User manual XTA SIDD PC SOFTWARE V2

[. . . ] Contents CONTENTS THANKS INTRODUCTION INSTALLATION STARTING THE SOFTWARE CONNECTING UNITS TO THE COMPUTER Using Midi. . . Using RS485. . . 2 4 4 5 7 8 8 8 8 TYPICAL INTERFACE SET-UPS RS232 Connection (Single Unit) RS232 Connection (Multiple Units) RS485 Connection Midi Connection 9 9 9 10 10 SETTING UP COMMUNICATIONS AND GOING ON-LINE BREAKDOWN OF THE MAIN SCREEN. MENU BAR AND TOOL BAR SUMMARY GUIDES SYSTEM BAR AND SYSTEM TOOLBAR FUNCTION MODES ­ EXPERT/NORMAL/BASIC. . . MODIFIYING THE USER VIEWS CHANGING THE SIZE OF THE EDIT WINDOWS ANALOGUE METERING MODE MODIFYING THE UNIT'S CONFIGURATION Configuring the Computer and Software Going `On-line' 11 13 14 15 16 19 20 21 22 11 12 WHAT IS DYNAMIC EQ? [. . . ] In this example, channel A is above the threshold, and channel B is below. SiDD PC Software Version 2. 00 Page 39 Indication of Clipping The Input to a Module Before exploring editing any further, it's worth noting that whilst SiDD possesses very high headroom due to the 40-bit accumulators used for all calculations (as opposed to more usual 24 or 32 bit), it is still possible to reach an overload state internally. Even if the input to the unit appears to be relatively low according to the input meter, if input gain has been added and there is a lot of boosted EQ, the signal level within the unit can be running at a very high level. This will not always be apparent, especially in the case of the dynamic EQ module where a large amount of signal amplification can be introduced, but only on peaks (which by their nature are higher than the usual signal level). If the input to a module is too high, the in/out transfer function graph will flash the message `Overdrive' as shown below. Reduce the level from the offending module to until the warning disappears, or audible distortion will occur. Note that this message refers to the input of the module, so the level needs to be reduced `upstream' from the module displaying the message. The table below outlines possible scenarios. Overload Condition Input meter clipping (in the red) Dynamic EQ is being overdriven Gate or Expander is being overdriven Compressor is being overdriven Limiter is being overdriven Output meter clipping (in the red) Possible Cause Actual input level to the unit is too high Too much input EQ, or input gain too high. Also, ADT level may be too high4 or harmonics generator level(s) Dynamic EQ is applying too much boost. Either Input section is running too hot, or DEQ is running too hot Input section is running too hot, DEQ is running too hot, or Compressor makeup gain too high. Any previous condition, or output gain too high Possible Action Reduce the direct feed to the unit itself (adjusting the input gain control will not work) Reduce EQ boost, input gain, ADT level, or harmonics level Set DEQ threshold higher or reduce the `Max Gain' parameter if the threshold must remain fixed See DEQ action and Gate/Expander action See DEQ action and Gate/Expander action. Lower compressor threshold, or turn down makeup gain if threshold must remain fixed. Check all above actions or turn down output gain 4 Page 40 Only applicable in ADT mode SiDD PC Software Version 2. 00 Editing Parameters on the Dynamic Eq Window Having explained in detail how the dynamic EQ module works, adjusting the parameters is very straightforward. The threshold may be adjusted by either nudging the value using the arrows, or dragging it up and down directly on the in-out transfer function curve. Remember that to change the Quadrant (Operating mode), the ratio must first be set to 1:1. Attack time covers the range 30uS up to 2. 0 seconds. Note that the software will not allow release times to be less than attack times, due to the likely `parameter abuse' involved and subsequent poor performance. Adjusting the filter can again be accomplished by either nudging the frequency with the button or directly dragging the centre frequency, denoted by the red square, along the frequency response curve. Note that, unlike the EQ or sidechain frequency response curves, this square will be fixed in its vertical position, as the gain is the parameter being adjusted dynamically. To adjust the `Q' (or bandwidth) of the filter , use the nudge buttons beside the readout or, using the mouse, select the node and, holding the left mouse button down, move the scroll wheel. 5 Holding down `Shift' while moving the scroll wheel locks the frequency of the filter, making adjustment of the `Q' easier. 5 SiDD PC Software Version 2. 00 An `intellipoint' type mouse is required for this operation. Page 41 Noise Gate Know-how Most engineers know the principle reason for using a noise gate ­ to shut off the output of some device that, in the absence of the desired output signal, produces (or passes on) an undesirable level of background noise. The behaviour of the noise gate is controlled by adjusting, principally, its threshold. This sets the point at which the level of the desirable signal is deemed quiet enough to turn it off, thereby cutting off all the background noise as well. Considering the diagram shown here, the desired signal would be the high level burst and, in between, low level noise. [. . . ] This type of limiting is known as program limiting and is designed to control the average signal level. SiDD PC Software Version 2. 00 Page 67 Another limiting method is known as peak limiting and is characterised by the limiter having very a fast attack time (<10mS) and relatively fast release time (generally about 4 times the attack). This method is designed to prevent any excursion above the threshold (and so into the over-range region), and to recover from the gain reduction as fast as is musically possible. Consider the familiar signal burst diagram below, where region 2 represents the program material that has gone over the limiter threshold. In extreme cases, the limiter could be required to react instantaneously to the over-range condition, and prevent any overshoot. [. . . ]