Waldorf STVC

String Synthesizer & Vocoder
By Gordon Reid

The STVC is much more than just a string synth.

There are some who seem to think that playing a string synth will turn them into spotty, friendless nerds doomed to a life of nothing but endless porn and early Genesis albums. This is bollocks, although many still believe that string synths are the preserve of sexagenarians nursing a half of Old Peculiar while repeating stories of how great Reading Festival was back in 1976. However, the popularity of string ensembles has soared in recent years, and the first dedicated hardware string synth of the 21st century was introduced in 2014 when Waldorf took the plunge with the Streichfett module. Now they're at it again, releasing an instrument that some may see as a keyboard version of the Streichfett with a vocoder bolted on for good measure. But, as we shall see, it turns out to be considerably more than that.

The Technology

Although it weighs just 7.5kg, the STVC's thick steel case is quite hefty, and the lips on either side are ideal for live use, making it easy to lift it in and out of cases and on to stands. Similarly, the full-sized, four-octave, velocity and pressure sensitive keyboard feels solid and has a surprisingly firm feel. The feeling of sturdiness is let down a little by slightly wobbly knobs, and even the change from plastic to stainless steel can't hide this, but the only disappointment for me was the position of the pitch-bend and modulation wheels. You'll find these behind the keyboard rather than to its left and, while I understand the desire to save a few centimetres, I wish that manufacturers would stop doing this. The final performance control is an octave selector with a ±2 octave range.

As on some other recent instruments, the STVC's 128 x 64 pixel screen is tiny, but it's just about sufficient if you're prepared to squint. Having done so, you may notice a horizontal line at the bottom of the display. This represents the saved value of any parameter you adjust and allows you to see whether the current knob position is above or below this. That's a nice touch.

The other feature on the top panel is the XLR socket for the supplied gooseneck microphone. As always, the neck of the microphone is too short so a separate mic mounted on a conventional stand is the way to go. Bear in mind, however, that the STVC provides only 2.4V phantom power; you won't be able to use a +48V phantom-powered mic unless it has a separate power supply.

Strings & Solo

The STVC's fully polyphonic Strings section appears to be identical with that of the Streichfett, and an A/B test — even checking for the unevenness in the loudness that I had discovered when reviewing the earlier module — didn't allow me to slip a 1976 Rizla between them. Consequently, the STVC's character remains closer to that of an Eminent 310U or a Solina than other string synths of the era.

The large Registration knob determines the underlying waveform, interpolating between a handful of additively generated waves ranging from the aforementioned strings to various formant-y vocal sounds and a small range of pipe organs. The resulting wave can then be heard at one of three octave settings — 8', 4' or the sum of both — and each note is shaped by its own ASR contour generator. The sound is then directed to the chorus/ensemble that generates the classic string and choral effects. As before, there are three settings for this: Chorus provides a slow modulation using a single LFO, String generates a more complex modulation using two LFOs running at different frequencies, and the combination of both generates the rich ensemble effect that's underpinned every string synth from the Solina onward.

The second sound generator is again called Solo and offers the same polyphonic Bass, E-piano, Clavi, Synth and Pluto waves (here called Tones) and, as before, you can morph smoothly between these. Happily, the polyphony has now been increased from eight voices to 16, and this proves to be a significant improvement. In addition, there are two extra monosynth Tones called Mono and Full. A switch selects between this section's AD and ASR contours, with an Attack that adds a loud (and intended) percussive thunk between the 7 o'clock and 10 o'clock positions, and a Decay/Release with a maximum duration of around 20 seconds. The fourth knob here is called Tremolo. When the STVC is outputting a single channel of audio or when the Solo section is being used as the carrier for the vocoder, this is the effect generated. But when the output is stereo, the Tremolo is replaced by auto-panning. In either mode, the knob introduces the effect as you move it away from zero and then increases its rate as you rotate it toward its maximum.

As before, you can play the Solo section above or below a user-defined split point but, because it's always layered with the Strings, you have to jump through MIDI hoops to obtain the sounds of the two sections separately. Apparently, this limitation was discussed when the STVC was conceived but, for reasons that I can't imagine, the designer insisted on retaining the Streichfett's architecture. This was a mistake. The enhanced Solo section — and, in particular, its new monophonic sounds — deserves to be played and heard independently.

