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Sonic Dune 1Q73

Mic Preamp & EQ
By Bob Thomas

Sonic Dune 1Q73

Serbian company Sonic Dune have augmented the classic Neve 1073 design to offer the user both practical and tonal options.

Based in Ćuprija, Serbia, Sonic Dune’s debut product wears its ancestry on its sleeve: their 1Q73 mic preamp and EQ is clearly based on Rupert Neve’s classic 1073 design. That said, Sonic Dune have added several interesting options not found on the original — or, in fact, on any of the other 1073 homages I’ve encountered.

Overview

The 1Q73’s transformer-balanced, Class-A circuitry is contained in a rather hefty 1U rackmount enclosure, whose off-white front panel carries a familiar-looking set of controls, augmented by three function switches. An unbalanced DI input sits on the extreme left of the fascia and features two separate JFET buffers that feed the 1Q73’s mic input transformer and its rear-panel unbalanced DI output. Next, a Neve-style sensitivity switch (with a range of -25 to -75 dB in 5dB steps) gives the mic input an overall gain of +75dB. The 1Q73’s line input is attenuated by 35dB before it reaches the input transformer, placing unity gain at the -35dB position, with -10 to +40 dB of available adjustment. As in the original 1073, this switch also has an off position between -50 and -55 dB, in order to avoid a loud switching transient when a second gain stage comes in at -55dB.

A block of four and a line of two rectangular buttons take care of the input settings. The LoZ button switches the input transformer’s two 600Ω primary windings between series and parallel operation, to give a choice of microphone input impedances of 1200 and 300 Ω, respectively. Its neighbour inserts a 25dB pre-transformer pad into the microphone input, and separate switches activate the DI and line inputs. In the group of two, the first button reverses the polarity of the output and the second switches 48V phantom power to the balanced rear-panel microphone input XLR.

Above these last two buttons sits a small black toggle switch, marked ITSLoad (Input Transformer Secondary Load). This places either a 180pF electrolytic capacitor or a 12kΩ load resistor across the input transformer’s secondary winding. The 180pF cap is there to help ensure a flat response in the audio range whilst, in combination with the resistive load of the circuitry that it is driving, to dampen any ‘ringing’ at an ultra-high frequency. A byproduct of switching in the 12kΩ load is 0.75dB attenuation of the input signal and a gentle shelving roll-off of 1-1.5dB above 18kHz.

Although this ‘either/or’ capacitor/resistor setup is unusual, there’s some historical precedent: some earlier Neve modules had a 12kΩ secondary load resistor permanently in circuit, with the 180pF cap being brought in on the -55 to -75 dB positions only. 1073 revisions eventually dispensed with the resistor and placed the capacitor permanently in the circuit.

The next objects of note on the front panel are the unstepped controls for the output level (+25dB max) and the switchable concentric Low/High shelving EQ. The EQ offers ±16dB of adjustment at either 60 or 110 Hz (Low) and at 12kHz (High). The final two function switches, which illuminate when engaged, offer choices that I’ve not encountered before on a 1073-based mic preamp. You can switch the transistor in its Class-A output stage between the original 2N3055 or a more modern TIP41C, and choose either Vintage (discrete) or Modern (monolithic) power-supply regulation.

The final unusual feature sits on the rear, where, in addition to the mic and line inputs and the line and DI outputs, you’ll find a balanced XLR labelled ‘LM Output’. This carries the line-level input signal but attenuated by 35dB, to bring it down to microphone level — it could be useful should you need to connect the output of the 1Q73 (with a microphone as source) or another external unit to a mic-level input.

Opening up the 1Q73 reveals high-quality internal construction. The chassis is divided into two sections, with a toroidal power transformer and one PCB (carrying the power supply and relay switching) occupying one half, with a steel wall separating this from the audio PCB in the other half. Both the power supply and audio boards are laid out with exceptional clarity, each circuit section and its components being easily identifiable. All circuitry in the 1Q73, with the sole exception of one IC in the switching logic section, is made up of discrete components, and those in the audio circuitry, in particular, are of very high quality. The input and output transformers used in the 1Q73 are UK-manufactured modern Carnhill equivalents to the Marinair originals.

The 1Q73 features an unusual but useful complement of outputs, including a line signal padded down to 35dB to mic level, allowing you to feed the signal to other mic preamps.The 1Q73 features an unusual but useful complement of outputs, including a line signal padded down to 35dB to mic level, allowing you to feed the signal to other mic preamps.

