aPA7.5 - Power Amplifier

Our monobloc power amp provides the ultimate system performance. Cyrus designed Zero-feedback technology and bespoke power supply componentry provides a massive 150watt burst power for truly enthralling dynamic reproduction.

The revised 7.5 version of our powerful monobloc amplifier is ideal for both demanding AV systems and the very finest hi-fi systems. Owners of the aPA7.5  can take advantage of our factory upgrade to full Mono X performance level.

The aPA7 was firmly established as the flagship Cyrus amplifier for three years, the design team have taken time out to re-visit the design and upgrade it with some performance enhancements. The result of this exercise is the aPA7.5 Mono. This amplifier includes all of the characteristics that has made the original aPA7 ‘best in class’ (the famous ‘zero-feedback’ circuit topology, outstanding power and exceptional load tolerance) but with even greater power supply capacity and further extended frequency bandwidth.

A unique zero-feedback amplifier design constitutes the basis of the Cyrus aPA7.5 Mono. This dedicated application of zero-feedback principles, rather than more conventional feedback methods, addresses our belief of amplifying the signal accurately in the first instance. Negative feedback is therefore no longer required to improve circuit linearity. The harmonic distortion character of the aPA7.5 Mono 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 aPA7.5 Mono falls below measurable limits. The result is exceptional musical resolution. The graph below shows that the aPA7.5 Mono's inherently linear circuits produce negligible distortion at low powers.

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 aPA7.5 Mono 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 aPA7.5 Mono 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 aPA7.5 Mono to preserve fine detail, even under the most arduous of dynamic conditions.

Technical Information


Inputs - RCA phono or XLR balanced
Outputs - Twin BFA (bi-wire) connectors, RCA Chain out
Power Supply - 330VA Toroidal transformer
Communications - MC-Bus System Bus


Continuous Power - 150W (into 8 Ohms) 240W (into 4 Ohms)
Burst Peak Power - 1500W
Distortion - <0.004%, (1kHz into 8 Ohms) <0.05%, (20Hz-20kHz into 8 Ohms)
Frequency Response - -3 dB at 0.5Hz and 130kHz
Slew rate - 700V/μS (filters bypassed)
Max output - Current 80 Amps peak to peak
Sensitivity (RCA input) - 380mV (for 50W into 8 Ohms)
Sensitivity (RCA input) - 660mV (for 150W into 8 Ohms)
Sensitivity (BAL input) - 775mV (for 50W into 8 Ohms)
Sensitivity (BAL input) - 1.3V (for 150W into 8 Ohms)
Input impedance - 19Kohm (RCA), 20Kohm (BAL)
Chain Output voltage - 660mV (for 660mV RCA or 1.3V BAL input)
S/N Ratio - 114dBA
Dimensions - (H x W x D) 73 x 215 x 360 (mm)
Weight - 5.5kg
Finish - Silver or Satin Black

Manuals and PDFs

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