Is This Frank Zappa’s Secret Sauce? Here’s A Look At His Beloved MU-TRON BI-PHASE.

We have a few Mutron Bi-Phase phase shifters at EMEAPP, we adore them and their unique sound. While the majority of gear we have is in prime condition, Frank Zappa’s Bi-Phase has been ridden hard and put away wet. Saying that it was well-loved might be an understatement, it is clear that the Maestro and his techs spent many years disassembling and modifying this beloved unit.

If every piece of gear has a story to tell, Zappa’s Mutron can probably write a book. This is why it makes us so happy to see it make an appearance in this month’s GUITAR WORLD magazine. Dweezil Zappa even got involved to give the reader some insider info on this very special piece that was a critical part of his father’s sound.

As you’ll read in the Guitar World article, Zappa’s Bi-Phase is also well represented in the new book, STOMPBOX: 100 Pedals From The World’s Greatest Guitarists, chock full of sexy photos by our good friend Eilon Paz. Eilon visited EMEAPP to shoot a few dozen rare and unique pedals for this book as well as another called VINTAGE & RARITIES: 333 Cool, Crazy and Hard To Find Guitar Pedals.

Want some more great intel on Frank Zappa and his legendary guitar sounds? Check out this EMEAPP article, Frank Zappa’s Guitar Amplifiers- Want to take a peek inside? This article takes a look at what makes these amps special, including a great tech write-up by Bryan Parnell.

And for the icing on the cake, here is his son, Dweezil, lighting up his father’s amps on a visit to EMEAPP in advance of his Hot Rats and Other Hot Stuff concert tour.

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Want a quick look at Keith Emerson’s Stage and Studio Gear?

The eagerly-awaited video release of the 2016 Keith Emerson tribute concert is upon us! It is appropriately titled “FANFARE FOR THE UNCOMMON MAN”.

We were asked to create a quick tour of Keith Emerson’s stage and studio gear for their pre-release event and we were glad to oblige. The online reunion ran on March 5th and was a blast!

Steve Lukather, Steve Porcaro, Jeff “Skunk” Baxter, Marc Bonilla and others got back together to announce the release of the tribute concert video that is loaded with top-notch performances from many of Keith’s friends and compadres.

You can find the tribute concert for sale below, it is worth having! The best part is that all proceeds benefit the focal dystonia research, the disease that attacked Keith Emerson.

From the Cherry Red Records website:

A new concert film and album documenting the May 2016 tribute show honouring the late Keith Emerson.

The Official Keith Emerson Tribute Concert will be available as a four-disc set featuring DVD and two CDs capturing the entire two-and-a-half-hour event and a disc of Bonus interviews.

The show featured a roster of rockers including Steve Lukather, Steve Porcaro, Eddie Jobson, Jordan Rudess,  Brian Auger, Jeff “Skunk” Baxter, Vinnie Colaiuta, Marc Bonilla, Gregg Bissonnette, CJ Vanston, Troy Luccketta, Rachel Flowers, Terje Mikkelsen, Philippe Saisse, Travis Davis, Ed Roth, Mike Wallace, Mick Mahan, Karma Auger, Rick Livingstone, Jonathan Sindelman, Joe Travers, Kae Matsumoto, Aaron Emerson, Dan Lutz, and Michael Fitzpatrick. The event also featured Emerson’s son Aaron, and members of his solo band and his Three Fates Project group.

The show, which was held at the El Rey Theatre in Los Angeles, offered a career-spanning celebration of Keith’s work, including music from ELP, The Nice, Three Fates Project and the Keith Emerson Band.

The DVD also features artist interviews, behind-the-scenes footage, tribute speeches and a gallery of rare photos provided by the Emerson estate.

George Secor- Music, Mathematics and the Miracle Temperament

Today is a year since George Secor passed on at 76 years of age, what a great opportunity to look back on his visit to EMEAPP back in 2018.

Yes, he was a focused and precise musician and mathematician, his academic work led him to discover the microtonal miracle temperament and even have a microtonal interval named after him. But face to face, George was a jovial and kind individual who really enjoyed the excitement of composing and performing music on unique instruments.

He was an accordionist, but he favored the Moschino Free Bass instruments rather than the traditional type. This allowed him more flexibility in chord structure and allowed for more comprehensive musical figures.

Secor also developed a musical notation system that allowed for the limitless microtonal script, you can see the basis of this at You can also see the symbols utilized in Sagittal as well as assigned pitches and more at

Three of this type of Scalatron exist in the world

But for us, the payoff was time spent with George on our vintage Motorola Scalatron, a synthesizer that allows the user to “play between the cracks” of the standard western 12-note octave. In fact, it is capable of dividing an octave into 1,056 notes!

Our original Motorola Scalatron

When George passed, he graciously donated his personal Motorola Scalatron to EMEAPP knowing that it will be viewed and used by many for generations, rather then ending up in a dumpster in Southern Illinois (this almost happened!).

Motorola Scalatron donated to EMEAPP by Secor

It was our honor to present George with a posthumous EMEAPPP Lifetime Achievement Award in late 2020 to acknowledge his efforts in the world of microtonal research, scale design and notation.

Enjoy this video and take some time to research George and all of his musical doings. He was a great family man and we are proud to have had the opportunity to spend some quality time with him.

Happy trails, George!

The Story of the EMEAPP ARP 2500 Modular Synthesizer


I remember the first time like it was yesterday, being face to face with an ARP 2500 modular synthesizer at the Electronic Music Education and Preservation Project near Philadelphia. Everything about the instrument was flat-out sexy, from the knob colors to the natural wood to the intriguing matrices. I had seen many pictures of a 2500, but it was so different in person.


