I have a SUT I built with Cinemag 1254s and I decided to place them inside my phono preamp to get rid of a set of interconnects and just because I want to.. It is a modified Hagerman Cornet 2 with an external PSU.
I got to thinking that if I put the step ups in the turntable (a highly modified Technics 1200, RCA jacks, external PSU, carbon fiber tonearm) then the very low MC output signal would be travelling a minimal distance. Regardless of where I put them I will install a bypass switch in case I put a MM cart.
I have never heard of someone putting the step ups in a turntable but I cannot think of a reason why I can't. I have training and used to be an electronics tech.
What do you guys think?
I got to thinking that if I put the step ups in the turntable (a highly modified Technics 1200, RCA jacks, external PSU, carbon fiber tonearm) then the very low MC output signal would be travelling a minimal distance. Regardless of where I put them I will install a bypass switch in case I put a MM cart.
I have never heard of someone putting the step ups in a turntable but I cannot think of a reason why I can't. I have training and used to be an electronics tech.
What do you guys think?
Well, turntables have a motor, and won't the motor have an electrical field around it which could be a source of hum for a SUT?
And, some turntables just don't have a place to put them.
jeff
Should work, especially if you use mu-metal to shield the SUT,
and keep it near the base of the tone arm.
David is correct. Any capacitance present between the SUT and phono stage will be multiplied by the square of the SUT's primary-secondary coil turn ratio. If the SUT gain is 20dB, any capacitance present between the SUT and phono stage will be multiplied by 100; a gain of 26dB will result in a capacitance multiplication factor of 400.
While there are benefits to placing a headamp so that it is closer to the MC cartridge and therefore farther from the phono stage, the reverse is true for SUTs.
It is a reflected impedance based on the turns ratio of the step up transformers.
I don't believe any MC is designed for 100R loading and the ones that are recommended to be loaded with that are generally under 10Ohms. I'm possibly missing something but how is that close to the impedance of a 50 or 75Ohm coax?
Strictly the impedance of coax or twisted pair is only valid at high frequencies, where jwL and jwC dominate R and G and the 50/75R values don't apply at audio frequencies.
In practice twisted pair is in hundreds of Ohms in the audio band, so not going to cause impedance errors if you extend a long cable from the MC cartridge to a 100R stepup transformer
In practice twisted pair is in hundreds of Ohms in the audio band, so not going to cause impedance errors if you extend a long cable from the MC cartridge to a 100R stepup transformer
It is low VOLTAGE, true.
It is higher available *current* than a MM needle.
The available *POWER* is about the same MC or MM.
To a first rough approximation, the interference or signal loss is about the same either way, almost, roughly. Not like either is "weaker", though they are both weak.
After all: when you run MC through a transformer (power out equals power in) you get "MM signal".
47k MM signals suffer from capacitance of "long" lines, and the 47k ballpark seems to assume 3 foot leads. (90pFd in cables, 90pFd grid capacitance, makes very nearly 47k at 20KHz.)
50 Ohm MM needles can drive thousands of feet of wire but ohmic losses may matter at 1000' of heavy wire or 100' of skinny wire. If we had a good low-hiss 50r active amplifying device this might not matter (its Zin may be much higher than 50r). If driving a transformer (because good low-hiss@50r devices are scarce) we may need to sharp-pencil the situation.
As said, there is 50/60Hz everywhere, in turntable and often in preamp, and this gets into the audio transformer.
Personally I think I would run the low-Z line out and let the SUT be in the preamp.
I am now more confused. The majority of LOMC are 3-12Ohms with outliers down to 0.1Ohm and up to 40 Ohm. I don't see where you are going.
The stepup transformer or most MC preamps present a 100R load to a LO MC as standard.
Adding a ~100R twisted pair between them still means that the cartridge sees 100R.
The cable would have to be very long before its loss and actual impedance became significant, far more than 10m.
Telephone pair cables work at kilometers before they need equalising
Adding a ~100R twisted pair between them still means that the cartridge sees 100R.
The cable would have to be very long before its loss and actual impedance became significant, far more than 10m.
Telephone pair cables work at kilometers before they need equalising
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