Shure FP51 Schematic

222

HARTREY AVENUE

SHU-

THE SOUND OF THE PROFESSIONALS'

..+

GENERAL

The FP51 is a compact, portable, high-quality gated memory dian Standards Association as Certified compressor combined with a four-input, one-output microphone mixer. Designed for applications in broadcasting, recording and sound reinforcement, the FP51 integrates all the features of professional compressors and mixers in a single unit-small and lightweight enough for location use, but with the reliability of a studio console.

FEATURES

40 dB compression range, with compression ratio approximately 10:l in normal operating range

Gated memory minimizes "pumping," has LED indicator True average-responding compression maximizes output

level regardless of peak-to-average ratio of program material. Peak-responding circuit reduces gain rapidly for significant increases in input signal

Front-panel response rate adjustment (averaging time constant) compensates for variations in program material

Extremely low distortion, noise and RF su'sceptibility, with wide, flat frequency response at all compression levels

Reliable operation under wide temperature and humidity conditions

Protected against damage from input overload and shorted outputs

Four transformer-coupled XLR inputs, each microphonelline switchable with low-cut filter and cuing functions

Phantom power for condenser microphone operation Built-in tone oscillator permits checking levels and testing

lines

Transformer-coupled XLR output with microphonelline switch

Headphone jacks (114-inch and mini-3.5 mm) with level con-

trol Active, feedback-type input gain controls allow high-level

input signals without input attenuators Illuminated triple-function VU meter indicates output level,

dB compression and battery condition Powered by ac (120V or 240V-internally selectable) or

built-in battery pack gain (line) Low battery drain provides up to 10 hours operation under

normal conditions Noiseless and automatic switchover to and from battery

power without affecting compressor Rugged, durable construction than 15 dB Compact and lightweight for field use and transporting Rack-mountable with accessory rack mount kit

27A2216

1989,

Shure Brothers Inc.

(IJ)

@EVANSTON, ILLINOIS

60202-3696

PROFESSIONAL

Listed by Underwriters Laboratories Inc.; listed by Cana-

SPEClFlCATlONS

Frequency

30 to 20,000 Hz,

Voltage Gain

Inputs

*Dependent on input control setting.

outputs

Headphones

Compressor

Response

INPUT

Line 55dB 5dB -25dB 65dB 45dB

Mix

Bus 70dB 20dB

INPUT

Line

Mix Bus >3.5k 3.5k +2 dBV

OUTPUT

Mic Line

Mix

Bus

Threshold: -88

Ratio:

Attack Time: 3 msec for level increases greater than 15

Recovery Time: 120 msec to

2 dB

(at 1 kHz)

lMWX)ANCE

FOR USE

25-600Q mics

level sources

WJEDANCE

FOR USE WITH

25-600Q mic circuits

600 ohms

3.5k

8-2000 ohms

dBV typical at maximum input gain

(mic); -38

8:l minimum from 10 to 20 dB comprssion 5:l minimum from 10 to 30 dB compression

dB; 120

USA.

PRODUCTS

OUTPUT

MIX BUS PHONES (CUE)

(at 1 kHz)

WITH ACTUAL LEVEL AT 1 kHz

(at 1 kHz)

ACTUAL

1 ohm or

less

185 ohms

3.5k

100 ohms

dBV typical at maximum input

msec to 6 sec for increases of less

sec

INPUT CLIPPING

OUTPUT CLIPPING

LEVEL AT 1 kHz,

-34 dBV min.

(150-ohm load)

(600-ohm load)

-7

(3.5k load)

(200-ohm load)

PHONES

80dB

THD

18 dBm min.

dBV min.

7 dBV min.

Printed in

U.S.A.

