Bracci eretici e errori immaginari

[alexis]

Sono ormai passati 80 dalle prime formulazioni degli errori di tracciamento (i famosi tre compañeros Baerwald Lofgreen e Stevenson)e del presunto allineamento ideale di una testina rispetto al centro di rotazione del disco, al fine di ridurli, che qualcuno decide di mettere a soqquadro questa leggenda, fatta di protractors, dine, microscopi, perle di sudore sulle fronti audiofile, manine tremolanti e cadaveri di cantilever sul tappeto. In soldoni qualcuno ha deciso per noi milioni di appassionati, che questo benedetto errore di tracciamento fosse l‘erba del diavolo.. aprendo poi le porte a un male molto maggiore, la forza di skating, un po‘ come voler curare l‘emicrania a colpi di martello per intenderci.

Ora non tutti sanno che la forza di skating è generata dall‘overhang/offset tra arco di cerchio del braccio e il coefficiente di attrito ( variabile.. ) tra solco e stilo, una formula di trigonometria abbastanza semplice ma sufficientemente complessa da lasciarla fuori da questa trattazione..

E come dicevamo forza discontinua, che nessun antiskating, a forza notoriamente costante, potrà mai curare o prevenire, se non con un balletto indecoroso di forze di spinta e trazione sul cantilever, dispositivo antiskating, per giunta applicato nel posto sbagliato.. ( approfondiremo dopo..)

Ecco come lo spiega efficacemente l‘ingegnere capo della Yamaha, potete rileggerlo in rete in capo alle numerose prove su strada del nuovo giradischi top della casa, il 5000, dotato di un braccino corto e orrore diritto come un ago..

Ecco quindi perché abbiano ( e qui ci metto noi come innocenti user pure la maggioranza dei progettisti) sempre sbagliato, in sintesi, castrando ab origine le prestazioni dei giradischi e dei loro bei bracci imperniati…  🥹

 

 

[alexis]

per i più tecnici, in calce alla pagina

https://www.blackforestaudio.de/cms/front_content.php?idcat=311

vi sono i disegnini questa é la teoria..

 

 

Regarding the tracking error he says: “A short straight arm has excellent tracking performance because the inside force is generated at the point of contact between a stylus tip and groove of vinyl and is always variable with the variate of the music groove. In the case of a short straight arm, its null point (= balanced point) is at the middle of the grooved area (so) the maximum tracking error is 10 degrees at innermost and outermost grooves. The distortion caused by this small error angle is inaudible because it is lower than both the tracing distortion and the residual noise. Furthermore, tracking error appears as phase shift between the left and right channels, and even at its maximum (10 degree) error the phase shift that results would be the same as caused by a difference in the distance from the left and right speakers to the listener of only 2mm. This also does not cause any problem for sound.”

As for the lack of anti-skating, he says: “A short straight arm does not require anti-skating because [at maximum error angle] if the vertical tracking force is 2g, the frictional coefficient is 0.3, and so the inside force (outside force) will be approx. 0.1g. In the case of a conventional offset arm with a maximum tracking error of 2 degrees, the inside force will be approx. 0.02g so the difference of the max inside force between a short arm and an offset type will be 0.08g at the maximum, thus the difference in force is very small.”

“On the other hand, when anti-skating is employed, because it applies a constant force it never cancels the inside force which constantly changes as its follows the music signal. The constant differences between the variable inside force at the stylus tip and the constant force by the anti-skating adversely affects the cantilever, hence the tracking performance is not stable. In a short straight arm the tracking performance following (the) music groove is excellent because the variable difference of force between the stylus tip and tonearm (cartridge) is not generated.”

[alexis]

◎Typical Product Feature of Rigid Float (RF) tonearm.                                           

"(1) Absolutely no mechanical contact at arm pivot bearing mechanism, resulting in highest sensitivity and maximum amount of howling margin (Which promises to reproduce rich but much tight base sound with no distortion, no muddiness, the most clear sound and wider dynamic range).
(2) There are similar type of bearing pivot, dipped in oil bath (Oil damp Type), available in the market, but still they require some string or another apparatus to fix fulcrum for arm rotary motion but RF, thanks to automatic positioning mechanism, requires absolutely nothing to interfere with the force, for cartridge stylus to follow the inward path of record groove.
(3) There might arise some lateral mechanical instability of arm with this type of bearing, but RF, equipped with the most appropriate balancing mechanism, assures the stability of the focus. This is the reason to be put the name of ""Rigid Float"".
(4) Pure Straight Structure (i.e. no offset angle) minimizes side force resulting the best channel separation, sound stage and sound atmosphere with highest transient rise time and no distortion even when tracing on the most internal part of vinyl record disc.(Detai follows below.)
(5) Beautifully anodized aluminum pipe is outfitted with the “resonance ring”, 3 pieces of synthetic ring rubber for damping. You may enjoy different sound in position of these rings in your choice.
(6) User friendly universal type head shell connector and for tone arm installation onto plinth, no drilling hole is required but just put it onto the plinth board.
(7) World uniquely shaped standard head shell “Nelson Hold” tightly supports the cartridge magnetic circuit, which is the most important part of a cartridge and at the center of which, stylus is located, on the other hand the conventional head shells hold the outsides of a cartridge body with 2 screws. “Rigid Float” with “Nelson Hold” removes haze and distortion from the sound completely.
(8) Inner wiring : Remarkable pure silver wire(4N) with silk jacket.
(9) Qualified RCA connectors with isolated ""earth"" terminal with possibility for balanced transmission line."       

