In conrad-johnson parlance, there is no such thing as an integrated amplifier. Of course, integrated amplifiers exist, but c-j doesn’t make them. Instead the company makes ‘control’ amplifiers. This is a power amplifier with basic source switching and volume adjustment of a solid-state line preamplifier in the same box. Just to make things even more confusing, many audio companies used to call a preamplifier the ‘control unit’ or even the ‘control amplifier’. The new CA150 integrated, er, control amplifier is the first such design from c-j since the CA200 of 10 years ago.
Delve deeper into the concept of the control amplifier, c-j style, and there is a distinction between a device like the CA150 and most integrated amplifiers. The company suggests most integrated amps throw the baby out with the bathwater, eliminating key features and better quality components just to make a cheaper product. Instead, the CA150 is more an exercise in high-performance space-saving, essentially combining the company’s solid-state stereo power amplifier with a solid-state variant of one of c-j’s preamplifiers in one chassis. In the process, rather than paring down the quality too far, the CA150 eliminates the need for potentially sonically deleterious long interconnect cables between preamp and power amplifier. Eliminating the line stage – especially a c-j tube line stage – also has a direct benefit in that the output at the loudspeaker terminals is in absolute phase (c-j preamps typically invert phase).
In fact, the amplifier is so ‘two amplifiers, alike in dignity’ that happen to share the same case, the pull to separate the sections in description is incredibly strong. Normally we’d describe this as a six/seven line input amplifier that is capable of delivering 135W into eight ohms, but that seems too reductionist. The six/seven input stage (six line inputs, plus one extra line input that is also a theatre by-pass input if required) bears a striking similarity to the ET3 preamp from the brand, with a Burr-Brown level control and the removal of the single 6922 tube for voltage gain (and unlike the ET3, there is also no provision for adding an optional phono stage). Instead, the CA150 uses the FET-based voltage gain stage of the power amplifier, which is coupled to a bi-polar output stage. As with all c-j designs, this is a low feedback design. Eagle-eyed c-j amp spotters may notice the FET-in/bi-polar out design is remarkably similar to that found in the company’s recent return to solid-state power amplification, the MF2550 and MF2775, and given the power output and size of the chassis, it’s fair to conclude this is basically most of an ET3 meets all of a MF2775 in one box.
The CA150 shares another key design element with the MF2775 power amplifier – it takes forever to come on song. We had this amp happily working away on a low gas for the longest time, and judging by the performance upgrades delivered by running in the power amp, there’s still a way to go. It’s already sounding pretty much great, though, but we know that a month longer down the line and this amp will continue to give up more. Deadlines trump extended burn‑in, however.