By Thor Zollinger, writer/musician/engineer at large.  2018

I recently acquired a new piece of hardware, a rare Technics SX-WSA1R virtual acoustic synthesizer from 1995.  I like instruments I can reprogram, they have an unlimited voice potential unlike a lot of modern keyboards.  After previewing all of the factory presets, I decided to dissect the internal workings of the WSA1 using a spectrum analyzer to see how it works.  The idea here is to be able to look at a recording of a sound on the spectrum analyzer, then select a Driver (or multiple Drivers) by ear and mate it to a Resonator knowing what each Resonator does to the sound both aurally and visually on the spectrum analyzer.  I figure if I know more about how it works inside, I should be more effective at programming it.  

Let’s take a closer a look at the internals to the Modeling section of the synthesizer.  In essence, the WSA1 is a combination of a sample based synthesizer and a subtractive synthesizer with a creative twist. 


The sound processing chain begins with selection of a Driver.  There are 307 Drivers to choose from, all named after instruments you’re familiar with.  The Driver is a recorded sample of an instrument, including the note strike and timbre changes all the way through the note sustain.  It shapes the personality of the instrument you are modeling by setting up the harmonic structure of the sound.  There is a slight flaw in some of the Drivers, there is a noticeable cycling in the sustain loops of a couple of the Drivers.  You can mask this by making the patch more complex.

WSA1 Drivers are not the same as samples on other synthesizers.  The sample has been reverse modified to remove the effects of the instrument’s Resonator.  Listening to them raw with no Resonator, they sound higher pitched and scratchy.  They include a lot more of the high frequency components of the sound than you generally hear.  Most of us can select a Driver or a couple of Drivers to mix together based on what we can hear in the sound.  You don’t really need to see it on a spectrum analyzer for the WSA1 like you do on an FM synthesizer.  On an FM synth you have to construct each harmonic in the sound from the ground up, you can’t simply select a sound you know from a list like we can on the WSA1.  


All of the basic modifications to the Driver waveforms are performed by the Resonators.  The Resonator has two parts to it, a comb filter and a set of broader bandpass filters.  The fine-toothed comb filter selects a set of harmonics out of the sample in most of the Resonators, then the broader bandpass filters adjust the volume levels.  (Bear in mind that my explanation may not be exactly correct, my description is based on what I’m seeing on the spectrum analyzer.) 

To see the filters in action I selected the White-Noise Driver and passed it through each of the different Resonators.  I was surprised to hear a solid harmonic tone coming out of the String Resonator since I was using a generic White Noise source with no harmonics.  The comb filter acts like a set of a hundred very narrowly tuned resonant filters, pulling harmonic tones up out of the noise.  It creates harmonic peaks where there were none.  The comb filter is designed to enhance the harmonics in Driver waveforms which do contain harmonics, and selectively remove some of the harmonics.  Resonators with the comb filter include the String, Cylinder, Cone, Flare, and Special-1 Resonators.  The exceptions are the Mute selections, which do not include the comb filter.

STRING:  This Resonator passes and enhances ALL of the harmonics.  This Resonator is obviously for string instruments like the Guitar, Violin, or Piano, with characteristic waves in the harmonics.

CYLINDER:  This one passes just the Odd harmonics, 1,3,5,7,9… This Resonator is for Flute and Clarinet sounds.

CONE:  The Cone Resonator passes ALL of the harmonics at varying amplitudes.  The Oboe is one example.  You see larger arched resonances in this type of instrument.

FLARE:  This Resonator varies ALL of the harmonics similar to the Cone Resonator, but increases the amplitudes of the higher harmonic bands to get a brassier sound.  Brass instruments like the Trumpet have a flared bell.

SPECIAL-1:  Only every 4th harmonic is passed (or created) in this Resonator, 4,8,12,16,20…  This Resonator also has a cycling harmonic sweep built into it.

(There are additional plots further down in this article.)

The Resonators also utilize a set of wider bandpass filters to sculpt the shape of the harmonics.  These wider filters are more like a shaped harmonic equalizer and adjust the volume levels of the harmonics to match the Resonator type.  In the plots above you can see first the noise-only plot, then the Cone plot to see what the Cone Resonator does to the noise.  It creates a prolific set of harmonics, then it alters the shape of the harmonic volume levels in the most audible range, from 10 hz up to 7.0 khz.  These filters are also dynamic.  Play the same note ten times and you get a slightly different filter shape every time.  Hold a note for several seconds and you can watch the filter shape morph slowly.  The WSA1 is designed to give you a custom performance feel from the ground up. 

The remaining Resonators, the Plate, Membrane, and Special-2 Resonators (and all Mute selections) don’t include the comb filter, they just use the set of wider, more general bandpass filters to sculpt the levels of the sound like an equalizer does.  These filters adjust the overall volume levels of the sound across the entire spectrum, mimicking the resonances of different kinds of percussion instruments and reverb modules.  You can also pass non-percussion waveforms through these Resonators, which results in passing all of the harmonics in the original waveform un-altered.  It doesn’t ‘select’ or ‘create’ harmonics like the comb filter does.  The Membrane Resonator is the most interesting of these, shown below.

