Ashly 4.24C Crossover LCD Display, 19.7Hz 24dB-Lnkwtz, Input Long Time Delay For Remote Speakers

HPF or LPF Frequency

Channel 1-8

Operating Manual - PROTEA SYSTEM II 4.24C Crossover / System Processor

Input (Long) Time Delay For Remote Speakers

Speaker on

Main Stage

Secondary Speaker

200 ft from Main Stage

Same sound arrives at two different times.

Fix by delaying secondary speakers 177mS.

of the venue with direct line-of-sound to multiple loudspeakers. The solution is to delay the audio signal to the loudspeakers located beyond the main stage area, so that sound comes out of the distant loudspeakers at the exact time that sound from the main stage loudspeakers arrives. Within the Protea 4.24C, up to 682 milliseconds of time delay are available on each input channel, allowing secondary loudspeaker clusters to be time aligned with the primary speakers up to 771 feet (235m) away from the main stage area.

Output channels have time delay as

well, but much less than the inputs. This is	Output (Short) Time Delay
		For Driver Alignment
because output delay is best used to align dis-
crete drivers within a speaker cabinet or clus-				Example:	12 Inches
ter, normally quite close together. For example,
a typical three way speaker cluster would have					High - No Delay
low end, midrange, and high frequency drivers
all located near one another. The different driv-					Midrange Delay
ers for each frequency band are not necessar-
					12 Inches = 0. 9mS
ily the same physical depth with respect to the
front of the loudspeaker cluster, so there ex-
ists the problem of same signals (at the cross-					Low Delay
over points) arriving at the cluster "front" at					8 Inches = 0. 6mS
different times, creating undesirable wave in-
teraction and frequency cancellation. The so-
lution, again, is to slightly delay the signal to			Example:		8 Inches

the drivers closest to the cluster front. Using the location of the driver diaphragm farthest

back as a reference point, measure the distance to other drivers in the cluster, and set the output delay for each accordingly, with the driver diaphragm closest to the front getting the longest delay and the driver at the very back getting no output delay. Note: Although delay in the 4.24C is adjusted only by time, the corresponding dis- tance in both feet and meters is always shown as well.

4.6d Crossover (Xover)

Crossover functions on the Protea 4.24C are available only on the

eight output channels . Every channel's crossover consists of a high pass filter (HPF) and a low pass filter (LPF), along with the frequencies and filter types used. Each output's cross- over section is essentially a bandpass filter, making it necessary for the user to map out ahead of time which outputs frequencies and types accordingly. Note: determines the upper frequency limit.

Crossover LCD Display

Crossover			HPF and LPF
	CROSSOVER 1	HPF	Select
	19.7Hz 24dB-Lnkwtz		Slope and
			Response

will be used for the various frequency bands, and set the overlapping filter The HPF determines the lower frequendy limit of the signal, while the LPF

The frequency range for the high pass filter (HPF) is from 19.7Hz to 21.9kHz, with an option to turn the filter off at the low end of the frequency selection. The low pass filter (LPF) offers the same frequency range, with the "off" option at the high end of the frequency selection.

There are eleven types of filters available in the crossover section, each suited to a specific preference or purpose. The slope of each filter type is defined by the first characters in the filter type, 12dB, 18dB, 24dB, or 48dB per octave. The steeper the slope, the more abruptly the "edges" of the pass band will drop off. There is no best filter

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