I-

--I

V) V)

111

;

INPUT LEVEL

IMIC

dBV

COMPRESSION SYSTEM

INPUT-OUTPUT CHARACTERISTICS

FIGURE

Gated Memory

Threshold: -90.5 dBV typical at maximum input

gain (mic); -40.5

dBV typical at max-

imum input gain (line)

Recovery: In "hold" position, less than 20 dB gain

recovery after 1 minute

VU Meter

Dual-range, 3-function (output level in dB, gain reduction in dB, battery check), illuminated (ac operation only)

Gated MemorylPeak Indicator

With meter switch in VU position, lights 6 dB below clipping; with meter switch in

Comp position, lights when gated

memory is "holding"

Noise

Equivalent lnput Noise: - 129 dBV (low-impedance microphone, 150 ohms, 300 to 20,000 Hz) into 600-ohm load at full gain

Equivalent lnput Hum and Noise: -127

dBV (lowimpedance microphone, 150 ohms, 20 to 20,000 Hz) into 600-ohm load at full gain

Output Noise: -77 counterclockwise [off]), -40

dBV maximum (output control full

dBV maximum (output control

full clockwise [on]) (input control down, 300 to 20,000 Hz)

dBV maximum (output con-

Output Hum and Noise: trol down), -38

dBV maximum (output control up, input con-

-75

trol down, 20 to 20,000 Hz)

Distortion

0.4% THD, 30 to 20,000 Hz at + 15 dBm output; 0.5% or less

IM distortion at + 15 dBm output into 600 ohms

Common Mode Rejection

65 dB minimum with input of -20 dBV at 100 Hz

Control Interaction

Less than 1 dB with any control combination

Overload and Shorting Protection

Shorting outputs, even for prolonged periods, will cause no damage; microphone input will not be damaged by signals

up to 3V

Low-Cut Filters

6 dB per octave rolloff at 150 Hz

Phase

All outputs in phase with respect to all inputs. Pin 2 is "high" with respect to pin 3; pin 1 is ground. Tip of mix bus jack in phase with pin 3. Tip and ring of headphone jacks in phase with pin 2

Tone Oscillator

1 kHz; + 15 dBm minimum at line output with output level

full up

Phantom Power

30 Vdc nominal, 3.3k series resistance, automatically disabled with input switch in Line position

Operating Voltage

Ac Operation: 120 or 240 Vac -r-10% (internally selectable), 50160 Hz,

5.5W

Dc Operation: 30

mA typical at 0 VU (+4 dBm) output; 21.5 Vdc minimum;

Vdc nominal at 27 mA typical no-signal,

battery life approximately 10 hours with alkaline batteries

4 dBm output in continuous use; three 9-volt bat-

at teries, type NEDA

1604A (Duracell MN1604 or Eveready 522

recommended)

Temperature Range

Operating: -18O to 57OC (0° to 135OF) Storage: -2g0 to 71°C (-20° to 160°F)

Dimensions

79.5 mm H x 310 mm W x 230 mm D (3-118 in. x 12-7132 in. x 9-1132 in.)

Weight

Net: Packaged:

2.75 kg

3.25 kg (7

02)

Ib 3 oz)

Certifications

Listed by Underwriters Laboratories Inc.; listed by Canadian Standards Association as Certified

CONTROLS AND CONNECTORS Power Off-On Channel Levellcue

Switch: applies power to the FP51 circuitry.

Rotary Controls: adjust individual input channel signal levels. Each channel can be cued by pulling the control knob outward to the detent position, rotating the knob to the desired level, and pushing the knob inward to activate

'the channel.

Lo Cut Filter

Slide Switches: reduce unwanted low-frequency

signals such as wind noise by 6 dB per octave at 150 Hz.

Master

Rotary Control: determines mixed output level at output connector. The control also sets the tone oscillator level when the

Gated MemorylPeak

Tone Osc

switch is turned on.

indicates, in gated memory mode,

LED: that gated memory is "holding" prior amount of compression during a low input signal, and turns off when input signal is above compression threshold. In peak mode, the LED indicates approaching program overload. It is activated by the shortest transient peak, but remains on long enough to provide easy recognition. The chart below shows the effect of

Compressor

and

Gated Memory

switches on indicator opera-

tion.

