pair of Pendulum Audio Quartets that I use for tracking. The Quartet is a channel strip with three independent tube stages: a preamp, 3-band eq, and opto compressor. 

Pendulum Audio Quartets

Previously I had a pair of vintage Mullards in preamp sections—great for low-mid warmth, a smooth top end, and vibe...but are sometimes a bit dark. So I switched to a RCA Short Gray Plate in one of the preamps—mid-range focused, punchy, with a touch of upper-mid crispness. Sounds neat when overdriven, sort of 1950s-ish. Note these are different from the RCA Long Gray Plate which is a fuller and mellower sound (more low-mids), I have one of these too, but prefer it in the LA2A for giving tone to leads.

I still have early 50s Telefunkens in the EQ and compressor sections—clean, detailed top end, nice low extension, slightly pulled back midrange. So now I can switch between a rich low-mid mullard sound, punchy upper-mid RCA, or bypass the pre section for the clean telefunken sound. And it's still possible to get matched stereo by bypassing the pre section. Lots of options when tracking. 

By the way, Christian Whitmore of Pro Audio Tubes is a serious tube-geek who knows every tube that has ever existed, makes great recommendations based on what you’re after, and tracks down pristine specimens.


The FabFilter Pro-L version 2 is sounding even clearer than the original, which was already transparent. Here's the most invisible operating mode I've found so far...

Clipper Trick:

  • Modern algorithm

  • 1ms lookahead

  • attack max (removes this control from use)

  • 0ms release

  • left/right operation unlinked

  • No oversampling

  • Ceiling -0.2db (so it doesn't clip when converted to MP3)

  • Just clip occasional peaks by 1db

Clipper mode settings

Clipper mode removes unnecessary complexity. The limiter just ramps up fast, clips whichever channel peaked, and gets out of the way. No two stage release ("attack" and "release" are actually both release controls, which is confusing). No oversampling, which seems to kill the vibe. No stereo linking. Minimalist. When you engage the audition button (difference between the input minus output) you should hear silence, just an occasional "pop" in one or both speakers as the limiter briefly flicks on. I confirmed that this algorithm is doing nothing while audio is below the limiter's threshold by using SpetraFoo's transfer function; both frequency and phase are flat across the audio spectrum.

From here you can increase the lookahead to avoid harmonic distortion, 3-5ms gives a less crispy high end when the limiter pops. And you can also mess with increasing the release for a less punchy sound, that blends with the track's tempo. 

Clipping an occasional peak actually seems more “hi-fi” to me than a bunch of attack/release pumping.

Note there is a preset called "almost clipping" which uses similar settings, but the "aggressive" algorithm. To me this sounds less transparent than "modern", but might be useful for more aggressive-style electronic music.



1973, analog voices

Voices (10): bass drum, high conga, low bongo, high bongo, rim shot, cow bell, clave, cymbal, high hat, snare.

Patterns (27): each with A and B variation. "Auto" mode alternates between variation A and variation B. You can press multiple pattern buttons at once to combine rhythms.

Sound: round and warm. Think lounge, not aggressive electronic dance music. The TR-66 is not "angular and tight" like the snappy CR-78, it's softer. The kick is a winner, mellow but with a cleanly defined thump at 60Hz (decay is tunable via an internal trimmer, but not the pitch). The high conga, low bongo, and high bongo are recognizable classics (both decay and pitch are tunable via internal trimmers). The rim, clave, and cow bell are all tight and highly usable (they take reverb well). The snare is fine but can be a bit crude, but good if you get a nice sample (amount of white noise adjustable via internal trimmer). The hat and cymbal can get trashy (see "rock" rhythms), but nice if you get a tight sample, processes it, and use sparingly in the mix. The top end on this unit extends beyond 40kHh.

Balance knob: adjusts the relative levels of the kick and hat/cymbal (it’s not an EQ tone knob), while holding the midrange sounds constant. So if you turn counterclockwise you get more kick and less annoying hat. Around 9-10 o'clock is a balanced sound between the kick/hat, that's pretty much the usable range of this knob. Note you can not get isolated hits this way, as the hat/cymbal will not mute.

In/Outs: low impedance out (10k Ω), high impedance out (100k Ω, lower-gain output). There is also a “start” input for connecting a foot switch.

Notable use: Dust Brothers Fight Club score "Corporate World." Roxy Music "Dance Away."

