Solid State Logic X-Rack E Series Connection, Operation, ‘Brown Knob’ EQ, ‘Black Knob’ EQ

X-Rack E Series EQ Module

K. E Series EQ Module

K.1 Connection

IN

-10dBV

+4dBu

OUT

The module input and output gains can be set to operate at a nominal level of either +4dBu or –10dBV, using a switch on the connector panel. To select the appropriate level for the equipment you are connecting to, please check the operating manual for your mixer or DAW. The switch should be released for +4dBu operation: push it in for –10dBV operation.

K.2

K.2.1

K.2.2

Operation

The X-Rack E Series EQ module is a re-implementation of two of the classic SSL EQ circuits. The module defaults to the original ‘Brown Knob’ circuit that was standard on all early production E Series consoles but can be switched to emulate the later ‘Black Knob’ circuit.

The BLK button	1 switches the module from the default ‘Brown Knob’ EQ to
‘Black Knob’ EQ.	switches the entire section in and out of circuit.
The IN button 2

‘Brown Knob’ EQ

With the BLK button out, the two parametric mid-band sections feature SSL’s classic logarithmically symmetric design that ensures that the ±3dB up/down points retain the same musical interval from the centre frequency regardless of frequency and amplitude settings. The two shelving sections are traditional 6dB/octave designs with an option for a fixed Q parametric response (Bell). The ‘02’ EQ, to give it its correct name, was used on countless recordings and mixes in the early eighties.

‘Black Knob’ EQ

In 1983 a new ‘242’ EQ circuit was developed in conjunction with the legendary George Martin for the first SSL console to be installed in AIR studios. The ‘Black Knob’ EQ, as it became known, featured enhanced cut and boost ranges (±18dB instead of ±15dB) together with a different control law and a steeper 18dB/octave high pass filter for tighter control of low frequencies. It is this design which is retained today as the ‘E Series’ EQ option of the AWS 900 and Duality consoles. It is also to be found in use in the X-Rack XR625 EQ module which features this design alongside an implementation of the ‘G Series’ EQ.

XR425
SEL
HF	dB
				BELL
-		+		KHz
			5	10
HMF	dB		2	14
			1.5	16

-		+		KHz
			1.5	4.5
	Q	.8		6
			.6	7
					1
				BLK
LMF	dB			IN	2
				KHz
-		+
			.8	1.5
	Q	.3		2.0
			.2	2.5
				Hz
				300
LF	dB		30	450
-		+		BELL

Page K-1