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Neve 1073 DPX

Dual Microphone Preamplifier
Published March 2015
By Hugh Robjohns

Neve 1073 DPXNeve 1073 DPX

Just when you thought you’d seen every possible permutation of the 1073 preamp, Neve offer up something a little different.

I thought I’d already seen every possible variant of Neve’s 1073 preamp — including the original 1073N ’45–series cassette’, the 1073 DPA and DPD models, and the 1073LB and LBEQ 500–series preamp and partnering EQ modules, not to mention the numerous clones from various boutique manufacturers. But I was wrong, because brand new, and reviewed exclusively here in Sound On Sound, is the Neve 1073 DPX, an enhanced, dual–channel, 2U rackmounting version of this enduringly popular design.

Why another version? As enthusiasts know very well, there is a plethora of original vintage (and clone) modules converted to varying levels of competence and quality into dual–channel rackmounted systems. Perhaps AMS–Neve felt it important to address that sector of the market directly, with a properly engineered version, with all the panel legends the right way around — but they’ve done more than that, because this version boasts some very useful additional features.

Design & Construction

Naturally, the heart of the 1073 DPX is the familiar 1073 preamp/EQ, with the same circuitry, input and output transformers manufactured to the same spec as the Marinair originals, the same dual–concentric Grayhill switch/pot functions, and the same control legends, knobs and push-buttons. Internally, it’s mostly constructed using surface–mount device (SMD) technology, based closely on the company’s reworked 1073N module (http://sosm.ag/neve-1073n).

In brief, the distinctive gain switch accommodates mic signals between –80 and –20 dBu in 5dB steps, and line signals from +10 to –20 dBu, with all gain switching performed by sealed relays. The EQ section provides a high shelf at 12kHz, a switchable mid–section (centre frequencies of 0.36, 0.7, 1.6, 3.2, 4.8 and 7.2 kHz), and an adjustable low shelf (corner frequencies of 35, 60, 110 and 220 Hz). In addition, a separate 18dB/octave high–pass filter can be switched between off, 50, 80, 160 or 300 Hz. Two push-buttons switch the EQ in or out of circuit, and invert the output polarity.

Not many of the various 1073 clones offer headphone monitoring facilities.Not many of the various 1073 clones offer headphone monitoring facilities.The tiny power inlet connects to an included external 48V DC power supply,.The tiny power inlet connects to an included external 48V DC power supply,.The classic 1073 EQ controls.The classic 1073 EQ controls.Enhancing this core vintage functionality, the DPX can be fitted with an optional digital I/O card (expected around the middle of the year) which provides both high–quality internal A–D conversion of the outputs as well as D–A conversion to feed the line inputs. This allows the 1073 DPX to be integrated easily for creative outboard processing within a digital workflow. To that end, the first of a pair of buttons on the left of the front panel selects the (optional) digital input in place of the normal analogue mic or line inputs, while the second button selects the front or rear–panel analogue inputs.

Rear–panel connectivity includes four XLRs for the separate mic and line inputs plus two more for the main analogue outputs, while four TRS sockets provide balanced insert sends and returns for each channel. On the front panel combi XLRs accept mic and line inputs, while separate TS sockets provide dedicated instrument inputs. A removable blanking plate covers the space allocated for the optional digital card.

Two more push–buttons associated with the main analogue inputs activate phantom power and change the mic impedance (1.2kΩ or 300Ω), while a further pair introduce a 20dB pad and ground lift for the DI input (which takes over automatically when a plug is inserted).

Over on the right–hand side, another pair of push–buttons activates the insert loop return into the output stage, and allows the send signal to be derived pre– or post–EQ. Separate output level controls are provided for each channel, along with a seven–LED meter scaled from –30 to +24 dBu. Pressing the knob inwards toggles the meter between input, EQ–stage and output levels. Another knob determines the volume of the integral headphone amplifier with a full–size headphone socket on the front panel. Again, pushing this knob cycles between monitoring each channel individually, or both in stereo.

Internally, there are two large identical T–shaped PCBs mounted one above the other, each carrying the electronics for a complete channel. The circuitry is laid out differently from the 1073N module, but the individual three–transistor gain blocks, built with conventional transistors, are quite recognisable, as are the three bespoke inductors in the EQ section, and the 2N3055 output transistor. A miniature plug–in module harks back to the original Neve BA gain stages, and appears to be related to the insert send. The big traditional output transformers are mounted near the back of the chassis on one side, carefully orientated to minimise magnetic interaction, and a vacant space on the other side awaits the digital I/O board which connects via an IDC connector.

The DPX is a large (360mm behind the rack ears) and heavy box, and I initially assumed it had an integral power unit. Sadly, this is not the case, and power is delivered from an external 48V DC universal ‘line–lump’ connected via a small coaxial plug. Internal regulators provide the required single–sided 24V DC audio rail and various relay/lamp supply rails. Consequently, the front–panel power button only switches the internal DC supply.

As you’d expect, build quality is superb and audio quality is everything you’d expect of such a revered design. The circuit revisions necessary for relay–switched gain (instead of the original complex and very expensive multi–level switch), and SMD construction, have been well proven in the 1073N module, and serve to improve reliability and consistency of this classic preamp/EQ design without detriment to the definitive sound character.

Verdict

Naturally, the 1073 DPX isn’t cheap, but the reality is that this incarnation is almost half the price of a pair of traditional 1073N cassettes in a rack case, while simultaneously providing much more flexibility. A closer match in terms of functionality is the 1073LB/LBEQ 500–series modules, but even a set of four in a suitable rack would cost more. All in all, this is a very well–conceived package and I’ve had to lock my wallet away to reduce temptation. Even so, I’m not sure I’ll be able to hold out once the digital card is released!

Alternatives

A pair of 1073N modules in a rack would cost much more but offer significantly less flexibility and functionality, while a Lunchbox chassis with 1073LB and LBEQ modules would cost roughly the same but lack the ergonomic loveliness of the original 1073 design. A pair of 1081 modules (with its more advanced EQ section) in a rack will set you back nearly twice as much.

Insider Information

Taking the lid off the 1073 DPX reveals it to be well built. The space at the back-left is for the optional digital converter card. The two output transformers (back-right) are angled relative to each other to minimise magnetic interaction. The DC regulators are in the back–right area of the board (including two high–Wattage dropper resistors). The 2N3055 in the finned heatsink near the middle is the output transistor.Neve 1073 DPX There’s a little daughter card with a BA283–style gain stage built the old–fashioned way to the right of the two larger EQ inductors. (I think it is the insert-send buffer.) The rows of black lumps around the gain switch are the gain–setting relays, and the red bricks behind are the switching relays for the other functions. The Green ‘Marinair’ input transformers can be seen front–left. The BA283 gain stages all use trios of discrete conventional transistors, not SMD versions. The second channel card is identical and sits underneath the first. The optional digital board plugs into the lower card adjacent to the ribbon cable, back–left. (The board below is fitted with the IDC connector, which is absent from the top board). The ribbon you can see in the picture links the two channels’ I/Os, power, and so on.

Published March 2015