The ARP 2500 was an analog modular synthesizer created by ARP Instruments, manufactured from 1970 through 1981. The units were costly and technically advanced challenging for the novice, only 100 or so units were created. They are truly unique and have a sound of their own.

You might be familiar with the dynamic intro to Elton John’s “Funeral For a Friend”. The epic piece was created by producer David Hentschel on an ARP 2500. You also hear it all over The Who’s album, “Who’s Next”. In addition to using it as a keyboard synth, Pete Towshend processed his guitars and keyboards through sets of modules on a number of songs.

French electronic music composer, Eliane Radigue used her ARP 2500 almost exclusively throughout her career. Synthesist Jean Michel Jarre considers the 2500 to be one of his favorite instruments. We share this in common.


Nowadays, I have the opportunity to be in the presence of this ARP 2500 on an almost daily basis as the Director of EMEAPP. With two wing cabinets on stands and fully-loaded with modules, this is truly a rare bird. Only 100 or so units were built and each was a custom order; there were no standard configurations.

We care for quite a few ARP instruments at EMEAPP. We always have a white Odyssey wired up near with a Pro Soloist, our Quadra is always at the ready. But, the ARP 2500 is the Godfather of the collection and sits on a high pedestal, figuratively and literally.

It Grows

Our ARP 2500 began with a single large cabinet synth. Years later, a second large cabinet rig was sourced, which sat atop the other for years. We lovingly called it our ARP 5000. Then our curator caught wind of an über-rare matched pair of wing cabinets with their original wooden stands. They were clean and good looking– cherry switch matrix heaven!

OUR “ARP 5000”

Then it was time to merge the beasts, to comingle the two wide-cabinets into a large center cabinet with a pair of wings. Tim Warneck was brought into the ring with the intention of assembling our beautiful monster. Our first goal was to make certain that the power supplies were in top-order, a requirement to prevent damage to the modules. Next Tim populated the wing cabinets with modules from the donor cabinet.


The good news about the 2500 is that the modules can be configured in almost any way we like. We discussed our module layout plans and Tim took action. Then, after a good clean out and inspection, the units were powered up and tested for basic function.



We have done quite a few sessions with our ARP 2500 in the last three years, beginning with the single-cabinet machine and then with the behemoth above. Some sessions were quite simple, but others were deep and complex. In any case, a lot of work goes into an ARP 2500 session, especially when it comes to planning.


Our first ARP 2500 session was with Scottish artist, Luke Fowler. We had quite a learning curve to get comfortable with matrix patching, for both audio and voltage. We had a blast getting a taste of each module, some are really unique! The session went very well, the instrument behaved nicely and was a joy to work with. Read up on Luke Fowler here.



Our next sizeable ARP 2500 session was in support of a unique project indeed, to recreate the Cylon character’s voice from the TV series, Battlestar Galactica. Joe Grandberg and Chris Dexter came to EMEAPP to discover and recreate the original synth component, derived from an ARP 2500.

Joe brought a beautiful selection of vintage gear for the session to help determine the proper sound and operation of the 2500. It took quite a bit of effort, but the outcome was worth it! Check out the entire series of the process, it’s really cool!


One sunny Philadelphia afternoon, Dina Pearlman of the Alan R. Pearlman Foundation reached out to us. She spoke about a huge video project that was underway that could benefit from some resources that we might have at our facility. Alan R. Pearlman was A. R. P. of ARP. He, along with partner David Friend and a crew of talented folks created the 2500 and many other vital instruments. The Foundation has always been of importance to us, seeing as how Alan played such an important role in synthesizer development. He was a true pioneer.

Dina indicated that video producer, Alex Ball, was nearing completion of this full-length video that does a deep-dive into the history of ARP synthesizers. He needed pictures of some rare and unique instruments, many of which we have under our roof. It was quite an effort, but we sent him dozens of images and video demos for the project.

Check out the finished product called Electromotive: The Story of Arp Instruments. You’ll see many of the images, videos and sound samples that we provided. It was a great project for EMEAPP to take on as this video will have historical and informational value for decades to come.


Another great 2500 session series was with synth pioneer, Don Slepian, who spent some quality time with the instruments when they were still in manufacture. He also had the rare opportunity to create original compositions on the famed ALLES computer, built by Bell Labs in 1979. It was fascinating to watch Don utilize individual 2500 modules similar to Pete Townshend, using a series to modify an external audio source. In the videos below, Slepian used a wooden flute and an ARP Quadra run through a series of modules, proving that the black and white keyboard certainly isn’t necessary.

Don ended up creating an outstanding series of music and videos during his sessions at EMEAPP. Keep your eyes open for a future article about Don, he has an interesting history and a huge body of work.

Don was even gracious enough to give the audience a general tour of the EMEAPP ARP 2500.



Vince Jr and I have created quite a few episodes for our Sonic Test Drive series. Here is Vince taking our ARP 2500 for a spin. In this video, he added a Roland CR-78 CompuRhythm drum machine and an ARP 1613 sequencer. We ran the rig through our vintage ARP8 mixing board as we did with Don Slepian’s session. As you’ll hear, it sounded pretty huge!


I have certainly gained an immense amount of ARP 2500 knowledge over the last three years, I am a better synth guy for it. I also truly appreciate every day that I get to walk the halls of EMEAPP and be surrounded by such a rare and valuable collection of historically significant gear like the ARP 2500. I hope my access to this instrument continues for a long time, as it fascinates and intrigues me on a continuing basis. It lights me up when I see it, I can’t wait to make amazing sounds at any opportunity in the future. Thanks, Alan R. Pearlman, David Friend and the rest of the ARP team, you did a great an amazing job.

