User manual TAG MCLAREN AUDIO 250X3R

owner's manual contents version V3.10 | 01 12/01 02 04 06 07 08 15 20 21 24 25 26 27 29 controls welcome introduction construction amplifier module set up operation remote control TAGtronic Communications Bus running in and warming up care and maintenance appendix technical data 250x3R 9340D 02 | controls controls | 03 three channel status LEDs remote control active LED remote control window TAGtronic communications bus balanced input sockets line level input sockets RIGHT CHANNEL BUS IN OUT CENTRE CHANNEL LEFT CHANNEL LINE INPUT LINE INPUT LINE INPUT Double insulated: When servicing, use only identical replacement parts. CAUTION RISK OF ELECTRIC SHOCK RISK OF ELECTRIC SHOCK DO NOT OPEN NOT OPEN DO BALANCED INPUT clas s 2 w i r i ng minimum rated load impedance 8 per channel 2 1 3 2 1 3 BALANCED INPUT 2 1 3 2 1 3 BALANCED INPUT 2 1 3 2 1 3 220-240V ~ 50-60Hz Fuse; T1A L250V + ­ ­ ground + ­ ­ ground + ­ ­ ground + LOUDSPEAKER OUTPUT LOUDSPEAKER OUTPUT + LOUDSPEAKER OUTPUT + ­­ ­­ three channel amplifier 250x3R s made in United Kingdom serial number ­­ three channel amplifier 250x3R s power/ standby LED power button mute LED ac supply socket and fuse carrier loudspeaker terminals Specification shown may var y for different countries 04 | welcome welcome | 05 welcome to Dr. Udo Zucker Chief Executive Officer TAG McLaren Audio TAG McLaren Audio exists with one aim in mind: to produce the very best audio and audio-visual equipment. Like many people, I often have my best ideas when relaxing to a piece of music or watching a movie. For years, knowing the technical capabilities of TAG McLaren, I have nurtured the ambition to push music and movie reproduction to the absolute limit without compromising ease of use; that's why we formed TAG McLaren Audio. At the core of our development team are highly experienced engineers whose heritage of award-winning hi-fi and worldbeating electronic control systems is envied by many and equalled by few. There are many immediate spin-offs into audio from `a perfect team' Pushing technological boundaries; TAG McLaren's F1 electronics our expertise in automotive electronics, mechanical engineering and the material science of Formula One motor racing: multilayer printed circuits, fast digital signal processing, electronic noise suppression, radio frequency technology and software expertise to name but a few, all prerequisites of an outstanding audio product. TAG McLaren's aim is sonic perfection combined with aesthetic delight and solid build quality ­ a rare combination in hi-fi but one which TAG McLaren Audio is already delivering. Dr Udo Zucker 06 | introduction Experts have known for many years that precision, clarity, stereo image and depth can be significantly improved by using so called monoblocs or single channel amplifiers. These constructions provide completely independent amplification for each channel which prevents interaction between them, resulting in a cleaner signal and hence better clarity and stereo imaging. This is true with two channels and even more with multi channel amplifiers! The TAG McLaren three channel amplifier 250x3R includes three completely independent amplifiers, one for each channel. They only share the remote and protection control circuitry, located on a separate printed circuit board. This circuitry is powered individually by a tiny transformer construction | 07 and local power supply (as it isn't responsible for any sound performance), allowing the 250x3R to be put into standby without incurring a high energy bill. The remote control circuitry acts on commands received from either the user via the IR remote control or the AV32R via the TAGtronic Communication Bus. Channels can individually be switched on/off for best sound quality and most efficient energy usage. The protection control circuitry monitors the performance of each module against programmed parameters in order to power down a channel should a fault occur. The 250x3R can be equipped with two (250x3R/2) or three amplifier modules, making it suitable for a stereo set-up or as part of a complete home cinema system. Thank you for purchasing the TAG McLaren three channel amplifier 250x3R The 250x3R is a fully remote controlled, very high power, hi-performance amplifier which delivers sound reproduction of outstanding clarity and purity for up to three channels. The 250x3R can be factory assembled with two or three channels. Retrospective upgrade from two to three is possible without losing or compromising quality. The 250x3R achieves typically 255 W per channel into 8 and 400 W into 4 . Its IHF tone burst performance is also impressive: typically 300 W into 8 , 550 W into 4 and 1000 (!) W into 2 . The 250x3R's operating software can be upgraded using a PC and the TAGtronic Programming Cable with new software being distributed via TAG McLaren's website www.tagmclaren.com. Amplifier modules can also be upgraded should better amplifier technology become available in the future. 