This review page is supported in part by the sponsor whose ad is displayed above
Reviewer: Srajan Ebaen
Source: Zanden Audio Model 2000P/5000S; Ancient Audio Lektor Prime
Preamp/Integrated: Supratek Cabernet Dual; Melody Valve HiFi I2A3;
EQ: Rane PEQ55 active merely below 40Hz on Zu Definition Pro
Amp: 2 x Audiosector Patek SE; Yamamoto A-08S; Eastern Electric M-520 in power amp mode, Anthony Gallo Reference SA amp/xover/EQ
Speakers: Zu Cable Definition Pro in custom lacquer; WLM Diva Monitor, Duo 12, Pre/Passive and Bass Control, Alto Mac 2.2 sub amp
Cables: Crystal Cable Ultra loom, Zanden Audio proprietary I²S cable,Crystal Cable Reference power cords; double cryo'd Acrolink with Furutech UK plug between wall and transformer; AMR analog interconnect and one power cord on CD-77 [on review]
Stands: 2 x Grand Prix Audio Monaco Modular four-tier
Powerline conditioning: 2 x Walker Audio Velocitor S fed from custom AudioSector 1.5KV Plitron step-down transformer with balanced power output option
Sundry accessories: GPA Formula Carbon/Kevlar shelf for transport; GPA Apex footers underneath stand, DAC and amp; Walker Audio Extreme SST on all connections; Walker Audio Vivid CD cleaner; Walker Audio Reference HDLs; Furutech RD-2 CD demagnetizer
Room size: 16' w x 21' d x 9' h in short-wall setup, with openly adjoining 15' x 35' living room
Review Component Retail: £4,399 | $8,500 each
The launch of a new audio company. First introductions.
Caligula is dead. And his successor ain't a horse. Sorry. That seems a fitting opener for announcing today's subject matter. You see, besides being completely mad, Caligula was also known for excess. Two codependent conditions perhaps. Much of cutting-edge High-End audio pricing exhibits similar madness. Blame the joint tyranny of lack of scale and sales. Abbingdon Music Research -- AMR for short and a subsidiary of the Abbingdon Global Group -- was specifically launched to reintroduce a degree of sanity without relinquishing a properly fiendish grip on extreme performance. To strip Caligula of his madness, AMR adapts NAD's original recipe and that of many others since: design in Europe, manufacture offshore. Except not quite. For one, unique control mechanisms are in place to assure top quality. We'll learn more about that in a moment. For two and relatedly, AMR pursues UltraFi, not the mid sector that's far more typical of such endeavors. UltraFi becomes obvious the moment you lay eyes on -- and your lower back into -- the CEC-reminiscent cosmetics with their champagne gold or dark titanium skins and the sheer heft of the firm's first components, the CD-77 and AM-77. Once you read up on design details and implementation, the phrase madly ambitious suggests itself. But let's start at the beginning.
"Our basic premise was simple: to have single-box devices with universal compatibility that would suit normal people as well as rightsizing audiophiles." So did Thorsten Loesch, my company contact, paraphrase their mission manifesto. Abbingdon Music Research was founded in 2001 by Mr. P. Wayne, Mr V. Luke and Mr. T. Loesch. In 2003, the founders were approached by a group of investors who had learnt of AMR's vision and research. Impressed by the company's stance and products under development, the investors provided substantial additional funding. This not only strengthened the company but eliminated the budgetary and time table constraints from the design process which are otherwise imposed by modern economic cycles. Instead, AMR "took the time to thoroughly design and execute Ultra-Fidelity components reminiscent of the Golden Era of HiFi - 1950 to 1970". Five years in fact.
Chief Executive and Director of Operations is Mr. Wayne who used to be a senior design engineer with two prominent telecommunication firms, has extensive experience in digital circuit and communication networks design and developed various unconventional digital circuits. His forte is the fundamental design of digital to analogue chip sets. Together with Mr. Loesch, he is one of the most knowledgeable designers on the vaunted Philips TDA1541A platform.
Executive Director of Marketing Mr. Luke spent 11 years in the US and UK investment banking industries. His passion stems from having analyzed the background of numerous companies and industries and applying this to his pursuit of audio designs and components. Well-versed in human engineering, "Mr. Luke ensures that every AMR component is not merely a technological tour de force but also excels in aesthetics and ergonomics".
Executive Technical Director Mr. Loesch has contributed to various online audio magazines over the years, worked as pro-audio designer and sound engineer and entered many a highly regarded audio design into the public domain. One particular creation of his -- in cooperation with transformer manufacturer Stevens & Billington -- has been the commercial application of his intimate understanding of Western Electric designs, namely the transformer volume control based on 1930's WE designs which sparked the present resurgence in passive attenuation devices. At AMR, Mr. Loesch led the in-house design team that brought the AM-77 and the CD-77 to market and is presently engaged in several new and exciting AMR projects, including the PH-77 phono stage. The 2-way aluminum-clad LS-77 speaker with TL porting is already completed. It's claimed to cover 28Hz to 40kHz and showed in prototype form at the fall 2006 London show.
