end plate designs and sound production

[david_boveri]

i am interested in designing my own end plates. whether or not i will depends on several factors, but one thing i am wondering about is how does end plate design affect the tonality of the instrument?

 

i understand that the resonance of the wood panels on the end is not VERY clearly understood, but i was wondering about it insofar as anyone has any experience or has read research.

 

i read once that the percentage of wood vs. open space is important. is that more important than where the wood is?

 

any makers out there: have you ever swapped end plates on the same instrument and noticed a large difference in tone quality?

 

my main concern is how much the endplate design will end up affecting the sound of the instrument, and if it could affect it in a negative way.

[Chris Ghent]

i read once that the percentage of wood vs. open space is important. is that more important than where the wood is?

Both are important. Look at this end... http://www.hobgoblin.com/local/shbigpic.php?Code=48H1263 Notice how the holes are positioned so the treble reeds are closer to holes than the bass reeds. And the small individual size of the holes (as distinct from the overall % of transparency), is that an accident? Not likely! There are no accidents in an instrument of this quality.

any makers out there: have you ever swapped end plates on the same instrument and noticed a large difference in tone quality?

I made three ends to fit one instrument from the same wood with differing transparency, ranging from very open to very closed. The difference in tone was very marked subjectively, and obvious also in harmonic displays.

my main concern is how much the endplate design will end up affecting the sound of the instrument, and if it could affect it in a negative way.

The results could not be graded 'good' or 'bad', just different. The more closed end could be described as more resonant (resonance: the prolongation of sound by reflection; reverberation).

 

What follows is conjecture. If you have had the experience of playing in a large reverberant space (ie. Juliette Daum) you will have discovered in order to make use of the reverb you need to play slowly, and full chords work well. This is because reverb is calulated in time and large spaces mean a longer delay. If you change a note to a semitone higher before the reflection returns you will essentially have a dischord. The delay inside a relatively tiny chamber such as an end box is shorter so less likely to be an issue but at very high playing speeds in a very closed end you could be running notes over the top of the tail of earlier notes. Resorting to some relatively simple maths might help work this out but without knowing how many times the sound bounces it is hard to assess.

 

Consequently if you were intending to play a lot of full chorded slower notes the less transparent and therefore resonant end might suit you. A string of fast single notes might be better in an open design. And of course there are lots of positions in the middle..!

 

Hope this helps

 

Chris

[chris]

Hi

perhaps what's needed is an adjustable vent system whereby the size of the apertures in the fret board can be altered-possibly a sliding/rotating inner fret board that when fully open would match the largest fret appertures but when rotated would cover, to a greater or lesser degree, the main fret appertures.

chris (I know what I mean but can't explain it very well )