Neumann M147 Cardioid Tube Condenser Microphone Operating Instructions

Neumann M147 Cardioid Tube Condenser Microphone

Description

The M 147 Tube is a large diaphragm studio condenser microphone with a capsule with a cardioid polar pattern. The input stage is a vacuum tube (valve) with sound properties unique to this type of device. The M 147 Tube is characterized by

• very low inherent self-noise and a wide dynamic range
• a newly developed circuit design with a vacuum tube input stage and a transformerless output stage
• the full, rich and warm sound of a tube microphone.

The microphone has a balanced transformerless output and is powered by the included N 149 A power supply unit. The front of the microphone is designated by the Neumann logo.

The M 147 Tube Condenser Microphone

The M 147 Tube is a transformerless tube microphone. It is equipped with the legendary dual-diaphragm capsule made famous in the U 47 and M 49 microphones (“M 7 capsule”). It is, like its predecessors, especially suited to speech and vocal recording. This is not only due to its capsule design but also because of the extremely low inherent self-noise level. A vacuum tube is used as the input stage of the M 147 Tube. Unlike earlier tube microphones which needed a transformer-coupled output stage, the M 147 Tube uses a transformerless output stage.

This circuit design – proved to be effective in the “TLM” series of microphones – is especially insensitive to capacitive (cable) loads. The microphone can therefore be connected to long cables without the risk of high- frequency distortion. Also due to the transformerless circuit design the sound of the medium and lower frequencies is entirely determined by the capsule and the tube. Earlier tube microphones used a transformer which affected the sound quality depending on the volume, the frequency, and the load. The transformerless circuit design of the M 147 Tube provides a very good common mode rejection factor just like a transformer. It effectively attenuates signals influencing the balanced audio signal.

The M 147 Tube has a typical studio microphone’s sensitivity of approx. 20 mV/Pa. Internally, the tube amplifies the capsule signal by 10 dB. Thus, the sound of the M 147 Tube is exclusively determined by the tube, not by the following output stage. The microphone‘s inherent self-noise is exceptionally low: the noise level is 3 … 5 dB lower than that of comparable tube microphones. The head grille of the M 147 Tube has a slightly reduced shape as that of the U 47. The capsule as well as the whole circuit are decoupled from housing to protect it against handling and structure-borne noise.

Additional Information on the M 147 Tube Circuit Design

In contrast to other tube microphones, the M 147 Tube uses a combination of a specially selected triode and state-of-the-art circuitry. The developers‘ aim was both to utilize the advantageous properties of a vacuum tube for amplifying the capsule signal and to exclude any interference from other parts of the circuitry when the amplified signal is fed to the microphone output. This is why the M 147 Tube – unlike conventional tube microphones – does not use an output transformer but an integrated amplifier to drive the different output loads. This special audio amplifier features an extremely low THD, low self-noise, and high current capacity. Thus, the vacuum tube is entirely decoupled from the microphone output, and the typical tube characteristic can be used for processing the highest input signal levels. In contrast to conventional tube microphones, the high output current of the M 147 Tube allows cable lengths of up to 300 m without risking a deterioration of signal quality.

The tube amplifies the capsule voltage by about 10 dB to exclude any remaining impact of the electronics on the microphone signal. Despite this amplification, the dynamic range of the M 147 Tube remains very wide as the microphone delivers a peak output voltage of ± 10 V at 20 mA. During its entire life, the operating point of the tube is kept stable. This refers both to the anode current and to the heater voltage which is stabilized by a control loop in the power supply unit. Cable losses of up to 4 V DC – which corresponds to a cable length of approx. 100 m between the microphone and the power supply unit – are detected and compensated for by a sensor line. A breakdown of this line due to a short circuit or an open circuit is not dangerous as the heater voltage would automatically be reduced and all other voltages switched off.

To ensure a long life, the tube is heated very gently by current limiting with foldback characteristics. The operating voltages for the M 147 Tube are delivered by the power supply unit N 149 A using a switching regulator. Analog pre-controlling and two-stage active filtering at the switching regulator‘s output ensure high-quality operating voltages with a minimum of unwanted interfering voltages. The signal output of the power supply unit is provided with special protective circuitry so that the microphone can be connected to audio inputs with 48 V phantom powering without any problems. The load on the phantom power source will be approx. 1 mA.

