Amplifier 1000W
For over a decade, Chapter has sat at the forefront of class-D amplifier design. Technical director Duncan Shrimpton has worked on some of the world's most demanding solutions for consumer, industrial, military, aerospace and space environments. This extensive knowledge of high frequency, high power technologies has been applied to our 1000W analogue class-D amplifier design. Contrary to most class-D systems, our design is fully analogue in its nature. The control loop and feedback systems work in exactly the same way as Class-A, Class-AB or even valve amplifiers. The signal output from our amplifiers is an analogue signal.
To all but the most sensitive measuring equipment, and an expertise to know what to look for this is an analogue amplifier. But it does not suffer the drawbacks of a traditional analogue amplifier. There is no crossover distortion. There is no high gain feed-forward network to reduce the output stage distortion as used by so many class-AB designs, giving a sluggish "handbrake on" sound that always leaves you wanting more. The Output stage is ultra linear and requires only a 2nd order feedback network in order to achieve industry acclaimed performance figures. This means that RF corruption is virtually non-existent.
The results are simply stunning. Truly a world class reference design, doubling in power through 4-Ohms, this spectacular feat of high end engineering will take on the best that the rest of the world has to offer and win.
Amplifier 250W
This 250W analogue class-D power amplifier is a proven, robust and reliable foundation for our power amplifier designs. Featuring zero crossover distortion associated with Class-AB amplifier designs, this fully analogue system gives a flat "in-band" distortion response regardless of level. This means that all Chapter amplifiers will retain the exact same character at their highest level as they do at their lowest. Designed with RF interference in mind, any intermodulation distortion products are vanishingly low, this amplifier combines tight punchy Class-A style bass performance with a liquid Valve like mid-range and high frequency that is unrivalled.
Amplifier 125W
Featuring the same flat "in-band" distortion response and highly linearity output stage, this 125W design benefits from the most advanced MOSFET output stage devices available today. Using low-order analogue feedback control, this "mini-me" will drive the majority of high end speakers with consummate ease, whilst maintaining the character associated with our larger, high power designs.
Amplifier 50W
As with all of our amplifier designs, this "baby" analogue class-D design will punch far beyond its weight. Designed with the modern home in mind, this 50W amplifier is integrated into our most design conscious lifestyle products and will conduct even the most demanding bookshelf speakers as if a philharmonic orchestra.
Linear PSU 3000W
The bulk of the weight behind the Qube Reference products exists within this "Goliath" power supply unit. However unlike the biblical character, this power supply is no slouch. Featuring our unique transformer balancing circuit that allows Chapter to operate vastly higher magnetic power transfer ratios than would be normally allowed, the 3000W linear power supply remains perfectly poised at all times to meet the demands of the world's largest loudspeakers. Using custom magnetics providing a power transfer ratio well in excess of anything offered elsewhere, the Chapter 3000W linear power supply defies the expectations of size and efficiency and allows our largest amplifiers to give spectacular bass attack coupled with the ballerina finesse required in the mid-range to operate as true world class reference amplifiers.
Linear PSU 800W
The workhorse of our Hardback series power amplifiers, this 800W linear power supply features a unique transformer balancing circuit that allows Chapter to operate vastly higher magnetic power transfer ratios than would be normally allowed. This means that key factors that would normally inhibit the speed of a linear power supply to deliver bursts of energy are effectively negated. Our fully custom torroidal transformers are magnetically and electrostatically shielded and are will remain 100% silent in their operation both electrically and mechanically.
Linear PSU 300W
The 300W linear power supply like all Chapter linear power supplies features our unique transformer balancing circuit to ensure that the magnetic power transfer is always maintained free of harmful core saturation effects. Our secondary regulation features multiple Jung super-regulator technology stages with industry leading noise performance. A series of individually specified decoupling capacitors is included with each regulator chain to ensure that no effects of PCB layout are felt and that all designs are allowed to perform to their full potential.
