SOUNDCRAFT 500 (01) PDF Document

The SOUNDCRAFT 500 is a modular monitor console designed for public address applications. Key features include:

• 12 group outputs, a Phones output, and a mono monitor output.

• All balanced inputs and outputs use an electronic, transformerless design for low inherent noise, superior transient response, minimal phase shift, and excellent common mode rejection.

• VU meters are provided for the 12 group outputs, with separate meters for the PFL signal and the Monitor level signal.

• Its modular construction makes maintenance straightforward.

• The console operates at +4dBu, while the internal operating level (including insert points) is at -2dBu, allowing for greater internal headroom.

• The power supply is a 19″ rack-mounted unit providing +/- 17V rails for audio, +24V for the LED display, and +48V for phantom power.

Each channel’s input section has the following controls:

a) +48: Pressing the +48 button enables the console’s internal 48 Volt Phantom Power supply to power capacitor microphones. It is not advisable to use a Direct Injection box when Phantom Power is on.

b) PAD: The PAD button inserts a 20dB attenuator into the microphone amplifier’s input, allowing for extremely high-level input signals without overloading the input stage.

c) LINE: The Line Input can be selected by pressing the LINE button.

d) GAIN: The GAIN trim control varies the gain for both Microphone and Line inputs between 20dB and 60dB. When used with the 20dB PAD, a 60dB control range is available for the Microphone input.

The equaliser provides five areas of control. All amplitude pots are center detented for easy zeroing.

a) THE HIGH PASS FILTER: Operates at 100Hz with a slope of 12dB/octave to remove low-frequency rumble.

b) HF (High Frequency): Provides 15dB of boost or cut at 8 kHz with a “shelving” characteristic.

c) HI MID: A continuously variable frequency control from 600Hz to 10kHz, with 15dB of boost or cut available. The response is a “bell” type with a “Q” (bandwidth measure) of 1.5.

d) LO MID: Identical to the Hi Mid section, but the frequency is variable between 150Hz and 2.4kHz.

e) LF (Low Frequency): Provides 15dB of boost or cut at 70 Hz with a “shelving” characteristic.

f) EQ BUTTON: Switches the equaliser circuitry in or out of the signal path, independent of the High Pass filter.

The SOUNDCRAFT 500 has twelve individual monitor sends, each with its own level control, permanently routed to the twelve monitor group outputs.

a) SENDS 9 TO 12: These are normally post-fade signals but can be switched to pre-fade by pressing the associated button marked PRE.

b) SENDS 5 TO 8: These are also normally post-fade signals but can be switched to pre-fade by pressing the associated button marked PRE.

c) SENDS 1 TO 4: These can be configured as pre/post fade and pre/post EQ depending on internal jumper selection.

• Pre fade and pre EQ: Place jumpers J2 and J3 ON.

• Pre fade and post EQ: Place jumpers J1 and J3 ON.

• Post fade and post EQ: Place jumpers J1 and J4 ON.

a) PHASE: Pressing the phase button corrects for miswired microphones and can be useful for cancelling feedback in on-stage monitoring.

b) CHANNEL FADER: This is a rotary control calibrated from 0 to 10 that provides overall level control for the channel.

c) ON: Pressing the ON button enables the monitor sends for the channel.

d) DIM: Pressing the DIM control attenuates the channel signal by -6dB. This is particularly useful if sudden feedback occurs.

e) PFL: Pressing PFL soloes the pre-fade signal, independently of the ON switch. Operation is indicated by a red LED.

Each monitor output has a three-band equaliser with a parametric mid-range:

a) HF: The high frequency is a shelving type and provides 15dB of boost or cut at 10kHz.

b) MID: The parametric mid frequency control is a ‘bell’ type, providing 15dB of boost or cut over a frequency range of 450Hz to 7.2kHz. The Q of the filter can be varied to give narrow or broad-band control.

c) LF: The low frequency control is a shelving type and provides 15dB of boost or cut at 100Hz.

The rotary monitor level control contributes to the mono mix available via the SUB level control on the Master module. Pressing the PRE button changes the signal source depending on internal jumper selections.

Pre insert point: Install jumper J13 for odd numbered groups and J15 for even numbered groups.

Pre fader: Install jumper J14 for odd numbered groups and J16 for even numbered groups.

