The massive 1073 clones shootout

I use to write my blog posts and reviews in Italian but ,since this thread could be of interest for many of you all around the world, i choose to write in English this time and share my experience with this bunch of heavy irons i had the chance to play in my lab.

Everybody knows what a Neve 1073 is but i believe very few of us poor sleepless engineers could ever have a chance to get a real one in the studio, either for insanely high prices of hard to find good shape and trusty units on the market.

I fell in love with the ‘real N’ during Morrissey’s Low in High School sessions in Rome, with Joe Chiccarelli driving the 60 channels Neve VR Legend console at Forum Music Village studios in Rome (Ennio Morricone’s personal workshop since early 70’s). I was called to bring some of my custom microphones for Joe and stayed there for a while during soundcheck and mic placement (Here’s my article about that beautiful day).

Even if the studio owns lots of real hardware the production asked to rent some Neve 1073 modules (plus some 1176 and Pultec’s). I remember the feeling of seeing Joe breaking all the common gain staging rules and pushing all the equipment damn hard. Boy, what a sound. The drums sound did not change very much from what i heard in the control room to the mastered tracks, and this was achieved with (first of all decades of experience at the highest levels) very basic channel list, common mic placement techniques, quality microphones and a row of 1073 screaming the hell out.

While dreaming my real 1073, i fired up some clones (courtesy of Music Delivery) and performed deep tests over some of the most popular on the mid-budget market, with the idea, for each clone, to mark a checklist of what i believe is responsible for that unique sound.

1) Input transformer

2) LO1166 output transformer

3) BC184 transistors

4) Tantalum/Polystyrene capacitors

5) 2N3055 output transistor

6) 3 gain stages

GEAR UNDER TEST

Heritage Audio HA-73X2 ELITE | 2 CH (STREET PRICE 1290 eur)

80dB, 3 stage fully discrete class A mic preamp

Line input on separate XLR

PAD / LO-Z / 80 Hz HI

Fully discrete class A

JFET based D.I.

External universal power supply for worldwide use

Stam Audio 1073MPA | 2CH (STREET PRICE 790 EUR)

Carnhill input and output transformers

Optional Sowter output transformer

Polystyrene/Vishay-BC capacitors

2N3055 output transistor. 80 dB gain

Completely discrete signal path

Impedance selection (300 – 1200 ohms)

Insert Jack

Warm Audio WA73-EQ | 1CH (STREET PRICE 880 EUR)

Discrete Class A circuit

Carnhill transformers

80 dB gain

PAD / LO-Z / Variable Hi-pass

LED meter

48V Phantom power

Integrated 115/230 V power supply unit

GAP Pre 73 | 1CH (STREET PRICE 450 EUR)

80 dB gain/ air eq / Hi-Pass / Lo-Z

4-step LED output level meter.

Output level control

Line Input / Insert jack / Selectable 600 Ohm output termination.

Connector free internal wiring

Carnhill input and line output transformers.

Polystyrene / Tantalum capacitors

LAB TEST:

Frequency response and T.H.D.

Using my analysis software i ran a 20Hz-20KHz sweep into the clones through a quality passive D.I. box, ensuring the microphone inputs sees correct impedance and an average mic level signal (200 ohm, 50mV).

2 different gain settings were chosen, 30dB and 60dB, adjusting output trimmers for circa -12 dBFS input level into an RME Fireface 800 soundcard. This is how i’d use a 1073 in a real world scenario, the input levels would represent a singer’s voice captured by a large diaphragm condenser microphone or a snare drum on a padded pencil condenser microphone, and the 2 different gain settings would be choosing to record it either the clean or super-dirty way.
Differences are subtle, but devil’s in the details. Mid-band frequency response results in both 30 and 60 dB gain settings are (apparently) very similar for all the preamps, but the T.H.D. figures and behavior at the edges of audio band clearly define what’s happening, double confirmed with later audio listening tests.

