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Focusrite Platinum Voicemaster Pro

Recording Channel
Published January 2003
By Paul White

Focusrite Platinum Voicemaster Pro recording channel.Photo: Mark Ewing

The Platinum Voicemaster Pro updates the original Voicemaster concept, adding new features as well as design improvements.

With so many areas of the traditional recording market being encroached upon by software, manufacturers are turning to 'safer' products such as voice channels, microphones and loudspeakers, none of which are likely to be replaced by plug-ins in the near future! Focusrite have a long tradition of building high-end mic preamps and analogue processors, and of course in recent years they've made a big impact in the home recording world with their Platinum series. But, as the Platinum range already includes a number of recording channel products, you might reasonably ask what a new model might offer that the existing ones don't. Nevertheless, the Voicemaster Pro does have some new tricks up its sleeve, not least a selection of creative 'flavour enhancers' in the form of its Tube Sound and Vintage Harmonics sections. Some of the features will be familiar from other devices in the range and, indeed, some share common circuit design, but, in this particular incarnation, the Platinum offers just about everything you could ask for in a channel strip, plus a zero-latency monitoring section for working with soundcard systems. It is interesting to note that only the Class-A preamp circuit used in the original Voicemaster remains unchanged.

Focusrite Voicemaster Pro £399
  • Comprehensive range of processing sections.
  • Good audio quality.
  • Cost effective.
  • Expander compromises sound quality in some situations.
  • Vintage Harmonics section could use a variable Depth control.
Any criticisms of this unit are minor compared to its advantages, especially when its price is taken into consideration. The new creative processing sections are particularly interesting


The 2U Voicemaster Pro can accommodate line, instrument and mic signals and features seven stages, the first of which is a Class-A preamp built using discrete components as opposed to off-the-shelf ICs. This incorporates a variable-frequency low-cut filter, a phase switch and mic/line switching. When an instrument jack is inserted, the mic preamp is overridden. Standard 48V phantom powering can be enabled from the front panel, but there's no phantom power warning LED, which I'm not entirely comfortable about. All sections other than the preamp (for obvious reasons!) have bypass buttons with integral status LEDs. Improved input level metering now has six LEDs, though users should note that it is calibrated in dBFS (digital full scale) as it relates to the maximum input level of the optional internal A-D converter, which is around +22dBu not the usual +4dBu of the analogue world. To work at a nominal +4dBu, preserving headroom for EQ'ing and so on, a suitable meter setting would be around -20dBFS, which means only one or two LEDs on the meter will be illuminated.

A key feature of earlier Platinum devices has been the use of high-performance optical gain control devices in the dynamics processing sections, and here there's an optical expander following the mic preamp, as well as an optical compressor. The expander functions as a 'soft' noise gate to remove low-level noise or spill during pauses in the wanted program material, but sitting between this and the compressor is a completely new stage called Vintage Harmonics. This is quite different to the tube harmonic simulator and can be switched before or after compression. As the manual describes it, the aim is to capture some of the effect achieved by playing back a Dolby encoded tape with no decoding, which results in an artificially bright, compressed high end, especially on lower-level sounds. To achieve this, the circuit splits the audio into three frequency bands, then applies variable amounts of compression to the mid-range and high end while leaving the low band untouched. Only two threshold controls, one for the mid-band and one for the high band, are needed to set up this section. The compressor works to increase the gain when the audio signal falls below the threshold so there is no gain drop when compression is applied and no processing when the signal exceeds the threshold. This way only low-level mid-range and high frequencies are affected. A Depth switch allows for two intensities of processing.

The Voicemaster Pro's zero-latency monitoring facilities include a useful effects loop for incorporating, say, a monitor reverb unit.The Voicemaster Pro's zero-latency monitoring facilities include a useful effects loop for incorporating, say, a monitor reverb unit.Photo: Mark EwingThe compressor is designed to be simple to operate and so has no ratio or attack time constant knobs. Instead, it has switchable Hard Ratio and Slow Attack, along with a pre/post-EQ switch. The only variable controls are for Threshold, Release and Make-up Gain. Opto circuitry in a Class A configuration is used for gain control, offering lower distortion than most VCAs. Next in line is the Tube Sound circuit, which has appeared before in the Platinum range and uses FET circuitry to introduce harmonics dependent on drive level, simulating the way a valve works when driven hard. As the drive increases, second harmonic is added, followed by second and third harmonic and finally, at higher drive levels, fifth harmonic as well. Excessive use of harmonic generation can result in the sound becoming rough or aggressive, so a Tone control is used to confine the harmonic generation process to frequencies below its setting (variable between 4.5kHz to 30kHz).



Also familiar to Platinum fans will be the Voice Optimised EQ, which comprises four rather unorthodox bands. Breath acts as an 'air' control, applying a wide cut or boost quite high up the audio spectrum (switchable from 10kHz to 16kHz). The Mid control is fixed at 1.3kHz, but unusually has a narrow response (high Q) when used in its cut position and a wider, more gentle response when used for boosting. Also affecting the mid-range is the cut-only Absence control which, predictably, functions as a kind of 'anti-presence' EQ by digging a notch at 3.9kHz, where vocal harshness often resides. Like the Mid EQ, the Warmth control features a wide boost/narrow cut response, but is also tunable over the range 120Hz to 600Hz.

