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Kenton Plugstation Modular Hosting System For Yamaha PLG Synthesis Cards By Martin Walker
Published August 2001


Yamaha's PLG‑series synth expansion cards have proved hugely popular among owners of their synths and soundcards, but a new product from Kenton allows up to four of them to be used independently — and with improved sound quality. Martin Walker checks out the Plugstation.

You might be tempted to think that the sales of hardware synths would be plummeting now that so many soft synths are available. However, this hasn't proved to be the case, partly because some models still have an indefinable 'something' that hasn't yet been translated into algorithmic form, but mainly because today's computer processing power is still insufficient to recreate most modern hardware synths in their entirety. It's hardly surprising that hardware synth manufacturers aren't falling over themselves to make their expertise available in software form, either. Roland have released several versions of their Sound Canvas technology in virtual form, including a licensed version for the DirectMusic component of Microsoft's DirectX 6.1, but they are no match for the company's latest USB and MIDI Sound Canvas modules.

The other main synth manufacturers have drawn on their existing expertise to develop hardware that can be fitted into a computer, rather than software. Korg dipped their toes into computer‑based waters with the extremely impressive but rather expensive OASYS PCI card. However, it's arguably Yamaha who most wholeheartedly embraced the world of computers with the SW1000XG, essentially an MU100R synth on a PCI card with additional audio recording/playback facilities. One of the reasons for the success of the SW1000XG was the inclusion of a single PLG daughterboard socket exactly like those built in to Yamaha hardware synths such as the CS6X/R, S80, MU100/128, and the new Motif. Unlike expansion cards from most other manufacturers, Yamaha's synth expansion boards don't contain ROM sample data. Instead each card houses a powerful and self‑contained hardware synth, providing a guaranteed number of voices — and unlike software synths, zero‑latency response with no possibility of clicks, pops, or glitches.

There are now six PLG boards available that attach to this 15‑pin socket (see box), including the physical modelling of the VL70m for just £119, a low‑noise modern recreation of the famous DX7 for £199, and an emulated Prophet 5 based on the AN1x design, again for £199. The only way musicians could lose was by running out of PLG sockets — which is where the Kenton Plugstation comes in...

Enter The Plugstation

Installing a PLG card in the Plugstation involves hooking it up to a cable and sliding it along either the upper or lower rail.Installing a PLG card in the Plugstation involves hooking it up to a cable and sliding it along either the upper or lower rail.

Kenton are already well known to musicians for products such as the Control Freak, and their comprehensive MIDI retrofit service for analogue synths. Spotting the potential for a low‑cost PLG expansion device, they came up with the idea of the Plugstation — essentially a breakout box that can contain up to four PLG cards. With the support and backing of Yamaha UK, this simple idea grew during development into a far more versatile product, as we shall see.

The Plugstation itself is a 1U rackmount unit with an attractive if somewhat utilitarian grey and sky‑blue paint job. The front panel is very straightforward, with a power on/off switch, a four‑digit seven‑segment display panel, and a rotary encoder control knob for data entry that doubles as a push button to switch between menu options. The contents of the back panel vary depending on which options you have fitted, but the basic Plugstation has a socket for the supplied universal power supply for worldwide use, MIDI In, Out, and Thru sockets, and a 44‑way D‑Type connector labelled 'SW1000 Interconnect'.

In the centre is a removable panel, behind which is a cavity large enough to house up to four PLG cards simultaneously, with the aid of two sets of guide rails and four flying cables, each terminated in a PLG connector. To these you can attach almost any combination of PLG cards. The only restrictions are that only one XG card is currently catered for, and only one Vcard (which, if present, should be card number four unless it's the only card installed). Yamaha were obviously keen for me to try out the Plugstation 'fully loaded', and sent AN, DX, and PF cards to supplement my own VL daughterboard.

Once all your cards are attached to the cables, you slide one pair of them onto the lower guide rails one after the other, and the other pair onto the upper ones. It's a bit of a fiddle to get all the cables neatly folded in behind each card to make way for the next, but it's not something that needs to be done very often. The blanking panel can now be replaced, and the Plugstation powered up for the first time. During the initialisation procedure the four card slots are each scanned in turn, and any card found will return its signature so that Plugstation knows which model it is. This procedure also confirms that the cards have been connected correctly.

The SW1000XG System

The XGPad editor is being upgraded to include Plugstation support: this is a prototype version in action.The XGPad editor is being upgraded to include Plugstation support: this is a prototype version in action.

