MCHammon: a free Hammond B3 on a Linux laptop, and the road to two manuals and a real Leslie.

You can play a convincing Hammond B3 with a MIDI keyboard you already own, a USB-MIDI interface and free software. Ours is a 61-key Yamaha PSR-275 connected through a Roland UM-ONE to a laptop running Linux Mint and setBfree, a free, open-source model of the B3’s tonewheels and its Leslie speaker, with a drawbar-and-tabs front end John wrote for it. The sound comes out of the laptop’s own speakers or headphones, the Leslie is simulated, and the keyboard’s sustain pedal flips it between slow and fast like a B3’s half-moon switch. That’s MCHammon today: one manual, and nothing spent on software. The plan is two manuals and a real Leslie, fed a dry signal from an audio interface with the simulation switched off. A real Leslie needs care first: a vintage one’s 6-pin plug carries mains voltage, and a US-built cabinet must never go straight into an Australian 240 V outlet.

Where it stands (13/10/2026). Built and playing: one keyboard on Linux, with a simulated Leslie. Not built yet: a second manual (the Casio CT-S100 we meant to use lost its USB socket on 13/10/2026), a swell pedal, an audio interface and a real Leslie. Everything under Where it’s going is the plan, not something we’ve done.

If you’re adding a real Leslie: check it first. Read the voltage on its rating plate. If it says 117 V or 120 V, or it’s a vintage cabinet you don’t know the history of, don’t plug it in. Have it checked by someone who services Leslies first. The safety section explains why.

What’s running now: a free one-keyboard B3 on Linux

The whole rig is one keyboard, one small interface and one laptop. Nothing in the chain needed a driver from its maker.

The keyboard: a Yamaha PSR-275

The PSR-275 is a home keyboard, not a controller, but it does the job. Here’s what its manual says, next to the Casio we planned as the second manual:

Sources: Yamaha PSR-275/PSR-273 Owner’s Manual; Casio CT-S100 User’s Guide and CT-S100 MIDI Implementation. Checked 13/10/2026.

What that meant in practice:

• It needs a USB-MIDI interface. No USB port means the Yamaha’s MIDI OUT has to go through an interface to reach the laptop. Yamaha’s own manual shows the same hookup with its long-discontinued UX16.
• Its channel is fixed, and that’s fine. The manual never says which channel the keys send on. Our front end treats MIDI channel 1 as the upper manual, which is how setBfree is set up out of the box too, and that’s where the Yamaha plays.
• It sends notes an octave low. Our PSR-275 sends notes 24 to 84, an octave below the 36 to 96 you’d expect from a 61-key keyboard, so the bottom octave was silent at first. The front end now transposes everything up 12 semitones by default.
• It chatters. The Yamaha sends a constant stream of MIDI clock. It looks like activity on the cable, but it isn’t notes, so don’t take it as proof that the keys are getting through.
• Its own buttons can’t upset the organ. The front end uses its own private controller numbers and switches off setBfree’s default controller map and preset program changes, so pressing voice buttons on the Yamaha changes nothing in the organ.
• Touch response doesn’t matter, and nor do synth-action keys. A tonewheel organ plays at the same volume however hard you hit the key, and although real B3s have “waterfall” keys with square fronts, ordinary keys play organ perfectly well.

Turn the Yamaha’s own volume down while you play (or switch Local Control off), so you hear only the organ.

The interface: a Roland UM-ONE

The UM-ONE is a USB cable that ends in one MIDI IN plug and one MIDI OUT plug. On Linux it’s class-compliant: the standard Linux USB audio driver runs it and there’s nothing to install. Once it’s plugged in, aconnect -l lists it as “UM-ONE”.