08 | amplifier module Each module has its own high-efficiency aluminium heatsink for excellent heat dissipation, allowing it to drive even the most critical loudspeakers safely and totally independently from any of the other modules. This results in uncompromised sound quality with perfect channel separation. Each 250x3R module delivers typically 255 Watts into 8 ohms, 400 Watts into 4 ohms and will drive 1000 Watts into 2 ohms for short durations. As a result of the 250x3R`s self-contained amplifier module construction, this performance is wholly independent of the number of channels being driven and thus even during the loudest passages of your favourite movie the soundstage remains stable, controlled and detailed. There are many design features which have been derived from our excellent 100x5R and our F1-600MR amplifiers to make this amplifier very special. We have listed a few of these very technical items on the following pages. an optimised mix of global and local negative feed back The 250x3R gives excellent linearity and low distortion without relying on high global negative feedback, which can present difficulties when handling rapidly-changing signals. The amplifier implements at each amplifying stage a controlled amount of local feedback, which not only linearises but also defines the gain and other vital parameters closely. cascode compensation The 250x3R uses an advanced stabilisation concept called Cascode Compensation. This might be the first time that this sophisticated and elegant system has been used in an audio amplifier. Its advantages are excellent stability, inherently good supply-rail rejection and a reduction in DC drift. This gives outstanding stability with performance drifts being virtually eliminated. output transistors The output devices are bipolar junction transistors chosen for maximum linearity. The advanced MT-200 package is used which gives a greater area for heat transfer than amplifier module the traditional TO3, enhancing the amplifier's reliability for many years to come. | 09 deep under the skin The 250x3R consists of three identical power amplifier modules in a single compact enclosure. Each module is a complete, selfcontained amplifier, with its own power transformer, bridge rectifier, energy storage capacitors and amplification stage, requiring only mains supply and control signals to function. Control signals are used to switch each amplifier module individually on/off and to protect it in case an error condition, such as a short circuit in the loudspeaker, is detected. exceptionally accurate quiescent stability It is universally accepted that accurate setting and stability of quiescent conditions is crucial to optimal Class-B amplifier operation. The bias range over which the best linearity is obtained is narrow, and on either side of it crossover distortion increases markedly. The 250x3R has one of the most accurate quiescent controls ever implemented, stabilising against output level, load impedance and mains voltage changes. sophisticated muting The 250x3R has a sophisticated muting system, which stops you hearing loud, annoying switching noises and protects both the amplifier and the loudspeakers. Particular care has been taken to make sure that the muting circuitry, when switched off, doesn't affect the sound quality. For this purpose carefully selected relays with minimal crosstalk between coil and contacts have been used. 10 | amplifier module coupled without any capacitors, an arrangement called `straight line' technology. The result is a very precise reproduction of the lowest bass. supersonic high frequency response (high end) In order to reproduce high frequencies, the 250x3R is constructed using highly-rated, high-precision components. The circuit has been painstakingly designed to minimise audio signals picking up interference and intermodulating. Exceptional transparency and purity of sound are the result. amplifier module input balanced XLR and standard RCA inputs The 250x3R provides both balanced XLR inputs and standard RCA inputs. There is no need to switch between the two inputs, the 250x3R will automatically sense the input used. single ended RCA input looking at RCA terminal A single ended connection sends, as the name implies, the signal via a two conductor cable, one for the signal and one for the ground (which is usually connected to the screen on one or both ends). The single ended connection is the most commonly