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The TECHNOS ACXEL Resynthesizer

Recently, we took delivery of a very rare and unique synth whose perspective on sound creating would be considered unique. The Technos Acxel was created in the late 1980s and holds a strong position in the hierarchy of digital synthesis. We asked Ryan Gaston of Perfect Circuit to give us an analysis of this unique machine.

The Technos Acxel is, with little doubt, one of the most peculiar instruments I have ever encountered. Living in 2019, it feels safe to say that an instrument with its combination of qualities would be highly unlikely to emerge in this day and age. It focuses on complex and obscure synthesis methods and has a strikingly peculiar design: a design which, while quite well-suited to its rich (albeit quirky) internal architecture, would no doubt have been quite expensive to develop/produce…and thus, quite expensive for the end user. Technos was clearly driven and ambitious, sparing no expense to pursue their vision of what making music could be like—and this ambition led them to take significant risks.

The Acxel was one such risk, and one that sadly did not end with fame or fortune: approximately 35 of these instruments were produced before the company closed its doors in 1992. The name “Technos” faded into obscurity and, aside from occasional mention in historical texts (such as Mark Vail’s Vintage Synthesizers), garnered little or no continued attention. To my knowledge, the Acxel as of yet has produced no Minimoog- or OB-Xa-style chart-topping hits; it didn’t appear on stage among elaborate prog rock or synth pop groups; it didn’t find a home in any giant, acclaimed Hollywood studios. Instead, it found its way into the homes of experimental synthesists and/or collectors, and few seem to have publicly surfaced since.


Personal History with the Acxel

I was working at Perfect Circuit in Burbank, CA when I first encountered the Acxel. At that exact time, we had a host of odd and uncommon synths: a Yamaha CS-80, a Synton Fenix 1, a Waldorf Wave…all exciting things for any synth enthusiast. Among the pile of things on our testing bench, though, was an Acxel. I had never seen or heard of it before, and at first glance was not even sure that it was a musical instrument. I was tasked with learning how it worked, so as to be able to determine whether or not it was actually in functional condition.

After several days poring through manuals and testing features one by one, I gained a profound respect for the instrument. I maintain that I have yet to encounter an instrument with such a singular workflow—evidence that its creators at Technos had a very complete and sophisticated way of conceptualizing sound. It is completely distinct from the then-mainstream approaches of subtractive synthesis, sampling, and digital methods such as FM or PD, instead borrowing bits of each approach to create something unique. It quickly became one of my favorite instruments, both due to its bold vision of how sound can work, and due to its clever interface—but more on that soon.

That instrument eventually found a home with a private collector, and I accepted the fact that I would likely never see one again. But, two years later, another found its way to our shop. Happily, this instrument eventually wound up with EMEAPP: a perfect fate for something so peculiar. All too often, rare instruments such as this circulate within closed networks of collectors and eventually fade from public visibility altogether, resulting in an unintentional erasure of the fringe areas of historical instrument design. And while these boundary-pushing instruments may not be the most influential when considered in terms of widespread use, they often have powerful, unique potential to challenge the way that we think about instrument design, sound design, and music-making altogether.


The Technos Acxel Itself

The Acxel is comprised of two pieces. The Solitary, a large, rack-mountable chassis, houses the instrument’s signal processing and audio/MIDI I/O boards. In practice, the user does not interact much with the Solitary, aside from loading the OS or timbres from a 3.5″ floppy disk. Perhaps comically large by modern standards, the Solitary houses an astounding array of electronics: including basic I/O boards, the Syncards (voice cards), and depending on the exact model/configuration, the Acxelizer board itself.

The second piece, the Grapher, is the actual user interface…which is to credit for most of the Acxel’s cult reputation. The Grapher is a tablet-like control surface that allows simultaneous display and editing of all of the Acxel’s internal parameters via a series of over 2000 small LED-embedded capacitive touch plates. The Grapher’s Matrix of touch plates changes in function depending on what parameters have been selected for editing: so the Grapher is at once a menu/page-based display and a means of changing values at the touch of a finger. One can think of this as being somewhat like the Fairlight’s light pen—but it is activated simply by touch. Again, this is the way that all internal parameters are edited: envelopes, wave shapes, signal levels, and much more are all created and displayed through this absolutely sci-fi-level touch interface.

The Acxel does not provide a dedicated playing interface, though: it must be paired with a MIDI controller. This was a departure from Technos’s prior design, the 16pi, which was itself not dissimilar to an Acxel with a keyboard. Instead, users were to determine their own means of interacting with the instrument.


What is Additive Synthesis?

But the user interface is not the only peculiar thing about the Acxel: its means of sound production is also markedly uncommon. The 1980s were a bold time in instrument design; designers’ increasing reliance on digital technology for sound generation and control meant that, theoretically, almost any musical concept could be turned into an instrument. As such, some designers turned to theoretical techniques that previously might have seemed impractical—including additive synthesis.

Mainstream analog synthesizers primarily rely on subtractive synthesis—that is to say, they rely on harmonically rich oscillators (saw waves, square waves, etc.) as a sound source, then using filters to remove harmonics and emphasize certain parts of the sound spectrum in order to create interesting sounds. This is the realm of the Minimoog, ARP 2600, Oberheim SEM, and countless other classic analog synths. Additive synthesis, however, works differently: rather than using a small number of harmonically rich oscillators and a filter as building blocks, it instead typically uses a large array of sine oscillators carefully tuned to specific intervals and set to specific volumes in order to construct a sound from the ground up. This is a somewhat more atomic/elemental approach; and because a convincing additive “voice” might require dozens of oscillators and amplifiers,  additive synthesis was too impractical to implement and too tedious to program in an analog context. However, when designers began to rely on digital sound generation and digital control, such a feat was suddenly within reach.

