User Instructions

IMPORTANT! Read before operating this equipment!
CAUTION: The exclamation mark is to draw your attention to important instructions and safety procedures in this manual. ATTENTION: The lightning flash warns you of the risk of electrical shock presented by components inside this product. Unauthorised personnel must not open this unit. WARNING: To reduce the risk of electrical shock do not remove any unit covers or panels. There are no user serviceable parts in this product. WARNING: To reduce the risk of electric shock, do not expose this equipment to rain or moisture. HEED WARNINGS: All warnings on the product and in the operating instructions should be adhered to. READ ALL THE INSTRUCTIONS: All the safety and operating instructions should be read before the product is operated. RETAIN INSTRUCTIONS: The safety and operating instructions should be retained for future reference. FOLLOW INSTRUCTIONS: All operating and use instructions should be followed. CLEANING: Unplug this product from the mains before cleaning. Do not use liquid or aerosol cleaners. Use a damp cloth for cleaning. WATER AND MOISTURE: Do not use this product near water - for example, near a bath tub, wash bowl, kitchen sink, or laundry tub, in a wet basement; or near a swimming pool and the like. The product must not be exposed to dripping or splashing and no objects filled with liquids, such as vases, shall be placed on the product. HEAT: The product should be situated away from heat sources such as BLANK PAGE radiators, stoves, or any other products (including amplifiers) that produce heat. VENTILATION: Slots and openings in the cabinet are provided for ventilation, to ensure reliable operation of the product and to protect it from overheating and these openings must not be blocked or covered. The openings should never be blocked by placing the product on a bed, sofa, rug or similar surface. This product should not be placed in a built-in installation such as a bookcase or rack unless proper ventilation is provided or the manufacturer's instructions have been adhered to. OBJECT OR LIQUID ENTRY: Never push objects of any kind into this product through openings as they may touch dangerous voltage points or short-out parts that could result in a fire or electric shock. ACCESSORIES: Do not place this product on an unstable cart, stand, tripod, bracket, or table. The product may fall, causing serious injury to a child or adult, and serious damage to the product. Use only with a cart, stand, tripod, bracket or table recommended by the manufacturer, or sold with the product. Any mounting of the product should follow the manufacturer's instructions, and should use a mounting accessory recommended by the manufacturer. ATTACHMENTS: Do not use attachments not recommended by the product manufacturer as they may cause hazards. MOVING THE PRODUCT: A product and cart combination should be moved with care. Sudden stops, excessive force, and uneven surfaces may cause the product and cart to overturn. POWER SOURCES: This product should be operated only from the type of power source indicated on the marking label. If you are not sure of the type of power supply to your home, consult your product dealer or local power company. For products intended to operate from battery power, or other sources, refer to the operating instructions.
Cyrus 6 Power, 8 Power & X Power
OVERLOADING Never overload wall outlets, extension cords, or integral convenience receptacles. This can result in an increased risk of fire or electric shock.
POWER CORD PROTECTION: Power supply cords should be routed so that they are not likely to be walked on or pinched by items placed upon or against them, paying particular attention to cords at plugs, convenience receptacles, and the point where they exit from the product. NAKED FLAMES: No naked flame sources, such as candles, must be placed on this product. LIGHTNING: For added protection for this product during a lightning storm, or when it is left unattended or unused for long periods of time, unplug it from the wall outlet and disconnect the antenna or cable system. This will prevent damage to the product due to lightning and power-line surges. CAUTION! POLARISED CONNECTOR (CANADA and USA): To prevent electrical shock, match wide blade of plug to wide slot, fully insert. Do not alter or remove this plug if it does not fit your mains power socket. Have a suitable socket installed by a competent electrician.

