Jun 282010
 
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Ahead of the AMR CD-777 CD player review (due soon), I am very pleased to be able to republish this review that I wrote for the Art of Sound, featuring the AMR CD-77.
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This is a tale of three CD players all using the classic digital technology embodied in the Philips TDA 1541 DAC. This famous chip was very much the culmination of the Multi-Bit period of digital development during the late 80’s to mid 90’s and at the height of its use it formed the digital processing hub of many legendary CD players from such companies as Sony, Marantz, Cambridge Audio, Micro Seki, California Audio Labs, Naim, and many others to numerous to name here. So if this was the most popular DAC of its age, why then did its use end so suddenly? The simple answer as in many such cases was the cost of implementation. This was the main factor that saw this Multi-Bit period end, in favour of the introduction of the simpler/cheaper to implement, Single Bit or Bit Stream chip, until that too passed away, to be replaced by up-sampling technology and DACs made by Burr Brown and Analogue Devices, to name but two of the more commonly used modern DAC brands.
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When the Philips TDA 1541 DAC  ruled in all its various versions (best to worst-TDA1541A-S2,TDA1541A-S1,TDA1541A-R1,TDA1541A), many felt that digital had reached the heights of what it could then achieve, but as with all things that opinion changed and was replaced by a consensus of opinion that while it  had been good, it really wasn’t as good as some had stated. So why, many years later do many state that in fact this earlier assertion was correct ? Surely with digital, new and modern is best…. with technical progress comes improvement, surly that’s true, isn’t it ? Well among a small number of audio designers and the companies they work for, or own that would appear not to be the case anymore.
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The first blast from the past happened in 1999 with the reactivation of the classic model number 7; classic that is for Marantz. The Ken Ishiwata designed Marantz CD 7 used a set of TDA 1541 Double Crown DACs in a dual differential layout (a design first revealed in the CD 94 mk2 and CD 12, both highly regarded vintage Marantz players) and this essentially vintage design (in terms of technology, if not actual age) received glowing reviews and was haled as a landmark design; a far cry from being hailed as being redundant.
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However far from being a swan song and a last bright flash from the past, a small number of other companies have continued to design to this day CD players using this vintage technology; namely Zanden of Japan and  more recently Abbingdon Music Research, or AMR for short. Rather than seeing Multi-Bit as a technology fit only for the great audio dustbin of history, marked redundant technology,they instead see great advantages in continuing on with the TDA 1541.
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I had intended originally that this review be mainly focused on the newish AMR-CD77 CD player but it occurred to me, that broadening the review remit out to include a comparison of the best examples of Multi-Bit technology to the AMR player would make for a much more complete review. The review would now not only discover how good the AMR is in a current context but also discover how well it fits into the history of Multi-Bit designs overall.
Now this is not a fully comprehensive overview, as to do that I would have needed to include the best Multi-Bit designs from say the likes of Sony or Cambridge Audio but I am sure that no one can gainsay the quality and reputation of the other players I am comparing the AMR CD-77 to, namely the Marantz CD94mk2 and the Marantz CD7.
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So let the fun and games start, up first the…..
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The AMR CD77.
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History, goals and technology….
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Abbingdon Music Research or AMR under the leadership of Mr. P. Wayne,Vincent Luke ( I once went to dinner with Vincent after a HiFi show and I  found him to be very passionate about music, AMR and generally a very nice guy) and Thorsten Loesch, have sought to introduce a range of products designed in the UK and made of shore (China) but instead of being constructed in a third party factory (often creating major quality control issues), AMR products are being made by a factory owned wholly by and controlled by the parent company, namely the Abbingdon Group, thus guaranteeing the very highest production quality.
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Unlike many new companies developing new products, a massive injection of cash early on in the project has allowed AMR to take its time in bringing its designs to the market; a total of five years; this is a very long time in audio. With Mr Wayne who is an expert in digital technology and one of the most knowledgeable at implementing the TDA1541 DAC, Thorsten Loesch; these gentlemen both worked on the idea that was to became the AMR CD-77.
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Thorsten talks here about the design process and how they achieved double crown performance from a standard TDA 1541 A DAC, rather than the S1 Crown version.
