Orban 2200 User Manual
OPTIMOD-FM 2200 |
OPERATION 3-1 |
Section 3
Operation
page contents
3-3 2200 Controls and Meters
3-5 Introduction to Processing
3-7 About the Processing Structures
3-7 Factory Programming Presets
3-9 Customizing the 2200’s Two-Band Sound
3-11 Two-Band Processing Control Details
3-19 Customizing The Protection Limiter Structure Sound
3-19 Protection/Limiting Control Details
3-21 2200 Screen Displays
Caution
The installation and servicing instructions in this manual are for use by qualified personnel only. To avoid electric shock do not perform any servicing other than that contained in the Operating Instructions unless you are qualified to do so. Refer all servicing to qualified service personnel.
3-2 OPERATION |
OPTIMOD-FM 2200 |
OPTIMOD-FM 2200 |
OPERATION 3-3 |
2200 Controls and Meters
2200 Front Panel
Screen Display labels the four soft key buttons and provides control setting information.
Screen Saver feature: The screen has a built-in screen saver that turns off the backlight after approximately one hour. The screen turns back on when any front panel control is touched. Note that buttons don’t perform their normal function when the screen is blank. Similarly, the control knob’s first turn is not read, until it stops for a second or so.
Contrast Button adjusts the optimum viewing angle of the screen display. Press this button to cycle through four contrast settings for the screen display.
Four Soft Key Buttons provide access to all 2200 functions and controls. The functions of the buttons change with each screen according to the labels at the bottom of each screen. Push a button:
To select options (always identified on the screen by all-capital-letter words surrounded by left and right vertical bars), press the button directly below the option.
To change a parameter setting (always identified by lower-case letters or numerals), hold down the button directly below the parameter setting, turn the control knob to scroll through choices, and release the button to set the parameter.
Control Knob is used for changing data in one of three methods.
To scroll through submenu choices: Presets (on Recall Preset screen), FULL CONTROL parameters (on Modify Processing FULL CONTROL screen) and 8 Remote Interfaces (on System Setup REMOTE INTERFACE screen).
To change a parameter setting, by simultaneously holding down a soft key. The parameters being changed take effect immediately, except for the following system level controls: MODE (on test screen), MODE (on Stereo Encoder screen), INPUT, AO PRE-E, DO PRE-E, DO RATE, DO SYNC and
XTLK TEST. The setting for these controls do not take effect until the soft key is released.
To adjust the LESS-MORE control. Adjusting this control changes the sound immediately.
Escape Button returns the user to the previous screen; pressing this button repeatedly will always return you to main screen, which shows the on-air preset name.
Recall Preset Button brings up a screen that displays the current on-air preset and next preset (which can be changed by turning the control knob). To put a different preset on-air, turn the control knob to find the preset desired, then press the
soft key.
When the button’s yellow LED is lit, the Recall Preset screen is displayed.
3-4 OPERATION |
OPTIMOD-FM 2200 |
Modify Processing Button brings up a screen to modify parameters for the current on-air preset. For Two-Band presets: LESS-MORE, EQ and FULL CONTROL. For the Protection preset, DRIVE and 30HzHPF.
When the button’s yellow LED is lit, the Modify Processing screen (or one of its submenus) is displayed.
System Setup Button brings up a screen to modify system settings (such as I/O levels). There are four System Setup submenus: I/O CALIB, STEREO ENCODER, RE-
MOTE INTERFACE, TEST.
When the button’s yellow LED is lit, the System Setup screen (or one of its submenus) is displayed.
HF Limiting LEDs light when the high-frequency content of audio is being limited by the very fast high-frequency limiters. These LEDs indicate when greater than 0.5dB HF limiting is occurring.
Gated LED indicates gate activity, lighting when the input audio falls below the threshold set by the gate threshold control (Modify Processing screen
control). When this happens, the compressor’s recovery time is drastically slowed to prevent noise rush-up during low-level passages.
Composite Meter is a 10-segment bargraph showing the stereo encoder’s composite output level before the composite level controls.
Function Button selects which of three functions are displayed in the Function meters: Enhance, L/R Input or L/R Output.
Function LEDs indicate which function is currently displayed by the Function meters: Enhance, L/R Input or L/R Output. Press the Function button to toggle between the three functions.
Function Meter indicates level of Enhance, L/R Channel Input or Output, as selected with Function button. The meters operate over a − 27dB to 0dB range. Input meters are referenced to clip level. Output meters are referenced to 100% modulation level. HF Enhance meter shows the active amount of enhancement activity. Since the HF Enhancement is program-dependent, it will vary with source material and the HF parameter. Note: HF Enhance is displayed only on the left-hand meter, below “HF.”
