Excelsior Accordion Feature

[boxplayer4000]

An Excelsior, like the one in the picture, needed some attention (couplers) and I noted the unusual feature, circled in white, on the way along. This is a small, spring-loaded T-bar device hinged at the end where it fits to the accordion case and the top edge of the ’T’ rotates. A coil spring on the vertical leg of the ’T’ keeps the bar pressed against the reed blocks.
The reed blocks are secured in a fairly normal fashion with ‘standard’ sliding clips at the ‘high’ end. On first site the T-bar looks like it might be there to assist in keeping the blocks in position and secure but the coil spring is not very strong and as far as I can see adds little or nothing in a ‘securing’ sense. Is it reasonable to suppose that the T-bar’s function is to mechanically connect the (resonating) reed blocks to the outer shell of the accordion and thereby improve the sound?

 

[JerryPH]

No, but it does help keep the reed block properly aligned and avoid it shifting resulting in loosing air and/or notes.

 

[tcabot]

thereby improve the sound?

The accordion plywood box is pretty much acoustically dead and I severely doubt it's ability to produce sound.
On its own, in perfect silence it's amplifying effect might just about be audible if you try driving it by putting a reed against it and pinging it with your nail, but when sounding against a powerful air-driven reed, any sound from the box itself will be masked and your ears won't pick it up.

 

[Scuromondo]

An Excelsior, like the one in the picture, needed some attention (couplers) and I noted the unusual feature, circled in white, on the way along. This is a small, spring-loaded T-bar device hinged at the end where it fits to the accordion case and the top edge of the ’T’ rotates. A coil spring on the vertical leg of the ’T’ keeps the bar pressed against the reed blocks.
The reed blocks are secured in a fairly normal fashion with ‘standard’ sliding clips at the ‘high’ end. On first site the T-bar looks like it might be there to assist in keeping the blocks in position and secure but the coil spring is not very strong and as far as I can see adds little or nothing in a ‘securing’ sense. Is it reasonable to suppose that the T-bar’s function is to mechanically connect the (resonating) reed blocks to the outer shell of the accordion and thereby improve the sound?

It would be good to see a closeup, in clearer focus, of this feature if possible. Do you believe this is an original feature from the manufacturer, or the handiwork of a creative repair shop?

 

[boxplayer4000]

Thanks for your responses:
JerryPH: I think my attempt to describe the device in words has not been clear. The device does nothing to assist with lateral alignment of the reed blocks. They are already held very firmly at each end both laterally and vertically. I hope the drawing below will make it clearer.

tcabot: Some, I think, will be surprised to hear that the outer case of the accordion plays no part in how it sounds. Although the comparison is not completely the same a violin body has a lot to do with its sound (putting it very mildly). Also, consider the tuning peg in a violin and its purpose. You mention in your entry “putting the reed against” which kind of leads to the argument for mechanical connection to improve the sound. To build on this consider the difference when a tuning fork is held free and where it is ‘mechanically’ connected to, say a table top.

scuromondo: There was nothing about the device that made me think it was ‘home-made’. It looked to have been made with the usual care I associate with the Italians. Unfortunately I can’t get another picture as the accordion has been returned its owner.

 

[tcabot]

when a tuning fork is held free and where it is ‘mechanically’ connected to, say a table top

Yes, but to make this analogy more applicable to an accordion being played, imagine the audible effect that the table top adds to the tuning fork if there's a jackhammer operating right next to it, or if a jet is taking off above you. The very loud sound completely overpowers the fork and the table top amplifier: you won't hear either against the backdrop of a jet engine.
Same goes for the accordion box - the real overwhelming power comes from the reed pumping the air. The acoustically dead plywood (or solid wood for that matter) box won't be generating nearly enough db to have an audible effect.
The surface area of the top lid of the box (and its 5mm plywood thickness) is not nearly enough to drive any sound that would be audible against a sounding reed.
So directly connecting the reed blocks to the box, in my view is highly unlikely to have any noticeable effect at all.

In regard to the violin, the peg does not contribute to the sound at all - it is only there to hold the string. The string drives the bridge, which in turn drives the pre-loaded soundboard, and it is the soundboard vibrations that pump the air - and that's what you hear.

