Review-published June 2002
EYEFI magazine, Norway
The Chapter Two switched mode power amplifier
Once in a while there appears on the audio firmament a component that is destined to become a classic from the moment it is launched. Chapter Audio in England happens to have created such a benchmark product.
As a music lover and audio critic I have been listening to hi-fi equipment for the past forty years and my own personal listening has been via valve equipment for more than twenty five years. For those of us who use live music as the only valid criterion on which to base the evaluation of recorded music - analog or digital - good valve amplifiers are generally felt to deliver the most believeable and enjoyable reproduction of the sound created by musical instruments. Even though many successful modern solid-state designs, such as Mark Levinson, Krell, Classé, Rowland Research, Goldmund etc, have impressed me with the sheer power and solidity of their performance, I have so far always preferred to return to the more relaxing naturalness of my own valve amplifiers. A properly implemented valve design has the ability to render the richness and complexity of instrumental timbre, so that a recorded and amplified human voice sounds more truly "human" and instruments simply sound more convincingly like themselves. Among the many other virtues of valves is their superior ability, in my opinion, to replicate with greater accuracy the three dimensions of sonic images resonating in a three-dimensional acoustic space. Too many solid-state designs are less holographic than valves because they often tend to flatten instruments and voices, even if modern transistorised amplification successfully recreates the depth of the recorded soundstage. Valves are also particularly successful in rendering the most subtle microdynamic gradations of a recording as well as other low level sonic cues within the recording venue. It is such essential details which contribute to the credibility of the musical illusion which we are trying to experience through the playback of our analog or digital sources.
It cannot be denied, however, that the most sophisticated solid state circuitry today is in many ways approaching the ability of valves to render both instrumental timbre and the three-dimensionality of sonic images. The gap between transistors and valves is closing fast. But it also has to be said that valve designs also have improved substantially over the past decade so that we have a situation now at the beginning of the millennium where there is healthy competition between both approaches to amplification. However, valves have a few undeniable generic weaknesses: they are inefficient, run hot, they often have a short life and vary in reliability. They are usually noisier than modern solid state devices and high output valve power amps are also prohibitively expensive.
The best of both worlds
Congratulations to Chapter Audio for having implemented and brought tomarket a real-world power amp that combines the most desirable virtues of both solid state and valve amplifiers. I have been able to listen to the incredible Chapter Two switched mode power amplifier at regular intervals for the past six months. Together with an experienced team of music lovers I have had the pleasure of evaluating the quite extraordinary performance of the Chapter Two in four carefully calibrated high-end systems using every conceivable kind of programme material from Presley to Purcell, from Hodges to Horowitz, from Madonna to Mahler. To put it simply: this amp is equally at home with everything you might care to throw at it. It doesn't have any identifiable signature, it doesn't sound like valves and it doesn't sound like transistors. It simply sounds like "music". And not only does it reproduce all types of music equally well, it will drive any kind of speaker type (and load) imaginable, from high-sensitivity horn systems to the most insensitive speakers. My favourite speaker is the beautifully crafted Sonus Faber Amati from Italy. It sounds more like a musical instrument than an electromechanical transducer. More than any other speaker used during the test it was capable of showing what an amazingly subtle and nuanced amplifier we were listening to. With a rated output of 200W into 8 ohms, or 400W into 4 ohms, and with its ultra-fast switched mode power supply - it recharges itself 1000 faster (!!) than any conventional amp - it drove the Amatis with such effortless ease that I could have sworn we were listening to a cross between a supercharged single-ended triode amp and a pair of hideously expensive Krell monoblocks. On the same speakers, and using the Conrad Johnson Premier 16LS linestage, we were able to carry out an A/B comparison test between the Chapter Two and the far more costly Sonic Frontiers Power 3 Special Edition monoblocks powered by a grand total of (very hot) 16 KT88s. Both power amps delivered a palpable and utterly natural midrange, but the Chapter Two had a slightly tauter and more extended bass. Both had a sweet treble, but I preferred an even purer and airier treble that seemed to extend for ever when we used Chapter Two.
