- Written by Larry Hryshko
- Published on 06 August 2009
- Cambridge Audio 840 Series CD Player, Stereo Preamplifier, and Stereo Power Amplifier
- Page 2: Design Features of the Cambridge Audio 840 Series
- Page 3: Set up of the Cambridge Audio 840 Series
- Page 4: Cambridge Audio 840 Series in Use
- Page 5: Conclusions About the Cambridge Audio 840 Series
- All Pages
840C CD Player
Normally, I'm far more interested in how a component sounds rather than how it was designed, built, and marketed. However, in this case, Cambridge Audio certainly didn't leave me with a lack of things to write about. The 840C is truly a technological marvel, offering up a smorgasbord of interesting and desirable features. It's hard to know where to start, but let's try near the beginning. CD data at 16 bit/44.1 kHz is upsampled to 24 bit/384 kHz using an Adaptive Time Filtering (ATFTM) process developed by Anagram Technologies of Switzerland. This process utilizes an advanced interpolation algorithm to generate the additional information between the CD's data points, providing a number of audible advantages including a pronounced reduction in jitter and error harmonics. Each channel then has its own 24 bit DAC (Analog Devices AD1955) which is subsequently processed by individual, symmetrical analog filter circuitry. Nyquist theory be damned, upscaling CD data truly offers significant audible benefits.
The 840C not only improves upon the sound of Redbook CDs but you can also utilize the sophisticated DAC circuitry and upscaling capabilities for two additional digital inputs. Digital sources can be input through either a Toslink optical connector or a S/P DIF coaxial cable. These additional digital inputs are accepted in a variety of word widths and sampling frequencies, and can either be passed through directly or processed to several other word widths and frequencies. Overall, the 840C offers a great way to improve the quality of your CDs and other digital sources such as DVD, media servers or IPod docks. While I reviewed the entire 840 system as a stand-alone unit, it is designed for easy integration into more complex environment through the use of its RS232 port, a Control Bus input/output and an infrared emitter input. I can't think of any other CD player offering more bang for the buck than the 840C.
Appearance wise, the 840C is pretty much, just straight business. The thick aluminum face has a minimal number of buttons for essential CD functions with two additional buttons to access and select from the numerous menu options. A large LCD panel and the well constructed CD tray occupy the center of the unit. The LCD provides information on track number, upsampling rate, and elapsed or remaining time. LCD backlighting can be toggled between bright, dim, and off either from the front panel or the remote. The menu and select buttons allow you to toggle between the two digital inputs or CD playback. All functions are also controlled by the well designed and hefty remote, which has the additional large benefit of providing amplifier and pre-amplifier control. I found that the remote from either the CD player or the pre-amp accomplished everything one needed for ordinary listening. Nice, nice, nice.
The 840E is Cambridge's top of the line stereo pre-amplifier. It accepts a total of seven inputs, including two balanced inputs using XLR connections. Like the 840C, it has a number of features that allow for easy integration into a multi-room system such as a Control BUS Input/Output, RS232 control, an IR emitter input, and trigger input/output and throughput connections. The 840E is physically designed similar to the CD player, with a larger central LCD panel indicating the volume level and the input being utilized. The display can be switched to scroll through other functions such as balance, treble and bass, or direct throughput bypassing the tone controls. All inputs can be named, as desired, and a number of other nice features include the ability to trim the various input levels of different sources to yield common levels of loudness when switching, switching the volume ramping function on and off at start-up/shutdown, and a headphone output. The 840E can also be directly synched to a matching 840W power amp, a feature which I utilized and loved. For those employing smaller monitor speakers, there is also a sub output which can be run full range or low-passed at 200 Hz. Both balanced and unbalanced outputs are available at rear.
The heart of the 840E's audio quality resides in its design, superb build quality and the utilization of a number of novel technologies. Proprietary Terrapin (10 pin) amplification modules designed by Cambridge are utilized rather than pedestrian op-amps for the low level gain stages. Precision resistor ladders are utilized for volume and balance controls, rather than common potentiometers. There is definitely an authoritative feel to volume changes with a pleasing click between each transition as the gold plated relays conduct their business. Physically, the case is rigidly designed and acoustically damped within, sharing the same thick faceplate with other "8" series components. Yet none of this would matter if it didn't sound great………..but it does.
840W Power Amplifier
Cambridge designed a new amplification topology for the 840W, referred to as Class XDTM. Essentially this functions to move the zero crossing transition point of conventional AB designs to a different level, boosting the range of pure class A operation. Once this is exceeded, the amplifier then switches to an improved class B design. A white paper provided on Cambridge Audio's website is very informative regarding the goals and improvements associated with this topology. Again, build quality is evident throughout from the acoustically dampened, rigid chassis and their choice of 1% tolerance metal-film resistors, gold plated bus bars and polypropylene signal caps. Similar to the other "8" series components, there is outstanding flexibility with the 840W. This includes a duplication of all the control features (control bus, trigger functions, IR emitter in) available on the 840E and 840C but more impressively, one can run this amplifier in conventional stereo mode, bi-wired stereo mode, bridged mono, and bi-amp mono (provided one is fortunate enough to have two 840Ws).
Overall, it is clear that Cambridge Audio focused on providing an acoustic blitz rather than aesthetic glitz with all components in the Azur "8" series range. With this mission accomplished, their efforts were then placed on providing tremendous flexibility, convenience, and ready integration into multi-room systems. Visually, the components speak quality but are unlikely to garner any oohs and aahs until they are turned on.