Kenton's Plugstation has been designed as a modular system, and there are currently three optional boards available that each add extra features without tying up any of the PLG card slots. The various possibilities can initially be quite confusing, so Kenton have sensibly decided to offer the Plugstation in four versions, each with a different board or combination of boards.

If you already have one of Yamaha's excellent SW1000XG soundcards in your Mac or PC, the cheapest option is the Plugstation SW1000XG system. This includes the X Board, which is a PLG‑format card that attaches to the SW1000XG's PLG socket. The X Board houses a short ribbon cable extending to a new backplate housing a 44‑way D‑Type connector, which attaches via the supplied 1.2‑metre long umbilical cable to the SW1000 Interconnect socket on the back of the Plugstation. With this link cable in place, and your computer powered up, the Plugstation acts like a single deluxe PLG card containing up to four Yamaha synths. You need to switch on the Plugstation shortly after the computer in order that the SW1000XG can recognise the X Board before it finishes initialising and the Plugstation correctly detects the SW1000XG's word clock signal, so that both remain locked together in perfect sync.

The SW1000XG now receives a stereo submix from the PLG cards installed in the Plugstation, each of which has its own level and pan controls adjusted from the Plugstation's front panel (see Front Panel Operation box), while the latter's Global menu also provides an overall level control. Apart from the PLG100XG, which is 16‑channel multitimbral, all the PLG cards are monotimbral, and each can be allocated its own unique MIDI channel. Program and bank settings can also be changed from the front panel, along with MIDI controller settings for basic editing of various parameters.

Many SW1000XG owners have been wanting to access multiple PLG cards like this for ages, and I found it wonderfully liberating to have access to four types of synthesis simultaneously alongside the other sounds of my SW1000XG. You can use the SW1000XG's own effect busses to add reverb, chorus, and insertion effects to the entire submix, but sadly Yamaha's PLG specification doesn't allow this to be done for each card individually. Mind you, the PLG150PF card already has its own built‑in reverb and chorus, so this won't need separate treatment.

I did find it a little tedious to choose presets from the Plugstation front panel, since Yamaha maps them according to the GM list, but with variations scattered across of host of banks. For instance, the PLG150PF places all its 136 piano sounds on program numbers 1 to 8, but spread across 43 banks. However, the wide range of Mac and PC utilities available, such as AN1xEdit, XGedit95, XG Wizard, and XG Works, will allow users to select voices and edit patches in a far more transparent and painless manner. A recent arrival is XGPad, which looks good, and is currently being upgraded to include specific Plugstation support. It should be available by the time you read this, and I'll be looking at it shortly in PC Notes.

Stand‑alone Operation

The Y Board gives the Plugstation separate stereo analogue outputs for each of the four plug‑in cards hosted, as well as eight channels of optical digital I/O.The Y Board gives the Plugstation separate stereo analogue outputs for each of the four plug‑in cards hosted, as well as eight channels of optical digital I/O.

The next stage up the ladder is the Plugstation Stand‑alone system, which includes the Y Board. This is installed inside the Plugstation (normally by Kenton, although you can buy it as an upgrade later on and install it yourself), and adds eight user‑configurable analogue outputs on quarter‑inch unbalanced jack sockets, along with one ADAT optical output. In this configuration the Plugstation generates its own fixed 44.1kHz internal word clock, and is essentially a stand‑alone modular synth. Each installed PLG card becomes a self‑contained synthesizer in its own right with a single stereo digital output, and you can start playing them as soon as you connect a controller keyboard or MIDI sequencer to Plugstation's back‑panel MIDI Input socket.

The internal audio paths in Yamaha's PLG cards are all 24‑bit, and for the analogue outputs Kenton have used 24‑bit Alesis 1201 D‑A converters, which give the Plugstation an excellent dynamic range of 107dB — this probably exceeds the performance of any other PLG host. The ADAT output supplies eight simultaneous channels of 24‑bit/44.1kHz digital audio, so you can use this to send the individual stereo outputs of all four cards en masse to any other ADAT‑compatible device such as an ADAT, a different D‑A converter, or a digital mixer such as Yamaha's own O1V, O2R, or O3D. All this in full digital splendour with a signal‑to‑noise ratio exceeding 112dB!