used connection type between preamplifiers/av processors and their power amplifiers. It works extremely well, even over long distances, if the output stages of the av processor/preamplifier are of a `low impedance' configuration, such as those in the TAG McLaren AV32R or DPA32R. However, if several products are connected together it is possible for a current to flow | 11 low distortion A theoretically ideal amplifier reproduces sound perfectly over an infinite range of frequencies - starting from well below the audible range and extending far above the capabilities of human hearing. Although sound outside the human hearing range of approximately 20 Hz to 20 kHz cannot be heard, it can significantly distort the quality of music reproduction through an effect which audio engineers call `intermodulation distortion'. This type of distortion moves imperfections that originate outside the hearing range back into the audible frequencies. To minimise this effect, TAG McLaren amplifiers have a frequency response which extends both above and below the range of normal human hearing. straight line technology (low end) An amplifier must respond to very low frequencies but block any Direct Current (DC) to prevent intermodulation distortion. This is traditionally achieved using capacitors, which also block some of the low-frequency signals. In the 250x3R, a feedback circuit eliminates DC offset voltage and allows the signal path to be direct between the ground connections of those units, caused by electro-magnetic interference or ground potential differences. This current is indistinguishable from the signal and hence can become, if severe enough, audible as a hum or buzz. The problem is usually referred to as ground loops. balanced line technology XLR input looking at XLR connection A major advantage of balanced interconnects is the complete suppression of ground-loop problems. Balanced line inputs use 3 conductors, one for the ground and two for the voltage difference between the signal and the ground at the preamplifier/av processor. As a result the balanced input at the amplifier does not respond to the voltage between input and ground, which could be altered by a ground loop, but to the difference between the two conductors carrying the signal. For this system to work well, it is important that the balanced input performs an accurate subtraction of the signals at its 12 | amplifier module output OFHC loudspeaker connections For excellent sound quality the 250x3R uses TAG McLaren's high grade oxygen free high purity copper (OFHC) loudspeaker terminals combined with a new knob made from nonconductive Pocan. Very few companies provide OFHC loudspeaker terminals due to the difficulties of machining solid copper, an unacceptable excuse for TAG McLaren. The knobs for the 250x3R have been manufactured from non conductive Pocan without a metal insert as it was found that this gave the best sonic result, identical to that obtained using an OFHC knob(1) (as used on the TAG McLaren 100x5R). amplifier module when only the best is good enough! | 13 input terminals. The measure of how well it does this is called the `common-mode rejection ratio'. In the 250x3R this is more than 40 dB, or one hundred times, and best of all, this is permanently fixed as it is set by precision resistors rather than by attempting to balance variable semiconductor properties. combining a single ended av processor with the 250x3R It is important to realise that a balanced output on the sending unit, the preamplifier or av processor is not required to gain the benefits of a balanced input. A single ended RCA output is just as good, so long as the unbalanced-to-balanced cable is wired correctly. TAG McLaren provides a special version of its F3-10-ANA, manufactured with an RCA connector at its input and a XLR connector at its output. For more details see www.tagmclaren.com or your authorised TAG McLaren retailer. The Appendix shows how an RCA-XLR analog cable should be wired to provide ground loop hum suppression, as described above. 