For product service or technical advice, contact only authorised Cyrus service centres. The Cyrus distributors are listed at the end of this instruction manual

POWER SUPPLY:

Connect the moulded IEC connector of the AC cord supplied plugs into the power inlet 1@ on the rear of the unit. The mains fuse 1# is on the rear panel next to the power switch. It must only be replaced as follows: X Power X Power 8 Power, 6 Power 8 Power U.K. / Europe 230V..T2AL/250V 20mm N. America 115V.T3.15AL/250V 20mm U.K. / Europe 230V..T1AL/250V 20mm N. America 115V.T1.6AL/250V 20mm
The mains supply requirement for your Cyrus 6/8/X Power is marked on a label on the rear panel. Before connecting, check that this voltage is the same as your mains supply. 230V Products: 115V Products: Voltage Range Voltage Range 220V-240V 110V-120V
If you move to an area with a different mains voltage, contact your local Cyrus distributor to have your product converted.

NOTE FOR UK CUSTOMERS:

The 6/8/X Power is supplied with a power cable terminated by a fused 13A mains plug. This plug should not be removed but if it is removed, dispose of it safely and do not re-use it. To connect a new 13A plug, proceed as follows: Connect the brown wire to the terminal marked L or coloured red. Connect the blue wire to the terminal marked N or coloured black. The internal plug fuse should be 5A.

SERVICING:

Do not attempt to service this product yourself as opening or removing covers may expose you to dangerous voltage or other hazards. Refer all servicing to qualified service personnel. CONDITIONS REQUIRING SERVICE: Unplug this product from the wall outlet and refer servicing to qualified service personnel when: When the power supply cord or plug is damaged. If liquid has been spilled, or objects have fallen into the product. If the product has been exposed to rain or water. If the product has been dropped or damaged in any way. If the product does not operate normally by following the operating instructions. (Adjust only those controls that are covered by the operating instructions. Improper adjustment of other controls may result in damage requiring extensive work by a qualified technician to restore the product to its normal operation). When the product exhibits a distinct change in performance. REPLACEMENT PARTS: When replacement parts are required, be sure the service technician has used replacements specified by the manufacturer or have the same characteristics as the original part. Unauthorised substitutions may result in fire, electric shock, or other hazards. SAFETY CHECK: Upon completion of any service or repairs to this product, ask the service technician to perform safety checks to determine that the product is in proper operating condition. PRODUCT SERVICE CENTRES

Welcome to the world of Cyrus!
Congratulations on your choice of Cyrus Hi-fi products. Our state-of-the-art design technology and outstanding quality of manufacture has won countless awards around the world. We are confident that you will derive great pleasure from owning a product from one of the most recognised and respected manufacturers of hi-fi equipment. Please read these instructions carefully before commencing installation. They provide full guidance to help you install your Cyrus 6 Power, 8 Power or X Power safely and correctly.

INSTALLATION - 6 Power

Key to the 6 Power rear panel drawing (Fig.1b) 1. Right speaker output + 8. 2. Right speaker output 9. Left speaker output 3. MC-Bus Connection 10. Left speaker output + 4 Right Chain Output 11. 5. Left Chain Output 12. Power Inlet 6. Left Input 13. Mains Fuse 7. Right Input 14. Power Switch
Cyrus 6 Power, 8 Power & X Power model differences
These user instructions refer to the Cyrus 6 Power, Cyrus 8 Power and Cyrus X Power amplifiers. Model differences are indicated in the text where they occur.
Connecting to the AC Mains Supply
Connect the socket on the AC Power cable to the Power inlet 1@ on the rear panel of the 6 Power. Now connect the cable to a suitable AC power point. The mains power switch 1$ on the rear panel of the 6 Power should be left on for normal operation, except when left unattended for a long period when it should be switched off or disconnected from the AC supply.
Preparations for Installation
Before installing the Cyrus 6/8/X Power check that the following items are included in the accessory box. Guarantee Card (back page of instruction manual) Power Cable 2 MC-Bus phono cables 4 speaker plugs (certain markets only) After removing these items, please retain the packing. Install the Cyrus6/8/X Power in a well ventilated location away from sources of high temperature, dust or humidity. Never stand the 6/8/X Power under another unit or on any surface likely to hamper its cooling or ventilation.

Input Connection

Connect a stereo phono interconnect from the output of the preamplifier to the 6 Powers left and right inputs f, g. Be sure to observe colour coding of the plugs to keep left and right channels correctly ordered.

