Re: [Harp-L]Comb test

[David Payne <dave@xxxxxxxxxxxxxxxxxxxxxx>]

The problem is, Vern, I believe you're mostly right. But we could do brass vs. wood next time I am able to get to a Spah where we could do it and I'd like to draw in my other four most-trusted ears as well, if they'd be willing (Jason Ricci and Wally Peterman).  You could give the $1,000 to Young Harmonica Allstars International or keep it, whatever. I, on the other hand, do not have $1,000 to put up, nor am I really concerned about that money. I only want to better understand how the harmonica works.
I have thought for years about this and I have been in varying degrees on both sides of this fence. I was positive that comb material had no effect on tone, Vern had convinced me of this. I was positive until the 2010 SPAH test. The brass comb seemed so vibrant to me and I could usually hear it. I was sitting back far enough where I couldn't see what was what and I made it a point not to look. What I heard made me rethink everything. 
I've done quite a few experiments. Some of those experiments indicate Vern is right. Some of those experiments indicate that Vern is not. 
My current hypothesis is that we have all been wrong to some degree and that Vern has been more right than most, but not entirely right. 

This is mostly for those following along. I would never insult Vern's intelligence, which I respect by going into some of these elementary details, and I'm sure Vern will think I'm full of it anyway, lol.:
 
The most basic thing that affects tone is the reed itself and the resonant chamber. How it is profiled - the varying thicknesses along its length - and how the air flows to the reed. I was fortunate enough to soak up a lot of Harrison Harmonicas' work on studying the affect of air flow to the reed on tone. The resonant chamber, of course, is the human innards. 
Here is an explanation of air flow: 
http://www.elkriverharmonicas.com/harp_school/1890s


Most people think of a difference in tones as they would think of the tonal properties of materials on instruments such as guitars or mandolins. The problem being that those woods serve as resonant things. Combs don't work that way. 

Jacob Hohner had a theory back in the 1890s that coverplate resonance had an affect on tone. That was the whole point of the Mouse Ear Marine Band, to lift the coverplates up from the reedplate and minimize contact with the reedplate, so the coverplate would be more free to vibrate. The sound from a guitar, for instance, comes from the vibrating top, not the "sound hole." the sound hole is actually there to relieve air pressure inside - even medieval builders understood that. When I wrote the page linked to above, I thought Richard Seydel's side-vent air flow concept was more valid than Jacob Hohner's coverplate resonance concept, but since have changed my mind to believe they are both equally-valid concepts. Jacob Hohner's vibrating coverplate concept isn't very well accepted, the argument being how is this possible when your hands are on the coverplate. How can it vibrate. 
 
So I did a couple of experiments. First experiment I thought would totally debunk Jacob Hohner. I tried playing a single note, then laying my index finger across the coverplate. I expected to hear nothing, but I was shocked to hear a definite change in tone. As my finger was placed on the top coverplate (as I blew a note), there was a noticeable decrease in treble overtones. So, my next question was if the finger is on the coverplate, is there still sound vibration traveling in the coverplate? 
   I sought to answer this on my kitchen table, which is fairly small. I placed my ear on table and then rapped my knuckles on the other side and listened to how that sounded. Then, I laid my body across the table (I'm 6 feet two inches tall, 240 pounds). This seemed to me like a good scale test. I did the same thing while laying across the table and noticed how the rapping sounded. It was not dampened. 

So, I thought, if the sound can still travel through the material when a weight is pressed upon it, can it still have an affect on tone - then I realized that you can only cover less than 50 % of a coverplates' surface. The inside surface is always uncovered and free. 

That's where I am now in my study of this. My next test will be to study the effect of the opposite-side coverplate on tone. Vibrations have to get to that coverplate somehow. I didn't see any of those combs. If the plastic combs were solid plastic - as opposed to the spinly recessed reedplate plastic combs - I think that would account for why I heard no difference between them. But, I'm still working on connecting all these dots. Maybe someday, I'll figure it out. 

David Payne
www.elkriverharmonicas.com


Elk River Harmonicas Forum now available via Iphone app, www.elkriverharmonicas.com/forum


________________________________
 From: Vern <jevern@xxxxxxx>
To: David Payne <dave@xxxxxxxxxxxxxxxxxxxxxx> 
Cc: Harp L Harp L <harp-l@xxxxxxxxxx> 
Sent: Saturday, October 27, 2012 8:08 PM
Subject: Re: [Harp-L]Comb test
 



On Oct 27, 2012, at 11:12 AM, David Payne wrote:

Icould get the brass about 90 or 95 percent of the time............... because the brass comb sounded really obvious to me. 
>comb 
IF you can distinguish between brass and wood combs under similarly controlled conditions, then you can win my $1000 wager.  Not only that, but you can have the pleasure of forcing me to admit on Harp-l that I have been wrong for 15 years and that the materials effect is not a just cherished myth.

Vern