RadioShack’s Neglected Moog: Exploring the Realistic Concertmate MG-1

The Realistic Concertmate MG-1 is one of the lesser-known Moog creations, released in 1981 and branded under RadioShack’s Realistic name. It was created by Paul Schreiber from Tandy Systems Design on the RadioShack side and David Luce from Moog Music.

Luce joined Moog in the early 1970s as the Head of Engineering under Bob Moog and is most known for his work creating the famous PolyMoog. In 1977, Moog Music was bought out by Norlin. When Moog’s founder, Bob Moog, left the company, Luce was promoted to president.

Luce had demoed a prototype monosynth for RadioShack’s Bernie Appel at an internal trade show, generating interest in the idea of an inexpensive synthesizer branded under the Realistic name. Schreiber was given the prototype and told to work out a design that would fit within RadioShack’s requirements.

In an interesting and colorful email account from the Analogue Heaven list in 1999, Paul Schreiber wrote that the MG-1 was “more Electronotes than Moog," referencing the newsletter that started in the early 1970s and contained many circuit ideas, schematics, and applications for synthesizer design.

Schreiber noted that he had to design the synth with an incredibly high profit margin for RadioShack, which meant using cheaper components (supplied by Tandy Corp) than Moog normally used at the time. RadioShack’s market was the home consumer, which meant that the MG-1 was to have RCA jacks (instead of the more professional quarter-inch connectors) and a simple polyphonic square wave organ. RadioShack advertised that the MG-1 could be patched into a HiFi to play along with the user’s favorite tunes.

The MG-1's Architecture

The architecture of the MG-1’s main synth engine is comprised of two core voltage-controlled oscillators (VCOs) capable of both saw or square/pulse waveforms, a 24dB/oct resonant low-pass Moog ladder filter, a mixer section, a contour generator with attack/release or attack/sustain/release modes, and a low-frequency oscillator (LFO) with square/triangle/random modes.

The filter does have some slight differences to the classic MiniMoog filter but still offers the characteristic Moog sound. The oscillators can be hard-synced or you can tune OSC2 up or down almost a full octave. A common mod is a resistor change to get that full octave range. The VCO square wave outputs are set to full 50% duty cycle square on OSC1 and narrow pulse for OSC2.

Marc Doty’s excellent series of videos on the MG-1

The contour generator — or envelop — can be routed to the filter cutoff or can control the CA3080 based voltage controlled amplifier (VCA), and the LFO can be routed to either the filter cutoff or pitch via the modulation mixer. The monophonic keyboard is high note priority with a portamento circuit.

Moog's 1984 Product Catalog. Photo via Retro Synth Ads.

In the audio mixer section, you will find sliders to mix OSC1, OSC2, a “white noise" source, a ring modulated signal from OSC1/2 called “Bell Tone" and a quirky “Polyphony" signal that is a fully polyphonic square wave organ. The poly signal technically makes the MG-1 a paraphonic synth, in that all notes go into a single filter and VCA. The noise source is actually based off of a primitive digital chip and has a reputation for being somewhat repetitive. There are several modifications that can be done to add a more robust analog noise source to the synth.

According to Paul Schrieber, RadioShack had an exclusive option on the design of the MG-1 for 18 months. When it expired, Moog made a few changes to the circuit, removing the polyphonic organ and ring modulator and added pitch bend and mod wheels to create the Moog Rogue. The same Rogue circuit is also found in the Taurus II bass pedals that Moog also released at the same time. Both are pictured in the ad below alongside the Source and Memorymoog.

Modding the MG-1

The MG-1 is a relatively simple synth that sports a few odd extra features but can be greatly expanded with modifications. The most common of these is the addition of an external audio input to the filter — something the Rogue added and is found on just about every other Moog synthesizer ever produced.

The ability to process external sounds such as guitars, vocals, or other synthesizers through the famous Moog filter is still something users look for, and Moog Music (as well as many other manufacturers) include filter inputs in their modern synths.

A modded MG-1

There are also several kits that allow users to add MIDI control to their MG-1. The Synhouse MIDIJack is one that is easy to install and has specific instructions for the MG-1. There is a fantastic thread on the Moog Music forum that documents in detail a comprehensive list of modifications.

One of the functional differences between the MG-1 and Rogue is the ability to alter the pitch of VCO2 only, which, while in sync mode, allows for dramatic sounding sync sweeps. Another very useful mod often added to these synths is the switch for each oscillator to drop the pitch an octave lower. This puts the MG-1 into the same pitch range as the Taurus bass pedals and turns it into an even more capable bass synthesizer.

The only major problem to consider when looking to buy an MG-1 today is due to the infamous black foam that was added as a dust protection measure under the front panel. Unfortunately, the chemical makeup of that foam causes it to become a large, sticky mess after a few decades, potentially ruining switches and sliders.

But with a lot of Q-tips, isopropyl rubbing alcohol, and hours of time, the foam can be cleaned from the synth and the components can often be restored. There are also several sellers on the internet that offer new replacement slider and switch kits for the MG-1 and Rogue. Most of the rarer chips used in the MG-1s design are still relatively inexpensive and can be found from several synthesizer repair specialists.

Under the hood of an MG-1

Modern Alternatives

While the MG-1 is still relatively easy to find for decent prices, the recent explosion of inexpensive modern analogs offers a lot of comparable options.

The Korg Monologue, for example, offers a similar featureset as far as tone generation, though with the addition of PWM and triangle waves as VCO waveform options. It also sports modern additions such as MIDI control, a sequencer and microtonal tuning. Novation’s Bass Station II is also an extremely capable and inexpensive monosynth with a fully featured arpeggiator, two LFOs, and a healthy amount of modulation routing options.

Ultimately, what makes any Moog a Moog (or Realistic Moog) is the famed ladder filter. The closest modern synth in the $400 to $600 price range with that sound comes, of course, from the source.

The Moog Minitaur is based on the Taurus family of bass synthesizers — particularly the Taurus II, which was based on the Moog Rogue/MG-1. The Minitaur sports a true 24dB/oct Moog ladder filter and adds two full ADSRs, more waveforms than its older relatives, plus modern MIDI control and presets.

While we now live in an amazing time with many new analog synthesizer options, the Realistic MG-1 still holds its own with beefy VCOs, thick Moog filter, and unique “poly" section. It has been used by tons of groups, from Peter Gabriel to 808 State to Questlove. The MG-1 is a bread-and-butter synth with a simple yet versatile architecture that sits well in any mix and can kick out some serious bass.


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