• Wire it the right way round. The plugs are labelled from the interface’s side, so the plug marked IN goes into the keyboard’s MIDI OUT. That’s how Roland describes the mk2, and ours is wired the same way. It looks backwards the first time.
• Set the switch to COMPUTER. Ours has a switch marked COMPUTER and MIDI, and it must be on COMPUTER. That switch suggests ours is the original UM-ONE. The newer UM-ONE mk2 has a COMP/TAB switch instead: TAB is class-compliant mode, using the driver built into the computer, and COMP uses Roland’s own driver (Roland support). On Linux, a mk2 belongs on TAB.
• If nothing plays, check those two things first: the switch, then the plugs. Our build notes list exactly those two causes when nothing arrives.
• On Windows, look for the same thing: “class compliant” or “no driver needed”. Windows has two built-in drivers for class-compliant USB MIDI devices, and a device that needs a driver from its maker can’t use either.

The engine: setBfree on PipeWire

setBfree is a free, open-source (GPL-2.0) emulation of a tonewheel organ and a Leslie: drawbars, percussion, vibrato and chorus, key click, leakage between tonewheels, overdrive, reverb and the rotary speaker. Like a real B3 it has an upper manual, a lower manual and pedals, listening on MIDI channels 1, 2 and 3 by default (x42). We run version 0.8.12, the one in Linux Mint’s packages; the current release on x42’s site is 0.8.17.

On Linux it runs as a standalone JACK program. Linux Mint 22.3 uses PipeWire for sound, and PipeWire runs JACK programs through its pw-jack wrapper, so there’s no separate JACK server to set up.

Latency. PipeWire on our laptop runs at 48 kHz, and its default buffer (the “quantum”) is 1024 samples, about 21 ms. That’s sluggish for an organ, so our front end starts setBfree with PIPEWIRE_LATENCY=256/48000, asking for 256 samples, about 5.3 ms per buffer. PipeWire treats that as a request, not a guarantee, though the latency it settles on won’t be larger. A common rule of thumb for organ is to keep key-to-sound delay under about 10 ms. We haven’t measured ours end to end yet, and we’ll add the figure here when we have.

The Leslie simulation. setBfree’s Leslie is switched on in our rig. Its settings: horn 40 rpm slow and 423 rpm fast, drum 36 rpm slow and 357 rpm fast, with the two horn microphones 180° apart. It starts at slow.

The front end: our “Hammond B3” app

setBfree can run with no window at all, controlled entirely by MIDI. John wanted something that looks and plays like the real console, so he wrote a front end for it in Python and PyQt6. Its look is styled after Sampleson’s CollaB3 V2 organ plugin; it has no connection with Hammond or Sampleson. It starts setBfree and runs it, sends it MIDI controller messages, and connects the keyboard.

• Two views. A console view drawn like a real B3, and a rotary view with the Leslie controls.
• The console. Nine drawbars for the upper manual. B3-style tilting tabs for percussion on/off, soft/normal, fast/slow and 2nd/3rd harmonic, vibrato and chorus on, and the V1–V3 / C1–C3 selector. Two 61-key manuals drawn on screen, with B3-style reverse-coloured preset keys. The keys light up as you play, and you can click them to play.
• Knobs. Volume, Reverb, Drive (overdrive), Leak (tonewheel leakage) and Click (key click).
• Leslie controls. On/off, slow/stop/fast, horn and drum speeds, acceleration, horn level, horn leak, the microphone setup (two horn mics at an angle, or a single mic) and mic distance.
• Presets. 25 factory drawbar registrations taken from setBfree’s own program list, including “Jazz (Jimmy Smith)”, “Booker T Jones”, “Green Onions 2”, “Procol Harum”, “Steve Winwood 1”, “Joey DeFrancesco 1/2”, “Brian Auger 3rd”, “Gospel” and “Blues 1/2”. You can save your own too.
• The sustain pedal is the half-moon. Press the Yamaha’s sustain pedal and the Leslie flips between slow and fast, the job a B3’s half-moon switch does.
• A settings menu with the MIDI keyboard choice, Transpose, “Restart sound engine” and “Reset all controls”, and a status line that shows which keyboard is connected.
• A headless launcher that runs the organ with no window, for testing.

