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.
internal engineering is also impressive. As shown in the photograph on the
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).
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.
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
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
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.
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.
- Chris Groppi -