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Review: Lab.Gruppen FP+

The follow-up to Lab’s respected FP series needed to be something extraordinary…

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10 February 2007

Review: Ben Burns

The first thing that occurred to me when I held this amp, was how light it was. In fact, my elderly neighbour took the delivery for me with no problem. The second thing was how clearly evident the quality of build and design was, filling you with quiet confidence. The third thing was the amount of amp per square inch on offer here. There are four models in the new FP+ series – two are four-channel devices, the others a more conventional two-channel variety. All models come with a six-year warranty.

The idea behind the FP+ design is to provide a series of high-quality amplifiers that can drive virtually any load in the world. Because the SNR (Signal to Noise Ratio) is high (112dBA) and the power handling so great (up to 10kW), these amps would instantaneously fry a small speaker were it not for some innovative power controls. Each of the amp’s channels feature three DIP switches, which configure a voltage-peak limiting system (VPL) that automatically optimises each channel for maximum headroom. There are also three DIP switches to set the input sensitivity (in eight steps from 23dB to 44dB). Used together correctly, these switches set the amp to work as efficiently as possible, bringing it closer to its optimal SNR performance.

The new technology behind these marvels includes a very light, regulated switch-mode power supply. Optimised by active monitoring, the power supply is designed to remain stable even when the supplied voltage drops by 20 percent. Thanks to a soft start-up mode, this amp draws five amps when you turn it on.

Another key feature is the development of the Class TD amp stage, a mixture of analogue audio with digital control. Here’s what Lab has to say about TD: “Class TD is bridgeable, highly reliable, and maintains a flat response with complex loads as low as 2Ω nominal. Also, it does not interfere with RF equipment such as wireless (radio) microphones.”

As I mentioned earlier, there’s an enormous amount of power on offer, but the FP+ amps run remarkably cool. If you take a peek through the back grille you’ll be able to see the secret to the cool running – a large area of tiny copper ‘pipes’ that act as a new-generation of heat sink. Named ‘Intercooler’, this Mad Max-esque system of copper mayhem works great so long as the exhaust area at the rear of the amp remains clear – no space is required between adjacent amps. There are also two multi-speed fans drawing air into the front panel via two easily-cleaned dust filters.

As you’d imagine, there’s an advanced protection/warning suite that includes protection from DC at output, short circuit, excessive output current, sustained very high frequency (VHF), and open load. The VPL circuit also guards against accidental power cuts, by monitoring the incoming mains current. If the current drops too much, VPL will limit the current draw to prevent power interruption. Another protection circuit (CPL) looks after voltage, current, and temperature control. In extreme conditions (lo-Z, hi-Z, temp limit) the amp can mute as it reassesses the situation, checking every six seconds if the problem is still there. Advanced power management is a big player in the success of this amp. The inrush current draw when switched on is low and gradually climbs, preventing problems with mains supplies. This also allows several amps to power up at the same time without throwing a fast reacting trip switch. It’s because of these advanced features, I presume, that there’s no switch to select different operating voltages.

If you need to look at computers instead of the amps you can get the optional 1U ‘NLB 60E bridge’ allowing network control of power, mute, solo, and monitoring of status. The network is made with standard Cat-5e cable ideally as a loop, and then the amps address themselves. Using standard TCP/IP protocol and phantom powering, the NomadLink network can see devices whether or not they have power. If any problems arise, an alert is flashed down the network and you get an alert on the proprietary DeviceControl software.

FROM LAB TO ROAD

The first task I was able to give the amp was running monitors for a function band – menial duties for a powerhouse, but duties nonetheless. After a brief (but essential) encounter with Ohms Law I figured my monitors required a voltage limit of around 50V. Setting the VPL system in conjunction with the input sensitivity produces a limited voltage output suitable for almost any speaker/input combination.

Based on the trusted FP Series of touring-designed amps, the FP+ amps are intended to produce the same sonic signature. In my initial hitout that was somewhat difficult to gauge, but it was very loud. The clarity was compromised by the performance of the monitor speakers – passive cheapness. Next, when used to power half a small line array, the flexibility of these products became obvious – plenty of power with warm sub, tight mids, and crystal-clear high-end without sounding too digital.

Whether you invest in one of these amps or a hundred you won’t be disappointed. They’re a premium product selling for a premium price, but the innovation, the power handling, the build quality, and the sound all clearly indicate solid value for money. And, finally, what truly sets these amps apart, is the flexibility. Being able to dovetail your input and output requirements to that of the amp means you’ll be turning to the FP+ time after time – whatever collection of cabinets you happen to have this amp can do it, no question.

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