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“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 . 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]. 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.” (1)
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The passage above outlines the key to the success of the AMR CD-77, and as Thorsten explains the “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.” (2), it is these that AMR use in their design and have pushed the boundaries of the performance envelope of the basic chip to way beyond the Double Crown spec.
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Other aspects of the design are equally high in concept and execution. The digital power supply filters into the Ghz range by using 14 discrete and dissimilar regulators. This approach gives excellent rejection of digital noise and it is claimed by AMR removes it almost completely.
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The top loading mechanism is an amalgam of the K series Sony transport, with a Philips CD-18 servo system and high torque, direct drive Mabuchi motor. A larger than normal support hub spindle supports more of the CD being played and a beautifully made clamp secures the disc to this substantial design. The transport is also isolated from the internal structure of the player by isolating springs like the shocks in a car.
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Analogue output is via a zero-feedback, high-gain, direct coupled NOS valve circuit with a dual mono (not balanced) layout. Each channel has an EEC 81 for gain, a 5687 in the output and valve rectification in the form of a EZ80.
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The rear panel of the player includes XLR outputs (these are not balanced. While the internals are laid out to either side of the transport as a separate left and right, the AMR is not a dual differential design; so not balanced) and the superior sounding RCA outputs. A USB input is included so PC audio would benefit as the CD-77 can be used as a DAC for this application (not tested). Sadly there is no digital output, because the designers felt that including this function would reduce the sound quality ( this was true of the first production version which forms the basis of this review but with the more recent version, an option exists to have a spdif digital in and out via a coax connection) . The designers also decided on a one box design, rather than a two box transport and DAC design,in order to reduce jitter which can occur with twin box designs.
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One of the aspects of this design I loved on first seeing it, was the remote control. Call me sad but the blue glow of the soft touch screen had me seduced from the off. With this substantial remote it is possible to control an AMR amplifier and all the functions you would expect to get with a CD player. However there are functions included here you would not expect to get normally and the most notable one of these is the ability to switch between filtering and up-sampling and over-sampling as the machine is playing.
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The AMR offers two no-filter settings Master 1 and Master 2 as well as 2 and 4 times oversampling and 96,192 kHz up-sampling. This is exciting stuff indeed.
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Overall build quality is very good but not perhaps as good as some of the Japanese designs from Esoteric, Accuphase and the like, but compared to most UK products; the level of fit and finish is very good indeed. The player comes in a flight case (with the player snug inside and it’s a two man lift) and included in the robust packaging is a high quality mains lead, Nordost style interconnect , CD of classical music and a run in disc (this is vital as I will reveal later). The AMR player is massive and you will need to site it on a robust top shelf, both because of its massive size but also as it is a top loading CD player. All in all an amazing product and presentation.
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The Review….

This review was originally intended to be just about the AMR CD-77 but as mentioned earlier, having also to hand two excellent past TDA 1541 designs I thought that rather than compare the AMR, to say my Moon Andromeda it would be more interesting to compare it to its fore runners, in the form of the Marantz CD7 and the Marantz CD94mk2. This would prove to be very interesting indeed.
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What I hoped to do, was get a handle on just how much better AMR’s design choices were over Marantz’s and see if the AMR implementation of Multi-Bit technology offered anything new; or would it just be a rehash of the old and offer a similar standard of sound. The AMR CD-77 being reviewed is mine and I have owned it for quite awhile now (it was one of the first two full production models available in the UK at the time I bought it), but I had never taken the time to compare it with the older Marantz designs. Would it be as good or better ?…..we shall see !
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The review system…
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The review system was the BAT VK 31 se pre-amplifier, BAT VK 75 power amplifier, Anthony Gallo Ref 3.1 speakers. Cabling was Atlas Marvos and Audience Au 24 both in RCA and XLR types and speaker cable. The isolation tables were Clearlight Audio, platforms Base and String Suspension Concept designs. Also used Ringmat Isolation Feet, RDC Cones and AMR Isolation feet. No mains filters or regenerators were used during these tests. However both Audience, TCI Boa Constrictor and Analysis Plus power Oval2 mains cables were used.
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During the preparations for this review, I rediscovered the vital requirement to allow these Multi-Bit players enough warm up time and indeed as a result of this particular review I now feel that up to 4 weeks is really needed for this to be complete. I know this is a somewhat controversial statement but to my ears, and in the context of this system, that is the conclusion I came to.
