Futuristic Past - Passed Future?
by Wolfgang Vogel
The following is an English translation, by the author, of an article that appears in the November 2006 Issue 58 of the German audio magazine Hörerlebnis:
No Limits - Part 3: The Trio/Kenwood L-07D
Futuristic Past – Passed Future?
by Wolfgang Vogel
As if its creators had taken the blueprint from a science fiction novel, that’s how it looks. Should Lt. Uhura (from the original Star Trek series) have owned (will ever own?) a turntable it would surely have been this one. Captain Kirk would definitely have one, as well. Same with Dr. McCoy. Why? Because function and design were matched in an unusual style. The Trio/Kenwood L-07D (I will leave out the "Trio" for most of the following text as it was only sold under the „Trio“ brand in UK. The reason for this is to be found easily as the rights for using the brand name "Kenwood" belonged to another, UK-based, company then) looks totally different from all of the competing models by other manufacturers. Modern and stylish, but at the same time very ruggedly built, dealing in a most consequent way with the whole complex of resonance damping, it finds itself inducted into the imaginary "High End Audio Hall Of Fame".
The now infamous „07“ series of audio gear was developed at the Kenwood labs during the late Seventies. Trying to design and build the best audio equipment they could, beginning from scratch, it was a true „no compromise“ effort involving the best engineers the company had to offer. Competition was tough way back then and the age of digital media was already lurking around the corner. Nobody could have predicted the outcome of the “digital race” by then. So although it looked as if vinyl would face its armageddon once more a lot of energy, manpower, money and even more brainpower were invested in developing some ultimate machinery – especially for LP-playback. Trio/Kenwood simply called this department respectively project "07", this reasoning the use of the number in all the resulting products namings. The letter L as the prefix stood for "Laboratory (Series)" followed by „07“ and then the shortcuts T for Tuner, C for Control amplifier, M for Main amplifier and D for Direct-Drive-Turntable. Which is a far more logical product naming than the terminology resulting from many of todays “creative processes”...
Finally when the development process for the L 07D was finalized, there stood a statement turntable weighing in at 35,3 kg. The main unit alone has 31 kg, the external controlling unit brings along the rest. Both units are connected with a cable consisting of 20 leads and using JAE (Japan Aviation Electronics Industry Ltd.) connectors, usually found in airplanes. Anybody still wondering now about the sheer mass of the four height-adjustable brass footers (1,4 kg each)? I don’t think so. Even the vertically adjustable tonearmbase – allowing you to change the VTA during replay! – combines with the tonearm for 3 kg. Solidity wherever you look.
So right now we’re amidst the theme of
Let’s start with the main construction of the chassis, clearly developed as a complete unit and not – as seen all too often nowadays - by finding out that „... we’ve come up with a great, attractive appearance so this product can be sold – but which technical design shall we use?“ is the question left. Turntable-designs not planned as a whole do actually suck. Why don’t people learn from what, for example, the engineers at Kenwood learned 25 years ago? Some of these details do simply make sense: seperating the basic chassis from the motor bearing unit, making use of different materials with differing resonance demeanour, considering the importance of the relevance of traction unit and passive mechanical sampling kinematics etc. The result of incorporating all this was a pure mass device as opposing to the (then as today) well-respected Linn LP-12 as could be – technically as optically. Although it was for sure not in Kenwoods’ engineers mind to plainly realize the LP-12s antonym. They just followed a different principles and came to other conclusions. One main incentive was to keep the relative positions of turntable platter and tonearm as rigidly unchangeable as possible. This way, vibration- or otherwise induced displacements, being as short-lived or weak as they may come, should not stand a chance to have negative effects on disc replay. So the main construction inherits three pieces:
Firstly, the upper part of the chassis is the main framework made of a material called ARCB (Kenwood Anti-Resonance Compression Base), a synthetic concrete-resin compound. Aluminum framework is compression molded inside the ARCB plinth base and provides an ultra stable mounting base for motor bearing and tonearm. This main upper framework is connected through a total of 34 screws to a lower mahogany composite layer, which provides a third addition to the triple composite resonance-cancelling (ARCB – aluminum – mahogany) plinth. The motor unit itself is a brush-, slot- and coreless PLL regulated DC model made by TDK. The bearing holds a ball made of hardened steel – the same material the 12 mm thick center spindle is made of – running in oil on a teflon mirror. The bearing sleeve is a solid piece consisting of bronze. All moving parts are well lubricated with oil so a long life should be guaranteed. The very rigigly built Motor housing incorporates rotor, stator and a magnetic construction reducing the pressure applied to the bearing. Using a motor capaple of high torque, combined with the weight of the platter allows for the PLL not to be permanently active. It only takes active control if platter speed varies for more than +/- 3%.
