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Author Topic: Recording king repair  (Read 24990 times)

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Theo

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Re: Recording king repair
« Reply #160 on: February 09, 2018, 08:37:57 AM »

It’s not as simple as a static pressure difference.  Air is flowing so pressure is different at different positions along the air path, and that’s not all.  There is also vibration of the reed tongue and sound waves interacting with the various shapes of the reed chamber and its vent which all happen dynamically. I don’t  understand it in any detailed theoretical way but I do have a good practical understanding of what can happen when you change various features.

I was reminded of this yesterday shortly after posting the photo of the instrument I was tuning.  On finishing the job I gave the instrument a test drive and all was well accept that the lowest F# on both rows had no tremolo, the rest was based on 439/441, so a 2Hz swing which is a quite obvious difference from no swing.  Having seen similar problems before I knew that the answer was not to widen the spread on the F# reeds, but to fit a link attached to the top of the two reed blocks.  Immediately he F#s played correctly.
« Last Edit: February 09, 2018, 08:40:30 AM by Theo »
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Theo Gibb - Gateshead UK

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Steve_freereeder

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Re: Recording king repair
« Reply #161 on: February 09, 2018, 08:48:04 AM »

My tuning bellows are made from a large melodeon-sized bellows 33 cm x 18 cm. The solid base is 9 mm ply; the top is also 9 mm ply but with a cut-out nearly as large as the internal dimensions of the bellows. There is an 8 cm external overlap lip on 3 sides and a 10 cm lip on one end which serves as a handle for moving the end of the bellows up and down. A similar overlap on the base allows the assembly to be clamped to a table or workbench. The top is covered with chamois leather to provide an air seal.

If I am tuning reed blocks out side of the instrument, I have a 3 mm ply top clamped to the top surface of the bellows, which has a square port the same dimensions as the air hole in the reed blocks. I simply hold the reed block in place on the top by firm hand pressure whilst sounding the reeds, taking care always to always place my hand in the same place. Different hand position and hand pressure can affect the pitch.

Because of the pitch discrepancy on the tuning bellows, I always tune by off-sets. In other words, with each reed bank isolated by a strip of paper so only one set of reeds is sounding, I measure and record the actual pitch in situ in the instrument first, then calculate how much it needs to be altered to bring it into tune. Then I do the same with the reed block on the tuning bellows and change the pitch of each reed by the required amount. When replaced in the instrument, I find this usually gets me to within 1 cent of the required pitch.

However...
My preferred method of tuning these days is to keep the reed blocks in situ and place the entire open end of the instrument directly over the large opening in the tuning bellows. If the instrument is smaller than the tuning bellows opening, I can reduce the size of the opening to suit, by using a one or two 3 mm plywood strips covered with chamois leather, which I can butt up to the sides of the instrument and clamp into place on top of the tuning bellows. This works very well and the pitch discrepancy between the tuning bellows and the fully assembled instrument is much reduced. For very accurate tuning (within 0.5 cents - e.g. when a very light tremolo is required) I record the off-sets required and adjust the tuning accordingly.

As always, the final tuning process is always to use your ears - listen to what the instrument sounds like when fully assembled and make final, minor, adjustments as needed. 

Post-script:
Have just read Theo's latest and fully agree with what he's written. Theo taught me how to tune and I'm constantly grateful to his patience and generosity.  :|glug
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Re: Recording king repair
« Reply #162 on: February 09, 2018, 08:55:22 AM »

... Having seen similar problems before I knew that the answer was not to widen the spread on the F# reeds, but to fit a link attached to the top of the two reed blocks.  Immediately the F#s played correctly.

Theo - do you sometimes fit more than one brace across the reed blocks? I know that you usually fit one somewhere near the middle of the blocks if there isn't one there already, but your comment suggests that you fit an additional brace near the lowest pitched end of the reed blocks.
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Steve
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Theo

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Re: Recording king repair
« Reply #163 on: February 09, 2018, 09:13:10 AM »

In this case there was no link fitted so I just fitted one which cured the problem.  Very occasionally I have had to fit a second link, but one is nearly always sufficient.
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Theo Gibb - Gateshead UK

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malcolmbebb

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Re: Recording king repair
« Reply #164 on: February 09, 2018, 02:28:01 PM »

So if I understand you Malcolm your reeds are doing what mine are doing? Becoming sharp when installed in the box. Maybe it is the top thickness then.
The table was just made from some wood lying around, probably nearer 3/4". No reason then to think it might not be suitable. Bellows is a mid-size PA bellows.

First time I did it I had tuned slightly sharp with the reed off the block and was quite a long way out. I was also using a little adaptor to hold the reed which made matters worse.
I was wondering about the hole size, 11mm dia from memory, I will review that.