After the EQ comes a de-esser, which, rather than ducking the whole signal when sibilance is detected, simply notches out a narrow band of frequencies between 2.2kHz and 10kHz, as dialled in by the user. A Listen button enables the side-chain to be monitored so that the sibilance frequency can be more readily identified, and a Threshold control sets the level of sibilance at which the process becomes active.

The output section features a large, moving-coil level meter and a level control knob, plus a master bypass that takes all processing off-line and turns off the status LEDs in the individual section bypass switches. Also in this section are the zero-latency monitoring facilities, which provide an easy way to listen to a mix of your soundcard's output and your vocal (or instrument) being recorded via the Voicemaster Pro at the same time. Furthermore, the output of an effects device, such as a reverb unit, can be fed into the Voicemaster Pro to add an effect to the headphone monitor signal without it actually being recorded. A balance control sets the relative voice/backing track balance and a headphone level knob is provided next to the headphone jack.

Ins & Outs

The rear panel includes an expansion slot for the optional digital output card, which works at 24-bit resolution and at sample rates of up to 96kHz. There are switches for 44.1kHz, 48kHz, 88.2kHz and 96kHz operation (as well as a word clock input) and the output is on a coaxial S/PDIF connector. A balanced jack on the rear panel, labelled ADC Ext Input, enables an external analogue signal to be routed through the spare channel of the stereo converter, so it's easy to use a pair of Voicemaster Pros sharing one converter. To make connection to a soundcard easier, both input and output jacks are provided (stereo) so that the Voicemaster Pro can sit in line between the soundcard's output and the monitor amplifier.

A mono effects send (unbalanced, before the master output level fader) and a stereo effects return (balanced) are included so that you can hook up that old reverb unit for monitoring. The main outputs are on both balanced jack (-10dBV) and XLR (+4dBu) with a further XLR providing an output from before the de-esser. Both mic and line inputs are available on the rear panel, with mic and instrument inputs located on the front panel, and there are also insert send and return jacks that enable other processors to be inserted directly after the preamp, before the rest of the processing chain.

On The Session

One of the most important tests of any processor, and one that tends to get overlooked, is how well it does nothing! In other words, with the processing switched in, but set so as not to respond to the input, the signal quality should be unchanged when the master bypass button is pressed. The Voicemaster Pro fares well in this respect, except of course for the Vintage Harmonics section where some low-level processing always takes place when the section is active.

The mic preamp is electrically quiet and clean sounding, yet I suspect it flatters slightly in some mysterious way (not that that's any bad thing!), and it also works well for DI'ing instruments such as guitars and basses where this is artistically appropriate. Moving along to the expander, this works predictably and smoothly in normal use, but I found that if I set it so that the sound spent any length of time in the middle of the gain-reduction range, the sound quality became rather gritty. This is to be expected at very short release times, as the expander can switch on and off very rapidly, giving the impression of distortion, but tested with a slowly decaying guitar chord at a medium release setting, the same grittiness could still be heard. In normal use with vocals this shouldn't be a problem and, in any event, it still works more smoothly than most gates, but it might just be audible at the tail end of a decaying guitar chord or similar sound where there's enough amp noise present to warrant a higher than usual threshold setting.

I wasn't quite sure what to expect from the Vintage Harmonics section, but I soon found out that it could be very flattering if applied carefully, especially in the high band. Low-level noise is exaggerated to some extent, because of the compression added to low-level signals, and this is more pronounced at the higher depth setting, which left me thinking a variable depth control would have been more useful. At the lower depth setting, the high band adds a pleasant breathiness to vocals and also adds shimmer to guitar parts, so it's definitely a feature worth having.

The compressor held few surprises, as I've met this design before, and, on the whole, it does a great job without burdening the user with too many controls to adjust. It works fine for general vocal control and can also be used to impart more attitude if the harder ratio setting is chosen. On guitar and bass, the slower attack setting creates a nice percussive character to the start of notes as well as evening out the overall level. As a compromise between flexibility and ease of use, I think Focusrite have got this dead right — though the compressor tends to flatter, it doesn't impose too much of its own character on the sound.

While the original Voicemaster had a fairly simple Tube Sound section, this Pro version uses a far more elaborate tube simulation circuit, coupled with a Drive LED that changes from blue to green to red, depending on how hard this virtual tube is being driven. Used too extravagantly, the effect is a little like one of the new breed of valve preamps that exaggerates the effects of tube distortion, but at modest settings it can add a useful degree of low-end density — if the filter is used carefully to adjust the tone, the effects can be kept away from the upper mid-range and high frequencies. If you need enhancement up there, the Vintage Harmonics section works nicely in conjunction with the Tube Sound section.

