[GP49000]

SP25 Mk IV differed at first from the Mk III only in trim. As the supply of Mk III tonearms dwindled, a new headshell design, rectangular in shape with a waffle pattern on top, was introduced. It still accepted the same C2 cartridge clip and was functionally identical. The arm was not calibrated for antiskating or stylus force below two grams, which was the practical lower limit for the Autoslim chassis. The SP25 Mk IV was the last in the SP25 line to have idler-wheel drive, and the last to operate at 78rpm.

SP25 Mk V had belt drive, using the same parts as the former higher-priced 125SB. It was the first SP25 to operate at only two speeds, 33 and 45. It also had a new, S-shaped tonearm that shared the C5 cartridge clip with other models such as the 125SB, the 990B record changer and the DD75 direct-drive turntable. Its counterweight no longer had a locking screw as did those on earlier SP25s, but was on a rubber mounting that slid along the rear tonearm shaft for adjustment, being retained by friction. It retained the same dial-type stylus force adjuster as had been used since the SP25 Mk II and 60 Mk II.

SP25 Mk IV, early version.
SP25 Mk IV tonearm, early version
SP25 Mk IV, late version.
SP25 Mk V, note S-shaped tonearm
SP25 Mk V, tonearm detail showing new counterweight.