This is the fundamental approach of the Acxel. This LED-laden oddity has a whopping 32 oscillators per voice, each with their own amplifiers. Each voice is rounded out with two-operator FM capability, two filters, and a master amplifier for voice-level volume control. Moreover, there are 64-stage envelope generators for practically every sensible destination—each oscillator in each voice has its own pitch and volume envelopes, and several voice-level envelopes control FM index, filter cutoff frequency, and overall voice amplitude. Yes—there are literally dozens of envelopes for every single voice (and the basic configuration has eight voices in total).

Of course, having this sheer number of sonic resources in one instrument is pretty jaw-dropping…but one of the most fascinating aspects of the Acxel lies in how all of these resources are controlled.


Additive Synthesis in the Acxel: the Spectrum Concept

Technos cleverly organizes the key parameters of additive synthesis into spectra in order to be able to understand the relationship between settings for each of a voice’s internal oscillators. There are several spectra: the amplitude spectrum, phase spectrum, integer spectrum, and beating spectrum. When navigating to any of the pages for editing these spectra, the touch plate LEDs illuminate in order to reflect the current settings for each oscillator in order, basically creating a touchable bar graph representing all of the settings for the selected spectrum parameter. One needs only to swipe their fingers across the Grapher’s touch plate matrix in order to alter these settings, as if it were a set of sliders or drawbars.

The amplitude spectrum defines the relative loudness of each oscillator, allowing users to emphasize or de-emphasize any overtone they desire. The phase spectrum determines the phase offset between each oscillator: the effect of the phase spectrum is more pronounced when several oscillators are tuned to the same pitch, so the effect of the phase spectrum is generally quite subtle in more complex sounds.

The integer and beating spectra work together to define the pitch of each oscillator. The integer spectrum can be thought of as a more coarse tuning value, with the beating spectrum providing finer control. The integer spectrum multiplies the base MIDI pitch by integer values from 1–32 as a means of easily tuning oscillators to precise harmonic ratios; this makes it easy to create harmonically pure, stable sounds. The beating spectrum, on the other hand, is a detuning control: it allows users to offset any oscillators’ pitches from their current “integer” values in order to access all of the inharmonic pitches between ideal overtones. This allows for much more complex, nuanced, evolving sounds…and even using these four spectra alone, a wide range of peculiar and novel sounds is available.


Dynamic Additive Synthesis

But there’s more to it than that—as I mentioned before, the Acxel is overridden with envelopes. And these aren’t your garden-variety ADSRs: they are 64-stage envelopes, each with user-definable hold and loop regions. As mentioned above, there are voice-level envelopes for controlling filter cutoff, FM index, amplitude, etc…but there are also per-oscillator envelopes specifically for controlling pitch and amplitude. Yes—there are roughly 70 envelopes per voice. Ordinarily, handling 70 envelopes would be an overwhelming and tedious feat; but as with the clever organization of spectra, Technos came up with a relatively efficient (and dare I say, almost intuitive) way of handling envelope settings.

Amplitude and pitch control in the Acxel can operate in one of two high-level modes: Fixed Additive Synthesis (FAS) and Dynamic Additive Synthesis (DAS). In FAS mode, amplitude and pitch values are determined by the spectrum values alone, but in DAS mode, the envelopes come into play. Users can switch additive synthesis modes and access envelope editing pages using the ISC (Intelligent Synthesis Cell) menu touch plates on the left of the Grapher’s touch plate matrix.

Envelopes are assigned to individual ISCs (the combination of one oscillator and amplifier) by using the Numeraline, the row of 32 touch plates immediately below the Grapher’s matrix. Once a cell has been selected for editing, its current envelope shape is displayed via the matrix LEDs: it can be re-shaped simply by swiping one’s fingers across the matrix surface. What is particularly interesting is that multiple ISCs can be selected for editing all at once—by selecting multiple ISCs via the Numeraline, it becomes easy to make broad changes in several cells at the same time. This removes much of the tedium in different implementations of additive synthesis, and makes it fairly quick to achieve complex, dynamic results.

DAS control of amplitude is fairly straightforward: it allows evolving changes in the concentration of particular overtones, providing easy access to continuously shifting spectral focus. There are two separate DAS modes related to pitch, only one of which may be used at a time: DAS-I, in which envelopes modulate the current Integer Spectrum values, and DAS-P, in which envelopes modulate the current Beating Spectrum values. DAS-I produces considerably more coarse pitch changes locked to harmonic ratios, often resulting in peculiar harmonic arpeggio-like effects. DAS-P, on the other hand, is an excellent way of introducing dynamic detuning, twisting overtones into constantly changing inharmonic ratios for sounds that shift from stable to clangorous and back again. By using intentionally-devised combinations of pitch and amplitude envelopes, the Acxel can produce remarkable variation across the course of a single note. (As a side note: in my personal experience, the Acxel excels at drawn-out, atmospheric/textural sounds…there’s simply so much possible within a single note that can too easily go unnoticed with shorter, more idiomatic “keyboard” sounds.)

As mentioned before, there are also per-voice envelopes for volume, filter cutoff, and FM index. All envelopes in the Acxel are 64 steps long, can range from hundredths of a second to half a minute, and allow the user to define a region of segments to loop when a key is held (using the Alphaline, a line of touch plates above the Matrix). What’s more, all envelopes utilize what Technos calls the Dual Envelope Concept: meaning that each envelope can continuously interpolate between two different, user-definable shapes. By using key velocity to perform this interpolation, for instance, the Acxel can be made to produce highly dynamic results which, in the best situations, can lead to combinations of character entirely impossible to predict.


