Click title to read one, or click date to read all below it.
11-16-11
d & s, welcome to california ;-) -sam C1ferrari
11-16-11
thuchan wrote: voila ;-) vbr, sam C1ferrari
11-16-11
Very well put, learsfool. the importance of coherent rhythm ... Frogman
11-16-11
This is almost humorous, you folks are arguing about problem ... Davide256
11-16-11
isn't this "vibration at the micro level" a form o ... Hiho
11-17-11
Davide256, with all due respect, you are wrong. linn is ok ... Lewm
11-17-11
Hi thuchan, i do understand that your system stands in bav ... Unoear
11-17-11
the sota cosmos (couple models higher than your sapphire, w ... Hiho
11-17-11
Dear unoear, (why not duoear ?) you are fully correct. it ... Thuchan
11-17-11
Dear hiho, i am trying to understand your post on sota. do ... Lewm
11-17-11
That is one thing about the original empire table that they ... Atmasphere
11-17-11
Hi unoear - so the sirius is yours :^) i have never seen ... Ct0517
11-17-11
I didn't count the screws on the timeline thuchan because i ... Halcro
11-18-11
Never tried the timeline with the criterion because the air ... Thuchan
11-18-11
Dear all, i'm sorry i've stop watching the forum for a few d ... Geoch
11-18-11
Hi geoch, to my knowledge symphonic line produces amps not t ... Nandric
11-18-11
Dear nicola, this is the very first product by rolf gemein l ... Geoch
11-18-11
Dear geoch a pleasure to do so. again thank you so much for ... Ct0517
11-18-11
Thank you chris. of course a big yes by me, but i'll have to ... Geoch
11-18-11
Dear geoch, pls. give a warm hello to chris skaloumbakas. he ... Thuchan
11-18-11
Ok guys, now what about those overpriced dinosaurs full of g ... Geoch
11-19-11
"after living with it from '96 till today, i can say th ... Lewm
11-19-11
I would be glad to trade it for a goldfinger, a saec we800sx ... Geoch
11-19-11
Hi geoch, may i suggest the german sites : www.ebay.de and w ... Nandric
11-19-11
Thank you my friend. i appeciate your help, but at the momen ... Geoch
11-19-11
Hey geoch, nandric is right. you will definitely get a good ... Thuchan
11-19-11
Dear thuchan, thank you for your interest. a price of 5000 e ... Geoch
11-19-11
Dear thuchan, with all your gear (past and present) you of c ... Nandric
11-19-11
Certainly looks like a brinkmann but the bearing is quite di ... Geoch
11-19-11
the cosmos had the motor and platter mounted on the same su ... Hiho
11-19-11
excerpt from stereophile review of the sota cosmos: ... Hiho
11-19-11
Thanks, hiho. i am heartened that sota fixed that problem. ... Lewm
11-20-11: Tonywinsc
I have read this post with fascination and it has lead me to do some measurements and calculations. I am an engineer. This sort of thing is what I live for. I have an expensive belt drive tt and therefore I became very interested in determining if I need to invest $4k+ into a tt upgrade because I am missing out on some musical pleasure from my vinyl.
My first measurement was to pull out my strobe disc and fluorescent light. (Ugh I can hear some of you saying, but just listen a moment) I fixated on one black mark and in 10+ revolutions, that mark did not drift as best my eyes could tell. Next, I dropped the needle on the record while remaining fixated on that black mark. Again, no drift at all as best my eyes could tell. I must comment that considering the cost of most of our turntables these days, they sure better be able to hold speed with or without stylus drag. It would be a pretty poor turntable that could not. After all, this is the primary function of the tt- spin the platter.
So at this point, I'm pretty convinced that my tt holds rotational speed very accurately even considering the apparent disadvantage of being a belt drive. Next I put on my Stereo Test Record and played a 1000 Hz test tone. I can hear some Wow in the tone. The "A" tone, 440 Hz makes the Wow much more apparent. So where is the Wow coming from? The specs on my tt state a Wow and Flutter measurement below 0.03%. I believe it. That's part of what I paid for in this very expensive tt. I look at the record, and this is supposed to be a test record, and I see some serious runout. I can hear the Wow precisely when the tonearm is rocking outboard as the record is spinning. As with many records, the tonearm is swaying back and forth due to the runout- ie. the center hole is off position relative to the center point of the grooves. At this point, I would like to borrow a dial indicator from work to measure this runout. (I would also like to see just exactly how much runout is in my platter.) Since I cannot do that today, I measured the distance of the center hole of the record to the outer edge. I found the center hole of this record to be off center by 0.8mm or 0.0315 in. This would yield a runout measurement of 0.016 in. After searching the internet a while I found a specification for records that says the runout tolerance of the hole can be +/-0.015in. Allowing for some measurement error on my part, this test record has runout at the maximum industry tolerance. What does that mean from a sound standpoint?
Well, I measured the radius from the center of the record to the grooves with the "A"/440 Hz. That measured 3.5 in. This puts the groove velocity at that point at about 12.22in/s. Now factor in the runout of 0.016 in and the speed change is 0.05497 in/s. That causes a frequency shift of 2Hz. It is actually +/-2 Hz. This is the theoretical calculation. Now to measure the actual shift.
I happen to have a FFT analyzer handy. (Engineers, sheesh!) So I measured the frequency of the 440 Hz tone being played on my tt and coming out of the speakers. Guess what! I see the periodic Wow in the trace and I also see the frequency varying from 338 Hz to 442Hz! How about that?
I conclude that my tt maintains speed at least an order of magnitude better than a record with production tolerances. If the runout is 0.016in, then the Wow will be 0.45%. That is over 10 times the spec for my tt.
Okay, what does all this mean subjectively? I think that rhythm and pace is definitely a variable among turntables. I have heard it myself on different systems. I don't understand how it differs from one to another. Maybe no one does completely which explains the myriad of solutions in the marketplace for spinning a platter. Maybe someone could come up with a platter design that can true the record to the center of rotation.
Tonywinsc (System | Threads | Answers | This Thread)
11-20-11
A point was stumbled upon here, but no one followed through ... Mosin
11-20-11
Tonywinsc, interesting what you experienced during your test ... Thuchan
11-20-11
tonywinsc -- excellent post! i was thinking of the nak tx ... C1ferrari
11-21-11
thuchan, on my tt-101 there is zero speed change when the ca ... Halcro
11-21-11
Halcro, do you have an inbuilt realigning control unit whic ... Thuchan
11-21-11
Dear thuchan, the victor tt-101 is quartz controlled direct ... Halcro
11-21-11
mosin, as inertia is directly related to mass and friction.. ... Halcro
11-21-11
Henry - i want to see a youtube of the 3 cartridges lowered ... Ct0517
11-21-11
I found an article online about the nak. very interesting t ... Tonywinsc
11-21-11
Chris, your wish is my command :-) please forgive the amateu ... Halcro
11-21-11
Halcro, can you turn on the laser with the platter stopped a ... Tonywinsc
11-21-11
Perfekt henry! what is the name of the red lamp fixed in the ... Thuchan
11-21-11
While there is tremendous value in technical explanations fo ... Frogman
11-21-11
Halcro, another way to do it is with a stopwatch if you are ... Tonywinsc
11-21-11
Tonywinsc, your explanation makes a lot of sense to me....es ... Halcro
11-21-11
It will show that the designer used a motor with sufficient ... Tonywinsc
11-21-11
Keep in mind that the effect of the vinyl record runout is w ... Tonywinsc
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