User Manual
Contents
1. Audio User Manual C1 VALVE COMPRESSOR Tony Larking Professional Sales Limited Letchworth England Tel 01462 490600 International 44 1462 490600 Fax 01462 490700 International 44 1462 490700 22626262 22 2 59555952525 55559555955 0000606000006 006060600006 0000000060 THRESHOLD ATTACK RELEASE INPUT SELECTOR FAST SLOW FAST SLOW HP FILTER SWITCH h A BYPASS ON 16 60 1 1 5 1 30 0 20 SWITCH GAIN MAKE UP INPUT GAIN RATIO PHANTOM POWER LED FIG 2 COMPRESSOR CONTROLS UNBALANCED LINE INPUTS AND OUTPUTS DISCONNECT FROM MAINS BEFORE REMOVING COVER TL Audio UALUE COMPRESSOR TO REDUCE RISK OF ELECTRIC SHOCK DO NOT EXPOSE TO RAIN OR MOISTURE UNBALANCED NBALANSED INPUTS SERIAL NUMBER NO USER SERUICEABLE PARTS INSIDE REFER SERUICE TO QUALIFIED PERSONNEL 8 B A Se WARNING THIS EQUIPMENT MUST BE EARTHED MADE IN ENGLAND CHANNEL INPUTS CHANNEL A INPUTS BALANCED OUTPUTS NOMINAL SIDECHAIN LINE MIC LINE CAUTION CHANNEL 8 CHANNEL A LEVEL L INSERTION POINTS ENSURE CORRECT VOLTAGE bee SET BEFORE CONNECTING A TO AC MAINS SUPPLY babe G REPLACE WITH CORRECT RATING ONLY SEND RING 4 RETURN SLE UE PIN 1 GND PIN 2 UE PIN VE FUSE IEC INLET BALANCED NOMINAL OUTPUT INPUT SOCKETS OUTPUTS LEVEL SWITCH VO2. Also a fast release setting will be extended by a slow attack setting Due to this automatic modification of the time constants the controls are simply calibrated fast to slow Ratio The ratio may be varied from 1 1 5 very gentle compression to 1 30 near limiting The compressor normally operates with a i e the compression is gradually introduced as the signal passes the threshold in which case the ratio refers to the compression eventually obtained Gain Make Up Up to 20dB of gain make up may be applied to retain the subjective loudness of the signal Stereo Operation In normal 2 channel operation the controls operate independently for each channel The compressor may also be set for full stereo operation where the Threshold Attack Release and Ratio controls for channel A control both channels The input gain and gain make up controls remain separate to allow relative input output gain balance adjustment In stereo mode the control voltages are also linked ensuring that the same amount of gain reduction is applied to both channels even if one signal is below the threshold This ensures that the stereo image is preserved VU Meters The compressor is equipped with twin illuminated VU meters These meters normally monitor the audio output from the unit and are calibrated for OVU 4dBu The reference point may be internally adjusted by your dealer if required The meters may
3. a signal It may be used to keep a variable output from a bass guitar for example at an even level or to add punch to vocals drums guitar or a complete mix Whist the subjective sound quality can be improved by compression the overall signal level may be reduced A gain make up control at the output of the compressor stage allows the signal level to be brought back to the same loudness as the uncompressed signal Frequency selective compression may be obtained by inserting an equaliser into the sidechain signal from which the control voltage is generated Threshold The TL Audio compressor has a variable threshold set by a rotary control calibrated from 20dBu to 20dBu resulting in increased compression as the control is rotated clockwise Attack and Release The attack time is variable from 0 5msec to 50msec At 0 5msec attack the compressor is fast enough to reduce the gain of a 1KHz signal in less than half a cycle effectively preventing an overload of any following equipment which has limited headroom such as a digital processor tape machine or transmitter The release time is variable from 40msec to approximately 4 seconds Adjustment of the attack and release times allows unobtrusive compression to be applied to virtually any audio signal but should very short transients occur the time constants become signal dependant generally reduced to prevent a slow release leaving a hole in the signal after the transient
