Regards, Thuchan: "IF you pull the measurement card". This depends on which "deck" one is dealing from.
Would like to find the entire SS review, only able to find pieces here & there.
This one is also interesting:
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?).
Depends on when measurements are taken, DIN B procedures enabled Pioneer to elevate S/N from 78dB to 95dB, with what seem minor changes the P3a was launched.
Pursuing research on the Pio. Exclusive, this turns up on The Vintage Knob:
"(So) where does the 78dB > 95dB difference come from ?
I asked him that too because I was exasperated at not being able to explain it based on changes. His answer, translated and redacted, comes out as the following :
"It is 'numbers magic'.
Sometime in the very early 80s, the EIAJ (Electronics Industry Association of Japan) changed their DIN B measurement methodology to, according to the marketers, 'better measure what the ear hears'. They changed something to account for the shape of the human ear.
Left largely unannounced, they 'flattened' the weighted curve, and added another filter, which had the effect of raising S/N ratios by 'about 20dB' depending on the piece of equipment being measured."
I asked him whether they measured anything when tables came in to get repaired. He said that in fact they measure all tables according to that newer "DIN B (EIAJ, A-network) standard because that is the machine they have now.
When I asked how much better the P3a measures vs the P3, he said, "They come out the same : non-statistically-significant sample difference".
The only difference which comes out in testing is a lower speed drift amount : the P3a has a potential speed drift of half the P3 (though when they service the P3, they tune it to P3a control specs).
I then asked whether --- any of the other mega tables which showed such great specs ---, "No, but the whole curve shifted upward for everyone - there was no way to avoid it."
--- the thing to measure to check real rumble differences would be the JIS rumble spec which used continuously from the late 1960s or early 1970s.
In that way you could compare like-for-like across time and manufacturers."
Gotta confess, have never heard an EMT deck, possibly never will, I am giving consideration to the P3. I've an Exclusive PL-70L 11 I occasionally run but (sacrilege) prefer a garage modded JVC 71 for it's ebullient character.
I've no dog in this hunt but do find the conversation fascinating. Thanks for initiating this thread.
Peace,