GATED MEMORYIPEAK LED FUNCTIONS

Gated

Memory

off

Gated

Memory

Compressor Compressor

VU Meter:

out No operation

in Gated memory

indicates

0 VU with a +4 dBm output (recommended for normal use to provide approximately 14 dB headroom from operating level to clipping level) with

switch in VU position. Rear-panel switch permits changing to

0 VU = +8 dBm. With

VU Range +41+8

VUlComp

slide

VUlComp

switch in Comp position, indicates compression due to input signal above threshold (lower meter scale). The VU meter is lit during ac operation only; therefore, the illumination serves as a visual alarm if the ac is interrupted and the unit has automatically switched to battery operation.

Batt Check

junction with the the batteries will give about a

Momentary Push-button Switch:

VU meter to indicate battery condition. With

Power

switch on and the switch depressed, a new set of

is good if the reading is above

VU indication. Battery condition

0 VU; a lower reading means

operates in con-

that new batteries are required for proper operation.

Gated Memory

Slide Switch: disables the gated memory

function without affecting other operations.

Response Rate

Rotary Control: adjusts the compression system time constant to compensate for different types of program material. In general, a faster setting (toward the counterclockwise position) results in a more constant output

level, but a more audible compression effect. Although the control setting is subjective, the following knob positions offer guidelines: speech -2; pop music -4; symphonic music- 7.

Compressor Off-On

and gated memory functions, converting the FP51 to a standard microphone mixer.

Tone Osc Off-On

distortion 1 kHz tone for line tests and level checks. The tone signal level is controlled by the signal appears on both the well as the oscillator should be switched off when not in use.

Headphones

Jack: permit monitoring mixer output through most stereo headphones. The put level of both jacks. Note that the headphones output level is high enough for use as an auxiliary unbalanced line feed to drive a tape deck or a power amplifier.

lnput

1-4

sional three-pin audio inputs. Pins 2 and "neutral," and pin 1 is ground. For microphone operation, the

XLR Connectors: are transformer-balanced, profes-

lnput MiclLine

level inputs, the switches must be in the Line position.

Phantom Off-On

phantom power for condenser microphones to all inputs. With the switch on and

+30 Vdc is applied to pins 2 and 3 of each input connector (power is automatically removed in the Line position). Series current-limiting resistance is 3.3 kilohms for each input. When using other than Shure microphones, verify that the voltage and resistance requirements are compatible.

Output

XLR Connector: is a professional three-pin audio connector for connection to either low-impedance microphone or line-level inputs of power amplifiers, mixers, or other signalprocessing equipment. The either microphone- or line-level output signals.

Line Out

balanced 600-ohm line. Terminals are in parallel with the 3-pin

Output

Line position only. The red terminal is in parallel with pin 2 of the pin 3. Note that the line-level output signal is always present on these terminals.

Mix Bus

put channel mixing bus. This facilitates stacking or "multing" FP5ls to achieve additional input capacity without losing any inputs. With two example, the mix buses of each unit are directly connected, providing two independent isolated line amplifiers with eight individually puts. Since the buses are directly connected, a 6 dB drop in the gain of each output channel will occur, and the

put

specifications are not adversely affected by this connection.

Push Terminals: provide direct wire connection to a

connector when the

Output

connector, and the black terminal is in parallel with

Phono Pin Jack: provides direct access to the out-

controls must be increased to compensate. Noise

Slide Switch: disables the compressor

Slide Switch: provides a highly stable, low-

Master Level

lipe and microphone outputs, as

and

Mix Bus

1M-inch Phone Jack and Miniature 3.5 mm Phone

Headphones

switches must be in the Mic position; for line

Slide Switch: controls the application of

lnput MiclLine

rotary control adjusts the out-

switches in the Mic position,

Output MiclLine

FP5ls connected at their

Master

control. The tone

connectors. The tone

are "hot" and

switch selects

switch is in the

Mix Bus

gain controls and two

jacks, for

control\ed in-

Master

In-

INSTALLATION AND OPERATION Battery Operation

In addition to 120- or 240-volt ac operation, the FP51 can be operated from an internal battery pack. Current drain is typically 30 recommended for remote, on-location operation, and as an emergency backup source in case of ac power failure.

