The Patchbay Patchbay Allows easy routing into and between... - PowerPoint PPT Presentation

The Patchbay

Patchbay Allows easy routing into and between... Studio and Control room Console Inputs Console and Multitrack Recorder Console and outboard gear Di ff erent studios in one facility

Patchbay Plug Types Balanced XLR - large - Mic panels 1/4” TRS - common, o ff the shelf TT -mini (Bantam/TT) - most common Can fit a lot of patch points in a small space Unbalanced 1/4” TR RCA

Rear Attachment Type D-Sub - DB25 Multi-pin connector Punch Block Hardwired - Soldered Elco/EDAC - 8-32 channels Mirrored

Patch Jack Configurations 4 TYPES Parallel Half-Normalled Normalled also called Full Normal Open

Parallel I/O always connected Allows you to take the signal at input or output

Half-Normalled 1 No plugs = I/O connected Patch out top = I/O connected 2 Split the signal Patch out bottom = I/O Broken 3 Patch out both = I/O Broken 4

Half-Normalled

Normalled No Plugs = I/O Connected 1 Patch out Top = Broken I/O 2 Patch In bottom = Broken I/O 3 Patch Out both = Broken I/O 4

Normalled

Open I/O NEVER connected

Other considerations Mults One Input --> Multiple Outputs Nor/Half Switching Oxidation and Dust Digital Patchbays

Metering Introduction Two major types of Analog meters VU Meter Peak Program Meter (PPM)

The VU Meter • “Volume Unit” • Volt Meter • Simulates the way we hear • Reads the RMS values of the signal • Ballistics • 300ms response and fallback time • Ignores instantaneous peaks or high transient signals • Good for seeing average signal level

The VU Meter Calibrated to a standard dB like scale. 0 VU = +4 dBu for a steady state sine wave (1.23V rms) +8 dBu in broadcast and telephone equipment. (0 VU = 1.95 V) Digital System we choose Cal. point 0 VU = -20, -18, -16, -14, -12 dB FS

VU Meter Show RMS values Crest Factor - di ff erence b/n RMS and peak level Sine wave has 3dB peak above RMS (Crest Factor) Voice and Music has typical Crest Factor 10-12 dB Easy for VU meter to miss transients

Peak Meters Peak Program Meter Shows the instantaneous level of input signal Doesn’t correlate with perceived loudness 10ms rise time - 3sec fallback time ~ 4db space between markings BBC STYLE PPM

Dorrough Loudness Meter Shows Peak and RMS level values “Spectral Density” Average indicator Headroom

Digital Level Meters Based on Digital Full Scale Bit depth determines resolution and dynamic range Relative Scales - depends on reference Peak Holds Multi Scale

Oscilloscope Patterns Stereo Metering Visual Imaging of Stereo Image Stereo Width Phase Problems Lissajous Patterns

Spectrograph Spectral Graph Frequency vs. Amplitude Varied Resolution

Spectrogram Time vs. Frequency vs. Amplitude Spectral Density Harmonic Structure Audio prints