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alex_holden

Reed Chamber Length Experiment

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 (Robin, this was you who did this, right?) shortened the chamber of one of the highest reeds on the right side by filling the back end of the chamber with blu-tac

It was, Will, after conversations with Adrian.

Alex.....very neat  jig, well thought out both intellectually and in its simple construction.

               I don't think you said as much, but do you use this jig for tuning the low reeds ? They can be hard to tune due to the slow response on a tuning bellows and this jig would be easy enough to modify to obviate the problem would ?

Robin

        

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On 5/20/2018 at 11:13 AM, adrian brown said:

This is a very neat modification Dana, but what slightly puzzles me is that using this divider, the chamber volume is approximately halved, if we compare it to the chamber immediately above it in this photo, which seems to me to have the same size reed frame. Does this mean therefore that it's the length of the chamber, rather than the volume that is a determining factor in the response? How do the two reeds in question compare in tone and response?

Cheers,

Adrian

 

Good spot, Adrian. This would corroborate my findings that the length of air travel made more difference than the total size of the chamber in the ESB prototypes...

Okay, it seems like I will have a new hobby the next time I'm back in the UK where my test bellows live, Dana! Not quite as crazy as the guy who carried a piano up Ben Nevis, but definitely a bit out of the ordinary... It'll give me a good excuse to do some hill climbing 🙂

W

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On 5/20/2018 at 8:04 AM, alex_holden said:

I wonder whether reducing the size of the pad and hole might help with very high reeds, by moving the front edge of the hole further from the tip of the reed. Maybe even change the hole to a oval slot (across the end of the chamber, not along it).

I think the Dipper baritone I looked at had differently-sized pad holes, and I made measurements / notes about this, though I don't think I did experimentation about how this affects reed response... and I hadn't even considered the possibility of a differently-shaped hole (so the same amount of air can travel through it, while none of it gets too much of a "head start" towards the tip end of the reed). Nice insight, and I'd love to see whether that idea bears fruit. Another project for someday, if you don't experiment with it first... 🙂

W

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17 hours ago, Robin Harrison said:

               I don't think you said as much, but do you use this jig for tuning the low reeds ? They can be hard to tune due to the slow response on a tuning bellows and this jig would be easy enough to modify to obviate the problem would ?

Thanks Robin, I haven't done but it's a good idea. What I tend to do with sluggish low reeds on the tuning bellows is to pluck the tongue as I start to apply pressure.

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On 5/21/2018 at 6:28 PM, wayman said:

Good spot, Adrian. This would corroborate my findings that the length of air travel made more difference than the total size of the chamber in the ESB prototypes...

Okay, it seems like I will have a new hobby the next time I'm back in the UK where my test bellows live, Dana! Not quite as crazy as the guy who carried a piano up Ben Nevis, but definitely a bit out of the ordinary... It'll give me a good excuse to do some hill climbing 🙂

W

I think what my split chamber says is that high reeds like chambers that are as small as they will fit in.  Volume may not be the issue.  In my C/Gs, the same reed sits happily in a full width chamber the same length as the reed, but it is 1.5 mm shallower compared to the rh reed pan in the low G/D.  Chamber depth has an audible effect on tone.  I refined my chamber depths to get the tone I wanted.  This is one place where experiment is a very practical method to follow, rather than speculating on theory.

Dana

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