A3 - TL Audio
Contents
1. 15 LE EEEE EE Aaa a ae Aenea Aa ee a A 16 DO LLG ere eee ER ET TPT EOE SREP OEP 16 RT TEST eC Er E E CEPR Pty PERT 16 EOS ON iss aC TESA SLA RESEMBLED NESS BESS ceisler RE 16 EC OPC Tas CUES ESET ENS ERTS ASE 16 Output GI cos cS EASELS ERTIES LUA UAT Bee 16 Digital OULU ss cis cea RTS EERIE EERE ARSE SOLUTE ERA AEE ASE ah ieee 17 Output Reak Sees ines aaa ans leeks a AE Danaea 17 GETTING STARTED visene soii i E E Ee E E i is 18 CONNECTIONS 18 19 SPECIFICATION scssssssssssssosessssssosecscsssoscsscsssescsscsssnscsscsssnscsscsssescsscssssscsscssssscsssscssscsesscsssssasscsssssosacssoes 21 MICUN Ut rs 21 PANGINDUL tata dia 21 dnstr ment Input aneii een E ARAE 21 High 21 insertion Pomi osctoie e E AA R AR RE sews 22 aaa ae eka Deen EEE 22 E 222. 22 QUIS A SANEA BEREA PAA DE NEAN E ENANA 22 23 POWEPPRQUIFEMONISE EEE EE EEEE NEE E OEE ETS EESE ENDENE EEN EE EE Tath 23 23 SERVICE ccc csssadecshecedsics sceasscesdedeiseedeteudsesussseseduadeazeseaccsssanecesaedesdeussisaceetscssssanedsvsosassuasossedeedeaseseacesasdssesssedssieee 24 INTRODUCTION The TL Audio Ebony Series of audio processors are a sleek looking range of discrete Class A processors designed to heighten your audio experience they use signal paths constructed from discrete transistor Class A circuits with switchable variable drive tube stages putting you in control of how creamy or how cool your unit sounds These techniques provide very high quality uncoloured audio with the option to add valve warmth at the touch of a button Hand assembled in England to the highest standards the Ebony uses stylish quality chrome knobs together with a high gloss black finish to make the exterior look just as smooth as the circuits sound The Ebony Series have all the features you come to expect with TL Audio including balanced I O multi input options analogue VU metering and intuitive precise controls All units are also compatible with the TL Audio DO 2 digital SPDIF interface for easy digital connectivity w
3. and out you can compare the levels and the subjective sound quality of the original and compressed signals With the compressor active use the Gain Make Up control to set the level so that when disabling the compressor there is no level drop This way you can A B the original and compressed signals without the levels changing 7 At this stage if you are unfamiliar with compression you should experiment with 19 each control to see how it affects the sound If in doubt aim to use compression gently as it can be difficult to compensate for over compression if you later decide that too much effect was used On the other hand there are no rules so if extreme settings get you the effect you are after the choice is yours Let your ears be the guide 8 Engage the EQ section and experiment with applying some EQ You should find that the LF amp HF bands are useful for adding some low end warmth and high end air whilst the mid band is more useful at removing boxiness or nasal tones from mic sources Unlike other EQ s you should find that you can apply quite drastic amounts of EQ boost and the unit will still retain its musicality and not introduce unwanted harshness 20 SPECIFICATION Mic Input Discrete Class A circuitry from input to output unless Tube stage In Gain Range 16dB to 60dB 14dB to 30dB with pad Maximum Input level 10dBu without pad 30dB with pad Frequency Respon
4. If an unbalanced output is required pins 1 and 3 should both be connected to ground Ventilation The unit generates a moderate amount of heat internally which should be allowed to dissipate by convection through the grills in the sides and 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 or in direct sunlight The unit may be free standing or mounted in a standard 19 rack 10 OPERATION Input Stage The input gain control sets the level of the mic line and instrument signals into the Ebony A3 The 2 position button above the input gain and Tube Warmth knob selects the signal source Input choices are Mic for dynamic or most ribbon microphones and condenser microphones that require phantom power Line and Instrument For condenser microphones you should also press the 48V button to activate phantom power The Instrument input allows high impedance instruments such as guitars or a bass etc to connect directly into the Ebony A3 and eliminates the need for a DI Direct Injection Box For even better performance you also have a button at the input stage to enable you to switch between high and low impedance instrument inputs Increasing the input gain control setting will also have a pronounced effect on the amount of compression as the threshold will remain constant as the