Loudspeaker Connection

Fitting the speaker plugs Check for polarity indicators (+ and -) on the loudspeaker cable and fit the plugs provided. Observe any signal directionality markings indicated on the cable. If an arrow is printed on the cable it should point toward the loudspeaker. If additional or replacement speaker plugs are required for the 6 Power ensure that the correct BFA type are purchased. Loudspeaker connection Connect the left loudspeaker to the rear panel sockets 1) (red speaker plug) and i (black speaker plug) of the 6 Power. Connect the right loudspeaker to the rear panel sockets a (red speaker plug) and b (black speaker plug) of the 6 Power. Dual outputs are provided for the convenient connection of bi-wiring speaker cables. Fig. 4a shows a wiring schematic for a bi-wired system.

Bi-amplification

For convenience of connection in applications such as Bi-Amplification the Chain outputs d, e allow more than one 6 Power to be connected to a PreAmplifier. The Chain facility can be used with two or more 6 Powers for Bi/Tri-amping by connecting the Chain output of the first 6 Power to the inputs of the next 6 Power. Such a system provides the sonic benefits of totally separate power amplification for the bass and treble units of the loudspeakers. When adding additional 6 Powers to a system, connect a quality RCA phono interconnect from the Chain output RCA jacks d, e to the inputs f, g of the new 6 Power. When the input connections to the new amplifier are complete, separate connections may be made to the bass and treble units of the system speakers. Fig. 4c shows a wiring schematic for a bi-amped system.

MC-Bus connection

Connecting the MC-BUS sockets c of the 6 Power in an MC-BUS system provides unified system power control. An MC-BUS loop is established by connecting single phono cables from the MC-BUS output of one unit to the MC-BUS input of another in a daisy-chain. Complete the loop by returning the MC-BUS output of the final component to the MC-BUS input of the first (see example system connections in Fig. 3). With MC-BUS established you can control the power function of the system from the front panel or remote control of the main Cyrus amplifier or Surround Processor.
INSTALLATION - 8 Power & X Power
Key to the 8 Power & X Power rear panel drawing (Fig.1a) 1. Right speaker output + (- Speaker output mono) 2. Right speaker output 3 MC-Bus Connection 4. Right Chain Output 5. Left/Mono Chain Output 6. Left/Mono Input 7. Right Input 8. Stereo/Mono selector switch 9. Left speaker output 10. Left speaker output + (+ Speaker Output mono) 11. PSX-R Connection 12. Power Inlet 13. Mains Fuse 14. Power Switch

