StudioTech 233 manual Advanced Operation, Adjusting the Line Input Trim Pots

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one of the talkback outputs is active. The level control on the far right adjusts the side-tone level. When the sidetone level control is in its fully counterclockwise posi- tion the sidetone signal will always be fully muted.

Astute readers will realize that sidetone au- dio can also be provided from the intercom cue sources during Model 233 talkback to intercom activity. This “passive” sidetone is created in the intercom interface’s ana- log talk/listen hybrid sidetone (null) circuit. Trim pots allow the intercom sidetone level to be adjusted over a limited range. To get maximum performance when either or both intercom channels are used as a cue source one simple calibration process may need to be performed. This involves ad- justing the sidetone (null) trim pots to their fully counterclockwise positions, providing minimum sidetone level. This will reduce the level “build up” that would occur when both the main and the intercom sidetone audio signals are sent to the headphone output. The goal is for the sidetone level to remain as constant as possible, no matter what function—main output, talkback-to- line-level-output, or talkback-to-intercom— is active.

–12 dBV to +6 dBu can be effectively used as cue sources. Unfortunately, there are no definitive rules regarding how best to adjust the trim pots, but some suggestions may prove to be valuable. Depending on how the line inputs are utilized, the trim pots can be used to either adjust the absolute level of each line input signal, or to ad- just the relative level of the signals when compared to other sources. The following examples may provide some clarification.

Let’s begin with an application that has a stereo cue source connected to the line inputs. The cue source selection switches are configured to create a stereo head- phone output with line input 1 assigned

to the left channel and line input 2 assigned to the right channel. Begin the trim pot adjustment process by moving the user level controls (located on the front panel) to their detent (50% of rotation) positions. Then, with the stereo cue source provid- ing signal at its normal level, adjust the trim pots to provide a comfortable level

Advanced

Operation

Adjusting the Line Input Trim Pots

As has been previously mentioned, associ- ated with the two line inputs are trim pots that allow the input levels to be adjusted. The two trim pots are accessible by way of round openings in the bottom of the Model 233’s enclosure. By adjusting these trim pots, signals with a nominal signal level of

Figure23.Bottomview showing line input and talkback-to-intercom sidetone trim pots

Model 233 User Guide

Issue 1, September 2007

Studio Technologies, Inc.

Page 33

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Contents User Guide This page intentionally left blank Table of Contents Issue 1, September Model 233 User Guide Introduction What This User Guide CoversSystem Overview Microphone Input System FeaturesMain Output Talkback FunctionsUser Controls and Status Indicators Dynamic Range ControlFlexibility Sidetone Cue SourcesHeadphone Output Intercom Interface Power SourcesAudio Quality and Protection Auxiliary RelayConnectors ConfigurationAdditional Connector Locations Multi-Pin Headset ConnectorsInstallation and Setup OptionsSystem Components Headphone Output Line-Level Talkback Outputs Line Inputs External Power Input Pushbutton Labeling ConfigurationMicrophone Preamplifier Gain Microphone Preamplifier Gain and Phantom PowerHeadphone Source Selection Phantom Power On/OffLeft and right channel headphone source selection settings Headphone output mode settings Headphone Output ModeOperating Modes Main Output Button ModeTalkback 1 Button Mode Talkback 2 Button ModeTalkback 1 Button Function Sidetone Mode Talkback 2 Button FunctionMain Output Source Dual-Channel or Stereo Mode Reverse Left/Right ModeHeadphone Output Operating Modes Main Button Mode Minimum Level ModeSystem Mode Relay ModeTalkback 2 to Intercom Function Mode Talkback 1 to Intercom Function ModeOperation ConclusionPushbutton Switches and Status LEDs Main Output Button and LED IndicatorsMain Output Button Modes Talkback 2 Button and LED Indicator Talkback 1 Button and LED IndicatorTalkback 1 Button Modes Talkback Output 2 Button ModesLevel/Balance Mode Level/Level ModeSidetone Operation Monaural Headphone Output Level Control OperationAdvanced Operation Adjusting the Line Input Trim PotsIntercom Interface Sidetone Adjustment Technical NotesGrounding and Shielding Intercom Audio Levels Intercom Channel CrosstalkConnecting an IFB Circuit External Power Sources Phantom PowerSymptoms of Insufficient Power Additional Connectors LED ColorsTravel Case Issue 1, September Model 233 User Guide Pushbutton Backlighting P18 Remote Control/Tally ConnectionsP19 Compressor CircuitGeneral Audio SpecificationsAppendix a
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