Classe Cap 2100 Integrated Amp Boxed
Integrated amplifiers have often been considered a compromise when compared to a separate preamplifier and amplifier, but in my opinion they have always offered the best combination of performance and value for all but the most expensive systems.
One of the most expensive parts of an electronic component is typically the chassis. With an integrated you only need to pay for one, which can save a huge amount of money given the same level of electronics inside. Also, integrated amplifiers need no line level interconnects between the preamplifier and power amplifiers, which improves performance as well as reduces cost.
So why aren't integrated amplifiers more popular in high-end audio circles? There are several reasons, some real and others perceived. Some believe that the separate chassis offer better performance, separating the higher voltage amplifier stage from the lower voltage preamplifier stage.
While simple distance can reduce any problematic interference, so can careful engineering in a well-designed integrated amplifier. However, an integrated amplifier prevents you from upgrading either the preamp or the amplifier; you must upgrade both, or use the pre-outs if they are present.
I manage to keep components for many years in my system. If you just have to change components of your system on month-timescales, maybe an integrated amp is not for you. But if you like to listen to your system, and get the most performance for the dollar, maybe an integrated amplifier is the answer.
Another real problem is that, until recently, high-performance integrateds have been difficult to find. Many manufacturers have only made "value" integrated amps, or have not built them at all. But products like my Plinius 8150i, their latest 9200i, the Jeff Rowland Concentra II, the Krell KAV-400i, and several others, have changed the integrated amplifier playing field.
The CAP-2100
Classé has always offered several integrated amplifier models. My first "real" high-end system had a Classé CAP-100 at it’s heart. This amplifier was a fantastic value, combining high build quality, with great sound and features at an affordable price. Eventually the upgrade bug got me, and I moved to a Plinius 8150i, which I still have. Since the CAP-100, Classé has offered many integrated products, with ever improving sound quality and features.
Classé became associated with Bowers and Wilkins (B&W) in 2001, and Classé now has the engineering and financial might of a major electronics manufacturer behind them. Classé is now the flagship high-end electronics manufacturer in the B&W group. This has fueled the development of their super-high-end Omega product line, and the Delta series, of which the CAP-2100 is the integrated amplifier offering.
The Delta series products include many of the lessons learned with the Omega series. The Delta series is a bit of a departure for Classé from earlier product lines. Design has become a more important component of the products, and build quality, features, and level of performance have all taken a considerable step forward. And of course, like all products, the prices have also stepped forward.
The CAP-2100 is a single chassis version of the CP-500 preamplifier and the 100W per channel CA-2100 amplifier. It shares the Delta series cosmetics of the other products, with a deeply rounded extruded aluminum front panel, and a prominent blue backlit touch-screen for control.
Volume control is provided by a large knob which drives an optical encoder. All user input is processed via a microcontroller, as in many modern electronic components. The microcontroller is firmware upgradeable with a RS-232 port on the rear panel. The CAP-2100 offers three single-ended inputs (RCA jacks), and one balanced XLR input. A tape loop is provided, and one of the inputs can be converted to a unity-gain SSP pass-through simply by choosing “SSP” as the name of the input. Four pairs of high quality five-way binding posts allow for bi-wiring. The touch-screen interface allows customization of input names, volume knob sensitivity, acceleration and maximum level, and balance, among many others. An optional MM/MC phono stage is available, although the review sample did not include this feature.
Product Review
Classé CAP-2100 Stereo Integrated Amplifier
Part II
October, 2005
Chris Groppi
Build Quality
The quality of the CAP-2100 is absolutely superb, both inside and out. As electrical engineering is an everyday part of my work, I regularly compare the build quality of high-end audio components to the Agilent/Hewlett-Packard microwave test equipment I use in my work. The hope is that the internal build quality and engineering that I see in our $75,000 Agilent PNA Vector Network Analyzer is repeated inside a high-end audio component, even if the audio component need only operate to 100 kHz rather than 20 GHz.
The chassis of the CAP-2100 is very attractive and massively over-engineered. Most high-end audio chassis are far more elaborate than professional test equipment costing ten times more. The CAP-2100 chassis is built around a massive front panel extrusion more than 5mm thick, mated to equally serious extruded aluminum heat sinks, and a main chassis frame made from aluminum extrusions and machined components all securely bolted together. A huge machined cross-member stiffens the chassis. There is no sheet metal in the CAP-2100. Even the top panel is an aluminum panel 1/8” thick, with vibration damping on the inside face, secured with no less than 12 countersunk hex head bolts.
The internal engineering is also impressive. As shown in the photograph on the right, a circuit board at the rear of the unit contains the preamplifier circuitry. This board is physically separated from the other boards. RCA and XLR inputs are directly mounted to the board, and switching is provided by high quality digitally controlled relays.
The preamp circuit is based on the Texas Instruments OPA-2134 audio op-amp, and the PGA-2310 digital audio volume control (a single IC containing op-amps and digital potentiometers).
The preamp circuit is fully differential to take advantage of the balanced input. A mix of surface mount and traditional through-hole components are used where justified. The circuit boards themselves are low dielectric FR-4 multilayer boards with especially thick plating. Traces are wide and have radiused corners. The low dielectric constant of the board minimizes crosstalk and potential phase errors due to unequal length signal paths. All unused board real-estate is covered with a ground layer, minimizing the infiltration of noise.
Amplifier transistors are heat sunk directly to the extruded heat sinks, with amplifier circuit boards mounted above. As usual with Classé designs, a combination of MOSFET, J-FET and bipolar transistors are used for the best performance.