1. Many small details lead to this exceptional amplifier, some key elements are covered below: premium-grade audio components All components have been carefully selected and auditioned before a decision about their use in the 250x3R was made. For maximum performance ultrastable Vishay metal film resistors and low dielectric loss Wima poly-propylene capacitors have been selected, providing the increased transparency and excellent noise suppression which audiophiles attribute to these components. mixed technology construction With surface mount components for fast digital signal transfer and leaded throughhole components for perfect audio signals, the 250x3R incorporates mixed technology construction to optimise performance. The result is uncompromised sound in a small size. aluminium for performance The complete case, cooling fins and module construction is made from Aluminium instead of commonly used, cheaper mild steel. Aluminium has been used as extensive listening and laboratory tests demonstrated that the stray fields, albeit minimal for a toroidal transformer, were interacting with ferromagnetic material in their vicinity. safety regulations do not allow the use of a OFHC knob due to the very high voltage the 250x3R can achieve at its loudspeaker terminals 14 | amplifier module vibration damping The cover panel is stiffened by formed ribs, then bonded with viscoelastic laminate to provide a low Q panel which provides rapid absorption of externally induced vibrations. set-up preparation | 15 brass instead of steel The bolt holding the heavy transformer has been made from brass instead of steel as this was also found to make a significant difference to the low frequency impact of the amplifier. Higher cost well invested. beauty to last The finned centre section of the three part fascia is machined from a solid aluminium extrusion and is then fine paint finished. To complete the fascia assembly the two extruded end caps are machined, bead blasted and linished to create an even texture which is then chemically brightened and hard black anodised or silver painted. We know you are keen to get your 250x3R working. This section will have you listening as quickly as possible. The controls diagrams located on pages 2 and 3 of this manual will help you find your way around your 250x3R(1). before you start Make sure that all the components of your system are disconnected from the AC supply whenever you change any connection. Please be aware, when the front panel switch is in the off position, this unit is still connected to the mains supply. If this unit is not to be used for some time, withdraw the mains plug from the wall socket outlet. positioning The 250x3R is capable of consuming over 1000 Watts of electrical power during demanding presentations. This results in significant heat being dissipated. · Please ensure that there is adequate ventilation above and below the unit. 1. · The ventilation of the 250x3R should not be impeded by covering the ventilation slots with items such as newspapers, table cloths, curtains etc. · Place the 250x3R on an open flat surface. · Do not use in a cabinet or on a soft surface such as a carpet. · Do not place any other piece of equipment on top of the 250x3R. · Do not place naked flame sources such as lighted candles on the 250x3R. · Do not expose the 250x3R to dripping or splashing liquids. · Do not place objects filled with liquids, such as vases, on or near the 250x3R. safety first To prevent the risk of electric shock follow these instructions carefully. If in doubt consult a qualified electrician. Throughout this instruction manual, bold print indicates the lettering that you will find on the panels of your 250x3R and the Remote Control 16 | set-up av processor or preamplifier connection set-up | 17 power connection Before making any connections ensure the amplifier is switched off(1) and the mains plug is removed from the rear panel power socket You will require an av processor, such as the AV32R or a preamplifier, such as the DPA32R to provide the signals to drive the 250x3R. loudspeaker connection The contacts of the loudspeaker terminals of this amplifier (marked with the lightning symbol) have hazardous live voltages present. If in any doubt, consult a qualified electrician before making connection to these terminals. On the rear panel of the 250x3R you will find three pairs of loudspeaker terminals. Each pair is connected to one of the three power amplifier modules. The terminals are designed to accept high quality 3/8" (10 mm) spade connectors. Use only high quality ready made cables with insulated spade connectors such as the TAG McLaren Audio F3-10-SPK. Ensure that the amplifier has been switched off and the mains plug has been removed from the wall socket before connecting the red (+) terminal of the loudspeaker to the red terminal on the rear panel of the 250x3R. In turn connect the black (­) terminal of the loudspeaker to the black terminal on the 250x3R. When making the connection, ensure that the spade terminal is correctly located and the loudspeaker terminal is fully tightened. 