Two-Channel
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Two-Channel
Our most powerful reference two channel amplifier has been designed and built to deliver the best possible Hi-Res audio performance from any high-quality passive loudspeaker system.
Its low-feedback construction provides ultra-low distortion, ensuring an unparalleled level of clarity and transparency across the audible range.
Bridgeable to over 1.5Kw, the Meridian 857 features a totally new design for a Meridian power amplifier, borne out of extensive research, experience and a thorough understanding of psychoacoustic principles.
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Reference 857
The Meridian 857 is a Reference Two-Channel Power Amplifier delivering 500W per channel into 4Ω. This Hi-Res Audio amplifier, bridgeable to >1.5KW, is available as a dedicated rack-mount variant and incorporates a totally new design based upon extensive research. Tremendously powerful with an incredibly low noise floor, the Meridian 857 represents a step change in amplifier design.
In normal mode, delivers 2 x 250 watts into 8 ohms and 500 watts into 4 ohms; continuously on both channels. In bridged mode, delivers 1 x >1 kilowatt into 8 ohms and 1 x >1.5 kilowatts into 4 ohms.
Low-feedback construction provides ultra-low distortion, ensuring an unparalleled level of clarity and transparency across its full frequency response of 1-100kHz (-/+ 2dB).
The signal path is balanced throughout - fed from either the XLR balanced inputs or from the "SuperBal" circuitry which converts unbalanced (single-ended) signals to balanced audio as soon as they enter the amplifier.
Non-ferrous chassis and panels – aluminium construction for magnetic linearity. Transformer including five secondary windings for maximum isolation between low-power and high-power circuitry. Ground plane design with multilayer circuit boards optimised for signal handling.
The open-loop characteristics of an amplifier are crucial to its sound quality. The power amplifier design is intrinsically linear and uses error correction in the output stage to provide low open-loop output impedance. This allows the power amplifier to achieve impeccable measured performance and a high damping factor while only applying modest amounts of negative feedback.
Both channels feature two pairs of binding-posts on their outputs to facilitate bi-wiring of loudspeakers with two sets of connection terminals.
The Meridian 800 Series represents the pinnacle of technological audio innovation and, most importantly, designed and engineered to provide you with the most rewarding personal listening experience possible.
Available in over 270 different colour finishes and backed by a five-year warranty, the 857 Power Amplifier allows you to achieve the optimum performance from any passive speaker system resulting in sound quality which will satisfy the most discerning of listeners.
Here you will find a quick overview of the product highlights and features.
Here you will find a summary of the complete range of Meridian products in one document.
AUDIO INPUTS
Two XLR balanced inputs
Two RCA unbalanced inputs
AUDIO OUTPUTS
250W RMS into 8 Ohms per channel both channels driven
500W RMS into 4 Ohms per channel both channels driven
Bridgeable to >1KW RMS into 8 Ohms • Bridgeable to >1.5KW RMS into 4 Ohms
4 WBT terminals per side allow bi-wiring
CONTROL SIGNALS
Trigger input [3.5mm 5-30 VDC]
COOLING
High level of passive cooling for silent in-room running
Six variable speed fans maintain amp functionality if hostile thermal conditions encountered in rack
DISPLAY
Backlit touch sensitive logo changes colour to indicate amplifier’s status
‘Standby’ [BLUE], ‘Normal Operation’ [GREEN]’, ‘Fans Active’ [AMBER], ‘Overload’ [RED]
DIMENSIONS
HEIGHT:
175mm [6.9in] without feet
195mm [7.7in] with feet
WIDTH:
480mm [18.9in]
DEPTH:
Standalone 445mm [17.6in]
Rack-mount 425mm [16.8in]
WEIGHT:
Standalone 32kg [70.5lbs]
Rack-mount 35kg [77.1lbs]
CONSTRUCTION
Black finish in aluminium and glass
Dedicated Rack-mount variant (4U high)
Custom Meridian Select colours also available
POWER
Advanced linear power supply: 100V ac 50/60 Hz | 110-120V ac 50/60Hz | 220-240V ac 50/60Hz
It can deliver both channels simultaneously each with 250W into 8Ω and 500W into 4Ω.
In bridged mode, the 857 can deliver 1kW into 8Ω and 1.5kW into 4Ω.
The front-panel indicator will show blue.
Touch the logo on the front-panel. After a four second start-up period, the amplifier will switch on and the indicator will show green.
Yes. Touching the logo on the front-panel for about four seconds while the amplifier is running blanks the indicator. Touching the logo for four seconds again will bring the indicator back on.
If the temperature within the case of the amplifier reaches 65ºC, the fans begin to operate slowly. If the temperature reaches 75ºC, the fans run at regular speed and the indicator on the front-panel shows amber.
The front-panel indicator shows red, the outputs are muted and the fans operate. Once the amplifier has cooled down, the amplifier will unmute.
Under certain fault-conditions, the amplifier protects itself by switching off. This can be caused by the presence of DC voltage on an input or by short-circuiting an output. Once the problem has been removed, the amplifier can be reset by turning the power at the back-panel off then on again.
The 'Bridge Mode Select' switch should be set to 'On' and the two negative speaker terminals must be connected together. This can be done with the bridge-mode link supplied with the amplifier or by using a short length of speaker cable of appropriate thickness.
The amplifier can be brought out of Standby by applying any DC voltage from 5V to 30V to the trigger input.
Check the 'Bridge Mode Select' switch is set to 'Off'. If the switch is inadvertently switched to 'On', the amplifier’s left input is amplified normally, but the right channel input is ignored. Instead, an inverted version of the left input is fed to the right channel of the amplifier. This causes the sound from the amplifier to suffer as described.
Check the 'Input selector' switches are set appropriately. If set incorrectly, no sound will be produced by the channel(s) concerned.
If the option is available, it is generally advisable to use balanced connections. The science behind balanced connections offers the potential for improved performance by achieving lower levels of noise on the input signal. Even if the sonic difference between the two types of connection is not overly apparent during casual listening tests, it can be reassuring to know that 'best-practice' has been observed.
There are two approaches to adding a second amplifier. The two amplifiers can be used in 'bridged' mode to provide more power to each loudspeaker. Although the output of the amplifiers is not improved in itself, the extra power can be beneficial when used with some loudspeaker designs. Or, if the loudspeakers are capable of being connected in a 'bi-amp' arrangement, this can be done. Bi-amping gives each amplifier channel a simpler load to drive. This can improve sound-quality with many loudspeaker designs.
The output impedance is 0.024Ω at 1kHz rising to 0.153Ω at 20kHz.