Hydraulic Reference Turntable
As the name proclaims, this was one of the first reference turntables (1963) with a pitch control as additional feature.
First by means of applied friction on top of the strobewheel, later through an under the platter affixed bassin filled with a thick viscose liquid, where a vane mounted on the chassis could be submerged in or lifted out in order to provide a 2% minus or plus speed.
The difference in friction caused this way was perfectly calculated to achieve a two percent plus or minus variation of the then standard 33 1/3 rotations per minute (RPM). This was exceptional for a high-end turntable at that time, as the 33 1/3 or 45 RPM standard was strictly adhered to. Only later were pitch controlled turntables developed by different manufacturers in reaction to the demands made by a lot of DJs who needed this feature to allow beatmixing. In this case it usually concerns direct drive turntables instead of belt driven as they are more quickly on speed after holding the record by means of a slipmat.
The reference in this turntable also reflects on the possibility to mount various tone-arms on it. Often the Transcriptor turntables were outfitted with the Fluid arm, a one point, again in thick viscose liquid suspended arm, designed by David Gammon. In a later stage the Shure SME arm appears on the decks, also a class product, that allows for the use of later developed and more sensitive cartridges. Most of Davids designs were so far ahead of their time that it took a while for technical developments to catch up with them.