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I used to feel with Marantz Multi-Bit CD players that a week was enough time to achieve this, and while I knew the AMR needed more time, it is now clear that all sound much better and noticeably so, after a period of at least a month of being on and used.
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Run in is a different issue and indeed the AMR is a bit of a pain in this regard. Its poor out of the box and when I had originally bought it I must say I felt I had made a mistake buying it. The promise was there but not really evident until at least 2 weeks of solid use had gone by, and even then, it still wasn’t that good. In my experience this player needs a whopping 2 months of run in and even then it still improved a wee bit more after a further few weeks use.
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Once again the importance of full run-in and burn-in before reviewing or even before deciding if an item is truly happy in your system was brought home to me. So before you ever dismiss any product in your own system, make sure it’s fully run in….even if you don’t believe in it, try it none the less.
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I am sure some of you might be tired reading about the same music that I use during my reviews ( I have mentioned before the importance of using familiar music during any review), so while I did use these during this review, I will mostly talk about an album by a group called Slovo.
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Slovo are an Electronic dance/pop act fronted by Dave Randall and Andrea Britton and their second album Todo Cambia like the first is very well recorded. The music in feel owes a bit to the sounds of Massive Attack, in so much as it features rap and both male, and female vocals. The album is on the brixtown label and it’s code number is brx007. I  used the tracks, Being You and On the Bus.
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The changes in sound apparent with this music was also apparent with the Hugh Masekela track Stimela (The Coal Train) and Nitin Sawhney-Beyond Skin album’s tracks, that I have mentioned before (Tides, Broken Skin,The Pilgrim and Nadia).
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During preparations for this review, I had tried a few isolation experiments with the Marantz CD94mk2 and the Marantz CD7 in order to squeeze as much performance as I could from what ever source I could. In the case of the CD94mk2 these experiments resulted in the player sitting on three cones which in turn rested on three Ringmat Isolation Feet……. The Marantz CD7 ended up with three RDC cones under it. One placed under the middle of the transport, one under the mains transformer and one to balance it.This simple act transformed the sound of this all ready excellent machine as had the placement of Ringmat Isolation Feet under the CD94mk2.
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During the course of this review another assumption was challenged. I had been happy with the way that I had my CD7 set up and I did not think I could squeeze any more out of it over and above what I had already.  How wrong was I ? Lots but more on this latter.
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With the improvements in sound that the two Marantz CD players had undergone, I now felt able to work from a level playing field in regard to the cabling I would use during the review. The Marantz CD players had both sounded better with Audience AU24 interconnects before tweaking. However now I was able to use Atlas Marvos through out, a state of affairs that guaranteed a level base, during the review. I did not have to factor in any changes as a result of cable differences, as a single brand cable loom was now in use. Satisfied I could not optimize things anymore, I got down to the serious job of comparing and contrasting.
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First up was Being You on the AMR CD-77. I decided to start at the top (assumed top, as I had actually never compared any of these players directly before.) and the sound that came forth was amazing. Being You starts with the voice of Rhianna Kenny, accompanied by an upright double bass. The vocal was solid, clear and very real sounding. Just before she begins to sing the acoustic of the recording studio( real or created ?) filled the space between and outside the speakers. As she sings the double bass began to play and it was reproduced with just the right degree of body and woodiness. The instrument had a presence in the room as if it was there. As the other instruments came into play with Andrea Brittons backing vocals the level of detail retrieval was breathtaking, as was the focus, coherence and clarity.
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This sound was not etched or spotlit at all, in fact it sounded natural, like music and not hi-fi. The artificial forwardness that some CD players produce was absent and a wholly coherent, indeed organic sound filled the room. Sounstaging was also excellent with superb image height and depth. Width of image was not as far beyond the speakers as my Moon Andromeda, but was still very good indeed.