Mono input f of the left channel 8/X Power. Connect the right output of the preamplifier to the M Mono input f of the right channel 8/X Power.
Fitting the speaker plugs Check for polarity indicators (+ and -) on the loudspeaker cable and fit the plugs. Observe any signal directionality markings indicated on the cable. If an arrow is printed on the cable it should point toward the loudspeaker. Two channel stereo speaker connections Connect the left loudspeaker to the rear panel sockets 1) (red speaker plug) and i (black speaker plug) of the 8/X Power. Connect the right loudspeaker to the rear panel sockets a (red speaker plug) and b (black speaker plug) of the 8/X Power. Dual outputs are provided for the convenient connection of bi-wiring speaker cables. Figure 4a shows a wiring schematic for a bi-wired stereo system. Single channel mono speaker connections Connect the left loudspeaker to the left 8/X Power using the panel sockets marked M+ 1) (red speaker plug) and M- a (black speaker plug). Repeat this procedure to connect the right channel speaker to the right channel 8/X Power. Fig 4b shows a wiring schematic for a bi-wired system using mono amplifiers. Audio-Visual multi-channel systems Connect each 8/X Power in turn to the system speakers, following the two channel or single channel instructions above, as appropriate.
Connect the socket on the AC Power cable to the Power inlet 1@ on the rear panel of the 8/X Power. Now connect the cable to a suitable AC power point. The mains power switch 1$ on the rear panel of the 8/X Power should be left on for normal operation, except when left unattended for a long period when it should be switched off or disconnected from the AC supply.
External Regulated Power Supply - PSX-R
The Cyrus PSX-R is a unique DC power supply which will upgrade the sonic performance of your 8/X Power and enhance its current drive. When a 8/X Power/PSX-R combination is installed, analogue and signal related sections are powered from this clean, stable power source while other requirements are supplied internally. This ensures complete isolation of control circuits and sensitive analogue sections reducing AC mains-borne noise and power supply ripple. To connect the PSX-R to the 8/X Power plug the connector on the umbilical cord of the PSX-R into the Multi-Pole socket on the rear of the 8/X Power (1! Fig.1b) You will need a mains supply for both units.
For convenience of connection in applications such as Bi-Amplification the Chain outputs e and d allow more than one 8/X Power to be connected to a Pre-Amplifier. The Chain facility can be used with two or more 8/X Powers for Bi/Tri-amping by connecting the Chain output of the first 8/X Power to the inputs of the next 8/X Power. Such a system provides the sonic benefits of totally separate power amplification for the bass and treble units of the loudspeakers. When adding additional 8/X Powers to a system, connect a quality RCA phono interconnect from the Chain output RCA jacks e and d to the inputs f and g of the new 8/X Power. For single channel (mono) chain installations, connect the M chain output e of each Mono amplifier to the M Mono inputs f of the new amplifiers. When the input connections to the new amplifier are complete, separate connections may be made to the bass and treble units of the system speakers. Fig 4c shows a wiring schematic for a bi-amped system using stereo amplifiers.

Two channel or Single channel high power operation
The Power may be configured as either a two channel (stereo) amplifier or as a single channel (mono) amplifier for higher power applications. The 8/X Power is factory set for stereo operation. Stereo systems Stereo systems may be set up with either a single 8/X Power set for two channel (stereo) operation or twin 8/X Powers set for single channel (mono) operation. Audio-Visual multi-channel systems Both two channel and single channel high power modes may be employed for the multiple channel requirements of audio-visual systems. Two channel and single channel amplifiers may also be mixed in these systems if preferred, for example- three 8/X Power amplifiers set for single channel (mono) operation to drive the Front Left, Right and Centre channels and a single Two channel (stereo) amplifier to drive both the left and right surround channels. Note: Ensure all equipment is disconnected from the power before any connections or disconnections are made.
Connecting the MC-BUS sockets c of the 8/X Power in an MC-BUS system provides unified system power control. An MC-BUS loop is established by connecting single phono cables from the MC-BUS output of one unit to the MC-BUS input of another in a daisy-chain. Complete the loop by returning the MC-BUS output of the final component to the MC-BUS input of the first (see example system connections in Fig.3). With MC-BUS established you can control the power function of the system from the front panel or remote control of the main Cyrus amplifier or Surround Processor.
Two channel (stereo) operation Set the STEREO/MONO switch h to Stereo. Connect a stereo phono interconnect from the output of the preamplifier to the 8/X Power's left and right inputs f and g. Be sure to observe colour coding of the plugs to keep left and right channels correctly ordered. Single channel (mono) operation When switched for single channel mono operation, twin 8/X Power amplifiers are necessary in a stereo system one for the left and one for the right channel. Set the STEREO/MONO switch h on both amplifiers to Mono. Connect a single phono interconnect from the left output of the preamplifier to the M
OPERATION - 6 Power, 8 Power & X Power
Key to the front panel drawing (Fig.2) 1. 2. 3. Standby Switch Standby Light Mono Light (8 Power & X Power only)

TROUBLESHOOTING GUIDE

If your 6/8/X Power is not operating properly, disconnect the power and check all connections using the notes in this manual. If problems persist, the checklists below may help. If you are in any doubt, consult your dealer. No sound from either speaker Preamplifier mute switch is on Loudspeakers are disconnected Fault indication on the front panel of your 6/8/X Power No sound from one loudspeaker Does your speaker have fuses? Speaker cables or interconnects faulty Mono installations: Check speaker, replace fuses Check connections, cables - replace if needed Check connections are correct to input and output of both amplifiers. Set the switch to stereo Deselect Mute Check speaker connections See Fault Indication System

