Thats the info i was looking for without knowing it.
great help! thanks!

Yeah, that seems to be helping. Thank you.

@Walt: have you tried closing the blowreed slot? Does it get louder when you do that? The overblow should just get louder if you increase air pressure.

So I'm finally able to get an overblow, but the volume is really low. I'm trying to play gently, not force it, but I can't seem to get a similar volume as bent and an bent notes. Any ideas on what might be causing this?

thank you

No you can only overblow in holes where the blow reed is tuned lower than the drawreed, that would be hole 1 to 6 on a normal diatonic. In holes 7 to 10 you can't overblow, but you can overdraw

can you overblow in any hole

Very little needs to be done to the drawreed, although it does help the uniformity of tone if the reeds are set up similarly. Also gapping the drawreeds tightly makes it easier to get them to respond. But since this makes bending them more difficult you have to find the optimum gap yourself.

OK, Say you've done all the harp modifications to the blow reeds for overblows.
What modifications to the draw reeds need to be done, since that is the reed that
is really producing the overblown note. Help! Thanks

Thanks, T. The whole sustaining thing started to open up yesterday after listening again to your recordings of overblows on this site. Implementing the idea of seperate parts to the overblow is also valuable and very workable. Re-reading your info about relaxing the lips and cheeks was also helpful. I am getting the overblows to sustain with a whole lot less effort. Thanks very much.

If you loose control of the overblow then I suspect that you need to spend more time learning to control the seperate parts of the overblow. Open up a harmonica and isolate the reeds. first isolate the blowreed and learn to choke it really well. Try to choke the blowreed while playing really gently and then keeping it choked while increasing the pressure. Also work on just playing the drawreed. Isolate the drawreed and play the overblow note. Try to do this with as little force as possible. Especcially pay attention to starting the note softly, whithout extra force to get it to start, but starting it by resonance alone. If this works well start to bend the isolated overblown note up. If you can bend it up a fith or so you can start to play the overblows without isolating the reeds.

I am getting overblows on holed 4, 5, & 6. I have difficulty in sustaining the overblown note. Any advice on technique to do this? I have the reed gaps set very close. Thanks.