The Vocoder

Despite the improvements already discussed, the most obvious difference between the STVC and the Streichfett is the addition of its 256-band vocoder. Used in its simplest way, you stick the supplied microphone into its socket, turn the Balance knob to Strings, switch the vocoder on, choose whether you want the output 'clean' or thickened by the chorus/ensemble effect, press some notes on the keyboard and then sing or speak into the mic. But there's a lot more to it than that.

Firstly, you can obtain a huge range of carrier waves. If you use the Strings section as the carrier, there are five waveform types, called F (which lowers the formants to obtain deeper voices and effects), N (neutral, something approximating a simple square wave), J (which adds jitter to create noisy, speech-like effects) and F+ (which shifts the formants upward to create child-like voices and chipmunks), and you can morph smoothly between these to fine-tune the underlying timbre. Secondly, you can use the Solo section as an additional carrier by selecting its Layer option and adjusting the Strings/Solo balance to determine the relative contributions of the two sections. But, as they say on all the best shopping channels, there's more...

On the rear panel (see 'The Rear Panel' box) you'll find a quarter-inch socket that can act as a monophonic audio input, and you can determine whether the audio presented to this is used as the vocoder's modulator or as its carrier. This opens up all manner of possibilities including (if you jump through a few hoops) the ability to vocode a signal with itself. But there's still more...

The modulation matrix (which we'll address shortly) also provides six parameters that can be programmed and modulated to further modify the vocoder's response. These include a formant shifter, the ability to modulate the jitter when using the Strings section as the carrier, the ability to alter the rate at which the coefficients are generated when analysing the modulator signal, and the ability to add 'leakage' of the modulation signal into the output. (Instant Jon Anderson!) These make the vocoder far more flexible than it would otherwise be.

The final trick up the vocoder's sleeve is called Freeze. This appears to allow you to record a few seconds of the audio received at the modulator input although what it actually does is save the filter coefficients generated from that signal. Once recorded, you can trim the duration using the Freeze Start and Freeze End parameters, and the resulting signal then loops when you play the keys with the vocoder selected. Interestingly, you can modify the starting position and playback speed using the modulation matrix, which offers yet more possibilities. Unfortunately, you can only save a single Freeze within the STVC itself, which is a huge limitation. Sure, you can dump and recall a Freeze, but think how much better 128 Freeze memories would be. Furthermore, the Freeze loop is replayed monophonically, which means that all the vocoded notes are at the same point in the loop, no matter how many keys you press or when.

Effects & Modulation Matrix

Like the Streichfett, the STVC offers three effects in addition to the Strings' chorus/ensemble and the Solo's vibrato. Animate modulates the Strings' Registration and you can use this to create the equivalent of pulse width modulation, a range of 'ya-ya-ya' effects and some unusual rhythmic effects. There's no way to synchronise these to MIDI clock, but you can at least control the modulation rate using a MIDI CC. Next comes a gentle phaser that also acts upon the Strings alone. Finally, there's a simple reverb that affects the outputs from both the Strings and Solo sections. You can only program one of these effects at a time from the panel but, if you're prepared to dive a bit deeper, all six of the LFOs that drive them are available as sources in the modulation matrix and all of their rate/depth and size/mix parameters are available as destinations. This is good stuff.

The five-slot matrix is perhaps the most unexpected addition to the STVC, not least because you can use it to program absolute values for many of the instrument's underlying parameters, which means that it's a hybrid of a synth programmer and a modulation matrix. It offers 18 sources (some of which are bipolar, for a total of 24 options) and you can apply any combination of these to each of the 41 destinations, which include all manner of things that I hadn't expected. The most significant of these are the cutoff frequency and resonance of the Solo section's unheralded but polyphonic low-pass filter section. This isn't the most powerful filter you'll have ever heard, but it can shape a huge range of sounds ranging from smooth polysynths to some surprisingly powerful monosynth patches. Unfortunately, while the filters are resonant and will even oscillate, the lack of MIDI Note Number as a modulation source means that they can't track the keyboard. I discussed this with the chaps at Waldorf and was pleased to learn that this was already on the wish list for a future update.

Returning to the matrix itself, you can send a single modulation source to multiple destinations and multiple sources to a single destination, while the fifth slot adds an important facility that's missing from the other four: the amount by which its source affects its destination can itself be the destination of the other slots.