How close is it to a real B3?

The front end comes with an accuracy test suite that checks setBfree’s output against how a real B3 behaves. Our build notes record these results:

Those are measurements, not a listening test. As for how it plays: on 12/10/2026 John asked for it to be connected so he could play, and he was playing it that evening.

Problems we hit, and the fixes

None of these was hard once we’d found it. All of them cost time until we had.

We haven’t had stuck notes, crackles or dropouts so far.

What one keyboard can’t do yet

MCHammon plays only the upper manual for now. Nothing drives the lower manual or the pedals, and there’s no keyboard split: the on-screen lower keys sound the upper registration when you click them. The front end is set up to show notes arriving on MIDI channel 2 on its lower manual, and channel 2 is setBfree’s lower manual by default, so that’s where a second keyboard will go.

Where it’s going: two manuals and a real Leslie

Everything from here on is the plan, written up from John’s setup plan and checked against makers’ manuals and pages on 12 and 13 October 2026. None of it is built yet. The plan was first written for Windows, with GSi’s VB3-II organ and a Focusrite Scarlett 2i2 audio interface. Now that setBfree is playing on Linux, which engine and which computer the finished rig uses is an open question; the rest of the plan applies either way.

Why a real Leslie, and why the simulation goes off

A Leslie is an amplifier with two rotors: a horn spinning on top for the treble and a drum spinning underneath for the bass. The movement does three things at once. The pitch wobbles as each rotor swings towards you and away (the Doppler effect), the volume swells and fades, and the sound bounces around the room from a moving source. When you flick from slow to fast, the light horn gets up to speed in a second or so and the heavy drum takes noticeably longer. That lag is the sound.

setBfree models all of this, and through headphones it’s very convincing. But a simulated Leslie still comes out of speakers that don’t move; a real one moves the air in the room. So the plan is to let the computer do the tonewheels, drawbars and percussion, and hand a dry organ signal to the cabinet. If the simulation stays on, you get a simulated Leslie played through a real one: two rotary effects on top of each other, and it sounds like a washing machine. Speed moves to the cabinet too: a real Leslie is switched with its own footswitch or half-moon, and our sustain-pedal trick only drives the simulation. We’ll add how the real cabinet compares with setBfree’s simulation once one is connected.

The organ engine: stay on setBfree, or move to VB3-II?

Staying on setBfree means turning its Leslie off with whirl.bypass=1 (GitHub), its reverb to zero with reverb.mix, and its overdrive off, so the cabinet gets a dry organ. Our front end already has a Leslie on/off control. On Windows, setBfree’s 64-bit build runs as an LV2 plugin inside a host such as REAPER, which has supported LV2 since version 6.24 and has a fully working 60-day trial.

Moving to VB3-II buys a polished, documented two-manual organ. Its free demo goes silent for 2 seconds every 30 and can’t load or save files, which is still enough to prove a rig before paying. For a real Leslie, GSi’s manual says to switch Rotary OFF; set Overdrive and Reverb to 0 as well, because both can still reach the Leslie with the rotary bypassed. Each manual can listen on any MIDI channel, and with one keyboard its SPLIT button divides it between the two manuals, at middle C by default.

The second manual

The plan’s second manual is the Casio CT-S100, and its only MIDI connection is the Micro-B USB socket that broke. Without it the Casio still plays through its own speakers, but it can’t send MIDI (User’s Guide). There are three ways back to two manuals, and we haven’t picked one yet:

• Casio’s Australian distributor. Shriro Australia’s Casio site has a “Request a Repair” form, but its five-year conditional warranty excludes accidental damage, so expect to pay.
• An electronics repairer. An iFixit answer about this exact keyboard says the socket is usually held by four solder points and can be replaced with hot air and flux once the board is out: fine board-level work for a repairer. Shriro’s warranty excludes problems caused by repairs outside a Casio authorised service centre.
• A different second keyboard. Any class-compliant USB-MIDI keyboard will do, and touch response doesn’t matter for organ. Best is one that lets you set its sending channel, so it can go on channel 2. One with a fixed channel works too, as long as it isn’t the Yamaha’s channel 1.

