Building Blocks THE SL501 MIC/LINE INPUT/OUTPUT CASSETTE The SL501 Mic/Line I/O cassette provides a choice between a microphone input or a line input. Source selection is accomplished by switches labelled MIC and LINE. A third switch provides phase reversal of the selected source. When the microphone input is selected, the signal is fed to a stepped rotary Mic Gain switch with a range of -80dB to -10dB in 5dB steps. This is followed by a continuously variable Trim pot with a range of ±10dB. When the line input is selected, its signal is fed directly to the Trim pot. 48v Phantom Powering for microphones is provided at the patchbay, along with switches to defeat this on individual channels. THE SL521 STEREO LINE INPUT/OUTPUT CASSETTE SL521 Stereo Line I/O cassette provides a stereo line input. Selection of either the MONO L or MONO R switch feeds the left or right signal of the selected source to the left and right channels of the input. This eliminates the need for special patching when a mono source is required. For example, if the input is normalled to a stereo VTR which happens to be loaded with a mono tape (audio on track 1), MONO L can be selected. Selection of both the MONO L and MONO R switches feeds the left + right signals of the selected source to both channels of the input. Individual Left and Right phase reversal switches are provided. INPUT BALANCE CONTROL The selected signals feed a gain Trim pot with a range of ±10dB, followed by a BALANCE pot which provides 6dB of left/right gain offset. This very important control allows the stereo balance of the incoming source to be fine-tuned as it enters the channel, ensuring that a properly adjusted stereo signal will be sent to any stereo auxiliary sends, the stereo insert points and the stereo channel direct output. THE SL505 DUAL LINE INPUT/OUTPUT CASSETTE The SL505 Dual Line I/O cassette provides a choice between two mono inputs. Source selection is determined by two switches labelled LINE 1 and LINE 2. A third switch provides phase reversal of the selected source. SL502 MONO 4 BAND EQUALISER CASSETTE Each band of the SL502 Mono Parametric Equaliser has a rotary gain control with a range of ±15dB. These controls have a centre-detent at their unity gain position. Continuously variable frequency control is provided on all four bands. The High-Mid and Low-Mid bands overlap to provide greater control in critical speech-intelligibility ranges. Each of these bands is also fitted with a switch labelled "HI Q". Normally, the mid-band curves have a 'Q' of 1 - operation of these switches changes that to a steeper 'Q' of 2.5. The High and Low frequency bands may be individually switched between shelving and peaking (bell) curves. The peaking curves have 'Q' of 1. An overall EQ In/Out switch with LED indicator is provided. The frequency ranges of each band are: HF Section: 3 KHz to 20 KHz HMF Section: 1 KHz to 6 KHz LMF Section: 200 Hz to 2.5 KHz LF Section: 35 Hz to 450 Hz THE SL522 STEREO 3 BAND EQUALISER CASSETTE Each band of the SL522 Stereo Parametric Equaliser has a precision-ganged stereo rotary gain control with a range of ±15dB. These controls have a centre-detent at their unity gain position. Continuously variable frequency control is provided on all three bands. The Mid-range band is fitted with a switch labelled "HI Q". Normally, the mid-band curve has a 'Q' of 1 - operation of this switch changes that to a steeper 'Q' of 2.5. The High and Low frequency bands may be individually switched between shelving and peaking (bell) curves. The peaking curves have a 'Q' of 1. HF Section: 1.5 KHz to 20 KHz MF Section: 400 Hz to 6 KHz LF Section: 35 Hz to 450 Hz THE SL510 MONO DYNAMICS CASSETTE The SL510 Mono Dynamics cassette is a full feature compressor/expander unit designed to give the operator critical control over all aspects of the signals dynamic range. The controls and their ranges are: RATIO: 9 Switched Ratios from: 1:1 to 100:1 THRESHOLD: Continuously Variable -20dB to +10dB RELEASE TIME: Continuously Variable 100ms to 4 sec ATTACK TIME: Normally Program Controlled 3ms to 30ms   FAST mode 3ms for 20dB of gain reduction The 2:1 expander may be switched to function as a 20:1 noise gate, providing useful noise reduction for a wide variety of programme material. The control ranges are: THRESHOLD: Continuously Variable -30dB to +10db RANGE: [EXP/Gate Mode] Continuously Variable 0dB to -60dB RELEASE TIME: Continuously Variable 100ms to 4 sec Hold Time: Continuously Variable 5ms to 2 sec before release activates GATE ATTACK TIME: Normal Mode 40dB in 1.5ms   FAST mode 40dB in 100 /µs The IN switch affects the entire cassette. The KEY switch allows patch access to the sidechain. The LINK switch connects the sidechain to that of the adjacent righthand Dynamics cassette for stereo working. Two 10 segment colour-coded LED displays indicate the amount of gain reduction introduced by each section's activity. THE SL520 STEREO COMPRESSOR/ LIMITER CASSETTE