Access to the battery compartment is through the bottom of the chassis. Three 9-volt transistor radio batteries power the FP51 at full rated batteries are recommended. Battery life is hours at loading will increase battery drain.

With batteries in the battery compartment, the FP51 will automatically and silently switch to battery operation should the ac voltage fall below a suitable level.

Battery condition can be determined using the switch on the front panel. With the FP51 tivate the set of batteries will give about a condition is good if the reading is above means that new batteries are required for proper operation.

mA at +4 dBm output level. Battery operation is

out~ut. Duracell MN1604 or Evereadv 522

+4 dBm continuous use. Note that ~hantom Dower

approximat~ly 10

Batt Check

Power

Batt Check

switch and observe the VU meter. A new

+2 VU indication. Battery

switch on, ac-

0 VU; a lower reading

Connections

Connect the signal sources to the three-pin XLR

nectors. Connect the three-pin XLR

Line Out

telephone line, etc. Set the

appropriate signal level.

puts, for information on increasing the number of available microphone- or line-level inputs.

phone jack, if desired, for monitoring the FP51 output.

the FP51 desired, refer to the Service section.

terminals to the input of a power amplifier, mixer,

to the Operating Hints section titled, Additional In-

Refer

Connect headphones to the phone jack or 3.5 mm mini Connect the line cord to a 120

is to be ac-operated. If 240-volt ac operation is

Output

Output MiclLine

Vac 2 lo%, 50160

lnput

source if

con-

connector andlor

switch for the

Adjustments

Turn the the or

trols fully counterclockwise to 0, and set the control for the program material to be used.

If desired, turn on the

nel Level

and undesirable low-frequency signals (see Figure

Note that each input capability. To cue a channel while the other channels are carrying program material, pull the desired trol outward to the cue position. This removes that channel from the mixing circuitry and routes it only to the jacks. Adjust the

listening level, and adjust the cued proper mixing level. Restore the cued signal to the program mix by pushing the

Turn on the

warmup time. The VU meter will light in ac operation. Turn the

Phantom

microphones are to be used with the turn the pedance microphones.) Note that phantom power cannot be applied to the inputs with the position; if line-level condenser microphones (such as Shure's SM82) are to be operated on phantom power, contact Shure's Service department for modification instructions.

Turn on the

approximately 10 on the VU meter lower scale will result, and

the

Set the for a heard in headphones connected to either phone jack. The tone signal can be used to calibrate equipment following the

Reduce the reading, and turn off the

MemorylPeak

memory is "holding" the prior amount of compression. Note the

reduction is made to compensate for the moderate short-term

output dynamic range encountered for speech using the

Compressor

VUlComp

switch to Comp, and the

dBm. Rotate the

and

Gated Memory

Channel Level

slide switches on,

VU Range

and

switch to + 4

Master Level

Response Rate

controls. The filter action will help reduce wind noise

Lo Cut Filter

FREQUENCY

LO CUT FILTER ACTION

FIGURE

Channel Level

switches above the

HERTZ

control has a cuing

Chan-

2).

Channel Level

Headphones

Channel Level

Power

switch and allow approximately 1 minute

switch on if non-battery-operated condenser

Phantom

switch on when using

Tone Osc

Gated MemorylPeak

VUlComp

0 VU meter reading (upper scale). The tone signal can be

Master

control setting for future use. (Note: This output

switch to VU and rotate the

Master

LED will turn on, indicating that the gated

control setting for a -2 VU meter

level control to a comfortable

Channel Level

control inward.

FP51.

MiclLine

switch. A dB compression reading of

LED will turn off.

Tone Osc

switches in the Line

switch. The

control for a

(Caution:

unbalanced

Master

low im-

control

FP51.

Gated

con-

not

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