2008 RMAF – – – all things analog.

Dear friends: Some additional thoughts/experiences on TT accuracy/speed stability.

I prefer the DD TT concept and Idler one but I like the BD too. This one IMHO is the more " delicate/critical " on set up to achieve its top performance.

Like many of you know or already posted here the speed accuracy and speed stability in the very short time are two of the main subjects and targets in any TT.

IMHO in any good executed TT design we can achieve those speed targets but in the BD TT type we have to take care more in deep on the set up, my experiences about told me ( in no importance order. ):

to mantain ( checking time to time ) in pristine/clean condition the motor(s) pulley along the " belt " ( any build/typematerial ) it self.

to mantain in pristine/clean condition the side/around platter where the " belt " spin ( try not to touch the side platter with our hands because we can/could leave different kind of " dust/residues " that migrate down the side platter and could interfere with the interaction between belt and platter )

to mantain and check ( time to time ) in/the perfect level both: the TT and the motor TT.

to be sure to stay right on the distance between the motor and turntable that the manufacturer recommend.

if there is a place where is important to have a electrical power supply conditioner/regulator IMHO our TT(s) must be connected through it.

check that the speed on the TT is precise: 33 1/3 rpm and 45rpm. Sometimes we buy a TT that right from the beguin has speed problems, so we have to be sure that at least it has speed accuracy ( other than speed stability ). I remember years ago that the Avid Acutus and one of the Rega TTs were reviewed and those units show inaccuracy on the speed it self ( not on speed stability ), this is more common that what we think about.

any " belt " of any kind and of different build material has its own " compliance/elasticity " value and like a cartridge compliance: it will perform right on target till settle down so we have to check about time to time, specially when we change it. How much time that " belt " mantain its top operation characteristics? I can't say it, we have to be " alert " about.

some " belts " change its characteristicis when the temperature change so we have to take care about.

Obviously as first step we have to follow all the manufacturer advise on the whole TT set-up subject.

Regards and enjoy the music.
Raul.

Dear Doug: +++++ " (stylus drag induced), " ++++

+++++ " accuracy and stability on held notes is a function of platter rotational speed. Nothing else in an audio system damages pitch like a platter that can’t maintain speed accuracy and stability. " +++++

I have to return to the subject because this is at least the thrid time that you post ( on other threads ) about stylus drag/speed stability issue and IMHO when someone is so repetitive on a subject could tell me that that is what he is experienced about in his audio system or that have facts that prove what is posting about or maybe the " whole problem " comes from other " source ", the analog sound reproduction is very very complex to understand every single parameter and its relationship between all them. I don't know either if in reality someone convince you about more that you heard it.

About the stylus drag that you states affect the platter speed stability I would like that you think for a moment on this:

a 20-30 kg platter that is spining at 33 rpm and where there is a " belt/motor " that it is trying to mantain that speed or a DD high torque motor doing the same.

then think in a stylus with a VTF of 1.5grs line contact shape and 12cu on cartridge compliance that is " running/tracking " through the LP and suddenly " find " a heavy transient where the stylus goes on because the stylus does not stop on the transient but follow a head.

then think that the stylus drag/friction on those tansient could be in any place on the recording: out the LP, in the middle, at inner groves or anywhere.
I point out this because if you try with your hand to stop a running ( onn ) Walker platter or a Tehnics Sp-10 you can see that it is more easy ( well not so easy at all ) trying to stop the platter if your hands are at the outer of the platter than at the inner side. The same for the stylus example.

try to think too on the complex process about because in my example the stylus shape is line contact: what about a eliptical one or other shape? what if instead of 1.5grs the VTF is 0.80grs? what about if the compliance is 30cu instead 12cu? what about if the tonearm type is dynamicaly balanced one instead static one? what about if the tonearm friction is 20grs or 10grs? what about...? what about... ?,, really complex fro say the least.

Now, do you think that that pitch/speed platter un-stabilities that you heard comes from the stylus drag ( between other things )? , could you thing that maybe comes from other " sources " that he stylus drag? can your common sense confirm about?

Unfortunately there is no ( or at least I can't find it ) measures about where tell us the whole true.

I don't want to disturb you I only want that something that for me is a " myth " ( like many others in this beautiful hooby ) till can/could be tested on a scientific/measure way does not be take it like an absolute true specially for the " newcomers/rockies " to this forum where the important people like you IMHO have a critical responsability to give the best " help " to those new people and cetainly to many of us that does not have the whole know-how.

I don't think, like you, that the ones that think ( like me ) that sometimes that wavering comes in the recording are totally wrong because not only for what I already posted somewhere and what I posted here but because exist errors in the recording process as there are errors that comes directly from the " players/musician ".

Regards and enjoy the music.
Raul.

I spoke with AJ Conti at length today regarding the stylus drag issue and it is basically BS.

I encourage any interested reader to contact AJ directly for the straight scoop from a person strongly educated in physics and mechanics not an amateur audiophile.

Dear Bill: Like always that you follow my posts and give some answer about: when I'm talking on " oranges " your non-sense answer is about " ocean/road " or what ever that does not have any relationship with the main subject.

This is what I posted:

+++++ " Regarding the stylus drag that Doug mentioned like one cause for the pitch anomaly is something controversial and TILL SOMEONE CAN/COULD PROVE/TEST/MEASURE IT IN SCIENTIFIC WAY IMHO is only a " mith " HERE I HAVE TO BELIEVE IN MEASURES MORE THAN " WORDS " , a measure than can tell me which kind/level of speed change ( if any ) can suffer a 20-30kg Walker platter ( example ) due to stylus drag ( VTF: 1.25grs. ) at 33 and 45rpm. " +++++

+++++ " try to think too on the complex process about because in my example the stylus shape is line contact: what about a eliptical one or other shape? what if instead of 1.5grs the VTF is 0.80grs? what about if the compliance is 30cu instead 12cu? what about if the tonearm type is dynamicaly balanced one instead static one? what about if the tonearm friction is 20grs or 10grs? what about...? what about... ?,, really complex fro say the least. " +++++

+++++ " Unfortunately there is no ( or at least I can't find it ) measures about where tell us the whole true. " +++++

I respect to AJ Conti as well any other people " amateur " or " pro " and with al respect to him and any one else if he does not have a scientific measure about I really don't care what he or you have to say in favor ot that " myth ", Bill facts/true measures not " words ", can/could you understand it?

The subject is extremely complex and maybe you can't understand it yet, so like almost always with you IMHO it is useless to continue argue with you.

Bill you are almost convince me that you are not the intelligent/wise person that I name it in the other thread!!!

Regards and enjoy the music.
Raul.

There is no question that stylus drag does cause speed variations. The only question is if the variations are large enough to be audible. Our ears are remarkably sensitive to extraordinarily small errors in the time domain. With digital audio it has been well documented that tens of pico-seconds of jitter is easily heard. That seems vastly too small to be heard, but yet it is. With analog it is no different. Very subtle changes anywhere in the drive system are easily heard. Different belts, pulleys and even component quality in the electronics all make a notable difference in the sound. If capacitor quality can be heard in a motor regulator circuit (and it can) then it's not much of a stretch to imagine that stylus drag would also be audible.

Regardless of the theory, what is indisputable is the fact that many techniques targeted to reduce the effects of stylus drag produce audible, positive results. Stylus drag may or may not be the culprit for audible degradations that we all hear but to me it seems like the most logical explanation. It is imprudent to categorically dismiss stylus drag without evidence.

Platter mass cannot reduce the effects of stylus drag. A massive platter makes speed variation shallower but also spreads it out over a longer period of time. So the speed variation is really of the same magnitude but has a different distribution.