AMR presently employs 18 staff members. Divided between the UK and overseas, the staff based in the UK is the research & design team and the firm's front-end. The overseas staff is located at AMR's modern manufacturing facilities, subcontracts exclusively with aerospace-standard approved sources and is headed and supervised by Mr. Wayne to ensure stringent compliance with "all sourcing of materials, assembly, testing and quality control (all in-house)." This is clearly where AMR's recipe departs from the one New Audio Dimensions pioneered. It's not about outsourcing per se. It's about structuring oneself as a bi-continental company with full control over all aspects regardless of location.
I imagined out loud that AMR's formation with this rollout of products must have entailed its fair share of complexities. Thorsten merely shrugged it off. "We are happy to have gotten things done and to share our passions and the fruits of our work with others." While I had Thorsten's ear, I asked about the legendary Philips TDA 1541A 'King of the Multibit' chip in his one-box CD-77. In select Double Crown flavor, it currently shows up in Zanden Audio's award-winning Model 5000 Signature converter. Hadn't this vintage chip gotten exceedingly rare? "Yes, though recently a few hundred alleged Double Crown chips have turned up again. Double Crown chips were selected for best linearity. Slightly worse linearity made them Single Crown. The rest (which of course still met the specifications) were the normal uncrowned ones.
"We actually analyzed the TDA1541A on an internal circuit level in extreme detail. In the process, we discovered a number of areas where correctly designed external circuitry can help to reduce the difference in linearity between the Crown and standard chips. I hope you understand that I do not wish to cover the exact details in any length. This was a research project that began in 2000 when I had published my 1999 TDA1541 non-oversampling DAC. As a result, I was provided with extensive notes (one very large and thick map of paper) on the internal design of the TDA1541 by a kind engineer at Philips Eindhoven.
"The technology that resulted from these investigations we call the OptiSignal conditioning circuit and OptiClockLock. These help to considerably bridge the gap between standard TDA1541s and Double Crown chips in our trials, both on measured and subjective performance (I own several Double Crowns). The result is also much better than my original Adagio design fitted with a genuine Double Crown chip. And better than the legendary Marantz CD-12 DAC (I used to own the Philips LHH-1000 version). Or at least we think so. We bought a rather large consignment of chips quite a few years ago (as well as NOS valves). I also have on the drawing board a discrete DAC which will incorporate some of the principles of the TDA1541 but with a 24-bit word length [the 1541 is 16-bit - Ed.]. It will however not be a priority to push this ahead until we sell out of TDA1541s. With our secured rare vintage inventories, this won't be any time soon."
The 20-year vintage of the chip means external digital and analog filters. They offer the equipment designer open choices unlike today's integrated chips that combine everything on one sealed die. AMR thus mates this 16-bit converter to an advanced Texas Instruments DSP (digital signal processing) and CPLD (complex programmable logic device) engine. This nets user-selectable options via one-button remote command. The choices are "Digital Master I without any filtering or processing; no digital filtering but AMR's proprietary analogue filter aka Digital Master II; two and four times oversampling; or upsampling to 96 and 192kHz respectively."
AMR addresses digital noise and resultant jitter with clock synchronization to a temperature-compensated, low-jitter master clock module with its own dedicated power supply. Based on military specs, this clock generator is temperature invariant and claimed to only have one commercial competitor of similar sophistication - the K2 XRCD studio mastering system by JVC (on which of course the famous Harmonix/Reimyo one-box player was based).
Equivalent cutting-edge performance is claimed for the digital power supply. It filters into the GHz range by using 14 discrete and dissimilar regulators ("series regulation, shunt regulation, all optimized for lowest noise and lowest impedance etc. depending on exact stage"). Those "reduce power supply noise by a factor of more than 1000 times compared to standard regulators. This results in the virtual elimination of digital noise." The top-loading transport is a proprietary amalgamation of Sony's Japanese K-series transport, Philips' CD-18 servo system and a high-torque, direct-drive Japanese Mabuchi motor, all housed inside a very substantial CNC machined aluminium CD well with a sizeable CD spindle for 250% more surface area underneath an in-house designed CD clamp.
AMR's analogue output stage isn't a mere tube buffer with preceding op amps either. It's a from-the-ground-up zero-feedback, high-gain, low-Z, direct-coupled all NOS-valve circuit with one ECC81/12AT7/6072A per channel for gain, one 5687 per side in the output and dual-mono thermionic rectification via a pair of EZ80/EZ81/6CA4. A USB input can interface a computer or portable WAV, AAC, WMA or MP3 files for playback conversion inside the CD-77. Yet there is no S/PDIF input. AMR feels it would suffer from higher jitter than a properly implemented USB receiver. The CD-77's sonic quality -- believed to deliver SACD sound from Redbook CD -- is deemed so superior that digital outputs are viewed as completely redundant. Hence they aren't provided.
