New designs with longer, wider feet, such as Mollenhauer's Modern Alto, Adler's Bell Recorders and others, are increasing the available volume and evening it out over the entire pitch range, but we still lack in-tune dynamic range.

In April 1997's The Recorder Magazine, I read how a hole drilled out opposite the window raises the overall pitch of the instrument, and saw a patented design to operate a pin fitting into that hole with the chin. The recorder was played with the bell upwards for loud and held downwards, activating the lever, for soft.

That certainly sounded better to me than a finger operated device, but I felt that a better mechanism could be created by replacing the external lever assembly with a push-rod/valve through the block which would cover the tuning hole from the inside, and I decided to test this idea on my wooden alto. (If the worst came to the worst, quick epoxy wood filler could restore it to playable condition, right?...) It is activated by gently pressing the plunger against the lower lip, essentially the lower front teeth. Pressure is applied by the right thumb acting against the thumb rest. It worked admirably well, and I include construction details.

As shown in the diagram, the tuning hole is drilled through the bottom of the head, just in front of the block. A 3/16" hole proved a bit large, raising the pitch over 1/2 a semitone, but the valve travel can be adjusted so it doesn't open the hole all the way.
 

On the outside end, a spring operates between the head of the bolt and the outside of the block. This is the return mechanism to close the tuning hole at rest. A ball-point pen spring was about right. If the spring is too short, the lip-rest will hit the underside of the beak and jam. Compensate if necessary by screwing a nut all the way onto the bolt to shorten the spring space. If the spring is too strong, it makes for a stiff, tiring mechanism. Too weak and you press it unintended as you play.

On the inside end of the bolt, instead of a normal nut, goes a #6, threaded, round stand-off, 1/4" or more long (try an electronic components store, and pick up a bit of solder while you're there). The lower side of this piece covers the tuning hole. The options to make it fit against the tuning hole were (a) to drill a slot into the head joint with a drill the same diameter as the 'stand-off' valve, or (b), to file one side of the stand-off to the inner diameter of the head. Not having a drill press but equiped with several files, I naturally chose (b). This also became the height adjustment vis-a-vis the height of the hole through the block. If this 'valve' is too loose, air leakage will raise the closed-position pitch which necessitates pulling out the head joint a bit and reduces the difference between open and closed pitches. If it's too tight, the mechanism will jam. My final 'adjustment' consisted of stuffing a bit of exopy wood filler into the tuning hole with the mechanism in place to eliminate the slack.

I've since thought of a less finnicky design, shown below, but its tuning hole is not in the exact optimum position under the window, and there's some chance this could affect performance. (But I'll try it on my next recorder!)
 

The final touch is to attach the lip-rest to the end of the bolt.  I soldered on a (Canadian) penny, indeed an inexpensive part. A flat bit of cork covers this. If you don't solder, perhaps a large flat washer put on the bolt head with a nut would work about as well. But I didn't even use a soldering iron: after cleaning the face of the penny I set it on an electric stove burner and turned it on for one minute. (Just right for resin-core solder!) Then I melted solder onto the center and set the bolt onto it.
 

The recorder must be played oriented more horizontal than vertical, about 45 degrees or less. If you play with the bell pointing at your lap, you'll have to change your playing angle to use this tuner effectively.

Instead of dipping the bell as in the lever design, you just push the recorder a little farther into the mouth to activate the piston and play piano. I don't think the playing technique could be much simpler unless it could be made automatic. The travel is only about 3/16ths of an inch, so you're not 'swallowing' the recorder to play piano.

A thumb rest to push with is a must: it's an integral part of the tuning mechanism. It simplifies playing anyway; you should have one on any alto instrument. I already had clarinet thumb rests screwed onto my recorders. Taped-on thumb rests might eventually work loose.

You still can't really play piano up at high F'' and G'' as the notes won't sound (surprise, surprise). This is annoying when you're playing along piano and the next note has to be louder or it won't come out. Some of the innovative 'modern' designs are supposed to be better or have better alternate fingerings for these notes (and beyond).

It's also not as easy to play mezzo-piano where the tuner slide is (should be) half-way as to play either the 'standard' mezzo-forte (as I deem it) or piano, with the tuner at either end of its range, because it's hard to feel exactly where it is, and to keep it from moving. Players will likely find it most practical just to use 'out' or 'in'. Or, perhaps a shorter but stronger spring or some mid-way 'detente' could provide better feedback and ease of staying in the middle. But maybe anything besides 'loud' and 'soft' is drawing a pretty fine line on a recorder. It's certainly an improvement to have MF and P or PP for dynamic contrast, with some ability to play crescendos, decrescendos and in-between volumes reasonably in tune when they're really demanded.

It's not beautiful, and the 'valve' is a bit in the way when you swirl the cleaning stick through the head to get out the moisture (I told you I'm listing ALL the drawbacks!)

Another drawback will be having to consider and to play the indicated dynamics instead of ignoring them, and conductors remonstrating with you about same! "From he who is given more, more is expected."

The first playing test, playing through a piece marked with alternate forte and 'echoed' piano bars in succession, with one eye on the electronic tuner needle, was a breeze on the first try, though I was often a bit sharp in the piano(!) sections. The indicated crescendos and decrescendos worked reasonably well.

But there's more good news! Moving the recorder in and out rapidly produces a lovely vibrato-tremolo effect - a warbling of pitch similar to a violin's - equally on any note, or even in a moving passage. Is that available on any other wind instrument? It's quite easy to do except in fast passages and certainly is a fine addition to the repertoire of recorder tone colourations. It eliminates the tedium of steady held-note tones, which composers have usually had to compensate for by making them into trills.

I don't know just what this must look like to an audience, with the whole recorder moving in and out! An alternate design would be to reverse the operation: a thumb rest mechanism connection to activate the tuning hole and a stationary lip rest, leaving the recorder stationary. But this would be more complicated, and I suspect also harder to play - with the piston design, the thumb doesn't have to move with respect to the fingers since everything moves at once.

Finally: I have no plans for patenting this 'face-to-thumb-pressure-activated piston valve tuning device for recorder', so it's open season for recorder manufacturers, unless of course somebody I don't know of has done it previously and patented it. I hopefully look forward to seeing it become an option, or even a standard feature, on any new recorder!