1. The power button is a latching switch. One press will hold it in; the next will release it Make sure the av processor/preamplifier and all connected source units, such as a CD player are switched off and their mains plugs have been removed from the wall sockets. The 250x3R provides single ended line inputs (RCA) and balanced XLR connections for each module. You can mix both connections, say RCA for module left and right, and XLR for module centre. Do not connect XLR and RCA at the same time to any given module as this will cause severe distortion and can damage your equipment. Do not leave an un-terminated cable attached to an unused input. This is likely to degrade the noise performance of the system. 18 | set-up set-up | 19 using the line input (RCA) The signal connection of the RCA input and the XLR are connected internally. Do not connect both connections at the same time as this might damage your equipment! When the RCA input is used the XLR shortening link, connected when you receive the 250x3R from the factory, must be inserted between pin 1 and pin 3 of the XLR input connector. This is necessary to obtain the correct gain and to reduce the noise pickup. If you connect an RCA output of your av processor or preamplifier with the RCA line input of the 250x3R then you should use a hiquality, well screened RCA-RCA audio cable, such as our RCA/RCA F3-10-ANA interconnect. using the balanced input (XLR) The signal connection of the RCA input and the XLR are connected internally. Do not connect both connections at the same time as this might damage your equipment! In order to use the XLR connection you need to remove the XLR shortening plug, if connected. Please store the shortening plug safely for later use. If your are connecting to equipment with balanced outputs then use a high quality XLR-XLR cable, such as our XLR/XLR F3-10-ANA interconnect. how to connect a single ended RCA output to the balanced XLR input If you are connecting to equipment with single ended RCA outputs and you would like to use the balanced XLR input for best ground loop suppression, then use a suitably manufactured RCA/XLR adaptor cable, such as our RCA-XLR F3 10-ANA interconnect. This connection is recommended by TAG McLaren. More details to the cable are found in the Appendix. The signal connection of the RCA input and the XLR are connected internally. Do not connect both connections at the same time as this might damage your equipment! 20 | operation When all three channels have been activated, you should see the three red LEDs softly illuminated(1), showing that all three channels have energised. Then the amplifier is ready to play source material through the system. Raise the volume level at your av processor or preamplifier slowly at first, until sound is replayed through the audio system. Sit back and enjoy! remote control base features The 250x3R is equipped with a sophisticated micro-controller to monitor and control the 250x3R. The performance of this processor, activated by a tiny remote control(1), allows for class leading ergonomics, for example the flexibility to not only mute all channels simultaneously but also to have individual control over each power amplifier module. So if you play CDs in stereo you only need to switch on the left and right channels(2). 1) 2) | 21 power up When you have completed the set-up and have connected all cables between all components, ensure that the volume control on the av processor/preamplifier is set to minimum before reconnecting the mains plugs and switching on all equipment. Make sure you use the mains cable supplied for your 250x3R. switch on Press the power button in. The blue power LED will come on. The three channel status indicators will flash, as the amplifier channels power up sequentially to prevent excessively high current demand from the mains supply. For added convenience TAG McLaren Audio has integrated the main control functions for the av processor AV32R and the dvd player DVD32R. The complete audio-visual system can be started, stopped or muted from the tiny remote control of the 250x3R. confirming operation Whenever the 250x3R receives valid infra red (IR) instructions from the remote control the 250x3R acknowledges by flashing the top LED on the right front panel, above the power button. 250x3R mute The sound output of all channels can be muted using the single `mute amp' button on the remote. This is a toggle action command - one press will mute and a second press will un-mute. When muted the 250x3R has only disconnected the loudspeakers. The amplifier is still running and the sound will be restored instantly when the mute button is pressed again. When the 250x3R is muted the bottom LED on the right front panel, above the power button, will illuminate. 