Stroboscopic disk sets wrong speed for turntable?


Hi all! I am new here.

I have just set up my Clearaudio concept turntable. Unfortunately, the speed of the turntable was wrong so I had to reset it. In order to do this I have used two methods: an iPhone app called RPM; the stroboscopic disk + the iPhone app StrobeLight.
The problem is that when everything is correct at 33 1/3 (both verified with the RPM app and the stroboscopic disk), the songs are playing one semitone lower than what they should. In order to make them play at the correct note, I have to set the speed at around 34 RMP as shown by the RPM app. Also the stroboscopic disk shows that now I am going faster than the 33 1/3, being consistent with the RMP app. How is this possible? Am I doing something wrong or even the stroboscopic disk is not accurate enough? Could it be the StrobeLight app not being an accurate enough light source for the stroboscopic disk? It is just peculiar that both the RMP app and the stroboscopic disk are consistent in saying that I am going too fast. 

Any help is much appreciated. Thanks!
agforte
Are you sure the app-strobe flashes at the right frequency for that TT?
Most iPhone apps are junk if you are dedicated, serious, and determined to obtain proper performance from your Music Reproduction System I suggest, recommend, and encourage you to purchase, borrow, or acquire proper, dedicated, precise tools to achieve correct setup, alignment, and calibration.

If your using a north American 60hz strobe disc just use an incandescent light bulb for your light source. if you have a 50hz disc then that could be your issue.

 That's all the lights are for built in speed control on record players that have that feature.

much more accurate then any phone app as well.

 Also are you using a set up record?

Hi all,

thank you for your answers. I am using a strobe disc that has both 50Hz and 60Hz markings. Since I am in the US I am using the 60Hz settings on the strobe light and on the disc.

I have also tested with a different iPhone app called Strobe Tachometer which seems more accurate than the other one I have used. However, it still tells me that the speed is a little too fast.
I do not have a set up record...I am assuming you mean a test record with a test sound. Correct?
There is nothing  better than the now defunct Phoenix Engineering Road Runner. It was hoped that Sota would re-introduce the product but it seems not at present. The design is not that complicated. A magnet and a sensor and a simple IC chip in a box to a read-out display. One would think there would be a ton of Chinese made cheap knock-offs but nope. 
Strobes are second-best but they almost always waver back and forth. Most platter engravings are slightly off. And then even if you set proper speed at one point in time, there is speed drift caused by motor warming, variations in voltage, and even stylus drag. The combined PE Road Runner and Eagle PSU was unbeatable, both for ultimate speed stability and value. But overall, the importance of exactly precise rotational speed is overstated imho. How else would Rega get away with fast tables for all these years? Mikey is fond of saying "precise speed is job 1 for any turntable". Rubbish. Lack of noise is number one-motor induced, bearing induced, stylus-record induced, et al. And even then, an argument can be made that the white noise associated with vinyl playback is largely why it sounds so good. It masks a lot of evils. I have a longstanding feud with Mikey (not that he gives it much notice other than an occasional solar flare) over this exact issue. Mikey expects ultimate vinyl playback to compete with digital for low noise floor and detail retrieval. I find that to be a waste of time, effort, and expense not to mention an impossible goal and a misdirected one. 
I would toggle the speed selector dial between all settings a couple of times, set back to 33.3 and see if that makes any difference. Maybe also lift the platter off and see if the belt is on correctly. Other than that I would suspect a motor issue.

fsonicsmith
"
There is nothing better than the now defunct Phoenix Engineering Road Runner"

The "Roadrunner" was as unreliable, poorly engineered, and flawed concept, design, and execution promoted by an unhappy, angry, vicious marketer who thought he knew everything there was to know about everything there is to know it is not a wonder, surprise, or mystery as to why his "business" folded abruptly, quickly, and without notice and that none of the other manufacturers he sought to continue its manufacture, production, and support were willing to affix their name to the product.
@bsmg I do not think this is a motor issue. The motor is working properly, it is just that if I want songs to be played in the right "note" or key, then the speed must read at around 34 RPM instead of 33 1/3.

I have tested with multiple LPs and with different songs of different bands. For example, at 33 1/3 Ticket To Ride by the Beatles plays in A flat instead of A. If I set the speed at around 34 then it correctly plays in A.
I just tested again with the stroboscopic disk (bought from Pro-ject) and just an incandescent lightbulb, so no iPhone apps! I still have the same issue, at 33 1/3 the songs are played not in the right key. I am really puzzled!
Clearthink, can you take a step back from the ledge and say why you so detest Phoenix? It’s a serious question, because the products are highly regarded by the vast majority. Thanks.
Strange......maybe it's just a rounding error on your measuring device since the other two speeds you have are 45 and 78....whole integers. Anyway, those were the only things I would have done myself (toggle the speed selector and set back to 33.3 and check the belt) After that, I would probably cuss and fuss.