5. Overview of Compressor Operation To operate the Ebony A3 successfully an understanding of each control will help to obtain the best results If you are unfamiliar with the effect of compression it may help to adjust the controls to extreme settings and listen to the sonic effect Generally compressors are used in two different ways either to enhance the signal and control the dynamic range as unobtrusively as possible or used more severely to specifically to create an effect Threshold The Threshold is the point measured in decibels that any compression comes into operation The Threshold control is variable from 20dB in the most anticlockwise position to 20dB at the most clockwise position Any signal below the Threshold passes through the unit unaffected while signals above the Threshold are reduced in gain and are thus compressed This does depend on the Soft or Hard knee to some 13 extent as the Soft knee is more gradual around the Threshold point Unlike some compressors the Threshold control on TLA units including the Ebony A3 starts at a zero point value in the counter clockwise position and decreases to a minus value as you rotate the control clockwise The reason for this is as you turn the Threshold control on the Ebony A3 clockwise i e towards the negative region then the degree of compression will increase We think this is logical whereas the common method of turning the control down to achi
6. for example the internal wiring of 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 If the wiring needs to be changed the unit must be taken to an approved service centre Alternate supply voltages may also require a different power cable or mains plug If in doubt consult local electrical regulations Warning attempted operation on the wrong voltage setting or with an incorrect fuse will invalidate the warranty Audio Inputs Mic Input There is a female 3 pin XLR connector for connection to a microphone The microphone will normally be balanced but unbalanced connections may also be made as follows 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 Line Input A second 3 pin XLR connector is provided for connection to a line level source The signal may be balanced or unbalanced and connections may also be made as follows 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
7. variable intensity Drive LED and the Peak LED Where instrument inputs are present on the Ebony models dedicated valve input stages are used Switchable to high or low sensititivity and impedance these input stages represent the ultimate quality for the first stage of instrument amplification Why Balanced I O Balanced I O Inputs and Outputs are always preferable to unbalanced connection in an audio system A balanced signal consists of signal phase and non phase connections which form a differential pair independent of the ground or earth connection Noise particularly mains hum and high frequency interference can often be present in unbalanced systems due to small differences in ground potential or circulating ground currents loops between units where the signal phase only is taken as an absolute value with respect to ground A correctly designed balanced interface should have both phase and non phase signals of equal magnitude and source impedance but should allow either of the phase and non phase signals to be connected to an arbitrary electrical point e g ground without changing the differential level Therefore if for instance the non phase signal is shorted to ground by an unbalanced input on a piece of equipment then the phase signal should double in magnitude to compensate Such an arrangement is referred to as floating or ground free Balanced signals require 3 pin connectors such a
8. 5dB 80Hz shelving 22 Mid 15dB swept 150Hz to 7KHz Q 0 7 HF 15dB 12KHz shelving Pre and Sidechain Compressor switches Metering Tube Drive LED Variable intensity over 10dB level range typically corresponding to 1 to 5 THD Tube Peak LED Dependant on level and drive typically corresponding to 10 THD Output Peak LED 19dBu on output VU Meter Switchable to Input Ouput or Gain Reduction Nominal calibration OVU 4dBu 10dB switch calibration OVU 14dBu Power Requirements Internally set to 230V 50Hz or 115V 60Hz operation Detachable IEC power cord Power consumption 28VA Dimensions 2U rack mounting or free standing W x H x D 483mm x 88mm x 200mm 19 0 x 7 9 x 3 5 behind front panel Shipping weight 6Kg The above specifications are typical values and do not represent limits for any particular unit These specifications are subject to change without notice 23 SERVICE Should the unit require service it must be taken or posted to an authorised dealer with a description of the fault 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 This equipment is supported by a limited warranty for a period of one year from the date of purchase During this period any faults due to d
