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Review

2006.01.06

Soundelux E47 Tube Microphone

Pro Audio Review  - by Stephen Murphy

As time marches on, the number of coveted pre-1960s tube microphones available on the open market diminishes. And of the mics that are available for purchase, the chance of picking up a mic that functions at a sonic quality commensurate to its market price is even smaller. While several options exist for expert rebuilding, refurbishing and/or modifying a vintage mic, these choices often come at a steep price.
 The allure of these mics, however, is based in real value - when working to their potential, there is no denying the aural "magic" and often-intangible allure they possess.

 
Product Points
Applications:

Studio, broadcast, live performance recording

Key Features:

 Multipattern tube microphone and matched power supply; 1-inch gold-sputtered diaphragms; fixed cardioid or continuously variable polar patterns; suspension mount and wood case.

REVIEW SETUP

SP Technology Timepiece 2.0 and Westlake LCW 8.1 studio monitors; Bryston SST and Hafler P3000 amplifiers; API 512 mic preamp; Universal Audio LN-1176 compressor; Zaolla Silverline and Kimber cables.


As vintage models disappear, the market for new models meticulously recreated in the image and sound of coveted vintage microphones has steadily grown. Soundelux Microphones continues its advance in this area with the release of the E47 tube microphone modeled after the Neumann-made Telefunken U 47 microphone.

Features

In 1948, Neumann introduced the Telefunken-distributed U 47 microphone - the first condenser with switchable patterns (cardioid/omni). The U 47 utilized the VF14M tube, a metal-clad pentode tube (configured as a triode) along with Neumann's M7 capsule, a 12-micron PVC-based dual-diaphragm assembly with a glued-on membrane tensioning ring.

Over the years, the U 47 mic went through several design modifications, ultimately evolving into the popular U 67 microphone in 1960 when the capsule design switched to Mylar ?lm (instead of PVC) and a screwed-on tensioning ring (instead of glue). The U 67 also added a low-end shelf and amplifier pad.

 The Soundelux E47 is designed to invoke the sonic characteristics of the original while also offering improved performance specifications and additional features not found on the original U 47 - at approximately half the going rate of its period counterpart. These factors plus a three-year warranty and the removal of the increasingly significant "vintage operating condition x-factor" make the E47 an attractive purchase option in craftsman-quality tube microphones.

 The nearly nine-inch long Soundelux E47 housing is based on the original 1948 issue of the U 47, chrome grille and all (in 1956, the U 47 switched to a matte grille and the body was shortened by nearly three-inches thanks to the reduction in size of electronic components, capacitors more specifically). The E47 body sports the instantly familiar dull-gray matte finish found on all larger Neumann mics.

 While the E47 is quite similar to the U 47 in design and operation, several modifications and "improvements," if I may be so bold, were made. One of the most significant modifications to the original design is its fully variable polar pattern capability. A retro-style knob on the E47 power supply smoothly sweeps the mic's directionality from omni (fully counterclockwise) to cardioid (center) to bipolar (fully clockwise).

 The mic can also be locked in cardioid-only mode via a small switch located inside the microphone housing. Changing the position of this switch requires the removal of four screws, sliding the sleeve off the inner-assembly and flipping the tiny switch mounted to the circuit board just above the tube. The subminiature-style tube is soldered directly to a horizontal spring-mounted circuit board.

 E47 designer David Bock declined to print the subminiature tube model used in the Soundelux mic, but explains, "I found a tube with the same plate impedance as the VF14 without having to use a VF14. The plate impedance is the most critical factor in replicating the performance of the original U 47 tube since matching to the output transformer happens at this node." It should be noted that the VF14 went out of production in the early 1970s and is nearly extinct worldwide.

 Cardioid mode specifications according to the manufacturer are an overall frequency response of 20 Hz - 20 kHz; impedance is 200 ohms and load impedance is 1000 ohms; signal-to-noise ratio is 79 dB (A-weighted); self noise is 15 dB (A-weighted); maximum SPL is 134 dB (< 0.5% THD); dynamic range is 119 dB and the maximum output voltage is 5.29 volts.

 The E47 is 2.48 inches in diameter, 8.95 inches long and weighs in at 1.34 pounds. The E47 package includes a suspension mount, separate power supply (with sweepable polar pattern control), and a cherry-lacquered wood case for the mic.

 In Use

 The Soundelux E47 microphone ships in fixed-cardioid mode. In this mode, the mic exhibits a 3 dB improvement in output level due to the reduced capacitance when using a single diaphragm. It is in this mode that, according to Bock, the mic is the most faithful to the U 47 sound.

 The increased proximity effect in this mode accounts for a good part of the faithfulness, as the U 47 was very proximity effect-prone - distance from the source was large factor in the creative use of the U 47. In the cardioid-only mode, Bock and Soundelux pretty much nailed the big, wonderful sound of the U 47, right down to its varying frequency response based on the sound pressure level entering the mic - another frequently noted characteristic of the original.

 Given the reasonably involved procedure to switch the modes, I suspect users will come to predominately choose one mode over the other. I do not know if, as a studio owner, I would want a parade of in-house and independent engineers and assistants constantly tampering with the inside of the mic.

 Being a fan of continuously variable polar pattern microphones, I prefer this mode over the absolute faithful approach. This is an excellent-sounding mic and its creative use is further enhanced through the use of the sweepable pattern control.

 The E47 was a top performer in the vocal category. While the Soundelux mic exhibited an increased top end over the U 47s and other similar vintage microphones (U 67, U48) I have used, it was never excessive or brittle - an increasingly common sound I find in newer, artificially hyped microphones.

 The E47 sounded absolutely great on lower winds - bass clarinet, baritone and tenor sax were some of my favorite uses of this mic. The E47 also proved its worth as a distance mic on brass and string ensembles.

 Between placement techniques and the sweepable patterns, I found I could obtain the sound I was looking for without EQ (save a low shelf). I used practically no EQ on tracks cut with the E47 in mixdown, except when other instruments in the mix demanded space.

 Summary

 While certainly "up there" in price, the importance of having a few craftsman-quality mics like the Soundelux E47 in the locker cannot be over emphasized. It is one of those non-secrets in audio recording that seems to be continuously forgotten, to the point of becoming secret again.

 Soundelux once again shows a craftsman-quality design and build in the E47 tube microphone. And again, when faced with the gamble of picking up a vintage model with uncertain performance and potentially imminent maintenance needs for twice the cost, I would opt at this point for the E47 - one of the most creatively variable microphones I have ever used.

 Stephen Murphy, contributing studio editor for PAR, has recorded hundreds of vinyl and CD releases, including a Grammy Award-winning and a Platinum-selling album. Steve can be reached at editor@smurphco.com.