Ken Schaffer in his shop in the late 1970s.

In 1975 American inventor Ken Schaffer created the first dependable, beautiful sounding wireless system for electric guitar and bass. Little did he know he was also creating a circuit that would transform the sound of rock and roll.

The original Schaffer-Vega Diversity System (SVDS) was the first reliably working and beautifully sounding wireless system for musicians or, in general, stage performers. Other wireless microphone systems pre-dated the SVDS, but never became widely adopted because even the best of them lacked reliability (fade-outs, police and taxi dispatch calls!) and their sound was nothing to cherish, especially at high decibel rock n’ roll sound levels. This inspired genius inventor Ken Schaffer to add his own secret sauce and the Schaffer-Vega was born.

This unit changed the way Angus Young sounded and played.

The first prototypes saw light in 1976 and in 1977, full production was running. Many incredibly famous performers bought one (or two! Pink Floyd 20!) – at the time extremely expensive. The SVDS was actually used well beyond 1981 (year of cessation of production), as it was a very well built unit. In mid-2014, three still-perfectly working units were cloned – only their audio circuitry was – to recreate as faithfully as possible the original sound of the Schaffer-Vega Diversity System.

Schaffer’s design incorporated ingenious pre-processing circuits to preserve the integrity of the wireless signal. Notably, a mirror-image paired compressor and expander increased the radio circuit’s dynamic range to over 100 dB, 35 dB greater than the theoretical maximum that could otherwise previously be achieved within the bandwidth limits covering wireless systems by the US FCC.

Beyond the staging freedom afforded by Schaffer’s wireless, many A-list players discovered something unintended: the sonic result was pure magic! The wireless design’s unique preprocessing enriched their signal with copious amounts of harmonic content unlike anything they’d ever heard. News traveled fast. Schaffer’s wireless units became the system of choice for nearly every major artist of the mid-70s to mid-80s.

Schaffer ceased production of the Schaffer-Vega Diversity System in 1982 to pursue other interests. Soon, new, stricter FCC regulations on wireless specifications prohibited fully-analog wireless systems of its caliber from being used. SVDS artists – including AC/DC – were forced to move on… the legendary “Schaffer Sound” slipped into obscurity.

AC/DC, Aerosmith, America, Bay City Rollers, Beach Boys, Billy Joel, Black Sabbath, Blondie, Bob Seger, Bob Weir, Bob Welch, Bootsy Collins, Boston, Bruce Springsteen (Clarence Clemons, Steve Van Zandt), Chic (Nile Rodgers), Derringer, Earth Wind & Fire, Electric Light Orchestra, Elvin Bishop, Fleetwood Mac, Foghat, Foreigner, Frank Zappa, Heart, Heatwave, Janis Ian, Johnny Guitar Watson, Kansas, Kiss, L.T.D., Mahogany Rush, Mandre, Nektar, Pat Travers, Peter Frampton, Peter Gabriel, Pink Floyd, Randy Bachman, Rolling Stones, Rufus, Stephen Stills, Steve Miller, Styx, A Taste of Honey, The 5th Dimension, The Grateful Dead, Thin Lizzy, Tom Petty, Todd Rundgren, Van Halen, Yes, ZZ Top.

If one of your heroes is in this list, we recommend checking the period of time going between 1977 and 1981: likely, they were playing with a Schaffer-Vega Diversity System. There were way more than these names, yet only a total of about 1000 units were ever manufactured.


Across the world, in Rome, renowned AC/DC aficionado Fil “SoloDallas” Olivieri had been obsessed by Angus Young’s signature tone for more than 30 years. In pursuit of that sound for that long, Olivieri had bought and duplicated every piece of equipment Angus was known to use. But something was missing…

ANGUS YOUNG GUITAR PLAYER 1984 SCHAFFER WIRELESSFil "SoloDallas" playing his Gibson SG Guitar, with AC/DC shirt and Star Wars StormtroopersEventually, he happened onto a 1984 interview with Angus Young in Guitar Player magazine (“Angus Young: Seriously”, Guitar Player, February 1984). A question was asked about the recording of AC/DC’s iconic Back in Black album: “Do you use any effects?” Young’s reply was “I just have a Schaffer-Vega wireless system.” That next month, in Guitar World Magazine, he elaborated: “Yeah, I use the Schaffer-Vega. I’ve been using that since ’77. On the receiver you’ve got like a monitor switch you can boost the signal and in the transmitter you’ve got the same sort of thing. You can really give a guitar hell with ‘em. I have used the remote in the studio and it worked really good.

