Stroboscopic disk sets wrong speed for turntable?

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.

lewm6,753 posts02-26-2019 7:12pmClearthink, 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