9. E RARE 9 OUP Ub savers sce RRR ARERR AE AEA NR EAA A EERE TERA LG RABE AA RRR RE ee 10 Ventil NON i E EEE E REET PTET EPS PCP RT EE rere Tae EERE 10 OPERATION ccsssscsssscsssscsssscsssssssessssssssscessssessssesecsssesssssessssesensesssssssssssssssesesssssssassssessssessesesessessessssesenoes 11 PUSIO es 11 Microphon eIn E 11 POOR PN OOOO S A URE TRE TIC POT ORSON RNP TTI TICY IO eT ITE TSEC NNS 11 INEN S E A 11 BSE POAT A S ERS RRO 12 SE CAS HALT eM URE 12 Phantom PO WOH es 12 Tube Stage Drive and Peak 5 12 WHAT IS COMPRESSION csscsssesesssssseseeseseseseseesenesescesenesesescesenesesceseneneseseeseneseaeesesenesesceseneseseseneneseeseneneses 12 Overview of Compressor Operation 13 UBT LAY 10 Pa TE CPPCC PPLE CREE R PETE TET A A A 13 Attack Gi REI 14 Make OD si stig cc EEL TREE RRR EERE RATNER ANE REAR RR 15 Compressor ONE Biases EUSA EEG ERE RSET SRE REET RARER GEER 15
10. T L Audio User Manual Ebony Series A3 Mono Processor TL Audio Limited Letchworth England Tel 01462 492090 Fax 01462 492097 www tlaudio co uk email info tlaudio co uk CONTENTS INTRODUCTION 0 cscscssscssscsssecsssccssssssssssssssesscssssssssssssscssssesessesscsssesssssessssessesesecssseessssessssessesesenseseaseees 3 WHY CLASSA Vori uneen Passe anes 4 WHY DUBES casi cnet eek Ode 4 WHY BALANCED VO 5 lt ccsscssssssssecsssecssscsssssssssesscsssessssesssssessssessesesecsssssssssessssesessesecsesscssssassssesseseseeseseaseees 6 PRECAUTIONS 7 INSTALLA 8 AC Mains amp 8 MAT CAN Ub oes cscs STEELERS ERE TSR EOE EERE EET Te ca etal 8 TENE AN PUL 9 Instrument Inputs a i n RA ERAR R SEER EUSA EASES RSE SESSA LRAT Sth ee AA ARER 9 TNSCVULON POUNE AREA AREA RTE ass RATER LUR
11. ack to the insert return connection thus returning the processed signal to the mixer and ensuring continuous signal flow Group insert points are used to process sub grouped signals such as drums or backing vocals It s possible to mix a group of voices or instruments to a single group and then use that group fader to control the overall level rather than having to adjust each individual voice or instrument level If you then wish to compress the overall group signal you can connect a Ebony A3 to the relevant group insert point using the same send and return technique as the channel insert 18 The optional digital output will allow high quality 24 bit A D conversion of the Ebony A3 mono output on a coaxial SPDIF connector The DO 2 can feed directly into digital recorders such as Digital Multitrackers Hard Disk Recorders DAT Recorders Minidisk and CD Recorders bypassing any A D conversion stages on the way When connecting the DO 2 s SPDIF output it is advisable to use cables less than 5 metres in length and of high quality The digital output can be used simultaneously with the Ebony A3 s analogue output In Use Having connected the Ebony A3 it s time to put it into action Here s a simple step by step guide 1 We ll assume that a condenser microphone is connected to the Ebony A3 mic input and the 48V phantom power is engaged The first stage is then to set up the gains of the Ebony A3 With the compress
12. e equaliser ahead of the compressor section in the signal path This enables more flexibility in sound since the compressor will become more sensitive to any frequencies that have been boosted by the EQ section The effect may be compared by toggling the EQ Pre switch Output Gain This controls the level at the Ebony A3output The nominal level is 0dB at the centre detented position This control effectively acts like an output fader and is very useful when recording direct to tape or hard disc through the Ebony A3 You may find that some digital recorders require a good deal of input level in order to register a 0dB reading on their meters 18dBu analogue usually matches OdBFS in the digital domain This is normal since many digital recorders are designed to preserve headroom and keep the signal well below the OdB clip point thus preventing the 16 recorder distorting The Ebony A3 provides a further 15dB of gain at the output fader to drive digital recorders It is important to distinguish the difference between the output gain knob and the gain make up knob in the compressor section The gain make up control is only active when the compressor is switched on whereas the output gain control is always active but will have no effect on the compression characteristics of the signal Digital Output The digital output is an option for the Ebony A3 The card converts the analogue signal at 24 bit resolution and is selectable to 44 1 or 48
