by Joey Swails
The Gleeman Pentaphonic was introduced in 1981 by the Gleeman company,
a partnership of two brothers, Bob and Al Gleeman. They were based (in
the grand old Silicon Valley tradition) in their garage in Mountain
I met Bob Gleeman at the 1982 AES show in Anaheim, while I worked for
Don Wehr’s Music City in San Francisco. I was blown away by the
Pentaphonic’s sound; Bob came around the store a soon after, and we
became the first authorized Gleeman dealer.
The story goes that the Pentaphonic came about when Bob decided that he
wanted a synthesizer like a Prophet-5, but smaller and more portable.
His “smarter brother” Al, a computer hardware designer, basically
designed the synth from the ground up, working from his brother’s
description of what a polyphonic synthesizer should do.
It was in actually a digital/analog hybrid — the filters and amps were
based on the same Curtis chips that were used in the Prophet, ARP and
Octave machines. The oscillators were digital, as were the ADSRs. The
machine was based on the Intel 80186 microprocessor, which was very
advanced for it’s time. In fact, it used two 80186’s — one for the
keyboard/transpose functions, the other for waveform and amplitude
control. One thing led to another and they decided to try to market the
machine after everyone who heard it told them how great it sounded.
They had wanted to call it the “Gleeman Minstrel”, since their family
name Gleeman means “minstrel.” But there was another machine on the
market called Minstrel (the Basyn, by Grey Labs), so they settled on
The oscillator section featured 3 oscillators, each with a selection of
8 waveforms. The waveshapes were fixed, in that there was no
pulse-width modulation. Instead it offered 3 choices of pulse widths.
There were two “digital” waveforms with lots of high, bell-like
overtones which had a distinctive, almost FM-like sound when selected.
There was an octave switch on each oscillator (hi/low) and a “chorus”
switch that actually detuned oscillators 2 and 3. Interval tuning of
the oscillators was not introduced until the programmable version was
made, and the intervals were part of the program, selected by pressing
keys on the keyboard. There was also a Transpose control that shifted
the entire tuning of the machine in half-steps over a one octave range.
It was a standard Prophet-type control set, with one filter ADSR and
one volume ADSR. The filter section had the standard cutoff, contour
amount and resonance dials. The layout was basically that of a
MiniMoog, including an oscillator mixer that included a pink noise
One drawback was a lack of a keyboard tracking filter setting, which
was explained to me as being impossible due to the way the keyboard
controlled the oscillators. Another was that it also lacked a provision
for a sustain pedal.
The keyboard system was unique in that it was not based on the same
serial-scanning system developed by Tom Oberhiem used by virtually
every polyphonic synth, but was rather a parallel port that had an
input point for each of the 37 keys. This made for a very fast,
responsive keyboard, but made it difficult to derive an analog voltage
to use for filter tracking.
The first Pentaphonic’s joystick was only a pitch bend lever, but later
they upgraded it to allow for pitch bending and modulation of either
the pitch or filter cutoff. There was also a simple, real time,
one-track sequencer built in, but with the unique feature of being able
to play back the sequence while playing the keyboard with the joystick
and transpose control effecting only the notes played on the keyboard.
The original Gleeman Pentaphonic retailed for US$2795 and featured a
6X9 inch “car speaker” with amplifier built into the back of the
cabinet. The price included an injection molded road case (actually a
Samsonite suitcase customized with form-fit molding inside to hold the
synth and a “Gleeman” nameplate glued over the “Samsonite” label.)
In 1982, the programmable version was introduced. I had told Bob from
the beginning how much better (and more marketable) the Pentaphonic
would be if it were programmable (as the Prophet-5 was setting the
standard for analog synths in these days.) The “Presetter” used a
two-digit thumbwheel selector next to the joystick with a toggle
switch. The first 50 programs (designed by the Gleemans with help from
myself and Keith Hildebrant, who later worked for Opcode and authored
several sound sample disks) were in ROM memory and the second 50 were
user programmable. The toggle switch allowed for either instant recall
as the thumbwheels were changed, or in the second position the patch
remained in performance memory until the wheels were changed and the
switch was toggled into the “recall” position. A small recessed red
button was the “write” switch. Unfortunately there was no provision for
off-loading of programs. The programmable version retailed for US$3295.
