Re: [Harp-L] Comb Design

[Derwood <derwood.blues@xxxxxxxxx>]

Vern,

I make no argument that the sound projected to the audience is effected in
any discernible way by the material of the comb. What I notice is that I
like my harmonicas with solid combs better. It is hard to tell if it is the
noticeable weight difference (it feels more sturdy, better) or the effect on
the mass of the harmonica that is in the transmission path of the sound
waves through my body.

A question about the SPAH2010 experiment: Was this the one where mass was
added to the combs so that the player could not distinguish the material by
weight of the harmonica? If so then it would not be a good experiment to
show the invalidity of my theory on the sound transmission through the
body.

Derwood

On Sat, May 21, 2011 at 1:38 AM, Vern <jevern@xxxxxxx> wrote:

> At SPAH2010, a half-dozen virtuoso harp players tried to discriminate
> between diatonic combs of different materials...brass, wood, plastic,
> bamboo, etc. by playing them.  The tests started with the players
> blindfolded, but the blindfolds were abandoned early in the session.
> However, combs of various materials were installed in the same harmonica out
> of their sight and their exposed surfaces were painted the same color. Some
> could not detect any reportable differences.  Others reported differences
> for successive playings of the same comb.  No player was more accurate than
> a person guessing would be.
>
> Because the comb plays no part in the generation or transmission of
> harmonica sound, the material of which it is made does not perceptibly
> affect the tone or loudness.  This statement is abundantly supported by
> acoustic theory and by three empirical comparisons done under controlled
> conditions at SPAH97, Buckeye98, and SPAH2010.
>
> Joe is correct that the hollows in injection-molded plastic combs are there
> to avoid warping while cooling.  However, plastic combs can be molded by
> using urethane plastic that hardens at room temperature and by CNC
> machining.  These designs more closely resemble the familiar shapes of
> wooden combs.
>
> Vern
>
> On May 20, 2011, at 8:09 PM, Joe Leone wrote:
>
> >
> > On May 20, 2011, at 11:05 AM, Derwood wrote:
> >
> >> Let me start by saying my opinion of the comb tone debate is that the
> comb
> >> material effects the vibrations that the player experiences and has the
> most
> >> effect on how the sound feels to the player.
> >
> > I feel the same way.
> >
> >> I tend to prefer to play more solid combs. So that leads to my question,
> >
> > I prefer my solid bronze 270. Most of my other chromatic combs are still
> wood. (diatonics all spl-20s)
> >>
> >> Why do manufacturers make plastic combs with hollow sections.
> >
> > When molding plastic, the cooling would be different for thinner sections
> than it is for thicker sections. This would cause shrinking that would pull
> the comb out of shape. So, the moldings have to be designed so that no cross
> section is thicker than the webs between the reed chambers (generally the
> thinnest part). That way the entire comb would cool evenly and hence keep
> it's shape. A metal comb is usually machined and has no such limitation.
> However MY metal comb does have areas cut out in an effort to keep the
> weight down. The voids are also a handy place to stash gems.
> >
> >> Is it for some perceived tonal effect,
> >
> > No
> >
> >> to reduce weight
> >
> > No
> >
> >> or is it to save money on plastic
> >> material?
> >
> > No, the plastic is only worth a penny and the mold for those channels is
> FAR more expensive than without the channels.
> >>
> >> Since I seem (have not yet done a double blind) to like the vibration of
> >> solid wood and aluminum combs, I wounder if a solid plastic comb would
> be
> >> more pleasing to me than the standard "thinline" plastic combs.
> >
> > I don't know but the Amadeus chromatic has a fairly solid comb (lucite)
> and I love the sound. For diatonics, I don't think it would matter. They are
> already so 'vocal' that I don't think they can be improved upon.
> >>
> >> Any thoughts? Any real knowledge of manufacturers motives?
> >
> > Motives are: Plastic is more stable than wood. Metal is too heavy for
> some applications. Moulding (once a mold is made) is cheaper than milling
> plastic.
> > smo-joe
> >
> >
> >>
> >> Thanks,
> >>
> >> Derwood
> >
> >
>
>
>