The Chapter Two also showed its paces in another system consisting of a Hovland HP1 preamp and the JM Labs Mezzo Utopia speakers that, despite their fairly high sensitivity, are a little hard to drive and can tend to sound just a little sluggish in the bass. Again, the Chapter Two performed with conspicuous ease and the Mezzo Utopias took on an irresistibly rhythmic drive and an unexpected light-footedness that was not in evidence with either the Chord FPM 1200C or a Conrad Johnson 2300, both solid state designs used for comparison purposes.
What finally won me over completely was the way Chapter Two convincingly and unexpectedly outperformed my own reference amp, the Italian GRAAF GM 100, an elegant OTL design that has so far remained my personal favourite. Alas, the Chapter was to change all that! My custom-made speakers, using ESS 12" bass and 8" midrange drivers supplemented by the Heil EMIT tweeters, are mercilessly revealing of everything fed into them. The one CD that really illustrated the shockingly superior transparency of the Chapter Two was an old recording, transferred from LP to CD, by the distinguished pianist Rosalyn Tureck. This CD reissue of her complete set of the Bach Partitas (Polygram 456 976-2) was originally made for EMI in the late 1950s. Hers is an outstanding performance, but the CD has always sounded somewhat veiled and with a bit of noise, inevitable in such an old recording. The Chapter Two, with its startling clarity actually managed to lift several veils away from the recording and with its greater incisiveness and transient attack, it brought Rosalyn Tureck's Steinway out of the sonic murk of the old recording and brought it to startling life. I can only attribute this audible improvement to the outstanding clarity, speed and energy of the English amp which imbued Miss Tureck's performance with the life and presence that it must have had originally, but which my slower and noisier valve amp had been incapable of reproducing.
A farewell to valves
The Chapter Two has revolutionised my attitude to solid state amplification. It is completely free from such traditional solid state artefacts as grit, grain and glare. Its absence of perceptible noise in any part of the audible frequency range - no mains hum or treble hiss - and its startling clarity and lucidity and its wonderfully relaxed, effortless reproduction of dynamic peaks and massive crescendos, are qualities that make this the easiest amplifier I have ever listened to in my own, or any other system. In addition to this, it possesses in full measure the natural warmth, rich timbral balance and holographic rendering of instruments and voices so that you sometimes feel you can somehow "see" around them. The rendering of razor sharp transients and almost inaudible low level information, obscured beneath the noise floor of lesser amplifiers, are other virtues of the Chapter circuitry and power supply that you immediately notice on first hearing this amp. In other words, there is much less that gets between the listener and the music. A further benefit of the inky black silence of this design is that there is more audible information available to the listener. Quiet notes, breathing noises, sound reflected off the walls of the recording venue, the subtle sound of fingers sliding along the metal or nylon strings of a guitar, the gentle thud of a mallet against the skin of a kettle drum - these are the sounds which contribute to the eerie sense of actually being physically present during the peformance. But Chapter Two is capable of combining this uncanny transparency with convincing musicality. It does not dissect the music in an overly analytical manner in the way that often occurs with too many conventional solid state designs. Chapter Two is simply more like "the real thing" than the very many competing amplifiers I have heard to date. It also has the essential ability to suppress noise arising from the programme material as well as the other components further down the component chain. The best valve amplifiers are particularly good at separating the programme material out from the various kinds of accompanying electronic noise. Solid state circuits, however, frequently exhibit a tendency to retain the noise and present it together with the music. Chapter Two behaves much more like a typical valve amp in this respect.
