Re: [Harp-L] remark on the XB

[Zombor Kovacs <zrkovacs@xxxxxxxxx>]

Hi Winslow,

I said 50%. If it is an exaggeration or not, everybody
has to judge himself. It was only a number based on a
feeling. I remember when I bought my first XB key C, I
was completely disappointed. I almost sent it back to
the factory. It was leaky and squeeky like hell. Reeds
were buzzing and of course it was playable, but it was
far from good. Not for 90 euros, just for being a
harmonica. I was disappointed. But instead of
complaining at Hohner, I took it apart and sealed it.
The difference was very significant. To me at least.
And I am not saying that harps of other owners on the
list could not have been perfect out of the box. I am
saying that mine were not good. 

I am not sure what buzz you are talking about. If its
a low key, the reed might hit the comb somewhere. If
not, it can be an interference. E.g. you blow one of
the blow notes and the note interferes with the draw
section responder reed belonging to the same hole.
This means that the valve does not close well. It
depends on what buzz we are talking about. If the
valve does not seal well, you will get an interference
buzz. 
You may also get an interference buzz if air leaks
from one chamber to a neighbouring chamber, which can
easily happen. 
The problem with the XB40 is that the separating
chamber walls are very thin, not enough surface to
prevent air flow through. On top of this all,
reedplates are only bolted to the body at the edges in
a line. Nothing in the middle and as the harp is wider
than a normal one, there is not enough force in the
middle of the reedplate to press the reedplate against
the comb. 

The next thing is that responder reeds also leak air.
Some of them are not sank enough into the slot. Try
pushing them deeper into the slot. THey will still
work perfectly and leak much less. This is one of the
things.

How did I seal it? I am working for Henkel-Loctite as
an adhesive and sealant specialist. I have been using
one of our stuff called Terostat MS 930. 

http://www.sindby.dk/media/terostat-ms-930.jpg

It is a silicone-polyurethane hybrid sealant. But you
can use whichever bathroom silicone in principle.
Terostat MS 930 is a low strengh sealant, thats why it
is better. You will need a medical syringe which you 
fill with this stuff (not fully, you wont need much).
Also get an injection needle of the thicker type and
shorten it, unless you can get professional dispensing
needles like these:

https://store.sra-solder.com/shopimages/sections/thumbnails/tips.jpg

Now you have your syringe with the needle and the
sealant paste inside. Unfortunately I did not make
pictures during the process, but I just made a few of
the syringe which I am attaching.

Take your XB apart. Do the regapping on the
reedplates.

Apply a thin film of silicone grease onto the comb
mating surfaces to prevent the sealant sticking to it
too much (so you can take it apart next time again).
Now get your syringe and apply a thin bead of sealant
onto the thin chamber walls and all around. Dont
forget to insert the mouthpiece nuts. Put the two
comb-halves together. Apply a bead onto the mouthpiece
(leave some silicone grease on it coming from Hohner,
the white stuff). Assemble the mouthpiece. 

You will need some manual skills to apply the thin
bead of sealant onto the thin chamber walls. Dont use
too much. I used a black sealant because the comb is
black, but a transparent one will also look fine. 

Now apply some silicone grease onto the reedplate
inner surfaces and onto the comb outer surfaces (where
they will touch each other). Then apply a thin bead of
sealant again onto the comb chamber walls and all
around. Put the reedplates carefully onto the comb so
that you dont smear the sealant all over the place and
you dont get any on the reeds.
It is important to use silicone grease wherever a part
is in contact with the sealant, so that your harp does
not stick together forever.

Bolt it together. The stuff cures by air moisture
slowly (like silicone polymers in general). Leave it
for a day and hopefully next day you will be
surprised.
You get a fully airtight, very responsive, very loud
XB40. If you don't, you either have not done the
sealing well, or your harp was good anyway (which was
not the case in all 3 pieces of mine and I believe
this is a general design problem with the XB not a
general assembly problem). After the procedure, the
XB40 is a VERY GOOD harmonica indeed! This is
certainly my private opinion which I am sharing on the
list in case anybody else can benefit from it. 


Zombor


--- Winslow Yerxa <winslowyerxa@xxxxxxxxx> wrote:

> I never felt the need to seal. After about two years
> I started
> tinkering with gaps and embossing and managed to
> effect some
> incremental improvements - nothing earthshaking.
> 
> My chief complaint is that sometimes when attacked
> hard the reeds buzz
> as if they're hitting something - possibly the
> covers abut also
> possibly the internal "floor" of the chamber. I've
> been meaning to
> scrape a little out of the chamber floor to give the
> reeds more
> clearance and see if that helps.
> 
> But I'm curious about the sealing effort. You
> haven't described what
> you actually do to make the instrument more
> airtight. If an improvement
> is worth doing and talking about (50% sounds
> worthwhile), I'd like to
> at least try it. Could you supply details, please?
> 
> Thanks.
> 
> Winslow
> 
> --- Zombor Kovacs <zrkovacs@xxxxxxxxx> wrote:
> 
> > Really??? Then non of you have tried to seal the
> combs
> > and reedplates and adjusted responder reed gaps.
> If
> > you  are saying they are good out of the box, just
> > give it a go. You will be surprised how much
> better
> > they get after a full seal and gap adjustment.
> Mine
> > became at least 50% better.
> > Out of the box it is leaking everywhere,
> especially
> > between the individual chambers. No wonder,
> because it
> > has only got bolts at the edges, and the chamber
> > separating walls are so thin. So I strongly
> recommend
> > that you try what I did!
> > 
> > Zombor
> > 
> > 
> > --- Winslow Yerxa <winslowyerxa@xxxxxxxxx> wrote:
> > 
> > > I have to agree with Rick. I have been playing
> XBs
> > > in Low D, G, and A
> > > for several years now. They have always been
> > > airtight without tweaking,
> > > and are loud and flexible for fiddle tunes. They
> are
> > > also extremely
> > > durable.
> > > 
> > > Winslow
> > > 
> > > --- Rick Dempster <rick.dempster@xxxxxxxxxxx>
> wrote:
> > > 
> > > > Really? What's wrong with them? I've had a C
> for
> > > about two years and
> > > > an
> > > > A for one. I think they're a wonderful
> instrument
> > > (apart from the
> > > > squeeky top end,with which I'm gradually
> coming to
> > > terms - sort of)
> > > > and
> > > > well worth the $$.
> > > > RD
> > > > 
> > > > >>> Zombor Kovacs <zrkovacs@xxxxxxxxx>
> 25/03/2007
> > > 6:05:12 >>>
> > > > By the way. I have just bought two XB40-s.
> They
> > > are
> > > > still plain crap out of the box. But after
> sealing
> > > > them fully they are great, apart from hole nr
> 10.
> > > THey
> > > > are not worth the price, but cool to practice
> and
> > > do
> > > > funny things with :-)
> > > > 
> > > > 
> > > >  
> > > >
> > >
> >
>
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