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PostPosted: Sat Nov 04, 2017 12:11 pm 
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Koa
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Location: Durango CO
First name: Dave
Last Name: Farmer
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I've had an early Peterson VS-1 on my bench for over a decade and pretty much hated it the whole time. Having recently been worked over by my phone carrier, I now have a !@#$!@#$ smartphone. I splurged and spent $10 bucks on Peterson's mobile ap. What a huge leap in screen clarity!

Only one question.
why does it sometimes read 5 cents flat compared to my VS-1 and old Korg ?
Can anyone explain it to me or have a theory? (yes they're' both set to 440)
Something to do with averaging the harmonics for the displayed pitch?


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PostPosted: Sat Nov 04, 2017 7:32 pm 
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Koa
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First name: Trevor
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Straight answer - no idea!

Here's some possibilities: Most tuners "fire" on the largest amplitude partial, which is not a bad idea because that seems to be what our brains fire on, too. The largest amplitude partial is quite often the second, because we tend to pluck at 1/4 string length and so it gets excited more than the fundamental. 5 cents sharp on the second partial due to normal string inharmonicity would not be out of the question.

So: a) as the sound decays, the fundamental can decay slower than the second partial and the tuner will switch to trigger on the fundamental, which is why you'll occasionally see a tuner "jump" or be unstable on a single note.
b) Depending on the frequency response of the mic, one tuner might be firing on the fundamental, the other on the second partial, depending on which one is seen as the highest amplitude to that mic.
c) "Smart" tuners have enough processing power to pick the lowest frequency partial present, and will fire on that. It won't necessarily sound more in tune, though.

If you have a tuning fork, all tuners should read it the same, as there are no partials to fire on. If you pluck over the 12th fret (open string) you can be pretty certain that the fundamental will be the highest amplitude partial, and most tuners I've come across seem to be able to trigger on it correctly.

Apps like the old G-Tune show a spectrogram and indicate which partial is being used as the trigger. You can force it to trigger on a particular partial, if you want. Apps like AP Tuner will plot the frequency variation of each partial over time (which is of interest to piano tuners). So depending how fast a tuner triggers and how well it tracks, you may get a different answer. iirc, the human brain takes about 0.2 seconds to assign pitch, so ideally you'd want a tuner to match that.

More, I suspect, than you ever wanted to know about tuners....

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Trevor Gore, Luthier. Australian hand made acoustic guitars, classical guitars; custom guitar design and build; guitar design instruction.

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These users thanked the author Trevor Gore for the post (total 3): SteveSmith (Sat Nov 11, 2017 7:04 pm) • Michaeldc (Sat Nov 04, 2017 9:51 pm) • david farmer (Sat Nov 04, 2017 8:52 pm)
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PostPosted: Sat Nov 04, 2017 7:37 pm 
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Brazilian Rosewood
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Cool! I guess that's why the Snarks will jump around a bit.


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PostPosted: Sat Nov 04, 2017 9:09 pm 
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Koa
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Location: Durango CO
First name: Dave
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Thanks Trevor,
I'll mess with plucking locations and tuning forks out of curiosity.
I figured it had to do with what the different tuners were,"listening to" but I'm surprised the difference is so large. Especially between products from the same company. It seems like extream "accuracy" is a bit defeated if everyone pulls out their own tuner and and tunes perfectly to different things.


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PostPosted: Sat Nov 04, 2017 9:44 pm 
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Cocobolo
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I noticed the same problem with the phone app, but when I tried the app using the clip on accessory "mic" it worked great. I wondered if the mic on the phone was "tuned" or equalized for close proximity voice and that somehow skewed the results for more distant guitar notes. Though this is much less informed hypothesis than Trevor's post.

Kent



These users thanked the author kjaffrey for the post: david farmer (Sat Nov 04, 2017 10:21 pm)
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PostPosted: Sat Nov 04, 2017 10:34 pm 
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Koa
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david farmer wrote:
Having recently been worked over by my phone carrier, I now have a !@#$!@#$ smartphone. I splurged and spent $10 bucks on Peterson's mobile ap.


Hey you kids! Get off my lawn!!!!

Welcome to the world of technology, Dave. Before you know it you’ll be on Instagram showing us pics of all the cool stuff your working on. My son calls it “The gram, bruh”. So there, now you can sound cool in front of your kids.

Since Trevor wrote pretty much the same thing I was going to write, I’ll just leave it at that. :D

Brad



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These users thanked the author bcombs510 for the post: david farmer (Sun Nov 05, 2017 11:01 am)
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PostPosted: Sun Nov 05, 2017 11:00 am 
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Koa
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Location: Durango CO
First name: Dave
Last Name: Farmer
City: Durango
State: CO
bcombs510 wrote:
Hey you kids! Get off my lawn!!!!


laughing6-hehe laughing6-hehe

Reminds me of Don's excellent (as usual) post in the "How much do you charge for your guitars" thread. My old flip phone, had a large pile of customer Numbers's in it and received a lot of butt dials. "morons". I'm suddenly more sympathetic. So far, (I think :? ) I've only called one customer at 4am fumbling with my phone in the dark. "hows that Strat playing!?" :mrgreen:

And now I have to worry I've screwed up the intonation on every instrument for the last decade. :)


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