For me the Chapter Two means a farewell to valve power amps. Careful listening with other trained listeners over several months have persuaded me that here, for the first time in an affordable product, do we have an amplifier for the reproduction of music signals that combines the naturalness and organic wholeness of the finest valve circuits with the speed, control and reliability of solid state. Also, it is extraordinarily even-handed in its reproduction of the whole frequency range; no part of the audible frequency spectrum is exaggerated or neglected. It simply exhibits the most perfect top-to-bottom coherence of any amplifier in my experience. Some of the prestigious transistorised juggernauts often exaggerate the bass and accentuate macrodynamics, thereby sounding superficially impressive. But real, unplugged music is not like that at all, of course. The Chapter Two impresses through its very relaxed and natural presentation of any signal it is asked amplify. That is why I and everyone else I know who has enjoyed music through this English amp has simply been able to forget that it was in the system at all. The more I listen to Chapter Two, the more I become convinced that the thermionic valve is no longer indispensable for sheer musical involvement. For the past quarter of a century I have listened to countless valve amplifiers (Audio research, Conrad Johnson, GRAAF, Melos, Aronov, Lumley and others) in my own system. Since Chapter Two does everything well that valves do particularly well, while in addition possessing more sheer muscle than anyone will ever need, the Chapter Two has enabled me to bid a final farewell to valve power amps for my own use.
Some final thoughts
Chapter Two weighs no more than 16kgs and is very modest in size (437Wx135Hx300D). I have never been able to make it run hot. At most it becomes comfortably warm to the touch after many hours of driving heavy speakers - usually it remains lukewarm when used with speakers of moderate-to-high sensitivity. This means that heat is no issue in this case and the amplifier should be assured a longer-than-average operating life. Over the six months that the test specimen has been in operation it has performed flawlessly. This bodes well for its reliability.
Nor is noise an issue here. Switched mode power supplies are supposed to be noisy. The noise aspect is non-existent in this design. When you put your ear right up to the various drive units you hear nothing - no mains hum or buzz or hiss, just silence. This was a revelation for a valve enthusiast like myself, and it is just one more reason why I am determined to use the Chapter Two for my own musical pleasure - and as the benchmark against which other power amplifiers will have to be judged in the future. This is an addictive product, and those here in Norway who have been able to borrow a unit for a few days' audition in their own systems have not been able to part with it.
Chapter Audio is about to introduce a preamplifier to match the Chapter Two. If it is as musically satisfying as the Chapter Two, it will also be possible to live happily without a valve preamp. I just cannot wait to hear it . . .
EYEFI magazine, Norway
The Chapter Two switched mode power amplifier
Once in a while there appears on the audio firmament a component that is destined to become a classic from the moment it is launched. Chapter Audio in England happens to have created such a benchmark product.
As a music lover and audio critic I have been listening to hi-fi equipment for the past forty years and my own personal listening has been via valve equipment for more than twenty five years. For those of us who use live music as the only valid criterion on which to base the evaluation of recorded music - analog or digital - good valve amplifiers are generally felt to deliver the most believeable and enjoyable reproduction of the sound created by musical instruments. Even though many successful modern solid-state designs, such as Mark Levinson, Krell, Classé, Rowland Research, Goldmund etc, have impressed me with the sheer power and solidity of their performance, I have so far always preferred to return to the more relaxing naturalness of my own valve amplifiers. A properly implemented valve design has the ability to render the richness and complexity of instrumental timbre, so that a recorded and amplified human voice sounds more truly "human" and instruments simply sound more convincingly like themselves. Among the many other virtues of valves is their superior ability, in my opinion, to replicate with greater accuracy the three dimensions of sonic images resonating in a three-dimensional acoustic space. Too many solid-state designs are less holographic than valves because they often tend to flatten instruments and voices, even if modern transistorised amplification successfully recreates the depth of the recorded soundstage. Valves are also particularly successful in rendering the most subtle microdynamic gradations of a recording as well as other low level sonic cues within the recording venue. It is such essential details which contribute to the credibility of the musical illusion which we are trying to experience through the playback of our analog or digital sources.
It cannot be denied, however, that the most sophisticated solid state circuitry today is in many ways approaching the ability of valves to render both instrumental timbre and the three-dimensionality of sonic images. The gap between transistors and valves is closing fast. But it also has to be said that valve designs also have improved substantially over the past decade so that we have a situation now at the beginning of the millennium where there is healthy competition between both approaches to amplification. However, valves have a few undeniable generic weaknesses: they are inefficient, run hot, they often have a short life and vary in reliability. They are usually noisier than modern solid state devices and high output valve power amps are also prohibitively expensive.