SMPS 750W
The Chapter multi-phase "on-demand" power supply concept has been perfected through many years of research and development. Our technical director has worked with some of the leading power supply companies in the world and has made reference designs that are in use in some of the most well known household items. This sleek 750W, ultra efficient high frequency design regulates the power across the full audio bandwidth and is able to channel ultra-fast high power energy bursts directly to the required areas within the amplifier output stage. This dramatically increases the output stage linearity that is responsible for the utterly effortless and natural sound found in all Chapter power amplifiers as well as providing utterly jaw dropping bass attack.
SMPS 1200W
The flagship of Chapters' multi-phase "on-demand" power supplies. This 1200 unit uses both analogue and digital control loops to modulate three separate phases per power supply rail. The effect of this is to effectively share the output demand between three individual power supplies. This is analagous to the idea of a boxer fighting three individual fighters for 1 minute each rather than fighting one for 3 minutes. Obviously the demand on the three individual fighters would be much less.
This multiphase design gives and effective speed of power delivery of 3x that of a standard power supply design, meaning that we can effectively channel power directly to the areas that it is required with very little reservoir capacitance thus drastically reducing the effect of component selection in this critical area.
Apple MFI Program & Streaming
Advanced digital interfaces and streaming technologies are at the forefront of modern high end systems. Chapter has established partnerships with the technology providers for all of the leading streaming and Apple AirPlay technologies and will expand upon our USB based interface technology and will provide fully integrated wireless and wired streaming solutions throughout our product ranges during 2011. enabling seamless integration with any Computer as Source (CAS) system.
Vibration Control
Vibration can have a detrimental effect on the performance of individual components within any piece of electronics. This is especially true of Audio where structure borne bass energy (caused by loudspeakers, furnace rumble etc.) will influence every part of the audio chain from turntables to power amplifiers. In addition, transformers and motors found in audio equipment also generate vibrational energy that can affect the performance of other components within the audio chain. With this in mind Chapter approached vibration control experts, Audiophile Furniture Ltd with a view to incorporate their groundbreaking vibration control technology into its first product, the award winning Chapter Two power amplifier.
Working with John McCurly-Smith, the head of Audiophile Furniture Ltd, we were able to look at the impact of vibration on the Chapter Two, define which frequencies had the largest affect on the products performance and then target these frequencies for reduction.
Once in possession of all relevant data, prototypes of a unique beam assembly were made and the unit re-tested. The final design is very simple and robust. A metal beam spans between two support points and is isolated from the amplifier with a Sorbothane TM strip.
Sorbothane's unique liquid-solid properties allow it to absorb shock and isolate vibration even at high frequency ratios. Most other isolators are one-dimensional. They either isolate vibration or absorb shock. Natural rubber (as used in the manufacture of 'feet' for audio equipment) has a tendency to amplify at resonance 12 to 15 times the input force, making it totally unsuitable for supporting audio equipment.
By using Sorbothane in a 'spring-mass-damper' beam assembly we were able to isolate the amplifier from vibration while still protecting it from shock inputs. The effectiveness of our 'Spring Mass Damper' system is governed by the durometer or 'hardness' of Sorbothane used.
The siting of the beam assembly was also critical to performance of the vibration control system. In the Chapter Couplet, the beams are sited to maximise the units stability and to critically damp the base plate. Although the amplifier generates very little in the way of heat, the isolator material had to be able to withstand potentially high temperatures without deformation and degradation to its performance. Sorbothane maintains its performance from –30 degrees C to 90 degrees C.
In the Reference series, vibration energy is reduced by up to 90%, effectively isolating the amplifier from 5Hz upwards. The compliance of the beam, degree of damping and relative masses were fine tuned by ear and have given the Chapter One power amplifier even better subjective 'speed' and articulation at low frequencies, as well as a smoother more integrated high frequency presentation. Dynamic contrasts are now even more apparent with transients being faithfully reproduced.
The vibration control system used in the Chapter Couplet and upcoming CD players is protected under patent number GB2277789 for the UK, Europe and America. The concept has been licensed from Audiophile furniture Ltd, Europe's leading vibration control specialist.
