Patch Bay

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• Purpose of a patch bay: To send audio signals from any audio source to any audio destination. (It has nothing to do with video signals, although it does deal with the sound accompanying video sources, such as from laserdisks or SVHS tapes.)

   

• Composition: One bank of an audio patch bay consists of two corresponding rows. The jacks in the top row are all outputs, and the bottom row jacks are all inputs.

   

• In our patch bay the 1st and 2nd rows make up one bank of corresponding jacks, and the 3rd and 4th rows provide another bank of paired jacks. (See diagram.)

   

• Normals: Many output-to-input connections are used normally. For ordinary use, it would be unsightly as well as inconvenient to connect them with patch cables. Therefore they have been connected with internal wires, or "normalled." "Normals" are the default connections ordinarily used. Not every jack is normalled, but those which are normalled always constitute a corresponding pair of jacks at the same position in a 52-Point bank. For example, output jack 101 is normalled to input jack 201, but it would never be normalled to 102, 202, 301, or 402.

   

• Multiple sends: A cable inserted into an output jack (top row; i.e., 1xx or 3xx) does not break any normal connection that output might have. One can send audio from a single source to multiple destinations. (We are not promoting "multiple sins.")

   

• Single ins: A cable inserted into an input jack (lower row; i.e., 2xx or 4xx) breaks any normal connection to that input. In other words, an input jack can receive audio signals from only one source at a time.

   

• Example: If a show tape comes with 2-channel audio on the first two tracks, patch 105 and 106 (ADAT outputs; see diagram) to 207 and 208 (mixer inputs; see diagram). This is a case of multiple sends, in that the same left-right signals will go to both the front speakers (normal sends through mixer channels 205 and 206) and to the rear speakers (non-normal sends through mixer channels 207 and 208).

   

• Application: If the show master tape does not have the dialog on the 5th track, then we would patch it to 209 (the mixer input corresponding to our 5th track) in order to make a new master tape appropriate for our set-up.

   

• Test yourself: One of the most common patches we will make is to connect 301 to 403 and 302 to 404. Study the following diagram to guess why.¹

   

• More Applications:
  • To record a concert, patch mixer outputs from mics, DI boxes, reverb, etc., to RD-8 B inputs (see Patch Bay diagram; the B or below deck is the Record deck).
  • To play a tape in the RD-8 B deck (this is unusual), patch to mixer inputs.
  • Soundtrack production requires patching between the A and B ADAT decks.

   

• Lack of normals: Some jacks have no normals (e.g., 309-316), since their destinations or sources are quite varied. Often normals between these corresponding pairs would send signals to themselves, or set up feedback loops. So jack pairs not normalled are that way for good reason, and should not be patched.

   

• Spare jacks: Some jacks are not used at all. These are shaded in the Patch Bay diagrams.

   

• Classification of jacks:
  • 1xx row Device outputs
  • 101-104 Microphone jacks
  • 105-111 RD-8 A outputs
  • 113 RD-8 A; SMPTE time-code output
  • 115-116 Lexicon reverb outputs
  • 117-118 Switcher outputs
  • 119-120 Cassette Deck outputs
  • 121-122 CD Player outputs
  • 123-124 Direct Boxes A & B
  • 125-126 Not assigned

     

  • 2xx row Mixer inputs
  • 201-204 Microphone signal inputs (weak signal strength²)
  • 205-222 Line inputs from ADAT, Switcher, Cassette, CD, and Direct Boxes

     

  • 301-308 Mixer outputs to 4xx bank
  • 301-304 Mixer Subgroup outputs (to four speakers, from white faders on mixer)
  • 305-308 Mixer Auxiliary outputs (controlled by 4 rows of Auxiliary knobs on mixer)
  • 305 Subwoofer output
  • 306 Dialog output
  • 307 Lexicon reverb output
  • 308 Hearing enhancement output
  • 309-316 RD8 B outputs (not normalled)
  • 317-318 Laserdisk A outputs
  • 319-320 Laserdisk B outputs
  • 321-322 SVHS outputs to Switcher channel #6
  • 324-326 SMPTE Time Code outputs

     

  • 401-406 Inputs to equalizers, amplifiers, and speakers
  • 407 Lexicon reverb input
  • 408 Hearing enhancement input
  • 409-416 RD-8 B inputs
  • 417-418 Laserdisk A inputs
  • 419-420 Laserdisk B inputs
  • 421-422 Switcher #6 inputs
  • 424-426 SMPTE Time Code inputs

¹ That's right: This patch converts stereo left-right two-channel sound (from any source) into a stereo pair of two-channel sound, left-right both front and back. The normal send 301 to 401 sends audio to the front left speaker, the non-normal send 301 to 403 sends audio to the rear left speaker. Similarly, the normal send 302 to 402 sends audio to the front right speaker, the non-normal send 302 to 404 sends audio to the rear right speaker. (Back)

² Line inputs are a stronger, hotter signal strength than mic signals. Severe distortion would result from sending a line signal (e.g., cassette or ADAT) into a mic signal input. Don't do it! Nor are line signal inputs sensitive enough for mic signals. Lines and mics don't mix! (Back)

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