1) if the 250x3R is connected to the AV32R then the AV32R will control the intensity of all LEDs after a few seconds. For details see the AV32R user manual. the remote of the 250x3R is identical to that of the 100x5R, ensuring that both amplifiers can be controlled with the same remote If the AV32R is connected to the 250x3R then the AV32R can do this for you. Details can be found in the AV32R user manual 22 | remote control heading all Pressing the button labelled `all'(1) will switch all three products in and out of standby mode. channel standby The 250x3R allows for switching individual channels into power saving standby mode. To provide this function certain buttons need to be operated in combination. When pressed, the button marked channel - amp will, after a time delay of one second, switch all three channels in and out of standby as described above. Alternatively if you press the button channel - amp followed (within 1 second) by 1, 2, or 3 then only that channel will toggle in and out of standby. To allow the user to switch several modules together in or out of standby press channel - amp immediately followed by any sequential combination of numbers. remote control extended operation The 250x3R remote control allows the convenient control of the major functions of the TAG McLaren Audio av processor AV32R and the dvd player DVD32R. AV32R Two major functions of the AV32R can be controlled: volume Pressing the `+' and `­' buttons adjacent to the `volume' label will increase or decrease the volume of the sound. av input By using either the `+' or `­' buttons adjacent to the label `AV input' the AV32R will step through all available audio and video inputs in sequence. | 23 standby The 250x3R is provided with a `standby' mode. This function will switch off the power supplies of the amplifier module. The control section of the 250x3R remains active to monitor the status of the 250x3R and to wait for a `wake-up' command from the remote control. Pressing the standby amp key on the remote control will `wake-up' the 250x3R. The 250x3R runs through the start up procedure which takes a few seconds before the unit is finally un-muted. For those channels of the 250x3R which are switched to standby mode the individual channel LED will be extinguished. Only the active channel LEDs are illuminated. amp - dvd - av The remote control also allows you to switch the 250x3R amplifier (amp), the dvd player DVD32R (dvd)(1) and the av processor AV32R (av) in and out of standby. 1. DVD32R Two buttons, directly below the label `DVD', allow the user to control the most frequently used functions of the TAG McLaren Audio dvd player DVD32R. play/pause The DVD32R will play the disk, and any subsequent presses will bring the DVD player in and out of pause. stop The replay of a disc will be stopped. Battery disposal: Please consider the environmental aspects of battery disposal. Some battery types are considered as hazardous waste. Please consult your local authority for further information and advice. if connected to the AV32R and linked via the TAGtronic Bus, for details see the AV32R user manual 24 | TAGtronic Communications Bus software updates One of the flexible aspects of the 250x3R is that the micro-controller software is stored in re-programmable FLASH memory. The FLASH can be re-programmed with updated software using a PC suitably connected via the TAGtronic Communications Bus. Details of future upgrades will be published on TAG McLaren's website www.tagmclaren.com running in and warming up optimum performance for many years running in Just like a high quality car, the performance of your 250x3R will improve during the first hours of operation. The electronic components will then have reached and settled down to near perfect specification. warming up Every time you switch on your 250x3R the performance will improve until the components reach their optimum operating temperature. | 25 TAGtronic Communications Bus The 250x3R includes the `multi device' enhanced TAGtronic Communications Bus. This Bus allows the operating system of the 250x3R to be upgraded and enables products equipped with this advanced interface to transfer and share information easily. We recommend connecting the TAGtronic Bus between the av processor AV32R or preamplifier DPA32R and the 250x3R as this will allow the AV32R/DPA32R to conveniently control the amplifier. Details can be found in the user manuals of the DPA32R/AV32R. 26 | care and maintenance cleaning In order to maintain the appearance of your 250x3R, you can clean it as follows: · before cleaning always disconnect your 250x3R from the AC supply; · any grease or dirt on the case may be removed with a soft, lint free dry cloth. Do not use any other solutions. Do not use water or any solvents or abrasives; · take great care not to get any liquid inside the case. If this happens, you should have your 250x3R serviced. appendix about balanced inputs Balanced inputs are an extremely effective way