13. eeps the signal path short and of the highest quality No unnecessary console stages are passed through thus maintaining quality Many mixers have sockets called insert points which allow processors such as dynamics devices and EQs to be patched in line into the mixer signal path at various points The mixer s channel insert point usually sends the input signal out directly after the mixers preamp stage allowing connection to the line input of the Ebony A3 and then returns the processed signal from the line output of the Ebony A3 back into the mixer at the same point in the signal path This is commonly achieved using a special insert cable sometimes known as a Y lead or split lead usually a stereo 0 25 jack connector at one end split into two mono jack or XLR connectors one for send and one for return The most likely positions that insert points are located on a mixer are in the channel group and stereo master sections Patching the Ebony A3 into the channel insert point means that any signal passing through that channel will pass directly though the Ebony A3 Compressing an off tape signal on mixdown for instance can be achieved by connecting the tape machine to the mixer tape returns then connecting the Ebony A3 into the relevant console channel insert point The off tape signal will then be fed into the Ebony A3 s line input via the mixer insert send connection The line output of the Ebony A3 connects b
14. efective materials or workmanship will be repaired free of charge The warranty excludes damage caused by deliberate or accidental misuse tampering 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 record the following details and retain proof of purchase date TL Audio Limited Letchworth England Tel 01462 490600 International 44 1462 490600 Fax 01462 490700 International 44 1462 490700 www tlaudio co uk email info tlaudio co uk 24
15. eve more compression is not but beware some other compressors may work in the opposite direction Ratio Once the input signal has crossed the threshold the degree of gain reduction is determined by the Ratio control The Ratio control is calibrated in decibels and is simply the change in output level that results from a given change in input level An uncompressed signal will have a 1 1 compression ratio every 1dB change in input level results in the same 1dB change in output level A compression ratio of 1 3 for instance means that a 3dB change in input level will only give a 1dB change in output level For more severe compression simply turn up the Ratio control The Ebony A3 offers a wide range of ratios from 1 1 5 gentle compression through to 1 30 limiting Limiting effectively clamps the input signal at the threshold level no matter how much the signal is increased this can be useful when trying to ensure that the signal doesn t exceed a certain level for instance to prevent a digital recorder distorting through overload Attack and Release The Attack time sets how quickly the compression is applied once the threshold has been exceeded and the Release time sets how quickly the compression is released and the signal returns to normal once the signal drops back below the threshold The Ebony A3 Attack and Release controls each allow a choice of 2 switched positions either Slow or Fast The speed of the A
16. ically allowing the engineer to get on with more productive jobs Many instruments and voices have a very wide dynamic range that need to be controlled A singer for instance may be singing quietly one moment and very loudly the next and unless compression is applied the vocal sit correctly in the mix in addition to the problems of distortion on loud passages and noise on quiet ones Compressors effectively turn down the loud bits and turn up the quiet bits to achieve a more even and controllable level Compressors are often judged by their ability to control the dynamics without creating noticeable audible side effects Heavy compression can cause the signal to pump or breathe with the onset and release of the compression Some compressor designs can dull the signal and lose the top end of the signal The Ebony A3 is also capable of more severe compression based around the optional Hard Knee mode if this is desired There are other benefits of compression as well as just controlling the peaks and raising the quiet parts applied properly it can add punch and excitement to music as well as fattening up sounds and creating a more professional sounding recording With the Ebony A3 you have pristine Discrete Class A audio with the added benefit of a valve stage that can be activated into the input stage of the signal path this then offers a warmth clarity and presence just not obtainable with solid state or digital products
