RE: [Harp-L] An Over-Blurring Of Over-Bends And Over-Blows

["Bradford Trainham" <bradford.trainham@xxxxxxxxxxxxx>]

Thanks for the responses.
I think... What frightens me most at this point... Is that I actually
understood most of what David and John said... 
A year ago, I would have never imagined I'd be.. In this deep.

Thanks again,
Brad Trainham
 

-----Original Message-----
From: john [mailto:jjthaden@xxxxxxxxx] 
Sent: Sunday, August 17, 2008 2:37 PM
To: bradford.trainham@xxxxxxxxxxxxx; 'David Payne'; 'Harp L Harp L'
Subject: Re: [Harp-L] An Over-Blurring Of Over-Bends And Over-Blows

Overblows and unvalved blow bends share something huge:  they both recruit
the draw reed, causing it to be sounded by blown air -- by an air stream
flowing in the opposite direction from the  usual.  In musicological terms,
it is made to behave as an opening free reed (by pressure that would
initially open the gap further.  Harp reeds normally behave as closing free
reeds.).  Opening reed behavior occurs even in the absence of a second reed
in a hole and it causes the reed to vibrate at a higher pitch than as a
closing reed -- anywhere from a rather flat half-step higher, up to probably
more than a major third higher, depending on embouchure.  

So what does distinguish overblows from unvalved blow bends?  It's the
contribution of the normal blow reed.  As a player adjusts embouchure and
pressure, a blow reed tuned lower than the draw reed (Richter holes 1-6) may
bend down a bit, but also will readily choke off, partially blocking its
slot.  This allows pressure to increase into the slightly higher range that
favors opening-reed vibration of the draw reed:  the overblow.

A blow reed tuned higher than the draw reed (Richter holes 7-10 plus MB 365
holes 11-14) also may bend down a bit under player control, but here, if it
does, its new pitch is liable to be supported by vibrations of the
lower-pitched draw reed as it starts its opening-reed behavior.The two reeds
are able to match their vibration rates, to resonate together.  This can
happen over a wide range of pitches, from the normal blow-reed pitch, down
to the lowest opening-reed pitch of the draw reed (a flat half-step above
the normal draw-reed pitch). The smoothly controllable result is what we
call bending.

If the blow reeds in a chamber is tuned considerably higher than the draw
reed, then the bent blow reed pitch may not be able to be matched by the
draw reed, regardless of resonance.  In that case, the blow reed will be
more inclined to choke off completely.  
The note will then jump immediately down to the preferred pitch of the draw
reed (while vibrating in opening-reed mode).  Some of you may have
experienced this on the 10th hole of a 10-hole diatonic, which has a
minor-third interval, but it is far more evident on holes 11-14 of the
Marine Band 365, where intervals are even wider. The behavior of these 'blow
bends' can be a lot more "overblow-like" than bend-like: they "pop" in
instead of slide in.

Lots of harp performance issues become pretty clear if you keep in mind the
two behaviors of isolated harmonica reeds: as closing and opening free
reeds.  If you haven't tried, I think its pretty interesting to tape over
one or the other of the two reeds in various holes and see what sounds you
can produce with the isolated reed (and under what conditions it chokes
off).  This is a quick way to learn over-blowing and overdrawing.

Regards,
John Thaden    



======= At 2008-08-16, 16:39:11 Brad Trainham wrote: =======
>So then..., it's really a curiosity of the architecture of that harp 
>which makes the blow-bends yield the same result as what we'd expect 
>from over-blows?
> (At this point, a "Huh???" response would be entirely appropriate and 
>wouldn't offend me in the least.)

>
> On Saturday, August 16, 15:50, David Payne wrote
>>  The E blow is the higher one, right? Assuming that, what you're 
>> doing isn't an overblow, it's a blow bend like you said. The limit of 
>> the bend is a half-step higher than the lower, opposing reed. In this 
>> case, you are blow bending to it's natural limit, a half step higher 
>> than the B reed, which is this C.

>> Prior to that, Brad wrote:
>>>  On A Hohner Marine-Band 365, in the key of c..., we find holes 11 
>>> through 14 giving us...
>>> Hole 11 - e-blow b-draw
>>> Hole 12 - g-blow d-draw
>>> Hole 13 c-blow f-draw
>>> And hole 14 - e-blow a-draw...
>>>
>>> My question... When I blow-bend hole 11, I get... 
>>> Consistently a c, which is a half-step higher than 
>>> the draw pitch.   This would meet the requirements 
>>> for the "over-blow' rule, but surely, this isn't a true over-blow? I 
>>> get the same results with holes 12 through
>>> 14 on this harp, that is, what we would expect from an over-blow, a 
>>> pitch a half-step higher than the draw.