Shure 55AV, 55BV, 55CV User Guide

DATA SHEET No. 188

DATE:

SUBJECT: Models 55AV, 55BV, 55CV

“Voice Unidyne” Dynamic Microphones

55V SERIES "VOICE UNIDYNE" MICROPHONES

(CARDIOID UNI-DIRECTIONAL MOVING-COIL DYNAMIC)

GENERAL:	Models 55AV,	55BV and	55CV	are	uni-
	directional moving		coil	dynamic
	microphones	designed	especially		for

high quality reproduction of the speaking and singing voice. The true unidirectional characteristic of the "Unidyne", obtained by the "uniphase" principle provides highly satisfactory operation under adverse acoustic conditions where a conventional microphone would be practically useless. (See "Acoustic Considerations").

The microphone has a specially designed moving system containing a new type moving-coil element, operating in conjunction with a high flux magnet in the magnetic circuit providing high efficiency and smooth peak free response from 100 to 10,000 cycles. The rear response is down approximately 15 db due to the "uniphase" unidirectional acoustic network.

The case is modern in design with attractive streamlining and grille treatment. The head tilts through an angle of 90° to permit aiming at the source of sound for best pickup. A built-in cable connector is provided and a 12 ft. shielded rubberjacketed cable with microphone plug attached is included.

APPLICATIONS: Models 55AV, 55BV and 55CV are suitable for high quality public address and broadcasting and recording of

voice. They are particularly satisfactory as a soloist’s microphone, for announcing at sport events, and also for communications and paging especially when background noise is present. "Voice Unidynes" are not intended for high fidelity reproduction of music. For this purpose the 55 and 555 Series microphones are recommended. The true unidirectional characteristic of the "Unidyne" provides an easy solution to the feedback problem in reverberant locations, facilitates orchestral placement, permits best utilization of space in small broadcast studios, and allows practically complete exclusion of unwanted noises. The swivel allows the head to be tilted through an angle of 90°, permitting the microphone to be aimed at the source of sound.

The instrument is unusually rugged and is practically immune to the effects of moisture, temperature and mechanical vibration.

INSTALLATION: All microphones have the standard 5/8"-27 thread and may be mounted

on any Shure desk, banquet, or floor stand. Shure floor stands are especially recommended because of the effective isolation against floor vibration which they provide. For overhead suspension, an A35B Suspension Adapter may be used.

CONNECTIONS: Model 55AV works directly into a 3550 ohm line while models 55BV and 55CV include an internal high quality

impregnated transformer with special high-permeabil- ity core. The three models, their out-put impedances, and cable furnished are listed below.

MODEL		IMPEDANCE	CABLE FURNISHED
55AV -		35-50 ohms	12 ft. two-conductor
55BV - 200-250 ohms			12 ft. two-conductor
55CV	-	high impedance	12 ft. single conductor

Low impedance models 55AV and 55BV are recommended where long cable lengths are required. The permissible line length is practically unlimited since neither the level nor the frequency response is appreciably affected by reasonable lengths of

line. As shown in the table below, the cable loss is very small. When long lines are used, care should

be taken that the cable does not parallel A.C. power lines for long distances to avoid A.C. hum induction.

CABLE	LENGTH	LOSS	IN	LEVEL*	LOSS IN	LEVEL*
CABLE	LENGTH	MODEL		55A	MODEL	55B
		MODEL		55A	MODEL	55B
12	ft.		0	db	0	db
25	ft.		0		0	db
250	ft.		0.4	db	0	db
500	ft.		0.8	db	0.2	db
1000	ft.		1.6	db	0.4	db
2000 ft.			2.9	db	0.7	db

*Based on 2-conductor #20 equivalent, twisted and shielded.

Low impedance models 55AV and 55BV may be fed into a standard low impedance input amplifier (see Fig. A-3) or into an amplifier with high impedance input (Fig. A-2). In the latter case Shure Model A86A Cable-Type Transformer is available for coupling the low impedance line to the amplifier input. The double-winding primary permits coupling either a 35-50 ohm line or 200-250 ohm line to the high impedance input.

