Furman Classic Series Power Conditioners

The Classic Series provides useful features and solid performance from a respected name in power conditioning gear.
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The Classic Series of 1U power conditioning units offers a wide variety of innovative features, providing nearly every audio professional a rackmount power solution to best suit individual, modern needs whether in the studio, at the show, or anywhere in between.

The Classic Series features three 15-amp (PL-8 C, PL-PLUS C, and PL-PLUS DMC) and two 20-amp (PL-PRO C and PL-PRO DMC) models, each of which was utilized within this review.

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Features

At the top of the feature list are Furman's own exclusive technologies — Series Multi-Stage Protection (SMP), Linear Filtering Technology (LiFT), and Extreme Voltage Shutdown (EVS) — together comprising the Series' Multi-Stage Protection Plus feature set, available in each Classic Series unit. SMP absorbs and dissipates surges and spikes, regularly handling 6000V and 3000 amp pulses, according to Furman specs. LiFT, an AC filter-conditioner, is designed to reduce noise without causing "resonant peaking," or noise added at specific frequencies (a problem found in traditional filter-conditioners, explains Furman documentation). EVS does just what it says: in extreme power environments, it cuts dangerous voltage levels (starting at approximately 15 percent above nominal) to all connected components. As voltage returns to normal, the EVS-equipped unit resets itself, and normal operation continues. [The manufacturer would like to clarify that its Classic Series products "do not regulate voltage; this is a common misconception with power conditioners," they note. — Ed.]

Each Classic Series unit offers nine grounded outlets: one on the front panel and eight on the rear; three of the rearpanel outlets are spaced for use with AC power transformers ("wall warts"). Other features include dual front-panel pullout lights with on/off and dimmer knob and rear-panel BNC lamp connectors. The PLPRO C and PL-PRO DMC also feature a handy front-panel USB charger.

From there, each Classic Series unit differentiates from each other only in amp rating and the manner in which it informs you of crucial diagnostic information: the PL-8 C simply features two LEDs in green ("protection OK") and a red ("extreme voltage"); PL-PLUS C and PL-PRO C feature a 20-LED horizontal voltmeter (90V to 128V); and PLPLUS DMC and PL-PRO DMC feature a voltmeter/ammeter via numerical LED display.

For all units, maximum surge current is 6,500 Amps, and spike clamping voltage is 188 VAC peak @ 3,000 Amps.

In Use

In addition to their obvious usefulness in studio, installed sound, and HOW/theater applications, all features of the Classic Series proved to be quite useful in the field — for example, the USB port on both 20-Amp models proves quite handy at festival-style live events. Need to charge an iPod or a cell phone, or keep your iPod charged while providing between-set audio? No problem. Another simply useful feature is the way Furman allows for "wall wart" space; for the 20-Amp models, Velcro straps and screws are included to secure wall-warts to the unit for better transport.

Once proven to be problem-free performers in the studio and/or in the shop, what does one test with a series of power conditioners? Live-sound engineer Karl Bader evaluated the series' performance in high- and low-voltage environments. "For those of us who do outdoor shows with generator power, irregular power can be a very likely situation," he insists. Bader used a Variac transformer inline with the Furman power input to simulate varying generator loads, monitoring the Furman's metering and indicators, and the brightness of a desk lamp plugged into the unit, to track the reaction to varied input voltage. On the high side, warning indications began as the input voltage reached 128 VAC, and the Extreme Voltage Shutdown protection shut down the output power as the input reached 140 VAC.

Summary

In conclusion, the Furman Classic Series features sleek and handy units that perform as pro users would expect. Once you choose your amp rating and desired method of diagnostic info display, you couldn't go wrong with one of these five Classic Series units.

Prices: $179 (PL-8 C), $229 (PL-PLUS C), $309 (PL-PLUS DMC), $359 (PL-PRO C), and $419 (PL-PRO DMC)
Contact: Furman Sound | 877-486-4738 | furmansound.com

Strother Bullins is the reviews and features editor for Pro Audio Review.