Microtonal Mathematics by Motorola

Isn’t this thing (pictured below) awesome looking? Part home organ, part accordion, part microtonal super-genius. In early 2018, we relocated our super-rare Motorola Scalatron from the keyboard exhibit hall into our workshop for a quick tweak in advance of our upcoming microtonal summit. 


Tim Warneck, our synth tech, tested the four internal power supplies to see if they were doing their jobs properly. Once confirmed, we connected the external speaker, fired her up and the fun began.

Enter George Secor, discoverer of the ‘miracle temperament’ and developer of the Scalatron.  George rolled into EMEAPP with a hoard of unique accordions and an eagerness to feast upon our Scalatron.  We came to discover that ours is unique version, in that it has a top-mounted jackfield in place of the standard synth-like face board. It is also one of the very few (3, actually) that has a multicolored accordion-like 240 button generalized keyboard instead of a home organ-style dual manual keyboard.

Over the next few days, George answered a myriad of questions as we delved deep into this unique machine. He explained to us how microtonal scales work and how mathematical ratios can apply.  He also treated the EMEAPP crew to a private concert on the ‘Moschino free-bass’ accordion, as well as on our vintage Rocky Mount Calliope and Hohner Electronium accordion monosynth. But, the highlight was seeing George perform a few numbers on our unique Scalatron, just as he did decades back when he first got involved in the instrument’s development.

We are so appreciative of people like George, the visionaries and innovators who make our musical worlds a more verdant and expressive place to create.

A few weeks after we wrapped up this summit, we happened upon an ultra-rare Motorola Scalatron Frequency Generator specifically designed to calibrate the keyboard on eBay. We figured that the Scalatron itself is so rare, we couldn’t pass up on this equally rare peripheral. Here is what the seller had to say:


“Here is a very interesting unit.  The Motorola Scalatron was an electronic keyboard instrument that could be calibrated to play microtonal music in live performance.  Apparently, only 20 of them were ever made. Some of them had a couple of normal looking keyboard manuals and some had “chiclet” keyboards with patterns of keys.  There was a separate company, Motorola Scalatron, Inc. That made them in the 1980s.

The keyboard could be calibrated to play virtually any scale system.  For instance, one sytem that was used had 31 tones to the octave. It came with what looked like a regular Motorola television monitor that was used to program the desired frequencies.  It displayed a split screen with what looked like Stroboconn type wheels which would be adjusted until they matched. One of the monitors was apparently on eBay sometime in the past according to some discussion forums I found and they mentioned that it must have had some kind of frequency generator to feed it.  I believe this unit is probably what would have done that.

This unit powers up and it does produce audible tones.  There is an on/off switch and indicator light on the lower left. There is a knob to select notes from the regular chromatic scale and another that changes the octave that is sounded.  The 3rd big knob on the left side says P/M Range below it and Pulse above. The pointer can be moved to 1, +2 or +4. There’s a small switch in the middle that can be thrown to either Variable or Chromatic.  There are 10 pushbuttons along the top and you can push any number of them at the same time and they will stay down until you push them again and they come back up. There’s a jack labeled Microphone in the lower left corner.

Probably the only one of these you will see this week!”

Couldn’t have said it better. Rare stuff indeed!!!

Written by Drew Raison, photography by EMEAPP

R2D2? Space Heater? Digital Reverb?

This odd space heater-sized box is actually a digital reverb and quite a rare one at that. EMT (Elektro-Mess-Technik) was a turntable manufacturer in Germany, but they also had a keen eye for the development of artificial reverberation. Their Model 140 plate reverb changed the trajectory of music mixing back in the late 1950s. The 140 has remained a standard for analog studio reverb to this day, we even have one going into our recording studio. Over time, technology advanced and brought the flexibility of digital to the table.

Originally released in 1976 (and again recently, as a digital plugin), the EMT 250 broke new ground with its stunning depth and flexibility. To this day, it is considered by many to be one of the world’s best sounding digital reverbs, we certainly agree.


A reverb like this is beneficial in the creating of space ‘around’ a sound, it can add textural early reflections that broaden the soundstage and depth of a mix. This EMT 250 will be a perfect compliment to our even older EMT 140 stereo plate reverb.


The 250 is surprisingly well though out of and offers features that were innovative, it could even be configured as a multi-effect unit. It even has two sets of inputs and four discreet outputs. In addition to straight-ahead reverb, it has chorus, phase and delay effects. These units have become quite rare, as EMT only made 250 before releasing the 251 in 1979

Our EMT 250 digital reverb came from Mountain Studios in Montreux, Switzerland. Over the years, our unit provided stunning and shimmering reverb on dozens of critically acclaimed albums from bands like Emerson, Lake and Palmer, Yes, The Rolling Stones, David Bowie, Iggy Pop, AC/DC and a heap of records by the band Queen, who owned the studio for much of its life.

