STUDIO ELECTRONICS C2s DUAL COMPRESSOR/LIMITER

PRELIMINARY INFORMATION: 8-03-02


THE STUDIO ELECTRONICS C2s IS AN F.E.T. COMPRESSOR/LIMITER BASED ON THE UREI® 1176, WITH SIGNIFICANT DESIGN CHANGES AND MODIFICATIONS. INSTEAD OF THE CLASS AB PUSH-PULL OUTPUT STAGE, FOUND IN THE LATER 'F' SERIES 1176, A NEVE® 1272 TYPE CLASS A OUTPUT STAGE IS USED, INCORPORATING A SOWTER® TRANSFORMER BUILT TO 1272 SPECS. THIS IS SIMILAR TO EARLIER RELEASES OF THE 1176, RESULTING IN A SLIGHTLY DIFFERENT (READ BETTER) SOUND THAN THE LATER UNITS. OUR C2s's OUTPUT STAGE 'SYMMETRY' POT (R36) CAN BE ADJUSTED TO DELIBERATELY CLIP ASYMMETRICALLY; A WELL-KNOWN 1272 TRICK ADDING SECOND HARMONIC DISTORTION, WHICH SOME USERS FIND QUITE PLEASING. THIS ADJUSTMENT IS FACTORY DETERMINED FOR MAXIMUM HEADROOM BEFORE CLIPPING: MORE THAN +27DBM! ANOTHER REFINED DEPARTURE IS OUR UTILIZATION OF A JENSEN® TYPE (NOW BUILT BY REICHENBACH®) INPUT TRANSFORMER - ATTENUATOR MOVED TO THE 'SECONDARY'. THIS REDUCES DISTORTION AND NOISE BY INSURING THAT THE 'PRIMARY' IS ALWAYS FULLY DRIVEN. WITH PRECISION METAL FILM RESISTORS, GOLD XLRS, GOLD SWITCH CONTACTS, GOLD INTERNAL CONNECTIONS AND PREMIUM QUALITY CARBON AND CONDUCTIVE PLASTIC POTENTIOMETERS USED THROUGHOUT, A NOTABLY LOWER NOISE THAN IS USUALLY ASSOCIATED WITH VINTAGE UNITS AND AN IMPROVEMENT IN MATCHING BETWEEN THE TWO CHANNELS IS REALIZED. FURTHERMORE, WE'VE INCORPORATED THE MUCH-USED TECHNIQUE OF DEPRESSING ALL FOUR RATIO SELECT BUTTONS ON THE ORIGINAL 1176: THIS 'FEATURE' IS DUPLICATED EXACTLY IN THE “SQUASH” POSITION OF THE C2s's "RATIO" SELECTOR.

LASTLY, THE C2s INCORPORATES TWO DEDICATED L.E.D. METERS WITH PPM BALLISTICS. FOR THE FIRST TIME, IT IS POSSIBLE TO SIMULTANEOUSLY ACCURATELY JUDGE GAIN REDUCTION AND OUTPUT LEVEL, EVEN WITH VERY PERCUSSIVE MATERIAL. THE ORIGINAL 1176 FEATURED A VU METER THAT COULD ONLY BE SWITCHED BETWEEN INPUT, OUTPUT AND GAIN REDUCTION; BECAUSE OF THE SLUGGISH NATURE OF SAID METER, IT WAS NEXT TO USELESS FOR DETECTING ANY FAST MOVING SIGNALS AND TRANSIENTS.

THE C2s HAS UNDERGONE MORE THAN 10 MONTHS OF PAINSTAKING DESIGN AND RIGOROUS TESTING SO WE AT STUDIO ELECTRONICS ARE CONFIDANT IT WILL PROVE A PARTICULARLY PRODUCTIVE TOOL FOR 'TRACKING' AND 'MIXDOWN'. ADDITIONALLY WE'VE DISCOVERED THAT THIS DESIGN IS CAPABLE OF EXTREME AMOUNTS OF COMPRESSION AND LIMITING, BUT WITHOUT THE 'SQUEEZING' AND 'DULLING' THAT MORE MODERN DESIGNS USUALLY EXHIBIT. INDEED, SIGNALS PROCESSED BY THE C2s ACTUALLY SOUND BRIGHTER AND MORE 'PRESENT' AFTER COMPRESSION AND LIMITING - TREMENDOUSLY HELPFUL IN BRINGING LEAD INSTRUMENTS AND VOCALS CLEANLY TO THE FRONT OF YOUR MIX. WE HOPE THE CASWELL AUDIO SERIES C2s WILL PROVE EQUALLY SATISFYING IN YOUR PROVINCE OF INSPIRATION.