Once a second keyboard works, set it to channel 2, which setBfree and VB3-II both treat as the lower manual. On the Casio, switch off its Sustain function as well: its MIDI implementation shows it sends a release-time message, not a sustain pedal. On both keyboards, turn off anything that adds or moves notes: split, layered voices, accompaniment and octave shift.

Protect the port. USB-IF’s Micro-USB specification designs the connector for 10,000 insertion cycles, but sideways force is another matter: its wrenching test, marked “reference only”, expects no damage only up to 25 N (roughly the weight of 2.5 kg) on a plug. Use a short or right-angle cable, tie it to the stand so a tug pulls on the tie and not the socket, and don’t leave it hanging where a foot can find it.

The swell pedal

On a real B3 the swell pedal is how you play dynamics, so it’s next on the list after the second keyboard. Today our volume is the on-screen knob, which drives setBfree’s swell. Neither keyboard has an expression-pedal jack, so the plan is a USB adapter such as the Audiofront MIDI Expression (US$49 at its 2013 launch; we couldn’t confirm a current price), with an expression pedal on common wiring such as a Roland EV-5 or an M-Audio EX-P on its “M-Audio” setting. Avoid high-resistance pedals: Arturia advises against pedals over 25 kΩ, because they reach full value over only a small part of their travel. The pedal’s controller then has to be mapped to the swell. VB3-II listens for controller 11 (expression).

Physical drawbars can wait. Ours are on screen, and Crumar’s DK61 (A$1,199 at AWAVE), a waterfall-key keyboard with nine real drawbars, is the upgrade if we ever want them under our fingers.

Safety first: vintage Leslies

This is the section to read twice. A Leslie isn’t a guitar amp with a spinning bit on top. Old ones carry mains voltage in places you wouldn’t expect, and many in Australia were built for American power.

Voltage. Hammond’s manual says to operate a Leslie only at the voltage and frequency on its nameplate. US units are built for American power (around 117–120 V) and must not be plugged straight into Australian 240 V. Converted 230 V versions of the 122 and 147 are normal: a 230 V replacement transformer has a 117 V tap so the motors still get the voltage they need. Read the plate before anything else.

The vintage 6-pin plug is live. On a vintage 122, two pins of the 6-pin connector carry mains voltage, another carries the amplifier’s B+ high-voltage DC supply, and the speed is switched by more than 35 V DC sent down the audio pair. Never improvise an adapter, and never wire a 1/4″ jack onto a 6-pin cable. A purpose-built interface box exists precisely because this connector isn’t an audio input.

Old cabinets need a check-up. Fifty-year-old capacitors, power cords and relays wear out. Have a vintage cabinet looked at by someone who services Leslies before you use it regularly, and before you power it at all if it’s a 117 V unit or you don’t know its history. Work on mains wiring is a job for a qualified technician. This is general information, not electrical advice.

Places that offer Hammond and Leslie service (from their own websites, checked 13/10/2026; we have no connection with any of them):

• Standard Ampworks, Ryde NSW: authorised warranty service for Hammond and Leslie, with on-site service calls across the Sydney metropolitan area.
• Doppler Audio, Mirboo North VIC: servicing and restoring tonewheel Hammond organs and Leslie cabinets, including Leslie connection and switching.
• Hammond’s Australian importer: Musico, Ringwood VIC, which brings Hammond organs and Leslie speakers into Australia and lists an on-staff technician and service department. (The same Ringwood business trades as Hammond Australia / Bernies Music Land, according to its 2019 trade-show profile.)

We haven’t connected a Leslie yet. When we do, we’ll add its model, socket and rating-plate voltage here, and who checked it before it was first powered.