I was extremely impressed with the analogue audio quality of the Y Board, and had never heard cleaner sounds emerging from a PLG card before — there was simply no discernable background noise at all! You can route each card to any of the four stereo outputs, and it's also possible to send several to the same one to layer sounds if required, although I suspect most musicians will take advantage of the four individual stereo outputs to add separate external effects to each synth.

Fully Plugged Up

Inside the Plugstation: the PLG synth cards inhabit the middle section, while the X, Y and Z Boards fill the rest of the chassis.Inside the Plugstation: the PLG synth cards inhabit the middle section, while the X, Y and Z Boards fill the rest of the chassis.

A Combined system is available including both X and Y boards, so that you can send one or more of your PLG card outputs to the SW1000XG submix return to add global effects, and the remainder to the dedicated outputs of the Plugstation. After a little lateral thinking I also came up with a way to add individual Effect Send controls to each Plugstation card with this system. If you add an SW1000XG Insertion effect such as a reverb to the submix return, and then turn its Dry/Wet mix control to fully wet, you can use the Plugstation outputs to set dry levels, and the individual submix return levels to set up different effect levels for each PLG card from the SW1000XG output.

For just £45 more than the Combined system, the Complete system includes the Z Board, which is well worth the small extra expense, since it allows the 24‑bit internal audio signals of the SW1000XG to be digitally routed back to the Plugstation and out of the Y Board outputs. Like the Y Board, the Z Board is fitted inside the Plugstation (but still leaves all four PLG slots available), and both incorporate a Motorola 56364 DSP chip, as does the Plugstation base unit. It also requires another short ribbon cable to be connected inside your computer between the SI (Serial Interconnect) socket on your SW1000XG and the X Board.

This serial‑port connection is designed to pipe up to eight discrete channels of digital audio from the SW1000XG to a DSP Factory card. A Serial Thru connector on the X Board lets DSP Factory owners maintain this link, but with the addition of the Z Board you can now route the main stereo buss of the SW1000XG, and your choice of up to six other individual MIDI or audio channels from the SW1000XG, to any of the Plugstation's eight outputs. This means that you can play back both SW1000XG MIDI voices and WAV audio through the 24‑bit converters of the Plugstation, for a significantly quieter and cleaner output signal than when using the SW1000XG's 18‑bit NEC D‑A converter. This also avoids the need for the 'smiley curve' output EQ compensation that I mentioned in SOS November 2000 — I tested the Plugstation's outputs, and they are ruler‑flat within their designated bandwidth.

If you want to allocate some of the Plugstation's eight outputs to SW1000XG channels, but have the full complement of four internal PLG cards fitted, you can either route these to the SW1000XG submix return and add global effects to them, or send the outputs from multiple cards to the same Plugstation output to create another submix. You can also use my Aux Send trick mentioned earlier, this time with the advantage that both wet and dry signals can be routed to the 24‑bit Alesis D‑A converters for a squeaky‑clean sound.

One setup that worked well for me was using Plugstation outputs 1‑2 for a super‑clean main SW1000XG mix, 3‑4 for the PLG150PF piano board with built‑in effects, 5‑6 for the PLG150AN to add external effects, 7‑8 for the PLG100DX, again with external effects, and then routing the PLG100VL to the SW1000XG submix return for individual effect treatment, so that its signal got added to the main SW1000XG mix. The Complete system provides very flexible routing, and you can create up to 64 performance memories to save setups.

Final Thoughts

Unsurprisingly, there's been a lot of interest in the Plugstation ever since it was first mentioned as a possibility a couple of years back. However, Kenton have turned the original concept of a 'PLG card expander' into something far more powerful. While the SW1000XG system certainly provides SW1000XG owners with a home for up to four PLG cards, the Stand‑alone version can be used by any MIDI musician, and also provides each card with its own 24‑bit stereo analogue output for cleaner PLG sounds than have ever been heard before, and an ADAT output for direct connection to digital gear. It's also good value — you could easily pay several hundred pounds just for eight digital‑to‑analogue converters in a rackmount case!

The Combined system is certainly more versatile for the SW1000XG owner, but I suspect most of those who would be interested in this will pay just a little bit more and go for the Complete system. This provides the ultimate SW1000XG expansion option, since all your SW1000XG sounds can now emerge for the first time in full 24‑bit glory alongside those of the four PLG synths.