Original documentsTR-66 Player's Manual (PDF)TR-66 Service Notes (PDF)


These rhythms were sampled 24/44.1k into a Metric Halo LIO8 using its DI input, then converted to MP3 320. No effects, just the dry rhythm box. Tuned using just intonation: bass drum 1/1, snare fundamental 9/8, high conga 5/3, low bongo 5/3, high bongo 9/8.


The 1973 service manual can be a bit hard to decipher, here is how you trigger individual sounds for creating your own samples. First remove the four screws on the base. The TR-66 will then slide out the rear of the wood case.

TR-66 with wooden case removed.

TR-66 sound generation board

Conveniently located on top you will see the Sound Generator Board. There is a cut out section in the metal platform on which the Sound Generator Board is attached, which allows you to access a small portion of the Rhythm Switch Board below. That is where you will find "terminal 5" (which is referenced in the service manual). Term5 is outputting a trigger at the tempo set by the front knob. Put the box in play, no rhythm buttons engaged, and run a wire from term5 to the sound you want to trigger. This generates a waveform at the 1/4" outs, at the same volume and sustain as the box normally outputs. 

Note: best not to use your own external trigger as this can produce lower gain sounds with erratic sustain, I experimented with this using my modular trigger outs, but ended up using the built in one.

Situated around the edge of the Sound Generation Board are nine terminals, which trigger ten sounds. Moving clockwise starting with the snare drum you will see terminals labeled: SD, HH, CY, C, RS, HB, LB, HC, BD. The RS terminal normally outputs a cow bell, but if you push the "bossa nova" button in around 3/4 (without actually making it click in) this terminal will output a rim shot (the service manual mentions something about grounding/ungrounding the CB SHUNT terminal to get these two sounds). 


On the sound generator board you will find eight off-white trimmers for tuning the sounds. These are labeled: BD DTHC DT, HC FRQLB DT, LB FRQHB DT, HB FRQ, and CY.HH.SD VAR.

TR-66 tuning trimmers

"FRQ" trimmers: these give you some control over the pitch of the three toms (HC, LB, HB), however the available range is narrow. If you go too low the drum may start to become a lump of noise with no  definitive pitch, and if you go too high it may start feeding back. Interestingly the snare sound contains the low bongo sound within it (the SD fundamental is fixed at around 280hz, and the LB is adjustable around 400hz). So tuning this bongo also changes the sound of the snare (I tune it to a just intonation relationship).

"DT" trimmers: these give you control of the decay time of the bass drum and the three toms. It is especially useful for the bass drum; you can get anything from a tight 65ms snap, and a long 650ms boom. 

"CY.HH.SD VAR" trimmer: this controls the level of the white noise. Turning this adjusts the snappiness of the snare, from completely muted (this could be considered a secret 11th sound!), to bright and raspy. Also, when sampling the HH/CY turning up this trimmer gives you a better signal to noise ratio. 


This old box uses a two prong ungrounded power plug and can be noisy.


Did a massive modular station remodel in 2017; busbar power distribution, metal rails, MOTM expansion to fill the case, custom mods, new keyboard and sequencer, and a mounting apparatus for the whole monstrosity...


Hinton busbar system

Installed a new power distribution system built by Hinton Instruments. Busbar is the ideal way to distribute power across large modular systems. This one was built to power a 35-unit MOTM system. 

The power supply rack mounts on the rear of the case. The busbars screw onto the rear wall vertically (this system has four bars +15V, -15V, 0V, and a +5V bar for the special MOTM-650 and 730 units). Power moves from the wall, to the power supply, to the busbars, and then to each individual module.

The new power system solved a problem I was having with envelope voltage bleeding into oscillator pitch, and some other weird stuff. Now everything is isolated and working perfectly. A stable modular system starts with well-designed power distribution, I should have done this from the beginning.

Also, Graham Hinton is a modular power supply wizard. He figures out what you need, measures every cable to be just as long as it needs to be to reach it's module, and attaches all the cables to the it arrives ready to instal! 


I took out my cabinet's wood rails and installed heavy-duty standard 19" studio rack rails. Penn Elcom makes some nice ones; you can order any odd length you need, and they are marked in one-unit increments. For this project I needed six 17U rails.

