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

[Winslow Yerxa <winslowyerxa@xxxxxxxxx>]

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: 

1) Remove the covers.

2) Loosen all the reedplate screws perhaps two turns.

3) Test for thread cutting. The screws may cut their own thread in the assembly process and this process is not always completed at the factory. Starting 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. 

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) The 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: 

1) remove the covers.

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

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. 

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
            Harmonica Basics For Dummies, ASIN B005KIYPFS
            Blues Harmonica For Dummies, ISBN 978-1-1182-5269-7
Resident Harmonica Expert, bluesharmonica.com
Instructor, Jazzschool for Music Study and Performance


________________________________
 From: Trip Henderson <trip.tunes@xxxxxxxxx>
To: harp-l@xxxxxxxxxx 
Sent: Monday, August 27, 2012 6:45 PM
Subject: [Harp-L] XB-40 report, Hohner Crossover question
 
Here's a follow up to my previous question as to what to expect from
Hohner's customer service after receiving a poorly tuned XB-40 (from
Elderly Instruments who do not take returns on "mouth instruments"). Hohner
was great, they replaced the instrument, no questions asked, quick turn
around. Yeah Hohner!

Now, how do I get this thing more airtight? I work on my Filisko/Sleigh
harps (tune, change reeds) but have not had to emboss, etc. Any advice
greatly appreciated.

A friend asked me to work on his MB Crossover, key of D. Are the parts in
these harps the same psychical dimensions as standard Marine Bands?

Thanks for the know how!


-- 
Trip Henderson
www.youtube.com/user/tripharmonica
<http://www.youtube.com/user/tripharmonica>
www.reverbnation.com/thewhistlingwolves
www.youtube.com/user/TheWhistlingWolves