I was seeing variation day to to day also, but haven't played with it for a while to remember numbers, maybe that will improve too.
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boxcall

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Re: Recording king repair
« Reply #165 on: February 09, 2018, 02:45:45 PM »

So if I understand you Malcolm your reeds are doing what mine are doing? Becoming sharp when installed in the box. Maybe it is the top thickness then.
The table was just made from some wood lying around,
Yes pretty much what I did, no need to spend more than you have to, plus being a carpenter I have lots of cut offs.

There is also vibration of the reed tongue and sound waves interacting with the various shapes of the reed chamber and its vent which all happen dynamically.
Would this explain what I think is happening, which is when I tune one side of a reed and get it to pitch then tune the other side it changes the pitch of the first tongue I tuned?
Or maybe I'm just getting different reading because of moving the position or applied pressure.
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Theo

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Re: Recording king repair
« Reply #166 on: February 09, 2018, 02:58:40 PM »

I have not noticed that, except if you turn the reed plate over?
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Theo Gibb - Gateshead UK

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boxcall

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Re: Recording king repair
« Reply #167 on: February 13, 2018, 09:49:59 PM »

Well Theo, I was flipping the reed during pretuning and that's where I was noticing that affect.


So here's another recording of the G and C rows, first playing a chord then root and fifth , then root and third on both octaves, then the scale two octaves.

I also went though the basses separate and together, although mixed up in spots.

Any comments on sound good / bad , needs more tremolo here or less there , this note is flat or sharp, etc. are welcome, this tuning business is like painting where your not sure if it's done yet ( for Me anyway).
 
https://soundcloud.com/boxcall/rc-test-two

Funny when i was playing this to my iPad using GarageBand and the fun mode and the clean setting this sounded ok or like your hearing it and like I'm hearing it. But using the fun mode with extreme tuning setting some of the notes sounded bad out of tune on playback( the sixth note on G row was the worst), I wonder if that's telling me something I'm not hearing? I guess if I'm not hearing it it doesn't matter.

Well what do you think?


« Last Edit: February 14, 2018, 01:13:15 PM by boxcall »
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malcolmbebb

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Re: Recording king repair
« Reply #168 on: March 03, 2018, 10:49:01 PM »

For completeness, I have since modified my tuning table to inset some ply with a thickness of 5-6mm. The tuning between the table and the box is now much closer, although I have only tried it with reeds waxed on blocks so far.
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Dino BPII.
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Steve_freereeder

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Re: Recording king repair
« Reply #169 on: March 03, 2018, 11:21:50 PM »

For completeness, I have since modified my tuning table to inset some ply with a thickness of 5-6mm. The tuning between the table and the box is now much closer, although I have only tried it with reeds waxed on blocks so far.
Malcolm, what sort of difference are you now finding between the reeds on the blocks sounded on the tuning table, and when they are in situ in the instrument?
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Steve
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boxcall

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Re: Recording king repair
« Reply #170 on: March 03, 2018, 11:30:37 PM »

I might have to try that at some point, did the reeds register slightly sharp out side the box?
Theo said His would be slightly sharp outside the box on the table which was just the opposite of what I was getting ( and I think you were too).

I posted a sound clip (THOTM fast tunes ) of the box being played if anyone wants to hear it.

http://forum.melodeon.net/index.php/topic,21945.0.html#lastPost

Or here https://soundcloud.com/boxcall/drowsy-maggie1


Edit: after seeing Steve's post, yes I would like to know that too
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malcolmbebb

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Re: Recording king repair
« Reply #171 on: March 04, 2018, 02:59:56 PM »

Not sure how helpful this is, as the reeds to hand are on blocks with valves fitted.
Using Dirk's, with both reeds sounding but only noting the lower one of the pair:

    Table    Box
G4  -2      -3
A4   0      +1   Dunno why, but consistent

G5  -1      -1.5
A5  +1.2    0

It seems generally consistent from playing around last night, I had around 2 cents in mind, most slightly sharp on the table. I can't remember how far out is was before, other than saying it was more! and noticeably flat on the table.

There are two other simple and maybe very obvious enhancements:

1) A pencil line through the centre of each hole, extending outside the reedblock, so I can align the reedplate/block over the hole.
2) A simple guide - presently a straight edged plywood offcut held in place with a couple of spring clamps - to locate the reedblock in the other direction.
So I know the reedblock holes are accurately over the table holes. Previously done by eyeball, but incorrect positioning or a little bit of movement could easily make several cents error between checks.
The holes are a slightly sloppy 11mm, drilled 11mm then the edges cleaned up. The block to hand also has slightly oversize 11mm holes.
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Steve_freereeder

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Re: Recording king repair
« Reply #172 on: March 04, 2018, 03:28:22 PM »

Not sure how helpful this is, as the reeds to hand are on blocks with valves fitted.
Using Dirk's, with both reeds sounding but only noting the lower one of the pair:

    Table    Box
G4  -2      -3
A4   0      +1   Dunno why, but consistent

G5  -1      -1.5
A5  +1.2    0
That's pretty close! My set-up generally results in ~5 cents sharp on the tuning table. Knowing that it will be different, I live with it and if I have to tune with the reed blocks on the table, then I apply whatever off-set is needed to tune to the pitch I need. Otherwise I tune with the reed blocks in situ in the instrument.

