Many thanks!
Transfiguration Phoenix S cartridge - impedance loading recommendation?
This cartridge has a low internal impedance of 1-2 Ohms, and the manufacturer recommends an impedance loading of >7 Ohms.
My phono stage (Accuphase AD 2900) has MC impedance settings of 10, 30, 100, and 300 Ohms.
I have tried it at 10, 30, and 100 Ohms and they all sound ok. I am running it at 10 Ohms for now.
What settings have you found to be best?
@toronto416 I ran that cartridge for many years. It was plug and play; my phono section has a 47K Ohms input (the industry standard for all cartridges). The only reason you might need loading is if your phono section is bothered by RFI generated by the cartridge, due to it being an active inductive device in parallel with the capacitance of your tonearm cables. RFI can really mess with audio electronics! But if the designer of the phono section was aware of this phenomena, it should be plug and play with no worries about loading whatsoever. |
I had discussed this with Bob Clarke, the distributor for Transfiguration before they stopped production and he felt that the Transfiguration carts were smooth enough on top that the loading became more of a tone control. The preamp we were discussing had loading from 100 to 470 and he said he even ran his at 47k. He initially suggested the 470 setting, but said it would work fine at 100. Just go with your sonic preference. We didn’t discuss any values below 100. Disclaimer- we were specifically discussing the Orpheus, which is low impedance, although not as low as yours. |
If the internal resistance of the Transfig is 2 ohms, not 1 ohm, you might be slightly better off setting the input impedance of the Accuphase to any number above 10 ohms. This is only because you want ideally the input Z to be at least 10X higher than the output Z, for any two components where one drives the other. It primarily affects the efficiency of energy transfer, in this case signal voltage. The rule is rather plastic when it comes to phono cartridges driving phono stages, so I would not worry about it much, but maybe try 30 ohms or higher and see whether the system becomes a bit more dynamic or produces higher SPLs at lower settings of the attenuator. In some cases, where the inputs have some capacitance, the ratio also affects transfer of high frequencies. In the case of a bad mismatch, you’d expect some audible roll-off in the treble region. I doubt that would be a noticeable problem with your current choice of input impedance. |
Many thanks @rauliruegas |
Dear @toronto416 : MC cartridges are not sensitive tochanges in loading impedance but a " not so good " phonostage design it couldbe. I owned the Phoenix and other Transfiguration models, the one you own is truly and has a very good quality performance levels.100ohms is OK. Your Accuphase unit is very good design too, so no problem at all. Regards and enjoy the MUSIC NOT DISTORTIONS, R. R. |