Connecting the Leslie

What sits between the audio interface and the Leslie depends entirely on the model and its socket. A modern Leslie with a 1/4″ input takes a plain cable; a vintage 6-pin 122 or 147 needs a purpose-built preamp and interface.

Prices are as each seller showed them on 13/10/2026, in the seller’s own currency.

• The 122 and 147 pinouts are different. Hammond says a kit for a 122 will not work with a 147.
• A 240 V 147 may have a 120 V or a 240 V speed relay (Trek II). Check the sticker on the amp or the relay before you order an interface.
• Vintage 122s have no stop, only slow and fast. A relay kit (Trek II’s EIS-122, US$101; the 122A needs the EIS-122A) adds brake-to-stop, switched from a three-position control.

Level. A modern Leslie’s line input is very sensitive: the sister model 3300 is rated at 100 mV (−18 dBu), while a Scarlett 2i2 4th Gen can put out +16 dBu. Start with the interface’s output knob low and bring it up slowly; the 3300 manual warns that excessive input can seriously damage the Leslie. Hammond’s 122/147 manual sets gain by raising the Leslie’s volume until the sound begins to distort, then backing off, and warns that playing it distorted for long periods can cause severe damage.

Hum. A computer and a valve amp on different power points can hum. Plug the computer, the interface and the Leslie into the same power board. If it still hums with nothing playing, put a transformer-isolated DI box or line isolator between the interface’s output and the Leslie.

Latency on Windows. If the finished rig moves to Windows, the plan follows Focusrite’s own guides for the Scarlett: its ASIO driver (installed with Focusrite Control 2), 48 kHz and a 256-sample buffer to start, raised as far as 1024 if the audio glitches, Focusrite’s Windows optimisation steps, and at least 15 minutes of LatencyMon while playing. One catch: the 2i2 4th Gen’s headphone output carries the same feed as outputs 1 and 2, so with the rotary off your headphones hear the dry organ too. Keep a rotary-on setting for headphone practice.

Building the console

Most two-tier keyboard stands put the tiers far too far apart for organ, where you slide between manuals mid-phrase. These are the targets. They’re approximate, so measure a real B3 at a dealer before cutting any timber.

For scale, Hammond’s service manual gives the B-3’s case, closed and without pedals, as 48⅜″ wide, 28¾″ deep and 38⅜″ high (about 1229 × 730 × 975 mm).

Stand or frame? The Ultimate Apex AX-48 Pro (A$399 at Mega Music; A$499 for the Pro Plus bundle) is the cheapest adjustable stand we found, but Ultimate doesn’t publish its tier spacing. The K&M 18860 Spider Pro (A$1,000 at Turramurra Music, sold out when we checked) has support depth adjustable from 300 to 470 mm and takes 35 kg per tier. The cheapest way to get the step and setback exactly right is a DIY frame built to the numbers above. We haven’t built ours yet; with one keyboard, there’s nothing to stack.

Registrations to start from

Drawbar settings are written as nine digits, one per drawbar from 16′ to 1′, each 0 (in) to 8 (fully out): 16′ 5⅓′ / 8′ 4′ 2⅔′ 2′ / 1⅗′ 1⅓′ 1′. Set vibrato/chorus to C3. These are common starting points, not rules; move them while you play. Our front end’s 25 factory presets are another good place to start.

With one keyboard, only the Upper column applies for now. VB3-II follows the real B3’s rules: percussion only works on the upper manual’s B drawbar set, and switching percussion on silences the upper 1′ drawbar.

Gain staging into the Leslie (planned). Rotary simulation off, overdrive and reverb at zero, the organ’s volume at about 75%, the interface’s output low. Raise the Leslie’s volume until it starts to break up on full chords with the swell pedal down, then back off slightly. Add the organ’s overdrive only if you want more growl than the Leslie’s amp gives on its own. If the cabinet sounds harsh, lower the key click before touching anything else.

Speed. Slow (chorale) for comping, fast (tremolo) for builds, switched at the Leslie. Listen for the horn and the drum ramping at different rates. That’s the sound you buy a real Leslie for.

