Re: [Harp-L] Chromatic cover lids modification

["hazcon" <hazcon@xxxxxxxxxx>]

Vern to me you are the James Randi of the Harmonica world....and that is a 
compliment..

Aside from the physics involved........I would also wonder why anyone would 
want to open the backs of a harmonica,especially if they were playing 
amplified Blues Harp.
         There has been A lot of discussion over the years about amplified 
tone and one of the crucial things mentioned is the complete enclosure of 
the harp to get that 'overdriven ' sound.David Barrett has a whole U Tube 
series on how to 'cup' the harp and mike to make it airtight.
         Opening up the covers I think would make that airtight seal even 
harder to achieve.
Rick
in NZ
----- Original Message ----- 
From: "Vern" <jevern@xxxxxxx>
To: "Denny Noreikas" <harpmessin@xxxxxxxxxx>
Cc: "Harp- L" <harp-l@xxxxxxxxxx>
Sent: Friday, January 14, 2011 18:32
Subject: Re: [Harp-L] Chromatic cover lids modification


> If many buyers think, as you do, that openings in back of a harmonica have 
> a perceptible effect on loudness, the manufacturers will cater to those 
> beliefs, whether or not they are true.  Hohner has actually claimed that 
> different  types of wood used for combs produce perceptible differences in 
> tone!  Manufacturer's, in an effort to differentiate their harmonicas from 
> those of the competitors, will often make claims that are not fully 
> justified by acoustics.  A common ploy is to exaggerate some minuscule 
> effect.
>
> Hearing is a very subjective sense.  Listeners will report hearing what 
> they expect to hear.  It requires testing under very carefully controlled 
> conditions to avoid these subjective effects. Knowing whether the opening 
> in back is larger or smaller will affect what you think you hear.
>
> Human hearing is logarithmic.  Sound level is measured in decibels.  An 
> agreement is made on a reference level of sound pressure that is barely 
> perceptible to the "average" person.  Then the db level of a sound is ten 
> times the logarithm of the ratio of the sound pressure to that reference. 
> A human can barely detect a sound level change of 3 db where the level is 
> suddenly changed....as in an A/B test of hi-fi speakers.   Yet a 3 db 
> increase is a doubling of the sound pressure!   If you listen to a sound 
> in a room, then go to lunch and come back to the room to hear the same 
> sound at a different level, it takes a very much larger difference to be 
> perceptible.
>
> Any slight change in the opening will have only a small % change in the 
> level and will be imperceptible to your ear.
>
> However, it is your harmonica and your ears.  If you do not find my 
> arguments persuasive and you want to cut or bend open those covers and 
> rejoice at the increase loudness, have at it.
>
> Vern
>
> On Jan 13, 2011, at 6:19 PM, Denny Noreikas wrote:
>
> > Vern,
> >
> > That is interesting. I wonder why the new trend in diatonic harmonicas is 
> > a more
> > open back? They do seem louder to me but are also more susceptible to 
> > denting.
> > I'm confused.
> >
> > Denny
> >
> >
> > On Jan 13, 2011, at 7:03 PM, Vern wrote:
> >
> > > The curling in of the cover plates does not perceptibly suppress the 
> > > sound.  I once blocked off more than half of the opening in the back of 
> > > a harp with an aluminum plate.  There was no perceptible difference in 
> > > the sound as measured on my sound-level meter.   When you cup a harp in 
> > > your hands, there is hardly any effect until your hands are almost 
> > > closed.
> > >
> > > Opening up the Velvet Voice covers would be a waste of your time.
> > >
> > > Vern
> > >
> > > On Jan 12, 2011, at 5:27 PM, Denny Noreikas wrote:
> > >
> > > > All this recent talk about which Chromatics to buy got me thinking 
> > > > about trying the
> > > > Chromatic again for playing Blues. I have 2 key of C's, a Hohner CX-12 
> > > > and a Hering
> > > > Velvet Voice 48. The CX-12 is too shrill for me compared to the Velvet 
> > > > Voice. I like the
> > > > rich smooth sound of the Velvet Voice. However, the top and bottom 
> > > > cover plates on the
> > > > Velvet Voice curled around toward the comb in the back of the harp 
> > > > which narrows the
> > > > back opening suppressing the sound. I am sure this is by design.
> > > >
> > > > The CX-12 has a very large opening in the back. Can the cover plates on 
> > > > the Velvet
> > > > Voice be filed down with a Dremel tool or similar device to open up the 
> > > > back? I am not
> > > > a customizer nor do I want to screw-up a perfectly good harp.
> > > >
> > > > Any help would be appreciated.
> > > >
> > > > Denny