lewm
6,753 posts
02-26-2019 7:12pm
Clearthink, can you take a step back from the ledge and say why you so detest Phoenix? It’s a serious question, because the products are highly regarded by the vast majority. Thanks.
Just click on his name and review his posts. He has started a grand total of 2 threads and the remainder of his 647 posts are little other than broad sweeping attacks that this or that brand is total junk. His recent "Conrad Johnson is cheap colored junk" post is classic. He's little more than a troll under a bridge. Don't feed him. "Clearthink"? How about "Delusionaldribble". 
I thought it would be interesting if by some chance he had something substantive to say about phoenix engineering. I do agree with you about the general tenor of his posts.In this case, I am still waiting. And I think we will all wait forever for a specific comment.
I keep forgetting to add one point I wanted to make with respect to the OP. Not only do I agree that the cell phone programs are notoriously inaccurate, but also so can a strobe be in accurate.  In many cases the 60 cycle frequency of the AC line is not stable. That can disrupt the frequency of any lamp that you plug into the wall. This is why I would recommend the KAB strobe. Which uses a battery operated strobe that is finely calibrated at 60 cycles. Plus the KAB device includes a disc that is wider in diameter than nearly any other I have seen.That also adds to its accuracy. And finally, it is not unusual to find that belt drive turntables without motor controllers can be slightly inaccurate as to speed. 
The Roadrunners Tachometers were an excellent product - and as stated earlier we have developed a replacement product for them.  Theres a few mechanical chassis parts left to be manufactured but the circuit etc is complete.  

It works "identical" to a Roadrunner by a tiny magnet tripping a hall effect sensor once per revolution. However it does not display "speed" rather a count which which is 33333 in exactly 1.8 seconds, 45000 in 1.33333 seconds and 78000 in 0.7692 seconds.  

The circuit is based upon 3 very accurate oscillators which output is divided by logic circuits and at each trip of the hall effect sensor the count is displayed on the 5 digit display.   Its highly accurate and will read actual "speed" at the  3 main speeds - there is however the caveat that any number lower than 33333 means that the table is running to FAST and any number higher means that its running too SLOW.  The same of course goes for the 2 other main speeds. Count to be displayed is selected by a switch on the back of the chassis which is slightly larger than the roadrunner. 

https://systems.audiogon.com/systems/4923#&gid=1&pid=15

We will be offering them for sale as soon as the remaining chassis parts are available.  Pricing will be $299

Good Listening

Peter
Thank you Peter! I thought it was PBN and not Sota that was coming to market with a similar product. Is it Sota that bought the rights to the Phoenix design but just for Sota tables?
Could you expound on why your product won't display actual speed? Is it so as to not infringe on the Phoenix design? Is the Phoenix design patented or otherwise protected from copying? Certainly the more intuitive the better and I don't see how anything could be more intuitive than displaying speed in rpm to two digits rather than what amounts to a revolution count without being per-minute. 
I presume you are counting on having perfect pitch to determine if the speed is correct. This is a wonderful gift!In any case, with  the strobe disc, be sure to use an incandescent lamp as mentioned before. As a cross check, use a test lp such as the The ultimate Analogue test LP from Analogue Productions and the hz function on your Fluke DVM. This is more precise than the strobe method and negates any presumption that stylus drag could cause a difference.
Wow you guys are good. Can you figure out my copy of Kind of Blue? Side 1 seems a little off....
https://forums.stevehoffman.tv/threads/miles-davis-kind-of-blue-mono-speed-issues.232772/
It is for the first 3 tunes where one of the tape machines ran slow. As the playback for mastering was on a different machine, these tunes are sharp on the early lps.
This was corrected later and is explained on the columbia legacy jazz cd that I have,
I read sometime last year that the regulatory agency for the utility companies relaxed the standard for 60 Hz, because it was too expensive and time consuming for the utilities.  So some type of device/app is now needed, that is not dependent on power company frequency.
bgpowell
I read sometime last year that the regulatory agency for the utility companies relaxed the standard for 60 Hz, because it was too expensive ...
I think your memory is failing you. First, there is no single regulatory agency for power distribution. Rather, regulation is left to individual states.

In the US, there are numerous distinct electric power distribution grids and they are managed by the non-profit NERC. It ensures reliability and sets the standards power suppliers must observe. Among them is power line frequency.

Power line frequency is tightly controlled within each regional grid. That is because each regional grid is supplied with power from multiple energy providers and all of that power must be properly synchronized (within tolerance) for the system to be reliable. The actual voltage provided by individual suppliers has a fairly wide tolerance - but not so the frequency.

The stability of the each regional grid hinges in large part on that tight synchronization of power, which is typically around ± .5 hZ. If imbalance between load and demand causes a substantial frequency deviation, automatic relays will shed load to preserve the frequency and the stability of the remainder of the system.

Of course, that may not be a tight enough spec for audiophiles using a synchronous motor on their turntables. For them, there are products such as the VPI SDS or ADS, and other products such as PS Audio’s regenerators.
I agree with Lewm that the battery powered KAB strobe would be the best way to go.
When I purchased his Walker motor controller for my Nottingham TT I first used a generic disc and a AC powered bulb to set speed.

Then a friend loaned me his KAB strobe and lo and behold it showed the AC setup was slightly slow.

Not cheap but highly recommended!
I saw a PBS tv show a few years ago about the nations electrical grid; they stated there are three of them: East, West, and Texas.
Sorry my memory was a bit faulty, it was a proposal by  the North American Reliability Corporation (NERC), an pro power industry organization.  There is a Federal Energy Regulatory Commission (FERC) which made Time Error Correction mandatory in 2009.  NERC put a second successful proposal to FERC, which is contingent upon the removal of the standard WEQ-006.  Anyway, not implemented yet but there is pressure.