Wednesday, January 1, 2014

Analog Domain The Isis













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 - €15000

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
1x 500W @ 8ohm, 1x 800W @ 4ohm in bridged mono mode
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 M75A – Stereo integrated amplifier, linear analogue volume attenuator, manual control - €14000

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













75D+75P

Isis M75P – Stereo power amplifier - €13500

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





























The Excalibur

Here's how the Isis is different from existing amplifier topologies. The Excalibur circuit bends some rules, and for a good reason.

The figure shows a highly simplified schematic of the Isis output stage. We have named this topology “The Excalibur”, hoping you understand the humor. The obvious difference is that the output devices are connected in a Common Emitter rather than the popular Common Collector configuration. In such a configuration the driving currents flow between the supply rails and ground and not into the load, leading to improved linearity, among other advantages. Despite its obvious advantages, this topology is not popular as it is prone to thermal runaway and self-destruction if conventional bias control is attempted. Our proprietary DX901 hybrid chip featuring our DXDriveTM technology resolves this “minor inconvenience”, allowing us to take full advantage of the benefits of the topology.

One notable advantage of the Excalibur topology is its unrestricted current output capability. The internal resistance of the circuit is essentially zero. There are no “difficult loads” for the Excalibur. The near-zero internal resistance reduces back-EMF induced distortion when driving loudspeakers. Back-EMF created by loudspeakers and its interaction with the output resistance of a power amplifier is one of the significant contributors to overall distortion and is one of the reasons why most designs fail to perform adequately with loudspeakers, especially evident in circuits employing feedback. The Excalibur enables the use of feedback to vastly improve performance, delivering superior sound over conventional or non-NFB designs.

Only the protection circuits limit the 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.












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.

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.



Dual color anodized finish - f.o.c.
Mirror Chrome finish - add €2500

Gallery

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