4. LTAGE SELECTOR SWITCH INSERTION POINTS FIG 3 REAR PANEL PHANTOM POWER 480 OUTPUT AMPLIFIER MIC INPUT VALVE STAGE 1 BYPASS SWITCH OUTPUT VOLTAGE RHPLIFIER LINE INPUT INPUT INPUT AMPLIFIER p SELECTOR SWITCH HP FILTER AUX INPUT SIDECHAIN ae PROCESSING SIDECHAIN INSERTION POINT VALVE STAGE 2 COMPRESSOR CONTROL VOLTAGE FIG 1 BLOCK DIAGRAM INTRODUCTION The T L Audio Valve Compressor combines classic valve techniques with low noise solid state circuitry to produce a unit offering a fully controllable compressor on each of its two channels Both channels feature balanced and unbalanced line level inputs plus a mic input with switchable 48V phantom powering Further flexibility is provided from a front panel auxiliary input which accepts mono or stereo keyboard and guitar inputs Typical applications include direct recording to tape instrument preamplifier use as outboard equipment during mixdown and as a main stereo compressor for monitoring and PA systems The block diagram of one of the channels is shown in fig 1 A solid state electronically balanced input amplifier is used to achieve state of the art performance with very low noise low distortion and wide bandwidth The input includes a switchable second order high pass filter 3dB at 90Hz to remove unwanted LF noise A triode valve is used as a second stage voltage amplifier to obtain the cl
5. Threshold 20dBu to 20dBu Attack 0 5msec to 50msec Release 40msec to 4 seconds Ratio 1 1 5 to 1 30 Gain Make Up 0 to 20dB Stereo Operation VU Meters Outputs Ganged Threshold Attack Release and Ratio controls Linked control voltages Switchable to output level or compression OVU 4dBu Electronically balanced unbalanced compatible Rear panel selectable for 4dBu or 10dBu nominal level Output impedance less than 10 ohms Maximum level 26dBu into 10Kohms 22dBu into 600 ohms 4dBu nominal balanced 3 pin male XLR connector Unbalanced Outputs Output impedance 47 ohms Maximum level 20dBu into 10Kohms 2 pole 0 25 jack socket Frequency Response Noise 10Hz to 40KHz 0 1dB Noise floor 85dBu with line input at 0dB gain and compressor by passed 80dBu with compressor active 4dBu nominal level 95dBu and 90dBu respectively at 10dBu nominal level Dynamic Range Distortion 1064 THD N 0 05 10Hz 40KHz IMD 0 03 Line input at 0dBu and 0dB gain with compressor in after 10 minute warm up time Sidechain Insertion Points Unbalanced switched 3 pin jack socket tip send ring return Nominal level 2dBu Output impedance 47 ohms Return input impedance 10Kohms Power Requirements Dimensions Weight Rear panel selectable for 220 240V 50Hz or 110 120V 60Hz operation Rear panel fuse 20mm 1 Power consumption 30VA typical De
6. assic valve sound and gradual overdrive characteristics Two XLR input sockets are provided per channel for mic and line inputs The mic input is suitable for low impedance 150 600 ohm microphones with a gain control range of 16 to 60dB 48V phantom power is available on each channel The line input has an effective overall gain range of 10 to 35dB allowing the valve stages to be fully driven from line level signals in the range 20 to 20dBu A front panel mounted auxiliary jack socket for each channel allows mic or line level inputs to be easily connected to the compressor The aux input may be used for a stereo keyboard or mono guitar etc An insertion point is provided in the sidechain circuit to allow an equaliser or other processor to be used for frequency conscious compression etc The insertion point is unbalanced at a nominal operating level of 2dBu The sidechain processing is solid state whilst a second triode valve stage is employed in the compressor circuit The compressors feature continuously variable controls for threshold attack release ratio and gain make up A certain degree of programme dependant variation is incorporated particularly of the attack and release times Full stereo operation is supported with ganged controls and linked control voltages The compressors may be by passed for A B comparison Twin illuminated VU meters are provided which may be switched to monitor the output signal level or compre
7. be switched to indicate the amount of compression occurring If the signal is below the threshold the meters will indicate OdB i e no gain reduction As the signal passes through the threshold the meter will indicate the gain reduction occurring at the compressor stage Note that the gain reduction indicated is a measure of the degree of compression and does include any gain make up applied Mic Input Line Input SPECIFICATIONS Electronically balanced input impedance greater than 10Kohm to suit 150 600 ohm microphones 48 phantom power available indicated by red LED Gain range 16 to 60dB Noise EIN 126Bu at maximum gain with a 150 ohm termination measured 22Hz 22KHz unweighted Maximum