17. input level increases If the input gain is adjusted the threshold can be re adjusted accordingly to maintain a similar amount of compression Microphone Input When using the Ebony A3 with a microphone source care should be taken not to apply too much gain at the input Start with the input gain control set to minimum and the output master at the mid point 12 o clock position The input gain can then be gradually increased until the VU meter registers about OVU on normal signal level when set to read IN The master output level should then be adjusted to produce the required output CAUTION Never switch phantom power on or off or plug unplug a microphone with phantom power applied unless the output level controls turned down Failure to do so may result in a thump in your monitor loudspeakers or PA system Line Input A line level signal should already be at about the correct operating level but monitoring the level on the output meter with the compressor bypassed and the output gain at 04 could check this The input gain should be adjusted until the meter reads about OVU at normal audio level when set to read IN Instrument Input The front panel instrument input socket is suitable for low level sources such as hi impedance microphones pick ups or passive guitars and higher level sources such as active guitars and keyboards as it is switchable to high or low sensitivity 11 30dB Pad Occasionally
18. ith high quality conversion A combination of supreme quality unrivalled sound and stylish aesthetics this range offers superior analogue processing to accompany a digital world The Ebony Series A3 Processor is a single channel unit accepting mic line and instrument inputs Processing includes gain and phase control compression and equalisation A tube stage may be switched into the signal path with variable drive control The block diagram of the processor is shown in fig 1 A discrete Class A electronically balanced mic input amplifier is used delivering superior audio performance with very low noise low distortion and wide bandwidth The mic input is suitable for low impedance 150 600 ohm microphones with a gain control range of 16 to 60dB Front panel switches provide 48V phantom power and 30dB pad for high output mic applications The front panel mounted jack socket is suitable for a variety of sources including electric guitar acoustic pickup and keyboard The instrument input has high low switching and a dedicated valve input stage Phase reverse and high pass filter switches are provided affecting whichever of the mic line and instrument inputs are selected The tube stage has a variable drive control with the signal level indicated by the variable intensity Drive LED and Peak LED Use of this feature typically introduces 1 to 10 harmonic distortion predominately second harmonic without changing the
19. kHz sample rates The digital connector is a coaxial SPDIF format on an RCA phono type connector The card also has a word clock BNC connector for clocking to an external digital source This is useful for slaving the Ebony A3 A D card to an existing digital setup without the Ebony A3 needing to be the digital master in the system Output Peak LED An output Peak LED is provided adjacent to the VU meter The LED complements the average reading VU meter and is useful for monitoring the output prior to sending to a DAW for example The Peak LED illuminates at an output level of 19dBu 17 GETTING STARTED Connections There are various ways that the Ebony A3 can be connected into your audio system The three most common are a As an instrument front end b Connected to a channel insert point on a mixing desk c Connected to a group or master insert point on a mixing desk To use the Ebony A3 as an instrument front end connect the output of the Ebony A3 directly to the line not mic input of your console recorder or sound card A common mistake is to plug the Ebony A3 line output into the XLR mic input of a console This will cause the console mic inputs to overload very easily and may result in a loss of quality Once the output is connected simply feed your mic or instrument into the relevant input on the Ebony A3 Recording direct to the multitrack recorder thus bypassing the console is a common technique these days as it k
