One night in 1981, a rock band was setting up a large rack of new Perreaux amps. Being an Australian I was impressed by this fresh New Zealand product with good presentation and build quality, that sounded fine too. The sound tech was telling me the amps had a reputation that in the heat of the show if the musician or roadie accidently knocked a can of beer over them, they would keep on going as the case design had no holes. Being quite a change from other amps with cooling holes. I learnt Perreaux had a HiFi version of these amps and this interested me big time.

PERREAUX POWER AMPS

POWER AMPS All Amps DESCRIPTION Pro 8000B 5000B (6 page brouchure) Pro 2000B HiFi 2150B (200 W/Ch) (Detailed below) 1993-94 Amplifiers 2400 3400 5570  Perreaux Philosophy

PMF 3150 Large (300W/Ch) 3150 Specs

	SM2 PRE AMP 1982 to 1985 SM2 Large 1 SM2 Specs		SM3 PRE AMP SM3 Large1 SM3 Specs 2
	SA35 PRE AMP with TONE CONTROLS SA35 Large SA35 Rear	SM5	The SM2 & SM3 had advanced phono stages adjustable with resistor plugs, also had no tone controls. The SA35 features tone controls, or via a switch bypassed for straight thru signalling. Depending on quality of recording, it usually sounds a bit better with tone control on, with off being a bit uninvolving on pop and rock. I have owned both the SM2 & SA35.

2150B - Class AB 1982 to 1985 The Perreaux 2150B is a Hi Fi connoisseur's dream come true ... a power amplifier built without compromise. A power amplifier which will enthuse even the most critical listener. Featuring 200 watts minimum RMS per channel into 80hms from 20Hz to 20kHz at no more than 0.009% total harmonic distortion. The Perreaux 2150B's purity of sound is unmatched by any other power amplifier in the world today. 2150B SPECS Brouchure Specs Manual Specs (pages 1, 12)     The 2150B was built from 1982 to 1985. The power amp is Class AB. Each channel has 3x 50mA / FETs giving a bias current or idle current of 150mA per channel (too low for Class A). At idle, power draw from powerpoint would be around 55W. The big transformer gives a lovely tonal quality to the Perreaux sound. Often missed in other brands.

2150B UNDERSIDE HiFi 1150B rear

2150B TOPSIDE

MODIFICATION Front switch replaced with step start

Main switch Issues: Background: The huge 2150B transformer primary draws a lot of current during switch on, the room lights even dim for a finite time. During switching, the risk of arcing across the contacts is high, leading to a shortened switch life. A 10nF 600V capacitor was tried across the switch terminals but this had little long term effect. From new, the original press button switch lasted approx 8 years, the heavy duty replacement about 3 years then replaced at intervals after that. The FIX - Step Start of Perreaux power amp: The instant the power amp is switched ON, the transformer primary is energised via a 22 Ohm 10W power resistor, thus limiting any in-rush current to a safe value. At the same time, the power relay coil is energised, but due to mechanical inertia, the contacts close some 5 to 10ms later, with a reassuring click sound, bridging out the resistor, and providing full mains voltage to the transformer. The small time delay in powering the transformer fully takes the peak "edge" off any in-rush current, thus protecting the power switch and input fuse from premature failure. The mains switch and the (paralleled) power relay contacts are bridged with 47nF 600V Capacitors to suppress any contact arcing. An option to a mechanical relay is a solid state relay (SSR) which can be substituted directly (without the click 0n sound), but with a higher cost penalty (~$60+). The problem that is being solved here is minimising the power supply initial in-rush current which stresses the mains power switch, which ultimately fails. The problem comes about from the fact that the switch on is random, and if it occurs when a mains cycle is near maximum, the peak current can be very high. Using a SSR that features "Zero Crossing" switching (sometimes referred to as "Zero Voltage"), controls the inrush current automatically by only turning on at the beginning of a mains power cycle (when the voltage is zero), thus eliminating the need for a "step-start" and associated power resistor. All relays, including SSRs, are available with 240V AC control operation. There is no "low voltage" involved. The original mains power switch just switches mains power to the relay to activate it.

TU3 Large Pic TU3 SPECS

If you can assist with model info or your experiences from this era please email Anthony

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