In Use

The DI input with its a buffer amps and input impedance of 1.1MΩ (the same as many guitar amps) gives a good solid account of itself, with both six-string and bass electric guitars sounding as they should. Having the buffered DI output available gives you the option of simultaneously recording both preamp’ed and clean-feed signals, or the option of, for example, feeding a further preamp.

Although the line input is padded down by -35dB before the input transformer, the signal sometimes sounded a little too hot to my ears so, if what you’re primarily looking for is the harmonic richness that the output transformer can offer, it pays to watch the level of the signal going into the 1Q73. Again, the attenuated ‘microphone level’ version of the line-level input signal is always available on the 1Q73’s rear panel LM XLR, which means that you’ve got a line-level to mic-level converter available any time you need it.

However, the main reason to consider a 1Q73 is the sound it produces when a mic is plugged into it. Setting it up in the later 1073 topology — with the 180pF capacitor switched across the input transformer secondary (so no 12kΩ load), and with the 2N3055 output transistor in circuit in tandem with the vintage voltage regulation — gave a very close reproduction of a later 1073. That said, to my ears, the 1Q73 sounds somewhat more open, clear and detailed overall than my recollection of original 1073s and of some close recreations I’ve used. Switch in the 12kΩ load (which takes the 180pF capacitor out of circuit) and sounds get slightly darker, but without losing clarity or definition. Incidentally, with the 12kΩ resistor in place (so no cap) you’ll be hearing a recreation of the sound of early Neve modules such as the 1063 or 1290 when you’re working in the -25 to -50 dB area.

The two-band EQ is capable of quite drastic surgery, but it’s better suited to more gentle massaging than serious sculpture. That said, if you want to seriously cut or boost the low end or need to get vicious with the high end, the 1Q73 will do that without ever sounding unmusical.

Life really starts to get interesting when you switch over to the TIP41C output transistor and the modern voltage regulation, at which point the 1Q73 gains a whole new lease of life — the sound appears to clean up considerably around 300Hz (which really helps acoustic guitars), the response to transients seems faster, and there’s a tighter, more focussed feel overall. Much as I like how the 1Q73 sounds when configured in vintage mode, this ‘modernised’ setup (with the 180pF capacitor in circuit rather than the 12kΩ resistor) could very easily become my go-to starting point for recording acoustic guitar.

In its ‘vintage’ settings, the Sonic Dune 1Q73 delivers a warm, smooth, articulate and detailed sound that’s coupled to a richness and depth that you can dial in to taste by driving the input and/or the output transformers harder. Once the more modern options are activated, there’s a tangible clarity in its handling of low-level detail and a sense of space that I’ve not heard in other 1073-inspired preamps.

Dune & Dusted

I‘ve found the Sonic Dune 1Q73 to be a rather special mic preamp. Although it has the DNA and essential character of the classic 1970s Neve design, the input stage, particularly in its -25 to -50 dB range, harks back to the earlier 1063 and 1290. The voicing options, courtesy of the input transformer secondary, output transistors and voltage regulation choices, endow it with a flexibility I’ve not seen in its direct competitors. Coupled with its extremely useful DI and Line/Mic conversion facilities, the 1Q73 is a mic preamp that will tick a lot of boxes for many users.

Although the 1Q73 can produce an accurate facsimile of the revered 1073’s sound, its own unique combination of warmth, weight, richness, clarity, low-level detail and sense of space is what makes it so special — it is those qualities that I’ll miss the most when I have to hand it back. In short, if the 1Q73 is within your budget, you have to hear it!

Alternatives

The 1Q73 is unique, but there are plenty of other high-quality 1073-derived designs, including those by Neve, Rupert Neve Designs, BAE and Heritage Audio. For those on a tighter budget, the Golden Age Project Pre-73 range and Black Lion Audio’s offerings are worth a look.

Pros

  • Superb sonic performance.
  • Vintage and Modern voicing options.
  • Useful additional features.

Cons

  • None.

Summary

Combining a close recreation of the original Neve 1073’s sound with other vintage and more modern-sounding voicing options, the 1Q73 is an extremely impressive and rather special preamp.

information

£1436 including VAT.

sonicdune.com

€1250 (about $1400) plus shipping.

sonicdune.com

Published August 2017