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Bass reeds, lowest notes "aftervibe". Pffffbbltltltltltl sound (video included)

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On my International Centro-Matic-style SUPER accordion (3/4 LMMH), maybe 30 years old or so, the lowest bass notes persist making the noise described above after you release the button, which is obnoxious and odd-sounding. It's not metal-on-metal though, just the sound of the heavy weighted reed kind of playing on when button is released. I pulled the reed block and made a video of me blowing into the lowest C to demonstrate this. Its more obvious when playing the instrument I think, at least to me and some of the lowest notes are worse than others. It's the noise after I stop, you can see on the blowing one that it rattles the other reed and bounces the leather up and down a bit after stopping. I'm seeking to fix this. I have several thoughts on why this is and would appreciate any help in troubleshooting.
1)The leather valves and/or boosters may have been replaced at one time and the boosters or leathers aren't providing enough "closing" force to stop the heavy weighted reed's inertial movement. Do they look too small to you?
2)The reeds aren't stiff enough or are worn out and flimsy and just keep on vibrating.
3)The boosters need to be bigger. I've seen bigger or wider ones in the FRM enterprises catalog for instance.
4)A different style of leather might be called for here.
5)Resting height of the reed, clearance, is too great and it allows it to twang on longer?
6)This is just "a thing" and it can't be dealt with.

I'm leaning towards the leather valves and boosters being the culprit because if I finger over the leather when I stop blowing the sound goes away largely. Any chance this is just the quality of the reeds and thats what you get? They appear hand made as the rivets heads are rounded like they were hammered. What are your thoughts? Thanks.
 
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Dingo40

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I've been told by a very experienced (not to say "elderly ") dealer/repairer that this phenomenon is due to dodgy/elderly leather valves.
I experience it on the F bass (in the left hand) of one of my rather elderly accordions. However, with the music I play, I quite like the effect and it doesn't bother me.
In your video, you can plainly see the valve continuing to vibrate, not totally closing, after you have ceased blowing.🙂
It's one of the "faults " to look for when vetting used accordions.
 
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JIM D.

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May sound like a dumb question but but do the leather valves INSIDE THE REED BLOCK have boosters ???
From your video it looks like the the inner valve is not closing quick enough to stop the reed vibration.
It was a practice for a period of time that boosters were not installed on inner bass valves. Now I've worked
on many Lira Semi Pro & Pro models and always found they had in house exceptionally made Machine or
Hand made reeds. Not to say this is the problem in your case but when working on older Italian boxes I always
look for the lack of boosters on inner bass valves.
Another situation can cause this situation although rare is a gummed up and sluggish bass machine that causes
the bass pallet not to close rapidly. Again rare.
 
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So, remove the offending reeds, replace the two leather valves and boosters, then rewax them back in. Got it. Jeez, I might as well buy a set and do the whole rack if I'm going in this deep. Some of the other boosters are bent out of place and some leathers are visibly open at rest. Know a good online or phone-in source for these parts? I had called FRM enterprises in Maryland after reading their extensive online catalog, but they're a wholesale-only distributor. Is there a size/thickness of valve and booster that is supposed to vary with the size/weight of the reed? I'd like to replace with the correct one if I can. All of the boosters on this entire block seem the same size/thickness. Do big weighted reeds need bigger boosters? The leathers are smaller, thinner on the smaller reeds on the other side.

Jim, there are boosters on the inside reeds as well.

Thanks for the fast replies.
 

JIM D.

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Give Liberty Bellows a call, they now carry repair parts.

1 (267) 815 4407
 

debra

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There are two possible sounds (and possibly mixed): 1) the reed continues to vibrate a bit, and this is normal and is called "growl" and 2) the leathers may vibrate a bit which cannot be completely eliminated when the reed is still vibrating so even though the pallet is closed the reed is pumping causing the valve to not stay closed, whether the booster is working properly or not.
Growl is generally normal and as mainly a bass player I really like the growl of the lowest reeds, not only the sound but also the feeling of the vibrations going through your body.
 

