CosmeticsWith class D amplifiers becoming the standard for big power, the high output CE1000M class AB measures a bit on the large side at 17.5" x 11.25" x 2.6". Visually, the sizeable heatsink looks like a model Stealth Bomber elaborated upon by a tattoo artist. In the center of the amp is a chrome, epoxy sticker that displays the Cutting Edge tribal logo. The uniquely shaped heatsink fins were designed to allow multiple CE1000M amplifiers to be stacked. In this configuration they have a rather impressive look.
LayoutThe layout of this amp uses through-hole components. Internally, the CE1000M is clean; that is, the designers managed the circuit layout well without the use of messy jumper wires. There is a fan mounted in the PCB near the signal end of the amplifier. We could not figure out how it helps as there was no path for the air flow; it just blows through the board to the heatsink.
The class AB amplifier, which uses sixteen 130 watt Sanken bipolar power devices, employs 85 C capacitors that were used throughout, including critical power stages (see sidebar).
No inductors were included for the 12 volt power and, as the power supply is unregulated, no inductor was included there either. This amplifier uses no isolation between the power supply and the audio circuitry. Non-isolated amplifiers must use differential inputs to break the ground loop. This type of circuitry must have high common-mode rejection to reject supply switching noise and low frequency ripple that is generated by the power supply. We measured some distortion and noise introduced by this technique, especially into a 1-ohm load where the power supply current can exceed 120 amps (as seen in the power vs. distortion test). The graph "Distortion/Noise" shows this as well. Although this non-isolation/differential input technique increases distortion, it remained below 0.3% into 1 ohm, which should not be a problem when driving subs. This distortion level is lower than most class D amplifiers in this power class.
Audio input connections are standard RCA gold plated PCB mount connectors. There is also a buffered pair of line out RCA connectors allowing the amplifiers to be daisy-chained.
At the opposite end of the amplifier lie the power connections. These power and speaker connectors are made of heavy brass that is gold plated; an allen-keyed set screw to secures the wire tight. The hefty power connector can accommodate #4 gauge wire; the speaker connector can handle #8 gauge.
PreampThe crossover in the CE1000M is switchable on or off in low-pass mode only. This limits the user to select from either low-pass or full-range configurations. The slope of the crossover is rather steep at 24 dB/Octave, a slope that is not necessarily undesirable. The crossover frequency is variable from 30-250 Hz, leaving this amplifier only open for use in midbass and sub-bass regions.
On the low side of things is the subsonic filter. This 18 dB/octave highpass filter is variable from 25-70Hz and allows the user to turn it on or off. We are always happy to see subsonic filters on bass amplifiers; delivering power below the cutoff frequency of any ported enclosure wastes power and can be destructive to the speaker. This subsonic also goes high enough in frequency to make for a nice bandpass setup for a midbass speaker.
Cutting Edge also supplies a remote gain control with the CE1000M amplifier. This control detents the gain setting of the amplifier, allowing the user to adjust the amplifier output 0 to -26dB from a remote location.