I bought them from a fellow member, this is the original thread. Not sure if I'm breaking rules.
https://r.tapatalk.com/shareLink?url...7&share_type=t
[IC]: RTJ Phono equalisers - experimental resistance/capacitance sets
Technics SP10 mk2
Jan Allaerts MC 1 Boron mk1 cart
Miyajima Shilabe cart
Hashimoto HM-X SUT
Siggwan (gimballed not unipivot) Cocobola 12"
Aurorasound Vida LCR Phonostage
The Truth linestage
Dave Slagle Autoformer Volume Controller
Cary 805c SET amps
Audio Note ANe-SPX speakers
Townshend Isolda speaker cables
Cardas Golden Presence interconnects
I'm not sure whether it's series or parallel to be honest - but I noticed no degradation in quality when I played with them and the Vida/Hashimoto.
Will check values and get back.
Technics SP10 mk2
Jan Allaerts MC 1 Boron mk1 cart
Miyajima Shilabe cart
Hashimoto HM-X SUT
Siggwan (gimballed not unipivot) Cocobola 12"
Aurorasound Vida LCR Phonostage
The Truth linestage
Dave Slagle Autoformer Volume Controller
Cary 805c SET amps
Audio Note ANe-SPX speakers
Townshend Isolda speaker cables
Cardas Golden Presence interconnects
The 3 pairs add, 30k, 75k, 150k - with combinations as per the chart.
Technics SP10 mk2
Jan Allaerts MC 1 Boron mk1 cart
Miyajima Shilabe cart
Hashimoto HM-X SUT
Siggwan (gimballed not unipivot) Cocobola 12"
Aurorasound Vida LCR Phonostage
The Truth linestage
Dave Slagle Autoformer Volume Controller
Cary 805c SET amps
Audio Note ANe-SPX speakers
Townshend Isolda speaker cables
Cardas Golden Presence interconnects
Firstly, putting resistance in parallel with the input can only reduce the input impedance. You can raise the input impedance with a series resistor but I wouldn't recommend that because you will be attenuating the signal going into the phonostage and degrading the signal-to-noise ratio.
Secondly, having a low input impedance is unlikely to make the cartridge sound shrill. If anything, it's more likely to make it sound dull. More likely still is that the sound will be fine at 47 ohms. Yes, it's a bit lower than is common but it will be fine with many LOMCs. Just choose a cartridge with a source impedance less than 12 ohms and you will be ok, and there are lots to choose from.
BTW, the idea of changing an internal resistor might work, but that will depend on the circuit. With simple op-amp circuits it probably would work, but it might be a completely different type of circuit. Also, if it uses surface mount components it could be an extremely fiddly job. Some surface mount components are hardly any bigger than a grain of sand!
Thanks for the info, I'm just puzzled why Schiit have set their input impedance lower than everyone else. The one review of the Mani on YouTube I've seen concluded that the MC performance of the Mani was inferior to its performance on MM which they rate very highly, my worry is that changing to a cartridge which is not optimal on MC will actually give me worse performance than my Nagaoka MP110. Both AT cartridges I'm considering are 12ohm coil impedance.
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There's an almost trivially simple way to "design" a preamp for a LOMC, and that's to use an opamp. The resistor which defines the load impedance in such a circuit can be almost anything, and it's often set at about 100 ohms.
However, if you design a circuit using discrete transistors it isn't so simple and the available range for the input impedance could be constrained by other elements of the circuit such as resistors used to bias the transistors. I don't know the details of the Schiit circuit so can't offer a more detailed explanation.