Comment by kazinator | Hacker News Reader

Comment by kazinator | Hacker News Reader

I'm skeptical; you have no idea whether a random song from a record player is in tune or not, without a reference copy of that song from digital media.

Is this zeroing in on traces of 60 cycle hum in the recording?

Or else, won't it adjust an out-of-tune song to be in concert pitch? (Mind you, that would be extremely useful if you're playing along with the track and don't want to adjust your instrument, or cannot do so.)

To get it to the correct speed, I would go through my record collection and find a tune with long, sustained notes. Find the same tune on Youtube and get a pitch reference for the note using a digital tuner. Then adjust the record player to match the pitch on that note, down to 1/10 of a Hz precision.

(In the first place, why would you have a record player without a built-in strobe light for adjusting the speed in 2024, when this was a common item even in lower income households in 1984.)

Unfortunately a lot of mid-range tables nowadays don't have the strobe (mine included), most likely for aesthetic reasons... Even just looking at online shopping right now I only see a handful that do have it.

As for being skeptical, good! That means I'm doing something great according to Clarke's third law.

You can see me testing out the app on multiple records here: https://twitter.com/OKatBest/status/1795453042994680148

The results aren't 100% perfect, and they definitely won't be as good as matching specific frequencies, but it'll get you very close to the ideal RPM.

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.

60 cycle hum probably would not work, europe uses 50hz

That's a big enough discrepancy that the program could have heuristics to figure it out, particularly if the record player is in the right ballpark.

Also west Japan is 50, east 60.

The main problem is: (1) there isn't a lot of hum on professionally produced records; (2) but there may be hum from the equpiment itself.

Reply on news.ycombinator.com