Re: [Harp-L] Life of narrow reeds.

[diachrome@xxxxxxxxxxx]

Vern, 
Probably most of my customer base, as well as other chromatic techs, is on Slidemeister rather then harpl. 

You and Winslow might want to pose a question to a broader chromatic audience that has their chromatics serviced on a regular basis. 
The results could be mentioned here. I don't want to mention any customers by name to point out their problems. It's best they come forward on their own. 

I have started a data base detailing what and when I do to someone's chromatic over the life of the harp but I haven't listed if it's a newer or older model. I guess I'll start doing that 
so I have complete data to back up my claims. 

I cringe every time I see a X stamped on a reed plate for repair. I know it will add an extra 1/2 hour or more to the job of replacing a reed. 

The only difference I can find in the newer reeds is that I can't retune them as far up or down as I use to. I'm finding the reeds start to flake or fold shortly after retuning a semitone. 
This is on both the wide and narrow versions of the new reeds. 


----- Original Message -----

From: "Vern" <jevern@xxxxxxx> 
To: diachrome@xxxxxxxxxxx 
Cc: harp-l@xxxxxxxxxx 
Sent: Tuesday, November 12, 2013 6:00:42 PM 
Subject: Re: [Harp-L] Life of narrow reeds. 

Theoretically, the stresses in a reed are not a function of width. Thus the stresses in a narrow reed should be no more than those in a wider one. 

Do the following mental experiment: 

Imagine two identical side-by-side reeds vibrating at the same frequency, phase, and amplitude. Viewed from the side, they would appear to be one reed. Then join them into one reed of twice the width. There are no forces between the halves either before or after they are joined. This is why you can trim a reed to a narrower width without major changes in pitch. 

Has Hohner changed the design of the reeds in other ways beside just making them narrower? If this is the source of the problem, then your trimmed reeds should live as long as the older wide reeds. 

It is possible that some secondary effect accounts for the observed shorter life of narrower reeds. However, it is not predicted by the formulas for bending stress. The expression for metal stress in a reed does not include a width variable. 

I can speculate about why they made the change. They thought that the smaller orifice for air flow would make it easier to form a resonant embouchure and make the high notes easier to play. Maybe Rick would know. 

Whatever the reasons, they created a major problem for reed-replacing technicians. 

Vern 


> Mike 
> www.harmonicarepair.com 
>