                PLATE:  This mimics the older steel plate styled resonance chambers from the 60's and 70's.

                MEMBRANE:  Emulates the resonance inside a Drum.

                SPECIAL-2:  This Resonator has a cycling harmonic sweep built into it.

                THROUGH:  This is the ‘No Resonator’ setting, with none of the variable characteristics.

The filters also have another behavior we need to address.  All of the Resonator filters expand and contract in width to follow the note you play on the keyboard.  The comb filters move to follow the movement of the fundamental harmonic (the note you play on the keyboard) and the comb expands and contracts to match the harmonic set that comes with that fundamental.  The more general shaped bandpass filters also expand and contract in width to match the key you press. 

At low volumes, the Resonators also do one more thing (seen in the Membrane plot above).  They amplify the highs and suppress the lows all across the spectrum.  This creates sharp arched shapes in the harmonics, accentuating the characteristics of each Resonator type. 


The real changes you see between the different Resonator types are in levels of the first dozen or so harmonics.  These harmonics give the sound it’s character, the signature sound of each instrument is captured in the volume levels of these harmonics.  Match the first dozen or so harmonics, and you capture the essence of the sound of the instrument.  This works on most instruments, the exceptions being the Piano, Harpsichord, Saxophone, and percussion instruments which require more high frequency components than other instruments. 

In the WSA1 the levels of these harmonics are first set by the Driver, then they are modified by the Resonator.  I’ve zoomed in slightly on this portion of the sound below so you can see what each Resonator does to the sound.  I’ve used the same White Noise Driver as before and played the same C1 note on the keyboard. 

First up is the original Driver White Noise sound with no Resonators at all for comparison.  There are also a number of additional sub-resonator selections in each category below, but I’ve opted to just show you the main categories.  There are plenty of charts below to compare as it is.

If you look at these first few plots very closely you’ll see that the all of the Resonators that use the comb filter emphasize the Seventh harmonic.  Emphasizing the fundamental harmonic is obvious, but the 7th?  That forms a minor seventh chord in the harmonics.  I find that quite interesting.

The next three plots/resonators below don’t use the comb filter and pass the White Noise Driver without much change.  They simply fine-tune the sound to match the resonance of the intended filter.  These include the Plate, Membrane, and Special-2 Resonators, shown below.

The Membrane resonator is up next.  Each Drum Kit only uses one Resonator for all of the sounds in the entire Kit, the Membrane Resonator.  Most of the resonance qualities of the drum voices are contained in the Drivers themselves, not in the resonator.  As a result, the percussion sound Drivers sound pretty much like their named counterparts.  There is so much difference between each percussion instrument this decision on Technic’s part makes a lot of sense.  They used a general purpose resonator, and left all of the specific instrument characteristics in the Drivers. 

Special-1 in the last plot uses the comb filter we’ve discussed before to bring out every fourth harmonic, emphasizing the higher octave notes and Fifths to form a Major chord in the harmonics.  If you look at the plot above more closely, the 18th harmonic also sneaks in at about half amplitude, a ‘D’ to a C-major-chord.  I’m not sure quite what that adds into the mix.  It does continue to follow the notes in the major Ionian mode, though.

            4th          Octave,

8th          Octave,

12th        Fifth,

16th        Octave,

            20th        Major Third,

24th        Fifth


The Connections block in between the Driver and Resonator in the processing chain allows for cross-linking of the Resonators.  Using this feature you can thicken up the sound, removing the thin nature of some of the factory patches.  It also includes several ‘movement’ settings to alter the sound slightly for each note, giving it human-player like variations.  A formant is used to slightly alter the timbre of the sound as each note is played.  These settings are also connected to the input controllers so the player has control over the expression of the instrument.  These include the Aftertouch controller, Mod Wheels, and the Realtime Creator and Realtime Controller trackballs.   These controls add character to each note, spicing things up and making the performance more realistic. 

Coupled with all of the Controller capabilities of the WSA1, you can really create a convincing humanized performance.  I particularly like the way the factory patches are already set up to use Velocity and Aftertouch controllers in every single patch, along with the Realtime Creator on the WSA1R.  Yamaha didn’t follow this path, they didn’t program in any Aftertouch controls (or any other controllers in most cases) on most of the Motif keyboard series patches because too many piano players complained about it.  It’s nice to see Technics wasn’t shy on this count, I like the Aftertouch controller.  This is a synthesizer and not a piano, after all.


