Hafler P3000 Power Amplifier

Not quite the unloved stepchildren of pro audio equipment, power amplifiers are something that we either take for granted when they are functioning normally, or berate mercilessly when they fail. As we know full well, malfunctioning power amplifiers have the potential to completely fry speaker systems; drivers have been known to quite literally combust. Equally destructive, but more subtle are amps that color the sound, adding a touch of brightness here, or a pinch of depth reduction there. These amps cause mixes to skew off of course, or can lead to ear fatigue after hours of usage. Now that I’ve exposed the dark seamy underbelly of power amps, lets take a look at an amp that is designed to avoid the aforementioned pitfalls.

The product
The Hafler P3000 transnova amplifier is located in the middle power range of the Hafler line, rated for 150 watts per channel output into an 8 ohm load, 200 watts per channel into a 4 ohm load, and for monaural usage 400 watts into an 8 ohm load. The amp uses Hafler’s transnova topology which is a patented application of MOSFET output transistors. Benefits such as a simplified and shortened signal path as compared with conventional MOSFET implementation are claimed as a result. The internal construction utilizes surface mount technology on the two modular channels circuit boards. In the event of a failure the channel’s board may be swapped out by a service center by simply disconnecting the module from the heatsink, power transformer, and binding posts. The P3000 features a sensing circuit that will effect shut down in case of overheating or short circuit, preventing damage either to itself or equipment downstream. A soft-start feature is also included to eliminate the risk of speaker damage due to start-up transient.

The P3000 is two rack spaces in height and conforms to standard rack width. The case of the P3000 is unusual in its design as the rack ears and heat sinks are one-piece (per side) units that are attached to the amplifier chassis. While there are perforations in the top and bottom panels of the amplifier that allow for some ventilation of the internal circuitry, the heat sinks are essential to the operation of the P3000 since it relies upon convection cooling, shunning the use of an internal fan. The manual details the proper provisions to take, should one choose to rack mount the amplifier in order to provide adequate ventilation. In some installations an external fan may be required. The overall effect of picking up the P3000 is somewhat akin to hefting a cinder block, as the amplifier feels very solidly put together and is somewhat heavier than one would expect from its appearance.

The front panel features a lighted power switch towards the center right of the faceplate. Flanking the power switch on both sides are a series of four LED indicators, which indicate the presence of audio signal, amplifier clipping, thermal fault, and the presence of a short circuit. The LED’s are mirror imaged, but at somewhat different heights on the faceplate. On the edge of the faceplate are level potentiometers for each channel. These are calibrated (though unstepped) to perform a maximum of 15 dB of attenuation. The manual recommends leaving the level controls set to the maximum ( 0 dB attenuation) in most installations. I found this to work well with the output from my Neotek IIIc console.

The rear panel includes the now ubiquitous Neutrik dual functioning combination jacks which allow for either XLR balanced or ¼” TS or TRS unbalanced connection. Screened upon the back panel are diagrams showing the correct wiring of both types of connectors (pin 2 is hot). I wish all manufacturers would do this! Binding posts will accept up to 12 AWG wire, or banana plugs of the single or dual variety. Also on the back panel is a sliding switch to select two channel or bridged operation, a socket for a standard 3 wire power cord, and an easily accessible fuse. The weight of the amplifier is 23 pounds. The P3000 is made in the USA, and carries a five-year warranty.

In Use
I used the P3000 mainly as a monitor amplifier in my control room, but I also gave it a try driving a stereo Marshall 4×12 cabinet.

Monitor amplifier – The first thing that I noticed about the Hafler was that it was extremely quiet. The amplifier is almost free from any mechanical noise generated by the transformer, and since it is convection cooled, there is no whirring fan to contend with. The self-noise of the Hafler also seem to be extremely low (the manual states a 100dB signal to noise ratio). The sound of the Hafler was the antithesis of the “solid state” sound that audiophiles love to hate. As opposed to being etched or forward sounding, the Hafler has a realistic and un-hyped spectral and soundstage balance. The P3000 also seems to be free of the image instability commonly referred to as MOSFET mist, which is sometimes a byproduct of amplifiers that use MOSFET (rather than bipolar transistor) output stages. The Hafler is free from the annoying sonic artifacts that seem to plague amplifiers that are obviously built to a price, or are underbuilt for their rated power output. I would add that I tried the Hafler with a few different monitors, ranging from some up-to-date highly efficient models all the way down to a pair of Auratones, with good results.

Guitar amp usage – I used the P3000 to drive a Marshall 4×12 loaded with Celestion 70 watt speakers. Driving the P3000 was a late 1980’s vintage Marshall 9001 tube preamp. I found that the Hafler was a pretty sweet amplifier for use in a guitar rack system. It had a much smoother sound than the PA amp class of amplifier that I have normally used. For players that enjoy jazz or country type clean sounds, the Hafler is a much better bet than a lower grade power amp. Thrash players may prefer something more aggressive and grungy sounding. So be it!

The P3000 is a solid performer, and very easy to recommend to anyone who is in need of a medium powered, good sounding amplifier. While it certainly belongs in the studio, it held its own performing tasks that one would not normally expect a studio grade amplifier to comfortably perform. Thumbs up!

Good sound
Solid construction
Five-year warranty

Blinking lights from signal LED are not on same horizontal plane (purely a cosmetic observation).
Module based, surface mount construction makes component level repairs difficult