Quote
There are two other simple and maybe very obvious enhancements:

1) A pencil line through the centre of each hole, extending outside the reedblock, so I can align the reedplate/block over the hole.
2) A simple guide - presently a straight edged plywood offcut held in place with a couple of spring clamps - to locate the reedblock in the other direction.
So I know the reedblock holes are accurately over the table holes. Previously done by eyeball, but incorrect positioning or a little bit of movement could easily make several cents error between checks.
Yes - I do these things too.  (:)

Quote
The holes are a slightly sloppy 11mm, drilled 11mm then the edges cleaned up. The block to hand also has slightly oversize 11mm holes.
The holes on my tuning table top are square. Initial hole made with a drill and then filed to a square shape. The dimensions are about the same as yours - just slightly wider than the reed block vent openings. I don't use Dirk's Tuner so I only ever have one reed sounding at once.
Otherwise I think we both have a very similar set-up and methodology.

Thanks for sharing!
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Steve
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Steve_freereeder

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Re: Recording king repair
« Reply #173 on: March 04, 2018, 03:35:42 PM »

Further to my last:
You note a consistent anomaly for your A4 reed. That's interesting; I have a similar anomaly when tuning F#s. I've come to the conclusion that it is something to do with the particular acoustic resonance of my tuning bellows and/or the room in which I work. I suspect the latter mainly, as I usually have to move my electronic tuner and its built-in mic to a different location, either sitting in contact with the tuning table top, or else a couple of feet off to one side and the mic facing away from the room wall.
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boxcall

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Re: Recording king repair
« Reply #174 on: March 04, 2018, 05:21:21 PM »

Not sure how helpful this is, as the reeds to hand are on blocks with valves fitted.
Using Dirk's, with both reeds sounding but only noting the lower one of the pair:

    Table    Box
G4  -2      -3
A4   0      +1   Dunno why, but consistent

G5  -1      -1.5
A5  +1.2    0

It seems generally consistent from playing around last night, I had around 2 cents in mind, most slightly sharp on the table. I can't remember how far out is was before, other than saying it was more! and noticeably flat on the table.

There are two other simple and maybe very obvious enhancements:

1) A pencil line through the centre of each hole, extending outside the reedblock, so I can align the reedplate/block over the hole.
2) A simple guide - presently a straight edged plywood offcut held in place with a couple of spring clamps - to locate the reedblock in the other direction.
So I know the reedblock holes are accurately over the table holes. Previously done by eyeball, but incorrect positioning or a little bit of movement could easily make several cents error between checks.
The holes are a slightly sloppy 11mm, drilled 11mm then the edges cleaned up. The block to hand also has slightly oversize 11mm holes.
My reeds were waxed in the blocks with valves and I was doing the same thing for alignment using straight edge clamped to table and centering line, the hole in my table is round but slightly bigger than the hole in the block. So I guess I'd have similar results if I thin out my table top. You said you made a insert so I assume the top just needs to be thin in the area of the hole.
Your results seem pretty close to right on.
I think I've tune the RK all I'm going to for now, for it doesn't seem to bad and I don't think I've got the skills to make it much better  (:)
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malcolmbebb

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Re: Recording king repair
« Reply #175 on: March 04, 2018, 06:06:53 PM »

My bellows are glued to the table frame. I worked out where the inside of the bellows would come, and a further area just over an inch wider all round.
Routed out the wider area to inset some ply, and cut the inside-the-bellows area right out. Tied the bellows tightly closed to avoid trapping dust, and frequent use of vacuum.

There were a few mistakes. The ply was supposed to be 5mm but I didn't tighten the depth stop enough and went too deep. But I had some 8mm ply - so I used that then routed the underside to 5mm (ish!) to match the hole. Just out of cussedness, really, I doubt it made any difference. And a couple of slips with the (new - first time used) router.

The twin holes are D-shaped because the ply tore in the middle when drilling so I cut it out and patched a piece in. Easier than filling.
Two coats of Danish oil to stop it getting grubby. The duct tape is used to cover the hole(s) that are not in use.

The other side of the ply had a lovely grain pattern but somebody had marked it with permanent marker which I thought too deep to sand out.  :(
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