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Being You is an extremely emotional track and the AMR captured this perfectly…” So try to be strong now. Keep struggling on now. And when your heart is true. Whatever else you do. Just keep being you.” Rhianna’s voice and the ebb and flow of the track had me nearly in tears. Part of the AMR’s success in doing this must lie with its high level of mid-range focus. Male and in this case female vocals just sound real and natural and very three dimensional, with a reach out and touch quality; that only vinyl normally has.  In fact the entire sound field has this amazing solidity. The AMR’s rendering of each element in its correct place and space, producing a three dimensional entity in the room. The music also ebbed and flowed with great timing and pace and during the more up tempo moments I found myself tapping my foot in time with the music. All in all Being You was so good I listened to this track again.
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Next up was On the Bus, this track is more spartan than Being You, featuring Andrea Britton on vocals and Dave Randall on guitar and keyboards. This song has a majesty and grandeur revealed in a gentle and delicate way. A hard task to reproduce but the AMR CD-77 rose to it with aplomb.
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Andrea’s beautifully breathy seductive vocal stood stage front, solid and bold with Dave’s guitar playing rising and falling, accompanied by waves of keyboards; the overall effect was haunting. All this detail as before was rendered in such away as to be coherent and very focused and again no instrument was spotlit. Its quite an achievement to be able to create a very highly detailed soundstage populated with a throughly believable performance, but one that does not scream and shout “look at this frequency, look at the bass etc” the AMR just gets on with it producing real music not hi-fi fireworks. As I write this I wish you could have been here to hear this magical sound. I was tempted to listen to the whole album but disciplined myself and placed Slovo in the tray of the Marantz CD7.
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Marantz  CD7……
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Now I must be honest here and say that I had done some listening before sitting down to do the review properly and the sound with the CD7 at that time was not as it was on the main day. In fact both tracks were very poor compared to the AMR; much more so than I had expected.
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The CD7 sounded open and detailed but had a presentation that was….well frankly more about Hi-Fi than music. Sitting wondering about this I thought about using a similar method to isolate the CD7 as I was using on the CD94 mk2 (sans Ringmat, as I do not have two sets of Ringmat isolation feet). I opted to place instead three RDC cones under the CD7. One placed central to the Laser mechanism, one under the mains transformer and one to balance the player. This arrangement was almost identical to the position of the cones under the 94 mk2. I placed a disc in the drawer, hit play and moments later my open mouth nearly hit the floor. Gone was the spotlighting and Hi-Fi fireworks to be replaced by music.
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With the CD7 Being You and On the Bus gained much of the AMR’s qualities but not quite. The sound now had body and some of the CD-77’s organic coherence but it lacked the mid-range focus, clarity and detail. The soundstage was a tad bigger, but with Being You the emotion quotient was ramped down and frankly not as moving. A touch of leanness was present in the sound, not as obvious as before and indeed the best way to describe this was to say it sounded solid state to the AMR’s valve qualities.
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The bass was tight and extended but lacked the weight and body on the double bass on the track Being You as reproduced by the AMR, but I can see some preferring this slightly leaner sound, say in a system that errs too much to the heavy side of things. However the CD7 cooler take on things made it hard for me to get emotional on this track. On the Bus was very good but lacked the magic of the CD-77.
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Marantz CD94mk2….
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I was now prepared for the Marantz CD94 mk2 to get its butt kicked big time, being the pensioner here but I was shocked and stunned by what I heard instead; I preferred its sound to the CD7. It was not as good in many areas such as the upper treble and it lacked detail, but it gave up nothing in the bass, in fact it was better here than either the CD7 or AMR player.
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The CD94 mk2 sounded like the AMR, it had bags of emotion on Being You and reproduced On the Bus in a similar way, but it was with the shimmer and decay of cymbals that it fell down, the AMR wiping the floor with it. It also lacked clarity and focus but despite all this it made music and wow what a good soundstage it produced, lacking depth to the AMR but being as wide and deep as the CD7.
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In terms of tonality the CD94 mk2 bears a striking resemblance to the AMR CD-77 sharing its warmth and organic presentation and despite the latter having a valve output stage, and the former being solid state; both sound valve like to the CD7’s solid state.
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Listening to the CD 94mk2 was a salutary reminder that there is more to listening and enjoying music than ultra-detail-retrieval and those other things which many audiophiles get wound up about. However at the end of the day the vintage Marantz was not as good, and by a large margin, but still was very enjoyable to listen to.
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The other area in which the CD 94 mk2 failed (but not totally) was in being able to produce a natural effortless reality, something the AMR did without breaking into a sweat.