Additionally there is a special external control circuit logic called "External Dynamic Phase Compensator" which helps to overcome factors like temperature, humidity or heat-induced changes in viscosity resistance of the oil in the bearing system within +/- 3% of the rated speed. If an outer stabilizer DS-20 and/or an inner stabilizer DS-21 are used, the Phase Compensator can be adjusted to that. Overall this is an elegant regulating concept allowing to avoid the need for a permanent control process which is often resulting in audible wow and flutter (“whining”). The braking problem was solved in an adequately elegant manner. First an electronic brake will slow down platter speed to 20% of nominal speed, then a mechanical felt brake will take over and stop the platter movement. This takes 2 seconds as a whole. The mechanical brake will then hold on to the platter until the "Operations" button is used to re-start the turntable.
The tonearm - correctly said: the tonearmtube - is made of a three-layer laminate consisting of aluminium, boron and carbon fibres. The critical connecting parts even sport six layers. The three materials are combined to form a J-shaped, stable, resonance-minimized, great-looking entity. Internal wiring is formed by a structure of five conductors each of which consists of 56 copper wires having 50 micrometres in diameter; the output chord consists of 168 wires with a diameter of 80 micrometers. Everything is optimized to minimize DC resistance. The add-on counterweight can be screwed onto the normal counterweight, so cartridges weighing from 10 up to 34 grams can be used with the arm whilst allowing for a tracking force of up to 2 pond. A basis for mounting a second tonearm and a second, semi-integrated tonearm with straight armtube were also available.
The headshell is designed to avoid critical resonances tending to occur with other headshells at frequencies from 1 to 5 kHz. To reach this goal, the fibres of boron and carbon forming it are laminated in opposing fiber directions.
The platter construction, like everything else on this turntable, was constructed to minimize resonances. The main platter consists of a three-layer structure: aluminium, duraluminium and again aluminium are the components involved. The “steel mat” on top of this is made of 4mm thick, non-magnetic steel. Combined, this adds up to a weight of 5,5 kg. It can be shored up by using the aforementioned DS-20 and DS-21 plus the TS-10 ceramic mat – which can be easily used by simply putting it on top of the steel mat, this being made possible by the unusually long center spindle. Result: more of 8,5 kg in total platter mass. Without taking notice of the rotors mass, that is. Looking at all the variations in weight made possible there was plenty of room to do some experimentation. Which obviously also took place in Kenwoods research department. History shows a lot of minor to bigger variations until Version II of the L-07D was finally marketed. Let me mention just a few of these: The „Control Unit“ was called "Power Unit" first, noticeable by its differing cover. Its internal layout was also changed several times. The headshell finger exists in two variants. The footers of the L-07D II were changed and got an internally adjustable damping. The stator inside the motor unit looks a lot different with the Mk II than in the original version of the L-07D (one of the most noticeable changes in my opinion – see for yourself in the pictures). Stabilizers DS-20 (outside) und DS-21 (inside, it too was named DS-20 in the beginning) were produced in two variants each, whereas the older versions were more lightweight than the newer ones. And so on…
Ist not always possible for me to understand the causes for some of these changes. Okay, some definitely had technical reasons – but some also may have been for the sake of cost-optimizing. Economical reasons came strongly into play around 1983, when digital replay was launched and Compact Discs began to spread worldwide. Remember that the L-07D was built from 1980 to 1984…
One of the obviously very few during its construction process more or less neglected facts that could cause some trouble is the absence of magnetic shielding of the strong motor unit. As it generates a rather strong magnetic field some impact on the installed pickup cannot completely be ruled out. Kenwood obviously trusted in the nonmagnetic steel mat to provide enough shielding – a trust I do not fully share. But with the device I had on hand it was no problem at all. Its owner already had solved the issue by installing a foil of MU-metal trimmed to fit underneath the steel mat. Therefore no magnetic leakage field would be capable of causing any disturbance. A good idea, so I didn’t have to worry about this.
On the mechanical side – except for the leverage used for fixation of the tonearm base - there is just one weak point in the whole construction to be found. I’m talking about the surroundings of the footers of the L-07D. These may break if the unit is not packed appropriately for shipment. So some Kenwoods for sure suffered the fate of damage and destruction because of hardly repairable serious harm. Too bad – because whoever invested 5.000 DM (pricing is from 1983) at the beginning of the Eighties had a serious interest in listening to musical reproduction. So if you shelled out that much money, just to get as close to musical perfection as possible, you wanted nothing less than perfection. Enough said. Now I’ve bleated when there is in fact no real reason for doing so. But if there is nothing important enough to critisize even small flaws appear bigger than they are. Most L-07Ds will not have traveled further than a few yards from where they initially were installed after the purchase. These yards may very likely be more like inches – while the room gets cleaned. The only thing to do as far as servicing is concerned is to check the oil in the bearing. Okay, after 25 years the Control Unit deserves a revision by a professional technician you trust. But this is nothing that has to be especially accentuated, it should be taken for granted.