Note: each jumper has two possible positions.

a) ON: The ON button enables the module.

b) PFL: Pressing PFL soloes the pre-Fade signal.

c) GROUP FADER: The two group faders control the overall group output level. Odd numbered groups are controlled by the lefthand fader and even numbered groups by the righthand fader.

a) MIC LEVEL: Adjusts the level of the talkback signal.

b) ROUTING: The talkback signal can be routed to any of the twelve monitor output groups. The talkback source is determined by the small EXT button. When this is pressed, the talkback signal is an incoming external signal.

When talkback is in operation, the signals from the PFL and SUB buses are dimmed by 20dB.

Pressing the large INT button turns on local talkback and feeds a small amount of signal to the headphones circuit.

Pressing the large EXT button routes the local talkback to the T/B out socket on the rear connector panel and sends a small amount of signal to the headphones circuit. This is designed to interface with the Soundcraft Series 8000 talkback system.

PFL: The PFL level control allows adjustment of the amount of PFL signal present in the monitor and headphone outputs.

SUB: The SUB level control allows adjustment of the amount of Monitor signal, provided by the monitor level controls on the Group outputs, in the Monitor and headphone outputs.

Phones: The phones level control allows the level in the headphone output to be adjusted independently of the Master fader.

Insert point: An unbalanced insert point is available immediately before the Monitor output fader.

Monitor output fader: The Master fader controls the amount of signal present on the mono output.

1) Line Inputs (Stereo Jacks):

• Tip: HOT (In phase signal)

• Ring: COLD (Out of phase signal)

• Sleeve: GROUND

2) Mic Inputs (XLR):

• Pin 1: GROUND

• Pin 2: HOT (In phase signal)

• Pin 3: COLD (Out of phase signal)

3) Channel Inserts (Stereo Jacks, Unbalanced):

• Tip: Insert return

• Ring: Insert send

• Sleeve: Common Ground

4) Line Outputs (Stereo Jacks, Unbalanced):

• Tip: HOT (In phase signal)

• Ring: Signal Common

• Sleeve: Signal Common

1) Monitor Group Inserts:

• SEND (Unbalanced): Tip: HOT (In phase signal), Ring: Common ground, Sleeve: Common ground

• RETURN (Balanced): Tip: HOT (In phase signal), Ring: COLD (Out of phase), Sleeve: Ground

2) Monitor Group outputs (XLR, Electronically Balanced):

• Pin 1: GROUND

• Pin 2: HOT (In phase signal)

• Pin 3: COLD (Out of phase signal)

3) Talkback Input (XLR):

• Pin 1: GROUND

• Pin 2: HOT (In phase signal)

• Pin 3: COLD (Out of phase signal)

4) Talkback output (XLR):

• Pin 1: GROUND

• Pin 2: HOT (In phase signal)

• Pin 3: COLD (Out of phase signal)

5) Monitor Output (XLR):

• Pin 1: GROUND

• Pin 2: HOT (In phase signal)

• Pin 3: COLD (Out of phase signal)

Before switching on the SOUNDCRAFT 500 console, check that the mains voltage selector on the power unit is set at the correct mains voltage for your area, and that the fuse is of the correct rating.

• For operation on voltages between 220 and 240V AC, the fuse should be rated at 3.15A, 20mm, anti-surge.

• For operation on voltages between 100 and 120V AC, the fuse should be rated at 6.30A, 20mm, anti-surge.

All XLR type connections are normally wired to the following standard:

• Pin 1: GROUND

• Pin 2: HOT (In phase signal)

• Pin 3: COLD (Out of phase signal)

All inputs and outputs are electronically balanced except for the Monitor Channel Insert and Line Out.

For optimum performance and a clean, noise-free earthing system, follow these considerations:

a) Establish a central earth point. All earths should be “star fed” from this point. Run an individual earth wire from each outlet back to the system star point.

b) Install separate “clean” and “dirty” mains outlets, wired individually back to the mains distribution box. Use the “clean” supply for audio equipment and the “dirty” supply for lighting, etc.

c) If necessary, install an isolating transformer with a Faraday Shield (connected to earth) for the “clean” supply to isolate from mains-borne interference.

d) Never locate the incoming mains distribution box near audio equipment, especially tape recorders, which are sensitive to electro-magnetic fields.

e) Ensure that all equipment racks are connected to earth via a separate wire back to the star point.

f) Equipment with unbalanced inputs and outputs may need to be isolated from the rack to prevent earth loops.