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Conclusions…..
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This review/comparison has been fascinating and surprising, mainly in how excellent the 20 year old Marantz CD94 mk2 sounded, despite its flaws. I had not expected, despite the common root in the shape of the TDA 1541 DAC shared among the three players, that the AMR and CD94 mk2 would be so close in their fundamental sound and despite the major difference in sound how much I would enjoy it. Let me assure you who read this, this was not an exercise in  romantic reminiscing but an attempt to see if vintage digital is relevant today and for me the answer must be yes, with the qualification of how it was implemented. For a twenty year old classic to be so good was a revelation.
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The shock of the effect on sound of three RDC cones under the Marantz CD7 was also revelatory but despite this jump in sound quality it fell short of the magic of the CD 94 mk2, despite the CD7 being better in all the hi-fi categories. I must concede that some will prefer the CD7 to the AMR and Marantz CD 94mk2 but for me in this context I think the later two have it, with the AMR being perhaps, next to the Zanden’s CD players being the best commercial current implementation of the multi-bit TDA 1541 technology that I have heard to date. However at half the price of a Zanden, is that extra few percent worth the money? I don’t know, not having had the chance to compare a Zanden to the AMR CD-77 in my own system or anywhere else under controlled circumstances; I am sure you will agree that audio shows are not such an environment. On the 6 moons, the editor and chief reviewer has, and he felt it was a very close thing. He called the AMR CD-77 “ A zanden for the many “ high praise indeed.
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On a final note the AMR player has the facility to switch filtering etc during playback. I preferred the Master setting 2 to any other settings, but you can try them and see what you think. All of the listening was done with this setting in place and with the display switched off; it sounded a tad better this way.
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Was the AMR perfect….well no. The bass might just be a tad over fat in my system, but only slightly and this was perfectly acceptable to me. Other than that, its size maybe an issue for some ( I also felt, that in classic Marantz champagne finish the AMR CD-77’s bulk looked much better and less of a slab which it looks to my eyes in the grey titanium finish), as too is the fact that in standbye mode the blue inner lights are left on, what a waste of electricity (as pretty as this is and I do like it, I wondered if with these off , the sound could have been better…the answer to that remains unknown; except to its designers) One other small niggle was an occasional hum from the player, such things bug me big time as my system sits to the side of me and because of that I demand silence from my components. I should add that during playback this hum did not ruin music for me even during low level passages.
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In regard to sound I have no complaints and the AMR CD-77 in my view and I must stress that and despite the price hike over the last few years (£4500 risen to £7295) still remains excellent value for money. However the biggest bargain here might be the Marantz CD94, if you can live with its short comings…go on, its twenty years old; a veritable dinosaur in digital terms but still relevant today and who knows, with say an Audiocom modification; it might even turn out to be better than the AMR….ummmm thats an interesting thought.
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So overall my feelings are that there is life in old digital technology as embodied  by Multi-Bit in the shape of the TDA1541 DAC, even in a modern audio system be it a Marantz CD94mk2 (or perhaps a Marantz CD12 as well) or the bang up to date implementation by AMR, in their CD-77 CD  player, it is the best Multi-Bit CD player I have heard so far….well done Abbingdon Music Research, Mr. P. Wayne, Thorsten Loesch and Vincent Luke.
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Neil
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Source of Review Product Loan….. Reviewers own item.
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AMR CD-77 £7295 (now in a .1 version.  The player in this review is the older version first production version. I would suspect that the new improvements will refine this product even further)
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Current UK distribution for AMR products  Select Audio http://www.selectaudio.co.uk/
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Abbingdon Music Research http://www.amr-audio.co.uk/
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If you want more info on the TDA 1541 and possible mods for the Marantz CD94  see these links below….
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Quotes 1 and 2 copyright Thorsten Loesch.
Additional Photos of interest…..
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© Text and Photos Copyright 2010 Adventures in High Fidelity Audio…..except the AMR promotional photos, small Marantz CD7, Marantz CD 94mk2, TDA1541 DAC photos and album sleeve art.  Copyright belongs to their original publishers.
NB No part or portion of this article may be reproduced or quoted without written permission.
 Posted by at 11:58 pm

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