The methodology for creating new patches is different on the WSA1 than on a lot of other synthesizers.  You can’t construct a sound by adding in each individual harmonic or groups of harmonics like an analog or FM synthesizer can, you don’t have quite that kind of control with the WSA1.  Patches are constructed by mixing and matching different instrument sounds together within a Sound and mating them to out-of-the-ordinary Resonators.  You can mix up to four Tones in one Sound.  I found by digging through a number of the USER1 patches (the ones that don’t sound like specific acoustic instruments) you can achieve some really nice pads with the WSA1.  In several instances Technics used one of the sound effects Drivers, the guitar slide sound, shifted several octaves down to add an airy resonance.  The Fog Vox Driver was also selected in several patches, as was the Tambourine jingle sound which was also octave shifted. 

You need to scribble outside the lines with the WSA1 to get at the more interesting timbres, make sure you experiment with sound effects and percussion instrument Drivers in ways you wouldn’t ordinarily use them. 

EXAMPLE PATCH – The Yamaha VP1 ResoMetal Patch

As an experiment I decided to try and match one of the Yamaha VP1 patches.  The VP1 is an extremely rare synth, Yamaha only sold three at over $25,000 each.  It was more of an experimental prototype than a production synthesizer.  Sometimes the WSA1 is called a poor-man’s VP1 because of the similarities in the sounds.  I have recordings of a number of VP1 patches, single notes played on different keys up the keyboard.  I started with a recording of a very low C1 ResoMetal patch, which sounds a bit like a plucked bass with a huge amount of resonant overtones.  You can listen to it below, it’s a really lush, gorgeous bass.  The ResoMetal patch transitions into an Asian Gamelan as you go up the keyboard, so I’ll be mixing two or more Tones together to get the right sound together. 

               Note C1 – VP1 ResoMetal                            Note C4 – VP1 ResoMetal                            C1 to C5 Run

I then went through all of the patches on the WSA1 and wrote down a set of ten from ROM1 and ROM2 that sounded close, playing a low C1.  After reviewing them again, I selected a couple that sounded the closest and began constructing the patch. 

Now that I’ve dug around a bit on the WSA1, I’ve also found the programming interface with it’s large screen to be particularly friendly.  It’s not hard to find your way around using the control screen and all of the buttons, and the layout of the software is not difficult to learn.  The number of adjustable parameters is also not overwhelming.  I find it to be just about right.  The only thing missing is the lack of being able to import your own custom Drivers.  If Technics had allowed that feature, the instrument would have been so far ahead of the pack it’s not even funny.  It’s too bad Technics bowed out of the synthesizer market after their first attempt just because of a marketing error.  The WSA1 is truly a remarkable instrument. 


There are two different blocks of Effects on the WSA1, the Digital Effects block and the DSP Effects block. 

Digital Effects are insertion effects, you apply them directly to one of the four Tones that make up a custom Sound in the instrument. 

These include Celeste, Chorus, Ensemble, Tremolo, Organ Tremolo, Single Delay, Repeat Delay, and Solo Effect. 

DSP Effects are broader in application, they apply to all of the instruments currently playing in the Combination or as a Part of a midi instrument setup.  You can select a type of Reverb, an Effect-1, and an Effect-2  for use, and control how much each effect is applied to each Part or instrument. 

Reverb types include Room, Plate, Concert, Dark, Bright, and Wave. 

Effect-1 & 2 includes Chorus, Modulated Chorus, Enhancer, Flanger, Phaser, Ensemble, Gated Reverb, Single Delay, Multi Tap Delay, Manual Delay, Distortion, Overdrive, Fuzz, Exciter, Compressor, Slow Attacker, Noise Generator, Parametric EQ, Auto Pan, Pitch Shifter, Vibrato, Pedal Wah, Auto Wah, Rotary Speaker, Ring Modulator, Haas Effect, Mix Up, and 16 combinations of the Effects listed above. 

I get so involved in editing the voices in synths a lot of time I forget to dig into the Effects section until I absolutely need them to create a particular voice I’m working on.  Don’t forget that Effects units have a lot more capability than most people ever touch, and sometimes they’re the difference between a good voice and a fantastic one. 


Most of this discussion has been pretty academic, sorry about that.  Hopefully some of this is useful to you.  Most of the time on the WSA1 you can simply listen to a recording of the sound you want to create, then select a couple of appropriate Drivers to mix together to achieve a tone similar to it.  You can’t match the timbre exactly, there are no provisions on the WSA1 to edit individual harmonics.  But, since each patch can contain up to four different Driver-Resonator pairs you can mix and match voices together at will.  This is a huge contrast to programming the Yamaha FM synthesizers.  With FM you have to resort to a spectrum analyzer just to get the tone in the ballpark, but you can replicate almost ANY tone with an FM synth.  That’s FM’s strength, and also it’s inherent downfall.  Almost no one knows how to program an FM synth to get a specific tone.  Except for the primer I wrote (available on my website at JavelinArt.com) there aren’t any real manuals on how to program FM.   The WSA1 is much more straight forward.

All in all, Technics has made it quite easy to create new and imaginative acoustic sounds on the WSA1.  And since there are a set of around 56 analog and sound effect Drivers in there as well, it isn’t limited to purely acoustic instrument sounds.  Add to that the Drum Kits, and the WSA1 is truly an all-around capable midi instrument.