High impedance model 55CV may be used with any crystal microphone amplifier or other amplifier with an input impedance of 100,000 ohms or more (see Fig. A-l). For best high frequency response, the total cable length should not exceed 25 feet; longer cable lengths may be used with some loss of high frequency response. The additional loss at 5,000 cycles is of the order of 2.5 db for an additional 25 ft. length of cable (50 ft. total) and 6 db for additional 50 ft. length (75 ft. total).

OPERATION: The microphone should be placed in its operating position before turning

up the volume controls of the amplifier. Jarring or excessive moving of the instrument should be avoided while the system is in operation in order to prevent the spring-suspended microphone unit from touching the inside of the case and producing undesirable noises.

No special precautions beyond ordinary care are necessary in the operation of 55V Series Dynamic microphones. They will operate efficiently and dependably under all ordinary conditions in hot and cold climates. To retain the full strength of the highly efficient permanent magnet and to maintain

ACOUSTIC

CONSIDERATIONS:

DATA SHEET

alignment of the structure, dropping or other severe mechanical shocks should be avoided.

The expression "cardioid type" response simply means that the horizontal polar characteristic approximates a cardioid. There is a wide, useful

pickup angle at the front of the microphone while the response at the sides is down 6 db from the front response. The rear response in practical cardioid type microphones is down of the order of 15 db from the front side response. The Unidyne fulfills these requirements over a broad range of frequencies. The true unidirectional characteristic of the "Unidyne" should not be confused with the relatively slight directional effect at high frequencies only which can be produced by‘ baffle effects in the conventional pressure microphone.

The result of this unidirectional characteristic is a complete elimination of acoustic feedback at volume levels which would cause considerable feedback with conventional semidirectional microphones. In practically all cases it is possible to increase loudspeaker levels when a Unidyne is installed. By directing the dead side (rear) of the microphone towards the audience or other source of interfering sound, pickup can be concentrated on the desired source. Reverberation energy pickup is decreased approximately two-thirds. The microphone can be placed close to reflecting surfaces without objectionable effects if the rear side of the microphone is toward the reflecting surface. This is Particularly valuable in small broadcast studios.

It is desirable to experiment with microphone Placement and orientation in order to secure the greatest benefits from the unidirectional characteristic.

S P E C I F I C A T I O N S

VOLTAGE SENSITIVITY:

MODEL 55AV - 62/8 db below 6 milliwatts for 10 bar signal when loaded with 35-50 ohms.

MODEL 55BV - 74db below 1 volt per bar open circuit, or 63.8 db below 6 milliwatts for 10 bar signal when loaded with 200-250 Ohms.

MODEL 55CV - 55.5 db below 1 volt per bar when loaded with 100,000 ohms or more. This is equivalent to 1.8 millivolts per bar across 100,000 ohms or more.

RECOMMENDED LOAD IMPEDANCE:

MODEL 55AV - 35-50 ohms.

MODEL 44BV - 200-250 Ohms.

MODEL 44CV - 100,000 ohms or more.

Patented

Shure Brothers

MODEL

55AV

55BV

55CV

Code

Word

RUVAK

RUVAD

RUVAG

Net

Wt. Less Cable

2¾

lb.

2¾

lb.

2¾ lb.

Shipping Weight

3½

lb.

3½

lb.

3¼

lb.

ft.

Cable

Two-

Single

Conduct

Conductor

Height,

Overall

(a)*

7-25/32"

Height,

Case

(h)*

4- 7/16"

Width

(b)*

3- 3/16"

Thickness

(c)*

3- 9/16"

Finish

Satin

Chrome

* See

Fig. C.

FREQUENCY RESPONSE OF 55V SERIES MICROPHONES AT VARIOUS DISTANCES FROM THE SPEAKER'S LIPS

GUARANTEE: Each microphone is guaranteed to be free from electrical and mechan-

ical defects for a period of one year from date of shipment from the factory, provided all instructions are complied with fully. In case of damage, return the microphone to the factory for repairs. Our guarantee is voided if the microphone case is opened.