APHEX CX-1 Compressor Expander Instruction Manual

APHEX CX-1 Compressor Expander

QUICK OPERATING GUIDE

COMPRESSOR FEATURES

• “Soft knee” or leveling amplifier characteristic comparable to LA-2A. * “Tube type” overload characteristics.
• Release time variable from 50 msec to 2.5 sec. (Tc).
• Threshold control works from -20 dbV to +20 dB V.

EXPANDER FEATURES

• Expansion depth control allows settings from 0 dB to 100 dB maximum gating (X depth).
• Expansion delay time from 50 msec to 2.5 sec. (Tx).
• Threshold control works from -45 dB V to +8 dB V.

METERING

• Internal metering: 10 segment bar graph displaying:
• Compression gain reduction
• Expansion gain reduction
• C + X gain reduction
• Output level
• External metering: optional vu meter connection terminals for traditional meter display.

CONTROLS

• Display select (compression or expansion)
• Compression in/out
• Compression threshold
• Compression release time
• Expansion in/out
• Expansion threshold
• Expansion delay time
• in/Out – control defeat
• Input gain
• Expansion depth

SPECIFICATIONS

• INPUT GAIN: Adjustable from -20 dB loss to +20 dB gain.
• INPUT LEVEL: Adjustable from -20 dB V to +40 dB V nominal.
• MAXIMUM OUTPUT: +30 dBm via Jensen nickel core transformer.
• MAXIMUM THD: Under steady state conditions: 0.10% (20 to 20 kHz.).
• MAXIMUM IMD: Under steady state conditions: 0.20% (SMPTE test).
• SLEW RATE OF MAIN SIGNAL PATH: Greater than 10 V/microsec.
• OUTPUT NOISE AT UNITY GAIN : -85 dBm (input shorted, 20 kHz BW).
• DIMENSIONS: Front Panel: 5.25 in. x 1.5 in. (13.3 cm. x 3.8 c,.) Depth: 6 in. (15.2 cm.)

COMPRESSOR- EXPANDER

CHECK OUT PROCEDURES

NECESSARY EQUIPMENT

• Distortion analyzer capable of +30dBm input
• A.C. Signal source
• Dual trace scope with X-Y capability
• Test Fixture: (female eage connector, wired to interface with test equipment.)
• Power Supply: + 16V @ . 2A
• Triangle or ramp wave source: (20V p-p)

INITIAL

Set Controls

• All buttons out
• Monet quite t2 – In (Pre) Position

Signal Pass Test
Generator at 2kHz +4đBm

• Adjust gain control to verify max unclipped output of +30 ₫Bm.
• Switch the signal source to 20 kHz. Observe waveform on CX-1 at unity.
• Adjust VU cal trimmer (R116) for eVU on LED display.

Expander Test

• Bypass, expand & X buttons in.
  • x depth – max (cw)
  • x threshold full CW
• Rotate the threshold to verify the gating action.
• While gated (off) rotate x depth. Verify the change in antenna-
• titateeth as web ty coated in turnoff time in several positions as Xthresh. is rapidly changed.
• Generator to +100Bm. Xthresh full CCW slowly decreases the generator level. CX should gate at +7 to +9 aBm.
• Mute generator x depth full CCW Set C-X meter trim (R240) to Fullon Verify meter goes off as depth –full CW

Noise Test

• a. Mute input
• b. Put CX-l in expand mode
• c. Rotate X depth full CW. Noise should measure 90dBm
• d. Slowly rotate X-depth CCW. Noise should rise to  – 83dBm with a worst-case peak value of  -820Bm just below full CCW.

Compressor Test
Generator on +4dBm, 2kHz bypass, Comp, C buttons in, others out.

• Comp three. Full CCW, verify no attenuation.
• As the knob is turned CW, verify signal attenuation, meter decline.
• Ctc at min (CCW). The signal should follow as Cth is quickly turned.
• Ctc at max (CW), the signal should slowly turn on as Cth is rotated quickly.

D.C. OFFSET ADJUSTMENTS

• Equipment – Triangle Wave ( ) Gen Dual trace scope:x-y capability  5mV sensitivity  +16V @ 2A power supply Noise filter

Set Controls

• Bypass and expand in others out Knobs – depth full. CW, gain = unity Xtc, Xthresh. = Full CCW Sidechains off (out)

Hookup – See drawing

• Generator at 20V P-P, 3Hz
  1. to scope Horiz. input IV scale, DC coupled
  2. to CX side chain, input, pin II
• CX input shorted
• CX output, pin 2 to scope vert input, 5mV scale ac coupled
• Observe scope trace and trim DC offset (R205) for minimum vertical deflection on scope.
• DC should remain below 8mV P-P.

CX-1 DC OFFSET NULL TEST SET-UP.

CX-1 DC SHIFT NULL EXPECTED SCOPE TRACES

COMPONENT LIST

RESISTORS

ADDENDUM FOR TRANSFORMERLESS CX-1

• R114 = 120K
• C110 = luf
• FB201 = 1500hm
• Top card output to pin 2 edge connector. Jumper pins 2 & 3 and 4 & 5 on edge connector.

COMPRESSOR/EXPANDER

Side Chain Switch

CX-1’s are equipped with a side chain source switch on P. C. Board # 1 which allows even greater versatility of the CX-1. The switch positions are:

• PRE: In this position the CX-1 is triggered from an internal audio signal, before the input gain pot. This is the normal mode of operation unless the CX-1 is installed in a “normally” type rack. (See note 1).
• POST: This position can be used when triggering’ is desired off signals lower than -40Bv. The threshold pots now’ follow the gain pot. Not used for most general applications.
• EXT: (External) – In this position the CX-1 can be triggered from any external low voltage including audio, between -40 and +8dBv. This position would be used when triggering the CX-1 from an equalizer or other outboard signal processing device, or when installed in a rack/patch bay that normals “Pre Out” to “Ext In” making the external keying input available at the patch bay.

NOTES:

1. The Aphex Systems 4B-1 is a “normalling” type rack. The switch must be in the Ext position to use the side chain access.
2. If building your rack system, the card edge terminals for the Ext functions are Pre Out = # 6, Post Out = # 7, Ext in = # 11.
3. Some earlier model CX-1s have a D. I. P. type switch instead of the slide switch. The settings are:

BLOCK DIAGRAM

CONNECTOR

1. CHASSIS GND
2. HI LEVEL OUT
3. LO LEVEL OUT
4. OUTPUT LOW SIDE
5. GND
6. PRE OUT
7. POST-OUT
8. GND
9. AUDIO IN
10. 11. EXT. SIDE CH. IN
11. +16V
12. GND
13. -16V
14. EXT. METER OUT

13340 Saticoy Street • North Hollywood, California 91605 • 818-765-2212 • TWX: 910-321-5762

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