For installation I used L-brackets (30H x 80L x 20W mm). The rails already have mounting holes, so you just need to drill holes at matching locations on the brackets (mine already had holes in approximately the right places, I ended up with an oval hole after drilling it out some more). Then just secure the bracket to the rail using rack screws/nuts. In order to put two rails right up against each other with no gap, I had to space the bracket-holes differently for top/bottom rails, so the heads of the fastening screws didn't touch each other. If you do this project perform a lot measurements beforehand to make sure the modules you are going to install on the ends of each row aren't going to have any pieces behind their panel that touch your L-bracket or fastening screws. Also make sure you don't have any clearance issues where the metal beyond the rail's holes touches your module's pots.

1) Rack Screw, 2) Penn Elcom with washer, 3) Penn Elcom without washer, 4) MOTM screw.

MOTM was designed with professional studio standards in mind. That's great, but along with studio rack rails come chunky 10-32 rack screws to mount your modules (instead of the smaller screws people use with the lighter MOTM 19a rails). The solution I found is to use Penn Elcom M6 High-Point Rack Screws. These are the same diameter as standard rack screws in total, but have a detachable washer that makes up much of the diameter...toss that and find lower profile washer (I think 9.5mm outer and 4.3mm hole would work, but I haven't got mine yet, will confirm later).

Also, the Lamond Design cherry case needed a polish. Secret formula? Just shake 2/3 parts olive oil + 1/3 part white wine vinegar, rub in, wipe off. Easy and cheap. For scratches I used a 10% iodine solution; paint it on with a small modeling brush, and wipe off after around 10 seconds...keep doing that until the scratch is the same color as the wood.

Installed busbar power distribution system, and metal mounting rails for modules


What's MOTM? An engineering genius by the name of Paul Schreiber designed the MOTM Analog Modular Synthesizer system in 1998 (early on in the second-coming of modular). It's utilitarian, not fancy-looking, reasonably priced...and maybe the best synth in the world. Built for pro-studio use, reliable, constructed like a tank, and just all-around fantastic sounding.

MOTM expansion!

I already had 10 modules, and added another 25 to completely fill the cabinet. Previously I had mixed and matched modular systems in the same cabinet (just asking for problems), but with this remodel I decided to stop the madness and just make it a dedicated MOTM system. All built, and modified, by Frogleg Synthesis.

The system uses two MOTM-650 MIDI-CV converters; one receives data from the keyboard to output a melody, and the other receives data from the sequencer to output 4 other instruments. There is also a MOTM-730 pulse divider slaved to the sequencer's MOTM-650 click output. These three units aligned on the left side of the case are the controlling modules. From there signals flow rightward to oscillators, filters, envelopes, and out 6 voltage-controlled amplifiers on the right side of the cabinet, to the speakers and tape.


All the MOTM-300 and MOTM-310 oscillators got a Fine Tune Mod. For whatever reason the "fine" tune on MOTM systems covers a full octave. I had my units modified so the knob covers around 50 cents. That let's you easily fine tune to the pitch, and then dial in common +/-1-10 cent detunings. And with me, I tune to 1/10 cent using a digital strobe, so this smaller knob-range makes that easy (previously, even breathing on the knob moved it like 5 cents!).

The MOTM-800 Envelopes got a LED Mod which adds a Tellun LED circuit. This gives you 4-stage ADSR visual feedback (a bright flash for the attack/decay, decreases to sustain level, and then fades out with the release). Very informative, plus it adds some much needed "bling" to the utilitarian MOTM style. Also, mine were built to give off some serious flash, not a tame LED.

The MOTM-800s also got an Attack & Decay Mod. When I measured the attack times, I found that knob settings 0-3 covers 0.5-100 milliseconds, and the longest setting of 10 is around 4 seconds. But for normal use (not slow ambient music) common attack times would be 1, 3, 10, and 30ms. I found it was not only hard, but impossible, to dial in some of these settings. The reason is that there are jumps when turning the knob; at 0 the attack is a clicky 0.5ms and it stays that way until 2 where it jumps to 10ms, and then by 3 it is 100ms. The mod Pete at Frogleg Synthesis is working on would give more resolution and smoothness in the 0-5 knob positions for dialing in common 1-50ms attack times (and the same thing for the decay times). And then I'm leaving half of my 800s unmodified for slow stuff. I'll post back once we get it figured out. 

All modifications by Frogleg Synthesis.