Written by Drew Raison, photography by EMEAPP

A Crusty, Old, Awesome Tape Echo

OLYMPUS DIGITAL CAMERAA big part of the inventive sound of the band YES, was their use of echo and delay on vocals and guitar. As the guitarist for the band, Steve Howe brought fresh sounds and a unique playing style. Singer, John Anderson, did the same with his upper-range, etherial vocal style.

Why is this particular rusty tape echo unit of importance to EMEAPP? Because it helped make musical history, both on stage and in the studio. It is a vintage Maestro EM-1 Groupmaster analog tape delay that has been ridden hard by years of touring with YES.

Many people ask us how we authenticate historically significant artifacts. Sometimes it can be quite difficult, as we search through the interwebs machine looking for an ancient photo of a performer on stage or in the studio with the item in question.

Here’s a shot of the Echoplex in question, sitting right behind Steve on stage with Yes back in the early 1970s. Is this proof that ours is the band’s original unit? Probably not, but it certainly indicates that he was using a Groupmaster back in the day.

Howe Groupmaster

Here’s the kind of proof that we appreciate, a snap of Steve with his arm on the actual delay, along with a certificate of authenticity.  Now, go put on “Fragile” and crank it up like you should. 🙂


Written by Drew Raison, photos by EMEAPP and Tom Cox

A Partial History of the String Machine

OLYMPUS DIGITAL CAMERAWe’ve been having some fun with ‘string machines’ here at EMEAPP. We recently received a pair of vintage Eminent organs that sparked a conversation about the origin of keyboards that focus on string ensemble-type sounds.

Our Eminent 310U Unique and its big sister, the Eminent 310T Theater were the leaders of the pack. They include a ‘Strings Ensemble’ section that spawned the creation of the ubiquitous stand-alone string keyboard. In addition to a believable string ensemble sound, these Eminent organs have a brilliant bucket-brigade chorus effect that has become a sonic flavor that most will recognize. In fact, the Eminent 310 Unique contained the first polyphonic string synthesizer on the market.

In 1972, Eminent organs brought the Unique to the public. It sold well to the home market, but they also spurred interest in the music production and studio world.  This unique string sound was noticed by composer/producer Jean-Michel Jarre, who used his 310s all over two of his critical releases, Oxygène and Équinoxe.

OLYMPUS DIGITAL CAMERAUpon realizing the potential of a stand-alone string synth, Eminent repackaged the string portion of the 310U into a single four-octave unit. They released this unit under their “Solina” brand name, and called it the “String Ensemble“.

In 1974, American synth maker, ARP, licensed the Solina and rebranded it under their badge. We have a unit with ARP stickers right over the Solina logo!

OLYMPUS DIGITAL CAMERAThe Eminent string sound was innovative, as were the electronics behind it. Its sound has become embedded in our musical souls and has graced huge hits in the disco, rock, jazz and prog world.

Keep your eyes open for an upcoming article that covers the ‘string machine’ derivatives from brands like Freeman, Roland, Crumar, Elka and many, many more.

Written by Drew Raison, photography by EMEAPP

What do Steve Howe, Bo Diddley and Bernie Worrell have in common?

They all used a Roland Jazz Chorus JC120 2×12″ solid-state guitar amplifier. These musicians were quite different genre-wise, but they all loved the sound that the legendary JC 120. Loud and clean, and a chorus effect that is totally worth the price of admission.

The sound of early The Police is a great example of this amp’s sound. Andy Summers’ clean and shimmery tone is proof that this amp is a real player. King Crimson’s stellar album, Discipline, has the Jazz Chorus all over it. Its clarity and presence are pretty much unmatched.


The unit on left was an amp that guitarist Steve Howe used with his bands Yes and Asia. The center amp was owned and used by legendary blues artist, Bo Diddley. His tone typically had chorus and tremolo, both sound great on this amp.  Lastly, the purple Jazz Chorus with the grille cloth removed was owned and used by Bernie Worrell, keyboardist for Parliament-Funkadelic, Talking Heads and Bootsy Collins.


The venerable Roland Jazz Chorus, or JC 120, has become a prime example of a clean, powerful and luscious guitar amplifier. First released in 1975, the JC 120 quickly rose into favor because of its reliability and reasonable cost, but also due to the stunning chorus effect built within. This ‘Dimensional Space Chorus’ effect was output in true stereo, giving a wide and open sound field. Throwing that magical chorus switch makes the amp sound six feet wide, it is quite an open and 3D sound.


Interestingly, the heavy metal community embraced the Jazz Chorus to provide its clean yet powerful tones. Since the JC 120 is solid-state, it doesn’t overdrive the signal as a tube amplifier might. This makes it a great candidate for a crystalline, strong amplifier for on-stage use. James Hetfield from the band Metallica is a Jazz Chorus user, as well as many others in the metal community.

Roland still manufactures the Jazz Chorus series, which shows its viability, especially after four decades of manufacture. If you get a chance, fire up one of these bad boys and take it for a spin, you’ll be impressed!

Written by Drew Raison, photography by EMEAPP