Getting Started

The M 147 Tube comes complete with a KT 8 eight-core microphone cable, N 149 A power supply unit, SG 1 swivel mount, and an aluminum case. The stand connector of the SG 1 swivel mount has a 5/8″-27 internal (female) thread and comes complete with an adaptor to convert to 1/2″ and 3/8″ threads. A cloth dust cover is included to protect the microphone capsule.

This provides breathable, effective protection against contamination if the microphone goes unused for long periods. When hooking up the microphone, the order in which the cables are connected does not matter. A sensor in the power supply ensures that the operating voltages are not run up until the microphone is connected properly. The LED on the power supply then changes from a low glow to shine brightly.

Within a few minutes, at the latest, the tube in the M 147 Tube reaches its stable operating condition and then evidences its particularly low residual noise level. External phantom power, if present, does not detract from the performance of the M 147 Tube. If an external phantom power source is switched on or off, only a short, slight rise in the residual noise level will result. The on/off switch of the N 149 A functions as a secondary voltage interrupt for the feeds from the built-in mains unit.

To save energy, the N 149 A should be unplugged from the wall outlet if it is not in operation for an extended period. The M 147 Tube must only be operated with the Neumann power supplies N 149, N 149 A or N 149 V. Depending on the application in question, we recommend using the following accessories to enhance signal quality and protect the microphone from contamination:

• EA 1 Elastic Suspension
• WS 87 Windscreen
  PS 10 and PS 20 Popscreen.

For details, see the topic “Accessories”.

Type and Configuration of the Microphone and Power Supply Outputs
The microphone is finished in matt nickel. The 8-pin connector of the microphone and the corresponding connector of the power supply unit have the following configuration:

• Pin 1: –70 V
• Pin 2: +5 V
• Pin 3: audio signal, +phase
• Pin 4: +70 V
• Pin 5: sensor line
• Pin 6: ground
• Pin 7: +32 V
• Pin 8: audio signal, –phase

The included eight-core cable connects the microphone to the N 149 A power supply unit. At the power supply unit, the audio signal is available at a 3-pin XLR socket which requires an XLR- 3F connector. The pin assignment corresponds to DIN 45599, part “I” and IEC 268-12 (pin. conn. 130-x-IEC 02), respectively. An increase in sound pressure at the microphone‘s front diaphragm produces a positive voltage at pin 2.

Microphone Cables
The following cables are available for the M 147 Tube:

KT 8 …………………………………. blk ………………………… Cat. No. 08407 (included in the supply schedule)
10 m microphone cable with 8-pin DIN 45326 connectors. For connecting the microphone to the N 149 A power supply unit. Included in the scope of delivery.
IC 3 mt …………………………… blk ………………………… Cat. No. 06543
10 m long microphone cable, 5 mm in diameter, with a double twist (double helix) braiding as a shield. Three-pin XLR connectors, matt black. For feeding the audio signal to mixing consoles, etc.

Custom-made cables are available on request.
The M 147 Tube microphone is especially insensitive to capacitive loads. Even the use of long cables does not cause TIM or frequency response distortions. Thus, the audio signal cable can have a length of up to approx. 300 m, the 8-core connecting cable between the microphone and the power supply unit can be as long as approx. 100 m.

Power Supply Unit

The N 149 A (included in the supply schedule) power supply unit is available in the following versions:

• N 149 A Euro ……………… blk ………………………… Cat. No. 08447
• N 149 A US …………………. blk ………………………… Cat. No. 08446
• N 149 A UK ………………… blk ………………………… Cat. No. 08448

The three available versions of the N 149 A just differ in their enclosed main power cable. The N 149 V vintage power supply unit is available in the following versions:

• N 149 V Euro …………………………………. Cat. No. 12253.00101
• N 149 V US ……………………………………… Cat. No. 12253.00201
• N 149 V UK …………………………………….. Cat. No. 12253.00301

The three available versions of the N 149 V just differ in their enclosed main power cable.