The keyboard was updated to a Native Instruments Komplete Kontrol S49, which I can verify communicates excellently with the MOTM-650 MIDI-CV converter. The keyboard sends note, gate, pitch wheel, and mod wheel information to the modular (you can also map the knobs on the keyboard to AUX 1-4 of the MOTM-650, although I don't see any point in doing this since you can just tweak the knob on the synth). It has an advanced cord and arpeggio section which will be useful. It uses touch wheels, I'd prefer good old-fashioned mechanical wheels, but these work great and I think I'll be able to adapt my playing. My only complaint; why are these midi keyboards so friggin' large!? There is a lot of bulk that could be cut out of this unit.

For modulation control, in addition to the mod wheel on the keyboard, I'm also using a Moog EP-3 Expression Pedal into a MOTM-850 Pedal Interface. The mod wheel CV and pedal CV both go into a MOTM-190 dual VCA, which can then be routed out to whatever modulation destination. 

Maschine Studio + Komplete Kontrol S49

I finally sold my MPC-3000 and am using a Native Instruments Maschine Studio as the sequencer now. I have a library of sounds from rhythm machines I've sampled over the years, and this unit can trigger those individual samples, or play back entire rhythm loops with the ability to adjust the tempo (it splices the loop into hits and then adjusts their spacing). It's also good for creating arpeggiation sequences. Maschine has three MIDI outputs: output 1 goes to the modular synth, and outputs 2-3 send MIDI cc data to the Moogerfooger effects rack. This lets you control the parameters of the MF-104 Delay and MF-108 Cluster Flux Chorus (especially tempo tempo sync). So the sequencer is outputting 1) rhythm machine samples, 2) MIDI to the modular synth to be converted into CV, and 3) two channels of MIDI cc to the effects rack. 

All the instruments and effects that get recorded are still analog, but there is now a digital front-end triggering them.


When doing multitrack recording Maschine syncs nicely to Nuendo (DAW). You just create a channel in the DAW, and insert Maschine as an instrument. At that point Maschine is slaved solidly to Nuendo's master clock. Anywhere you jump to in your DAW project, Maschine goes to that spot in its sequence.

Basically I just use Maschine as a "plug-in beat maschine", referencing rhythm samples on my hard-drive...and overdub modular synth on top. And as the project progresses you can do a digital bounce to print the rhythm to 16 audio tracks.

Also, Machine helps for doing tempo-synced overdubs. If you plug in the Maschine hardware controller, then you can send midi from Maschine running in Nuendo, to the Maschine controller, and out its MIDI port to the modular synth (MOTM-650)—good for overdubbing tempo-synced stuff like arpeggios or echoes. Sync can be a nightmare so it's great to have a solid chain of command: Nuendo is the clock boss, sending orders to the Maschine hardware controller, which in turn sends orders to the modular synth and moog effects. 


The master plan!

Bringing it all together—I made a thick wood platform that gets "sandwiched" between the modular cabinet and a Z-stand. Four screws secure the platform to the base of the cabinet so it doesn't slide around.

The keyboard floats on this platform, and with the heavy modular and thick platform, it's all very stable. Screwed onto each side of the platform are metal hooks to conveniently hold patch cables.

An industrial power strip is screwed to the underside of the platform, with holes drilled so the keyboard/sequencer power cables pass thru to the strip below. When you sit down at the modular you just hit the button under the keyboard and the whole station powers on—modular, keyboard, sequencer and monitors! 


Platform with keyboard

Patch cable hooks, left

Patch cable hooks, right

REPATCH! by BendingBus

Live Patch #004. A sizzling "repatch" of last month's patch. Uses a MacBeth MK-1 Oscillator 'B' into a Moog Clusterflux stereo chorus for the main arpeggio at 0:07, then another MacBeth osc for the glide-lead at 0:23 (with some stereo spring reverb and a Moog delay). Messed around with the MOTM-730 to trigger the "lead", and at 1:54 switched the whole piece to double time. Also some bandpass filter tweaking of white noise throughout, using a MacBeth Filter 'B'. Drums are CR-78 sounds.

Enjoy, full-res audio downloadable here.

MODULAR POP W/ CR-78 by BendingBus

Live Patch #003. Had this idea patched up for around a month, and worked on it on and off, before finally hitting record. Yes, you can synth-pop on a modular! Now to the technical talk...