input level 10dBu 3 pin female XLR connector Electronically balanced unbalanced compatible with input impedance greater than 5Kohm Gain range 10dB to 35dB suitable for nominal input levels from 20dBu to 20dBu Maximum input level 30dBu 3 pin female XLR connector Unbalanced Input Input impedance greater than 5Kohm Gain range 10dB to 35dB suitable for nominal input levels from 20dBu to 20dBu Maximum input level 24dBu 2 pole 0 25 jack socket High Pass Filter Second order 12dB per octave 3dB at 90Hz Auxiliary Input Mono or Stereo input Switchable for high level Keyboard or low level Guitar inputs Maximum input level 10dBu 2 pole 0 25 jack socket Compressor
8. et The unit may be set for 115V accepting voltages in the range 110V to 120V 60Hz AC or to 230V for voltages in the range 220V to 240V 50Hz AC The fuse required is 20mm anti surge 1AT Warning attempted operation on the wrong voltage setting or with an incorrect fuse will invalidate the warranty Audio Inputs Each channel has two female 3 pin XLR connectors for mic and line sources Both are compatible with either balanced or unbalanced signals when the mating connectors are appropriately wired Balanced inputs Pin 1 Ground screen Pin 2 Signal Phase or hot Pin 3 Signal Non Phase or cold Unbalanced inputs Pin 1 Ground screen Pin 2 Signal Phase or hot Pin 3 Signal Ground When using unbalanced signals the signal ground may be obtained by linking pins 1 and 3 in the mating XLR connector Good quality screened cable should be used particularly for microphone or low level sources to prevent hum or noise pickup Unbalanced Line Inputs An unbalanced line level input is provided for each channel on a 0 25 mono jack socket The mating plugs should be wired as follows Signal Phase hot Screen Ground Auxiliary Inputs A 2 pin mono jack plug is required which should be wired as follows Tip Signal Phase hot Screen Ground Insertion Points The insertion p
9. l amount of heat internally This heat should be allowed to dissipate by convection through the grill in the front panel which must not be obstructed Do not locate the unit where it will be subject to external heating for example in the hot air flow from a power amplifier or on a radiator The compressor may be free standing or mounted in a standard 19 rack Rear Panel The rear panel connectors are identified in fig 3 OPERATION Front Panel The front panel controls for one channel are identified in fig 2 Input Stage Ensure that the correct input connector mic or line is being used and that the front panel switch is set to the appropriate position Note that both mic and line inputs may be connected at the same time but only one is selected The input selector switch selects between the line input mic input mic with 48V phantom power signalled by a red LED and the Aux input CAUTION Switching phantom power on or plugging a microphone in with phantom power applied may cause a click or thump in your loudspeakers To prevent this happening ensure that the system gain is set to minimum e g on your mixing console fader or power amplifier before operating the switch or plugging in a microphone If the gain required is not known set the control to minimum with the EQ by passed and gradually increase the gain until the required output level is achieved Auxiliary Input The front panel auxiliary input
10. oints are interfaced via a 3 pin 0 25 switched jack socket on the rear of the unit The pin connections are Sleeve Ground Tip Send Ring Return The insertion point is unbalanced and operates at a nominal level of 2dBu If used as an additional send only e g as a send to a tape machine or monitor mixing desk the Tip and Ring should be wired together to preserve the signal path through the insertion point Outputs The outputs are via balanced 3 pin male XLR connectors The mating connectors should be wired as follows Pin 1 Ground screen Pin 2 Signal Phase or hot Pin 3 Signal Non Phase cold If an unbalanced output is required pins 1 and 3 should both be connected to ground Nominal Output Level A switch on the rear panel allows the output to be matched to equipment at a nominal operating level of 4dBu or 10dBu Most professional equipment requires 4dBu approximately 1 2V rms but some small mixing consoles portable tape recorders or domestic audio equipment require 10dBu approximately 225mV rms The switch should be set to the position which results in the best signal to noise ratio whilst preserving sufficient headroom Unbalanced Outputs An unbalanced line output is provided for each channel on a 0 25 mono jack socket Tip Signal Phase hot Screen Ground Ventilation The unit generates a smal
