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Show HN: I made a free app to calibrate your turntable by simply playing a song

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Re: Show HN: I made a free app to calibrate your turntable by simply playing a song

#221

Post by ssl-3 »

Johnythree wrote: post #197
ssl-3 wrote: post #137

Earlier quoted context omitted.

Building a "strobe" is just a matter of putting an LED, some diodes, a resistor, and (optionally) a transformer together. The idea is that the LED reaches peak brightness (and darkness) at twice the line frequency, just as ye olde fluorescent tubes did. (Or: Skip the extra diodes and have it work at 1x line frequency. I'm not your boss.) After that, just print a strobe disc and use it.

Or even simpler, use a Neon bulb. or even a Fluro light.

Indeed.

But little neons are getting scarce (they aren't dear -- they're just much, much less common than they used to be). And working fluorescents (with magnetic ballasts that actually run at line frequency) are pretty much that way are too.

LEDs and resistors, though? Bright, cheaper than chips, and ready for all kinds of modern digital shenanigans.

Re: Show HN: I made a free app to calibrate your turntable by simply playing a song

#222

Post by criddell »

taylodl wrote: post #215
criddell wrote: post #127

Earlier quoted context omitted.

Do you happen to know of any tools for fixing pitch issues in music files?

Depends on what you're trying to do. For guitar practice, I use AnyTune Pro+. I use for learning the lead, because with my musical experience I can nail the rhythm guitar part by ear in a couple minutes. Not so with lead guitar parts, I'm afraid! But yeah, you can adjust frequency, you can adjust playback speed, you can pick a point A and a point B and loop between those points (great for breaking down each section o…

I wrote elsewhere that I recently asked Claude AI to help me learn a Pixies song on guitar and it wouldn't give me anything but generic advice because of copyright.

Re: Show HN: I made a free app to calibrate your turntable by simply playing a song

#223

Post by serial_dev »

BuildTheRobots wrote: post #143
nickthegreek wrote: post #25

Just put a record on yesterday and my wife said it was playing too fast. I thought she was wrong, then I see this post today! I grabbed the app and gave it a go, 3.5% too fast according to your app. Now I have to figure out how to adjust the damn thing. Really appreciate a free nonsense free app. update: youtube to the rescue. pretty common affordable turntable( Audio-Technica LP60), so I figure I would put the vid l…

I'd be curious to know _why_ your wife felt it was playing too fast. Was it out of tune, out of tempo or something else?

I believe with music it's much easier to notice that something is sped up. I'm watching videos, listening to podcasts all the time sped up, now don't even notice it, but with music, even a 10% speed up is extremely noticeable.

Re: Show HN: I made a free app to calibrate your turntable by simply playing a song

#225

Post by crazygringo »

jerf wrote: post #217
crazygringo wrote: post #120

Earlier quoted context omitted.

I don't think you could use FFT or similar to reliably measure wow to anywhere near the accuracy necessary to produce a reliable amount of correction from just a few seconds of an arbitrary LP. If you were using an LP with a known pure 440 hZ sine wave that you could lock onto exactly, then sure. That's kind of how frequency modulation -- FM radio -- works. But I really don't see how you could do this with songs that…

I am 100% abundantly positive that signal processing code could do this, and in fact by signal processing standards it's not even particularly hard. You may need more time than the app takes, though I am inclined to think that the app doesn't exactly need a number to twelve significant digits and you could get a single-digit-percentage significant digit lock pretty quickly. Even at 33&1/3rd you only need a few second…

> Now, scaling it down to where you can't hear it anymore may make it harder to believe, but the same code will pick it up.

That's where you're wrong. FFT frequency bands are surprisingly wide. You can make them narrower but with the tradeoff of losing temporal resolution. And it gets worse the lower the frequency gets.

There is absolutely no way you're going to detect a near-0.555 hZ effect from a few seconds of audio and determine whether it's off the frequency by 0.1% or even 1%.

Like I said, sure if you're dealing with a pure sine wave. But not a complex signal using FFT.

Or to put it another way -- a 1,000 hZ signal? Absolutely. But a 0.5 hZ signal? Absolutely not.

Re: Show HN: I made a free app to calibrate your turntable by simply playing a song

#226

Post by kazinator »

lightedman wrote: post #207
kazinator wrote: post #171

Earlier quoted context omitted.

Trial and error. Guitar meticulously tuned to concert pitch, with attention to the 12-15 fret area, then compare against versions of the track slowed down by all available factors in audacity from around 0.993 to 0.998. (The stretch tool doesn't take more digits, stupidly.)

