TELEFUNKEN TF51 Stereo Set

Product overview

The TELEFUNKEN TF51 Stereo Set is a frequency and gain matched pair of TF51 large-diaphragm tube condenser microphones from TELEFUNKEN Elektroakustik's Alchemy Series, with a dual power supply that runs both microphones and an FC03S locking flight case.

Each TF51 delivers a fresh take on the classic "Austrian" tube sound: a smooth midrange, a balanced low end and an airy, open top end. All critical components, including the capsules, tubes and transformers, are hand-selected and tested for matched gain and frequency response, so both microphones give identical responses for the most critical stereo recording. The American-made M 901S powers both microphones at one time, and the whole system travels in one case.

Maximum SPL (1% THD)	128 dB SPL
Self‑noise	8 dBA
Sensitivity	19 mV/Pa
Frequency and gain matched	2 x TF51

Key features

• Two frequency and gain matched TF51 microphones for identical left and right channels
• Capsules, tubes and transformers hand-selected and tested for matched gain and frequency response
• TK51 edge-terminated capsule and TELEFUNKEN Elektroakustik 6072A vacuum tube in each microphone
• Cardioid, omnidirectional and figure-8 on both microphones
• 128 dB SPL maximum level and 8 dBA self-noise per microphone
• M 901S dual power supply runs both microphones at one time, with two 9-position pattern switches
• FC03S locking flight case with dual combination locks holds the complete stereo system
• Designed and hand assembled in the USA

Sound character

The TF51 carries forward the "Austrian" microphone sound that TELEFUNKEN is closely associated with. Its smooth midrange and airy top end bring out detail and space, while a balanced low end keeps the sound natural. TELEFUNKEN describes the result as open, smooth and lifelike, a character that suits stereo pictures of acoustic instruments, strings, piano and drum overheads.

Capsule, tube and transformer

Each TF51 is built around the TK51 edge-terminated large-diaphragm capsule, a TELEFUNKEN Elektroakustik 6072A vacuum tube that is tested, burned in and screened by TELEFUNKEN, and a custom German-made output transformer (T31). Each microphone delivers 8 dBA self-noise, 86 dBA signal-to-noise ratio and 128 dB SPL maximum level.

Matched for stereo

All the electronic components in each pair are matched sonically and electronically, including the capsules, transformers and vacuum tubes. Both microphones are tested for matched gain and frequency response, giving you the confidence that the left and right channels will respond identically in coincident, near-coincident and spaced stereo techniques.

Dual power supply and patterns

The M 901S is hand built in South Windsor, Connecticut, and is capable of powering both microphones at one time. It features a slow-ramping filament voltage to extend tube life and full regulation, so the microphones always operate the same regardless of line voltage variations or location; full regulation also means it can safely power only one microphone if needed. Each power supply is calibrated to the microphone system it comes with and is burned in as a full unit. The M 901S dual power supply has two 9-position polar pattern switches, one per microphone, giving nine patterns from omnidirectional to figure-8, including cardioid. Each microphone's pattern is set independently, which makes mid-side and Blumlein recording simple.

FC03S locking flight case

The FC03S is a combination locking flight case with a shell made from a blend of hardwoods, wrapped in a premium travel fabric, with dual combination locks and nickel trim. It holds two microphones, one stereo power supply, two tube microphone cables and two shock mounts, with zipper compartments for cables in the lid, so the complete stereo system travels in one case.

Recommended applications

TELEFUNKEN recommends the TF51 for vocals, acoustic guitar, violin, drum overheads, grand piano, mandolin and percussion. As a matched pair, it is ready for the stereo side of that list: drum overheads and room, piano, acoustic guitar, strings, choirs and ensembles, and any source where a stable, detailed stereo image matters.

Designed and hand assembled in the USA

The Alchemy Series is designed, hand built and tested in Connecticut, USA, in the same facility as TELEFUNKEN's Diamond Series, by a small, dedicated team of engineers and technicians. Each microphone is individually tested and listened to, with hand-plugged circuit boards, which keeps tolerances extremely tight from one microphone to the next.

What's in the set

This product is the TF51 Stereo Set: two matched TF51 microphones that share one M 901S dual power supply, with two cables, two shock mounts, two stand mounts and two sleeves, all in one FC03S locking flight case.

In the box

• 2 x TELEFUNKEN TF51 microphones, frequency and gain matched
• M 901S dual tube microphone power supply with two 9-position pattern switches
• Mains power cable for the power supply
• 2 x M 803 tube microphone cables, 7 m (7-pin XLR)
• 2 x M 703 elastic shock mounts
• 2 x M 782 stand mounts
• 2 x MS01 microphone sleeves
• FC03S locking flight case

TELEFUNKEN Elektroakustik warranty: 90 days on the capsule and tube and one year parts and labour on the amplifier and power supply. Register the microphones at TELEFUNKEN to extend this to one year on the capsule and tube and four years on the amplifier and power supply. Alchemy Series warranties are fully transferable between owners.

TELEFUNKEN TF51 Stereo Set: frequently asked questions

What is the difference between a Stereo Set and a Matched Pair?

Both contain two frequency and gain matched microphones, two tube microphone cables, two shock mounts and two stand mounts. The Stereo Set adds a dual power supply that runs both microphones and one locking hard-shell case; a Matched Pair has two separate power supplies and two zipper cases.

Does the set need phantom power?

No. Both microphones are powered by the included M 901S dual power supply. Connect the power supply to your preamp with standard 3-pin XLR microphone cables.

Can each microphone use a different pattern?

Yes. The M 901S has two 9-position pattern switches, one for each microphone, from omnidirectional to figure-8, so mid-side and other mixed-pattern setups are easy.