Kenton have made an excellent job of the Plugstation, but the dearth of front‑panel knobs means that it is significantly easier to use if you have some means of controlling it remotely, either from the computer or from a hardware controller box. XGPad will probably be Plugstation‑aware by the time you read this, and as you might expect, Kenton's own Control Freak has already got new presets to control various aspects of the Plugstation.

The various Plugstations are already good value for money considering what's on offer, and for the ultimate bundle, Kenton have put their heads together with Yamaha to offer a 'fully stuffed' Plugstation containing the AN, DX, PF, and VL PLG cards for just £995 inclusive of VAT. This is a serious bargain, since bought separately the bundle would typically cost around £1200. So, if you want a Prophet 5, DX7, 64‑voice PF200 digital piano, and VL70m physical modelling synth, all for under a grand, and each with pristine 24‑bit outputs, you now know what to buy. And unlike any soft synth this comes with guaranteed 86‑note polyphony, zero latency, no drain on your computer resources, and absolutely no clicks or pops!

Front‑panel Operation

Kenton originally intended the Plugstation to be faceless and controlled solely from a computer‑based editor. This will still be by far the easiest option, but those intending to use the Plugstation in stand‑alone mode will need to tackle setup and editing from the front panel alone, using its rotary encoder and four‑digit display, unless they invest in a hardware fader or knob controller.

There are four levels of editing, the current one being indicated by the position of a dot across the top of the display, and you can switch between these using the data entry button. The topmost level is MIDI mode, which displays which cards are installed and active, and whether or not they are each receiving any MIDI data. It's handy to leave the Plugstation at this level during use, since you get continuous visual feedback that your keyboard or sequencer is sending information to the correct card.

Pressing the Data Entry button once takes you to the deeper Card level, where you use the rotary encoder to scroll through the four slots to see which card is connected to each one. When you've selected the desired card, clicking once again on the data entry button takes you to the even deeper Parameter level, where you use the rotary encoder to scroll through the various options. When you reach the desired parameter you just press the data entry button once more to enter the lowest level, Value, where you can use the rotary encoder to alter the setting.

Editable parameters include MIDI channel, program change, and bank selection, level and pan for each card in the stereo submix return to the SW1000XG if you have an X Board fitted, and level and pan for the Y Board outputs. You can also route each card to any of the four stereo output pairs. These settings default to the obvious ones of 1‑2 for Card 1, 3‑4 for Card 2, 5‑6 for Card 3, and 7‑8 for Card 4, but you can also send multiple cards to the same output if desired, and with the Z Board fitted you can also route the main SW1000XG stereo output to any one of the four as well.

If you have multiple instances of the same card, you can allocate each one a different ID number to send it individual SysEx parameter data. The final two card parameters are used to set MIDI controller numbers and their values to alter specific parameters such as filter cutoff (the default), resonance, or attack time without the need for computer software. Other Card‑level options let you alter the eight master Y Board output levels, the master submix return level to the SW1000XG, and set the global device number if you have multiple Plugstations.

Given the obvious restrictions of the seven‑segment display, it's still possible to choose preset sounds and set up routing fairly easily, and even perform some basic sound editing using MIDI controller data. However, there's no denying that the majority of users will find using a computer‑based editor far easier. You don't need an SW1000XG to do this — all Plugstation systems can be edited from a Mac or PC via their rear‑panel MIDI input.

Brief Specification

  • Clock: internal 44.1kHz for stand‑alone operation, or external sync to 44.1kHz SW1000XG clocks.
  • Expansion: four PLG‑specification interface connectors.
  • MIDI: In, Out, Thru.

Y Board Analogue/Digital Outputs

  • Analogue outs: eight, on unbalanced quarter‑inch jacks.
  • D‑A converters: Alesis AL1201, 24‑bit, 128x oversampling.
  • Dynamic range: 107dB (A‑weghted).
  • THD: less than 0.003 percent.
  • Digital out: 24‑bit, 8‑channel ADAT‑format optical.

Global Options

Sixty‑four Performance Memories are provided for your own setups. They store every current Plugstation setting, and you can load and store them, dump them as System Exclusive data to an external MIDI device for safe keeping, and select them from the front panel or optionally from either the SW1000XG or back‑panel MIDI input using program change messages on your choice of master MIDI channel.