I like the idea of an EQ designed specifically for vocals and, in most respects, this one works extremely well. It sounds musical, it's easy to adjust and it provides plenty of control range. In fact the only thing I disliked was the effect of the mid-range control used in boost mode, which seemed guaranteed to make any voice sound nasal and honky — though the designers say they added it because some dance music producers actually want this sound! Of course, in cut mode it removes these same characteristics, making the cut side of the control very useful indeed. Even so, I feel it would have been more useful to make the Absence control both cut and boost, so as to allow it to add presence where needed.

Also worthy of praise is the de-esser, where the side-chain Listen function makes it incredibly easy to tune into the frequency band where sibilance is causing problems. Once this has been located, you only need to adjust the threshold control to pull down the offending sounds, and this can be accomplished without trashing the overall vocal tone. Very nice indeed.

That leaves the master section, which is pretty straightforward, though adding a send and return to allow a digital reverb to be used on the headphone monitor mix is a neat touch. Zero-latency monitoring via hardware is nothing new, but it is well implemented here, with both input and output connections to save the user having to make up any special split cables. There's plenty of headphone level and the general quality of the headphone sound is good.

Control Functions

Focusrite Platinum Voicemaster Pro.

1: Class-A Preamp. This handles mic, line or instrument signals and offers variable gain, variable low-cut filter (30-400Hz) and switchable phase inversion. Phantom power is available, and the instrument input takes priority over the mic input when connected. There's up to 60dB of gain, and a six-section LED meter, calibrated for digital full scale, shows the input signal level, as well as providing a clip warning.

2: Optical Expander. This works like a soft noise gate, attenuating signals that fall below the threshold. It includes a six-section gain-reduction meter and controls for threshold and release time.

3: Vintage Harmonics. This section uses selective 2:1 compression below a user-defined threshold for both the mid-range and high frequencies. You can use this to add density and sparkle to a sound, rather like playing a Dolby A tape back with the Dolby switch turned off. Because the thresholds in the two frequency bands are variable, you can be as subtle (or otherwise) as you like, and the circuitry is designed so that no gain loss is suffered due to the use of compression — below-threshold signals are lifted rather than above-threshold signals being attenuated. Used with the Depth switch engaged, the degree of enhancement is more pronounced, and the effect may be switched before or after the compressor. Two meters show the gain boost in the two separate bands, and a bypass button is provided.

4: Optical Compressor. Unlike vintage optical compressor designs, this one has a very fast response time, but still appears to retain some of the control law non-linearities that make optical compressors sound musical. The control system has been simplified so that there are rotary controls only for threshold, release time and make-up gain. The compressor may be sited before or after the EQ and features two ratio settings and two attack time settings, both accessed by switches.

5: Tube Sound. This simulation of valve overdrive features variable drive and an indicator LED which shows how much drive is being applied to the harmonic generation circuitry. The Tone control allows the added harmonics to be progressively confined, down to 4.5kHz, when a warmer, smoother tonality is required.

6: Voice-optimised EQ: this is a four-section equaliser with two unorthodox mid-range controls. The Breath control affects the very high frequencies that create the sense of 'air' around a sound, while Warmth deals with the low range of the voice, rather than the traditional bass register. The Mid control is designed to address the part of the vocal spectrum associated with clarity, while Absence allows harshness in the 3.9kHz range to be notched out.

7: De-esser. A process for singers who suffer from overly emphasised 'S' and 'T' sounds. This version notches out only the offending frequencies and so has fewer side-effects than one that affects a wide band of frequencies. The only controls are for cut frequency and threshold. The Listen button monitors the de-esser side-chain, making it easy to use the Frequency control to home in on the problem sibilance.

8: Zero-latency Monitoring. These facilities allow the performer to hear the 'live' signal from the Voicemaster Pro mixed with the soundcard monitor out and with an optional vocal effect, such as reverb. This avoids the distraction of listening to your voice in the headphones delayed by the computer's latency.

9: Output Section. A large level meter reads peak levels and shows digital full scale at its maximum point. When working with +4dBu analogue equipment, 0dBFS corresponds to around +22dBu, as this is the highest level most serious audio interfaces and soundcards expect to see. A master bypass switch defeats all the processing sections, and an ADC Lock LED shows when the internal A-D converter is locking to an external word clock source.

Pro Or No?

The Voicemaster Pro is capable of clean, quiet amplification, or it can be used to radically reshape a sound via its various processing sections. In the context of voice recording, this means you can create a useful range of vocal characters without having to switch microphones. In particular, there's plenty of control over low-end warmth and high-end air and sizzle, while the compressor evens things out and makes vocals sound more confident. The only section I have any reservations about is the expander, and then only when used with noisy sounds that might have a very slow decay, such as guitar. It works fine on vocals and is certainly a lot kinder to the sound than a regular gate.

Given its extremely attractive UK price, its diverse processing abilities and the option of fitting an affordable digital output card, the Voicemaster Pro has to be seen as great value. It's by no means the only good, affordable recording channel out there, but it certainly deserves its place on anyone's short list.

infop.gif Voicemaster Pro £399; optional digital output board £129. Prices include VAT.
infot.gif Focusrite +44 (0)1494 462246.
Published January 2003