Switching On

The mains power switch 1$ on the rear panel of the 6/8/X Power should be left on for normal operation, except when left unattended for a long period when it should be switched off or disconnected from the AC supply. When power is applied, the STANDBY key a may be used for power control. The Standby light b shows red when the 6/8/X Power is in Standby and green when operational. In addition to manual power control from the STANDBY key, the 6/8/X Power also features a music sensing automatic power control which listens for the presence of an input signal and will switch on if music begins to play. If the 6/8/X Power has been activated in this way it will reset to Standby five minutes after the music has stopped. Remote power control can also be enabled by connecting the MC-Bus sockets c of the 6/8/X Power to a Cyrus system which includes a Preamplifier, Integrated amplifier or Surround decoder. A number of 6/8/X Powers may be connected in this way to provide remote standby control of all the system power amplifiers.
Poor quality sound in two channel stereo mode (8/X Power) Selector switch incorrectly set to mono Selector switch incorrectly set to stereo Speakers plugs not connected to the correct terminals
Poor quality sound in single channel mono mode (8/X Power) Set the switch to mono Check all carefully speaker connections
Disabling the Music Sensor
In some installations a number of 6/8/X Power amplifiers may be driven from a single preamplifier source to feed loudspeakers in several extension rooms. In systems such as these it may be preferable to disable the Music Sensor to prevent all amplifiers switching on when music commences. The user can disable the Music Sensor by holding the front panel Standby key whilst switching on the unit at the rear. The amplifier will now respond only to the front panel standby button and MC-Bus commands. The Music Sensor will remain disabled until power is next disconnected from the unit. The Music Sensor may also be permanently disabled by returning the 6/8/X Power to your retailer or the Cyrus factory for an internal adjustment. NOTE:- If MC-Bus connections are made to the 6/8/X Power the music sensor is disabled automatically.

FAULT INDICATION SYSTEM

The 6/8/X Power has a powerful protection system and fault indication system designed to prevent damage to your hi-fi system and help you diagnose a possible problem. If a fault persists, reset the amplifier via the rear panel mains switch.

FAULT INDICATIONS

Standby light flashing Green / Yellow This indicates overload in at least one channel. If the problem is temporary (e.g. excessive volume), normal operation will resume after ten seconds. If the fault indication persists, there may be a problem with the speakers or connections. Standby light flashing Green A fault has been reported from the PSX-R (8/X Power) Switch off the power at the rear panel and unplug the speaker cables. If the fault indication clears when power is re-applied, check the loudspeakers, cables and plugs for loose strands of wire causing a possible short circuit.

FRONT PANEL INDICATORS 8 Power & X Power
MONO Indicator The MONO Indicator c will glow red if the rear panel STEREO/MONO switch h is set for MONO Operation. This switch can be operated only when the 8/X Power is in Standby. Operating it at any other time activates the fault indication system.
The PSX-R is disconnected or switched off. (8/X Power) Standby light flashing Yellow / Red The 6/8/X Power has over heated.
Switch off the power to the 8/X Power and the PSX-R Switch on again. If the problem does not clear, return both units to your Cyrus distributor for checking. Check there is power to the PSX-R and check the PSX-R connection to the 8/X Power. Check the ventilation around the 6/8/X Power. Allow the unit to cool down before re-applying power. Return the switch to its original position.
MONO light flashing (8/X Power) The STEREO/MONO switch has been changed whilst the amplifier is operating.
If after taking remedial measures a fault condition remains, you should return the 6/8/X Power to your Cyrus appointed dealer or an authorised Service Centre.