By the way, you might be interested to hear that there was not only a – optional - record clamp deliverable (the aforementioned DS-21) but also an „Outer Disk Stabilizer“ named DS-20, which brought along ist own centering tool. Furthermore the DS-20 could be used to add some weight (more than 1kg) to the platter by not putting it on top of the record but attaching it to the platter itself. I’d have preferred this „mass-enhanced mode“, but unfortunately no DS-20 was on hand. Anyhow this great idea should not remain unmentioned.
How does the Kenwood behave acoustically? To answer this question I must say that most of my “audibles” were done by using Shelter cartridges (mainly models 7000 and 901). These matched beautifully with the L-07D. For a certain amount of time I teamed up the Kenwood with Denons DL-103R. This also proved to be a good combination. Mounting a cartridge into the seven-layer headshell (boron and carbon) was an easy task, soon the first LP was spinning on the ’table. I used a leather mat on top of the steel mat and the classic Michell clamp once again verified its worth, since neither DS-20 nor DS-21 were on hand.
Does it sound...? Not at all! And that’s good news.
It only took me a short amount of time to come to that conclusion. After a few days of exposition to the L-07D I knew it was right. My listening sessions went like this: I began with a sonically decayed recording like Fisher-Zs "Red Skies Over Paradise" (Liberty Records 1C 038 1575491). I’d love to listen to this record John Watts and his band made in 1981 more often (especially because of "Berlin", "Cruise Missiles" and "Marliese"), but if a turntable like the Kenwood shows you the full degree of disaster in sound originating from the complete audio engineering failure created here, I simply can’t. So I go on with the next record. Billy Bragg had a Re-Issue og "Back To Basics" done in 1993 on “Cooking Vinyl” (COOK 060, it inherits "Life's A Riot With Spy Vs Spy" originally released in 1983 plus "Brewing Up With Billy Bragg" from 1984). Two of his more well-known songs on this recording are "A New England" and "The Milkman Of Human Kindness". Musically as interesting as the Fisher-Z album, but enjoyably by far not as badly mixed (technically). My mood is getting remarkably better. Which makes room for Gordon Matthew Sumner aka. Sting and "The Dream Of The Blue Turtles" (A&M Records SP 3 750-1, 1985). Yes, thats the way it has to be. Atmosphere, even though combined with a little too much reverb ("If You Love Somebody Set Them Free"), jazzy influences (e.g. "We Work The Black Seam", "Love Is The Seventh Wave" or "Fortress Around Your Heart"), the ex-Police-mans characteristic voicing ("Russians") – everything seems right in place where it should be. If the "Moon Over Bourbon Street" begins to shine palely, goosebumps are the logical outcome. Its impossible to escape - too intense is the atmosphere of depressive mournfulness and desperation the singer creates.
Leaves us with the question of what happens when Rock or Classical Music are to be reproduced. What happens if the „food“ for the L-07D becomes more vigorous, more intense? Or if the depiction’s stability is especially in demand – likewise with piano concerts (solo)? To cut a long story short: There is no difference to the observations made before. No wow and flutter, the tone pitch remains intact. No smeared bass-presentation, no depressurized sound, no other acoustically frustrating phenomenons of any kind. But as the outcome is always the same I do not intend to bore you to tears. Therefore I will mention only two more musical examples. Classical Music and Rock combined – both styles do meet in an almost perfect match when finnish Metal meets “serious music” in Nightwish’s three-LP-box called "End Of An Era" (Nuclear Blast 27361 16791). It was the swansong of the bands lineup including Tarja Tuurunen. The final concert and highlight of a successful tour was not planned to be that final, but the band felt it was inevitable to part ways with Tarja right after the show. Until now her successor remains unknown – as do Tarjas future plans. That day at the Hartwell Ice Arena (it was November 21st in 2005, the record was published on June, 2nd the following year) is to be remembered as remarkable, to say the least. The record showcases Miss Tuurunens vocal capabilities (she is a trained classical singer) in a most intriguing way. Same goes for the powerful but refined melodic playing style of the band. Be it the insistent "Koulema Tekee Taiteilijan", the powerful rocking "Wish I Had An Angel" (both first published on the worldwide successful album "Once" (Nuclear Blast 27361 12911, released in 2004) or the magnificent "Sleeping Sun" (from the 1999 Maxi-Single "Sleeping Sun - 4 Ballads Of The Eclipse", Drakkar Records LC 00539) – the spirit of the music, the intensity of play, the interaction between musicians and audience was sheer magic. A combination of ingredients rarely to be found. All that was captured without adding artificial artefacts which could destroy the atmosphere. Plain wonderful. I almost forgot I listended to a record. In adversity to the behavings of some other turntables there is no audible influence from the L-07Ds side. It does obviously not have any “sound” or colorations. The record determinates what you get to hear, not the turntable. Unmistakably you can notice this behaviour while listening to Quilapayun on their record "Sandino" (Pläne 88339, 1983). The acoustical environment during recording sessions is displayed masterfully, depth and height are almost measurable. The position of each musician and instrument is perfectly marked and precisely outlined. Even up- and downwards movements are easily to follow, the voices sound realistic and not “enhanced” to be more than they are. So I can for sure pinpoint it as a true matter of fact that the Kenwood L-07D is far more than just a good looking gadget. It deserves more than being recognized for its looks. Most fascinating to me is its plain, straight, honest character in combination with its ease of handling. Something that is not all too common nowadays.