               

◎ Stylus tracking force adjustment                        
                            
(1) Prepare separately available "Stylus cartridge tracking force meter" for tracking force adjustment.
 

◎ Side Force Superiority in Rigid Float tone arm                        
                            
"(1) Rigid Float (RF) with straight arm shape does not set any ""Overhang"" amount, but only reverse direction ""Underhang"", unlike many other conventional tone arm with offset angled “S” or “J” shaped products. 
(2) Conventional tone arms with proper overhang, create typical point where tangential line of cartridge stylus is in parallel with record groove line but still partial inside force towards tone arm pivot occurs somehow (Force in dotted line to arm pivot), resulting eventually still in inside force. (Fig-1 in ""RF Technical Description (B)"" )

 

(3) As (Fig-2 in ""RF Technical Description (B)"" ), straight tone arm would assure customers that absolute no inside force occurs at some certain point (Null position in straight arm) on record groove area by appropriate underhang adjustment.  



(4) Fig-3 in ""RF Technical Description (B)""  illustrates how inside force would occur in offset angle type tone arm system. 


  
Followings are representing figures:
     (θ) : Head Shell offset angle,  
     (α) : Tracking error angle, 
     (μ) : Friction coefficient between record groove and stylus,  
     (W) : Stylus Tracking (Force) weight,  
     (μｗ・tan(α+θ)) : Inside force 
     (μｗ・cos (α+θ)) : Pulling force towards arm pivot

(5) In Fig-3 at ""RF Technical Description (B)"", tangential line of cartridge stylus is in parallel with record groove line (α=0), under which occasion, stylus pressure to side wall of record groove is theoretically 90 degrees, being no tracking angle error.
(6) However there is still pulling force, arising from cartridge stylus to tone arm pivot in oblique with amount of  “μｗ・cos(θ)” and simultaneously, inside force amount of “μｗ・tan(θ)”, which means cartridge stylus is still pulled towards center of record disc spindle direction.
(7) Normally, as offset angle value of (θ) is around 25°, tan(θ) becomes 0.47, resulting in almost half value of total friction force is given to left channel record groove, reacting to cantilever base stem. even tracking angle error is zero point. ""
(8) On the other hand, in straight tone arm (Offset angle θ=0), inside force is only “μｗtan(α)” at any tracking erroneous angle area. if we set 10° as tracking error angle, tan(α=10°) is only 0.18 which is much smaller as inside force value than ones of  “S”, or “J” shaped tone arm with offset angle.
(9) In general, as (μ) varies a lot in accordance with music cut signal on record groove,  difference of inside force amount between “μｗ・tan(α+θ)” (Offset angled tone arm) and “μW tan(α)” (Straight arm) shows quite a few and, as it directly causes modulated sound distortion (As inadequate inside force causes to vibrate irregularly cantilever base stem where cartridge armature is located), reproduction sound of straight tone arm has much superior predominance against others.
(10) There is an Anti-Skate Device (Inside Force Canceller), available for offset angled tone arm which normally reduces certain constant value of inside force itself but is not in effect to reduce “Range of inside force deviation”, which means no way to solve this problem.
(11) In (Fig.2), null position of tracking error is set (By attached RF tone arm template, packed in product box for arm installment on turn table plinth surface) at just before the end of most inner record groove area where distortion gets the highest.
(12) Now, from stability point of view, tone arms, presumably a kind of bridge, sustained by cartridge stylus and pivot, the length between these 2 points is shorter the better but the thing is tracking error angle becomes vitally large when arm length is shortened.
(13) In straight tone arm, however, as offset angle (θ) is zero, shorter tone arm is now becomes available even by 7” length model which is almost impossible in “S” or “J” shaped tone arm, keeping much high motive stability and lower modulating distortion, developed by ViV Laboratory researcher and owner of Mr.Koichiro Akimoto. "        



 

[alexis]

Sembra latino, e forse lo é..  ma in soldoni una delle malattie dei bracci di lettura imperniati sta proprio nella adozione acritica dei postulati dei tre compañeros, e chi infatti è approdato ai tangenziali.. lo sa benissimo, pur sobbarcandosi una marea di problematiche aggiuntive..

ecco lo schema grafico.. su come si forma la forza di skating, figlia illegittima dell‘overhang…. Ove mü in greco indica la forza di attrito descritta come variabile e incostante, che nessun dispositivo che agisce nel fulcro del braccio, in un luogo quindi sbagliato.. tenendo conto anche del precarico dello smorzatore elastico potrà mai controbilanciare.  ☺️

[captainsensible]

Non sono un esperto di giradischi, ma il braccio a parallelogramma del Garrard zero non aveva risolto il problema ?

 

CS

 

 

[Roberto De Filippo]

. 

[alexis]

@captainsensible il braccio a parallelogramma garrard,  poi replicato in chiave high tech da Thales, da Reed e diversi altri risolve un problema, ma ne crea degli altri.. attriti meccanici degli snodi che si sommano. Già si sente un solo cuscinetto figurati dieci.. e poi la gestione delle vibrazioni spurie diventa difficilmente gestibile.

[alexis]

Certo ci sarebbero i tangenziali,  con errore zero e zero skating, che brillano per esempio proprio per la ampiezza dell‘immagine, a riprova che l‘antiskating è un problema tutt‘altro che trascurabile.. ma con un pesante prezzo da pagare in termini di complessità meccaniche.. e poi anche qui… visto con la lente.. cos‘è che porta a traslare il carrello del braccio, se non un carico asimmetrico sui due fronti del diamante…?