The Tandem Problem & Resynthesis

The use of Spectra and the Acxel’s clever interface for editing envelopes does make for an uncommonly smooth and immediate additive synthesis experience—but it’s no secret that even this implementation is far from the ease of use of a Minimoog, for instance. Making good sounds from scratch can still take a considerable amount of time, cleverness notwithstanding.

Happily, the Acxel does offer another way of defining sounds: resynthesis. In many ways, resynthesis is the Acxel’s primary intended use case—or at least, that is what sales literature would leave one to believe. Technos saw this technique as a solution to some of the issues inherent in the then-still-maturing technique of sampling: namely, the issue they describe as The Tandem Problem.

The Tandem Problem is no doubt familiar to anyone who has used a traditional sampler. In samplers, pitch changes are often achieved by using playback rates different than the audio’s sampling rate. By playing back at rates slower than the sample rate, output sounds appear lower than the original sampled sound; by playing back at faster rates, the sound appears higher in pitch. This is great (and useful in a lot of situations!), but comes with an intrinsic, unintentional consequence: it also results in the sound being shorter as it increases in pitch, and longer as it decreases in pitch. This is the Tandem Problem.

Resynthesis is related to sampling, but a bit more complex in execution. In resynthesis, a source sound is recorded into a buffer and then analyzed (often via FFT or similar methods). The result of this analysis is a mass of information about the sound’s harmonic structure and how the loudness and pitch of its overtones change over time. The resynthesizer’s internal synthesis engine, usually comprised of a huge number of sine generators and amplifiers, interprets this analysis and utilizes it as control information, resynthesizing the sound through additive synthesis. The end result is a sound ideally quite similar to the input analyzed sound.

This has a huge number of advantages over sampling. The first is that the Tandem Problem is no longer a concern: since sounds are constructed out of banks of variable-frequency sine waves with pitch and volume contours defined by variable-duration envelopes, changing pitch doesn’t have to mean changing the duration of a sound (and vice versa). Changing pitch is instead just a matter of shifting all of the overtones by an identical musical interval (maintaining their harmonic relationship). Similarly, changing duration is just a matter of expanding or compressing all of the envelopes within a sound…pitch doesn’t have to change at all. This means that pitch and duration changes are both possible, and entirely independent of one another.


The Acxelizer

The Acxel achieves this process via the Acxelizer: a processor based on a simple AI that performs the analysis described above and assigns all of the most pertinent information within the analyzed sound to the voices’ Intelligent Synthesis Cells—ISCs, the combination of an Intelligent Digital Oscillator (IDO), Intelligent Digital Amplifier (IDA), Intelligent Pitch Envelope Generator (IPEG), and Intelligent Volume Envelope Generator (IVEG). The Acxelizer can even determine how many overtones are required to adequately reproduce a sound and “steal” resources from multiple voices to construct a single sound…which ultimately reduces polyphony, but enables the resynthesis of considerably more complex spectra, even including highly effective resynthesis of the human voice. Another interesting implication of resynthesis in this fashion is that it permits extensive manipulation of the sound, down to a much more atomic level than with pure sampling.

The Acxel maintains the same level of editing potential with resynthesized sounds as it does with purely synthesized sounds…so users can reach within a sound and modify the spectral profile, and the way it evolves over time. This is excellent for creating alien sounds from familiar sources, allowing the cadence of natural tones to influence the unfolding of otherwise impossible textures. You can quantize the natural inharmonicities in a sound to harmonic intervals; you can frequency modulate resynthesized sounds; you can accentuate weak overtones and de-emphasize strong ones. Being able to reach down to this level of detail in recorded sound is all but impossible…and this is what is meant by “Acxel”: it is an auditory pixel, the smallest unit of digital sound to which Technos provides you access.

The Acxel came with several 3.5″ floppy disks of presets: a host of synthesized and resynthesized sounds ranging from Moog-style bass to harp glissandi and loon calls. Some of these sounds are far more compelling/interesting than others…and while they are remarkable given the age of the instrument, some have “held up” better than others. Regardless, the instrument’s capabilities to synthesize complex sounds from the ground up are remarkable…and only otherwise possible at the time through similarly complex/valuable instruments such as the Synclavier.

Note: despite the name, not every Acxel necessarily contains an Acxelizer: the most affordable model at the time of production was the Acxel Stage, which could synthesize sounds from scratch or use preset “Acxelized” sounds created with another Acxel. British magazine Music Technology reported in their March 1988 issue that the Acxel Stage cost 8500GBP at that time. The Starter Studio, a basic system with Acxelizer, cost 14,545GBP; and the “top of range” system, complete with Acxelizer and maximum number of voices ran for 37,930GBP. EMEAPP’s Acxel is what, according to sales literature, was called the Pro Studio model, containing an Acxelizer and one Syncard (for a maximum of eight voice polyphony), with both a mixed signal output and individual outputs for each voice.


There is so much more to the Acxel. It is multitimbral—individual voices can be split, layered, or operate on completely separate MIDI channels. It has an analog lowpass filter for each voice, and a Variable Integer Pass (VIP) digital filter which allows you to hone in on specific Integers; there are LFOs (including an Intelligent LFO for translating vibrato in resynthesized sounds); you can even change the wave shape of the oscillators used for resynthesis…the list goes on.

