WHAT'S THAT?
It's now well known that air leaks influence the bending capability. Due to reed position and other physical laws, it's very difficult (I would say impossible) to bend the lowest note of each acoustic chamber except if you make the opposite reed airtight.
So it's easy now to understand why you have only 10 valves on a 10 holes/20reeds harmonica. They are placed only on the highest notes of each hole in order to obstruct them when you make a bend on the lowest note.
Just an example: when you intend to bend the 4th hole blow reed your blow breath will stick the valve against the 4th draw slot.
As we also well know, Richter tuned diatonic's have the particularity to have the draw note as the highest in chambers 1 to 6 and the blow one as the highest in chambers 7 to 10. So valves will be placed against draw slots in holes 1 to 6 (i.e. inside the chambers over the lower reed plate) and against blow slots for holes 7 to 10 (i.e. outside the chambers and always over the upper reed plate)
How to achieve a bend with valved diato's
Exactly as you will do for an other bend.
Holes 1 to 6 allow you draw bend only (on an not valved harp). Valves will open to you access to blow bends for those holes (the opposite for holes 7 o 10).
But you must keep in mind that half step is only reachable by a bend on the natural note over the raise (#) you want to produce.
An example will help us to understand: Suppose you want to play country music in second position on a F harp i.e. in key of C. Very often you need a B in hole 5 draw. On a Richter tuned harp, 5draw is a Bb.
You can reach this B by a few means
Chromatic players will be certainly a little lost. They usually have the sharp (#) in the same hole by pushing the slide. With a valved diato you must move to the next hole, invert your airflow and then bend.
Usual bends are the result of a rear throat move and tongue shape. "Valved bends" are the same. I found it no more difficult to make "valved bends" than usual bends.
Lastly, don't forget that valved diato's make overblow/draw impossible.
About sound
Valves have an effect on the sound. Sound is louder due to airtightness. It's also more mellow. This can be heard when played acoustically, through an mic/amp set the difference with a not valved harp is very low.
What are the valved diato's on the market
I only know three models:
1) Suzuki
Pro-Master MR350 V
(be careful Pro-Master exists also with the part number MR350 not valved)
2) Höhner auto valved 580/20 (known in France as J-J Milteau)
3) And your usual diato valved by yourself.
3 is the cheapest, 2 is the most expensive. I personally play on 1.
In Fine
Many players consider valved diato's as a by-product in the diatonic range. Why? I don't really know. Harmonicas are a great family starting with the small 10 holes diato to the big all blow double bass or the wide 48 chord. Feel free to play what you want. For my own, I prefer to access some melodies I would not be able to play without "valved bends" .
Patrice MISTER LECLERC