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Diagnosing A Minor Problem


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#1 Dave Weinstein

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Posted 04 September 2003 - 08:42 AM

So, I have one minor glitch in my Lachenal.

The notes (both notes) on one key (d/c#, left most button on the right side bottom row), will regularly (but not always) get a little "hiccup" on a long note play (sometimes in the middle, sometimes near the end), and it may get a timbre change after the "hiccup".

Since it is both notes, I'm assuming it isn't the reeds.

Does anyone know of a valve issue that might be cause this sort of symptom?

I haven't opened it up yet because I'm afraid to inadvertantly disable the instrument.

--Dave

#2 Richard Morse

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Posted 04 September 2003 - 12:35 PM

That does sound like a valve problem, particularly if you play that note a low volume and slowly increase volume.... at some point the pressure/air flow will overcome the faulty valve's set (bent away from the plate) and suck it against the reedplate which will cause a discernable "pop". Before that the reed will we slightly breathy sounding and not very loud. After the valve seats the tone will become immediately clearer and noticeably louder.

If so, this is quite indicative of a dead valve. Concertinas are made to be easily opened and fooled with (with the vintage style ones being markedly easier than Stagis).

#3 Dave Weinstein

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Posted 04 September 2003 - 01:35 PM

Is this a "replace the valve" sort of issue (or likely to be) or a "push here" sort of issue?

--Dave

#4 Richard Morse

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Posted 04 September 2003 - 06:13 PM

Depends upon the problem. If the bum valves are beat because you use them so much and the rest are in fairly good shape, you can give them a little more life by reshaping them.

A quick fix (short term) is to take a crisp screwdriver and (held perpendicular to the valve and reedpan) and lightly scrape the valve in place. That will stretch the "outside" of it making it want to rest against the reedpan rather than bent back away from the reedpan. This could last from several hours to several weeks.

I do not recommend the medium fix which is to remove the offending valves, curl them around and back and forth in your fingers and reattach it (we use thickened shellac). This can last several weeks or more. The bad news is that a reed usually changes pitch when you replace its valve and so should be retuned. Not a task for a novice.

A better medium fix is to have the few offending valves replaced with new (and associated reeds retuned (by a pro).

Dying valves usually make themselves known on the most-used reeds first and herald the rest following suit. Depending on how persnickety you are, you can put up with things - or do the quick fix when they irk you enough - or do the better medium fix, though really if several are going the rest won't be far behind. Consider having the entire box revalved (and tuned). By a pro.

#5 Dave Weinstein

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Posted 04 September 2003 - 06:57 PM

The instrument was revalved (and repadded, and retuned) this spring, just before I bought it.

So it sounds like it is most likely just a bad valve or valves (since it has done this since I got it), rather than valves wearing out over time.

How much is a checkup likely to cost, and how long is it likely to take?

--Dave

#6 Richard Morse

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Posted 05 September 2003 - 07:04 AM

If it's just been overhauled it sounds like a poorly installed valve. Sometimes a valve can be inadvertantly secured on the reedpan a bit too close to a chamber wall so when it opens it rubs against the wall and gets hung up there. Asymetrical gluing can also cause this problem

An easy fix is to gently stretch it with a crisp screwdriver rub to have to move away from the chamber wall. If that doesn't work you can remove it and reinstall it properly. If secured on with exactly the same amount of coverage, the pitch of the reed should not change noticably.

Another possibility is that you have "bad" valve. They are cut with the grain of the animal along the long axis of the valve. Sometimes a valve gets punched from a diagonal grain which will make it open slightly askew (to hang up on the chamber wall). Sometime there's a natural crease in the leather skin which causes the valve to be weaker (not as springy) and remain open, or open askesw

If you have a concertina repairer replace a valve or two, it would probably take about 10 minutes. I would imagine that the person who overhauled yours would probably do it for free. Others may charge you a slight amount.

Edited by Richard Morse, 05 September 2003 - 07:09 AM.


#7 Dave Weinstein

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Posted 05 September 2003 - 10:34 AM

The restorer is somewhere in the UK, so it would be more expensive (and more trouble) to ship the instrument back and forth across the Atlantic.

I'll most likely get it a tuneup (a few of the notes are a few cents sharp as well) and checkup after I get my new Tedrow. Getting it looked at now would mean going without a playable instrument for days!