But after getting to know the Acxel, it becomes apparent that it was never quite finished. Several front-panel controls do nothing; several sections of the user manual refer to “reserved,” incomplete functions; redundant editing pages make it feel as if features were planned, but never quite made it into existence. It is clear that Technos had big plans for where the Acxel was heading…and despite all they accomplished, it doesn’t seem as if it ever got as far as they might have liked. Later iterations were planned, but sadly none ever came to fruition.

Despite this, working with the Acxel is an amazing and rare treat…one that I hope I’ll have again in the future. It is a true rarity, and an ideal packaging of what was great about instrument design in the 1980s: designers were bold, and truly sought to create instruments unlike anything else that had ever existed. And, in this case more so than many, they succeeded.


One way for EMEAPP to advance its mission is to offer assistance and encouragement to others who share our goals. So, we’re proud to have played a role in the birth of a big, beautiful new book about vintage keyboards: Classic Keys: Keyboard Sounds That Launched Rock Music, by Alan Lenhoff and David Robertson. You can learn about this book here:



This is the keepsake book many of us have dreamed about: A beautifully photographed and authoritative book that celebrates the great rock keyboards of the 1950s through the early 1980s: Hammond organs, Rhodes and Wurlitzer electric pianos, the Hohner Clavinet and Pianet, the Mellotron, the Yamaha CP70, Vox and Farfisa combo organs, Moog synthesizers and many more. It’s great “eye candy,” but also tells a deep story, putting these instruments in the context of the technological, social and musical trends that made them possible, and made these instruments the centerpiece of so many great bands. It follows the path from the time when a rock keyboard was whatever down-on-its-luck piano a band found waiting for them in a music venue to its evolution into a portable digital orchestra.


We helped make Classic Keys happen in two ways: We provided a grant to help offset the considerable publishing costs of such an ambitious book. We also provided the authors with studio photographs of instruments in our collection. As Lenhoff says, “The economics of publishing make it extremely difficult to publish a large-format, hardcover book of more than 400 pages when it’s aimed at a niche market. The grant we got from EMEAPP helped ensure that we never had to compromise on the quality of the book. It’s a first-class gift book in every way.”


Almost all of the beautiful studio photography of instruments in the book was done by Robertson, who is an Australian industrial designer, commercial photographer and design historian. That created a challenge. “Some of the instruments that were photographed for us by EMEAPP were either rare or otherwise difficult for me to find in Australia—especially in the fine condition we needed so the instruments would look like they did when they were new,” Robertson says. “EMEAPP’s photos helped us fill in some important holes in the book.”



Lenhoff, an American journalist and media executive, and EMEAPP founder Vince Pupillo Sr. began talking about the book about five years ago, when Lenhoff interviewed Vince to capture the story of EMEAPP for the book. Several years later, they began discussing how EMEAPP might participate in the project. “EMEAPP’s support has been a real difference-maker for us, and for the readers,” Lenhoff says. “We couldn’t have had a more appropriate partner.”



The book has attracted enthusiastic praise from such A-list players as Rick Wakeman (Yes), Donald Fagen (Steely Dan), Chuck Leavell (Allman Brothers and musical director of The Rolling Stones) and Steve Nieve (Elvis Costello). As Wakeman says: “The story of keyboard development, the people who built them, and the part they played in our musical history has never been fully told up until now. This book is a must for all who love keyboards and their history and indeed, music in general. It should be on every
music lover’s bookshelf.”

The Birth of Keith Emerson’s Moog

50 years ago from the day of this writing, Herb Deutsch, Chris Swansen along with a handful of other dedicated performers and synth-minded people, assembled a concert on Moog synthesizers in front of 4,000 thrilled fans at The Museum of Modern Art in New York City. Bob Moog and his team created four modular synthesizers for this very well received, unique and innovative performance.

Jazz In the Garden Moog concert announcement

Keith Emerson, who played keys in The Nice at the time, reached out to Bob Moog and was able to acquire one of these modular synths for his own musical explorations. This began a lifelong relationship that ran deep on so many levels.

Over the decades, the gigantic sound of this iconic instrument found its way into the hands of eager fans on ELP songs like From The Beginning, Tarkus, Toccata, Tank, Karn Evil 9 and the favorite of so many, Lucky Man.

Keith Emerson’s Moog modular as it stands today

Keith’s Moog synth traveled the globe with Emerson, Lake and Palmer. Keith worked with Bob and his team to update and upgrade the instrument to meet Keith’s on-stage and studio requirements. The synth would get hammered from the touring and Keith’s techs and the Moog crew chipped in to keep it working the best they could.

In 2011, as the instrument fell into disrepair, Keith decided to have this highly customized instrument rebuilt. Technicians Gene Stopp and Brian Kehew worked on it feverishly, the result was a stable and fully-working synth, capable of handling anything that Keith could throw at it.

After Keith’s untimely passing, his extended family determined that “the world’s most famous synthesizer” should end up in the hands of the Electronic Music Education and Preservation Project. Through the guidance of Michelle Moog-Koussa of the Bob Moog Foundation, they understood that our stewardship would harvest great substance from this instrument and that we would share it with the whole world, judiciously and with sensitivity. They also understood that what is most important to us is Keith Emerson’s musical legacy and that his Moog synthesizer is really a living and breathing symbolic object of this legacy.

In April of 2019, we brought Keith’s Moog synth to the Metropolitan Museum of Art in New York City to play a part in their “Instruments That Rock” exhibit. At the time of this writing, more than half a million visitors and fans got a close-up view of the Moog and two of Keith’s Hammond organs.