Summary: Although it differs completely from the first of the direct drive mega turntables - described in Hörerlebnis 57 -, the Denon DP-100M, there are astonishing similarities between these two - as well as in technical conception as realization of the basic ideas (You can find both predecessing parts of "Ohne Limits" in Hörerlebnis 57). Putting the fact, that both of these machines can polarize with their respective looks, aside, you will find that the Trio/Kenwood L-07D fulfills its assignment with the same low-key perfectionist attitude. It is a wonderful example of how much a "no compromise" turntable could distinguish itself from other concepts in its time. Just to finally end up with an unbelievable similarity in reproduction. Because all the real top end units do have in common that none of them shows any kind of own acoustic signature. As is with this machine. Had I not known the DP-100M or the Sony PS-X9 - both with an outline-background as studio workhorses - I could have sworn that a more stable, plain and contoured sound reproduction is unimaginable. And there are only two, maybe three „HiFi-designs“ I would consider comparably good. Which means: really good. “State-Of-The-Art” good. A place in my personal "Top Ten" of the best turntables ever is already reserved for the L-07D. And you won’t have to look down to place no. 10 to find the position where “the Kenwood” is located…
But who cares about my personal ranking? Nobody does – rightfully. If you take the time and opportunity to listen to a wide variety of equipment you know how subjective such a ranking is. So let’s get back to our subject. It is impossible for me to guess how big – or not – the effects of the modifications leading from the original L-07D to the final stages of the L-07D Mark II sonically really are. Anyway – one thing’s for sure: People owning an immaculately running unit won’t ask such questions. He or She incorporates a good, if possible even a great, cartridge into the analogue package, installs it in the headshell of the J-shaped 9” tonearm and listens to music. Let the High-End-Freaks out there discuss about the fundamental advantages of 12“ tonearms, harmonizing glue dots, plasticine damping or cable jackets. The proud owner of a L-07D likes to listen to records while knowing for sure that he or she has not the slightest reason to doubt “His/her machine”. The tonearm is in fact a lot better than most people think. And anyone feeling the desire to use another tonearm can do so by using the available, additionally mountable extra tonearmbase.
If you look at it closely it must have been a real pleasure to work in Trio/Kenwoods Research and Development department number 07. As it was the goal to push the envelope on sound reproduction there were only little, if any, compromises to be made. So the seven (hence the name!) best brains the company had to offer these days were indeed a great group. They did a lot of research especially when it came to resonances and how to optimally minimize/avoid them. The outcome is still, after 25 years, top of the line in terms of mechanics, sound recreation and build quality. Seen that way, this still futuristic looking device hailing from the past is living history. It shows us, where the future of sound reproduction could have headed from way back then - had other minds picked up at least some of the ideas incorporated in here. So we’re looking at some more wasted chances, at a somehow lost future never to be seen.
Nevertheless whining won’t help anybody, so let’s go right back to concentrate on the L-07D. I did not use it as intended by its creators because I hate to clamp vinyl directly onto metal. So I used a leather mat on top of the steel mat so the Michell clamp would press the LP onto the soft leather, not the hard steel. Call me a “softie” for that... It didn’t hurt the Kenwoods sonics nor did it worsen its fabulous looks. The sound? There is nothing to say about it – except: Extremely neutral, never adding any „colour“ or own characteristics, changes due to the cartridge used. A turntable for those really seeking the final statement in terms of record reproduction. If you can find one – numbers for production run rank between approximately 500 and up to 1.500 units...
Outro: I’d like to thank the helpful reader of ours who was so kind to lend me his L-07D for some time. Also thanks to Howard of www.l-07d.com, who is not only an expert when it comes to Kenwoods L-07D, but also allowed me to use some of his pictures.
By the way: The next turntable “to dream of” we will feature in this series will be the EMT 930st - a record player nobody from our crew could even come close to describing as well as our chief editor. Winfried Dunkel owns one of these “big boys” since many years and uses it regularly in his studio. Number "930" still plays a „leading role“ there - so that’s the title of his review…
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