Needle depth on a 5A soundbox

[Phono48]

You should try them soundboxes with triangular bamboo needles... They're great, specially with soft recordings, piano and violin, chamber music and the like, also Opera electrics.
For most other records, soft tone steel needles are also great, delivering powerful volume with no shrill...

I don't know why, but over the years, I've tried many fibre needles, (are they the same as bamboo?) and I just can't get on with them. They always seem to run out of steam about three quarters of the way through a record. Maybe because the majority of my records are in good, but not absolutely mint condition? I do always use soft tone needles, purely out of respect for the discs, but even they can vary considerably in quality.

Barry