Two Venerable Classic Tube Condensers in One Modern Mic
The legendary “47” and “48” tube condenser microphones of the late 1940s and 1950s have defined the sound of countless iconic recordings and demand for vintage models is high. But securing a 70-year-old mic in good working condition is a tedious and expensive proposition. Now, Sweetwater is excited to present the United Studio Technologies Twin 48, which combines these two venerable designs in one modern, performance- and value-packed large-diaphragm tube condenser mic.
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Twin-mode operation
The UT Twin 48’s two operating modes go beyond just polar pattern selection. Vintage 47s and 48s each derived their cardioid polar patterns using different methodologies, which gave these two coveted classics subtle tonal differences and slightly different pickup patterns. The UT Twin 48 delivers both options in a single microphone. The Twin 48’s 47 mode offers both 47 cardioid and omnidirectional patterns; the 48 mode offers 48 cardioid and figure-8. Each cardioid mode yields a different tonal flavor and performance.
Unparalleled versatility
In 47 Cardioid mode, the rear diaphragm is de-coupled using a process called True Cardioid. This allows for greater volume, higher sensitivity, and enhanced ambience and top-end detail. In contrast, 48 Cardioid mode employs Active Cardioid, which applies the same voltage to the rear diaphragm as is used on the back plate. This results in a warmer, more intimate, and tightly focused sound with somewhat lower sensitivity. While each mode has its adherents among golden-eared engineers, the versatile options offered by the Twin 48 make it a must-have for inclusion in any studio’s mic locker. Experiment to capture a vocalist in the most flattering way, add tasty ambience to a horn part, and capture strings with stunning clarity and articulation — all with a single microphone!
Astute engineering for huge tube sound
Specifying the right vacuum tube is critical to the design of any valve mic. As original 47s and 48s are treasured for their huge sound, United Studio Technologies based the Twin 48’s amplifier stage around a select new-old-stock EF86 pentode — a descendent of the tube used in the originals. This results in a massive, bold, and rich sound, thanks to the pentode’s harmonic profile, which is quite different from that of modern dual-triode tubes. Assisting in the Twin 48’s sonic largess is its historically correct, custom-made, single-backplate/dual-diaphragm K48 capsule, which helps capture sources and render them with a creamy-smooth, vintage-flavored sound, taming overly bright or sibilant sources more competently than many vintage-style mics.
Top-drawer components throughout
United lavished the Twin 48 with top-drawer and custom-made components, including audiophile-quality polystyrene, tantalum, and film capacitors, PRP thin-film resistors, and a custom replica transformer. Designed to the meticulous measurements made from a mint specimen of the original German transformer, the Twin 48’s US-made UT-BV8 transformer is custom wound to the original Braunbuch specifications and set to the same laminations used on the historical parts. United used all high-nickel alloy laminations and employed a copper Faraday shield for reduced RFI (radio frequency interference). To ensure flawless communication between the mic and its power supply, United Studio Technologies included an ultra-premium Octave 7-conductor cable from the German company Sommer, specially configured and optimized for the UT Twin 48.
High-performance power supply
In a tube microphone, anything less than an excellent power supply design will act as a performance bottleneck, so United went all out for the Twin 48 with a fully discrete PSU that features discrete, individually isolated rails, a custom US-made discrete regulator for the filament voltage, and fully discrete Zener diode regulation for the high-voltage rails to ensure clean, calibration-free operation. Custom US-made PRP resistors and high-quality, long-life electrolytic capacitors are deployed throughout, along with a beefy, over-spec’d, frame-mounted linear power supply transformer. The power supply is also fitted with both an inline EMI/RFI AC input filter as well as a selectable RF filter on the audio output, which can be engaged from the front panel.
United Studio Technologies Twin 48 Features:
- Large-diaphragm tube condenser microphone
- 34mm brass, single-backplate K48 capsule
- 6-micron, 24k gold-sputtered Mylar diaphragm
- Vacuum tube: select NOS EF86 pentode
- Frequency response: 20Hz–20kHz
- Max SPL: 137dB @ 0.5% THD
- Polar patterns: 47 cardioid, 48 cardioid, 47 omni, 48 figure-8
- Output impedance: 35 ohms
- Self noise: 11dBA
- Includes power supply, shockmount, and custom vintage-style briefcase
