Review: KV2 Audio SAC2 Controller

KV2 Audio is a small pro audio company based in the Czech Republic. Founder George Krampera has a long history of designing and building audio equipment including time designing for RCF. In 2001 he and a couple of colleagues from RCF joined forces and KV2 Audio was born. The company aims for the highest possible audio quality in its products, whether analogue, digital or hybrid, and they’re developed around George’s lifelong quest to “reduce distortion and retain the dynamic range and exact detail of the source sound”. That’s a beautiful philosophy if ever I heard one, and striving for this purity of sound has involved technical developments that have made KV2 both an analogue champion and a digital warrior.

Primarily speaker manufacturers, KV2 has begun branching out into speaker controllers, and I can see the logic in that. The SAC2 speaker controller is its latest product and although it’s been designed for use with KV2’s ESD speakers it can be used with any speaker system.

CROSSING OVER

The SAC2 is a cleverly designed processor that combines a two-way stereo crossover with EQ and dynamics to provide complete control of audio speaker systems. Most current system controllers are digital, whereas the SAC2 is a high-quality, latency-free, analogue design. It has outstanding technical specifications courtesy of KV2’s Super Analog technology that places great importance on the accuracy and speed of the underlying electronics. The result is a frequency response of –1dB from 3Hz to 40kHz, 115dB dynamic range and THD of 0.005%. It’s a 1U 19-inch rackmountable unit that’s pleasing to look at and a good example of how an analogue device can be simpler to use with all its functions on display and accessible via knobs or switches. A digital controller could have more functions but LCD displays and nudge buttons don’t compare to real controls for looks or ease of operation.

It’s a solid unit and at 3.2kg it feels like there’s a lot inside. The knobs, switches and meters are all good quality and well labelled. It looks simple and intuitive but the control options and operating modes are surprisingly comprehensive. Starting from the left there’s a section that contains a gain knob, limiter level knob and a 12dB/octave HPF that switches between 20Hz and 40Hz. The limiter has an active light beside the knob and on the rear panel there’s a switch that toggles both the limiter’s attack and release between fast and slow. The next section contains a four-band equaliser, with defeat switch, that cuts/boosts the signal at centre-points of 40Hz, 450Hz, 2.5kHz and 18kHz. Next to the EQ section there are dual notch filters for the left and right channels. These narrow-band filters are switchable between 6 and 12dB/octave and are intended to either tame PA/room resonances or reduce feedback hotspots. Combined with the four-band EQ section the SAC2 would provide sufficient EQ control for many systems, potentially eliminating the need for the traditional system graphic EQ.

DIRECT APPROACH

The output section to the right of the front panel has 4 x five-segment LED meters indicating the Hi/Lo output levels of the left and right channels. Knobs adjust the low and high output levels of both channels simultaneously. The crossover frequency can be switched between 70Hz and 120Hz and there are two switches that defeat the crossover filters and allow full-range signal to pass to both the low and high outputs. Although the SAC2 is designed mainly as a two-way crossover it could be used as a dual full-range system controller by switching both bands to Direct. For instance, the low output could be set to Direct and sent to FOH speakers while the high output could be set to Direct (or via the 70Hz/120Hz HPF) and sent to foldback or in-fill speakers. This setup would work well for bands that mix themselves from either on-stage or side-stage. The EQ and limiting would be across both systems but it’s an interesting idea and adds flexibility to its application options.

The rear panel has pairs of high and low XLR outputs each with a phase reverse switch. A Sub mode switches the low outputs between mono and stereo. Each output is driven by KV2’s VHD line driver technology that it claims is capable of driving long cable runs (over 100m) without signal degradation. The only other control is a switch to engage a low-frequency enhancement circuit that provides boost around 60Hz. This also works in full-range mode and adds another EQ option.

OUTDOORS, IN CONTROL

In use, the SAC2 is simple to connect and operate. I used it at an outdoor show with my trusty horn-loaded double three-way and noticed several improvements over my existing crossover setup but the main impression was that it just sounded better… clearer, punchier, very nice. The other improvements were the extra controls at hand. The sub EQ switch added some good solid low end and its set deep enough to get under the often overly-resonant 100Hz –160Hz region. The EQ section had enough controls to be able use it instead of my normal system EQ. Of course, because of my cabling the SAC2 was sitting near the stage with the amp racks and that made it impossible to adjust from the front-of -house mixing position, but once I was happy with the broad settings I found the channel EQ took care of individual tweaks to instruments or vocals. The four-band EQ has been designed to operate without interference between bands and with excellent phase response. It sounds super-clean with quite wide cut/boost shapes well-suited to overall sound sculpting while the additional notch filters were great for controlling the often unruly low/low-mids in my PA.

The limiter is designed to be as much a leveller as it is a system-protection device. Its attack and release times are quite slow and the control knob dials up the desired output level, rather than a threshold. It bites hard if it’s hit with a big level, as it should, but with music playing it’s commendably transparent even with a lot of levelling going on. Back home, I set the system up and did my best to do an A/B comparison to make sure I wasn’t fooling myself about the improved sound. I couldn’t switch from my usual crossover to the SAC2 instantly, or do a blind test, but the SAC2 always sounded better, which is great for KV2 but leaves me with the slightly uncomfortable feeling that my PA won’t sound as good next time I use it.

WITH KNOBS ON

These are hard units to fault but I had small concern with how hot it gets underneath the power supply end, almost too hot to touch. KV2’s technical people assure me that even if it does get too hot to touch it’s still within its normal operating range and it’s not going to overheat when mounted in a full rack of gear at an outdoor gig in the Australian summer sun.

And that’s it: simple but powerful, easy to understand and a pleasure to use. The KV2 SAC2 is not a cheap bit of gear but its top quality and very well made. I applaud the fact its analogue. Possible applications for the SAC2 include installations, clubs, churches, theatres as well as PA operators or bands that run their own gear. It would also be ideal for studio monitoring control. Great kit, well done KV2 Audio.