In Use

My initial setup for this review comprised the STVC connected to and powered by my MacBook Pro. Once it was switched on, I was pleased to find that the STVC immediately appeared as both a MIDI input and output device on the Mac, but I was disappointed that it neither transmits nor receives audio via USB. Since it's a digital device I had expected USB audio, which would have made it simpler to use in a modern recording environment. I also connected it to a Streichfett via 5-pin MIDI to perform A/B comparisons and immediately discovered that every control other than the octave transposer and the effect selector sends a MIDI CC, as do any changes made in the modulation matrix. Since the STVC and the Streichfett share (as far as is possible) the same CC map, this means that you can use the former as a programmer as well as a controller for the latter. Finally, I connected the gooseneck mic. I soon found that I had to add 21dB to its input gain if I wanted the levels of vocoded sounds to match those of the Strings and Solo patches but, fortunately, the gain range extends from 0 to +30 dB so the necessary headroom was available.

Don't judge the STVC by its factory sounds — there's much more inside once you've learned how to get the best from it.

It was now time to create and save some signature sounds but, before doing so, I stepped through the 51 factory patches to see what Waldorf's programmers had wrung out of the STVC. These contained the expected string ensembles and pads, VP330-inspired choruses and vocoder setups, plus some organ-esque patches, a handful of monophonic leads and basses, as well as some polysynth patches that include a dual-oscillator 'fifth' patch created by using the matrix to offset the pitch of one section against the other. (That was unexpected!) Nonetheless, the underlying character was quite similar throughout so I attempted to push its boundaries by making more use of the matrix and the Solo's filter section. For example, I directed velocity to the filter cutoff frequency and the volume of the sound, aftertouch to the vibrato depth, expression to the Solo/Strings balance, and the modulation wheel to the reverb mix to create a touch-sensitive polysynth patch that I could morph into a cathedral organ using the pedal and mod wheel. On a less ambitious occasion I emulated the Godwin 749 String Concert by using four slots to program the speeds and depths of the LFOs that determine the ensemble effect. But I often wished that I had more slots to play with. Imagine what would be possible if the matrix were large enough to program the starting values of all of its destinations and to modulate them. I discussed this with Waldorf, and they responded that they're not sure if it's possible to increase the number now, but that they might look into it. Fingers crossed.

The STVC measures 740 x 280 mm and weighs in at a reassuring 7.5kg.

Anyway, by the end of the review I had obtained some totally unexpected lead synths from the STVC, as well as patches ranging from bass pedals to percussive keyboard sounds to delicate musical boxes and chimes. I also found that there's a much wider range of vocoded sounds lurking inside, ranging from 'Mr Blue Sky' to some weird and wonderful results when Freezing low amplitude vocal signals. My favourite use of this was to Freeze a short snippet of my voice and use this as a complex filter to modify the carrier generated by the Strings. The results could be gorgeous so, if I were allowed to ask for one more improvement to the STVC, it would be the ability to save the Freeze coefficients as part of a patch. Unfortunately, this wasn't planned when the STVC was designed and its single Freeze plus its 126 patch memories consume all of the non-volatile memory, so I guess that I'll have to wait for an STVC 'Pro'. Nonetheless, my advice would be that you don't judge the STVC by its factory sounds — there's much more inside once you've learned how to get the best from it.

Happily, neither of the bugs that I discovered when reviewing the Streichfett have survived in the STVC, although I encountered one new one during the course of this review. The last destination in the matrix is called Bottom. The manual didn't tell me what this should do and, no matter what I tried, I couldn't get it to affect anything. I contacted Waldorf who told me that I had discovered a bug. When fixed, this will be a bass boost, and the update should be available before you read this.

The only other thing to mention is the STVC's commendable lack of aliasing. Sure, you can create artefacts on a handful of very high notes by setting both the Solo filter cutoff frequency and resonance to maximum and then shifting both the keyboard and the pitch of the sections to their maxima, but that's not something that you would ever do in normal use.

Conclusions

I suspect that many prospective purchasers will view the STVC as a direct alternative to the recent Chinese copy of the Roland VP330 but, with its velocity and aftertouch-sensitive keyboard, far more flexible string synthesis, mono- and polysynth capabilities, formant shifting, morphable sounds and carriers, modulation matrix, onboard effects, patch memories and more, it's a much more powerful instrument. As for its price, people are now trying to sell vintage string synths and vocoders for eye-watering sums and, as I write, a Solina, two RS505s and a VP330 are all on sale in the UK, each with an asking price in excess of £3000$3000. At this point (and provided that you don't suffer from rabid anti-digital personality disorder) the STVC begins to look like excellent value. Furthermore, since it's not in excess of 40 years old, the chances are that it will also prove to be more reliable than any of them. It might be unassuming, but there's a lot here to like.

