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The R-F-T line evolves into an enchanting series of microphones with new bodies, enhancements, and accoutrements

Review by Paul Vnuk Jr.

Twenty years ago, Telefunken Elektroakustik opened its doors in South Windsor, CT, and returned the Telefunken ELA M 251 to production after almost forty years. This gave birth to the Diamond Series of ultra-high end classic recreations including the C12 and U47.

The R-F-T line was launched in 2005, combining global sourcing and US assembly/testing, bringing Telefunken sound and quality to a budget-conscious price point. Over a decade, the line would grow to include the AR-51, AK-47 MKII, and the CU-29. The first two mics pay apparent homage to classic mics of the past, while the CU-29 or Copperhead introduced a brand new Telefunken design.

Now the R-F-T line becomes the Alchemy Series. While the names and models are similar, the Alchemy series is not merely the R-F-T line with a new look and packaging; each model is complete re-boot.

The Alchemy Quartet

The Alchemy series comprises four models: The TF47, TF51, TF29, and TF39. Each one shares a direct lineage to a past R-F-T incarnation, and in some cases, a famous classic Diamond Series cousin.

Except for the cardioid-only TF29, each mic is a multipattern tube microphone. Alchemy microphones share the same brass body, head basket, and 7.87″ x 1.81″ profile.

The new grille

The new grille is a single-construction steel frame with two layers of mesh; the R-F-T was three layers. The opening is also slightly longer than the R-F-T series for a better capsule position. According to Telefunken, “These changes provide a more open and transparent response. For reference, the 251 headgrille has two layers of mesh.”

The guts

While each mic looks alike and shares the same ‘digs’, each one boasts a different capsule, tube, and transformer. Similar in each mic is the use of UK-made polystyrene film filter caps, a Sprague output cap, and a Nichicon Fine Gold cathode cap.

The System

The newly designed kits are quite impressive. They include two mounting options: a hard ring mount, and an open-faced shock mount. There’s also a microphone dust cover, a high-flex 7-meter cable, and a US-assembled power supply. The microphone and accessories live in a compact hard nylon carry case measuring 10.5 x 13 x 5.5″. This is one of the nicest mic cases I’ve seen in a while. It’s much better than the usual off-the-shelf aluminum briefcases that come with most microphones in this price range. It’s more robust, and designed to fit the components comfortably with no cramming or overstuffing.

For this review, we’ll be focusing on the TF47 and TF51. We’ll look at the two Copperhead models in a future issue.

Telefunken TF47

Telefunken Alchemy TF47The TF47 is the U47-flavored model in the line and a direct descendant of the R-F-T AK47 MKII, which we reviewed back in October 2011. The TF47 is not intended to be a U47 clone; rather, it’s a modern design that falls into the U47 family of sound.

The TF47 uses an all-brass K47-style center terminated capsule. This marks a significant change from the previous AK-47 MKII, which used a K67-style capsule. Telefunken mentions that the new K47-style capsule is “…just as punchy in the mids, but the high end is smoother and a bit less ‘in your face’ with a fuller low end.”

The tube in the TF47 is a NOS American-made Raytheon/Philips 5840W. This tube was used in the AK-47 MkII and is also used in the ELA M 260. The transformer is also carried over from the AK47 MKII and is a custom-wound, historic spec BV8, which was used in classic U47 microphones.


Sonically, the TF47 is flat from 20Hz up to 500Hz, where it starts rising to a 4kHz peak of about 3dB. From there, the curve rolls off quickly. As such, the TF47 does exhibit the telltale midrange thrust one expects in a 47-family microphone; it’s a sound that will quickly push a vocal, guitar or drum front and center in a mix.

I’ll get more into use below, but one aspect of the TF47 that I quite enjoy is how clean and smooth it is. While it offers the classic U47 thrust and tonality, it doesn’t sound rough, dusty, or vintage in any way.