"Guitar meticulously tuned to concert pitch, with attention to the 12-15 fret area" When you need to pay attention to anything outside of open string, fretted 12th, open harmonic 12th fret (and fretted 24th if you have a 24+ fret guitar) for intonation, it's time to get the guitar to a luthier for setup maintenance. Something else is drastically wrong in the setup.

When you're deciding between a 6, 7 and 8 cent pitch shift, using your instrument as a reference, you should pay attention to the notes you are using, no matter how confident you are in the intonation.

Re: Show HN: I made a free app to calibrate your turntable by simply playing a song

#227

Post by carb »

davidmurdoch wrote: post #219
okatbest wrote: post #164

Earlier quoted context omitted.

Here's the comment: https://news.ycombinator.com/item?id=40502383 Essentially I don't want to have somebody swoop in, replicate the same thing, be better at marketing, and charge money for it. I'm both protecting users because they shouldn't be charged for something that is free, but also protecting my ego because I spent time and effort and as far as I can tell I'm the first one to build an app that works this way a…

Usually when an app comes out on iPhone but not Android the excuse is that "Android users don't pay for apps so it wasn't a priority", despite it being way more difficult and a bit more expensive to develop for iPhone over Android. But in your case you don't plan on monetizing, so why iPhone first?

Mostly likely, they have an iPhone and this is for a need they had, so they developed it to solve their own need first.

I appreciate the fact that they're developing an Android version at all, because this sounds simple and useful for me!

Re: Show HN: I made a free app to calibrate your turntable by simply playing a song

#228

Post by okatbest »

davidmurdoch wrote: post #219
okatbest wrote: post #164

Earlier quoted context omitted.

Here's the comment: https://news.ycombinator.com/item?id=40502383 Essentially I don't want to have somebody swoop in, replicate the same thing, be better at marketing, and charge money for it. I'm both protecting users because they shouldn't be charged for something that is free, but also protecting my ego because I spent time and effort and as far as I can tell I'm the first one to build an app that works this way a…

Usually when an app comes out on iPhone but not Android the excuse is that "Android users don't pay for apps so it wasn't a priority", despite it being way more difficult and a bit more expensive to develop for iPhone over Android. But in your case you don't plan on monetizing, so why iPhone first?

Well I have been developing native apps for both for over a decade, and I don't think either is particularly more difficult than the other.

What it came down to is that I use an iPhone as my daily driver, and when I pulled my Android test device out of a drawer the battery was twice the size so I immediately brought it to an electronics recycling center.

Which means that in order to complete the Android version, I need to shell out $400 for a new phone I'm only gonna use once for a non-commercial project. So my idea was, let's release iOS first, see if people care, and then I'll spend the remaining time and money to finish up the Android build!

I think if I did try to finish Android at the same time, I would have given up on both and released nothing.

Re: Show HN: I made a free app to calibrate your turntable by simply playing a song

#229

Post by mlyle »

crazygringo wrote: post #225
jerf wrote: post #217

Earlier quoted context omitted.

I am 100% abundantly positive that signal processing code could do this, and in fact by signal processing standards it's not even particularly hard. You may need more time than the app takes, though I am inclined to think that the app doesn't exactly need a number to twelve significant digits and you could get a single-digit-percentage significant digit lock pretty quickly. Even at 33&1/3rd you only need a few second…

> Now, scaling it down to where you can't hear it anymore may make it harder to believe, but the same code will pick it up. That's where you're wrong. FFT frequency bands are surprisingly wide. You can make them narrower but with the tradeoff of losing temporal resolution. And it gets worse the lower the frequency gets. There is absolutely no way you're going to detect a near-0.555 hZ effect from a few seconds of aud…

I agree that FFT is not the easiest tool to use for the job. If I were trying to solve this problem, I'd use autocorrelation.

But it still sounds very challenging: there's multiple sources of periodic frequency change both in recordings and in playback mechanisms.

Re: Show HN: I made a free app to calibrate your turntable by simply playing a song

#230

Post by belthesar »

I'm not a turntable owner myself, so the app doesn't offer a lot of value to me. In thinking about it though, this app reminds me of the early days of mobile apps, where folks made neat, useful little tools to make life better. It wasn't about making a platform, or figuring out how to make a six figure sum, just a neat little ecosystem of fun and useful tools made by folks that had a problem to solve, and thought someone else might find it useful.

I see that it's free, but I feel like this could have easily been a $1 app.

Grats on making a really neat little focused tool!

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