(click thumbnail)Fast FactsApplications: Live sound, installation
Key Features: Two-channel; 2,000 watts @ 2 ohms, 1,350 watts @ 4 ohms and 800 watts @ 8 ohms; anti-clip limiting processor
Contact: Crest Audio at 201-909-8700, www.crestaudio.com.I'm not sure how long you have been around the pro audio business, but odds are, if you've been in the business any length of time, you have used Crest power amps at some time in your career.
The 1980s saw the industry standard of power amps with models like the Crest Audio 8001, 9001 and the mighty 10001. They may well be setting a new standard with the new CC series.
The model we tested was the CC4000, so called 4000 because the amp is rated at 4,000 watts RMS in bridged mono mode at a 4 ohm load. But the other specs are equally impressive, with Crest rating this power amp at 2,000 watts @ 2 ohms, 1,350 watts @ 4 ohms and 800 watts @ 8 ohms, all ratings with both channels driven equally at 1 kHz.
Right out of the box, the CC4000 is a pretty good looking piece of gear, with a stout black steel case and a slick looking brushed silver control face with black expanded metal air intake. The control face contains two rotary input sensitivity dials, labeled Channel A and B (as opposed to L and R). Directly to the center of the two rotaries, are the LED input level stacks, displaying signal and amplifier status. The only additional item on the front panel is the Power On/Off rocker switch. And in the Crest tradition, it's a combination magnetic circuit breaker and On/Off switch.
The rear panel is equally efficient, with the IEC power connector residing alongside the output connectors. The outputs consist of a Neutrik NL4 and binding post (female banana) connector per channel, as well as a legend depicting the proper connector alignment for stereo and bridged use. At the other side of the rear panel, are the input connectors which are Neutrik combi 1/4-inch and XLR style connectors. This location also contains a three-position switch, allowing for input connector assignment to stereo (separate Channel A and B information), parallel (identical Channel A and B information), and bridged mono. If you have never done it, bridging mono is the somewhat unnatural act that combines the output of both channels into functioning as one power amp by using the positive swing of the wave in the Channel A amp and the negative swing of the wave in the Channel B amp. The output is then taken from the red banana output of one channel and the red banana output of the other channel. This particular Crest amp also assigns the bridged output to the Channel B Neutrik NL4 output connector.
I had this Crest CC4000 for only a short time, so I decided to give it a brutal two-day workout. First off, I wanted to hear the transparency and response speed (the response speed is commonly referred to as the slew rate, which essentially describes the rate at which an amplifier can process change in volume, and is measured in volts per microsecond). Although Crest rates this power amp very modestly at 15V per microsecond, it felt as though it responded much faster. The CC4000 was employed as a monitor amp, with Channel A in the lows character and Channel B in the highs character.
It acted out both parts with considerable aplomb and dexterity, responding to my old ears, with what I thought was much faster than rated by Crest. The vocal range was clean, concise and responsive, while the lower frequencies responded with equal speed and clarity. The CC4000 might be a little much for most monitor applications, but I felt that it would allow for the most critical listening environment in a loud, crowded casino showroom (Harrah's, to be specific).
We continued the show the second evening, which by the way, was a Doors tribute band called Peace Frog. The second night we decided to let it rip, and employed the CC4000 as a subwoofer amp. We connected the amp to a pair of A-Line Acoustics LS218 double 18-inch subs, and let the games begin. The CC4000 was even more at home as a sub amp, delivering incredibly smooth response at extended frequencies of 40 Hz with no difficulty at all. The kick drum had excellent attack response, and the bass keyboard (remember, it's The Doors!) had very rich extended synthesizer tones that purred at 40 Hz and 50 Hz.
The Crest CC4000 rocks with some of the best power amps in its class. It reminded me how Crest was once king of the touring sound hill back in the day. They keep doing this kind of stuff, they just may regain that title. Power amps come and go, but this one is a keeper.
Crest Audio CC4000 Power Amplifier Bench Test
(Unless otherwise specified, all tests reflect signals applied to the balanced inputs, both channels driving 8? loads, a measurement bandwidth of <10 Hz to 30 kHz, and the worst-case result.)
2 x 800 watts RMS into 8 ohms 1 kHz/0.05% THD; 2 x 1,350 @ 4 ohms, 2x 2,000 @ 2 ohms (0.1% THD), 1 x 4,000 @ 8 ohms (bridged, 0.1% THD)
Power at clipping (1% THD+N); watts, 2 channels driven at 1 kHz:
4 ohms, bridged >2500**
** See text; limited by AC available powerline voltage, and/or safe available dummy-load resistance
THD+Noise at rated power at 1 kHz:
8 ohms4 ohms
(1w, 8 ohms): +0, -0.6 dB <10 Hz-20 kHz
selectable; -25.3/-31.3 dBu for 1 watt into 8 ohms
17k kohms (both legs)
S/N (A-wtd./8?, 10 Hz-22kHz msrmt. banwidth, Gain switch set to "20"):
-84 dB re: 1w; -112.6 dB re: rated power (800 watts)
Damping Factor (re: 8 ohms):
30 Hz1 kHz20 kHz
This is an amplifier that make a lot of power; my bench tests were limited by sag in available powerline voltage — despite a 20 amp circuit, the heavy, supplied line-cord, and a 135-volt Variac — to the extent that 2 ohm and bridged-mode testing both reflect substantial reductions. Another handicap was my inability to jumper up more than 2 kilowatts worth of load resistance in 8 ohm or 4 ohm configurations, (and my reluctance to risk melting, at more than $50 a pop, any of the ten 250w 4 ohm and 8 ohm resistors I have…). Suffice to say that Crest's CC4000 met its specs, and then some, in every test I ran, falling short only where the above-named inadequacies limited performance. I did note that at low power levels the amp produces substantial mechanical buzzing (presumably from magnetostriction in its power transformer), and that at high powers on pure tones its switching circuitry (again, presumably), sings quite audibly. But where loudspeakers instead of dummy resistors are the loads, at these levels you are very unlikely to hear this, or much of anything else, other than the program! The amplifier got comfortably warm but never alarmingly hot, even on extended high-power runs; its dual fans seemed very effective, if hardly silent.
For the sake of clarity, all plots show one channel only; the two channels were effectively identical throughout.
Figure 1 shows frequency response into 8 ohms loads at, from top to bottom and offset to -1 and -3 dB for clarity, 1 watt, 100 watts, and 250 watts. The slight dip at 1 watt is well within Crest's specifications, and the increasing high-frequency rolloffs at higher power would seem exceedingly unlikely to have any audible impact.
Figure 2 graphs THD+noise versus frequency into 8 ohms at three power levels: 1 watt, and 250 and 600 watts, ranging from bottom to top along the 7 kHz log line. (Both channels were driven in all cases, but single channels shown for clarity.) Distortion at other power levels and with lower-impedance loads was along the same lines, never exceeding 0.5% even at high frequencies with 2-kilowatt, 2 ohm runs.
Figure 3 plots power against distortion into 8 ohm and 4 ohm loads (left and right, along the 1-watt line), in watts (horizontal) vs. THD+noise in percent (vertical). The 4 ohm test represents only 1 channel driven due to a shortage of suitable dummy-load resistors; the clipping point with both channels driving 8 ohms is short of the spec, likely not thru any fault of the amplifier, but due to inadequacies of powerline voltage, which sagged to about 110 volts at this point, despite a maxed-out 135-volt Variac in the circuit. A 40-amp 120Vac circuit, suitably wired, would be required to really get the full potential from this impressive power amp.