Have you weighed tailpieces before of various woods? Many basses over 100 years old with original tailpieces are stained boxwood or maple stained black and not ebony. With the quiver added, (weight them!), that ads 4-5 ounces. I almost always use a quiver and even pack my bass with the bow in the quiver. I have very very expensive basses and bows as well. These great old expensive basses are not effected much at all with a quiver. I put them on tight to the TP as seen on some of my pages.
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The first bass I have now as my personal instrument. All the others were at one time my main bass (except the Malvolti and Prescott) have have been sold. Bow quivers had little or no effect other than smoothing out the high end of the bass on some instruments. Your body touching the bass is the biggest mute, not the 5 ounce quiver.