Re: [Harp-L] widening out/opening up the backs of harps

[Randy Redington <rwredington@xxxxxxxxx>]

Maybe so so...
But I still enjoy doing it. For some folks it may seem like a waste of
time, but for me... its fun.
BTW, I play sp20s.
I don't cut my cover plates, I just bend them in.
And I don't bother with side vents like you find on the manji and
crossover.
I don't think the volume is affected but I do believe it affects the timbre
of the sound.
---
Randy Redington
Surrendered...

*Sent from my Verizon Wireless 4G LTE smartphone


On Mar 9, 2016 5:57 AM, "Rick Dempster" <rickdempster33@xxxxxxxxx> wrote:

> I agree, no difference worth noticing; but what, for example, Joe Spiers
> does makes the plates stronger,
> so my 'pocket' harp does much better with this particular mod.
> RD
>
> On 9 March 2016 at 08:33, Vern <jevern@xxxxxxx> wrote:
>
> > Widening of the backs of harmonicas will have little effect on the sound
> > for several reasons.
> >
> > Diffraction is the tendency of sound waves to widen out when passing
> > through an opening smaller than the wavelength.  This means that the
> shape
> > and size of the back opening will not affect the direction of the sound.
> > See
> >
> http://www.ck12.org/user:a2VsbGV5dEB1c2QyMDQubmV0/book/Waves-and-their-Interactions-with-Matter/section/1.1/
> >
> > The area of the back opening is huge with respect to the area of the reed
> > slot.  As a consequence almost all of the pressure drop occurs across the
> > slot. This means that constriction of air flow by the back opening is
> > minuscule.
> >
> > The logarithmic response of the human ear makes small differences in
> > loudness imperceptible.
> >
> > I have covered more than half of the back opening of a harmonica and have
> > not been able to measure any difference in loudness on a meter.
> >
> > Bottom lineâRobert is correct, flaring the back opening is a waste of
> > effort.
> >
> > Vern
> >
> >
> > > On Mar 7, 2016, at 10:09 AM, Robert Hale <robert@xxxxxxxxxxxxxx>
> wrote:
> > >
> > > On Mon, Mar 7, 2016 at 9:45 AM, Peter Beck <kpfbeck@xxxxxxxxx> wrote:
> > >
> > >> widened out the backs of a bunch of Special 20s
> > >
> > >
> > > âI haven't found the result to be worth the work to open the backs of
> > harp
> > > covers.
> > > I consider gapping, embossing, and arcing more worthwhile than flared
> > > covers.
> > >
> > > NEAR
> > > There are some variations of sound heard by the player in close
> proximity
> > > to the reeds. Since it is a personal experience, one may choose to
> pursue
> > > the modification.
> > >
> > > FAR
> > > I don't think the audience, and most players, can distinguish open to
> > > closed back harp on stage.
> > >
> > > To evaluate what a microphone picks up, and delivers to an audience,
> > either
> > > live thru the PA or recorded medium, we would need to test only ONE
> > > variable: the open to closed back of ONE model harp.Other variables
> among
> > > harps are reed composition / design, comb, choice of mic, and EQ in the
> > > chain. Again, if the A/B difference is significant to the player it can
> > be
> > > done.
> > >
> > > So I place the topic down the list of important activities. Best use of
> > my
> > > time is practice and performance.
> > >
> > > Robert Hale
> > > Serious Honkage in Arizona
> > > youtube.com/DUKEofWAIL
> > > DUKEofWAIL.com
> >
> >
> >
> >
>