To ensure a quiet, stable system, connect equipment in the following logical sequence:

a) Connect the Control Room Monitor system to the console and check for any hum, buzz, or RFI. Proceed only when you are satisfied with the quietness.

b) Connect the multitrack tape recorder (via noise reduction if applicable) and check again that the system is still clean.

c) Connect stereo tape recorders, studio monitors, echo, and foldback sends one at a time, checking and isolating any connection that degrades performance.

d) Connect all peripheral devices.

e) Connect all microphone lines.

To minimize unwanted coupling, it is important that the screen is connected at one end only. In general, always connect the shield only at the signal source end. The optimum screen connection depends on the type of output and input being connected, as shown in the table below:

Note 1: The shield is connected to the destination earth point because the signal wires being shielded are referenced to the input earth, not the output earth.

Note 2: If the output transformer is centre tapped to earth, the screen should be connected at the source.

Note 3: When an active differential output is operated in unbalanced mode, it is very important that the output current returns to earth via the shortest, least reactive route. Check for instability at the output.

To perform logical fault finding on a non-functioning module:

1. First, ensure that a fault really exists. Check that the module is in the correct mode of operation and that no jacks are interrupting the signal flow at the insert points.

2. If in doubt, set up an adjacent, working module in exactly the same way for direct comparison.

3. Route the channel directly to MIX for monitoring. Using an oscillator set to approximately 1kHz, patch the signal into the channel Line Input.

4. Try bypassing large sections of the module circuitry, such as the Hi-pass filter and the Equalizer. If switching out a section causes the signal to reappear, the fault is located in that section.

5. To trace at the component level, remove the module and reconnect it via extender cables. This provides access to all parts of the module. You can then trace the signal through various stages using an oscilloscope, millivoltmeter, or high impedance headphones to find where the signal is lost or distorted.

1. Remove the 2 module retaining screws.

2. The module can now be carefully withdrawn from the console.

3. The ribbon cable will be exposed and may be detached from the module.

4. The module will still have some cables attached, but these are sufficiently long to allow the module to be completely withdrawn from the console.

Extender cables can then be plugged in for servicing. While the module can be plugged and unplugged with the power on, it is not recommended for the inexperienced as it is possible to bend connector pins.

OVU is normally adjusted to indicate a line level of +4dBu (1.228 volts). To align the meters:

1. Connect a millivoltmeter to the group output.

2. Route an oscillator set to 1kHz to the group outputs (e.g., 1-4).

3. Adjust the group output levels to read the required level on the millivoltmeter (e.g., +4dBu).

4. Adjust the VU drive pre-set on the drive card to indicate OVU on the VU meters.

5. Repeat for all other group meters and the Stereo mix meters.

Note that the peak LED will always indicate a level of 8dB above whatever the OVU level has been set to.

To replace the lamps:

1. First, remove the eight screws securing the PCB (on the stereo mix meters there are only 4 screws).

2. Remove the 6 screws that secure the sub-bracket (4 on the stereo mix meters).

3. The back of the meter is now accessible, and the lamps may be replaced.

It is recommended that both lamps be replaced even if only one has failed, as the remaining lamp will have been overstressed and its life substantially reduced.

If a power supply fault is suspected, follow these steps:

1. First, ensure it is the PSU at fault and not a short circuit in the console. Disconnect the PSU from the console and measure the voltage at the connector. A load should be provided to simulate normal console conditions (e.g., a 10 Ohm, 20 Watt resistor across each audio supply rail).

2. Measure the ripple and noise value of the supply rails. A value of at least -80dB (ref 0.775V) should be obtained on the audio rails.

3. If a fault is found, disconnect the mains supply and remove the cover. Check visually for obvious problems like a blown fuse or burnt components.

4. If nothing obvious is observed, reconnect the mains and measure the voltages across the various electrolytic smoothing capacitors. They should be as follows:

• Audio Supply C1: +26volts

• Audio Supply C5: -26volts

• +24volt Supply C9: +36volts

• Phantom Supply C13,C14: +59volts

Differences of +/-10% are acceptable. If satisfactory, the problem is in the regulator section. If not, check the bridge rectifier, smoothing capacitor, and transformer for failure.