Introducing the Isis - Studiokoncept · The Isis is automatically reconfigured upon mode change to provide a higher voltage in stereo mode, thereby achieving the same combined power

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Analog Domain Audio GmbH • Johann-Sebastian-Bach-Str. 38 • D-85591 Vaterstetten, Germany Tel.: + 49 (0) 1520 / 202 5404 • mail: [email protected] • www.analogdomain.eu

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Introducing

The Isis

Isis M75D pictured above

The Isis range of dual channel amplifiers from Analog Domain represents the current state of the art in

linear amplification technology. It is the result of 15+ years experience in high-performance amplifier

circuit design, created to deliver exceptional performance at an attractive price point. The Isis features our recently disclosed proprietary Excalibur circuit. Near-zero distortion, a noise floor

well below the human perceptual threshold and the generous power output capability of the Excalibur give the Isis its ability to amplify signals with extreme resolution and control, raising the enjoyment of

music to an unprecedented level.

The Isis is available in three configurations: two integrated amplifiers and a matching 2-channel power

amplifier, for installations requiring more power in stereo, or for building multi-way systems with frequency splitting, or multi-channel systems:

Isis M75D – Stereo integrated amplifier, stepped analogue volume attenuator, remote control Isis M75A – Stereo integrated amplifier, linear analogue volume attenuator, manual control

Isis M75P – Stereo power amplifier Highlights:

• Extremely stable M7 modular, thick plate aluminum chassis for vibration immunity

• Stereo mode or bridged mono mode

• 2x 250W @ 8ohm, 2x 400W @ 4ohm in stereo mode

• 1x 500W @ 8ohm, 1x 800W @ 4ohm in bridged mono mode

• XLR balanced line inputs, RCA line inputs with individual gain adjustment

• 120+ dB dynamic range, THD+N < -93dB ref. 1W/4Ohm

• Built in slow-acting clipping limiter to protect loudspeakers

• Fully protected against overdrive, overload and short circuits

• 5 year unconditional warranty against defects in materials or workmanship

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Configurations and finishing options

Isis M75D, white top Features:

• Volume control via switched, low-noise discrete resistor matrix

• 96 dB attenuation range in 128 precise steps of 0.75dB

• Stereo mode and bridged mono mode

• 2x 250W @ 8ohm, 2x 400W @ 4ohm in stereo mode, 2ohm capable


• 2x XLR balanced line inputs + 2x RCA line inputs with individual gain adjustment

• 6Vrms input level compatible, 10Vrms max input level

• Pre-out and Main-in connectors for connecting an auxiliary processor or power amp

• High-performance dedicated headphone amplifier

• Full function remote control

Isis M75D, all black

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Isis M75D+M75P combination, white top

Possible configurations with two units, as pictured above: • 4x250W/8 (4x400/4) – 4-way system or 2x 2-way split system

• 2x500W/8 (2x 800W/4) in bridged mono mode – 2-channel high power system

• 2x250W/8 (2x400W/4)+ 1x500W/8 (1x800/4) – 3-way split system

• Source selection, volume and power on/off are managed by the M75D unit

Rear panels (zoom in to view)

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Isis M75A, all black

Features:

• Volume control via precision, long-life potentiometer

• 100’000+ cycles typical potentiometer life expectancy

• Stereo mode and bridged mono mode

• 2x 250W @ 8ohm, 2x 400W @ 4ohm in stereo mode, 2ohm capable


• 2x XLR balanced line inputs + 2x RCA line inputs with individual gain adjustment

• 6Vrms input level compatible, 10Vrms max input level

• Pre-out and Main-in connectors for connecting an auxiliary processor or power amp

• High-performance dedicated headphone amplifier

Isis M75A, white top

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Isis M75A+M75P set, white top Configuration specs – see M75D + M75P combination above

M75A+M75P set, all black

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The Excalibur

The figure below shows a highly simplified schematic of the Isis power amp stage. We have named this

topology “The Excalibur”, knowing you understand the humor ;) The main difference from popular topologies is in the final stage topology - the output devices are connected in a “common emitter” (CE)

rather than the popular “common collector” (CC), also known as emitter follower, Darlington configuration. The drive currents in a CE configuration flow between the supply rails and ground and

not into the load as in CC, leading to improved linearity, among other benefits. Despite its advantages,

the CE topology is not popular as it is prone to thermal runaway and self-destruction if conventional bias control methods are attempted. Our proprietary DXDriveTM technology resolves this “minor

inconvenience”, allowing us to take full advantage of the superior common emitter topology.

One notable advantage of the Excalibur topology is its unrestricted current delivery capability. The internal resistance of the circuit is essentially zero as there is no local current feedback loop in the

signal path. There are no “difficult loads” for the Excalibur. The near-zero internal resistance reduces back-EMV-induced distortion when driving loudspeakers. Back-EMV1 created by loudspeakers and its

interaction with the output resistance of a power amplifier is a significant contributor to overall

distortion and is one of the reasons why most NFB designs fail to perform adequately with real world loudspeakers. The Excalibur uses multi-point negative feedback to vastly improve performance over

conventional NFB or non-NFB designs.

