Preciosa 12 bass part 2

This stage covers the modifications to the bass action.

Preciosa bushed holes for bass buttons
Preciosa bushed holes for bass buttonsThe new bass plate fitted in place after marking out and drilling 12 holes on a rectangular grid.   The holes are reamed to about 10mm to accommodate an 8mm button and .9mm bushing of woven felt.  The holes are slightly conical getting larger towards the inside of the box to keep a good fit on the outside, but to allow some tolerance in alignment of the axis of the button with the axis of the hole. I borrowed this technique from concertina construction.

Next task is to reconfigure the mechanism to pair up bass and chord melodeon style (vertically) rather than stradella style.

Regina 1 Bass mechanism
Regina 1 Bass mechanism

This is the stradella mechanism, also showing the air button which is badly placed for melodeon playing, more of that later.

The pallets also need to be re-faced so I’ll do them while the mechanism is out of the way.

I’m hoping I can reuse the wire rods and just shift them to different positions.

Several of the button rods snapped when straightening the end to detach from the lever
Several of the button rods snapped when straightening the end to detach from the lever

So it will have to be new rods then.  The buttons are real mother of pearl so I’ll need to be careful to avoid damage when removing them.  Gentle heating with a gas flame softens the original adhesive which looks like shellac and they pull of easily.

Fortunately the rods are made of 1.5mm steel wire, exactly the same material as thin filler rod for gas welding which I have a stack of.  So its down to a couple of hours of careful bending and fitting to get the new rods made and installed.

Levers ready to accept pallets and rods
Levers ready to accept pallets and rods
First levers fitted
First levers fitted
All the new levers formed and fitted
All the new levers formed and fitted

Now its time for the reeds.

The reed work was fairly straightforward because the client has his own custom layout which is partly unisonoric and has no thirds in the chords. The D/G version of this layout is available here on unisonoric notes were able to use the original unisonoric accordion reeds as they were.  The chords each have three reeds either tonic+fifth+tonic, or fifth+tonic+fifth,   the choice being used to keep all the chord reeds within a compass of one octave.

Finally, I fitted a catch for the bellows lock to the bass block, replaced bellows gaskets and one or two other minor bits of tidying up and the job is done.

I found Clive’s unisonoric layout is very easy to adapt to after  only playing conventional melodeon basses.

Here is Clive’s response after receiving the converted instrument:

.. and here it is, all done, in action!

It’s a *fabulous* box to play; light, fast, great sound, and as flexible as my Mory (it’s got the same semi-unisonoric layout on the basses). It’s in Bb/Eb of course.

And these are the tunes that came out when it said hello: The Wrong Turn is a waltz/mazurka thingy written by Anne Marie Summers, English bagpiper, probably best known for her duo with Stephen Tyler on Hurdy Gurdy, and the trio Wendigo (with Julian Sutton). Played from *distant* memory, so it’s probably some way away from the original tune! The Sportsman’s is a traditional tune, and one I’ve known for ages, but only recently come back to playing after we’ve started using it in our Vivant stuff (slower than I play it here).

Thanks Theo!


I have another Hohner Regina 12 bass waiting to be united with a Preciosa if anyone wants one!

4 thoughts to “Preciosa 12 bass part 2”

  1. I’d be interested to hear how you did the air button Theo, as Mike and I pondered about that one quite a bit. We’ve ended up just enlarging the hole and fitting a slightly bigger pallet, which is adequate, but it would be interesting to see whether you’ve come up with a different solution.

  2. The original air button is in the wrong place, and the valve is too small, and the push in action is not ideal for a diatonic instrument.

    I just put in a complete new Hohner air valve in the usual melodeon position, and removed the old valve and blanked off the hole.

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