Examples

Analysed examples

Classical

Spectrum tap tone classical

f air = 110 Hz

The peak of the air resonance stands out which is consistent with the relative strong lows of this instrument.

 OM

Spectrum tap tone OM

109 (Air), 226 (Top)

The top and air resonance frequencies are coupled which is good. The back is pretty stiff and not very active. This explains why the air resonance frequency is higher than that of the OMC model below.

OMC

Spectrum tap tone OM Cutaway

Main resonance frequencies: 101(Air), 201(Back), 210(Top)

Analysing the spectrum shows that the main resonance frequency of the top is double the value of the air resonance frequency plus a semitone and the back has a peak resonance frequency a semitone less than the top. This is good. These values were created by measuring frequencies during the building process and changing the weight of the bracing before mounting the back of the guitar. The result is a coupling between the various resonance frequencies. The spectrum shows a balanced tone because dominant peaks have been avoided. The relative lighter top results in more response for higher frequencies and together with the loser back a lower air resonance frequency.

Selmer Maccaferri

Main resonance frequencies: 254(Top), 93(Air), 215, 138, (1397)

This picture explains the very different character of a gypsy jazz guitar. A low air resonance frequency of 93Hz  is related to the small oval hole and a lot of response at the higher end of the spectrum is because of the light dome shaped top.

(Note: Scales are different from previous pictures)

Ukulele