Stereo Encoder Screwdriver-Adjustable Controls
Orban supplies a special green-handled flat-blade screwdriver (Xcelite R3323) to adjust the stereo encoder controls.
Comp 1 sets the output level of Composite Output 1.
Comp 2 sets the output level of Composite Output 2.
OPTIMOD-FM 2200 |
OPERATION 3-5 |
Introduction to Processing
Some Audio Processing Concepts
Loudness is increased by reducing the peak-to-average ratio of the audio. If peaks are reduced, the average level can be increased within the permitted modulation limits. The effectiveness with which this can be accomplished without introducing objectionable side effects (such as clipping distortion) is the single best measure of audio processing effectiveness.
Compression reduces the difference in level between the soft and loud sounds to make more efficient use of permitted peak level limits, resulting in a subjective increase in the loudness of soft sounds. It cannot make loud sounds seem louder. Compression reduces dynamic range relatively slowly in a manner similar to riding the gain: limiting and clipping, on the other hand, reduce the short-term peak-to-average ratio of the audio.
Limiting increases audio density. Increasing density can make loud sounds seem louder, but can also result in an unattractive busier, flatter, or denser sound. It is important to be aware of the many negative subjective side effects of excessive density when setting controls that affect the density of the processed sound.
Clipping sharp peaks does not produce any audible side effects when done moderately. Excessive clipping will be perceived as audible distortion.
Distortion in Processing
In a competently-designed processor, distortion occurs only when the processor is clipping peaks to prevent the audio from exceeding the peak modulation limits of the transmission channel. The less clipping that occurs, the less likely that the listener will hear distortion. However, to reduce clipping, you must decrease the drive level to the clipper, which causes the average level (and thus, the loudness) to decrease proportionally.
The FM pre-emphasis curve introduces further complications. Pre-emphasis boosts the treble at 6dB/octave starting at 2.1kHz (for 75 s countries) or 3.2kHz (for 50 s countries). This reduces the headroom available at high frequencies, and makes it difficult to achieve a bright sound. This is because bright sound requires considerable high-frequency power to appear at the output of the receiver’s de-emphasis filter, and thus requires a very large amount of high-frequency power to be transmitted so that a sufficient amount will survive the de-emphasis process.
Without very artful processing, the pre-emphasis will radically increase the level of the peaks and force you to decrease the average level proportionally. Orban’s high-frequency limiting and distortion-canceling clipping systems greatly ease this trade-off, but cannot entirely eliminate it. Therefore, you can only increase brightness by reducing average modulation (loudness) — unless you accept the increased distortion caused by driving the final clippers harder.
3-6 OPERATION |
OPTIMOD-FM 2200 |
Loudness, Brightness and Distortion.
In processing, there is a direct trade-off between loudness, brightness, and distortion. You can improve one only at the expense of one or both of the other two. Thanks to Orban’s psychoacoustically-optimized designs, this is less true of Orban processors than of any others. Nevertheless, all intelligent processor designers must acknowledge and work within the laws of physics as they apply to this trade-off.
Perhaps the most difficult part of adjusting a processor is determining the best trade-off for a given situation. We feel that it is usually wiser to give up ultimate loudness to achieve brightness and low distortion. A listener can compensate for loudness by simply adjusting the volume control. But there is nothing the listener can do to make an excessively-clipped signal sound clean again, or to undo the effects of excessive high-frequency limiting.
If processing for high quality is done carefully, the sound will also be excellent on small radios. Although such a signal might fall slightly short of ultimate loudness, it will tend to compensate with an openness, depth, and punch (even on small radios) that cannot be obtained when the signal is excessively squashed.
If women form a significant portion of the station’s audience, bear in mind that women are more sensitive to distortion and listening fatigue than men. In any format requiring longterm listening to achieve market share, great care should be taken not to alienate women by excessive stridency, harshness, or distortion.
OPTIMOD-FM — from Bach to rock
OPTIMOD-FM can be adjusted so that the output sounds as close as possible to the input at all times (using the Protection Limiter Structure), or so that it sounds open but more uniform in frequency balance (and often more dramatic) than the input (using the Two-Band Structure). The loudness/brightness/distortion trade-off explained above applies to any of these setups.
You will achieve best results if Engineering, Programming, and Management go out of their way to communicate and cooperate with each other. It is important that Engineering understand the sound that Programming desires, and that Management fully understand the trade-offs involved in optimizing one parameter (such as loudness) at the expense of others (such as brightness, distortion, or excessive density).
Never lose sight of the fact that, while the listener can easily control loudness, he or she cannot undo excessive high-frequency limiting or make a distorted signal clean again. If such excessive processing is permitted to audibly degrade the sound of the original program material, the signal is irrevocably contaminated and the original quality can never be recovered.
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