harmonica with covers on checking tuning 440?

Almost no harmonicas are actually tuned to A440, despite the stamping on the top covers of the original Marine Bands. Put an out-of-the-box harmonica on a tuner and you'll find that they're tuned as high as A445 or A446. And one harp will not be consistent.

Why? Three reasons.

1. Player's breath tends to depress pitch. A harp tuned to A440 may end up at 438 or something else even lower. I heard Chariie McCoy playing live with a harp tuned to A440 by a Hohner technician earllier that day (this was at a SPAH convention, where Hohner has a repair table at their vendor booth, and the tech told me about it) and he sounded flat to the band. Some players have their harps deliberately tuned as high as A446 tocomepnsate for their heavy pitch depression.
2. In some countries, A440 is no longer the de facto standard. In Germany it's mostly A444. You can always push pitch down on a harmonica to match the band, but you have no way to push it up.
3. To make chords sound better, some notes in the chord are tuned flat. By tuning the whole harp a bit sharp, the flat notes get closer to standard pitch.

I personally prefer A442. I tried 443, but it put me uncormfortable sharp when playing with A440 musicians. Many players seem to prefer A441, A442, or even A441.5.

I don't find a big difference with covers on or off, but it's easy enough to hold the covers on with fonger pressure while you check the tuning.

I wish it was so easy. The story is long because the truth is complicated.

Sorry about that.

If you're trying to determine the basis pitch for a harmonica, try this simple but laborious procedure:

Try setting your tuner to A440. Are all the notes sharp? If yes, set it to 441.

Are all (or most) of the notes sharp at 441? Raise it to 442. 

Are all (or most) ofthe notes sharp at 442? Raise it to 443 and try again.

Keep raising the tuner until most of the notes seem to be in tune. That will be the pitch basis for your harmonica.

Pay special attention to Blow 4 as this note is the basis for tuning the blow notes.

And pay attention to Draw 2, as this is the main basis for tuning the rest of the harmonica. Take special care not to pull the pitch of this note down when you test it.  

Also, be aware that Draw 2 is likely tuned 2 cents sharper than Blow 3, which is supposedly the same note.

All harmonicas are like this.

Even when companies make a statement about the pitch reference they use (a440, etc.) and the temperament they use (how much each note varies from equal temperament), actual harmonicas will be different.

You can document the differences.

Or you can simply play your harmonicas into tune - adjust the tuning downward as you play to put each note in tune with other instruments.

Or you can learn to tune your harmonicas so that they suit your preferences and playing style.

Or you can pay someone else to do it.

Some notes will be sharps or flats in the scale of the harmonica, but the tuner will detect these notes with no problem.

Some notes will be flat or sharp relative to the reference pitch, for two reasons:

1. Harmonicas are deliberately tempered - tuned to make the notes blend more smoothly (see my first reply for more information on why this is done).
2. The factory is making harmonicas very fast, and can't always be as accurate as we would like. The longer they spend, the more it costs. And harmonica players already complain about how much harmonicas cost.

Sorry, I didn't mean to give offense. The way you made your statement was open to the possibility that perhaps you were not aware that a tuner detects flats and sharps. Just in case, I covered that possibility to avoid misunderstanding.

I am trying to be thorough in my answers, and am sincerely trying to help.

Harmonica tuning is not a stupid joke. However, it is more complex than you seem willing to think about.

Tuning any instrument is part science and part art. And both are subject to the laws of physics and to human choices, which I've explained as briefly as possible.

Let me ask this question:

Are you expecting harmonicas to be tuned to equal temperament? Most are not because it makes chords sound bad. If you raise notes that are flat to equal temperament, you will achieve that effect. Avoiding those sounds is one reason that a variety of temperaments have existed for many centuries; they didn't start with the harmonica.

I would suggest that you play chords and two-note intervals on a harmonica and listen carefully to the effect produced. Also listen carefull to the tuning of Blow 4, Draw 4, Draw 2 and Draw 6. Then check the tuning against the tuner. And play the harmonica with a backing track that you know to be in standard tuning. Record it and listen back. How does the tuning sound? This will be your guide to making any adjustments you feel are necessary.

I might also suggest some reading on the subject, if you have the patience:

http://patmissin.com/tunings/tunings.html