Roland SH-7

The flagship of Roland’s SH series synthesizers, the SH-7.

Roland’s SH series are undoubtably some of the finest synthsizers ever made. They stand head and shoulders above most of their competition from that era for reliability and build quality and their sonic character was up there with the best. It’s hard to think of a more reliable and potently useable synth than the little SH-2, a true dark horse of monophonic synthesizers and an instrument that people who own them usually put on their “never sell” list.

The SH-7 was the pinacle of the SH-series, it is also quite rare. It’s closest cousin is the SH-5 which many people prefer over the SH-7 due to the SH-5’s multimode filter, a second LFO and the extra band pass filter. this has led to a belief that the SH-7 is a less desirable instrument but this actually isn’t the case, the SH-7 is a different instrument and it has capabilities that the SH-5 cannot match and vice-versa. The SH-5 and SH-7 each have unique routing features that set them apart from one another. The SH-7’s filter is a basic low pass setup with the classic Roland sound of the period enhanced by a rich choice of modulation sources. It also has two full ADSR envelope generators and separately clocked and routable LFO and sample and hold sections. The SH-7 has flexible oscillators with an additonal additive square wave capability on VCO 1 and comprehensive VCO modulation choices. It’s biggest feature that sets it apart from it’s SH series siblings and almost every other synth is that it has a duophonic keyboard and this makes the SH-7 a truly desirable live performance synthesizer.  Each of the Roland “green series” synths have their own character, each has its own unique traits. The SH-7’s strengths are it’s duo keyboard and it’s instant routing capabilities that have led to it being described as almost modular.

Like the ARP Odyssey the SH-7 shines as a performance synthesizer. It’s duophonic keyboard allows expressive control that a mono-synth cannot approach. The ability to play instant intervals during a lead solo is a potent performance feature and this is taken to a whole other level if the ring modulator is brought into the mix – Bring up the ring-mod slider along with the two VCO’s into the pre-filter mixer and it adds some nice growl when the VCO’s are tuned to the same note and then play a fourth or 5th interval and the sound changes radically with the addition of some classic ring modulator harmonics. Without touching a control a player can change the sound of a clean lead solo instantly into a growl. This is a great synth to take on stage. Bringing up the auto-bend on one VCO is another way to add ring mod grunge to a solo. This is one of the key things that makes the SH-7 so desirable – add an expression pedal and you have a stage synth that in many ways has the flexibility of a modular and the expressiveness of an Odyssey.

It is quite a deceptive synth at first glance – it seems to be a basic synth until you begin to use it and you realise that there are jacks, switches and functions here that don’t appear on many other synths such as autobend, triggers as well as gates for the dual envelope generators, single/multiple multiple triggering capability in single note mode and the ability to fire the envelope generators from an external pulse via a rear panel jack.

The features list is impressive – Autobend with variable time and polarity, oscillator sync, a separate S/H section independent of the LFO, a mixer that can be overdriven into the filter with an LED overdrive indicator, VCO 1 is divided into two sections with the standard “full set”of switchable waveforms complimented by another additive section of square waves mixed in an organ drawbar-like way on a set of 5 sliders. The LFO clock can be used to re-trigger the keyboard and the ring modulator had an external input. Portamento can be switched to 3 different response types, the bend lever has 6 modes, it has a trigger input on the back panel along with the usual gate input. The duophonic keyboard can also be switched to single-note to allow trills to be played, in this mode the keyboard has a high-note priority. The keyboard is made even more powerful by the availability of both gate and triggers on the envelope generators which allow smooth legato or re-triggering on every key strike for a rapid staccato note response depending upon how the switches are set. The trigger input socket on the rear allows external synths and sequencers to fire ether or both envelope generators with pulses.

The SH-7 also has an envelope follower – the level of the external audio input is automatically converted into a control voltage that can control the synth’s filter cutoff. This allows effects like auto-wah or to have the filter brightness follow the volume of the external signal, giving a nice expressive capability when using the external audio input.

