I need your advice for the following:
I own a Sony PS-X9 with build in RIAA and head amp (selectable), a Marantz PM 94 with again selectable RIAA and head amp. As I have a Denon DL-S1 MC cartridge with an AU-QS1 step up transformer I was wondering which RIAA is best to use (Sony or Marantz). Does it matter in which order you put RIAA and head amp (transformer)?
Thanks for your help! Much appreciated! 🙂
I own a Sony PS-X9 with build in RIAA and head amp (selectable), a Marantz PM 94 with again selectable RIAA and head amp. As I have a Denon DL-S1 MC cartridge with an AU-QS1 step up transformer I was wondering which RIAA is best to use (Sony or Marantz). Does it matter in which order you put RIAA and head amp (transformer)?
Thanks for your help! Much appreciated! 🙂
Yes it matters a lot.
Cartridge > head amp or transformer > RIAA.
SUTs are designed to work with a narrow range of cartridge source impedances, and signal levels and intended for use between a cartridge and RIAA amplifier.
If the pre-amp has both MC/MM options try both, but use the transformer / head amp only with the MM input option.
Cartridge > head amp or transformer > RIAA.
SUTs are designed to work with a narrow range of cartridge source impedances, and signal levels and intended for use between a cartridge and RIAA amplifier.
If the pre-amp has both MC/MM options try both, but use the transformer / head amp only with the MM input option.
That's what I thought, however I wasn't sure it would make any difference whether you put the transformer before or after RIAA amp. Is there a technical/ logical explanation for the above order? (step up trafo 3 - 40 ohms, boosting ratio: 1:13)
The answer is in the second line of my response. 😀
And in addition SUTs are not designed to operate at line level (they will saturate and distort badly if the RIAA doesn't first) and the RIAA is not designed to drive a 1:13 step transformer intended to reflect a load impedance of a few tens of ohms to an LOMC cartridge..
And in addition SUTs are not designed to operate at line level (they will saturate and distort badly if the RIAA doesn't first) and the RIAA is not designed to drive a 1:13 step transformer intended to reflect a load impedance of a few tens of ohms to an LOMC cartridge..
There are several reasons why cartridge - transformer - amplifier is the correct order. The most fundamental one is this:
MC step-up transformers are meant for connecting an MC cartridge to an input designed for MM cartridges. Such an input is (or should be) noise-matched to the impedance of a typical moving-magnet cartridge, which is much higher than the impedance of a moving coil cartridge. Very often, reducing the equivalent input noise voltage of an amplifier goes at the expense of increasing the equivalent input noise current and vice versa. The source impedance determines what matters most; for high source impedances, the equivalent input noise current is much more and the equivalent input noise voltage much less important than for low source impedances.
Hence, a well-designed RIAA amplifier for moving magnet cartridges will typically have too much noise voltage for a moving-coil cartridge. By putting the transformer in between MC cartridge and MM RIAA amplifier, the impedance is transformed to something a bit closer to the impedance that the MM RIAA amplifier was designed for, giving a better noise match. That is, the stepped-up voltage will more easily overcome the noise voltage of the amplifier.
When you would connect the cartridge straight to the amplifier and put the transformer after the amplifier, the amplifier first messes up the signal-to-noise ratio with its too high equivalent input noise voltage and then the signal with messed-up noise floor is stepped up by the transformer.
On top of this, the step-up transformer might go in saturation because it is not designed for the levels coming out of the RIAA amplifier. Also, the RIAA amplifier may go into current clipping because it is not designed to drive a low-impedance transformer.
MC step-up transformers are meant for connecting an MC cartridge to an input designed for MM cartridges. Such an input is (or should be) noise-matched to the impedance of a typical moving-magnet cartridge, which is much higher than the impedance of a moving coil cartridge. Very often, reducing the equivalent input noise voltage of an amplifier goes at the expense of increasing the equivalent input noise current and vice versa. The source impedance determines what matters most; for high source impedances, the equivalent input noise current is much more and the equivalent input noise voltage much less important than for low source impedances.
Hence, a well-designed RIAA amplifier for moving magnet cartridges will typically have too much noise voltage for a moving-coil cartridge. By putting the transformer in between MC cartridge and MM RIAA amplifier, the impedance is transformed to something a bit closer to the impedance that the MM RIAA amplifier was designed for, giving a better noise match. That is, the stepped-up voltage will more easily overcome the noise voltage of the amplifier.
When you would connect the cartridge straight to the amplifier and put the transformer after the amplifier, the amplifier first messes up the signal-to-noise ratio with its too high equivalent input noise voltage and then the signal with messed-up noise floor is stepped up by the transformer.
On top of this, the step-up transformer might go in saturation because it is not designed for the levels coming out of the RIAA amplifier. Also, the RIAA amplifier may go into current clipping because it is not designed to drive a low-impedance transformer.
No idea, I never heard of ultra low output MC cartridges until I read your post. One would expect the step-up ratio to be larger than for normal MC.
I somehow managed to have two of ancient RCA transcription tonearms together with proper moving ribbon cartridge and two transformers. Cartridge of no interest to me as it's tracking force is 25grams. However, transformer may work with ultra LOMC, because those are relatives with ribbon carts. With average LOMC it gives sound with no LF and too much of HF.
I suspect it may properly work with something like Ikeda, Neumann or AT ULOMC.
I suspect it may properly work with something like Ikeda, Neumann or AT ULOMC.
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As Marcel explained, whilst a 'normal' LOMC (say, 0.3mV) can use a 1:10 or 1:15 ratio SUT to match your typical MM phono stage, a VLOMC - I believe there is a Denon which has an output of 0.1mV - needs, say, a 1:30 or 1:40 turns ratio.
That, per se, is not a problem but it does have implications on the load the cart sees, as a SUT reduces the Zin of the MM phono stage - typically 47K - by the square of the turns ratio. So a:
* 1:10 SUT makes the cart see 470 ohms, but a
* 1:40 SUT makes it see only 29 ohms.
Freedom from this constraint is the reason why I prefer to use a headamp, rather than a SUT, as the cart loading is independent of the gain.
Andy
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