Needle can make more difference that you might think.

[CarlosV]

The other reason may be that soft tone needles don't change the volume of sound in strict terms, but they act by altering the frequency response preminently (to the best of my knowledge, this point was first discovered and explained by Paul C. Edie on his website The Victor Victrola Page).

This is a very interesting article, Marco, and indeed the first time I see a physical explanation for the
engineering of the needles. The author applied good engineering standards to the experiment, including creating a model and verifying its credibility by experimentation. In essence it demonstrates that the needle acts as a filter, which is evident in the case of non-metallic needles, but not so when comparing soft and loud tone metallic needles. Thanks for including the link.

[Menophanes]

I too would like to thank Marco Gilardetti for the reference to Paul Edie's article. I have often wondered why there should be a correlation between the thickness of the needle and the 'loudness' (to use the old simplistic perception) of the record; here at last is a properly reasoned and exemplified discussion on the subject.

I also remember (from the distant past, since I have not used any loud-tone needles for about forty years) that the thickest needles seemed to exaggerate the surface noise to an extent that was out of all proportion to the (apparent) increase in the volume of the actual music. This is only a subjective observation, of course, but as far as it goes it would appear to be consistent with Mr. Edie's findings, since there is certainly a large high-frequency component in the surface noise.

I may add that I have long been accustomed to use 'Songster Pick-up' needles (made by the English firm of J. W. Stead) on records of all periods from 1896 to the 1950s. I do not know if these are the '15-side' needles mentioned by several previous contributors, but that is the number at which the Songster needles are rated. I used to find that ordinary single-play needles (as available back in the 1970s; I cannot speak of anything on the market today) would quite often damage the opening grooves of the record (presumably because of some roughness in the finish of the points), whereas the pick-up needles rarely if ever do this; in other words, the pick-up needles appear to have been more precisely quality-controlled in manufacture. This gave me confidence in the pick-up needles, and in consequence I have used practically nothing else for more than half my life so far. But, once again, this is only a personal impression whose validity I cannot prove. The pick-up needles are similar to ordinary medium-tone needles in profile and acoustic performance.

Oliver Mundy.