Operation with Unbalanced Inputs
At the N 149 A power supply unit, the audio signal is available at a balanced XLR-3 output. The pin assignment corresponds to DIN 45 599, part “I” and IEC268-12 (pin. conn. 130-x-IEC 02), respectively:

• Pin 1: 0 V, ground
• Pin 2: audio signal, +phase
• Pin 3: audio signal, –phase

So pin 2 is the “hot phase”, pin 3 must be connected to the ground when used with unbalanced inputs (see figure 1).

Specifications

M 147 Tube

• Acoustic operating principle ………… pressure gradient transducer
• Polar patterns ………………………………………………………… cardioid
• Frequency response ………………………………. 20 Hz…20 kHz
• Sensitivity 1) …………………………………………………………………………. 20 mV/Pa
• Nominal impedance ………………………………………….. 50 ohms
• Nominal load impedance ………………………….. 1000 ohms
• Equivalent SPL CCIR 468-3 …………………………………. 24 dB
• Equivalent SPL DIN/IEC 651 …………………………. 12 dB-A
• S/N ratio CCIR 468-3 …………………………………………….. 70 dB
• S/N ratio DIN/IEC 651 ………………………………………….. 82 dB

Max. SPL (tube characteristic)

• for THD < 0.5 % ……………………………………………………. 114 dB
• for THD < 5 % ……………………………………………………….. 134 dB

Dynamic range of the amplifier

• DIN/IEC 651
• for THD < 0.5% 2) ……………………………………………………………….. 102 dB
• for THD < 5% …………………………………………………………. 122 dB
• Max. output voltage …………………………………………………. 8 dBu
• Power supply ……………………………………………………….. N 149 A

Required connectors:

• Microphone ………………………… Binder 8-pin (DIN 45326)
• Power supply unit …………………………………………………. XLR 3F
• Weight ………………………………………………………………………….. 460 g
• Dimensions ………………………………….. Ø 57 mm x 142 mm

1 Pa = 10 μbar
0 dB = 20 μPa

• at 1 kHz and 1 kohm nominal terminating impedance. 1 Pa = 94 dB SPL.
• THD of the microphone amplifier at an input voltage which is equivalent to the capsule output voltage at the specified SPL.

Frequency Response and Polar Patterns

Accessories

Further articles are described in the catalog “Accessories”.

Swivel Mount
SG 1 ………………………………….. blk ………………………… Cat. No. 08445
(included in the supply schedule)
The SG 1 swivel mount connects to the bottom part of the M 147 Tube microphone, which then can be mounted to a microphone stand. The microphone mount of the SG 1 is made of metal. The swivel mount has a 5/8″-27 thread, and a thread adapter for connecting to 1/2″ and 3/8″ studs.

Table and Floor Stands

MF 3 ………………………………… blk ………………………… Cat. No. 07321
Table stand with iron base, 1.6 kg, 110 mm in diameter. The table stand has a matt black finish and rests on a nonskid rubber disk attached to the bottom. A reversible stud and a reducer for 1/2″ and 3/8″ threads are also supplied.

MF 4 ………………………………… blk ………………………… Cat. No. 07337
Floor stand with grey cast iron base, 2.6 kg, 160 mm in diameter. The floor stand has a matt black finish and rests on a nonskid rubber disk attached to the bottom. A reversible stud and a reducer for 1/2″ and 3/8″ threads are also supplied.

Stand Extensions
The STV… stand extensions are used between the microphone and floor stands to provide table or floor stands of variable heights.

The STVs are 40, 200, 400 or 600 mm long. Diameter: 19 mm.

• STV 4 ……………………………….. blk ………………………… Cat. No. 06190
• STV 20 …………………………….. blk ………………………… Cat. No. 06187
• STV 40 …………………………….. blk ………………………… Cat. No. 06188
• STV 60 …………………………….. blk ………………………… Cat. No. 06189

Auditorium Hanger and Suspensions

• MNV 87 …………………………. ni …………………………… Cat. No. 06804
• MNV 87 mt ………………….. blk ………………………… Cat. No. 06806

The auditorium hanger consists of a cable suspension and a rotating 1/2″ threaded stud. It is used together with a swivel mount. The stud is screwed into the threaded coupling of the swivel mount. Then the microphone can be tilted while it is suspended from its own cable.