Ultra Low Phase Noise Clock
One area of CD Player design that is poorly understood is the importance of the clock stability on audio performance. People usually discuss this in terms of jitter and attach a figure of picoseconds to a player in an attempt to quantify this. What is much more important however is the frequency domain cousin of jitter; Phase noise.
All oscillators will generate a noise level either side of their fundamental frequency. A typical high-specification TCXO or OCXO module will provide exceptional phase noise figures at a distance of >1kHz from the fundamental frequency. Usually in the region of -140dB or better. However, their performance at frequencies close to the fundamental is very poor. Typically in the region of -70dB @ 100Hz from the fundamental. This is great for telecommunications, (where adjacent communications channels are usually spread several MHz apart) but is awful for audio. This -70dB noise figure means that the analogue audio output signal will feature timing errors that are at best -70dB down at 100Hz.
The characteristics required for a good audio clock are very hard to find. Usually you will only see this level of specification in space oscillators for military satellite systems, and these cost in excess of £1000 each! Chapter have worked exclusively with leading clock experts to redesign a space oscillator for audio use. Stripping out the radiation protection reduces the cost to a commercial level, and allows the device to be operated in a more conventional oscillator oven package.
The Chapter oscillator provides a phase noise of -120dB at 10Hz, and -130dB at 100Hz. This allows all our source products to give a low frequency performance that is unsurpassed in digital audio.
RF Protection
All Hi-Fi systems are badly affected by RF Interference. At Chapter we noticed this problem many years ago when Wireless LAN systems were in their infancy. With a wireless LAN transmitter in the vicinity, the sound quality dipped vastly. The majority of airborne RF pickup takes place at the input stage of the equipment (which usually has a very high impedance) where it meets the incoming (audio carrying) cable. The majority of Hi-Fi equipment is the same, with the input signal meeting a MOSFET or transistor pair which (when slew limiting) does a great job of folding down any RF products into the audio band (This is the beating effect you get when you hold a Cell Phone near to a Hi-Fi system). In essence the from end of most amplifiers look very much like an AM radio receiver. To ensure that our products are tolerant to RF pick-up on the input cables all Chapter products either shield from or are not affected by high frequency input signals. The remainder of the signal path is protected from further airborne pickup by good layout and shielding as well as ensuring that signal pathway impedances are kept low enough to prevent pickup. Our Input stages use a JFET pair that do not exhibit the fold down effect.
That just leaves the issue of mains borne interference (RF or otherwise). This is where the Chapter products really come into their own; and it is no surprise to us that we won Best Power Amplifier Award in Hi-Fi News in 2005 as we are one of the only high end Hi-Fi companies whose products are designed to counter this problem. Our custom designed high frequency power supply uses an active Power Factor Correction boost regulator (PFC) to generate a "Clean" 385v DC rail prior to the step down process. This is a second order process that provides a roll off from just above DC at a rate of 12dB per octave and effectively removes any RF inference from the PSU right at the start. (NB. There are many PFC implementations out there, but only one designed for this function can provide it. The presence of PFC does not guarantee immunity to mains borne interference).
During the design process we decided to test our theories in Hong Kong, as it represents one of the harshest RF environments in the world. A testament to our success in this field is that we have won Best Product Awards for power amplifier and pre-amplifier alike in that market. The PFC design is an expensive addition to the power supply, but one which will prove its worth over the years to come. As time goes by, our competitors products will sound worse and worse as the level of background RF noise rises.
Our range of cables takes this process its natural limit by employing microwave shielding techniques to protect against RF pickup within the cables themselves, thus easing the burden on the amplifier section and allowing all products to perform to the designers specification.
Stream DAC
The Chapter Stream DAC stage boasts world leading dynamic range and THD+N performance. With dynamic ranges in generally excess of 130dB and THD+N performance at a stunningly low level of <-118dB (0.00018%), the Chapter Stream DAC represents the cutting edge of digital design.
Our custom filter design ensures that no alias products above -300dB are allowed through to the Stream DAC stage which provides unparalleled linearity and will enable even the most modest of source components to compete with the best high end alternatives.