The best of both worlds
Congratulations to Chapter Audio for having implemented and brought tomarket a real-world power amp that combines the most desirable virtues of both solid state and valve amplifiers. I have been able to listen to the incredible Chapter Two switched mode power amplifier at regular intervals for the past six months. Together with an experienced team of music lovers I have had the pleasure of evaluating the quite extraordinary performance of the Chapter Two in four carefully calibrated high-end systems using every conceivable kind of programme material from Presley to Purcell, from Hodges to Horowitz, from Madonna to Mahler. To put it simply: this amp is equally at home with everything you might care to throw at it. It doesn't have any identifiable signature, it doesn't sound like valves and it doesn't sound like transistors. It simply sounds like "music". And not only does it reproduce all types of music equally well, it will drive any kind of speaker type (and load) imaginable, from high-sensitivity horn systems to the most insensitive speakers. My favourite speaker is the beautifully crafted Sonus Faber Amati from Italy. It sounds more like a musical instrument than an electromechanical transducer. More than any other speaker used during the test it was capable of showing what an amazingly subtle and nuanced amplifier we were listening to. With a rated output of 200W into 8 ohms, or 400W into 4 ohms, and with its ultra-fast switched mode power supply - it recharges itself 1000 faster (!!) than any conventional amp - it drove the Amatis with such effortless ease that I could have sworn we were listening to a cross between a supercharged single-ended triode amp and a pair of hideously expensive Krell monoblocks. On the same speakers, and using the Conrad Johnson Premier 16LS linestage, we were able to carry out an A/B comparison test between the Chapter Two and the far more costly Sonic Frontiers Power 3 Special Edition monoblocks powered by a grand total of (very hot) 16 KT88s. Both power amps delivered a palpable and utterly natural midrange, but the Chapter Two had a slightly tauter and more extended bass. Both had a sweet treble, but I preferred an even purer and airier treble that seemed to extend for ever when we used Chapter Two.
The Chapter Two also showed its paces in another system consisting of a Hovland HP1 preamp and the JM Labs Mezzo Utopia speakers that, despite their fairly high sensitivity, are a little hard to drive and can tend to sound just a little sluggish in the bass. Again, the Chapter Two performed with conspicuous ease and the Mezzo Utopias took on an irresistibly rhythmic drive and an unexpected light-footedness that was not in evidence with either the Chord FPM 1200C or a Conrad Johnson 2300, both solid state designs used for comparison purposes.
What finally won me over completely was the way Chapter Two convincingly and unexpectedly outperformed my own reference amp, the Italian GRAAF GM 100, an elegant OTL design that has so far remained my personal favourite. Alas, the Chapter was to change all that! My custom-made speakers, using ESS 12" bass and 8" midrange drivers supplemented by the Heil EMIT tweeters, are mercilessly revealing of everything fed into them. The one CD that really illustrated the shockingly superior transparency of the Chapter Two was an old recording, transferred from LP to CD, by the distinguished pianist Rosalyn Tureck. This CD reissue of her complete set of the Bach Partitas (Polygram 456 976-2) was originally made for EMI in the late 1950s. Hers is an outstanding performance, but the CD has always sounded somewhat veiled and with a bit of noise, inevitable in such an old recording. The Chapter Two, with its startling clarity actually managed to lift several veils away from the recording and with its greater incisiveness and transient attack, it brought Rosalyn Tureck's Steinway out of the sonic murk of the old recording and brought it to startling life. I can only attribute this audible improvement to the outstanding clarity, speed and energy of the English amp which imbued Miss Tureck's performance with the life and presence that it must have had originally, but which my slower and noisier valve amp had been incapable of reproducing.