SPECIFICATIONS

Power Supply Voltage:... As plate on rear of unit Power Consumption Standby.... 6W ON (No Load).... 16W Max...6 Power.. 300W 8 Power.. 300W X Power.. 360W EMC & Safety Compliance (230V)...CE EMC & Safety Compliance (115V).. FCC, cCSAus Enclosure Dimensions (WxHxD)... 215 x 75 x 365mm Weight..6 Power.. 4.3Kg 8 Power.. 4.3Kg X Power.. 5.6Kg Material...Die cast chassis

WARRANTY

The warranty card enclosed should be completed by the Dealer and the purchaser and returned to CYRUS or its Distributor within 8 days of purchase. No Dealer or Distributor may vary the terms of this warranty which is personal to the original Purchaser and is not transferable. Please retain the sales receipt as proof of purchase. Warranty claims must wherever possible be made through the Dealer from whom the equipment was purchased. This warranty excludes: Damage caused through neglect, accident, misuse, wear and tear, or through incorrect installation, adjustment or repair by unauthorised personnel. Any unauthorised servicing will result in loss of guarantee. Liability for damage or loss occurring in transit to or from the purchaser. Consequential damage, loss or injury, arising from or in conjunction with this equipment. Equipment for attention under warranty should be consigned return carriage paid. If returned equipment is found to comply with the published specification, CYRUS reserves the right to raise a charge. The above conditions do not affect your statutory rights as a consumer.

Audio Performance 6 Power
Input Sensitivity (50W/8 )... 381mV Input Impedance.... 20k Channel Balance... 0.1dB Frequency Response..-3dB.0.2Hz-100kHz Signal to Noise Ratio (A-WTD).Unwtd.. 107dB (Ref 50W) A-wtd. 114dB Signal to Noise Ratio (A-WTD).Unwtd.. 90dB (Ref 1W) A-wtd.. 97dB Output Power...8 Ohms. 50W THD+N (@ 2/3 full power).20Hz-20kHz.. 0.01% 1kHz.. 0.0015%
Audio Performance 8 Power
Input Sensitivity (60W/8 )... 413mV Input Impedance.... 20k Channel Balance... 0.1dB Frequency Response..-3dB.0.1Hz-100kHz Signal to Noise Ratio (A-WTD).Unwtd.. 108dB (Ref 60W) A-wtd. 115dB Signal to Noise Ratio (A-WTD).Unwtd.. 90dB (Ref 1W)...A-wtd.. 97dB Output Power Stereo (Internal PSU).8 Ohms. 60W Output Power Mono (Internal PSU)..8 Ohms.. 110W Output Power Mono (with PSX-R).8 Ohms.. 125W THD+N (@ 2/3 full power).20Hz-20kHz.. 0.01% 1kHz.. 0.0015%
Audio Performance X Power
Input Sensitivity (60W/8 )... 413mV Input Impedance.... 20k Channel Balance... 0.1dB Frequency Response..-3dB.0.1Hz-100kHz Signal to Noise Ratio (A-WTD).Unwtd.. 108dB (Ref 60W) A-wtd. 115dB Signal to Noise Ratio (A-WTD).Unwtd.. 90dB (Ref 1W) A-wtd.. 97dB Output Power Stereo (Internal PSU).8 Ohms. 70W Output Power Mono (Internal PSU)..8 Ohms.. 120W Output Power Mono (with PSX-R).8 Ohms.. 130W THD+N (@ 2/3 full power).20Hz-20kHz.. 0.01% 1kHz.. 0.0015%
Cyrus reserves the right to change specifications without notice. E&OE.

PRODUCT INFORMATION GUIDE
Cyrus Mono X Power Amplifier

Construction

Enclosure Material Cyrus Inverted die-cast chassis Lightweight non-magnetic magnesium alloy RCA phono or XLR balanced Bi-wire Loudspeakers (BFA terminals) RCA Chain out 330VA Toroidal transformer MC-BusTM System Bus 150W (into 8 Ohms) 240W (into 4 Ohms) 1500W <0.004%, (1kHz into 8 Ohms) -3 dB at 0.5Hz and 130kHz 700V/S (filters bypassed) 80 Amps peak to peak 380mV (for 50W into 8 Ohms) 660mV (for 150W into 8 Ohms) 775mV (for 50W into 8 Ohms) 1.3V (for 150W into 8 Ohms) 19k (RCA), 20k (BAL) 660mV (for 660mV RCA or 1.3V BAL input) 114dBA 73 x 215 x 360 (mm), 2.8 x 8.4 x14.1 (inches) 5.5kg Quartz or Brushed Black

