Stereo Sound #55, summer 1980
Reviews by Fuyuki SEGAWA and Keizo YAMANAKA

TT test by SS is using this special jig for measurement of rumble.
Usually rumble or S/N at turntable is measured as follows (DIN 45539):
1. test record with plain groove (no modulation) and 315Hz modulation groove.
2. play back these grooves with cartridge and compare difference between above outputs after passing prefixed filters
3. and indicate rumble or SN in dB as noise margin.

Above DIN method is internationally accepted and IEC/JIS rumble test are very similar to DIN.
DIN FILTER A (unweighted): more than 35dB is required for minimum quality for equipment
DIN FILTER B (weighted): more than 55db is required for minimum performance of equipment.
Rumble rate measured with DIN B filter is indicated usually in catalogues to show impressive big number of S/N !

But Ladegaard of B&K in 1977 mentioned "At FILTER B the numerical value appears better than FILTER A, but in the territory of SN 65dB it is not something which tells the quality of the turntable. At FILTER A, the numerical SN value looks worse about 20dB, but it is just influenced by the resonance frequency of the cartridge and the arm. Unless the rumble spectrum is analyzed, rumble from the vibration of the motor proper cannot be acertained".
Thus in 1978 Thorens developed new jig for rumble test and applied once on the test of their turntables (1978-1985?).
SS documents are very rare test reports using this jig on other players than Thorens. This coupling jig is mounted on the spindle of turntable and there is "friction-free" bearing between spindle top to the spot for cartridge. Actually there must be some friction or mechanical coupling which affects the behaviour of turntables or cartridge output. Hence any standard including IEC98 (1987) etc does not accept such method. Anyhow SS documents show interesting experiments as the reports on measuring.

Click the thumbnails to the right and the results open in pop-ups so you can put two LP spinners side by side and easily compare the results - ain't I thoughtful ?
To see the procedure and equipment involved in this test, click the little thumbnail.

And the winners are:
EMT 930st

Pioneer Exclusive P3

Sony PS-X9

Micro RX/RY-5000

(Knowing the fascination japanese journalists seem to have for anything EMT, I'd shift that podium up by one position ;-)

10
(5+5)
10
(5+5)
8
(4+4)
8
(3+5)