EMEAPP Exhibit2
Keith’s gear on display at The MET in New York

As his beloved instrument turns 50 years old, we celebrate the Jazz In the Garden concert where it all began. We tip our hats to Bob Moog, Herb Deutsch, Chris Swansen and the whole crew who made this milestone performance happen. We also tip our hats to Gene Stopp, Brian Kehew and all the folks involved in getting this iconic instrument back on its feet.

We look forward to its homecoming with great anticipation. 🙂 

 Here is a wonderful article written by Lauren Rosati of the Museum of Modern Art that tells the story of this very important performance.

View of the concert performed by Robert Moog and the Moog Synthesizer, part of the Jazz in the Garden series, The Museum of Modern Art, August 28, 1969. Photographer: Peter Moore. Photographic Archive. The Museum of Modern Art Archives, New York

The exhibition Making Music Modern: Design for Ear and Eye explores the ways in which sound technologies have shaped the way we listen to musical culture. Highlighting both technical innovation and design aesthetics, the exhibition includes a number of modern instruments, including a Yamaha Portatone Keyboard and a Fender Stratocaster electric guitar. While MoMA was the first museum in the world to collect such objects, beginning in 1932, it also pioneered the live presentation of some new music technologies. For instance, Russian émigré Vladimir Ussachevsky performed the first tape-music concert in the United States at MoMA in October 1952. And though the Museum’s collection does not include a synthesizer, it presented the famed Moog synthesizer as a live performance instrument for the very first time on August 28, 1969, changing the course of music history and influencing decades of future instrument design.

Program for Robert Moog and the Moog Synthesizer Concert-Demonstration, part of the Jazz in the Garden, series, The Museum of Modern Art,  August 28, 1969. Public Information Records, II.B.708. The Museum Modern Art Archives, New York

Described by the press as “alien” and like “a fox let loose in a chicken shack,” the sounds of the Moog synthesizer filled MoMA’s Sculpture Garden during the final event of the 1969 Jazz in the Garden concert series. Critic Greer Johnson wrote that “the ‘demonstration’ of Robert Moog’s synthesizer at MoMA…had all the musical persuasiveness of lobotomized Hal in 2001: A Space Odyssey singing ‘On A Bicycle Built For Two.’” Bob Moog was surely an unlikely act to close out the series, which also included performances by the Muddy Waters Blues Band and the Bob Patterson Gospel Singers, as well as a variety of more traditional blues and jazz groups.Unwieldy, complicated to operate, and capable of playing only one note at a time, the Moog Modular Synthesizer was initially relegated to the recording studio. It consisted of oscillators, filter banks, reverb units, voltage control, mixers, and other modules in a single console connected by patch cords and controlled by an organ-like keyboard. A prototype was released in August 1964 and first appeared on a musical track later that year, when Herb Deutsch composed “Jazz Images: A Worksong and Blues.” Songs by the Rolling Stones, Monkees, Beatles, and Byrds helped to popularize the instrument, and by 1969 “Moog” was synonymous with “synthesizer.” Yet, despite demands from his sales representatives and session musicians, Moog had not yet devised a synthesizer for live concert events. An invitation from MoMA provided the push he needed. Impelled to produce an ensemble of real-time, portable systems for the event, Moog designed four modular synthesizers that operated from a new pre-set box, which allowed the musicians to activate six basic sounds at the push of a button and adjust settings in advance. The instruments—a basic Moog, a bass synthesizer, a polyphonic keyboard synthesizer, and a percussion synthesizer—were completed the day before the event.

Herb Deutsche performs at on the Moog Synthesizer during the Jazz in the Garden program, The Museum of Modern Art, August 28, 1969. Photographer: Peter Moore. Photographic Archive. The Museum of Modern Art Archives, New York

Live at MoMA, 1969. Printed in Trevor Pinch and Frank Trocco, Analog Days (Cambridge, MA: Harvard University Press, 2002), p. 189

On the night of the concert, roughly 4,000 people—quadruple the attendance of previous events—jammed into MoMA’s Sculpture Garden, climbing onto sculptures and into trees to get a better view. A quartet led by Herb Deutsch opened the concert with a performance of electronic bebop jazz that sounded “wavery and hollow, as though coming from outer space.” According to a review in Audio magazine, “Following a few preparatory bleeps, hoots, and grunts, the musicians swung into a pleasantly melodic four-movement suite…. At various times, sounds were reminiscent of trumpet, flute, saxophone, harpsichord, accordion and several varieties of drum, but, in general, one was content to listen to the music on its own terms, without trying to draw any comparisons with conventional instrumentation.” Pianist Chris Swansen next led his quartet in a thickly orchestrated rendition of “Ooh Baby” by the Free Spirits, until a fuse blew and a reveler inadvertently pulled the power plug for the sound system, abruptly stopping the performance. Despite these technical difficulties, the significance of the event was not lost on critics, who praised this historic concert at MoMA for launching the use of the synthesizer as a live performance instrument, for popularizing the Moog Modular system, and for “making music modern.”

The author wishes to thank curator Juliet Kinchin and Albert Glinsky, whose book Theremin: Ether Music and Espionage provided source material for this post.

Frank Zappa’s Guitar Amplifiers- Want to take a peek inside?

Frank Zappa was many things to many people: an outspoken critic, a cunning songwriter, a skilled performer, a voice for free speech in music, a family member. Our focus today is on Frank Zappa, the guitarist and sculptor of some amazing guitar tones across his storied career.

Image courtesy of Zappa Family Trust

Frank knew a lot about guitar tone, he had a sharp focus on how to achieve the sound he was seeking.  From his days with Captain Beefheart and the Mothers of Invention through decades of albums and touring, his guitar tones were always bespoke and articulate. His effects and amplifier system grew and changed over the years to accommodate his broad musical landscape and thirst for the perfect sound. His application of studio effects was also ever-changing, his “Ma Bell” effects rack was refrigerator-sized and loaded with tons of studio-grade gear that he would use to create his unique sound palette.

