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Weak highs on Hybrid concertina.


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Hello folks, 

 

I recently acquired an AC Norman 30b anglo in mostly good functional condition, and while I normally have a decent mechanical relationship with concertinas (that is, I can work on most things without being too baffled), there's an issue thats throwing me for a loop and its driving me a bit mad. The topic of reed volume is discussed often, and rest assured I investigated as deeply as possible before posting this query 

 

The instrument is mostly fast, bright and loud, which I absolutely love, but the right hand first row (closest to the player) and a couple accidentals are uncommonly feeble and require a higher degree of pressure to sound when compared to the rest of the instrument. This of course makes for a terribly imbalanced experience and the lows end up easily drowning out the highs. It also renders ornamentation nearly useless.
The highs are weak to start and will eventually sound but far too weakly. 

 

My first thought was 'must be the set of the reeds'. So I popped her open and found that the set is actually quite good. No choking, just weak volume and slow. 

 

Then I pondered, 'perhaps the valves?', and while the valve on the b/a button needs replacement and several others appear to have spots of mold or mildew (eek), the other higher reeds of course lack valves, so that would bring one back to reed set again. 

My next assumption was perhaps gaps in the reedpan, but this doesn't seem to be a problem. 

 

The final conclusion ive drawn so far is that perhaps its the material that is attached to the reed pan. Its some sort of, I dunno, papery, ribbed material. it appears to be common for AC Norman concertinas. Is it some sort of gasket that once upon a time was spongey or soft to some extent? Does anyone have any experience with this material? 

 

I feel like this is most likely the culprit because I can't imagine what else would be the cause at this point. Bellows are sound, reedpans are dead straight, pads are fine, valves are mostly missing (as they should for these high notes i imagine). 

Any other ideas, folks?
 

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I don't mind starting the discussion - firstly congratulations on your purchase. it looks like a very well made instrument in excellent condition.

Secondly the reed gaps look too small in the photos.

Everything else looks very good.

Best of luck

Tiposx

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Thanks for your reply and the kind words!

 

The reed tongues seem to be nearly perfectly parallel to the plates, and while id figured it might help to create a higher set, the symptoms didn't correlate to what I commonly hear for low set; that a low set reed would sound quickly, but choke under higher pressure and would also be too quiet. 

 

My problem here is that the reeds are slow to speak, can be pushed to be much louder without any choke up and sound like a typical reed, but the overall pressure requirement is too high and imbalanced.

 

That would normally point to bad valves perhaps, but without many valves present to begin with (because high notes) its a bit perplexing!

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Perhaps the reed plate holding-down screws are loose?

 

I would try adjusting at least one of the reed gaps. I aim to see an even gap around the tip area, the same height as the thickness of the reed is a good starting point. It really helps to judge the gap if there is a bright light under the reed.

Edited by Tiposx
Reed plate, not reed
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On Traditional concertinas, the very high reeds were often not valved, this could leave them breathy and weak sounding. The reason for not valving was that the reed would not start sounding as the valve choked air flow instead of opening. The solution was to clip the tip of the related valve to permit initial air flow when starting the reed. Yet there would be enough of the vent covered, on bellows reversal, to prevent breathiness or dual note sounding. You might wish to consider this for an experiment.

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I have seen the insides of many melodeons and accordions over the years, and have noticed that the reed plates for the very highest notes, have three factors that differ from the lower reed plates. 

1) They are valveless; like yours.

2) The reed plates are are reversed, so that the tongue tip is closer to the opening.

3) The tone chamber has a wedge shaped insert in it to reduce it's volume.

 

On the prototype Russian Hayden System Concertina, where all the reeds of each side were on a single plate; one pair of reeds on the left hand side was accidentally put on the wrong way round so that the tips of the reeds were next to the opening. This note absolutely barked out considerably louder than than the other notes ! 

 

Inventor.  

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Alright, I've tried a few things as suggested on the B/A reed, which is the one that has been making me the most sad. 

 

I first tried rotating the reed, and while volume increased slightly, the timbre changes quite a bit as a result of the reed moving closer to the pad opening. Its a lot brighter and tinny sounding, which makes it audibly imbalanced for other reasons. I was hopeful about this but alas, it didn't completely help. 

 

I tried gasketing the reed a little to see if it was a leakage issue but it seems to have no additional affect, so onto the next option;

 

I replaced the old leather valve for the A side of the reed with a mylar valve and trimmed the tip off, leaving a 2mm opening at the end. This seems to have altered things a tiny tiny bit, but it has not made the reed particularly louder, but I am curious about doing the same for the B side. 

 

One thing that is bothering me is that I can't tell if there's a standard for whether the b/a button (second button, first row, right hand side) is valved at all. Some folks seem to put valves on it, but its hard to find photos of hybrid reed pans, oddly enough. 

 

I considered the proposed idea of making the chamber for the reed smaller, but unlike concertina reeds, accordion reed chambers don't seem to have available room for this alteration. I imagine the only thing you could do is make the chamber more shallow, but I wonder what other effect this might have. I cant wrap my head around it. With s concertina reed, you can sort of change the chamber sizing as ive seen done a number of times but im at a loss for hybrid reed pans. 

 

I might give altering the height/set of the reed another go. I tried adjusting the height a number of times but it gets pretty hairy with higher reeds. I have had one accordion reed break in the past this way, so im a bit wary, but at least they're easy to come by. 

 

I may order a spare in just in case. 

 

Anywho, can anyone answer as to whether this reed should be valved to begin with? I think I tried the A side with no valve before but it seemed to respond more slowly or a bit too breathy. Perhaps a shorter valve combined with a higher set would help

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Whether valves are required or not really just comes down to how the reed sounds.  Try it without and see if that helps. 

 

In accordions the chambers for the highest pitch reeds may have a wedge shaped insert of wood the reduces the volume by about a third to a half.  If the reed tip is furthest from the vent then the wedge needs to be thinner on the side facing the inner reed.  If that's not clear I'll take a photo.

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