Electro-Voice CPS-3
A 1,200-watt-per-channel workhorse that was never meant for your living room.
Overview
The CPS-3 is the third rung of Electro-Voice's CPS Series of power amplifiers. EV aimed the line at fixed installations: clubs, houses of worship, stadiums, rooms where the amp lives in a rack and nobody ever touches it. The spec that matters most is the one printed under "Maximum Power": 1,200 watts into 2 ohms, 900 into 4, and 560 into 8, both channels driven at 1 kHz with less than 1% THD. On paper it sits between the CPS-2 and the CPS-4. The CPS-2 manages 850/600/380, and the CPS-4 jumps to 1,800/1,300/850. The CPS-3 is the middle child. It makes the most sense for a lot of permanent installs where a CPS-4 is overkill and a CPS-2 leaves headroom on the table.
Rated power tells a more honest story. At under 0.2% THD across 20 Hz to 20,000 Hz, full bandwidth with both channels driven, the CPS-3 is good for 1,000 watts at 2 ohms, 800 at 4, and 500 at 8. That's a real step down from the 1 kHz numbers, and it's the figure to quote when someone asks what the amp will do with program material. Bridged, it's rated for 2,400 watts into 4 ohms and 1,800 into 8, both at 1 kHz and under 1% THD. For subwoofer duty or a single-cabinet PA run, the bridged mode is where the CPS-3 earns its rack space.
The CPS Series has Electro-Voice's "Nonlinear Signal Monitor," a dynamic limiter the company claimed holds distortion under 1% even when the amp is pushed into clipping. EV's own literature said this eliminates the "hard-edged" clipping that kills speaker drivers. It's paired with a power supply designed for burst output exceeding 130% of the amp's average continuous rating. Whether or not you buy the marketing, the design intent is clear: an amp built to survive abuse in a room where nobody's watching the clip LEDs.
Slew rate on the CPS-3 is 35 V/µs, between the CPS-2's 30 and the CPS-4's 40. Total harmonic distortion is spec'd at under 0.05%, and intermodulation distortion at under 0.01%. The CPS-3 and CPS-4 both use the tighter 0.01% IM figure, while the CPS-1 and CPS-2 are listed at 0.08%. Crosstalk at 1 kHz is stated as greater than 70 dB, which is looser than the 80 dB the CPS-1, CPS-2, and CPS-4 carry. Whether that's a measurement artifact or a real difference in layout is hard to say from the spec sheet alone. It's the one number where the CPS-3 sits below its siblings rather than between them. Input impedance is 20 k ohms balanced.
The protection system is where EV put real engineering effort, and it's the feature the company led with in its sales copy. There are five separate circuits: over-temperature protection, DC protection against direct shorts, an excessive back-EMF monitor that guards against reverse current from a failed speaker, a low AC line voltage monitor to handle brownouts without damage, and a four-stage front-to-rear cooling fan system. The CPS-3 and CPS-4 get the four-stage fan arrangement. The CPS-1 and CPS-2 make do with three stages. Electro-Voice's line-radiator columns of the early 1960s were advertised as the first to provide truly uniform level throughout 160°, part of the company's push to bring line-source advantages to all frequencies (Audio, October 1961, p.49). Power requirements are 120 V at 50-60 Hz, factory configured. The amp carries a three-year warranty, which for a fixed-install product of this class showed how confident EV was in the design.
The CPS-3 is not a hi-fi amp, not a studio reference amp, and not a piece of gear anyone bought for its sound. It's a tool. The CPS Series was designed for sound contractors, and the feature list reads that way: protection circuits, thermal management, brownout tolerance, bridged output for subs. Anyone looking at one today is probably restoring a permanent install, building a budget PA or subwoofer rig, or is excited by 1,200 watts at 2 ohms for reasonable money.
Collectors and install techs who've worked with the CPS Series tend to praise the reliability and the protection system, and to note that the amps are heavy and utterly unglamorous. Parts availability for a 2000-era Telex-era Electro-Voice amplifier is what it is. The company was folded into Telex Communications by the time these were shipping, and service documentation exists but isn't thick on the ground. The 3-year warranty is long expired on every unit out there. Plan to recap it, check the fans, and verify the protection circuits actually trip before trusting it with a set of drivers you care about.
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