TUBE-TECH CL 1B Compressor
Contents
1. If the voltage exceeds this value replace either IC1 or IC2 THE GRE SHALL BE MARKED BETWEEN 1 225 1 285 ADJUSTMENT OF BASIC GAIN Apply a signal of 1 kHz 30 0 dBU into the input of the compressor Turn the GAIN control fully clockwise Set the RATIO control at_2 1 Adjust the pre set GAIN located on amp psu PCB to an output reading of_0 0 dBU ADJUSTMENT OF COMPRESSION TRACKING Turn the THRESHOLD control fully counter clockwise Set the RATIO control at_2 1 Set the BUS select switch at 1 Apply a signal of 1 kHz 0 0 dBU into the input of the compressor Adjust the GAIN control to an output reading of 0 0 dBU Apply a DC voltage of 250 0 mV into the side chain jack socket tip and observe that the output level has dropped to 10 0 dB If this is not the case adjust the level with P 2 P 1 to obtain a drop of exactly 10 0 dB The trimpots in parenthesis refers to PCB 870316 0 1 2 980810 LYDKRAFT ApS Mose All 20 DK 2610 R dovre Denmark 10 NB Turn the THRESHOLD control fully counter clockwise Switch the METER selector to Compression Set the RATIO control at_2 1 Apply a signal of 1 kHz 0 0 dBU into the input of the compressor Adjust the GAIN control to an output reading of_0 0 dBU Adjust P 4 P 2 until the meter is reading 0 VU Apply a DC voltage of 250 0 mV into the side chain jack socket and observe that the output level has dropped to 10 0 dBU If this is not the case adjust2. the point where the compressor begins its action It is defined as the point where the gain is reduced by 1 dB The threshold is continuously variable from 20dBU to 40 dBU The VU meter switch has three positions 1 Input The meter is reading the level at the input socket 2 Compression The VU meter is reading gain reduction Its rest position is 0 VU and the amount of compression is shown as a decreasing deflection in dB 3 Output The VU meter is reading the level at the output socket 0 VU is equivalent to 4 dBU Leave the meter switch in position compression as it might OON A EAT This leverswitch switches the compressor in and out of the signal path The out position bypasses the entire compressor The attack control chooses how fast slow the compressor responds to an increase in the input signal The attack control is continuously variable from 0 5 to 300 milliseconds The release control chooses how fast slow the compressor responds to a decrease in the input signal The release control is continuously variable from 0 05 to 10 seconds 980112 LYDKRAFT ApS 3 Mose All 20 DK 2610 R dovre Denmark ATTACK RELEASE SELECT This switch selects how the compressor reacts to an increase attack or decrease release of the input signal There are three settings of the switch 1 Fixed Attack time 1 msec Release time 50 msec 2 Manual Attack time from 0 5 msec to 300 msec Release time from 0 05
3. DESCRIPTION The TUBE TECH compressor CL 1B differs from many other compressors in that the gain reduction element is made from a non semiconductor element which in itself has a very low harmonic distortion and none of the non linearity problems involved when using most semiconductor elements Furthermore there is no long term degradation of the element thus giving it almost infinite life This element is placed after the input transformer of the compres sor and followed by an all tube based amplifier with a gain of dB to 30 dB Thus the signal is not fed through any semiconductor circuitry on its way to the output The amplifier consists of two tubes valves in push pull configuration one ECC 83 as the pre amp and phase splitter and one ECC 82 as the output stage and an output transformer The power supply for the pre amp and phase splitter are stabilized and the heaters of both tubes valves are fed with a stabilized DC voltage The whole amplifier including input and output transformer and the power supplies are placed on one PC board Both input and output are balanced 600Q and fully floating The in out key switches the compressor in and out without clicks THE SIDECHAIN The side chain is the only part of the compressor that contains semiconductors They are used for three reasons First they do not affect the sound reproduction second they have a high slew rate which is of importance for the performance of the com
4. ack release time the threshold and the ratio on that unit and turn the threshold fully counter clockwise on the reminding compressors It is of course possible to have all the interconnected compressors control each other simultaneously NB Remember to set the ratio control and the gain control in the same position on the slaves Otherwise the stereo image could be shifted during compression The attack release control on the slaves will have no effect The input output capability of the side chain circuit allows up to ten compressors to be linked together They are connected in parallel with a standard 1 4 stereo jack jack cord tip bus 1 ring bus 2 The two jack socket on the rear panel is connected in parallel and both are input output 980112 2 LYDKRAFT ApS Mose All 20 DK 2610 R dovre Denmark CONTROLS GAIN RATIO THRESHOLD METER IN OUT ATTACK RELEASE The gain control is used to make up for the gain loss which takes place when the unit is compressing It is placed after the gain reduction circuit and therefore has no influence on the threshold setting The gain control is continuously variable from off to 30 dB The ratio control varies the ratio by which the input signal is compressed If the ratio selected is to 2 1 and the input signal increases 10 dB the output signal is only increased by 5 db The ratio control is continuously variable from 2 1 to 10 1 The threshold is