of providing clean signals to an amplifier even when the surrounding conditions are less than ideal. A balanced input has three connections- typically the three pins on an XLR connector. Standard practice is for Pin 1 to be Ground, Pin 2 to be the "hot" or in-phase connection, and Pin 3 to be the "cold" or phase-reversed connection. A major advantage of balanced interconnects is the complete suppression of ground-loop problems. If a ground-loop is present, then mains-frequency currents can flow down the ground of the interconnect between a sending unit and a receiving unit. If the receiving unit has an unbalanced input this noise is indistinguishable from the signal, being effectively added to it, and is heard as a hum or buzz. A balanced input, however, does not respond to the voltage between input and ground, but to the difference of its two inputs. Therefore when the hot and cold connections are made to the sending unit the unwanted voltage that exists on the interconnect ground is ignored. For this system to work well, it is important that the balanced input performs an accurate subtraction of the signals at its two inputs. The measure of how well it does this is called the `common-mode rejection ratio'. In the 250x3R this is more than 40 dB, or one hundred times, and this is permanently fixed as it is set by precision resistors rather than by attempting to balance variable semiconductor properties. | 27 fuses There is a fuse in the power socket on the back of your 250x3R. To change the fuse, unplug the power cable and carefully pull out the fuse carrier drawer(1).The fuse carrier contains a spare fuse; this is the first one that you see when you open the carrier. There are no other user-serviceable parts inside the 250x3R. ser vice The only service you should do to your 250x3R is described on the previous page. All other servicing should only be carried out by one of our authorised service agents. If service is required, please contact your authorised TAG McLaren Audio retailer. If your 250x3R is still under guarantee, please refer to the guarantee card which gives you details on how to claim against the guarantee. Please keep the original packaging and use it whenever your 250x3R is transported. 1 You cannot open the fuse drawer while the plug is in the socket 28 | appendix technical data | 29 It is important to realise that a balanced output on the sending unit is not required to gain the benefits of a balanced input. An unbalanced (typically phono) output is just as good, so long as the unbalanced-to-balanced cable is wired correctly. The figure shows the correct wiring. The important point is that the Cold line is connected to ground at the remote (phono) end, and not at the XLR. Thus the balanced inputs at Pins 2 and 3 see only the voltage at the phono plug itself, and any spurious voltages that may exist on the ground line are ignored. The XLR body, if metal, will have a separate solder tag for making connections to it; do not join this to ground or Cold as this creates an unwanted connection between audio ground and chassis ground, which may affect system performance. HOT COLD GROUND Screen XLR body not connected to pin 1 This section is for those of you who really want to know the `insides' of your 250x3R. You will not miss out on any of the functions or performance of your 250x3R if you choose not to read any further. rated power output IHF toneburst 250 W into rated load impedance (8 ) 300W into 8 Ohm 550W into 4 Ohm 1000W into 2 Ohm (20ms full on, 480ms at -20dB repeated indefinitely) 1.65 V rms input for full rated power (RCA or XLR) input impedance line input (RCA): 10 k nominal balanced input (XLR): 25 kOhm (10 kOhm) nominal on hot (cold) input pins 28.8 dB at 1 kHz Better than 40 dB at 1 kHz gain 3 1 2 Phono plug Screen bonded to ground XLR male balanced input common-mode rejection signal to noise frequency response (-3 dB) greater than 90 dB (relative to 0 dBW) unweighted 0.1 Hz - 150 kHz 30 | technical data frequency response (20 Hz - 20 kHz) total harmonic distortion + noise ± 0.05 dB less than 0.002% @ 1 kHz 250 W into 8 less than 0.05% from 20 Hz to 20 kHz @ 250 W into 8 less than 0.01% from 20 Hz to 10 kHz @ 250 W into 8 non-inverting between any input and output 10 - 35° C polarity (phase) operating temperature range ac supply frequency ac supply voltage 50 - 60 Hz, depending on country 100 V, 110 - 120 V or 220 - 240 V the voltage is marked on the rear of the product less than 2000 W, standby less than 10 W 445 mm wide 139 mm high 352 mm deep power consumption dimensions (including feet, terminals and controls) We reserve the right to alter design and specification without notice. Specification may vary for different countries.