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Wow & Flutter Phone App - How Reliable?

62caddy

62caddy

Trust but verify
Subscriber
I was recently introduced to a phone app that measures turntable wow & flutter. To do this, the phone is simply placed directly on a rotating platter and after several seconds it measures the speed down to 1/100th of an RPM along with percentage of W & F.

I find this app questionable since the balance of the platter will be seriously disturbed by the weight of the phone thus affecting results. Thoughts?
 
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I dont think the platter is disturbed that much by the phone.. I get the same result with the slipmat and a record on or off.
I tried the print out strobe disc but my speed was so far out (due to belt problem) i liked using the phone to see where i was at to the rectify problem.
Perhaps for the strobe disc is best for exact measurements from what i read.
 
Considering the great pains manufacturers take in machining platters for precision weight balance, the suggestion than several ounces of weight casually placed not having a dramatic effect is almost inconceivable.
 
I've tested a few tables with it on my phone and the better tables do indeed measure that way. Not sure if the results would stand up to a lot of scrutiny compared to using real measurement gear, but for comparing A to B with the same phone...it works.

jblnut
 
I said slipmat but I meant the heavy rubber mat. I would say that plus a record vs the phone is pretty close.
I guess this thread is about wow and flutter though which might require the rubber matt to measure properly.
 
For the normal user, the phone apps are fantastic IMO. What did we have before them except for strobe disks?

I don't have laboratory gear and I know few who do. I also don't necessarily trust test records to be flat and perfectly centered. We don't trust accelerometers in our phones but we trust the center hole in the test record is centered? Not sure about that.

The phone apps seem very useful for the average user to determine whether their table is fast or slow and (for some of the apps) to get a feel for W&F as well. What's not to like?
 
DavidTT said:
I also don't necessarily trust test records to be flat and perfectly centered. We don't trust accelerometers in our phones but we trust the center hole in the test record is centered? Not sure about that.
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Laboratory grade test discs are designed and made on an entirely different level of precision than ordinary records. They are usually thicker, heavier and much more expensive to manufacture.
 
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I've been meaning to do and share a comparison between the RPM app and a W&F track on a test record I picked up. My W&F numbers are a fair bit higher than spec for all of my tables using the app (and not audible to me), but I've read of others on here who had similar high numbers using the app, but better numbers using a test record and W&F meter (whether hardware or software based).

I don't have other phones around to compare the accuracy of the motion sensors. Would be a bit disappointing to learn if mine is inaccurate since it was a flagship phone a couple of years ago.
 
Taketheflame said:
I've been meaning to do and share a comparison between the RPM app and a W&F track on a test record I picked up. My W&F numbers are a fair bit higher than spec for all of my tables using the app (and not audible to me), but I've read of others on here who had similar high numbers using the app, but better numbers using a test record and W&F meter (whether hardware or software based).

I don't have other phones around to compare the accuracy of the motion sensors. Would be a bit disappointing to learn if mine is inaccurate since it was a flagship phone a couple of years ago.
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Same here - two identical models are testing 10x factory spec using the app. Neat toy but no substitute for laboratory testing methods.
 
Everyone disses the RPM Speed and Wow app, but whenever I have compared it to the strobe on my Technics SL-D2, they align almost exactly.The phone is a cheap Samsung.
I wonder if people are calibrating their phones' gyroscopes before using the app?
 
doctor fuse said:
Everyone disses the RPM Speed and Wow app, but whenever I have compared it to the strobe on my Technics SL-D2, they align almost exactly.The phone is a cheap Samsung.
I wonder if people are calibrating their phones' gyroscopes before using the app?
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Strobe markings are not reliable. The most accurate method is a laboratory grade test record with laboratory analyzing equipment.
 
The problem is: Set your speed with it and then move it .5” and the speed will be completely off + or -

W&F isn’t really W&F, it could possibly be speed stability over time, but once again move it and the readings will change.

Was curious about the app and checked it against my W&F tester, it’s not even close and the data changes (comparatively) with different machines e.g. DD vs Hysteresis

In my experience it functions differently with different motor speed control types, and if you construct a simple box to set it on made of different materials it will provide different results, (discover this by accident)

It’s great for general speed adjustment, but that’s about it in my experience….

VR
Andy
 
I don't have problems with the speed, it's not laboratory accurate 33.333333 but if I get a reading of 33.31 - 33.35 +/- 0.4, I can play a 10-minute symphony movement synced with digital and at the end they're nearly perfectly together which is certainly close enough for my needs. I don't take the data as absolute but it is useful to get things at 33.3 as close as I need. I don't find variance with slight position changes of the phone as long as it's reasonably centered. Wow and flutter is a completely different matter however...
 
Selmerdave said:
I don't have problems with the speed, it's not laboratory accurate 33.333333 but if I get a reading of 33.31 - 33.35 +/- 0.4, I can play a 10-minute symphony movement synced with digital and at the end they're nearly perfectly together which is certainly close enough for my needs. I don't take the data as absolute but it is useful to get things at 33.3 as close as I need. I don't find variance with slight position changes of the phone as long as it's reasonably centered. Wow and flutter is a completely different matter however...
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Understand and agree that listening to it is the key, and don’t doubt it works for you.

However my point is which 33.3 position is really 33.3, moving the phone just a bit will result is a slightly different speed as we know many people won’t notice a table that’s too fast until it’s fast enough to mess up a well known song, and even just a bit slow isn’t always noticed.

Again, that’s not to say one can’t get speed set to an acceptable point, it’s just that it’s probably not actually 33.3 unless their aural perception is extraordinary or their lucky ;)



VR
Andy
 
Not so much concerned with speed either - anything 33.3x is acceptable for me. It's the wow & flutter measurements I was mainly interested in. I tried again last night using the raised cup over the spindle with the phone centered as best as visually possible and w & f measurement dropped to half of what it had been with the phone off to one side.

Now a friend reported results very closely matching factory spec on a belt driven model having a platter weight of 7+ lbs. So it appears the lighter the platter, the greater the likelihood of error with the app; possibly direct driven as opposed to other drive types may also contribute to error as well.
 
62caddy said:
Not so much concerned with speed either - anything 33.3x is acceptable for me. It's the wow & flutter measurements I was mainly interested in. I tried again last night using the raised cup over the spindle with the phone centered as best as visually possible and w & f measurement dropped to half of what it had been with the phone off to one side.

Now a friend reported results very closely matching factory spec on a belt driven model having a platter weight of 7+ lbs. So it appears the lighter the platter, the greater the likelihood of error with the app; possibly direct driven as opposed to other drive types may also contribute to error as well.
Click to expand...
The difference you see though is the difference that imbalance makes on the performance, which is why platters are balanced. The effect is still there with the phone centered, just like if you had a perfectly centered dumbell on your platter, but less obvious. It's why the W+F numbers don't really mean anything. If anything it's a measurement of how well the drive handles imbalance.
 
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