The Rear Panel

The STVC's rear panel starts with unbalanced stereo quarter-inch audio outputs and a 3.5mm headphones output that carries the same signal. Next to these, there's a dual-purpose TRS quarter-inch socket that can act as an expression pedal input or as a monophonic audio input (although not both at the same time), while a conventional quarter-inch sustain pedal input applies a permanent sustain rather than an extended piano-style release.

Alongside these you'll find a USB 'B' socket that acts as both MIDI In/Out and as the input for the supplied 5V PSU. Since there's no other way to get power to the STVC it would have been good to see some sort of cable stress relief here but, even were this provided, I don't feel that a USB connector is suitable for rock & roll. The final two sockets are 5-pin MIDI In and Out.

System Settings

In addition to the matrix, the Tweak function accesses a short menu of System settings. Many of these determine the instrument's MIDI configuration, including the single MIDI CC accessible as a matrix source, and what the STVC transmits when you program and play it: control panel changes, program changes, as well as notes, wheels and aftertouch. Tuning is also carried out here, with controls for transposition, master tuning, and the pitch-band range. (The Streichfett had no tuning capabilities, so this is a significant improvement.)

Further items allow you to set up the microphone, with parameters for input gain, a high-pass filter to remove rumble, an on/off switch for the 2.4V phantom power and the Freeze threshold. Another determines whether the line input acts as an expression pedal input or accepts audio for use as either the vocoder's carrier or modulator. The final system menu allows you to dump sounds, save the global settings and the current Freeze signal, restore the factory sounds, and upgrade the firmware.

The Modulation Matrix

Source

Destination

OFF

Vibrato depth

Set value

Vibrato rate

Add constant

Strings section registration

Subtract constant

Strings EQ setting

Aftertouch +ve

Strings oscillator shape

Aftertouch -ve

Strings Attack

Mod wheel +ve

Strings Release

Mod wheel -ve

Solo/Strings balance

Pitch-bend +ve

Master volume

Pitch-bend -ve

Master pitch

Expression pedal +ve

Strings pitch

Expression pedal -ve

Solo pitch

Velocity +ve

Solo Tone

Velocity -ve

Solo filter cut-off frequency

Selected MIDI CC +ve

Solo filter resonance

Selected MIDI CC -ve

Solo Attack

Vibrato LFO

Solo Decay/Release

Tremolo LFO

Initial Tremolo rate & depth

Chorus LFO

Tremolo depth

Ensemble low speed LFO

Tremolo rate

Ensemble high speed LFO

Solo portamento rate (monophonic Tones only)

Animator LFO

Reverb room size

Phaser LFO

Reverb mix

Random value

Phaser LFO rate

Random value on new note

Phaser depth

 

Animate LFO rate

 

Animate depth

 

Chorus LFO rate

 

Chorus depth

 

Ensemble low LFO rate

 

Ensemble low LFO depth

 

Ensemble high LFO rate

 

Ensemble high LFO depth

 

Vocoder formant shift

 

Vocoder carrier jitter (Strings only)

 

Vocoder adaption speed

 

Vocoder modulator leakage

 

Vocoder Freeze speed

 

Vocoder Freeze position

 

Matrix slot 5 amount

 

Bottom

Pros

  • It offers the same rich string ensemble and choral sounds as the Streichfett.
  • The Solo section has double the polyphony of the Streichfett.
  • There are two new monosynth Tones in the Solo section.
  • There's a polyphonic resonant low-pass filter section lurking inside the modulation matrix.
  • Hang on... there's a modulation matrix!
  • The vocoder is far more flexible than most vintage instruments or their copies.
  • The range of sounds available is considerably wider and more useful than you might imagine.

Cons

  • You can only save one Freeze (vocoder coefficient sample) within the STVC itself.
  • You can't separate the Strings and Solo sounds using the STVC alone.
  • It would be nice if the modulation matrix were larger.
  • Phantom power is limited to +2.4V.
  • There's no audio over USB.
  • For many, a USB power supply won't be suitable for stage use.
  • The manual lacks detail in a few places.

Summary

If you're interested in string synths and vocoding you should take the STVC very seriously. But don't limit yourself to using it like a vintage instrument — it's capable of much more.

information

Published October 2020

From the same manufacturer