30 dB gain setting:

In the low band Stam Audio exhibits 1-2 dB more low-end with a bell around 50 Hz, being the other 3 flatter and very similar, and in the upper-high band Stam Audio and Heritage have a gentle 20 Khz 6db/oct high cut, while Warm Audio remains flatter and Golden Age has a small boost bell around 14Khz.

Looking at the T.H.D. i see very similar values for all 4 devices, having all the same 3rd harmonic figure and a slightly difference on 2nd harmonics, being Stam Audio the most coloured and Heritage the most neutral.

60 dB gain setting:

On a heavy distortion setting, the differences talks about how the electronics is working in extreme conditions, sorting out critical design pro’s and con’s. Here’s how those units sound when pushed hard, and the results will be too confirmed after the real world recording tests.

Heritage confirms to be the more neutral among the four and Stam the most coloured, having more harmonic distortion percentage.

A curious sudden 2nd harmonic drop from 2KHz of the Stam 1073MPA delivers a more gentle and less harsh sound when distorting in the hi band. I don’t know if this tailored behaviour was desired or just a lucky combination of design and components, but in the end i liked it very much. Generally speaking, on high saturation levels the TDH in the mid-bass frequencies is perceived more pleasantly than on the mid-highs, where the sound can become easily gritty and unpleasant to human ears. Filtering some highs (feedback) before the last gain stage helps the overall sound to become less annoying are more enjoyable. (It’s a feature i put intentionally in my UNO tube saturator) and that can be found on other hardware saturators like The Culture Vulture from Thermionic culture or Elysia Character (here as a continuous tone control).

FEATURES CHECKLIST

The following table contains what i believe are the key features of a 1073 design (which itself is omitted in the list), and aside from a pure technical analysis it reveals some coincidences with the test graphs results:

Warm Audio and Golden Age share identical features (and graphs too), while Heritage is one extreme and Stam the opposite, having less key features in common.

The fuller low end in Stam 1073MPA could be an effect of higher inductances of their Sowter output transformer (it is sold either with Carnhill or Sowter output transformer, i have the Sowter version), and the use of high quality film capacitors in the signal path could be responsible for the lower T.H.D. at highest levels and frequencies. On the other hand the more natural sound of Heritage Audio HA-73X2 could be the result of less original 1073 features than others. It is also an industrial SMD build, while their double priced DMA-73 version stays discrete and classic through holes style.

CONCLUSIONS

This review is not intended to give a winner between the four.

All the 1073 clones, in (boring) low gain operation, vaguely have a similar sound. When pushed hard they have different behaviour, and clear differences can be heard. This is confirmed by the different circuit design, critical components choice and cost/benefit compromises.

Ask friends or distributors a demo unit before buying by hearsay. Play, test, record, listen back. Hopefully this article will help people to choose their next microphone preamplifier with some more knowledge.

GALLERY

Microphones shootout. Road to Neumann U47

Thinking about the uniqueness of the Neumann U47, memorable sports performances, legendary tracks by musicians in their prime, and inventive minds that changed the world come to mind.

Why not make peace with the unicity of a moment, a performance, or an athletic feat? Why not draw inspiration from exceptional singularity to move forward and do better, rather than being tied to it with rogue nostalgia and lamenting not having lived in the right place at the right time?

The U47 is a unique microphone, designed to cope with what post-war Germany offered, namely a crumbling, non-centralized electrical grid, sometimes distributed in AC and sometimes in DC. It houses a purpose-built vacuum tube, the VF14, to power filaments at 55V but intentionally underpowered at 35V, fed directly from the only available power rail (105V at 40mA) through a resistor that dissipates about 3 watts and heats up like a crematorium oven (which is why it's often seen mounted upside down to prevent all this heat from damaging the PVC diaphragm, never used again since then).

No sane and normally functioning engineer would ever do something like this, and indeed, it's a case of making the best of a bad situation, technical flair, and a bit of luck here and there. None of the German designers sat down and said, "Now I'll build the best microphone in history." They made a microphone with what they had, produced about 6000 units, and then good night—VF14 gone, post-war era over, enter the U67, another unbeatable gem from Neumann, this time not due to the singular circumstances that led to its conception but for the technical boldness of its design.

