This novel preamp design features a variable impedance and slew rate — which opens up a whole new world of possibilities from your mic locker...
Dave Hill is one of the industry's best-known and most highly respected audio electronics designers, whose vast experience started with designing and building synthesizers — and making professional sound recordings — while still at school in America. When he decided to pursue a career in electronics, he enrolled at a local community college... but soon found himself being asked to take over as the course teacher — a role he continued for the next eight years! However, it is Dave Hill's analogue audio products that are of interest to us now, and given the pedigree of his designs under the Summit Audio and Crane Song brands (as well as a lot of bespoke work for several other well known pro-audio companies), anything new from this stable immediately stirs the interest. His latest company, Dave Hill Designs, runs alongside Crane Song and currently has only two products in its fledgling catalogue: a non-linear compressor plug-in, and the Europa 1 hardware mic preamplifier. It's the latter that is the focus of this review.
As might be expected, the Europa 1 is a top-flight product in terms of performance and specification, but it also includes some very interesting twists and unusual features. In fact, the Europa 1 has been designed to enable and encourage creativity, by providing a lot of flexibility in the sonic palette it offers the user. All of Dave Hill's designs are the result of a very thoughtful approach to audio electronics, combined with painstaking auditioning. He likes to find new ways of achieving things, rather than using standard approaches, and is a firm believer in listening to the results as a product is developed, because, as he says, "There is no 'sounds good' measurement”.
The Europa 1 is a single-channel, 1U rackmount unit, which extends roughly 225mm behind the rack ears, and consumes a modest 25W (the unit does get slightly warm after several hours' use). The rear-panel connections are limited to an IEC mains inlet (with integral fuse-holder and voltage selector), and two XLRs; one for the mic input and one for the line output. The front panel more than makes up for this simplicity with no fewer than five distinctive green, rotary controls, five black toggle switches, a two‑digit display, a 10cm-long bar-graph meter, and a front-panel instrument input socket. That's pretty busy for a simple mic preamplifier!
Starting at the left-hand side, the first of the toggle switches turns the power on and off, while the next activates phantom power. Toggle number three provides polarity inversion ('phase'), while the fourth switches the input impedance between 'High-Z', 'Mid' and 'Low' options. The High-Z option provides around 200kΩ when the gain is above 12dB, and about 18kΩ below. The Mid setting provides the standard 2.2kΩ, and the Low provides 300Ω. Modern mics with electronic output drivers reveal little audible change with different load impedances, but all dynamic mics and any capacitor mics with output transformers react audibly, in different ways. So the input-impedance switch can be thought of as a kind of tone control that reacts differently with different microphones — which means more creative options! The instrument input, selected with the last toggle switch, has an input impedance of 1.2MΩ. All switching functions (with the exception of the phantom power) are performed by sealed relays.
The Europa's maximum output level is +24dBu and, with the gain set to zero, it will accept +24dBu on the mic input, too. So by selecting the high input-impedance mode and dialling the gain down to zero, you have a straightforward line input and can use the Europa 1 to colour line signals during mixdown.
Stretching out horizontally above the five toggle switches is a generously proportioned meter display, scaled with a yellow LED at the centre point to indicate 0VU (+4dBu). Extending to the left are 20 green LEDs showing the level down to -25VU (-21dBu), while to the right another 20 red LEDs show the level up to +20VU (+24dBu — the unit's maximum output level). If you hit the end-stop in the red region, you've got your gain structure very wrong... but the reason why the meter provides 1dB resolution through the 20dB headroom margin is because the signal-processing features (see below) all become much more pronounced with high signal levels.
The preamp's gain setting is indicated by the two-digit numerical display in the centre of the front panel, and this is controlled by the adjacent rotary encoder switch. In mic mode, it provides a gain range from zero to 66dB in precise and repeatable 1dB steps — the click of a relay at the 12/13dB change-over is where the input impedance alters in High-Z impedance mode. When switched to instrument input, the gain range is restricted to 0-30dB.
The next rotary control is an 18dB/octave, high-pass filter switch, providing a comprehensive set of eight turnover frequencies, plus a bypass. The panel markings offer 150, 133, 120, 100, 83, 66, 53 and 34Hz, and off.
While all of the controls I've described so far are pretty conventional, the last three rotary controls are much more 'off the wall'. The Speed control determines the preamp's slew rate — that is, how quickly the preamp responds to the input signal's changing dynamics — and is scaled simply from 'Slow' to 'Fast' in nine steps. (More on that in a moment.) The even and odd harmonic controls also both have nine steps, scaled from 0-8, and in both cases, the higher the setting, the more harmonic distortion is introduced. These three controls process the signal in the same order as their panel presentation, left to right, and consequently they interact with each other to some degree.
The build quality of the Europa 1 is superb, with a torroidal transformer mounted towards the front of the unit feeding a compact linear power supply (with unusually large reservoir capacitors) on the main circuit board. Surface-mount components dominate the main PCB, which is arranged along the back half of the case. A small vertical card behind the front-panel controls and displays links to the main board via a neat ribbon cable.
The preamp uses 91 discrete transistors (I didn't count them — it says so in the manual!) in a Class-A topology, although there are also several high-end op-amps on the PCB, too. A THAT 5171 chip provides the switched gain-control; this is basically a digitally controlled, balanced, switched-resistor system, using FETs to turn the resistor stages on and off. A THAT 2181 VCA chip is sited amongst the circuitry associated with the speed and harmonic-generation stages.