The basics of the patch use a MOTM-730 Pulse Divider to ping the modules rhythmically (the left/right tones, and the center melody which plays triplets). These pings are slaved to the rhythm sequencer's clock, which is loaded up with some CR-78 samples (sampled by super-producer Dom Morley). I ended up using a digital sine (programmed in the sequencer) for the bass, normally I don't use digi, but it's good for a clean (no harmonics) sine.

The in-your-face filtering @ 0:10 is a MOTM-410 into a Moog Cluster Flux chorus for some stereo width, then into an API 550EQ + 2500 compressor for midrange glory. The melody @ 0:36 is a MacBeth MK-1 voice, featuring some stereo spring reverb compressed thru an LA2A for a nice ambiance. Around half way thru @ 2:23 I turn on a sizzly MacBeth pulse wave riff which is playing an arpeggio from the MOTM-650, compressed thru an 1176 for bite. Near the end @ 4:30 you can hear the background texture more clearly which is an arpeggio thru a Moog stereo 12-stage phaser in a bath of Harmonizer echoes.

You can also download the full resolution studio master.

NEW STUDIO by BendingBus

The modular station is all set up in my new studio in Seoul, ready to record! Going to film a new set of live patches, and then try to get an EP released late this year.

Also doing a modular expansion. Switching to a busbar power system for cleaner power and better tuning stability, adding 25 new MOTM modules to the main cabinet, and building a "header" cabinet to house the row of MacBeth MK-1 modules. It's growing!

Modular Station, 2017

REVIEW OF 7-INCH by BendingBus

WCBN 88.3FM in Michigan...

“Pleasant downtempo instrumental pop made with old-school analog synths. Surprisingly, this doesn’t try too hard to sound retro. It’s not some sort of intentionally kitschy thing like Moog Cookbook (probably a really outdated reference but whatever, I still love their albums). It’s gently playful, but not novelty music. It’s more like an electronic lullaby than anything else, like Solvent putting his kids to bed (or somebody’s kids, I don’t know if he has kids). 

Or think Raymond Scott’s Soothing Sounds For Babies, but actually soothing rather than manic, and short and structured to fit on a 45. Or maybe this is an artifact from an alternate universe where Plone became the biggest band in the world, and this is a tour-only 7″ from their 5th world tour following their 8th consecutive #1 album. 

The dream only gets wider and deeper. The B-side is an even more mellow version of the A-side, for sweeter dreams.” 

- The Answer Is In The Beat (December 5, 2016)

  And With Each Step a Wider and Deeper Dream  (7" vinyl)

And With Each Step a Wider and Deeper Dream (7" vinyl)

7" VINYL SINGLE by BendingBus

And with Each Step a Wider and Deeper Dream, a two song single available on 7-inch vinyl, CD singles, and digital download. The 7-inch was well received by college radio electronic music specialty shows, charting at KALX Berkeley, KDVS Sacramento, and other fine independent stations. Check it out here

  And With Each Step a Wider and Deeper Dream , 2016 (VL, CD, DL)

And With Each Step a Wider and Deeper Dream, 2016 (VL, CD, DL)


Here is the process for customizing the MOTM-650's tuning table with your own tunings (using a mac). If you found this page that was the hard part, the process is actually quite easy. The MOTM-650 uses Midi Tuning Standard (MTS), which was designed by Robert Rich back in the early 90s. You just need a simple program to write MTS files, and transfer them into the 650.

The Process on Mac:

  1. Download Max Magic Microtuner (MMMT), and get a license.

  2. Connect a Midi In/Out interface to your mac (something simple like the M-Audio Uno will work), and connect the in/out cables to the MOTM-650.

  3. Open MMMT, and select your Midi interface on the Midi Settings Palette, from the drop down list.

  4. Now create a custom tuning using the MMMT program (you might need to read the instructions).

  5. Alternately, if you are like me and find MMMT excessive, you can import a standard Scala (.scl) tuning file into MMMT. Just click the "Import SCL" button. Make sure the "Expand at Load" box is checked so that your scale expands to cover all octaves. If you don't know, a scala file is a very simple text file, it's just a list of pitch ratios, or cents.

  6. Finally, send the tuning from MMMT to the MOTM-650. From the Midi Settings Palette click "Send tuning via SysEx". A box will come up with a few options. Leave everything alone except 1) select the tuning program number you want to overwrite [you can't overwrite #0 equal temperament, so start your tunings at #1], and 2) type in an eight character name. Click send.

Your new tuning should now be in the MOTM-650!