Solid State Logic 82S6XL010D Operation, Compressor Controls, Side Chain Adjust Section

Installation and Operation

4.0 Operation

The XLogic Multichannel Compressor unit is a 2U rack-mounting six-channel compressor designed to provide extremely flexible control over a 5.1 channel mix, or to be used as two separate compressors when working on stereo material. The compressor design is very similar to that found in the XL 9000 console centre section, but with additional controls to provide the flexibility that modern 5.1 productions require. The signal path is balanced and DC coupled through out: this ensures extended bandwidth, low noise and low distortion.

5.1mixing presents a number of challenges to the engineer that are not present when working in stereo. This is essentially because the signal content can vary hugely between speakers - both in level and frequency content – unlike stereo material where the two channels are normally similar in both level and content. This presents a number of potential problems including:

•The LFE channel will almost certainly require different attack and release times and different thresholds from the other channels.

•Depending on the material you may or may not want some channels to be compressed.

•Conversely you may want some channels to be compressed but not to contribute to the overall compression.

•You may want channels to have different thresholds.

•With five speakers it is possible have signals panned so that they are the loudest signal in the room but not the loudest signal in any one speaker.

The XLogic Multichannel Compressor is designed to give the engineer a flexible but easy to use set of tools to deal with all these potential problems – and hopefully those we haven’t thought of yet.

4.1Compressor Controls

The compressor sidechain controls
are straight forward and hopefully				METER						MAIN/STEREO A
require	little	explanation.	The	8	12		THRESHOLD		ATTACK - mS		RATIO		5	RELEASE - S		MAKE-UP
								.3	1	10	2	4		.2	1.6
										3	3			.4	.8
ATTACK, RELEASE and RATIO				4		16		.1			30 1.5		10	1		AUTO
				0	dB		IN									0
						20
controls are six position switches:				COMPRESSION
							-20	+20
the THRESHOLD and MAKEUP										LFE/STEREO B
GAIN	controls	are continuously					THRESHOLD		ATTACK - mS		RATIO			RELEASE - S		MAKE-UP
									1	3	3	4		.4	.8
variable.							IN	.3		10	2		5	.2	1.6
					LFE/											0
								.1			30 1.5		10	1		AUTO
					ST B

The compression meter at the left
of the unit normally displays gain	-20 +20
reduction for the Main (upper)

compressor. Pressing the LFE/STB switch shows the gain reduction for the LFE (lower) compressor.

4.2Side Chain Adjust Section

The side chain adjust section is the key to the operation of the XLogic Multichannel Compressor. It provides very flexible control of the compressor side chain.

					S-CHAIN TRIM controls – These allow the contribution of their
	SIDE CHAIN ADJUST				respective channels to the side chain to be adjusted - effectively
					allowing different thresholds to be set for each input. They are
LEFT/RIGHT		C		CENTRE
					indented at the ‘2 o'clock’ position (which is marked ‘0’) to allow
0 L			R	0
				ISO	the trims to be easily set to the same level. When fully clockwise
+10		LFE		+10
					they increase the side chain level by 10dB – effectively reducing
S-CHAIN TRIM	LS		RS	S-CHAIN TRIM
		MAX
					the threshold on that channel by 10dB. Turning a trim control
LFE				SURROUND	fully anti-clockwise removes that input from the side chain
0				0
LINK	LFE	LFE		ISO	completely.
		0DB
+10				+10	An example may help: imagine the mix you are working on has
S-CHAIN TRIM				S-CHAIN TRIM
					a number of loud sound effects in the surround channels. You
					want the surround channels to follow the same compression as

the front channels, but don’t want the sound effects to compress the front channels. To achieve this simply turn the side chain trim control on the Surround channels anti-clockwise.

Page 7