Thanks again,
--Dave

#8 d.elliott

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Posted 05 September 2003 - 03:23 PM

Dave,

can you clarify if the notes with the 'hitch' sound on belows closing or opening?

Taking Rich's point; if the problem is on expanding the bellows it is more likely to be the valve in the chamber, probably catching on the chamber wall.

Somethimes the valves are punched correctly to grain, but not quite squarely through the leather, this can leave the 'fluffy' side (underside) of the valve protruding out on one edge, a little from its top surface. If this protrusion is to the chamber wall, then it can be catching without being obvious. Use a scalpel or small scissors to trim off the excess 'fluff'. Then stretch the valve as Rich describes, it usually works.

Dave

#9 Bob Tedrow

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Posted 05 September 2003 - 04:38 PM

ok, here's my 2 cents:

Dont fool with the established "stasis" of the offending valve by rubbing, pulling massaging etc. that often only works for a little while anyway.

If you do not want to or cannot replace the valve with a new one. Try this, as long as the valve is not hideously curled and stiff as a poker.

1. remove the offending valve

2. remove the old adhesive with a sharp chisel, fingernail etc from both the wood and the valve

3. apply the appropriate adhesive to the appropriate spot on the reed pan

4. Now listen up good right here. Sit down and pay attention. With the tip of an awl or very small screwdriver, press just the tip of the valve firmly in its place.

Then:
Very sweetly and gently, lightly press the bottom of the valve into the adhesive...... I said lightly.

Allow the valve to assume a functional position, closed at rest. Allow whatever curly nonsense to be expressed at the bottom of the valve where it make no difference.

Let it dry, give it a try.



Bob Tedrow

Edited by Bob Tedrow, 07 September 2003 - 05:14 PM.


#10 Dave Weinstein

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Posted 09 September 2003 - 08:27 AM

If I play a very slow draw on the C#, the bellows move, and there is a hiss, but the reed doesn't sound.

If I play it normally, the reed sounds.

The "hiccup" is mostly noticeable on long notes, especially if I'm running out of bellows play.

I forgot to check the very slow push on the D to see what that would do.

--Dave

#11 d.elliott

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Posted 09 September 2003 - 11:51 AM

Check that the 'set' of the reed tongue above the reed frame is not excessive compared with similar reeds of the same size.

However I still favour a valve problem, is the reed on the chamber side or the underside of the reed pan?

Dave

#12 JimLucas

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Posted 09 September 2003 - 02:35 PM

Dave Elliott asked:

...is the reed on the chamber side or the underside of the reed pan?


But Dave Weinstein began with:

The notes (both notes) on one key (d/c#, left most button on the right side bottom row), will regularly (but not always) get a little "hiccup" on a long note play (sometimes in the middle, sometimes near the end), and it may get a timbre change after the "hiccup".

Since it is both notes, I'm assuming it isn't the reeds.


I suppose it could still be a valve that catches on something where it's halfway open. Catching in both directions, it might eventually break free in the one direction from half open to full open and in the other direction from half closed to fully closed. But that's theoretical; I've never seen it, and I have no reason to assume that result as far as sound is concerned would be the same in both directions. Two valves -- or reeds -- with the same problem... that just happen to be in the same chamber? Well, I've experienced stranger coincidences.

#13 Dave Weinstein

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Posted 09 September 2003 - 08:18 PM

The slow push on the D does not exhibit the same silence as the draw on the C#. However, as the bellows nearly close, there is a sudden noticeable shift in timbre on the D, which is I suspect what I was hearing.

The C# issue is far more noticeable.

--Dave

#14 Richard Morse

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Posted 10 September 2003 - 06:51 AM

The slow push on the D does not exhibit the same silence as the draw on the C#. However, as the bellows nearly close, there is a sudden noticeable shift in timbre on the D, which is I suspect what I was hearing.

Ah, that's an easy one, a well-known problem! That reed is being affected by the bellows fold as it nears it. Anything near the tip of a vibrating reed will make it's pitch shift to slightly higher then a light "burring" or buzzing tone, sometimes with metallic or nasal overtones.

Open her up and you'll probably find that the linen or leather hinge on the inside bellows fold is loose/deteriorating (or possibly had been replaced with a thicker-than-original, or often a newer hinge placed on top of the original - making it a lot thicker). Sometimes (much more rarely) the adjacent bellows card had become damaged and is intruding.

Repair as is necessary and you're back in good shape!




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