RPM Speed & Wow app
newbie308
Posts: 767
I downloaded a couple of phone apps today to inspect the RPM of my Oracle Delph turntable. I was spoiled by my Technics SL1200 and it's built in strobe, and didn't want to wait for an aftermarket strobe and strobe disk to arrive, so I decided to check the Google play store. Sure enough, someone made an app for that. One uses your camera's LED light as a strobe. Don't bother with it. It's crap! The other one by Andrea Martignano works quite well!
Start the app, lay your phone on the platter of your turntable, press start on the app. It tells you to start your turntable spinning, delays for a few seconds for the platter speed to stabalize (or not...) and then samples the RPM for a period of time. It continuously displays the instant measurement, and when it is done the timed test, it displays the average RPM. All in all, not too shabby for a free app! Check it out!
Start the app, lay your phone on the platter of your turntable, press start on the app. It tells you to start your turntable spinning, delays for a few seconds for the platter speed to stabalize (or not...) and then samples the RPM for a period of time. It continuously displays the instant measurement, and when it is done the timed test, it displays the average RPM. All in all, not too shabby for a free app! Check it out!
Sources: Technics SL1200MKII | SME3009 Tonearm | Monster Alpha 1 MC cartridge | Oppo UDP203 disk player | Nikko NT-790 analog tuner | Musical Fidelity Trivista 21 DAC | Preamp: Threshold SL-10 | Amplifier: Threshold Stasis 2 | Speakers: Snell Acoustics C/V | Kimber 12-TC bi wire speakers | Analysis plus Oval 1 preamp to amp | Wireworld Eclipse 7 DAC to Preamp | Wireworld eclipse digital IC Oppo to DAC | Audioquest Quartz tuner to preamp |
Comments
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This is my go-to speed checker. KAB Electro Acoustics, 9V battery strobe. Numbers instead of lines makes it much easier to read. I like to check speed with needle in the groove. You just have to watch for when the stylus gets close to the speed checker disc.
https://www.kabusa.com/frameset.htm?/strobe.htm
Ken @SeleniumFalcon had posted this app ~ a year ago. RPM Speed & Wow by Andrea Martignano. It took a couple of tries to get the cell phone centered on spindle so it spins somewhat balanced.
The post...
https://forum.polkaudio.com/discussion/196120/a-wow-and-flutter-app
Salk SoundScape 8's * Audio Research Reference 3 * Bottlehead Eros Phono * Park's Audio Budgie SUT * Krell KSA-250 * Harmonic Technology Pro 9+ * Signature Series Sonore Music Server w/Deux PS * Roon * Gustard R26 DAC / Singxer SU-6 DDC * Heavy Plinth Lenco L75 Idler Drive * AA MG-1 Linear Air Bearing Arm * AT33PTG/II & Denon 103R * Richard Gray 600S * NHT B-12d subs * GIK Acoustic Treatments * Sennheiser HD650 * -
Thanks! I didn't realize that it was already mentioned in a post, and I didn't think to search for it.Sources: Technics SL1200MKII | SME3009 Tonearm | Monster Alpha 1 MC cartridge | Oppo UDP203 disk player | Nikko NT-790 analog tuner | Musical Fidelity Trivista 21 DAC | Preamp: Threshold SL-10 | Amplifier: Threshold Stasis 2 | Speakers: Snell Acoustics C/V | Kimber 12-TC bi wire speakers | Analysis plus Oval 1 preamp to amp | Wireworld Eclipse 7 DAC to Preamp | Wireworld eclipse digital IC Oppo to DAC | Audioquest Quartz tuner to preamp |
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No worries, it's good to remind everyone now and then!
Salk SoundScape 8's * Audio Research Reference 3 * Bottlehead Eros Phono * Park's Audio Budgie SUT * Krell KSA-250 * Harmonic Technology Pro 9+ * Signature Series Sonore Music Server w/Deux PS * Roon * Gustard R26 DAC / Singxer SU-6 DDC * Heavy Plinth Lenco L75 Idler Drive * AA MG-1 Linear Air Bearing Arm * AT33PTG/II & Denon 103R * Richard Gray 600S * NHT B-12d subs * GIK Acoustic Treatments * Sennheiser HD650 * -
Out of curiosity and strictly FWIW: How does one assess the accuracy and precision of that app on one's own phone? I think such apps for Apple phones are probably fairly dependable, since Apple's poducts are so monolithic. In the Android world, I think these are number generators unless demonstrated to be otherwise.
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To be honest I compared my tachometer with the phone app and the two didn't agree. Instead I timed my recording of The Minute Waltz and set the turntable speed using that. Sounds fine!
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You can always cross-check with The Flight of the Bumblebee. If it sounds like The Flight of the Cosmic Hippo -- something's not right.
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I'd be interested in knowing how those apps actually take measurements. I have two different ones on my 'Droid, but rarely use them.
I can't imagine it's truly GPS-based...the area is simply too small to be on 'the grid'. If it's measuring speed, it would depend from where inside the phone it is measuring. We all know that the inner part of a platter/record rotates slower than the outer edge, so where/how the phone is placed on the platter could potentially give different speed readings.
EDIT: I've also tried the strobe light app which uses the phone's LED. Using the app with my strobe disc, the 60Hz strobe setting didn't help me, but (I think) it was the 30Hz that actually allowed me to see the strobe disc markings better...not perfect, but usable. Of course any nearby lamp or ceiling light is usually sufficient for providing a 60Hz illumination...in North America
"This may not matter to you, but it does to me for various reasons, many of them illogical or irrational, but the vinyl hobby is not really logical or rational..." - member on Vinyl Engine
"Sometimes I do what I want to do. The rest of the time, I do what I have to." - Cicero, in Gladiator
Regarding collectibles: "It's not who gets it. It's who gets stuck with it." - Jimmy Fallon -
Accelerometers and vectors. The accelerometers measure velocity acceleration ( in the x, y, (and even, when applicable, z) directions and use those data to back calculate the rotational velocity. The physics textbooks usually ask students to do the opposite, but the equations work in either direction.
https://pressbooks.bccampus.ca/humanbiomechanics/chapter/5-2-angular-acceleration/
1 revolution = 360 degrees = 2 * pi rads.
EDIT: The accelerometer(s) in your phone are there for lots of reasons -- the most salient one I know of is to notice when you turn your phone from "portrait" to "landscape" and adjust the display accordingly.
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Androids have either an accelerometer or gyro. You have to research your android to find out. My S22+ is supposed to have both.
As I said, the KAB is my go-to. At my age I doubt I'd be able to follow the one with lines. I only tried the phone app after Ken brought it up so it's his fault.
Salk SoundScape 8's * Audio Research Reference 3 * Bottlehead Eros Phono * Park's Audio Budgie SUT * Krell KSA-250 * Harmonic Technology Pro 9+ * Signature Series Sonore Music Server w/Deux PS * Roon * Gustard R26 DAC / Singxer SU-6 DDC * Heavy Plinth Lenco L75 Idler Drive * AA MG-1 Linear Air Bearing Arm * AT33PTG/II & Denon 103R * Richard Gray 600S * NHT B-12d subs * GIK Acoustic Treatments * Sennheiser HD650 * -
Didn't know that!SCompRacer wrote: »Androids have either an accelerometer or gyro. You have to research your android to find out. My S22+ is supposed to have both...