Roland’s VCO’s of the period are stable and reliable, all of the SH series are easy to keep in tune. The use of sliders rather than rotary pots on the SH-7 has advantages and some disadvantages – Sliders are more susceptible to dust and they are more difficult to set precisely than rotary controls. If you have ever tried tuning the VCO’s in an ARP you will know what I mean but there are big advantages to using sliders too – They allow for more controls in the same panel area and they are very visual – it’s easy to instantly see where each control is set and it therefore makes changing settings faster and more intuitive than any rotary control based instrument, particularly on stage or in in low light. You can also move multiple sliders at the same time with one hand, even in different directions.  Roland cleverly eliminated the annoying limitations of sliders in critical areas by using rotary pots for the controls that do need fine precision – The VCO tuning controls.

The SH-7’s construction is typical of the period for a Japanese synth – quality plywood case covered with black Tolex, a steel top panel painted in the company colours of the period, a solid key action with metal leaf contacts that is reliable and resistant to tarnishing problems, solid, high quality switches, pots, sliders and jack sockets. The keyboard can become a little noisy and clunky as the felt bushings get compressed over time, resulting in a clank sound as the key comes back up and hits the front rail however it’s a simple matter to remove the old felt strip and replace it with a new one. These key actions are far more robust and reliable that the Pratt-Read actions with J-wire contacts and the Panasonic silicon bubble contacts used in many later synths. The SH-7’s power supply is a simple, robust +/- 15V linear supply that unusually has additional +/- 10V outputs for the keyboard control voltage circuits.

The SH-7 is old enough that some IC’s are early round metal can types, for example the CA3080 transconductance op-amp pictured above. Other IC’s are the newer black plastic inline type such as the ubiquitous 4558 IC, also pictured. Both of these chips are extremely common in vintage synths, the 4558 is available to this day, the CA3080 is discontinued but not too difficult to find in the inline case. The period when the SH-7 was produced was a time when IC’s were still fairly new and undergoing a lot or change and revisions. It can make servicing challenging at times, the old metal can style CA3080’s are difficult to find and substituting the later version in the modern rectangular plastic case presents the problem of how to plug a chip with two straight rows of pins into a place that was occupied by a chip with pins arranged in a circle. Both versions are electrically identical but physically different. Either will work perfectly.

The image above shows the full internal layout of the SH-7. They are easy to service due to the excellent accessibility of the boards containing the main circuitry. The board on the bottom left in the bottom of the synth is called the CVH-1 board and it contains the keyboard CV and gate circuits, the sample and hold circuit that remembers the last note that was played after the key is released during the envelope release stage (not to be confused wth the S/H function on the synth’s top panel). It also has the portamento and key re-trigger circuits and the headphone driver amplifier. The little board to it’s right is the CVH-2 board which only appears in earlier SH-7’s, later machines had this circuitry integrated onto the CVH-1 board itself.

The board on the top left side of the picture is the LFOH-1 board containing the LFO and the sample/hold circuitry.

The board second from the left of the picture is the VCOH-1 board, it contains the circuitry for VCO 1 and the divider system for the the 5 square wave generators. The autobend circuit is also on this board.

The board second from the right of the picture is the VCOH-2 board, it contains the circuits for VCO 2.

The board on the top right side of the picture is the OPH-14 board, it contains the VCF and the VCA circuits along with the two envelope generators, the envelope follower, the ring modulator, the audio mixer and the external signal input amplifier, the high-pass filter and the noise generator. The VCF is a four stage 24dB/ocatve lowpass OTA design. 

The board on the bottom RHS behind the keyboard  is the PSH-13/14  power supply board. 

The remaining boards are the two top panel boards with all of the pots and switches mounted on them, they are the green boards at the top behind the main synth boards. Beneath the LHS pitch bender panel is the OPH-35 board that holds the bender, portamento, octave and volume controls.

