THORENS TD 309 - Ultra High-End Audio and Home Theater Review

THORENS TD 309 TRI-BALANCE TURNTABLEO N T E S THowever, this is just a personal observation—as with all mechanical systems, the proof isultimately in how well the feet perform theirintended function.The motor is supported in a cut-out inthe main part of the plinth first by a plastic‘insert’ that positions the motor off-centrein the cut-out and then by another ‘spider’suspension. (It probably won’t come as asurprise that Karl-Hienz Fink is a well-knownspeaker designer!) The reason for the off-centreplacement of the motor is sheer genius. Byrotating the plastic insert (after first releasinga locking screw) you can apply tensionto the belt, so that as the belt stretches withincreased use, you can compensate for theslightly looser fit by rotating the motor assemblyto restore the original tension. It’sso simple… and yet so clever. Once properlytensioned, the flat belt (it’s 4mm wide,496mm long and ground to a toleranceof 0.03 microns) maintains the same patharound the motor pulley and the aluminiumsub-platter assembly, so speed selection isnecessarily electronic. You can select between33.33rpm and 45 rpm, with an ‘off’ positionmidway between. The sub-platter sits on aninverted spindle-and-bearing for which thetolerances are ultra-tight—the engineering issuperb.The main platter, which sits on a raisedring at a diameter of 121mm on the aluminiumsubplatter, (this particular diameterselected by finite element analysis to be atthe lowest resonant point of the subplatter)is made from what looks like frosted glass(and in fact most reviewers say that it’s glassin their reviews), but according to Thorens,the platter is actually made from fused silica.Fused silica has a great number of highlydesirable properties, which include near-zerothermal expansion, low dielectric constant,low dielectric loss, that it can be lapped andpolished to fine finishes (as it is here) andthat it’s almost completely chemically inert.(Pedants might argue that fused silica is still aglass, because it’s technically a noncrystallineform of silicon dioxide (quartz, sand) andlong-range order in its atomic structure.) Toensure the main platter sits perfectly over thesubplatter, Thorens has formed a fairly largehole in the centre of the platter, then fitted asmaller black plastic internal sleeve to makethe link between the fused silica platter andthe central spindle. The tolerances on thistiny plastic moulding are also excellent. Theonly way I was able to ‘improve’ on the fitwas with a tiny ‘shim’ made from ultra-thinrice paper, but this ‘tweak’ proved ultimatelyfutile, since I couldn’t hear any discernabledifference in the sound with or without theshim.I had never seen the particular tonearmused on the TD309 before, which was abreath of fresh air. I am getting a little tiredof unpacking new turntables which aresupposedly fitted with ‘new’ or ‘proprietary’tonearms only to discover that the tonearmis actually just a slightly modified, re-badged,tonearm made by another manufacturer thatcan be found as standard fitment on a dozenother turntables. The Thorens TP 92 arm ISnew, and was designed by Fink Audio-Consulting.The tubular aluminium arm tubeis cold worked and rolled for strength, andthen its surface is coated with a materialthat damps resonances that would otherwiseappear in an identical, but undamped,tonearm. The arm allows you to adjust VTAand azimuth angle (rather fiddly to do, butat least you can do it!). Anti-skating adjustmentis accomplished magnetically, rather byeither a spring or a string-and-weight system.The arm’s high-precision bearings are madefor Thorens in Japan. The unique headshellmounts to the cartridge and arm tubeseparately, which makes cartridge mountingvery easy, but also allows 5mm of overhangadjustment. (If you want more, you can ekean additional 6mm of overhang from thebearing end of the tonearm.)Speaking of the tonearm, Thorens providesa large metal forging that looks like arecord spindle weight but isn’t: it’s intendedto balance the weight of the tonearm. Thisseemed odd to me, for several reasons. Firstly,the weight seemed heavier than the armcould possibly be, though I suspect one hasto take the moment into account (the tonearmmount being further away from the centralpoint than the weight) but also becausesince the turntable comes standard with theturntable, it would have made more sense (atleast to me) to have incorporated the extraweight into the plinth. However there’s achance that, while it does ‘balance out’ thetonearm, it also serves some other purposethat Thorens does not wish to reveal.I should make a note about the packagingused to ship the turntable, because I wasn’tentirely happy with it. The outer cardboardcarton is not particularly robust and inside,in line with European laws, there’s no polystyrene,so all ‘padding’ is provided by foldedsections of cardboard, and on my sample,the cardboard had shifted and dislodged theheadshell on the supplied phono cartridge.I am all for being green, but surely Thorenscould apply for exemptions to packaging lawsto allow it to use materials more suitable forprotecting such fragile components as phonocartridges, thin-wall aluminium tonearmsand fused silica platters?Listening SessionsEven though three feet describe a plane, sothat the TD 309 can never ‘rock’ on its feet ifthe surface on which it is placed is uneven,you still have to level the turntable if what-THORENS TD 309TRI-BALANCE TURNTABLEBrand: ThorensModel: TD 309Category: TurntableRRP: $2,499Warranty: Two YearsDistributor: Speakerbits Pty LtdAddress: Unit F51 63 Turner StreetPort Melbourne VIC 3207(03) 9647 7000(03) 9681 8207sales@speakerbits.comwww.speakerbits.com• Speed accuracy• Lack of rumble• Low wow andflutter• Dustcover• Feet levelling• Tonearmadjustmentsavhub.com.au25