Nevertheless, there are around thirty models on the market, from clumsy attempts to exquisite pieces. Since the hype keeps growing, I decided to compare those that come into my lab with my all-original 1960 Neumann U47. Above all, I aim to understand where and why there's always a missing piece to reach the real deal.

Today, I write about the two new contenders on the market, the Warm Audio WA-47 Tube and the Golden Age GA-47, which I carefully measured and listened to in the lab alongside Simone Coen (Chocolate Audio) and Valerio di Lella (Music Delivery). We'll compare what the manufacturers tell us with what we actually observed and heard, trying to convey our impressions.

Let's start with the listening test on vocals, with the usual mic placement as coincident as possible and the singer as centered as possible. Two takes, one soft and one with high vocal emission.

On a low-vocal-emission singing, the two microphones are almost comparable. The preference leans slightly towards the Golden Age for greater harmonic complexity and a better signal-to-noise ratio, a specification that becomes crucial on low-intensity sources. With a more powerful singing, the differences become more pronounced, and in our opinion, more in favor of the Golden Age. It tends to behave more faithfully to the original, responding to high pressures with a decent amount of harmonics that make it 'gritty' as we like it.

Between the two, the WA-47 is clearer. The Golden Age has a softer sound, more distant from the original 47 but perhaps more 'general purpose.

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These impressions are confirmed by the analysis of the frequency response, considering a full-band audio sweep at 1 meter from the source. Both clones fall short where the U47 excels, in that unique emphasis on the frequency range between 5kHz and 10kHz, which can sometimes be excessive (the U47 is NOT a general-purpose microphone). Another confirmation from the sweep responses is the additional brightness of the Warm Audio compared to the Golden Age, which lacks up to 5-6 dB in that spectrum compared to the original Neumann. Below 3 kHz, however, the three microphones are almost identical, at least in terms of frequency response.

The third analysis we conduct, subtle but crucial, is the harmonic distortion of the amplifier. The devil is in the details, and it is precisely on the harmonics that both microphones must make room for this unique and fortuitous combination of design and components that makes the U47 inimitable. The harmonic richness of the K47-VF14-BV8 combo is not replicated, not even close. Peace and goodwill.

As an incurable geek, I couldn't refrain from the technical analysis of components, assembly, and materials, and here's what I found:

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Warm Audio WA-47 Tube:

Chassis: Aluminum and power supply typical of overseas OEM’s.

Capsule: 47-style biased at 80V (an expedient that simplifies the circuit arrangement but alters the capsule's response, typically biased at 55-60 volts).

Tube: Current production JJ 5751 (a near equivalent to 12AT7), a dual triode with a slightly bright timbre.

Transformer: Custom AMI.

Components: Rather cheap, except for an output Solen capacitor.

Assembly: Industrial, PCB without solder mask (the traces will eventually oxidize).

Price: EUR 1059.

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Golden Age GA 47:

Chassis: Brass and iron basket, both crafted very well.

PSU: Original design.

Capsule: Style 67 (likely from Oktava), biased at 60V.

Tube: Telefunken EF800 connected as a triode.

Transformer: Dual-coil, unbranded.

Components: Quality.

Assembly: Handcrafted, somewhat naif wiring.

Price: EUR 1514.

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Are they beautiful microphones? Yes. Do they sound good? Yes. Do they sound like the Neumann U47? No.

Between the two, I appreciate the Golden Age more for several reasons, perhaps foremost because the brand's communication revolves around a new U47-inspired condenser microphone, while Warm Audio claims not to hear the difference between its young offspring and the old grumbler. We heard it, and how.

The clones, replicas, wannabes, pretenders—pick the synonym you prefer because any attempt to reproduce that unique peculiarity will be in vain. Not because there aren't skilled designers, but because that idea made sense in that context. It's the product of needs and circumstances that are now unrepeatable, and it's right for it to stay there, in the Olympus of singularities, alongside John Lennon's "Imagine" and René Higuita's scorpion kick in '95.