Looking at the two images above you can see just how old school the electronics are in synths of this vintage. The circuit boards are simple and single sided, one layer of copper tracks, large components with plenty of space between them, the large capacitor with a leg soldered to those of an IC and a transistor in mid-air presumably to avoid leakage of the keyboard CV memory due to dirt or dust on the board. There is even a transformer to drive the headphone output. Clearly this board was assembled by hand and it’s simplicity makes it very easy to trace and repair faults. Compare this to modern multi-layer boards covered in a sea of nearly microscopic surface mount parts. Many issues with the SH-5 and SH-7 simply stem from dirty connectors, there are many of them inside each of these synths.

The two pictures above show a couple of parts that most people never think about – A power supply transistor mounted on an aluminium plate (a heat sink) to keep it cool, and a fuse. All of the power for the synth goes through that tiny piece of wire who’s job is to self-destruct if something fails inside the synth and starts pulling too much current. Without this tiny part a simple fault in a $2.00 chip or capacitor somewhere inside the synth could damage the machine by killing other expensive parts. If you ever have a fuse blow in your synth always replace it with exactly the same rated fuse. If it blows again never be tempted to put a larger fuse in there in it’s place because what will happen then is that instead of the fuse blowing the transformer will blow and you will have an expensive repair bill to replace it. And possibly smoke. Or worse.

Another oddity of the SH-7 stems from the nature of VCO 1 (A) – The set of square waves that can be mixed much like the drawbars of an organ. Because of this the synth actually has some technology inside that you wouldn’t normally see in a mono/duo synthesiser, the SH-7 has some parts that are normally found in organs or string machines. The reason for this is that the output of VCO-1 has to be divided and multiplied in order to create the 5 separate octaves for VCO-1 (A). Staying on the subject of unusual chip packages the odd little device pictured above is actually an obscure IC, it’s a low power flip flop IC called a DN819 and it’s part of the divider circuit for VCO 1. It feeds into another obscure organ chip, an LM3216 which is a 6 stage divider IC. Another unusual feature of VCO 1 is that instead of the traditional sawtooth output this VCO has a narrow pulse output with a sloping rather than flat top. It is designed to drive the divider circuit and it is also fed into wave shaper circuits to create the triangle, sawtooth and pulse waves that can be selected from the front panel.

Roland stands as a giant among synthesizer manufacturers and the SH-7 is a testament to the ingenuity, attention to detail, materials selection and superb industrial design that was a company hallmark right from the beginning. The SH-series synths are incredibly reliable, the electronics are stable and robust, the cases and materials are strong and the designers clearly understood things from a musicians perspective. Most issues with these machines come from lack of use or from neglect – sliders, switches and jacks that can become intermittent or gummed up from improper storage or dust or dampness. The circuit design and tolerances are such that parts rarely fail from stress and most parts are still quite readily available – Some parts are tricky but they can still be found with some perseverence on the internet. If you are lucky to find one of these rather rare machines for sale the usual guidelines apply – A synth that is in good cosmetic condition has probably been looked after reasonably well and that is the desirable choice. If it has been in storage for years expect to have to take it in for service to get the switches, jacks, contacts and sliders cleaned and lubricated. They are not a synth that seems to suffer from worn or leaking electrolytic capacitors, they are easy to calibrate and the SH-series are generally a safe bet as a choice for those are looking for a vintage synth to purchase. Periodic VCO scaling is easily performed by the user without the need for a trip to the service centre via holes in the rear of the synth near the jack sockets, a tuner and a small screw driver is all you need.

It’s hard to describe just how rewarding it is to play the SH-7. It’s duophonic keyboard gives it the ability to instantly add a guitar like grunge to your playing simply by hitting that second note. You can sweep your eyes across the synth from one end to the other and immediately you get a feel for where all of the controls are set and this gives a player a feeling of control over the instrument that just doesn’t happen on a machine that is a sea of knobs. The SH-7 is visual and engaging and invites you to dig in and play it with confidence and to move those sliders. It feels solid, heavy and substantial. It feels like a true classic. Take a look at the opening of the INXS video “Don’t Change” to see the SH-7 in action.