20. mic or line signals the signal ground may be obtained by linking pins 1 and 3 in the mating XLR connector Do not leave pin 3 open circuit as this may result in a loss of level and or increased noise Good quality screened cable should be used particularly for microphone or low level sources to prevent hum or noise pickup Instrument Inputs A 2 pin mono jack plug is required which should be wired as follows Tip Signal Phase or hot Screen Ground Insertion Point The insertion point is balanced with separate TRS jacks for send and return 3 pin TRS jack plugs should be used wired as follows Tip Signal Phase or hot Ring Signal Non Phase or cold Screen Ground Unbalanced equipment may be interfaced with the processor insertion point by wiring the plugs with ring and screen connected together The insertion point is half normalled i e a plug inserted into the Send socket will provide an additional signal output without breaking the signal flow within the processor When a plug is inserted into the Return socket however the internal signal is interrupted and replaced with the insertion return signal Output The output is via balanced 3 pin male XLR connector The mating connector should be wired as follows Pin 1 Ground screen Pin 2 Signal Phase or hot Pin 3 Signal Non Phase or cold
21. nob to select the centre frequency and is variable between 150Hz and 7KHz Remember that there is a good deal of gain available from the EQ section and greatly boosting one or more bands can cause the red Peak LED to illuminate as the Ebony A3 is driven towards clipping In this case you need to compensate by bringing down the Ebony A3 output gain control until the Peak LED is extinguished 15 LF Band The LF Low Frequency band of the equalizer has a shelving characteristic i e it extends from the selected frequency to the extreme low frequency limit of the equaliser s response The cut or boost is controlled by a continuously variable centre dented rotary knob up to 15dB of cut and boost is available The slope of the shelf is 12dB octave Mid Band The Mid Frequency band has a peaking characteristic i e it boosts or cuts a section of the audio spectrum around its selected centre frequency only A rotary switch from 150Hz to 7kHz selects the centre frequency of the Mid band The mid band possesses a fairly low Q value of approximately 0 5 for a response which results in effective equalisation without harshness HF Band The HF High Frequency band has a shelving characteristic complimenting the LF band The centre frequency is at 12kHz EQ On The EQ On switch allows the EQ section to be bypassed for comparison of the equalised and original unprocessed signal EQ Pre The EQ Pre switch places th
22. nt 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 Tube Stage Drive and Peak LEDs These LEDs indicate the drive level to the tube or valve stage The Drive LED is a variable intensity indicator starting to glow when the tube harmonic distortion is around 1 and being fully illuminated at approximately 5 harmonic distortion The distortion is predominately second harmonic unless very high drive levels are used in which case the tube is eventually pushed into harsher saturation indicated by the tube Peak LED What is Compression Compression is an essential but often misunderstood process in modern recording Put simply compression reduces the difference between the loudest and the quietest levels 12 of an audio signal This is known as reducing the dynamic range of that signal and is a powerful tool for an engineer helping to avoid overloading distortion problems as well as raising the level of the quieter parts of the audio signal Before the introduction of compressors the only way this could be achieved was by gain riding whereby an engineer would control the fader manually in order to try and anticipate very large levels which might distort the signal or very low levels which may get lost in noise The introduction of compression devices meant that this process could be controlled automat
23. or EQ and gatestages switched out start with the Ebony input gain at minimum and output gain at OdB 2 Gradually bring up the Ebony A3 input gain until the Drive LED illuminates with the chosen source material this should also generate a healthy reading on the Ebony A3 VU meter when set to I P Then switch to meter O P and check that around OVU is being produced and adjust the output level control if necessary 3 Try engaging the 30dB pad and 90Hz filter switches You should notice that the pad greatly reduces the mic gain and the filter reduces the LF response of the mic try those B and P letter sounds as outlined in operation section 4 Now depress the Compressor On switch and using the compressor controls you will need to adjust settings to suit the instrument you are listening to A good starting point is set the Attack and Release to Fast Ratio to 1 3 Knee to Soft and Threshold to 20dB 5 As you start turning the Threshold control clockwise towards 0dB the Ebony meter should now register that some gain reduction is taking place Aim to get around a maximum 3 4dB of gain reduction occurring as a starting point by lowering the Threshold further if necessary You should also notice that increasing the Ratio setting causes more gain reduction to occur 6 When gain reduction is taking place you should notice that the output level is reduced By switching the compressor in