Elastic Suspension
The use of an elastic suspension is recommended to prevent the microphone from being exposed to strong mechanical vibrations caused by structure-borne shock waves.

• EA 1 …………………………………. ni …………………………… Cat. No. 08449
• EA 1 mt …………………………. blk ………………………… Cat. No. 08450

The EA 1 is designed for the TLM 103, TLM 193, and M 147 Tube microphones. It has a swivel mount with a 5/8″-27 female thread that can be fastened to tripods. Included is a threaded adapter to connect to 1/2″- and 3/8″ studs.

Windshields
To protect against noise caused by wind, close talking, and rapid movement on a boom, open cell polyurethane foam windshields are available. These windshields have no disturbing resonances and do not affect the microphone’s directional characteristics. The frequency response is only slightly attenuated in the higher frequency range.

WS 87 …………………………….. blk ………………………… Cat. No. 06753
Windscreen for M147 Tube. The diameter is approx. 90 mm. Suppression of the wind noise approx. 26 dB. Attenuation at 15 kHz approx. 3 dB. Color black.

Pop screens

• PS 10 ……………………………….. blk ………………………… Cat. No. 07345
• PS 20 ……………………………….. blk ………………………… Cat. No. 07346

The PS 10 and PS 20 pop shields provide excellent suppression of so-called pop noise. They consist of a round, thin wooden frame covered with black gauze on both sides. The stand adaptor with 5/8″-27 female thread can be altered by 230°. A reducer for connection to 1/2″ and 3/8″ studs is included. For mounting a pop shield to the MKV quick-release clamp, a double-sided stud with locknut is included in the supply schedule. Used in conjunction with the MKV quick-release clamp the pop shields can be attached to stands or connectors

SERVICE

• Ollenhauerstr. 98
• D-13403 Berlin
• Tel.: +49-30 / 41 77 24-0
• Fax: +49-30 / 41 77 24-50
• Email: headoffice@neumann.com
• Web: www.neumann.com

LAGER

• Am Labor 1
• D-30900 Wedemark

FAQs

What is the Neumann M147 Cardioid Tube Condenser Microphone?

The Neumann M147 is a high-quality tube condenser microphone designed for professional audio recording, known for its warm and vintage sound.

What type of microphone is the Neumann M147?

The Neumann M147 is a tube condenser microphone, prized for its ability to capture vocals and instruments with a rich and classic tonal character.

Is the Neumann M147 suitable for studio recording?

Yes, the Neumann M147 is a studio-grade microphone, and it excels in capturing high-quality audio for various studio applications.

What is the frequency response of the Neumann M147?

The Neumann M147 typically has a frequency response ranging from 20Hz to 20kHz, ensuring accurate and detailed audio capture.

Does the Neumann M147 require phantom power?

No, the Neumann M147 is a tube microphone, and it requires its dedicated power supply, which is included with the microphone.

Can I use the Neumann M147 for live performances?

While it's primarily designed for studio use, the Neumann M147 can be used for live performances with the appropriate setup and power supply.

What type of polar patterns does the Neumann M147 support?

The Neumann M147 offers a cardioid polar pattern, which is great for isolating sound sources and reducing background noise.

Is there a shock mount included with the Neumann M147 microphone?

Yes, the Neumann M147 often comes with a shock mount to reduce vibrations and handling noise during recording.

What are the dimensions and weight of the Neumann M147 microphone?

The Neumann M147 is compact, with dimensions of approximately 9.7 inches (length) and a weight of around 21.2 ounces.

Can I use the Neumann M147 for recording vocals and instruments?

Yes, the Neumann M147 is versatile and suitable for recording both vocals and a wide range of musical instruments.

Does the Neumann M147 microphone come with a carrying case?

Yes, it typically comes with a protective carrying case to ensure safe storage and transportation.

What is the warranty for the Neumann M147 microphone?

The Neumann M147 microphone typically comes with a manufacturer's warranty to guarantee the quality of your purchase.

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