Tuning a bandoneon?

[mChavez]

Hi all,

 

I've impulse-bought a 90-year-old bando(YOLO), and I'm overhauling the reeds right now.

My big question is: how does one tune a bando? Dry octave tuning - ok. File the reed to raise or lower pitch - ok.

But it's a two-voice bando and it's got shared soundholes - only one hole per pair of voices.

So when I put the reed plates into the box, I can't disable one of the voices to check the pitch of the other one🤪.

 

Thanks!

[malcolm clapp]

In short, mount and tune only one long plate set at a time.

 

(You probably should replace the flap valves prior to attempting to tune the reeds as I doubt the originals will be terribly effective after 90 years or so.)

 

Remove the plate not being tuned and replace it with a thin, rigid piece of ply/aluminium/whatever, cut to a similar shape to the removed plate. Tune the mounted plate of reeds, then remove it and repeat with the other plate.

 

Try this with just a couple of reeds first before tuning the entire set, and test the resulting pitch; you may find them it little sharp (or flat?) throughout, so you might need to adjust the targeted pitch a little below (or above) concert, assuming that is your intention.

 

There may well be a better way....but I've tuned a few instruments with long "gang-mounted" reeds using this method; total accuracy might be a bit elusive, so may need a little spot tuning "by ear" on completion.

 

I have also tried tuning by plucking the reeds rather than air blowing, but have found this less accurate, and a greater risk of breaking very old reeds.

 

Hope this helps. Good luck with the project  🙂

 

[mChavez]

Thank you. Good idea about the dummy plates! Never thought of it.

 

Yep, all leathers out. Could only get plastic to replace them for now, so might be a bit of a challenge picking the right valves for the basses.

2 broken reeds, and one more broke while I was cleaning. Will be an interesting job to replace them.

Edited August 26 by mChavez

[malcolm clapp]

Not knowing the exact range of your instrument makes it impossible to advise more than a guess for the cut off point for different types of valve (or not valved). And of course, it will be at a different physical position on each set of reeds with dry octave tuning.

 

Nothing wrong with mylar (plastic) valves for anything above middle C or thereabouts, and for the next 2 octaves. Anything higher than that, do not use valves on these as the benefit of air saving will usually be negated by the reeds being slower to respond. Depending upon how good the reeds are, you might find that even A and B and their near accidentals are a bit unresponsive, so maybe unvalve these as well.

 

Mylar may be problematic below middle C, so go with leather, and with helper springs on the larger valves.

 

If ordering leather valves, you will need accordion valves, not concertina valves for this type of instrument as the two have very different properties. Just saying, though you probably already knew that....

 

Have fun replacing the broken reeds; it can be a pig of a job. Just be careful you don't distort the body of the plate when tightening the rivets....

 

 

 

 

 

 

[mChavez]

Thank you.

What frequency do you mean by "middle C"?

 

Interestingly, originally, everything was valved, including the piccolo plates, and only 6 highest notes were without a valve.

[David Barnert]

54 minutes ago, mChavez said:

What frequency do you mean by "middle C"?

 

If you’re tuning to equal temperament and A is defined as 440hz, middle C (C4) is 261.6hz. If you’re using a different A, the ratio should be the same. If you’re tuning to a different temperament, you’ll have to look up a table of frequencies (or do some complicated math).

[malcolm clapp]

9 hours ago, mChavez said:

Interestingly, originally, everything was valved, including the piccolo plates, and only 6 highest notes were without a valve.

Go along with that then. But if the next notes down sound a bit weak, try them without valves.

The reason I mentioned it was that I have seen lots of accordions and concertinas where some one in the past has opened up the instrument and has seen reeds without valves; their automatic reaction was to think they had fallen off, so they slap valves on them and wonder why they can't get them to sound properly.

(No reflection implied on your experience or knowledge, but a common trap which some owners fall into when attempting their own repairs...  🙂  )

 

Edited August 27 by malcolm clapp

[mChavez]

Thanks. Yes, I am aware that usually the highest notes don't get valved. It can result in quite a break in timbre, because the valved notes sound noticeably smoother. 

I have, in fact, tried valving a CBA past the usual C6 with tiny plastic 1-layer valves, and it worked for about 5 notes before they became unresponsive. Smoothed out the transition a little bit, but overall was not worth the effort.

 

Here I've got the sexy straight & narrow bando reeds, rather than the accordion's tapered variety, so things might be different. I am very intrigued by some of the bandoneon solutions to making a squeezebox so far - individual axle keywork, leather buffers between pallets and key rods, joined reed chambers going through shared soundholes - everything is very different to the accordion.

[SteveS]

FWIW bandos used for Argentinian tango (Rheinische tonlage) I read that they are tuned to A=442Hz.

Edited August 28 by SteveS

[David Barnert]

On 8/26/2023 at 12:41 PM, mChavez said:

What frequency do you mean by "middle C"?

On 8/26/2023 at 1:40 PM, David Barnert said:

If you’re tuning to equal temperament and A is defined as 440hz, middle C (C4) is 261.6hz. If you’re using a different A, the ratio should be the same.

14 hours ago, SteveS said:

FWIW bandos used for Argentinian tango (Rheinische tonlage) I read that they are tuned to A=442Hz.

 

OK, so that would put middle C at 262.79hz.

[mChavez]

I don't get the fetish with tuning reeds to anything but A=440.

Why? Is it to compensate for potential reed pitch drift?

 

I think mine's around A=435 🤪. But since I need to true up all the tuning after re-valving, I might as well bring everything up to 440.

 

@ David - never heard of anyone ever using "middle C" as a reference. Usually it's A4. Learn something new each day!

[David Barnert]

2 hours ago, mChavez said:

@ David - never heard of anyone ever using "middle C" as a reference. Usually it's A4. Learn something new each day!

 

Me neither, and I wasn’t suggesting it. Just answering your question about the frequency of middle 😄

 

On 8/26/2023 at 12:41 PM, mChavez said:

What frequency do you mean by "middle C"?

[ttonon]

On 8/26/2023 at 10:04 PM, malcolm clapp said:

The reason I mentioned it was that I have seen lots of accordions and concertinas where some one in the past has opened up the instrument and has seen reeds without valves; their automatic reaction was to think they had fallen off, so they slap valves on them and wonder why they can't get them to sound properly.

If you're interested in a theoretical explanation of this, I believe it's because at those high frequencies, resonances of the chamber interfere with the self excitation mechanism that makes vibration of the reed tongue possible. The resonance can result from the cavity acting like a Helmholtz resonator or a quarter wave tube. 

 

You can read more detail at https://concertina.org/pica-volume-2-2005/reed-cavity-design-and-resonance/ 

 

Best regards,

Tom

www.bluesbox.biz

[Fanie]

I recently restored an old bandoneon which also had a broken reed. I sent pictures and measurements of the broken reed to Harry Geuns in Belgium and he sent me correct reed tongue. Contact him https://bandoneon-maker.com/

[mChavez]

Thank you - I've had some practice making reeds over the last few weekends and I'm highly confident I can make a good replacement.

 

I'm not really sure how your approach can work (quite curious actually!) - probably the hardest bit here is fitting the tongue to the slot, and it can't be done without having access to the reed plate. Riveting takes some skill as well, albeit nothing that practice can't fix. Making the tongue itself I found very easy and straightforward, as long as you have original reeds (same pitch or up/down a semitone) to use as reference point.