Build order from here

Get each stage playing through headphones before adding the next, and add the Leslie last, so if something goes wrong you know which stage it’s in.

1. Done: one keyboard on Linux. The Yamaha through the UM-ONE into setBfree, with a simulated Leslie on the laptop’s speakers or headphones.
2. A second keyboard, repaired or replaced, on MIDI channel 2. Check that the top keyboard plays only the upper manual and the bottom only the lower, then set up bass at the bottom of the lower manual.
3. The swell pedal, through a USB adapter, mapped to the organ’s swell.
4. Check the Leslie before powering it. Note the model, the socket (1/4″, 11-pin, 8-pin or 6-pin) and the voltage on the rating plate. If it’s a 117 V unit or a vintage cabinet of unknown history, have it checked first. Order the interface or footswitch it needs.
5. Add the Leslie. Settle the engine and the audio interface, switch the rotary simulation off, turn everything down, connect output 1, then bring the levels up as above. Test slow, fast and stop (if fitted) on the Leslie’s own switch, and listen for hum with nothing playing.
6. Build the console to the measurements above. Bass pedals can come later: a MIDI pedalboard on channel 3, such as the Studiologic MP-117 (A$909 at Mannys), whose only port is a 5-pin MIDI Out, so it needs a USB-MIDI interface too. Until then, a split can put bass at the bottom of the lower manual.

When it goes wrong

Most problems with a rig like this are MIDI wiring and channels, buffer size or earth loops, in that order.

Common questions

Sources

We opened and checked every source below on 13/10/2026 unless another date is given. Prices are as each seller quoted them that day.

Our build notes

• MCHammon build notes, 13/10/2026: the rig’s configuration, the front end’s README and source, and its accuracy test results, checked read-only on the laptop that runs the rig.

Organ engines

• setBfree, x42 plugins (version 0.8.17, Windows installers, default channels 1/2/3). x42-plugins.com
• setBfree source and README (licence, whirl.bypass, reverb settings), GitHub. github.com · setBfree project site
• GSi VB3-II Tonewheel Organ Simulator, product page (version 2.3.1, price), Genuine Soundware. genuinesoundware.com
• VB3-II 2023 Edition User Manual (rotary on/off, overdrive, outputs, MIDI channels, demo limits, SPLIT), Genuine Soundware. genuinesoundware.com
• VB3-II User Manual, 2018 edition (two 61-note controllers, default MIDI CC map), Genuine Soundware, October 2018. PDF
• CollaB3 Free and CollaB3 Pro, Sampleson. Free · Pro
• Hammond B-3X, IK Multimedia (price). ikmultimedia.com
• B-3 V, Arturia (price). arturia.com

Keyboards, interfaces and controllers

• PSR-275/PSR-273 Owner’s Manual (specifications, MIDI functions, MIDI implementation chart dated 29/01/2003), Yamaha. PDF
• CT-S100 User’s Guide (CTS100-E-2B), Casio. PDF
• CT-S100 MIDI Implementation, Casio. PDF
• UM-ONE mk2 product page (MIDI IN/OUT plug labelling), Roland. roland.com
• UM-ONE mk2: Connecting to a Computer (COMP/TAB switch), Roland Support. support.roland.com
• DK61 product page and specifications, Crumar. crumar.it
• MP-117 specifications, Studiologic. studiologic-music.com
• Audiofront MIDI Expression launch report, rekkerd.org, 02/10/2013. rekkerd.org
• “Which expression pedal should I use with my Arturia keyboard?”, Arturia support. support.arturia.com
• Waterfall Key, Sweetwater InSync. sweetwater.com
• CASIO Music Instruments Warranty Conditions (5-year conditional warranty; accidental damage and non-authorised repairs excluded; Request a Repair), Shriro Australia. shopcasio.shriro.com.au
• “How Do I Repair the USB Port” (Casio CT-S100 Micro-USB port, answer of 10/02/2020), iFixit Answers. ifixit.com
• Micro-USB Cables and Connectors Specification, Revision 1.01, 04/04/2007 (10,000-cycle durability, wrenching strength), USB-IF; in the USB 2.0 specification package. usb.org