JIM D.

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Yes FRM enterprises (Formally of Canada) is now located in Mass.
Frank Romano only sells to dealers and if you feel you need any of his products contact me in a PA as I
carry most of the items in his catalog.
 
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There are two possible sounds (and possibly mixed): 1) the reed continues to vibrate a bit, and this is normal and is called "growl" and 2) the leathers may vibrate a bit which cannot be completely eliminated when the reed is still vibrating so even though the pallet is closed the reed is pumping causing the valve to not stay closed, whether the booster is working properly or not.
Growl is generally normal and as mainly a bass player I really like the growl of the lowest reeds, not only the sound but also the feeling of the vibrations going through your body.
Growl. Thanks for the descriptor. How does one know that the size (length, width) of the booster is appropriate/sufficient for the size (weight) of the reed tongue and its expected residual vibration without being too much damping (closing) force when playing softly? There are many different widths and lengths of boosters for sale. All the boosters on both sides of this block are the same size, weighted reed or not. I don't have a mm caliper, but they are slightly less than 1/16th inch wide, so 1-1.5mm wide and ~42mm long covering a valve leather that is ~55mm long and 9.5mm wide. Thanks again for the lively and technical discussion.
 

debra

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...How does one know that the size (length, width) of the booster is appropriate/sufficient for the size (weight) of the reed tongue and its expected residual vibration without being too much damping (closing) force when playing softly? There are many different widths and lengths of boosters for sale. All the boosters on both sides of this block are the same size, weighted reed or not. I don't have a mm caliper, but they are slightly less than 1/16th inch wide, so 1-1.5mm wide and ~42mm long covering a valve leather that is ~55mm long and 9.5mm wide. Thanks again for the lively and technical discussion.
For the lowest octaves typically the size of leathers and the size of boosters you get is "the largest size available". Size also determines the strenght. The leathers need to be the distance from the (edge of the) nail to 1mm past the end of the hole for the reed long, and the width of the hole plus 2mm (1mm on each side). A longer leather can be cut to size. The booster springs need to run from the (edge of the) nail to 5mm before the end of the leather, so they are simply 5mm shorter than the leather. The strongest bosster springs are around 2mm wide. You fix the booster spring with a round piece of leather. The rule of thumb here is that it should have a diameter close to the width of the leather valve. I use 8mm leather pieces on the lowest bass valves. When the valve is really large, put two valves in a row for extra support of the booster spring. Below is an example showing how I found the leathers in an accordion that came in for repairs. The red dots are paper here (I would use leather). The image was to illustrate the source of a note that was out of tune at low volume, caused by the bulge in a leather. You can see here that the leathers and boosters have the size I mentioned.
P8202756.jpg
Here another picture how it was in an older Crucianelli:
P5311446.jpg
Here one dot was enough as the bass reeds are not that enormous. The boosters could have been just a little bit longer.
And here are the low bass reeds on a bayan:
P9292803.jpg
The very longest leathers sold (by Carini) come up a bit on the short side (so they do not cover the rivets at the bottom completely) and the longest and strongest boosters are also a bit on the short side for the lowest notes (on the right). But you get the idea...
 
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Good to hear that this "growl" on bass reeds is normal; I'm also hearing it on my 1980s Hohner Verdi, which I'm assured has been fully serviced. I don't hear it while I'm playing, but it's quite audible on the last bass note played when I stop playing. It doesn't seem to happen on the chords; just the bass note row.

Chris
 
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Well, all this info taken together would suggest that the boosters on there are 8mm too short, too thin, and the leathers are much thinner than the ones in the first pic that debra posted. New leather and booster job will probably make this growl lingering time much less and be more admirable rather than distracting and wrong-sounding. I have to finish my tuning bench setup before I do it all, but there's parts to acquire in the mean time as well.
 

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