This cassette is optimised to provide stereo compression of composite programme material, followed by a peak limiter that is sufficiently fast to provide transient protection even on feeds to digital recorders. Although included here with Channel Elements, these cassettes are normally fitted in the Master Section of the console and are available via the patchbay. Two colour-coded LED displays indicate gain reduction, over a 20dB range in 1dB steps, introduced by the compressor and limiter. The controls and their ranges are: COMPRESSOR RATIO: 6 Switched Ratios from: 1:1 to 10:1 COMP THRESHOLD: 2dB Steps from: -20dB to +8dB COMP MAKEUP: Continuously Variable 0dB to +20dB COMP ATTACK TIME: 6 Switched Ratios from: 0.1ms to 30ms COMP RELEASE TIME: 6 Switched Ratios from: 0.1 S to 1.6 S Plus Automatic Mode           LIMITER THRESHOLD: 15 Switched positions from: 0dB to +16dB LIMIT ATTACK TIME: 2 Switched modes 0.5ms or 10 /µs LIMIT RELEASE TIME: 6 Switched modes 0.1 S to 1.0 S Plus Automatic Mode SL511 MONITOR/LINE I/O CASSETTE For consoles dedicated to post-production and re-mix applications, an SL511 Monitor/Line cassette can be fitted for up to 32 channels, one for each channel of the multitrack machine. Instead of Mic/Line or Dual Line input selection provided on the General Production Mono I/O cassettes, the SL511 provides a choice of one Line Input and two Multitrack Monitor Inputs, which are designated GROUP (Multitrack Send Monitor) and TAPE (Multitrack Return Monitor). The LINE input to the channel is selected using its local switch, and feeds its signal via a Trim pot with ±10dB of gain. The phase reverse switch operates only on this input. The GROUP and TAPE Monitor inputs may be selected using their local switches, or they may be selected on a master basis from the SL549 Multitrack Assign and Status Master cassette. The cassette provides a mix bus amplifier and balanced output driver for the send to the multitrack. The Group Trim control has a range of -30dB to +10dB with a detent at unity gain. The DIRECT switch bypasses the mix amp and routes a post channel fader signal to the Group output, which is usually normalled at the patch to the input of its same-numbered channel on the multitrack machine. A switchable insert point is normally post equaliser (if fitted); the PRE switch allows it to be placed before the equaliser. As it true of all SL 5000 M Series I/O cassettes, a switchable filter section is provided. The high pass filter has a range of 15Hz-350Hz with an 18dB/octave slope. The lowpass filter has a range of 3KHz-20KHz with a 12dB/octave slope. A hidden-til-lit display at the top of the cassette indicates the channel's assignment to any Audio Subgroups and Independent Main Outputs. Routing to the same-numbered channel on the multi-track is accomplished using the DIRECT button. Routing to any combination of multitrack channels is normally accomplished via an audio subgroup. If desired, an SL512 Multitrack Send cassette may be fitted to the channel, allowing the channel output to be directly assigned to any combination of multitrack groups. THE SL517 MULTITRACK SEND AND MONITOR CASSETTE Used in conjunction with an SL501 Mic/Line I/O or SL505 Dual Line I/O, this cassette creates a channel strip with an In-Line multitrack monitor section. At the top of the SL517, a hidden-til-lit display indicates assignments to the multitrack Groups. The odd/even Pan pot is automatically switched into the circuit when odd and even tracks are assigned. The Group output consists of a mix amp feeding a Trim control with a detent at unity gain. This is followed by the group output amp, which also accepts Tone and Slate signals. MONITOR SOURCE SELECTION The monitor section selects between two inputs. The GROUP monitor is normalled from the send to the multitrack, and the TAPE monitor is normalled from the multitrack return. The cassette normally monitors the send (GROUP), but can be switched to the return (TAPE) by pressing the local TAPE switch. Master GROUP/TAPE switching is provided on the SL549 Multitrack Assign and Status Master. If TAPE is selected and the multitrack is in Sync/Ready, the Monitor automatically switches to GROUP when the multitrack is switched to Record. Following the monitor switches is a 65mm P & G fader which feeds a stereo monitor bus via a left/right Pan pot. ON and AFL switches are provided. AFL may be configured to Solo In Place from the SL549 Multitrack Assign and Status Master. TRACK BOUNCING AND ADDITIONAL AUDO SUBGROUPING FUNCTIONS A switch on the SL517 cassette labelled "BNCE" feeds the post pan pot monitor fader signal to the central routing matrix, allowing easy track bouncing. A balanced pre-fader output of the monitor section may also be fed to a Line input of the channel's associated I/O cassette, enabling track bouncing with full channel facilities (EQ and Dynamics etc.) This provision also allows multitrack groups and channels to serve as additional audio subgroups.