I received one of the first batch of official production line Plugstations, and the operating system was finalised just before I finished my review. However, Kenton may still add other features in the future, since the OS is flash‑upgradable via MIDI. With this in mind, a Master Setup mode can be entered by holding down the Data Entry knob when powering up, and from here you can reset the Plugstation to its default settings, check the current OS version, load a new operating system, or analyse the MIDI data being sent to the unit. Users will be able to download free updates to the operating system as SysEx files from the Kenton web site. I was sent one update during the review, and it only took a minute or two to successfully install it.

Yamaha PLG Cards: The Full Deck

There are currently six PLG cards available worldwide (although a seventh PLG100SG 'formant singing' card is also available in Japan), and you can run almost any combination in the Plugstation, including multiple instances of the same card to increase polyphony by enabling Overflow mode. For instance, you could install two PLG150PF boards for 128‑note piano polyphony, and a couple of PLG150AN boards to get a 10‑note polyphonic Prophet 5. The only restriction (as with all PLG host devices) is that only one instance of the PLG100VHarmony board is allowed, and you can't use this card in stand‑alone mode either, since it needs an analogue input provided by the SW1000XG system. The street prices are normally about £30 cheaper than the retail ones I quote below.

  • PLG150AN (£199) features analogue physical modelling to recreate a classic 2VCO, VCF, VCA synth, along with extensive options including sync and cross‑modulation. It also has loads of other extras including a host of waveform and filter types, four‑layer Free EG controller, built‑in sequencer/arpeggiator, and 3‑band parametric EQ and amp simulator effects. Based on Yamaha's AN1x technology, but revoiced to sound like the classic Sequential Prophet 5, it's monotimbral, but the 5‑note polyphony of its Single Mode can be switched to Unison mode for fat 10‑oscillator monophonic voices.
  • PLG100DX (£199) is essentially a DX7 synth featuring six‑operator FM synthesis, but with more friendly computer‑based editing, and no background hiss! It has 16‑note polyphony, 912 preset voices, and 64 user ones.
  • PLG150PF (£229) contains 136 AWM2 piano sounds including acoustic pianos, harpsichord, Fender Rhodes, Wurlitzer, and clavinet, along with some layered with strings and choir. It also features 16 effects including reverb and chorus. Like most of the other boards here this is monotimbral, but its 64‑voice polyphony should prevent the note‑robbing problems that can plague piano parts. With 16Mb of ROM it provides far more realism and expression than the patches found in most GM, GS, or XG sound sets.
  • PLG100V(£99) provides two extra voices of Vocal Harmony using the same technology as IVL's Digitech Vocalist series, to give 3‑part harmony with optional gender conversion and humanisation features. A bit of an oddball this, in a synth context, but handy in conjunction with the SW1000XG's analogue input for vocals and Brian May‑style multitrack guitar sounds.
  • PLG100VL (£119) contains the single‑voice tone generation system of a VL70m physical modelling synth, and although there is no breath control input it's still able to respond to breath control data. This is still one of the most expressive physical modelling synth designs around if you're prepared to provide it with suitable controller data.
  • PLG100XG includes a full XG sound set with 480 preset voices and 12 drum kits, and also incorporates its own Reverb, Chorus, and Variation effects. It's also the only card here that provides more than one Part simultaneously, with 64 extra voices available across 16 extra MIDI channels. It probably won't interest MU100/128 or SW1000XG owners, but will those using the Plugstation as a stand‑alone expander.


  • Plugstation SW1000XG system (includes X Board) £250.
  • Plugstation Stand‑alone system (includes Y Board) £350.
  • Plugstation Combined system (includes X and Y Boards) £380.
  • Plugstation Complete system (includes X, Y and Z Boards) £425.
  • Plugstation Ultimate Bundle (Complete system plus PLG150AN, PLG100DX, PLG150PF and PLG100VL boards) £995.
  • Separate X Board £30.
  • Separate Y Board £150.
  • Separate Z Board £65.

All prices include VAT.


  • The only way to run up to four PLG cards simultaneously.
  • Y Board provides excellent audio quality.
  • Z Board adds excellent output audio quality to the SW1000XG itself.
  • Flexible routing options.
  • Stand‑alone version doesn't need a computer at all.
  • Good value for money.


  • Confusing to operate from front panel.
  • SW1000XG system can only apply global effects to Plugstation cards.


The Plugstation is an extremely clever design that makes the most of Yamaha's PLG technology and provides superb audio quality (even for SW1000XG sounds) at a reasonable price. However, many musicians will want to wait until computer editing is available before they reach for their wallets.