For connectivity, the CD-77 offers the afore-mentioned USB input plus RCA and XLR outputs. Specs include a >2V max output voltage; an output impedance of less than 200 ohms (recommended load impedance 10Kohm or greater); 'A' weighted S/N ratio of >100dB; THD of <0.3%; dynamic range better than 90dB; and channel separation better than 100dB. Rated voltage is universal, from 90-135V and 190-260V, on 50/60Hz supplies. Dimensions are 17.8" x 6" x 18.3" WxHxD. Weight is an absolutely colossal 62 lbs (77 lbs in shipping container). Warranty is 5 years.
In case you were wondering, AMR chose the one-box route also for jitter reduction. Transmission and sync jitter are generated when transport and converter are separated. Costly and complex schemes then become mandatory to combat this jitter. That's a questionable and ineffective approach. What we have in the CD-77 is a Redbook-only player that mirrors core concepts from the award-winning, ultra-expensive and cutting-edge digital Zanden separates. In common with the Japanese designs are the actual chip; the filterless approach; the true valve-rectified, valve-driven output stage; an optimized top-loading transport; a temperature-controlled master clock generator; and superior chassis work.
The CD-77 then goes a few steps farther. It adds USB and DSP functionality to account for modern listening habits. And it reduces box count from 4 to 1. More serious even is the reduction of cost - from $43,440 to ca. $7,000. While that's still a very significant investment for most mortals, it's no longer stark-raving, burning-torches Caligula mad.
On to the AM-77 dual-mono integrated of which Vincent Luke is even more proud if that seems possible. This integrated amp can get user-configured as a stereo or mono power amp, a twin mono amp for biamping or sync'd in parallel. Its 180wpc 8/4-ohm heart is the two-stage OptiGain circuit (270 watts/8R dynamic power IHF standard). That's a 5687 zero NFB preamp stage followed by a tube phase splitter in front of a true differential class A bipolar power buffer that drives both speaker terminals actively. The balanced architecture allows feed-forward error correction instead of negative feedback. One of the two balanced phases per channel is extracted, phase-inverted and applied to the opposite phase feed. "This feed-forward error correction in effect completely removes the 'solid-state' sonic signature of the power buffer stage, leaving an amplifier that behaves sonically like an optimal, extremely high power (>180W) and very linear (0.09% THD @ 180W) single-ended triode amplifier with only two stages and a constant high damping factor (over 15 from 1Hz to 10kHz)." Claimed S/N ratio is better than 100dB. Power consumption at full rated output is a hefty 1000 watts.
The patent-pending and remote-controlled "direct path precision volume control system" is an active variation on the stepped attenuator. It inserts maximally three premium-grade series resistors into the signal path to control the volume. Highest-grade, hermetically sealed gold-plated silver contact relays act as switches, replace the rotary switches of conventional stepped attenuators and offer a range of seventy-one 1dB steps. Microprocessor-controlled level offset matching is integral to this solution. The end result -- as per AMR's claim -- is sonic quality exceeding the very best stepped attenuators with the convenience and flexibility of the best digital volume controls.
Transparent protection circuity addresses direct current, over-voltage, under-voltage, overload and over temperature scenarios. In an effort to eliminate common tuning-fork resonances, the 79 lbs chassis avoids heat sinks altogether. The power supply in conjunction with patent-pending OptiMains power conditioning eliminates the need for valve-stage regulation (regulation there is considered sonically compromised and thus undesirable) by instead using multi-stage, galvanically isolated passive filtering. This includes electrolytic-free choke/capacitor type filters and resistor/capacitor filters. The unique AC mains supply is said to render the signal circuity invariant to power grid voltage fluctuations, flat-topping under voltages and power-line RF contamination. This proprietary solution is considered superior to power-factor corrected switch-mode supplies and "as effective as so-called double conversion mains regulators". Side benefits are extended life span and reliability of tubes and other parts - plus universal mains voltage compatibility without any modification. Even the power transformer isn't an off-the-shelf unit but a custom hand-wound dual C-core 1200VA affair with extremely low flux leakage and noise radiation. It renders moot the need to segregate the power supply section offboard for best sonic results. As with the CD-77, the integrated one-box solution thus wins out as planned.
Golden-ratio relations in the chassis dimensions are said to undermine pronounced resonance patterns while solid copper plates sandwiched between outer enclosure and inner sections add further shielding and energy-absorptive qualities. The integral footers are custom-designed for maximum effectiveness. Premium parts overall include NOS valves, Mundorf and AMR film capacitors, Elna Silmic low-Z capacitors, advanced X2Y and PPS film surface mount capacitors and Sanyo OSCONs in digital sections; zero switching noise Schottky diodes; FEP Teflon-insulated hookup and flying-lead wiring; and military-spec circuit boards with gold-plated copper tracks said to be double the thickness of conventional traces. In short, the AMR engineers seemingly considered every single element and aspect of parts selection, circuit design and chassis fabrication. What's more, they developed proprietary (and in some cases patent-pending) solutions wherever necessary to make this combined product launch - well, madly ambitious.
Would you like to download the current image?