What? Why had Olivieri never heard mention of this before? He scoured the globe trying to find one of these elusive 40 year old units. (Only 1000-odd were ever made.)

What could be there in a wireless system that would cause Angus Young to use it even in the studio, just feet from his amps? It may sound sort of strange that a wireless system may be worthy of just an audio circuitry replication. The Schaffer-Vega Diversity System was used by many artists of the magic era of the 1970s, even in the studio. It is really the case with Angus, who began using it from 1977 to at least 1984 (documented), in the studio, recording with it all the solos and overdubbing some rhythm parts of Powerage, Highway To Hell, Back in Black, For Those About To Rock and Flick Of The Switch.

What could be there in a wireless system that would have caused Angus Young to use it even in the studio, just feet from his amps?

The Missing Link

The Schaffer-Vega Diversity System (SVDS) had already succeeded in its raison d’être: revolutionizing rock ‘n roll staging. Less known is the fact that many SVDS users took their units into the studio with them and recorded with it. The Schaffer-Vega system introduced a new twist to a process called “companding.” Angus used the SVDS’ proprietary processing and companding to shape his sound and create his unmistakable signature.

Not without some hesitation, Fil finally reached Ken Schaffer – pleading for Schaffer’s help in getting his hands on one of these magical units. Awestruck by Fil’s 30 year dedication and perseverance, Ken’s last two remaining “souvenir” units were on their way from the back of his closet to a “better home,” Fil’s, in Rome.

Olivieri:Finally getting these units was a dream come true for me, as that sound had been haunting me almost all of my life. Indeed, once the Schaffer-Vega was in connected, there, for the first time in 30 years, were those pure tones sought after by everyone. Schaffer’s system was the secret ingredient in creating these sounds.

Moments after Fil plugged one of his numerous Gibson SG’s into the 37 year old SVDS transmitter, ran the receiver into his Plexi… Instant Angus!

It took only a few demos before the 15,000 member SoloDallas blog’s community of tone-hunters began scrambling to get one of these magical units. It was then that Fil asked Schaffer to condone his producing a replica – an audio replica, not a wireless – of the SVDS to be used for those – like himself – in love with that iconic sound. A team of electrical engineers in Rome and Vienna were retained to retroengineer the SVDS – requiring, too, a worldwide search to procure components that had been discontinued decades earlier. Early prototypes of the Replica were introduced, quietly at NAMM, in January, 2014, certification completed, and production begun in Vienna in March, and fulfillment to SoloDallas blog preorders commenced in May.

The ‘Gold Tag’

The Schaffer Replica

The very first version of the Schaffer Replica, the Gold Tag, was limited to only 100 units and had a brass plate with Ken Schaffer’s signature and the serial number. Further 50 units were manufactured later due to demand, but without the tag.

Constructed with through-hole components, it was the ‘premium’ version of the Replica. The enclosure was inspired by the original SVDS ’63EX’ receiver, with all the LEDs and VU meter.

Recipient of unit #1 was Angus himself, who used it throughout “Rock or Bust,” AC/DC’s first album in eight years. He’d rediscovered the secret to the best tone he’d ever had!

Angus got his sound back.

In fact, he liked it so much he has been using it on tour ever since, as seen on Premier Guitar’s AC/DC Rig Rundown.

Angus Young & Ken Schaffer at the NYC Palladium, 24th of August 1977, as the first Schaffer-Vega Diversity System was delivered to AC/DC.

Ladies & Gentlemen… 37 years later, the same two folks doing quite the same thing; AC/DC “Rock or Bust” recording sessions, Vancouver, BC.