Electrical

Inputs Outputs Power Supply Communications

Specifications

Continuous Power Burst Peak Power Distortion Frequency Response Slew rate Max output Current Sensitivity (RCA input) Sensitivity (RCA input) Sensitivity (BAL input) Sensitivity (BAL input) Input impedance Chain Output voltage S/N ratio Dimensions (H x W x D) Weight Finish

Features

Unique 'Zero feedback' topology Separate voltage and current amplifiers Conservative 150W continuous rms rating (8) Massive peak power output RCA/BAL input options Fully buffered Chain output Fully mapped over-current protection Extensive use of Star-Earthing technique Non-magnetic lightweight die-cast chassis MC-BusTM System Bus

Benefits

- Inherently natural, high resolution musical reproduction. - Exceptional load tolerance, drive power and finesse. - A set of Mono X amplifiers comfortably exceeds the power rating of most multi-channel AV amplifiers. - Dynamic power capability which can satisfy the most demanding of Home Theatre systems and program material. - Flexibility of installation. - Easy Bi/Tri amping. - For pure, safe 80A pk to pk current delivery. - Enhanced low level resolution. - Interference-free low-resonance enclosure. - Integrated system control with the Cyrus range.

Setting Up

Run in for at least 48 Hours before serious listening. Use Cyrus Interconnects. Match with a Cyrus pre-amplifier for optimum performance.
Cyrus Mono X Design Brief
The X-series has been the most demanding product range developed to date by Cyrus. Over many months the team applied their established skills in taking a technically excellent amplifer design, and through incremental listening tests worked to achieve a natural and extended soundstage with outstanding bandwidth. From the inclusion of massive, over-engineered linear power supplies through to the selection of specialist coupling components designed specifically for use in high-end amplifiers, the Pre X/Mono X amplifier system is the first X-series statement from Cyrus. The Mono X power amplifier is packed with a long list of features including the famous Cyrus zerofeedback circuit topology (delivering outstanding power with exceptional load tolerance), a massive power supply with many stages of voltage regulation and a sophisticated computer control system offering intelligent circuit protection, convection control to maintain the temperature of the amplifier within safe limits and local bus communications with other Cyrus components.
The harmonic distortion character of the Mono X is closely aligned to the response of the human ear. As output level reduces to lower levels where the ear becomes most sensitive to these effects, the distortion produced by the Mono X falls below measurable limits. The result is exceptional musical resolution. The graph below shows that the Mono X's inherently linear circuits produce negligible distortion at low powers.
AUDIO PRECISION FFTTHD-F AMP1(dBr) vs FREQ(Hz) 0.JAN 98 08:57:27

-30.00

-60.00

-90.00

-120.0

-150.1k 10k 20k

Fig 1: FFT plot of distortion at 1kHz 0.01W into 8ohms
Power amplifiers have two primary tasks - i.e. voltage and current amplification of the input signal, to provide a large and powerful signal for the loudspeaker. Traditionally, in most power amplifiers, these functions are combined into one overall circuit topology. The Mono X splits these functions into dedicated circuits - the input voltage gain amplifier and the output current amplifier. The voltage gain amplifier uses a zero feedback complementary bootstrap cascoded 'class A' buffer which drives a precision resistor. The current developed in driving the resistor is mirrored in to another precision resistor which is 52 times greater in resistance. The voltage developed across the second resistor is 52 times greater, hence voltage gain. This voltage gain operation is buffered by a second zero feedback complementary bootstrap cascoded 'class A' buffer. The current amplifier is an error corrected bipolar emitter follower designed to drive equally well into all impedances. In the Mono X neither of these stages have any global feedback. The current amplifier completely isolates the precision voltage amplifier from the loading effects of the speaker. This arrangement enables the Mono X to preserve fine detail, even under the most arduous of dynamic conditions. The unique cooling system of the Mono X includes a variable speed fan to supplement the thermal performance of the Cyrus casting. At low listening levels the substantial heatsinks of the Cyrus casting are adequate to naturally cool the amplifier, so the fan is switched completely off and will not disturb the listener. As the output power increases with higher listening levels, the amplifier will warm up and the fan begins to run slowly, but only during louder passages in the music. At very high listening levels, the fan speed is increased to maximum, but again only whilst the music is playing. This ensures that the cooling noise from the fan will never intrude into the dramatic silences which occur in music performances.