Only protection circuits limit the current output current of the Isis. The protection circuits would disable the output stage if the load attempts to draw current in excess of the safe maximum. Normal operation

resumes automatically when the overload condition is remedied, e.g. when a short circuit is removed.

1 Motion-induced voltage produced by the movement of the voice coil of a loudspeaker in its magnetic field.

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The Isis in bridged mode The Isis in bridged mode is a differential (balanced) amplifier. The popular method of bridging is to feed the input of the inverting side of the bridge from the output of the non-inverting side. This leads

to increased distortion, among other issues.

When the Isis is switched to bridged mode, the balanced inputs of two sides of the bridge are simply

connected in inverse parallel, producing two identical, inverted signals at the outputs. This is possible since channel gain is matched to within 0.1%. There is no loss of performance in bridged mode; in fact

performance improves over single-ended mode as the even harmonic distortion components appear in phase at the load and tend to cancel out.

Secondary voltage management for optimal loading

Most amplifiers operate off a fixed voltage internally. When a typical stereo amplifier is switched from

single-ended mode to bridged mode, the voltage output doubles relative to single-ended mode as the load is connected across the two outputs. Power output quadruples for the same load relative to single-

ended (stereo) mode. If the power supply were sized for bridged mode, it would limit the power output of the amp in stereo mode, as the supply voltage would be lower than is required for nominal power

output. If it were sized for nominal output in stereo mode, it would be overloaded in bridged mode.

The Isis is automatically reconfigured upon mode change to provide a higher voltage in stereo mode,

thereby achieving the same combined power output as in bridged mode. The full output capacity of the power supply is available to the power stages in either mode without risk of overloading. While such a

voltage changeover is desired, it is practically unachievable with conventional circuits - any change to

the supply voltage typically causes DC offset, bias drift and degradation of performance, and catastrophic failure in some cases.

The Excalibur circuit features our proprietary DXDriveTM bias control technology that maintains optimum

bias and zero DC offset regardless of supply voltage, allowing the Isis to deliver nominal performance in single-ended and in bridged mode.

CPU control and EMI

Internal logic and remote control functionality in the Isis M75D is performed by a high-reliability automotive grade microcontroller. Digital signals produce electromagnetic interference (EMI) due to the

fast switching between logic states. To keep EMI to an absolute minimum, all drive circuits in the Isis

feature slew rate limiting. Furthermore, when the microcontroller is idle it is completely shut down, including its system clock. Operation resumes upon an internal event, if a front panel button is pressed,

or if a command is received from the remote control. The front panel display will illuminate briefly to show the operating status and will shut down in a few seconds, reducing EMI to zero.

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Pricing and availability

The official launch of the Isis will take pace at the upcoming High End Show in Munich, 15-18 May 2014. Units will be available for review in late February 2014. Commercial deliveries will start from

March 2014.

List prices, EUR, EXW, Incoterms 2010* Isis M75D, remote control ......................................................................................................14’990.-

Isis M75A, manual control ......................................................................................................13’990.- Isis M75P dual channel power stage........................................................................................13’490.-

Dual color anodized finish........................................................................................................... f.o.c.

Mirror Chrome finish .........................................................................................................add 2’500.- * MSRP. Subject to local duties and VAT/sales tax. ADA reserves the right to adjust prices without prior notice.

Packaging: reinforced 5-ply carton, 560x560x200mm. Gross weight: approx 27kg.

Specifications*

Parameter Condition Isis M75D Isis M75A Isis M75P

8 ohm, sine wave, rms 250W

4 ohm, sine wave, rms 400W 8 ohm, bridged, music material 500W

Power output

4 ohm, bridged, music material 1000W Damping factor 1kHz, 4ohm load, single-ended > 1000

1kHz, 4ohm, bridged mode > 500 THD+N 20kHz BW, 8ohm, nom. power < 0.002% < 0.002% < 0.001%

THD+N 20kHz BW, 4ohm, 1W output < -93dBr < -93dBr < -95dBr

Power bandwidth 2 ohm, THD<0.1% 5Hz-50kHz Peak current - 50A

Noise output 20kHz BW, rms < 35uV < 35uV < 25uV Dimensions, mm Including feet and rear handles 440W x 454D x 123H

Net weight ~25kg * Preliminary data based on measurements of pre-production prototypes, subject to improvement. ADA reserves the right to change specifications without prior notice.

© 2013. ALL RIGHTS RESERVED. Trademarks and logos are the property of their respective owners. E&OE.

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Introducing the Isis - Studiokoncept · The Isis is automatically reconfigured upon mode change to provide a higher voltage in stereo mode, thereby achieving the same combined power