QUICK START GUIDE


'POWER UP' THE UNIT WITH “BYPASS” SWITCHES DOWN. THIS IS A TRUE RELAY BYPASS AND WILL PREVENT ANY 'POWERUP' TRANSIENTS. TRANSLATION: THE UNIT CAN BE CONNECTED BUT NOT POWERED AND STILL PASS SIGNAL.

ON THE REAR PANEL ARE FOUND THE "INPUT" AND "OUTPUT" JACKS (BOTH KINDS!) AND TWO SWITCHES. "INPUT GROUND" SHOULD USUALLY BE LIFTED IN BALANCED SYSTEMS (SEE JENSEN TRANSFORMERS WEB SITE). USE WHICHEVER POSITION YIELDS THE LEAST HUM. THE “TERMINATE” SWITCH PLACES A LOAD RESISTOR ACROSS THE OUTPUT TRANSFORMER, WHICH REDUCES 'OVERSHOOT' IF THE NEXT PIECE OF GEAR IN THE CHAIN IS A MODERN UNIT WITH BRIDGING INPUTS. HOWEVER, 'OVERSHOOT' USUALLY RESULTS IN INCREASED 'BRIGHTNESS', SO SET THIS TO TASTE. IF THE FOLLOWING DEVICE IS A VINTAGE UNIT WITH 600 OHM INPUTS, SWITCH “TERM” TO "OFF" POSITION (DOWN).

STARTING WITH THE “INPUT” AND “OUTPUT” CONTROLS AROUND 9:00, SELECT THE DESIRED “RATIO”: "4" OR "8" FOR COMPRESSION, "12" OR "20" FOR LIMITING. NOTE THAT THE “RATIO” CONTROL ALSO SELECTS THE THRESHOLD, WITH "4:1" BEING THE LOWEST AND "20:1" INVOLVING A VERY HIGH THRESHOLD.

ADJUST THE “INPUT” LEVEL FOR DESIRED AMOUNT OF GAIN REDUCTION. AS THE CIRCUIT CAN CONSIDERABLY BOOST GAIN WITH +4 LEVELS, 9 TO 11:00 SHOULD BE OPTIMUM. EACH LED ON THE INNER METER INDICATES APPROXIMATELY 2 DB OF GAIN REDUCTION.

NOW ADJUST “OUTPUT” LEVEL AS DESIRED. TOGGLING THE “BYPASS” SWITCH WILL ALLOW RAPID GAIN MATCHING. NOTE THAT THE METERS SHOW NOTHING WHEN THE UNIT IS BYPASSED. THE OUTPUT METER IS CALIBRATED FOR 0DB = +6DBM, BUT CAN BE EASILY RECALIBRATED BY ADJUSTING R122 ON THE MAIN PCB.

“ATTACK” AND “RELEASE” CONTROLS CAN NOW BE DEFINED. "ATTACK" AROUND 10 OR 11:00 AND "RELEASE" AT ZERO SHOULD PROVIDE A PROPER STARTING POINT FOR MOST SIGNALS.

FOR STEREO USE: SET UP BOTH CHANNELS WITH “LINK” OFF, MATCHING GAIN REDUCTION AND LEVEL AS CLOSELY AS POSSIBLE. ENGAGING “LINK” CONNECTS THE TWO LEVEL DETECTORS TOGETHER AND THUS SENDS THE SAME GAIN REDUCTION CONTROL VOLTAGE TO BOTH CHANNELS, PREVENTING UNWANTED SHIFTING OF THE STEREO IMAGE. NOTE THAT WHEN LINKED, ONLY THE LEFT “ATTACK” AND “DECAY” CONTROLS ARE ACTIVE. ALL OTHER CONTROLS REMAIN INDEPENDENT. PLEASE BE AWARE THAT THE FIRST SETTING OF THE “RATIO” CONTROL IS "OFF". THIS ALLOWS THE UNIT TO PASS A SIGNAL WITHOUT ANY GAIN REDUCTION; EXCELLENT FOR 'WARMING' SIGNALS OR RAISING LEVELS OF WEAKER SIGNALS.

THAT'S ALL FOR NOW. ENJOY AND CHECK OUR WEB SITE PERIODICALLY FOR MORE INFORMATION. WORK ON THE COMPLETE MANUAL IS UNDERWAY BY THE INCREDIBLY OVERWORKED STAFF AT STUDIO ELECTRONICS. THANK YOU FOR YOUR CONTINUED SUPPORT.

TIM CASWELL, SOMEWHERE IN A 'WISCONSIN STATE OF MIND', 8.03.02.


Mail: Tim@studioelectronics.com
Web: http://www.studioelectronics.com

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