The custom 330VA ultra-low noise transformer, dual bridge rectification blocks and high current output devices endow the amplifier with great reserves of power. The Mono X not only delivers 150W RMS into 8Ohms and 240W into 4Ohms but can also deliver transient power of over 1500W pk into a low impedance. The transformer uses pairs of coils wound in anti-phase to each other, common mode noise from rectifier circuits (that change AC power into DC power) now cancels out in the transformer core. Twin rectifiers are used in the power supply reducing the effects of high charging currents imprinting noise onto the low noise ground system. A high voltage, fully regulated power supply is employed for the voltage amplifier preventing power supply modulation imprints from reaching the sensitive low-level circuitry. This virtually eliminates all traces of mains related harmonics on the amplifier output. The Chaining feature and consistent gain structure of the Mono X facilitates easy bi-amping or triamping of a fuller installation. The micro-processor control system of the Mono X, in keeping with other Cyrus components, provides a powerful interface to other Cyrus products as well as an intelligent, fast acting protection system. The over current protection circuit has a mapped 'current trip level' verses 'time' characteristic. This allows the amplifier to operate to the secure maximum i.e. pulses of 80A pk-pk while sustained high currents will not blow the main PSU fuses. The unique MC-Bus connectivity of the Mono X is in keeping with the total system approach of the Cyrus range of products. This facility enhances ergonomic operation of the unit in a system context. Total automation of the test, alignment and calibration of Cyrus Mono X is facilitated via the MC-Bus during its manufacturing process, eliminating potential human error. The quality lightweight die-cast enclosure of Cyrus Mono X has a myriad of advantages both electrically and mechanically. The integrated heatsink design enhances the thermal efficiency allowing higher performance to size ratio. Additionally, the non-resonant nature of the alloy minimises microphonic effects, while its non-ferrous composition provides an effective shield from external electro-magnetic disturbances. This also eliminates coupling of the power transformer stray magnetic fields to the sensitive audio circuitry.

Why Zero Feedback?

Negative feedback was first implemented by Mr Harold S. Black of Western Electric in the late 1920's. Its role was to reduce harmonic and frequency distortions in telephone lines, particularly over longer distances, where several in-line repeater amplifiers would cause non-linearities to be compounded. Negative feedback is essentially a high power servo system and works by constantly comparing an amplifiers output signal with its input signal. Correction is then applied to reduce distortion errors found in the output signal. For feedback to work correctly the amplifier must have an excess of gain, and the amount can vary enormously - anywhere between 10 and 10,000,000. The more gain then the more powerful the error reduction. The theory is very powerful and has become indispensable for many applications, however, when used for audio power amplifiers great care must be taken and compromises must inevitably be made. The designer has to balance low and high frequency linearity, stability and slew rate while being totally reliant on feedback for frequency response, damping factor and DC off-set. Through its evolutionary years Cyrus has investigated all of these principles. Early research into low and zero feedback designs indicated that an amplifier free of the compromises of global negative feedback could bring multiple benefits in sonic performance. Our development of ultra-high linearity precision analogue circuits coupled with advanced semiconductor technology imparts Mono X with all of the unique sonic qualities associated with low and zero feedback designs. However, technical performance of our zero-feedback circuitry remains uncompromised posting harmonic and frequency distortion levels that shame most conventional feedback designs. Furthermore, loop in-stability is totally removed, propagation delays have less significance because the input does not depend upon the output for comparison and the speaker is isolated from the voltage gain stages.