Prisma 350 Stereo Power Amplifier

The Prisma 350 is a 350W per-channel stereo power amplifier. The high power output allows the 350 to effortlessly drive any loudspeakers with the precision, detail and authority that Perreaux products are renowned for.

The ability to extend deep into the lower octaves with control and finesse delivers instruments and voices with lifelike heft, body and scale. Sonic transparency is deep at the heart of the 350, allowing the musicians artistic prowess to be realised in its entirety and as intended by the mastering engineer. As with all Perreaux products, the design is completely solid state, featuring the finest audiophile grade componentry throughout.

General Features

Rugged Build Quality

Mechanical strength has been a hallmark of Perreaux products since the company first started production back in 1974. The concept behind the physical design and construction is that each structural member should contribute to both rigidity and performance.

Ultra Stiff Power Supply

The 350 incorporates a massive custom designed, toroidal power transformer, employing unusually heavy gauge wire that reduces copper losses to a minimum. An electrostatic shield prevents AC line borne interference from entering the signal path. The power supply filter capacitors, totaling 60,000uF (30,000uF per channel), have exceptionally low inductance and internal resistance. They charge and discharge in response to load demand far more rapidly than conventional storage capacitors and are capable of delivering the instantaneous current required by the output stages, providing optimum dynamic range and transient response. The wiring from the power supplies to the output boards is designed for unimpeded transmission of the required current and voltage and utilizes heavy gauge, tinned copper wire cables. Since power supply leads radiate at signal frequencies, all wiring is carefully loomed to minimise this effect.

Hybrid Class-A/AB

The bi-polar transistors used in the 350 are operating in Class-A. This avoids the crossover notch distortion and the resulting odd-order harmonics present, to some degree, in all other classes of operation. The devices used in the 350 output stage are MOSFETs, which with high quiescent current circuitry, are run in the equivalent of Class-A to 10 watts. Beyond this point the output class is technically Class AB (hence the hybrid nomenclature), but with a major difference. The combination of MOSFET characteristics and their application in this circuitry, result in crossover distortion so minimal that it is virtually non-existent.

MOSFET Output Stage

The 350 output stage takes full advantage of the unique qualities of MOSFET devices and in many ways they are superior to bi-polar transistors. A major advantage is their tendency to draw less current over a large section of the power bandwidth as their temperature rises (Negative Temperature Coefficient), hence self stabilising thermally, whereas bi-polar transistors draw more current as their temperature rises (Positive Temperature Coefficient) and protection circuits become mandatory to prevent thermal runaway and eventual self destruction. MOSFETs have the ability to swing fully across the amplifier’s internal DC voltage and are therefore true "rail-to-rail" devices. Using MOSFETs encourages the highest performance from the balance of the internal amplifier circuitry.

Multiple Protection Systems

The 350 incorporates a full range of protection circuits, isolated from all signal carrying circuits via opto-couplers. However, these circuits are aimed at ensuring an extremely high safety margin for these high-powered products rather than as a mandatory addition to correct for poor or overloaded circuit topologies.

Earthing

We pay particular attention to designing the product to ensure maximum separation between internal signal and power earths, only meeting at a central starred point.

Highest Quality PCBs and Components

Quality fiberglass PCBs, featuring heavy copper tracks and high-grade components, are used throughout the 350.

Bi-Wiring Made Easy

2 pairs of binding posts per channel make bi-wiring speakers as simple as "A-B-C".

User Controls

Balanced/Unbalanced Input Select
Rear Mounted Power Switch
Earth Isolation Switch

I/O Compliment

1 pair Unbalanced Inputs (RCA)
1 pair Balanced Inputs (XLR)
2 pairs Speaker Binding Posts per channel
2 Remote Trigger Inputs (5VDC)
Continuous Power Ouput (per channel): 350Wrms into 8Ω
  600Wrms into 4Ω
Total Harmonic Distortion (THD+N):  
  Typically 0.004% @ 1kHz into 8Ω
  20Hz to 20kHz <0.02% into 8Ω
Frequency Response: 20Hz-25kHz, ±0.25dB
Hum & Noise (unweighted): -100dB, ref. rated output
Dynamic Headroom (rated with music): >1.1dB
Maximum Current Output: 80A per channel
Damping Factor: >700 @ 1kHz into 8Ω
Gain 30.7dB
Input Impedance:  
  Unbalanced 22kΩ
  Balanced 3.3kΩ
Input Sensitivity:  
  Unbalanced 1.5Vrms
  Balanced ±0.78Vrms
Dimensions:
  Width
  Height
  Depth

430mm (16.9")
186mm (7.3")
497mm (19.6")
Weight: 30.0kg (66.1lb)