Fwd: [Harp-L] XB-40 report, Hohner Crossover question

[burket@xxxxxxx]

Thanks for the detailed overview Winslow.  This is definitely going in my tech./ repair library of wisdom!
I appreciate Trip's diligence in making the XB's sound better and bringing this up here.  
Keep us posted how it all works out and if you achieve good results.

Rick Epping's previously posted tips on cleaning and re assembly gave new life to my G- XB.
The valve's had become very sticky and inconsistent.  After a good cleaning, I only had to
replace one windsaver and it was good as new.

Burke T.

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Message: 2
Date: Tue, 28 Aug 2012 09:50:56 -0700 (PDT)
From: Winslow Yerxa <winslowyerxa@xxxxxxxxx>
Subject: Re: [Harp-L] XB-40 report, Hohner Crossover question
To: Trip Henderson <trip.tunes@xxxxxxxxx>,	"harp-l@xxxxxxxxxx"
	<harp-l@xxxxxxxxxx>
Message-ID:
	<1346172656.46183.YahooMailNeo@xxxxxxxxxxxxxxxxxxxxxxxxxxxx>
Content-Type: text/plain; charset=iso-8859-1

The XB-40 tends to be good out of the box but it sounds like the one you got was 
an exception.

Reeds can be gapped and arced and slot can be sized, and these are worth doing. 
However, if the harp is leaky I would first check the assembly, which can be 
fixed with a screwdriver, eyes, and hands. Flattening the comb is probably not 
needed.

The first fix I'd recommend is the simplest: Loosening and re-tightening the 
reedplate screws. To do this:ï

1) Remove the covers.

2) Loosen all the reedplate screws perhaps two turns.

3) Test for thread cutting.ïThe screws may cut their own thread in the assembly 
process and this process is not always completed at the factory.ïStarting at the 
middle of the reedplate and working outward toward the ends, try re-tightening 
the screws. Once the screws begin to resist finger pressure on the screwdriver, 
keep up the pressure, but do not use much force, just enough to test for further 
screw motion. If the screws pass through a stage of resistance and then become 
firm and no longer budge, you've finished the thread cutting. Now lossen the 
screws again and go to the next stage.

4) Re-tighten the screws, again working out from the middle of the reedplate. 
This time, tighten only until the screw resists finger pressure on the 
screwdriver (finger tight).

If your harp is still leaky, check for surface mating of the parts.

The comb actually consists of three parts:

- top half

- bottom half

- mouthpiece

Al three pieces need to fit together properly, and the reedplates need to be 
aligned with them as well. Leaks can occur as a result of misalignment of any of 
these parts.ï

Things to check for:

1) Reedplate alignment. Look at the side of the harmonica and focus on the area 
where the front edge of the reedplate juts out past the front of the comb to 
rest on a ledge that runs along the back of the mouthpiece. Also run a thin shim 
along the front edge of the reedplate toe ensure that thre is no significant gap 
between the front edge of the reedplate and the back of the mouthpiece.

2)ïThe comb has a top and bottom half that need to fit together properly. A seam 
runs along the comb halfway through its thickness; this is where the top and 
bottom half mate. Try running a fingernail across that seam along its length. 
The seam may form a slight peak, but if your nail snags on one half rising to 
jut out, you may need to bring the halves into better alignment so that they 
forma good seal with the mouthpiece.

Hohner uses a sealing substance with a consistency like that of lip balm on the 
mating surfaces between the mouthpiece and the comb halves. I don't remember 
whether they also use this on the two halves of the comb. You can renew this, 
although I don't usually bother with it.

To correct misaligned parts:ï

1) remove the covers.

2) slightly loosen the reedplate screws and the mouthpiece screws - just enough 
to allow the parts to move slightly.ï

3) Place the front of the mouthpiece on a hard, flat surface and then press both 
halves of the comb forward toward the back of the mouthpiece.ï

4) Holding the parts firmly together, check the placement of the front edge of 
the reedplate visually and the seams between the top and bottom halves of the 
comb. Reposition as necessary.

5) When parts are in good alignment, tighten the mouthpiece screws and then the 
reedplate screws, working outward from the middle and tightening only until the 
screws resist your fingertips.

Hope this helps


Winslow Yerxa
Author, Harmonica For Dummies, ISBN 978-0-470-33729-5
ïïïïïïïïïïï Harmonica Basics For Dummies, ASIN B005KIYPFS
ïïïïïïïïïïï Blues Harmonica For Dummies, ISBN 978-1-1182-5269-7
Resident Harmonica Expert, bluesharmonica.com
Instructor, Jazzschool for Music Study and Performance