11. sockets may be switched between high level signals Keyboard and low level pick ups Guitar and are provided with an input gain control Note that the channel gain controls remains operative when the Aux input is selected The two aux input sockets may be used for example for a stereo keyboard The compressors may be operated independently or linked for true stereo operation Aux A input is also normalled to the B input so both channels may be driven from a mono input guitar etc With different channel gain settings one channel may be lightly compressed whilst a higher degree of compression is applied to the high gain channel resulting in stereo effects from a mono input Compressor Operation A compressor functions by reducing the gain of the signal when it exceeds a certain level or threshold The amount of gain reduction may be fairly gentle through to limiting where the signal is clamped at the threshold level The amount of gain reduction is determined by the ratio control which is calibrated as a ratio of the output to input signals The gain of the signal is reduced by a voltage controlled circuit Variable time constants are applied to the control voltage to adjust the rate at which the gain is reduced called the attack time and the rate at which unity gain is restored after the signal returns to below the threshold referred to as the release time The effect of compression is to limit the dynamic range of
12. ssion applied A solid state electronically balanced output stage with XLR connector completes the channel Dedicated unbalanced outputs are also provided on jack sockets The outputs are switchable for 4dBu or 10dBu nominal output level Please read this manual fully before installing or operating the Compressor PRECAUTIONS The T L Audio Valve Compressor requires very little installation but like all electrical equipment care must be taken to ensure reliable safe operation The following points should always be observed All mains wiring should be installed and checked by a qualified electrician Ensure the correct operating voltage is selected on the rear panel before connecting to the mains supply Never operate the unit with any cover removed Do not expose to rain or moisture as this may present an electric shock hazard Replace the fuse with the correct type and rating only Warning This equipment must be earthed INSTALLATION AC Mains Supply The equaliser is fitted with an internationally approved 3 pin IEC connector A mating socket with power cord is provided with the unit wired as follows Brown Live Blue Neutral Green Yellow Earth Ground All mains wiring should be performed by a qualified electrician with all power switched off and the earth connection must be used Before connecting the unit to the supply check that the voltage selector switch on the rear panel is correctly s
13. tachable 3 pin IEC connector mating connector and cable supplied Front panel On Off switch with green LED 19 rack mounting 2U high 483mm wide x 88mm high x 205mm deep 6Kg In line with a policy of continuous development the above specifications are subject to change without notice SERVICE Should the compressor require service it must be taken or posted to an authorised dealer Please retain the original packing for possible future use and ensure the unit is suitably protected during transit The manufacturer cannot accept responsibility for damage caused during transportation The compressor is protected by a limited warranty for a period of one year from the date of purchase During this period any faults due to defective materials or workmanship will be repaired free of charge The warranty excludes damage caused by deliberate or accidental misuse operation on the incorrect mains voltage or without the correct type and value of fuse fitted It is the user s responsibility to ensure fitness for purpose in any particular application The warranty is limited to the original purchase price of the equipment and excludes any consequential damage or loss Please retain proof of purchase and record the following details Serial Number Date purchased DIE E cid ka aan yt eaten cise
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