 

[boxplayer4000]

tcabot: My mistake: I used the wrong term re. the violin. It should have been 'tuning post' and not 'tuning peg' two entirely different parts of the instrument.
The external enclosure of the accordion is very important to manufacturers for sound diffusion as well as appearance. I had an occasion on expensive instrument to have to have to renew the treble grille. The makers wanted to be responsible for fitting the new grille as they suggested it should be fitted in a very particular way so as to be 'in tune' and diffuse the sound properly.

 

[debra]

Different forms of this have been used by several manufacturers, to keep the reed blocks in cassotto more firmly connected to the leather gasket under the blocks. Usually it is closer to the center, so I'm thinking that this one may be added by a previous repairer.
The reed blocks' underside needs to be perfectly straight so that the seal can be kept perfect without applying too much pressure on the ends of the reed block. If the block is pushed too hard onto the soundboard then the register slides will not move easily. It's a delicate balance between enough pressure to have a good seal and not too much pressure to keep the register slides moving "freely".

 

[boxplayer4000]

There's no room to fit it closer to the centre; by a previous repairer or not.
Observations about perfectly straight reed blocks, excess pressure/sticking slides apply to ALL accordions, cassottoed or not.

 

[tcabot]

to have to have to renew the treble grille

As far as I understand it, the treble grille is of huge significance, as the sound waves travel from the reed, through the chamber, out of the soundhole (in the "soundboard"). Then they bounce around the cassotto chamber if they are in cassotto, and then they travel through the grille. The grille acts as an acoustic filter.

The reed generates the waves: some go outside of the box via the soundhole and the grille, others go inside the box and bounce in there until they die. It it possible that by bouncing off the internal walls of the box, the generate enough movement in the box itself to pump some external air, but it's questionable whether that would be audible. We just don't process quiet sounds against loud background. Anyone who has ever tried having a conversation in a nightclub or at a rock concert knows this very well.
So it is possible that box materials and wall thickness contribute to the sound.

But the idea that passing vibrations from reed blocks to the box walls via a bridge will let the box pump an audible amount of waves externally is extremely hard to believe for me.

Re soundposts, I've never built anything with a soundpost, so don't have any hands on experience, but if a good 99% of what you hear in a stringded instrument is generated by the soundboard, and the soundpost directly interferes with the soundboard vibrations, then you can see why they are so important in the violin and viol family instruments.
An accordion equivalent would be the valves interfering with reed vibrations and affecting the volume, pitch and timbre.

 

[rhythmbox]

As the owner of the instrument about which the OP has opened this thread, I can confirm that I own two Excelsior model 940 models, this one and a special "Peppino Principe" model, both of which have this "gizmo", as someone described it (forgive me, I'm not au fait with technical terms). Bought years apart in different parts of the UK and with, I would suggest, an extremely low percentage chance that this is not a feature deliberately included by the manufacturer, who are renowned for their quality of manufacture, and not the brainchild/invention of a previous repairer...

Perhaps the purpose might be to prevent unwanted vibration, rather than to have any acoustic augmentation..? As I say, I'm no engineer... ;-)


Here's a picture taken from a 940 currently for sale on a Gumtree site in England...you'll see it has the same feature.

 

[Dingo40]

Could it be a mechanical dampner to eliminate unwanted vibrations?
Reverse engineering required!
Play with, then without?

 

[boxplayer4000]

Re soundposts, I've never built anything with a soundpost, so don't have any hands on experience,

I've not built anything with a 'soundpost' either but I've talked to experienced fiddlers, makers and professional players over the years, who have made me aware of what a tuning post is in their instrument. The location of the tuning post is internal and is a mechanical connection between the front of the instrument (strings/bridge) and the rear shell of the instrument. The tuning post came into my mind when I saw the device under discussion in this thread.

rhythmnbox: Thanks for the better photo. You certainly have a couple of good accordions there.

 

[tcabot]

mechanical connection between the front of the instrument (strings/bridge) and the rear shell of the instrument.