Zappa Amps4. (3 of 4)
Frank Zappa’s Vox and Marshall amplifiers

He used a lot of gear, but one thing stayed true from the mid-1970s onward: Frank loved his Vox Super Beatle system tied-in with two Marshall half-stacks. One head was a Marshall Major, the other was a 100 watt JMP.  Frank used the Vox Super Beatle in his earlier years, the Marshalls began their duty beginning in the early 1970s. You can see this rig in action in the video below, shot at The Palladium in New York in 1977.

We had to make certain that this rig was operating properly for an upcoming recording session, so we removed this venerable artifact from the exhibit and rolled it into the workshop for a good look and road test. The goal of the recording session was to collect impulse responses through Frank Zappa’s rig, giving his son, Dweezil, the opportunity to recreate Frank’s tone live on stage. This Vox and Marshall rig was a huge part of his sound and Dweezil wanted to bring it to the world.

Frank Zappa’s rig in our workshop

We determined that the whole rig was in very good condition considering its age and touring history. A few of the JBL K120 12” alnico drivers were blown, so we replaced them with other K120s from our Zappa collection, tightened up some screws, and the cabinets were good to go. The heads required some special focus, but we safely fired them up and looked forward to hearing the outcome.

Aaaaand the outcome was freaking awesome!

Dweezil stepped up and took each of the amp rigs for a spin, the wall of sound they created sent an off-the-charts energy through our live room. Each amp sounded totally different but equally awesome, Frank’s guitar sound must’ve been epic in a live scenario. Check out the video clip below, you can get a good idea of how it sounded!

The recording session went off without a hitch, it was a top-shelf studio geekfest. Fractal Audio Systems was in the house to help dial-in the tones and collect the impulse responses. We ended up using Freddie Mercury’s Neumann U67 tube mic through a Helios mic pre/eq from the early Rollings Stones Mobile Studio. The session went so well that Dweezil was able to use the impulse responses to bring Frank’s “Hot Rats” album to his live audiences, complete with a tone befitting Frank himself.

We invited amp-guy Bryan Parnell of Retro Sound Works to take a deep dive inside Frank’s guitar system and give us a technical analysis. He took a good look at the gear and submitted this report.

Zappa’s unique live tone consisted of a combination of speakers, amplifiers, unconventional settings, and ultimately skill. Taking a somewhat deeper technical look into his amplification, we can see a few things that might have contributed to this.


For starters, we cannot help but gravitate towards the Marshall Major. This amp, with the 200 Watt Lead “Canada” circuit, has a test date of December 9th, 1972. Interestingly enough, the amp has newer Marshall 100 watt JMP spec transformers installed with new mounts, while retaining its massive GE 6550A output tubes, just as later US-spec 100 Watt JMP’s would have had. This may have been due to failure of the notoriously fragile original transformers, or in an effort to better match the sound output of his 1971 100 Watt JMP. The preamp was fitted with Ruby 12AX7A’s, known for low-microphonics. Marked settings can be seen on the faceplate in red marker, showing some unconventional choices such as the Bass control being set to 10, along with conservative volume settings of 3 and 4 for each respective control.


The large original power supply choke was retained, as was the original impedance selector switch. Some of the filter capacitors have been changed. All tube sockets are US-made ceramic units, possibly to prevent arcing. One externally visible mod is what appears to be a pre-phase-inverter “master gain”, functioning as a somewhat crude master-volume, allowing for strictly preamp distortion, without driving the phase inverter. This results in a sharper breakup, with less warmth, and less even-order harmonics, unlike the sound of cranked up power tubes. If you have played a mid-70’s master-volume equipped Fender, you are familiar with pre-phase-inverter master-volume circuits.


Accompanying the Major, we find an early 1971 Marshall JMP MK2 100W Lead amp. This amp is mostly original, with the exception of Czech (JJ or Tesla produced) Ruby EL34 power tubes, Ruby 12AX7A, and a “Master Gain” installed in 1978, as noted on the service tag on top of the amp. The amp appears to retain its original filter capacitors, and also shows two sets of settings marked on the faceplate. One of these shows once again the Bass control set to 10, and a high setting of 8 on the Volume I control.


Both of these heads were run through a variety of cabinets, including two pre-1969 Marshall 1960 cabinets front-clip-loaded with high-efficiency alnico-magnet JBL K120 drivers. Not to mention the cabinets were recovered with iconic red carpet, with the grills replaced with expanded mesh, likely to protect the speakers, as the cabinets were never cased. The JBL K120 was one of the loudest musical instrument speakers available in its day, and had extended frequency response. They also were easily capable of handling the hundreds of watts a cranked JMP can put out.


Finally, we encounter the oddball in the room, a solid-state Vox Super Reverb Beatle amplifier, with its accompanying 4×12. This amplifier shows no signs of modification, besides a quarter-inch input jack located on the right side of the control panel, with no indicated function. The amplifier has relatively conventional control settings, and features various affects, blendable reverb which is channel assignable, and a frequency generator for tuning use. 

Its accompanying cabinet features four more JBL J120’s, in two ported 2×12 sections. Each section is relatively large for a 2×12, and the rectangular port is formed by where a tweeter would have once sat. The rear of the cabinets are lined with 1 inch dense insulation. I can only imagine this cabinet has a deep percussive tone, with plenty of bass and treble to spare. It has its original trolly cart, and is also covered in red carpet.

You can find more intel on Bryan Parnell at