5. pressor and third they don t take up much room It contains two J FET quad op amps one npn transistor and one FET transistor which handles the signal for the gain reduction element The compressor contains two time constants circuits 1 Fixed attack and release times 2 Variable attack and release times The attack release select switch makes it possible to use these two circuits separately or combine their functions This gives a feature not normally obtained in other compressors In the combined fix man state the attack and release controls makes it possible to obtain a complex release time slope See page 4 980112 LYDKRAFT ApS 1 Mose All 20 DK 2610 R dovre Denmark COMPRESSOR INTERCONNECTION The side chain sockets for interconnection of several compressors are located on the rear panel A switch BUS SELECT on the front selects which compressors are interconnected and on which bus they are connected If you e g have 10 compressors in a rack you can select compressor 1 5 7 and 8 on bus 1 and compressor 2 3 6 and 9 on bus 2 leaving compressor 4 and 6 in the off position Compressors 1 5 7 8 are now interconnected and all four will perform the exact same compression This applies to compressor 2 3 6 and 9 as well Compressor 4 and 6 are independent The interconnection implies that the unit which performs the most compression is controlling the others To choose which one you want to control select the att
6. s left in the off position it works entirely independently 980112 4 LYDKRAFT ApS Mose All 20 DK 2610 R dovre Denmark In the following you will find suggestions on various applications of the TUBE TECH compressor CL 1B They are given as a convenient guide to enable you to familiarise yourself with the different aspects of using the compressor We have not mentioned specific settings of gain and threshold as they are dependent upon input levels Instead we have specified how much compression in dB we feel is needed for the various examples OVERALL COMPRESSION FINAL MIX COMPRESSION NEEDED 3 4 dB Attack release select Fix man Attack 2 o clock Release 10 o clock Ratio 9 o clock STANDARD COMPRESSION BASS PIANO GUITAR KEYBOARDS AND VOCALS COMPRESSION NEEDED 4 5 dB Attack release select Manual Attack 2 o clock Release 10 o clock Ratio 10 2 o clock LINE GUITAR AND PIANO COMPRESSION NEEDED 10 dB Attack release select Manual Attack 7 o clock Release 1 o clock Ratio 3 o clock COMPRESSION OF DRUMS SNARE AND BASS DRUM COMPRESSION NEEDED 2 3 dB Attack release select Fixed Ratio 9 12 o clock 980112 LYDKRAFT ApS Mose All 20 DK 2610 R dovre Denmark ADJUSTMENT PROCEDURE CAUTION Observe that the offset voltage measured at the side chain jack socket when the THRESHOLD is off is not greater than 15 mV DC in both position fixed and manual tip is bus 1 and ring is bus 2
7. sec to 10 sec 3 Fix man This setting combines the release times of fixed and manual mode The attack time is as in the fixed mode The fix man mode always has a fast attack but it is possible to obtain a release time depending on the input signal e g get a fast release when the peak disappears then superseded shortly thereafter by the release time selected by the release control From the time the peak disappears until the selected release time takes over is dependent upon the setting of the attack control That is the attack control changes function from a pure attack control to a control of delay with the same time range The more CW the attack control is turned the longer time before the release control takes over The more CCW the attack control is turned the shorter time before the release control takes over This function is valid only if the time of the peak is shorter than the setting of the attack control If the peak of the program is longer than the setting of the attack control or if the attack control has reached the full CCW position it will respond as in the manual mode The fix man mode acts as an automatic release function with a constant fast attack time and fast release time for short peaks and a longer release times for longer peaks This setting is mainly intended for use on program material overall compression BUS SELECT Interconnects several compressors on bus 1 or bus 2 If the compressor i
8. the compression tracking see above Adjust P 3 until the meter is reading 10 0 VU Remove the DC voltage from the side chain jack socket Repeat step 6 9 The VU meter accuracy should be within 0 5 dB when reading compression ADJUSTMENT OF THE RELEASE CONTROL Set the METER switch in position compression Set the attack release SELECT switch in position manual Apply a signal of 1 kHz 0 0 dBU into the input of the compressor Adjust the THRESHOLD cortrol to a reading of_ 10 VU of the WVU meter Set the ATTACK control at fast Set the RELEASE conirol at slow Switch off the 1 kHz and observe that the VU meter moves to O VU in approx 10 sec If this is not the case adjust P 1 P 5 to obtain a release time of approximately 10_ sec The trimpots in parenthesis refers to PCB 870316 0 1 2 950119 LYDKRAFT ApS 7 Mose All 20 DK 2610 R dovre Denmark Vie 0 to 30 dB compression 5 Hz 25kHz 0 5 3 dB lt 0 15 lt 0 15 26 0 dBU 21 0 dBU Unweighted CCIR 468 3 85 0 dBU 75 0 dBU 75 0 dBU 65 0 dBU 600 Ohms lt 60 Ohms continuously variable from 2 1 to 10 1 continuously variable from 40 dBU to 20 dBU continuously variable from off to 30 dB lt 1dB LYDKRAFT ApS Mose All 20 DK 2610 R dovre Denmark
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