Toft Audio EC1

Photo: Mark Ewing

Despite its modern-looking packaging, this new unit offers a classic sound.

Malcolm Toft is most often associated with overseeing the design of Trident recording consoles during his time at Trident studios. In his new range of rackmount outboard gear, he's combined new technology with circuits based on these old Trident designs, with a view to combining vintage character with modern technical specifications. The Toft Audio EC1 is essentially a mono recording channel comprising a mic/line preamp, a four-band equaliser, and a FET compressor. While the EQ and compressor hark back to the type of circuitry that was widely used in the Trident days (the EQ is exactly the same as in the MTS980 recording console), the mic preamp is based around a highly specified Burr-Brown mic preamp chip for low noise and distortion, and this same chip is used as a front end in a number of high-priced 'designer' preamps.

The EC1 is built into a 1U rack unit fitted with a substantial front panel finished in silver with clear black legending. Both mic and line inputs are provided on the rear panel, and are electronically balanced. As expected, the mic input is on a conventional XLR, though the line inputs and outputs are available on both balanced XLRs and balanced quarter-inch jacks.

There's also an unbalanced, high-impedance (100kΩ) instrument DI input in the centre of the front panel that can accept electric guitars and basses with passive pickups. Mains comes in via an IEC inlet, which also includes a fuse holder and voltage selector for 115V or 230V operation, though the mains switch is on the front panel where it is clearly accessible.

The unit's construction is conventional but sound, and all the ICs are in sockets for ease of servicing — something Malcolm feels strongly about. Many mass-produced units now use surface-mount component technology, which, while very reliable, is rather difficult to work on when it does go wrong. A Burr-Brown INA217 chip serves as the mic input amplifier, while most of the other active components are humble TLO72 op amps, as the designers feel that these still provide the best all-round audio performance, even though some other devices may look more esoteric on paper. Also socketed is the FET that's used as the compressor gain-reduction element. Each compressor is manually set up and calibrated, as FETs don't always have adequately consistent characteristics.

The control panel is logically set out with the mic/line input section on the left, the equaliser next, and the compressor to the right. However, the signal flow doesn't have to follow this path, as the compressor can be switched before or after the equaliser. I feel this is a good feature, as the subjective results can be very different depending on the order of processing. Normally I'd have the EQ after the compressor, but sometimes the other order gives the best musical result. A circular VU meter with the Toft Audio logo handles both output-level and gain-reduction monitoring.

The mic preamp section is controlled by a single knob and three switches, where the knob controls the input gain from 12dB to 60dB (mic) or from -12dB to +40dB (line/instrument). A recessed toggle switch selects mic or line operation, with two further switches for phase inversion and phantom power. A status LED shows when the phantom power is active. As with most high-quality designs, the frequency response extends well beyond that of human hearing, but isn't taken to such ridiculous extremes that it makes it prone to radio-frequency interference in 'real life' applications.

The FET Compressor

As mentioned earlier, the compressor uses a Field Effect Transistor (FET) as its gain-control element, and this functions essentially as a voltage-controlled resistor. Again this design is based on that used in Trident consoles and features four knobs to set the attack, release, ratio, and make-up gain. A toggle switch bypasses the compressor and there's an LED to show when it is active. A similar switch changes the meter function, allowing it to monitor either the output level or the amount of gain reduction being applied by the compressor.

This compressor design has no threshold control, but instead uses the system where the threshold is fixed and the signal feeding the compressor is varied, in this case by adjusting the mic preamp gain. The make-up gain has up to ±20dB of gain adjustment to compensate for the gain reduction imposed by the compressor. The release time, although adjustable via a knob, has a degree of programme dependency so that the actual release time is modified by the dynamics of the material being processed. Ratio is adjustable from 1:1 to 12:1, and the Attack control is also fully variable. Switches are available to bypass the compressor and to switch it before or after the EQ.

If the four-band equaliser looks as though it came straight from a mixing console, that's because it did, though the more usual high and low shelving filters are in this case replaced by sweepable peaking filters, the same as for the two mid-bands. The EQ ranges are 40-650Hz, 100Hz-1.5kHz, 700Hz-10kHz, and 1kHz-15kHz. In all cases, the gain range is ±15dB, and a centre detent indicates the flat position. A bypass switch with status LED takes the EQ out of circuit when not required. Having peaking EQ sections throughout generally offers more control over things like the thump of kick drums, and also makes it easier to add an airy shimmer to the top end without applying unnecessary boost to very high frequencies, as would be the case if a shelving equaliser were to be used.Photo: Mark Ewing

Performance

The mic input stage is quiet and clean, with plenty of headroom and low distortion. It gives the impression of being designed for transparency and clarity rather than for adding some kind of sonic character to the sound, and my own view is that this is the safest way to record. Character can always be added later, but unwanted character is very difficult to remove!

The instrument DI input is a useful feature that's becoming more commonplace, and despite guitars usually being designed to work into a 1MΩ or greater impedance, it works well with most guitars and basses on those occasions where a straight DI sound is suitable. It also makes a good front end for a computer-based guitar-amp modelling plug-in.

The equaliser section is both musical and flexible, with plenty of range and plenty of overlap between bands. I like the choice of all peaking sections, and though a fully parametric equaliser is more useful in theory, it's often the case that a simpler equaliser with an intrinsically good sound will do a better job. Because this design is based on the same Wien Bridge filter circuitry as used in some of the leading '70s analogue mixing consoles, it has a vintage British sound to it. Most evident is that you can use perhaps more EQ boost than might normally be the case without the sound becoming brash.

Although most of us are used to compressors with a variable threshold, the fixed-threshold approach is used in a number of historic designs and works perfectly well once you understand that you have to change the mic/line input gain and ratio to change the amount of compression taking place. Like optical compressors, FET designs have their own character which is different to both optical and VCA designs. The way the attack and release circuits are configured also affects the character of the compression. This compressor comes over as both assertive and musical, and, depending on how much you apply, it can either be charmingly subtle or quite 'in your face'. It doesn't have the same sound as an optical compressor, but rather imparts a tube-like character to the signal being processed.

The Final Word

This recording channel is designed in the UK and then manufactured in China. The outcome in this instance is that you get the benefit of both classic circuit elements and modern technology where that is applicable (such as the mic preamps), but at a UK price point well below that of those hand-built esoteric recording channels that may cost a lot more but deliver little if any extra performance. Indeed, I think that Malcolm Toft has made a wise decision not to slug it out in the 'me too' end of the budget market, but instead has designed what is essentially a very worthy professional product with a true vintage legacy, and one that most serious recording enthusiasts can afford.