24. output level from the unit The tube stage can be selected or bypassed as required The Compressor has continuously variable threshold ratio and gain make up and switched settings for hard or soft knee and fast or slow attack and release times The Equaliser has 3 bands The HF and LF controls are shelving whilst the mid control is a swept peaking filter Comprehensive switching via relays allows the A3 to be configured with the equaliser pre or post the compressor or with the equaliser in the sidechain for de essing or frequency variable compressor effects A VU meter is provided which can be selected to either input or output signals It may also be selected to display the compressor Gain Reduction In this mode the meter normally indicates OdB falling back as the signal is compressed The amount of compression may be read directly from the dB scale The meter is also provided with a 10dB switch which keeps the reading on the scale when driving a high level out to a DAW for example In the 10 mode OVU is calibrated as 14dBu out Why Class A Class A circuits are designed with a constant current flowing through all of the transistors which is sufficient to drive the peak output required from each block of the circuit This ensures that every transistor is kept at its optimum operating point minimising non linearities due to changes in current and internal thermal effects and eliminating the objectionable cross ove
25. pression the overall signal level will be reduced when gain reduction is taking place The Gain Make Up control is designed to boost the compressed signal by between 0 and 20dB in order to bring back the level to the same loudness as the uncompressed signal Without this control comparing the original and compressed signals becomes difficult since there would be a level drop each time the compressor is switched in therefore it is normal to adjust the Gain Make Up control so that when the compressor on switch is activated the audio signal remains constant in level Unlike the Output Level control the Gain Make Up control is active only when the compressor on switch is engaged Once the Gain Make Up has been adjusted use the Output Level control to set the overall output level of the Ebony A3 Compressor On This switch enables or disables the compressor stage thus allowing an A B comparison to be made between the original untreated signal and the compressed signal Any gain make up applied to the signal only becomes active when the Compressor On is enabled An associated status LED indicates when the compressor is active The Gain Reduction on the VU meter will monitor the level of compression regardless of the compressor stage being active or non active Equalisation The Ebony A3 equalizer section has three bands each with a continuously variable cut and boost control up to plus minus 15dB The mid band has a rotary k
26. r distortion typical of class AB circuits Due to the higher steady state or quiescent currents used the power dissipation of class A circuits is substantially higher than can in general be handled by integrated circuits It is also possible to design discrete transistor circuits to operate at higher voltage rails than are available for audio integrated circuits adding the benefit of greater headroom and improved dynamic range For these reasons there are no integrated circuits in the audio paths of the Ebony Series The outstanding audio quality is reflected in the technical specification of the units with particularly low noise and distortion and wide frequency response Why Tubes Valves or Tubes have long been associated with excellent audio quality recognised as adding warmth or depth to a signal Driving the valves harder results in an increasing level of mainly second harmonic distortion which is responsible for the characteristic overdriven valve sound The Ebony Series feature variable drive valve circuits which may be switched into the audio paths or bypassed completely The valve drive control varies the signal level through the valve stage without affecting the overall gain from input to output It is therefore possible to vary to the degree of harmonics added by the valve from subtle warming to crunchy overdrive with a single control The signal level through the valve is displayed by the