Linux, Windows and audio

• pipewire(1) manual page (PIPEWIRE_LATENCY), PipeWire. docs.pipewire.org
• How to switch between MIDI class drivers (the two built-in class drivers; devices needing a maker’s driver), Microsoft Windows MIDI Services docs. microsoft.github.io
• “Making music with MIDI just got a real boost in Windows 11”, Microsoft Windows Experience Blog, 17/02/2026. blogs.windows.com
• “Windows MIDI Services rollout: known issues and workarounds”, Microsoft Windows Music Dev blog. devblogs.microsoft.com
• Scarlett 2i2 4th Gen User Guide v4 (driver install, +16 dBu outputs, headphone feed), Focusrite. PDF
• Optimising Windows for audio, Focusrite support. support.focusrite.com
• Troubleshooting glitchy audio on Windows (buffer size, LatencyMon), Focusrite support. support.focusrite.com
• LatencyMon, Resplendence Software. resplendence.com
• REAPER purchase page (licence price, trial) and change log (LV2 support), Cockos. Purchase · What’s new
• Cantabile editions compared, Cantabile. cantabilesoftware.com
• Gig Performer store (prices). gigperformer.com

Leslie: manufacturer and parts

• Leslie specifications (981 and others), Hammond. hammondorganco.com
• Leslie 122/147/981/147A product page (122 and 147 pinouts differ), Hammond. hammondorganco.com
• Leslie 122A/122XB/147A Owner’s Manual (nameplate voltage, gain setting, Interface Panel, FS-10TL), Hammond. PDF
• Leslie 3300 Owner’s Manual (line input 100 mV / −18 dBu, FS-9H tap and hold), Hammond. PDF
• FS-9H footswitch, Kraft Music (price). kraftmusic.com
• Eleven, Crumar (features). crumar.it · price at Perfect Circuit
• Fusion Preamp Interface, BookerLAB (features, prices, backorder). bookerlab.com
• UC-1A, Trek II (outlets, price, stock): 220 V · 110 V · UC-1A and 240 V 147 relays
• EIS-122 relay kit, Trek II (price, brake-to-off). trekii.com
• Mains transformer for Leslie 122/147, 230 V with 117 V motor tap, Tube Amp Doctor. tubeampdoctor.com
• Leslie 122 interface build (6-pin pin functions, speed-switching voltage), PedalPCB forum, 19/08/2026; read via the Internet Archive’s copy of 10/10/2026. forum.pedalpcb.com

Service in Australia

• Standard Ampworks, Ryde NSW. standardampworks.com.au
• Doppler Audio, Mirboo North VIC. doppleraudio.com.au
• Musico, Ringwood VIC (Hammond and Leslie importer). musico.com.au
• Hammond Australia exhibitor profile, Australian Musician, 03/07/2019. australianmusician.com.au

Console layout and stands

• “Keyboard Height?” (1974 B3 measurements), Nord User Forum. Read by John on 11/10/2026; the page was blocked to our checker on 13/10/2026. norduserforum.com
• “Making a keyboard stack” (103 mm setback, 65 and 68 mm steps), Hauptwerk forum. forum.hauptwerk.com
• AGO specs for keyboards (29.5″ minimum to the lowest manual, 63 mm spacing), Hauptwerk forum. forum.hauptwerk.com
• Hammond Organ Service Manual (B-series case dimensions), 2016 edition, Internet Archive. archive.org
• 18860 Spider Pro keyboard stand, König & Meyer. k-m.de
• Apex AX-48 Pro Plus, Ultimate Support. ultimatesupport.com
• Retail prices: Mega Music, AX-48 Pro · Turramurra Music, K&M Spider Pro · Mannys, MP-117 · AWAVE, Crumar DK61