Aztec • Boutique Tube Microphone

Overview

The Roswell Aztec is a boutique multipattern tube microphone built without compromise.

The Aztec results from several years' worth of R&D, capsule design, and component testing, during which every piece of the microphone and power supply was reviewed, revised, and improved. The result is a stunning microphone: intimate and rich, never harsh or brittle.

Testimonial

I’m a microphone maniac. Most clones don’t do anything for me.
The Roswell Aztec made my jaw drop. It has this modern pop-edge that differentiates an Elam 251 from a C12, without the annoying harshness of most modern microphones that strive to achieve this.

Christian Seitz
Producer (58M records sold)

Holy ****, this mic sounds great!

Lij Shaw
Toy Box Studio, Nashville
RS Rockstars podcast

It's not a clone... it's better

The Aztec does not pretend to be a copy of anyone else's microphone. We borrow liberally from proven designs, and we relentlessly upgrade everything we possibly can.

The Aztec uses a single triode circuit topology, with a selected 6072 tube. Noise filtering components within the mic are upgraded, using higher quality and higher value parts to reduce noise. Input and output capacitors, which pass the mic's audio signal, are ultra-premium parts selected by ear.

The original European power supplies were typically unregulated, which means tube voltage will drift as the mains AC voltage changes. Rather than subject your recordings to unexpected sonic changes just because the HVAC or refrigerator cycles on or off, we provide a fully regulated power supply that delivers precisely the correct filament and plate voltages, regardless of mains AC changes.

Review Excerpt

I tried Aztec alongside some mics that I had on hand ranging from $5000–$7000, and it absolutely held its own in sonics and depth -- and I do not say that lightly.

Paul Vnuk
Editor, Recording Magazine (see full review here)

Versatility, by design

The Aztec provides nine discrete polar patterns, each of which can be precisely recalled via the rotary potentiometer on the power supply.

A switch on the microphone engages a 10dB attenuation control, which allows the mic to be used for louder sources without internal clipping.

A second switch on the mic engages a high-pass filter, which rolls off the mic's low frequencies (-3dB @ 140 Hz); use this to control proximity effect with close mic placements.

Testimonial

This mic could pass for a $5000 model ... the attention to ALL the details is astounding.

Rob Tavaglione
Writer, MIX Magazine
Catalyst Recording

Included

• Roswell Aztec microphone (hand-built in California)
• Roswell Aztec power supply (hand-built in California)
• Gotham GAC7/Neutrik cable
• AudioQuest IEC power cord (available for IEC type B, E, and G plugs for US/CA/JP, UK, and much of the EU)
• Shockmount
• Flight case

Cosmetic Options

Two options are available for the Aztec microphone body: satin black or "Vintage Cream." The cream color is a powdercoat process; because powdercoating is essentially an industrial process, some minor imperfections are inevitable. The finish is nearly indestructible though. 

The power supply for black microphones is powdercoated in a durable, textured black finish. "Vintage Cream" microphones including a matching-color power supply, while supplies last; after current inventory is gone, VC mics will also have textured black power supplies.

If you prefer the grille to be black chrome, we can make that substitution at no cost.

High-Pass Filter Options

The high-pass filter was designed to be audible: -3dB @ 125 Hz. If you prefer a higher or lower frequency, contact us. We can easily make this change. 

Tube Options

Because there are practically no suitable NOS 6072 tubes remaining on the market, the Aztec uses a specially selected modern production 6072. Every tube is tested for noise, frequency response, distortion, and microphonics. 

The vast majority (95+%) of NOS 6072 tubes we've tested have lower gain, higher noise, microphonics, and/or frequency response anomalies, compared to our standard Aztec tube. The very few NOS tubes that pass our strict QC are available at higher cost; see the menu options above.

Features & Benefits

• Our RK-251 capsule, single-triode circuit, and custom European-made transformer capture a timeless sound: full low end, honest midrange, and airy, intimate highs.
• Independent pad and filter switches, and polar pattern control provide comprehensive versatility.
• The 9-position pattern control, located on the power supply, provides repeatable, discrete selection of polar pattern.
• Both the Aztec microphone and its power supply incorporate premium, rare, and "unobtanium" components. These parts elevate the mic's sound, drawing comparisons to well-preserved, revered vintage microphones.
• The included Gotham GAC7/Neutrik XLR cable ensures maximum signal fidelity and minimum voltage loss. The included AudioQuest IEC power cord ensures a robust connection to mains AC supplies.
• The Aztec power supply is fully regulated, ensuring consistent sound even when subjected to varying AC supply levels.

Jargon for mic nerds

• The pattern control is a Swiss-made precision potentiometer, which we hand-wire (point to point) using 1% tolerance, audio-grade resistors.
• The input capacitor was developed decades ago for the aerospace industry; it is a high-voltage part designed to be extraordinarily stable and reliable even when subjected to extreme temperatures and forces (and as such is arguably over-spec'd for use in a microphone -- although we love it for its transparent sound).
• The mic's output transformer is hand-wound specifically for this microphone in Europe, using high-purity copper wire.
• The Aztec power supply is fully regulated, both plate and filament, to ensure rock-solid power rails for the tube, capsule, and circuitry. Each one is manually adjusted at our shop to 0.1VDC tolerance.
• The B+ supply runs at a higher voltage than standard; we have optimized the circuit for this.
• The included XLR7 cable uses genuine Gotham GAC7 and Neutrik connectors. We hand-terminate these in-house, then "burn in" each cable on a proprietary conditioning rig for 72 hours. The heavier conductors in the GAC7 are used for the tube heater circuit, to minimize cable losses.
• The lid of the power supply is vented to reduce component heat exposure. Power resistors are over-spec'd to ensure long life. Regulators have oversized heat sinks. The circuit board is vented to enable convection cooling of any component that consumes more than 0.1W.
• All electrolytic capacitors (microphone and PSU) are selected audio grade parts. Most are our own proprietary recipe, Roswell branded parts.
• Internal wiring in the PSU is Kimber brand OFC, solid core, with Teflon insulation; it's difficult to use, but is the best-sounding wire we've ever tested.

See the PSU internals below. This image shows some of our custom electrolytic filter capacitors, vintage Japanese audiophile resistors, bridge rectifier boards (mounted vertically to aid in convection cooling) with NOS Telefunken diodes, gold-plated German-made fuse and socket, oversized heat sinks on the regulators, etc.