27. s XLR s or TRS jack plugs carrying the phase and non phase signals plus a screening ground connection Naturally the Ebony Series features balanced ground free signals for all line inputs and outputs as well as insertion points where present The range is also compatible with unbalanced equipment as described above Please read this manual fully before installing or operating the Processor BLOCK DIAGRAM PRECAUTIONS The T L Audio Ebony Series units require 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 mains operating voltage stated on the rear panel is correct 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 unit is fitted with an internationally approved 3 pin IEC connector A mating socket with power cord and mains plug is supplied All mains wiring should be performed by a qualified electrician with all power switched off and the earth connection must be used Please note that when using this unit with alternate supply voltages in foreign countries
28. se 10Hz to 40KHz 0 1dB 40dB gain Distortion THD Noise 0 035 20Hz to 20KHz 40dB gain Noise EIN 127dBu unweighted 22Hz to 22KHz 150 ohm source termination Line Input Discrete Class A circuitry from input to output unless Tube stage In Gain Range 20dB to 20dB Maximum Input level 26dBu Frequency Response 10Hz to 35KHz 0 1dB Distortion THD Noise 0 03 20Hz to 40KHz Noise 85dBu 22Hz to 22KHz OdB gain at input and output Instrument Input Tube input stage plus discrete Class A circuitry to output Gain Range 8dB to 40dB High 10dB to 22dB Low Input Impedance High 70Kohm Low High Pass Filter 3dB 90Hz second order 21 Insertion Point Pre Compressor and EQ Balanced separate Send and Return TRS jack sockets Nominal Level OdBu Noise 85dBu 22Hz to 22KHz Output Maximum Gain 15dB Maximum Level 22dBu 2Kohm load 26dBu 10Kohm load Noise at minimum gain 90dBu 22Hz to 22KHz Tube Stage Typical Distortion 1 to 10 depending on Drive level predominately second harmonic Noise 80dBu 22Hz to 22KHz output gain OdB Compressor Threshold Range 20dB to 10dB Ratio Range 2 1 to 20 1 Attack 11 Fast 8ms Slow Release 200ms Fast 2s Slow Knee Hard and Soft settings Gain Make Up 0dB to 20dB Equaliser LF 1
29. ttack and Release should in general be able to work with the tempo of the signal For example if the signal is a snare drum by monitoring the gain reduction it is possible to set the Release to allow the compression to fully recover i e the gain reduction needle will settle back to 0dB before the next snare beat This prevents the second snare beat being reduced in level in comparison to the first One side effect of having an incorrect release setting is distortion on low frequency signals which can particularly occur when using a fast release setting on bass heavy signals the compressor is forced in and out of compression during one cycle of the waveform and distortion results The Ebony A3 has a built in Hold facility which delays the onset of release for approximately 10mS after the input signal falls below the threshold A slow release time should be used if distortion is still experienced 14 Knee The Knee switch enables the Ebony A3 to be operated in two different modes soft Knee or hard Knee Soft knee mode offers a gentle compression curve around the threshold point and is traditionally employed to yield a more subtle musical type of compression effect The hard knee setting causes the full compression ratio to be applied immediately the signal has passed the threshold point so tends to produce more pronounced and severe compression Gain Make Up While the subjective sound quality of the signal can be improved by com
30. when using sensitive condenser microphones the source signal may be too loud for the input preamp In this situation to avoid any overloading or distortion of the mic preamp stage the 30dB pad can be used to reduce the input gain to a more manageable level The 30dB pad only applies to the microphone input 90Hz Filter The high pass filter switch restricts the low frequency response of the preamp to effectively remove rumble of LF noise from the signal The filter can be useful in restricting popping on vocals or even low frequencies caused by contact with microphone stands or microphone cables Popping is an undesirable thump that is caused by close miking certain spoken or sung letters namely P or B These particular letters cause a sudden expulsion of air that can result in an audible thump As this thump has a lot of low frequency content the high pass filter can help to reduce the problem as can using a pop filter a device usually made out of nylon material similar to stockings suspended in front of the microphone The 90Hz filter is active on the mic line and instrument inputs Phantom Power 48V phantom power is available at the mic socket selected by a front switch Phantom power should only be used in conjunction with suitable microphones CAUTION Operation of the phantom power switch or plugging a microphone in or out with phantom power applied may cause a click or thump in your loudspeakers To preve
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