Valve noise

[ttonon]

3 hours ago, Dana Johnson said:

In my experience, reeds that are set low enough to risk choking under either rapid pressure gradients or high pressure...

Interesting because I'd predict the opposite.  My guess is that setting the reeds to low offset would increase their tendency to choke under large pressure amplitudes imposed at the opening of the key.  Aren't large offsets the way to accommodate such high driving pressures?

[Chris Ghent]

I think you have misread Dana, Tom.  You are in agreement. 
 

Tom, your man with the bandoneon; my guess is he doesn’t know much about his instrument but knows he can get what he wants out of it, so he imagines it must be right. 

[ttonon]

On 3/12/2021 at 7:49 AM, Chris Ghent said:

Tom, your man with the bandoneon; my guess is he doesn’t know much about his instrument but knows he can get what he wants out of it, so he imagines it must be right. 

Hi Chris, I think you're right.  I went to the site of a bandoneon restorer at https://www.alma-bandoneon.de/en/ and asked him the question. His response is below.  Sorry for getting us all off on a crazy tangent of mine.  It seems bandoneon makers have some unique ways to treat the leather valves.  On the effect of tongue offset, what he says checks with the practices in accordions and concertinas.

 

Hi Tom,

thank you very much for your interest in my work. 

 

Your question relates to a topic in restoration where musicians and restorers split into two camps and which is much discussed.

 

Technically, you have to keep in mind that at the time the bandoneons were made, leather was the only suitable material .The leather was relatively thin and very flexible, so that it could give way quickly when the reed swung and just as quickly folded back when playing in the other direction or the reed came to rest. 

However, over the years, leather will dry out and curl up towards the skin side (which is what you observed). 

Attempts have often been made to prevent or remedy this by making slight cuts in the surface of the leather. 

It is normal for the lamellas to stick out slightly from the reedplate, but rolled up lamellas cause unpleasant background noises and detuning. 

In addition, they also lead to a deterioration in the sound response and higher air consumption. 

 

When you look inside a bandoneon, you can only see the leather lamellas, which are opposite the reeds that you play in opening direction. 

In tango, the bandoneon is mainly played pulling, so that these leathers bend outwards more often. The lamellas inside are mostly much more flat ; )

 

Modern lamellas are usually made from a combination of leather and a thin plastic sheet. The leather lies on the reed plate and ensures a warmer tone and the foil bends the leather back into its position. 

Valves made of full plastic, as often used in the accordion, are not very popular with the bandoneon. They amplify the upper sound frequencies and the sound is "falsified“. 

 

Choke of the reeds in severe staccato has a different cause and depends on how the reeds are bent (adjusted) towards the reed plates. The rule here is that the less the tongues are bent, the easier it is for them to respond. However, this also means that they no longer work at high air pressure. Conversely, tongues that are bent up very far still respond well at high pressure, but consume more air and are insensitive.

 

Lot of the old school bandoneon players are very conservative and swear on the original, 90-110 years old leathers, even if they are not perfect any more.

 

Whether new or old lamellas is a matter of taste. However, rolled up valves prevent the instrument from functioning properly.

 

The perfect adjustment of the reeds, voicing and choose of the right leather lamellas and tuning is the most difficult part in my job. 

 

Kind regards,

Christoph