The two amplifier channels share a minimum of circuitry. The center of the amp contains the massive, custom-made toroidal transformer and power supply circuit boards. A control board with voltage regulation and a PIC microcontroller sits above the main power supply board behind the transformer. The digital control board containing an ARM microcontroller (really a tiny CPU as used in PDAs) is mounted directly behind the front panel, and communicates with the LCD touch-screen and the optical volume encoder. Control signals are conveyed from one board to the next with ribbon cables, while power is supplied with discrete wires and Molex-style connectors.
The preamp and amp boards are connected with shielded, balanced cable of suitable audiophile quality. The amplifier stages are connected to the binding posts by gold-plated solid copper bus-bars that can only be described as incredible. One of these is pointed out by the white arrow in the photo above. I’ve poked around my share of high end audio equipment and lots of high-dollar test equipment. Short of the glory days of Hewlett-Packard microwave test equipment built in the early ‘80s, this is one of the finest examples of electromechanical engineering I have ever seen.
I have only three reservations about the design of the CAP-2100, relating to the choice of a microcontroller based interface. It is my gut-feeling that if a more traditional interface were chosen, the CAP-2100’s $4,900 price tag would be lower. While this is a fantastic product, the price will push it out of the reach of most audiophiles. A quaint set of mechanical knobs could have been substituted for the fancy interface, possibly cutting the cost.
According to Classé, a more traditional interface could reduce the cost, but only by a small amount. By using the same interface system for all of their Delta series components, development costs are spread out. Another annoying offshoot of the Classé interface implementation is that the CAP-2100 loses all custom settings when the power is interrupted, even for a split second. I had to rename my inputs several times when the Arizona monsoon season's lightning forced me to unplug my system. Classé told me this should not be so. After putting the unit into standby once, the settings should be saved, so my unit's firmware could have a small problem. The third reservation concerns reliability. The first CAP-2100 I received had a non-functional volume knob. Any electronic component can have a problem, and this failure was likely not the fault of a design issue. Classé says they actually have fewer problems with the optical encoder setup than they did with earlier, mechanical potentiometer designs.
The Sound
After installing the CAP-2100 in my system and allowing a couple of weeks of everyday TV-watching for break-in, the Classé did not disappoint me. The CAP-2100 was the first component to live in my system that completely transformed every area of performance. It dramatically improved shortcomings I thought were the fault of other components, and improved others I didn’t even think needed improvement. The change was so overwhelming and complete, it was like I had a whole new system, with every area of performance improved.
The first thing I noticed (or more precisely felt) was the bass extension, impact, and weight. I have a REL Strata II subwoofer, so you might think that there’s no way the amplifier could change the low bass performance. I didn’t think so either, but I was wrong. The transformation was spectacular. The bass with the Plinius 8150i was plenty good before. But the bass with the CAP-2100 was in another league. The extension seemed to go another half octave deeper. The power and weight were stunning. The bass didn’t just seem to fill the room, it felt like it was coming directly from inside me, like my heart was replaced with the subwoofer driver. Bass transients and timbre were in another league. And I thought I had no issues with the bass performance of my previous system.
The REL uses the high level speaker outputs of the amp as the input signal (with very high input impedance, so there’s no current siphoned off, and no load to interfere with driving the satellite speakers). This preserves the character of the amplifier stage as well as the preamp, improving sub-speaker integration. Somewhere in the CAP-2100, either in the preamp, the amp or both, there is some serious bass mojo. It’s clear the bass performance is still there when driving speakers. With the REL turned off, the lowest octave was missing, but the weight, impact and tightness of the remaining bass was still there. It has always been said that the Platinum Audio Solos have great bass for a little speaker, but this amplifier really brought out the best I have heard from them. And all this with “only” 100 watts per channel. The Plinius has 50% more rated power, but the Classé paddled its backside in the bass department. I’d like to know at what impedance the CAP-2100 starts to deviate from behaving as a perfect current source. I bet it’s a low number.
The bass was the most obvious area of improvement, but not the only area. Another striking change was the magical appearance of soundstage depth in my system. I always thought it was a shortcoming of the Platinum Audio Solos that they just didn’t have much soundstage depth. Wrong again. I started with a relatively flat soundstage with hints of depth, and plenty of width and height. This was pretty good. The CAP-2100 preserved the width and height, but added at least two meters of depth with well done recordings. I finally was able to get a soundstage that stretched from just in front of the speaker plane, back though the wall of my house practically into my neighbor’s yard. I just sat there listening with my eyes closed and a silly grin on my face.
A third area of my system I had blamed on my Solos was resolution of detail. I believed I just needed better speakers to squeeze that last little bit of detail out. I was always aware that there was just a little veil of obscuration between my ears and the sound, like having pretty clean glasses, but not brand new glasses right out of an ultrasonic cleaner. Maybe I still need better speakers and source electronics, but the CAP-2100 brought out more detail and precision than I thought was possible, given my system. With the Plinius, I had plenty of detail recovery above about 1 kHz, but in the midrange and bass, the sound could get a bit muddled during complex passages. The Classé cured this issue, leaving nothing but sparkling clear, detail-rich sound at all frequencies.
The combination of the detail resolution and the bass performance led to an amp that sounded incredibly alive and exciting. And what was so impressive was that the Classé had replaced a vary fine amp. In fact, having gone back to the Plinius toward the end of the review period, I was still impressed with the performance of the 8150i. The Classé is just better, in every way.
The only possible problem is that the CAP-2100 did not sound as warm and rich as the Plinius. This is likely a reduction in low order harmonic distortion, a price that is required to improve extraction of detail. I think this is a small price to pay. The CAP-2100 is the best component I have ever had in my system.
Conclusions
I would have no reservation recommending the CAP-2100 to anyone who wants a no-compromise integrated amplifier. Affordability is the only issue, but if you want the best, it is an issue you just have to work out. Since I want to say, "I bought the review sample," it is an issue I am working on as you read this review.