A farewell to valves
The Chapter Two has revolutionised my attitude to solid state amplification. It is completely free from such traditional solid state artefacts as grit, grain and glare. Its absence of perceptible noise in any part of the audible frequency range - no mains hum or treble hiss - and its startling clarity and lucidity and its wonderfully relaxed, effortless reproduction of dynamic peaks and massive crescendos, are qualities that make this the easiest amplifier I have ever listened to in my own, or any other system. In addition to this, it possesses in full measure the natural warmth, rich timbral balance and holographic rendering of instruments and voices so that you sometimes feel you can somehow "see" around them. The rendering of razor sharp transients and almost inaudible low level information, obscured beneath the noise floor of lesser amplifiers, are other virtues of the Chapter circuitry and power supply that you immediately notice on first hearing this amp. In other words, there is much less that gets between the listener and the music. A further benefit of the inky black silence of this design is that there is more audible information available to the listener. Quiet notes, breathing noises, sound reflected off the walls of the recording venue, the subtle sound of fingers sliding along the metal or nylon strings of a guitar, the gentle thud of a mallet against the skin of a kettle drum - these are the sounds which contribute to the eerie sense of actually being physically present during the peformance. But Chapter Two is capable of combining this uncanny transparency with convincing musicality. It does not dissect the music in an overly analytical manner in the way that often occurs with too many conventional solid state designs. Chapter Two is simply more like "the real thing" than the very many competing amplifiers I have heard to date. It also has the essential ability to suppress noise arising from the programme material as well as the other components further down the component chain. The best valve amplifiers are particularly good at separating the programme material out from the various kinds of accompanying electronic noise. Solid state circuits, however, frequently exhibit a tendency to retain the noise and present it together with the music. Chapter Two behaves much more like a typical valve amp in this respect.
For me the Chapter Two means a farewell to valve power amps. Careful listening with other trained listeners over several months have persuaded me that here, for the first time in an affordable product, do we have an amplifier for the reproduction of music signals that combines the naturalness and organic wholeness of the finest valve circuits with the speed, control and reliability of solid state. Also, it is extraordinarily even-handed in its reproduction of the whole frequency range; no part of the audible frequency spectrum is exaggerated or neglected. It simply exhibits the most perfect top-to-bottom coherence of any amplifier in my experience. Some of the prestigious transistorised juggernauts often exaggerate the bass and accentuate macrodynamics, thereby sounding superficially impressive. But real, unplugged music is not like that at all, of course. The Chapter Two impresses through its very relaxed and natural presentation of any signal it is asked amplify. That is why I and everyone else I know who has enjoyed music through this English amp has simply been able to forget that it was in the system at all. The more I listen to Chapter Two, the more I become convinced that the thermionic valve is no longer indispensable for sheer musical involvement. For the past quarter of a century I have listened to countless valve amplifiers (Audio research, Conrad Johnson, GRAAF, Melos, Aronov, Lumley and others) in my own system. Since Chapter Two does everything well that valves do particularly well, while in addition possessing more sheer muscle than anyone will ever need, the Chapter Two has enabled me to bid a final farewell to valve power amps for my own use.
Some final thoughts
Chapter Two weighs no more than 16kgs and is very modest in size (437Wx135Hx300D). I have never been able to make it run hot. At most it becomes comfortably warm to the touch after many hours of driving heavy speakers - usually it remains lukewarm when used with speakers of moderate-to-high sensitivity. This means that heat is no issue in this case and the amplifier should be assured a longer-than-average operating life. Over the six months that the test specimen has been in operation it has performed flawlessly. This bodes well for its reliability.
Nor is noise an issue here. Switched mode power supplies are supposed to be noisy. The noise aspect is non-existent in this design. When you put your ear right up to the various drive units you hear nothing - no mains hum or buzz or hiss, just silence. This was a revelation for a valve enthusiast like myself, and it is just one more reason why I am determined to use the Chapter Two for my own musical pleasure - and as the benchmark against which other power amplifiers will have to be judged in the future. This is an addictive product, and those here in Norway who have been able to borrow a unit for a few days' audition in their own systems have not been able to part with it.
Chapter Audio is about to introduce a preamplifier to match the Chapter Two. If it is as musically satisfying as the Chapter Two, it will also be possible to live happily without a valve preamp. I just cannot wait to hear it . . .