I sold Oscar Petersen his Pentaphonic a few months after we became a
dealer. He was playing a concert in town nearby and came into the store
just to kill time after the soundcheck. He started playing on the
Pentaphonic and didn’t stop for two hours, while a small crowd gather
to listen. He told his road manager he had to have one, and Bob and I
delivered it to him at the venue the next day.
The greatest thing about the Gleeman was the sound — it was gorgeous!
The pads were thick and rich; the string patches made an OBXa sound
almost thin by comparison. The three oscillator sound was very similar
to a MemoryMoog in some ways, but with a crystal clarity that the Moog
couldn’t touch. If it had a weak point, it was that the Gleeman was
almost TOO “pretty” sounding — not a very good “down and dirty” synth.
It was no good at the kind of bizarre patches that the Moog and the
Prophet were capable of. It lacked a sync mode and the limited keyboard
range was a hassle, but within that range, it was a truly lovely
To address these defects, the Gleeman brothers had plans for a 61-note,
touch sensitive, 8-voice version of the synth (I even saw the prototype
being built while visiting their workshop). MIDI was just becoming
available, and the new machine would have MIDI (though by then
programmable Pentaphonics could be retrofitted for MIDI by the shop.)
Unfortunately, by 1984 the Japanese synth builders were flooding the
market with inexpensive polysynths (like the PolySix and the Juno 6/60)
and the market for a 5-voice machine with a 37-note keyboard and a
price tag over 3000 bucks was gone. And soon after that the DX7 was
introduced and the market was radically changed. The Gleeman
“Octophonic” never saw the light of day, and the Gleeman brothers
retired from the synthesizer business. (I heard that years later Al
Gleeman went on to invent the laser dentist’s drill.) Only 50 or so
Pentaphonics were ever made but they still pop up in the keyboard rigs
of some major recording artists such as Kansas, The Band, R.E.M. and of
course, Oscar Petersen.
But the Gleeman didn’t disappear until after it had made a bit of a
stir in the synth world with the introduction of the world’s only
see-through synthesizer — the “Pentaphonic Clear”.
The Pentaphonic Clear
All right, I’ll admit it — the Pentaphonic Clear was my idea. Sort of.
Really. It happened like this:
Keith Hildebrant loved the Pentaphonic but wanted a “portable” keyboard
(like the Prophet Remote)he could strap over the shoulder.
So I got the Gleemans to take Keith’s standard Pentaphonic, remove the
keyboard and build a separate box to hold it with a detachable
multi-pin connector cable. After consulting with me and Keith, they
made the remote case out of a sheet of clear plexiglass, sawed and
glued together into a rectangular box. The gap left in the body of the
original synth was merely covered with a sheet of black plastic. As far
as I know, it was the only one ever made.
But the clear plastic keyboard remote looked very cool! Keith installed
some tiny “tivoli” lights into it for maximum flashiness. When they
delivered the finished machine, and commenting how cool a clear box
looked, I suggested that a totally clear case on a standard Pentaphonic
would be a really snazzy looking machine. (I was inspired by seeing
Ultravox on stage where the drummer had a CR-70 drum machine built into
a clear plexi case with blinking lights in it.) Bob had also seen an ad
put out by Sequential for the Pro-One which they had built a custom
clear plastic case for it (they used it as a novelty item to display at
trade shows.) The Gleemans liked the idea and decided to run with it.
The Clear model was functionally identical to the original black,
except the idea was to make it so that it would be feasible to wear the
thing around one’s neck like an accordion (which it was roughly the
size and shape of anyway.) To this end, the speaker and it’s power amp
was eliminated, and the power supply was removed and placed in a small
separate steel box with a multipin connector cable to carry power to
the machine. The audio output jack was also placed in the outboard box,
so the player only had the single cable trailing behind them to trip
The Clear’s case was made of Lexan plastic instead of Plexiglas, and
was lit from inside by small tivoli lights. The knobs were clear
Plexiglas balls, with set screws in them that served as the pointers. I
was the first person besides Bob and Al to see a Clear, and it was a
real head-turner in my keyboard shop. No other machine ever looked
quite like it, and the Pentaphonic enjoyed a slight revival in sales
before it’s ultimate demise. Many major keyboard artists boast of
having one of those “cool, clear little synthesizers” and they still
pop up in keyboard rigs on stage and video. You can’t miss it.