Re: [Harp-L] triple vs quadruple reed harps

[Winslow Yerxa <winslowyerxa@xxxxxxxxx>]

In addition to Richard Sleigh's very interesting speculation, I have an additional idea about why the XB-40 reeds seems to stand up well to hard playing.

It's the shock absorber theory.

In a dual-reed system, such as in a standard diatonic harmonica, both a blow reed and a draw reed receive air whenever a note is played. By contrast, in a fully valved harmonica, only one reed receives air.

You can play stronger attacks on an unvalved dual reed instrument than on a fully valved instrument. Hence the common problem of a diatonic harmonica player picking up a chromatic harmonica for the first time and finding that the notes blank out and refuse to speak - each isolated reed is getting more energy than it can handle unless the player learns to moderate his attacks.

Iin a dual reed system, excessive attack on a blow reed is partially absorbed by the draw reed, and vice versa. However, it's still possible to give a reed more energy than it can dissipate through vibration within its stress limits, and the reeds do not respond equally, as one bends down in pitch and the other doesn't.

In a quadruple reed system such as the XB-40, all main notes bend down and all have a responder reed to absorb excess energy. Thus stress is cut in half as its distribution is doubled.

It may be that the internal air direction system and larger cavities also play a part as Richard posits, as the XB-40 is definitely much louder than both a standard diatonic and the SUB 30.

Winslow

Winslow Yerxa
Author, Harmonica For Dummies, ISBN 978-0-470-33729-5
            Harmonica Basics For Dummies, ASIN B005KIYPFS
            Blues Harmonica For Dummies, ISBN 978-1-1182-5269-7
Resident Harmonica Expert, bluesharmonica.com
Instructor, Jazzschool for Music Study and Performance