Frequency Range: 20Hz – 20kHz

Sensitivity: 22 mV/Pa

THD at 1kHz at 1Pa (Amplifier): < 0.3%

Output Impedance: < 300 ohm

Maximum SPL (for 1% THD): 125dB

S/N Ratio: 84 dBA

Self Noise (Amplifier): 10 dBA

Telefunken Alchemy TF51Telefunken TF51

This is my third time reviewing this microphone. We first looked at the R-F-T AR-51 in November 2010, when it was based around a TK67 capsule. Version two was reviewed in May 2014, after Telefunken changed the capsule to an edge-terminated CK12 style (closer to the ELA M 251 design). I described the original AR-51 to have a feathery top end, and the 2014 capsule update added smoothness and a fuller low end capture. The TF51 retains the same capsule, and thanks to the new dual-layer mesh grille, inches even closer to the 251 sound. On that theme, the TF51 uses the same Telefunken-branded 6072A miniature tube used in the Telefunken ELA M 251E and C12.

The transformer in the TF51 is custom designed and made in Germany by Haufe, which also manufactures the T14/1 transformer found in the 251E and C12. It boasts improved low end frequency response and lower THD figures than its predecessor, due to a better impedance match to the 6072A.


Like the TF47, the TF51 is fairly neutral from 20Hz to 200Hz, but with just a touch more body. Its midrange response is gently scooped by less than 1dB, and then it displays a 1dB rise at 3kHz that falls back to zero at 6.5kHz, followed by a 2.5dB peak at 10kHz.

Again, I would describe this mic as exhibiting a clear yet feathery top end, a smooth and neutral midsection, and a low end that’s full and deep but not exaggerated.

Frequency Range: 20Hz – 20kHz

Sensitivity: 19 mV/Pa

THD at 1kHz at 1Pa (Amplifier): < 0.4%

Output Impedance: < 300 ohm

Maximum SPL (for 1% THD): 128dB

S/N Ratio: 86 dBA

Self Noise (Amplifier): 8 dBA

In use

I started with some side-by-side comparisons of the entire Alchemy family. I tracked a song with all of the mics in a close capsule star pattern on a full song of small-body Gibson acoustic guitar, female vocals, shakers, and percussion. When switching between mixes made with each mic, it was like turning a focus or tone knob. The TF51 was smooth and very neutral, with excellent clarity and depth. Selecting the TF47 tightened up the lows while thrusting the upper bite of the acoustic and the vocals forward. Switching to the TF39… stay tuned for a future review of my results!


The AR-51 has long been one of my favorite drum overhead microphones, especially when you want the overheads to represent the sound of the whole kit with individual spot mics mixed in at low levels for clarity and punch. While I only had a single TF51, it continued to shine in this use. If you like to do Glyn Johns-style drum miking, I can’t recommend a pair of TF51 mics enough.

On drums, the TF47 is better suited to front of kick, or as a mono room mic, where it takes compression quite well.


On guitars, it depends where you want the instrument to sit in the mix and what you’re trying to capture. If you want a more rock ‘n’ roll acoustic sound to poke out of a dense mix, I would choose the TF47, but if acoustic guitar is the star of the mix, then the TF51 captures the rich lows and strums nicely.

On electric guitar, 90% of the time I would choose the TF47 for its thrust and controlled low end, but on bass cabinets, I’ve always been a fan of the TF51 which, similar to acoustic guitar, lets the full, deep low end through while highlighting the detail of the fingers or pick on the strings.


Here again, it’s a tossup. On female vocals in a sparse folk mix, I preferred the full, feathery TF51, but on a fuller indy rock track with loud guitars and a male vocalist, the TF47 was the better choice.


Telefunken has taken its popular R-F-T line and made some well-executed improvements in the Alchemy Series. Despite their sharing of bodies and packaging, these are not simply variations on a single mic design. I’m pleased that they’re quite different from one another, and they really do hit their familial targets quite well. If you’re after a modern take on one of the classic mic styles without spending boutique dollars, then these might be the mics for you.

Price: TF51 $1,895, TF47 $1,895

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