Oh yes, I understand the function (and the importance) of the soundpost quite well, but the key difference is that in such instruments it's the soundboard that generates the bulk of the sound that we hear. The sound post does not actually increase or objectively "improve" the efficiency of the soundboard - you don't fit them into carved-top mandolins (and I've built a few of those) or jazz guitars for example.

In our case it's the reed and its coupling with the air that we hear, while the front side of the accordion box is pretty much incapable of generating anything of significant acoustic value.

Nevertheless, the reed block retaining device (which I think this might be) is very interesting. I've got a Excelsior 921 model on my wishlist, so might get my hands on it at some point if I'm lucky.

 

[boxplayer4000]

tcabot: Tuning post/sound post.. whatever. You explain what you think the sound post DOESN'T do. It would probably help if there was an explanation of what it does do. A quick search of sites where it might be expected opinions are reliable show a generally held view in this clip:
This principal crossed my mind when I saw the accordion device a few weeks back.

 

[Scuromondo]

As the owner of the instrument about which the OP has opened this thread, I can confirm that I own two Excelsior model 940 models, this one and a special "Peppino Principe" model, both of which have this "gizmo", as someone described it (forgive me, I'm not au fait with technical terms). Bought years apart in different parts of the UK and with, I would suggest, an extremely low percentage chance that this is not a feature deliberately included by the manufacturer, who are renowned for their quality of manufacture, and not the brainchild/invention of a previous repairer...

Perhaps the purpose might be to prevent unwanted vibration, rather than to have any acoustic augmentation..? As I say, I'm no engineer... ;-)


Here's a picture taken from a 940 currently for sale on a Gumtree site in England...you'll see it has the same feature.

I apologize for a slightly off-topic response, but in the photo you shared I noticed that each of the plastic reed valves appear to be deliberately crimped. Is there some advantage to crimping valves? I have not seen this before, as I have understood that it is generally desirable for the valves to lie as flat as possible.

 

[Ventura]

good eye

i have noticed the mylar/whatever they are made of reedflaps
seem to pinch/catch against the leather/man-made-material main flaps
on occasion when used as half or 2/3 length boosters..

but i would have crimped the tips in the other direction,
to ensure a smooth liftoff

so i cannot imagine why these are crimped toward the flaps
unless he had the idea too, but got reversed in his head for
the logic of it

i predict they will catch a lot more often than flats and end up
being a nice try but.............

 

[tcabot]

@boxplayer4000
I see where you got the idea from, but I'll try to explain a bit further without going into stringed instruments acoustics:
What you hear in a stringed instrument is the top. The back, the bridge, the air cavity, the sides, the soundpost - all can interfere with how the top works. But you hear the result because what you hear in a stringed instrument is the top. You don't need a soundpost to transfer vibrations from the top to the back - that's already happening via the air cavity and via the sides, and it already affects how the top vibrates - this is an extremely complex process that has been very well described in highly respectable literature (as opposed to online forum lore). If you are really interested in this, Trevor Gore Vol 1 is one of the best works on the subject.
The post changes the way the top vibrates. It most likely changes the way the back vibrates, which in turn likely affects how it's coupled with the top via the air cavity, which in turn further changes how the top vibrates. But it's all about the top.

The front face of the accordion box is not a soundboard. I am 99.9% certain that the front face of the accordion box is incapable of producing any meaningful acoustic contribution against the backdrop of the powerful sound generated by the reed that you hear when playing the accordion. It's all about the reed and the sound path between the reed and your ears. So driving a small 5-mm thick strip of plywood (covered with a fat layer of celluloid) with a small metal post linked to the reed blocks it makes no sense.

 

[boxplayer4000]

Scuromondo: The crimping you see on the valves is a fairly standard way of getting some more life out of valves which are becoming tired.
It lasts for a while but sooner or later renewal will be required.

You don't need a soundpost to transfer vibrations from the top to the back

tcabot: With respect, this is something should share as soon as possible with violin makers.

 

[pitzelberger]

My Excelsior has an identical „sound post“. I occasionally forgot to put it back in place, but have not realized any difference while playing the accordion.