The published specifications for the Europa 1 are rather limited, but I was able to confirm an exemplary performance using an Audio Precision x515 testing system. With minimum gain selected, I measured the frequency response as extending from 7Hz to over 100kHz (at the -3dB points), the high-end turnover falling to about 25kHz when set for maximum gain (this change in roll-off frequency reveals a typical gain/bandwidth trade-off). Although the front-panel high-pass filter frequencies and those listed in the handbook differ slightly, the curves are very tidy and musically well-chosen. The noise floor is generally very clean and the few mains-related harmonics visible (but inaudible) on an FFT plot remain below -120dBu at minimum gain, and well below -75dBu even at full gain. The published EIN figure is -127.5dB, but I measured a slightly better performance from the review model, at -129.5dB (full gain, 20kHz bandwidth).
The Europa 1 is an unusual preamp. With the Speed control set to fast, and the Harmonics controls set to off, this is a very clean, neutral, modern-sounding device, easily able to hold its own in comparison with the likes of GML, Millennia and other high-end preamps known for their transparency and natural sound. On the other hand, dialling in some even and/or odd harmonic distortion brings in delightfully subtle musical colour that can really help to bring out the character and body of acoustic sources.
Winding up the Even Harmonics control tends to make the sound seem a little thicker and richer, but it's quite a subtle effect below about halfway, becoming much more obvious and with more upper-harmonic colouration above halfway. Increasing the Odd Harmonics control tends to make the sound brighter and more edgy, and with the control above about halfway it also seemed to introduce a little low-lift compression, making lower-level signals slightly more audible. There's obviously a lot going on here, and it takes a while to really get to grips with all that's on offer — but the use of switchable controls means that different settings can be compared easily, and favourites logged for future use.
The Speed control takes more getting used to than the rest, because its action is very unfamiliar — to me, at least. As the frequency plot reveals, at extreme settings it causes the high end to be rolled off quite dramatically — but only for the loudest signals, leaving lower‑level signals completely unaffected. In practice, this means that turning the control back from fast tends to subdue, and eventually kill, loud signal transients (the transient information being inherently high in frequency). In the process, it lends the preamp a distinctly vintage character, varying from subtle to blatant.
Clearly, this control is most effective when working with loud and transient-rich signals, such as snare drums, for example. And by combining the application of the Speed control with the Odd Harmonics control, it is possible to shape the sound of snare drums in a range of creative and musical ways, for effects ranging from fast and snappy to fat and chunky.
However, the Speed control is also surprisingly useful with cleaner sources too, such as acoustic guitars, and even vocals. Applied to male vocals, just backing the control off from the fast position by a few clicks helped to give the impression of a sound being captured with a vintage valve mic instead of the Neumann TLM103 that was actually in front of the performer. Adding a little even-harmonic distortion really completed the effect, much to the delight of the vocalist! This is a very powerful and creative tool indeed, and one that quickly becomes utterly addictive.
There aren't many truly 'versatile' mic preamps — most have a consistent and recognisable character, and generally you choose one unit instead of another because of its inherent sound: a Neve clone instead of a GML, perhaps, or a Universal Audio 610 instead of an Audient. The ability to introduce some harmonic distortion in a preamp has become popular in recent years, with products such as Audient's HMX 'harmonic sculpting technology' and SSL's VHD 'Variable Harmonic Drive' circuitry, for example. However, Dave Hill's Europa 1 goes far beyond these relatively simple ideas and provides considerably more flexible and creative options, both in harmonic control and — perhaps more importantly — with the remarkably useful slew-rate control feature.
This is a truly impressive product, and one that is going to become extremely popular. It's well worth checking out if you are thinking of expanding your mic-preamp armoury.
Most preamps that compare directly in price to the Europa 1 are dual-channel units, although there are a few single-channel devices that are worthy of comparison and consideration — albeit few that can match the sonic-chameleon nature of the Europa 1.
The Universal Audio LA610 MkII is fractionally more expensive, but is a classic design, combining the valve-based compressor and preamp stages from Bill Putnam's now legendary 1960s recording console. A more modern take on a similar idea is the Empirical Labs EL9 Mike-E, again combining preamp and compressor — and providing a useful palette for sound colouring, thanks to its unique saturation facilities.
Raising the budget slightly brings the Little Labs LMNOPre into contention, a very interesting preamp with some unusual features. If the budget is flexible enough, the Grace Design M103 channel strip might also be an attractive option, as would be the Millenia TD1 recording channel, the latter offering the user the choice of valve and solid-state signal paths in the same box.
Slightly less expensive options (if you already have a 'Lunchbox' frame) include the classic Neve 1073LB, and the Anamod Audio Realios 9033 and 9031 units, the last being based on a similar design to the Helios Type 69 500-series Lunchbox module. Amongst the free-standing units priced slightly below the Europa 1, the Phoenix Audio DRS1 is another contender, along with the Avalon M5, Great River ME1NV and, for more blatant sound character, the Chandler Germanium Pre/DI.
We've placed a number of test plots from the Audio Precision Analyser Hugh used during this review on the SOS web site at /sos/jul11/articles/davehilleuropa1media.htm