Keep in mind that AC/DC’s Back in Black is one of the best-selling albums of all time. Much of the lead guitar tone of Angus Young from that magic era is due to the Schaffer-Vega. The SVDS sported a clean boost, a compressor and an expander (companding), and a optical limiter in its audio circuitry, allowing it to further overdrive the amplifiers and add a unique signature to the sound. As with all guitar effects or sound effects in general in the known universe, some will like it and some won’t. We have tested the original Schaffer-Vega and its Replica extensively for two years and published many videos with it.

The Schaffer Replica Pedal

The second iteration of the Replica was a much more affordable and user friendly unit – the pedal version. Surface mount technology (SMD) allowed for a much more compact product while still retaining the same sound of the Gold Tag edition.

It was a success, seling well over thousands of units and amassing many awards and positive reviews.

The early Pedal and Gold Tag

Scores of the Replicas’ initial users found that both versions of the Replica indeed contributed the SVDS’s legendary character through a wide variety of amplifiers – not only tube, but also cheap solid state – and even emulation software. Its signature tone still makes the difference, being recognizable as that sound: a definitive replication of the audio effect of the original SVDS.

Nothing is new…

G93R3394 (1)

…except what has been forgotten.

And the story doesn’t end here.

Many big names of the music industry also added the Schaffer tone to their setup. The Replica proved to be not just a tool for achieving the Back in Black guitar sound, but also was found to work excellently in a number of different musical styles and applications. Not surprising, since the SVDS had to work well on multiple instruments (bass, guitar, miked strings, brass, etc.)

But the overwhelming success prompted us to step up our game to keep up with the demand.

The decision was made to move production to the United States of America.

Being true to our isolated obsessive nature (term coined by The Police’s Sting to describe a handful of his friends, notably Ken Schaffer), we couldn’t rest until we made sure that our products captured the very essence of the original SVDS. While our first attempt had been extremely successful, a second reverse-engineering of the Schaffer-Vega was in order now that we truly understood the potential of this forgotten piece of kit. Nothing less than perfection would be accepted.

The EX Tower


The Schaffer Replica® EX Tower is the result of this recent painstaking reverse-engineering. Several new features were added in order to offer maximum audio quality and flexibility.

The most important new feature is a vintage design analog limiter derived from the opto-isolator found in the original TX10 transmitter. Previously overlooked in our first iterations of the Replica, this component delivers incredible dynamics and touch sensitivity.

The enclosure was also completely redesigned and now is an exact reproduction of the ’63EX’ receiver. It comes in two versions: Classic or Blue.



The SoloDallas Storm® is the latest evolution of our product line. Derived directly from our latest Schaffer Replica EX Tower,  this particular design of our product line delivers the same strong character as its predecessor, the Schaffer Replica Pedal, in a different – more market standard – package, updating and even enhancing previously seen and heard features.

Smaller, powered by standard 9v power supply or battery, the Storm® was designed to suit the practical needs of gigging musicians and bedroom rockers alike.

It features the same vintage design analog limiter of the EX Tower.

The Schaffer tone will now fit into your pedalboard along with all your other favorite effects without any compromise.

The circuit that transformed the sound of rock and roll is back to do it all over… Again.

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30th Street Guitars – New York, NY
Ludlow Guitars – New York, NY
Rudy’s Music Shop – New York, NY
The Amp House – Scottsboro, AL
Kenny’s Music – Dana Point, CA
The Amp Shop – Sherman Oaks, CA
Vision Guitar – San Jose, CA
Music Gear Guys – Denver, CO
Dan’s Guitars – Honolulu, HI
Up Front Guitars – Franklin, MA
Sixx Gun Music – Saugus, MA
Memphis Backline – Memphis, TN
British Audio – Nashville, TN
Carter Vintage Guitars – Nashville, TN
Austin Guitar House – Austin, TX
The Guitar Sanctuary – McKinney, TX


Gosia Guitars – Lommel, Belgium
Diffusion Audio – Québec, Canada
Electric Mojo Guitars – Quebec, Canada
Guitar Guitar – UK
tonetheory.co.uk – UK
Henri Polizzi – France
440hz.it – Italy
Merlin Guitars – Rome, Italy
YourMusic – Rome, Italy
Thomann – Germany
Miyaji Imports – Tokyo, Japan
Ikebe Guitars – Tokyo, Japan