Re: [Harp-L] Comb Design

[Joe Leone <3n037@xxxxxxxxxxx>]

On May 21, 2011, at 1:38 AM, Vern 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.

I know Vern. We were just talking about how they FEEL in the hands. ....stay calm big stallion   lol No one is resurrecting any dead Cavallos. 
> 
> 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.

Yeah. we weren't talking about that. Again...key word here: "feel". ....not the same thing. 
>  
> Joe is correct that the hollows in injection-molded plastic combs are there to avoid warping while cooling.

That's what 'I' was referring to. I didn't include machined combs in this sentence. Why? Because there are comparatively few machined combs out there, (as compared to moulded). The moulded combs would be the ones that had a shrinking issue. You are correct about the machined combs. I covered that when I mentioned that moulding plastic (once the mould is made) is cheaper than milling. The Amadeus has a milled comb. Other than that, the old Farrell comb comes to mind. I don't know of too many other chromatic combs that are milled. There are probably a number of diatonic combs that are milled from plastic. And a TON milled from various woods.   

>  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.

Yes, sorry for the confusion. He was asking "Why the cavities", so I was answering PREsuming we were talking moulded plastics. (Thought I would say ASSume..didn't ya). 
smokey apologizes for any misconceptions as to his wording.   
> 
> 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
>> 
>> 
> 
>