How long should the system warm up?

TELEFUNKEN recommends letting the system warm up for 10 minutes after switching on the power supply.

Is a TF51 Matched Pair available?

Yes, the TELEFUNKEN TF51 Matched Pair is listed as a separate product at Shivansh Electronics.

Where can I buy the TELEFUNKEN TF51 Stereo Set in India?

The TELEFUNKEN TF51 Stereo Set is available from Shivansh Electronics, Kolkata, West Bengal, India, with delivery across India.

Workflow 1: Blumlein figure-8 pair

A natural, enveloping stereo image of an ensemble in a good-sounding room.

Connections

Connect	To
TF51 microphones 1 and 2	The two inputs of the M 901S dual power supply via the two TELEFUNKEN M 803 7‑pin tube microphone cables
M 901S to preamp	Mic preamp / audio interface inputs (standard 3‑pin XLR microphone cables)
M 901S power inlet	Mains power (115V or 230V as set)

Setup

1. Mount both TF51 microphones on a stereo bar, one capsule directly above the other, angled apart left and right.
2. Set both pattern switches on the M 901S to figure-8.
3. Connect both microphones to the M 901S with the M 803 cables, switch on and let the system warm up for 10 minutes.
4. Set identical gain on both preamp channels, pan them left and right, and check the image on headphones and speakers.

Tip: The rear lobes of the figure-8 patterns capture the room, so place the pair where the room sounds good.

Workflow 2: Mid-side (M-S) stereo

Stereo recordings whose width can be adjusted after the session.

Connections

Connect	To
TF51 microphones 1 and 2	The two inputs of the M 901S dual power supply via the two TELEFUNKEN M 803 7‑pin tube microphone cables
M 901S to preamp	Mic preamp / audio interface inputs (standard 3‑pin XLR microphone cables)
M 901S power inlet	Mains power (115V or 230V as set)

Setup

1. Point the first TF51 (mid) at the source and place the second TF51 (side) directly above it, its front facing the side.
2. Set the M 901S pattern switch for the mid microphone to cardioid and the switch for the side microphone to figure-8.
3. Connect both microphones to the M 901S with the M 803 cables, switch on and let the system warm up for 10 minutes.
4. Record both channels, then decode the mid and side signals to left and right in your mixer and set the width by ear.

Workflow 3: Drum overheads

Recording the whole kit from above as a balanced stereo picture.

Connections

Connect	To
TF51 microphones 1 and 2	The two inputs of the M 901S dual power supply via the two TELEFUNKEN M 803 7‑pin tube microphone cables
M 901S to preamp	Mic preamp / audio interface inputs (standard 3‑pin XLR microphone cables)
M 901S power inlet	Mains power (115V or 230V as set)

Setup

1. Place the two TF51 microphones above the kit on boom stands as an XY or spaced pair, fronts facing down towards the drums.
2. Set both pattern switches on the M 901S to cardioid.
3. Connect both microphones to the M 901S with the M 803 cables, switch on and let the system warm up for 10 minutes.
4. Set identical gain on both preamp channels, pan them left and right, and check the image on headphones and speakers.

Tip: Keep both microphones the same distance from the snare so the centre of the kit stays focused.

Workflow 4: Piano in stereo

Grand piano with a full, even spread from bass to treble.

Connections

Connect	To
TF51 microphones 1 and 2	The two inputs of the M 901S dual power supply via the two TELEFUNKEN M 803 7‑pin tube microphone cables
M 901S to preamp	Mic preamp / audio interface inputs (standard 3‑pin XLR microphone cables)
M 901S power inlet	Mains power (115V or 230V as set)

Setup

1. Position the two TF51 microphones over the strings, one towards the bass and one towards the treble.
2. Choose cardioid on both for a close, focused sound or omnidirectional on both for a more open sound with the room.
3. Connect both microphones to the M 901S with the M 803 cables, switch on and let the system warm up for 10 minutes.
4. Set identical gain on both preamp channels, pan them left and right, and check the image on headphones and speakers.

Workflow 5: Choir, ensemble and room with spaced omnis

Choirs, string groups and rooms recorded with width, depth and a full low end.

Connections

Connect	To
TF51 microphones 1 and 2	The two inputs of the M 901S dual power supply via the two TELEFUNKEN M 803 7‑pin tube microphone cables
M 901S to preamp	Mic preamp / audio interface inputs (standard 3‑pin XLR microphone cables)
M 901S power inlet	Mains power (115V or 230V as set)

Setup

1. Set the two TF51 microphones on tall stands in front of the group, spaced apart.
2. Set both pattern switches on the M 901S to omnidirectional.
3. Connect both microphones to the M 901S with the M 803 cables, switch on and let the system warm up for 10 minutes.
4. Set identical gain on both preamp channels, pan them left and right, and check the image on headphones and speakers.

Tip: Listen in mono as well as stereo and adjust the spacing until both sound natural.

Workflow 6: Acoustic guitar in stereo

Singer-songwriters and session players recording acoustic guitar with width.

Connections

Connect	To
TF51 microphones 1 and 2	The two inputs of the M 901S dual power supply via the two TELEFUNKEN M 803 7‑pin tube microphone cables
M 901S to preamp	Mic preamp / audio interface inputs (standard 3‑pin XLR microphone cables)
M 901S power inlet	Mains power (115V or 230V as set)

Setup

1. Place one TF51 towards the neck and the other towards the body of the guitar, both facing the instrument.
2. Set both pattern switches on the M 901S to cardioid.
3. Connect both microphones to the M 901S with the M 803 cables, switch on and let the system warm up for 10 minutes.
4. Set identical gain on both preamp channels, pan them left and right, and check the image on headphones and speakers.