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Dear Thuchan, Do you have some general criteria for SUT's use?
Should they be used by all LOMC or is the output not relevant?
An SUT (Some call them Head Amps) are needed if your phono stage doesn't have enough gain to deal with a low output cartridge. For example, if you have a phono preamp that supports MM only and you have a LOMC, you would need an SUT because a lot more gain is needed for that type of cart.
This particular case is interesting because the OP has a phono pre that should support a LOMC, but in reality the lower the voltage, the higher the quality of phono stage is needed for comparable SQ. Especially since his phono pre uses tubes. With a cart output of .3, you're asking a lot from the phono stage. It will be pushed right to its limit.
In my opinion, its 50/50. Try the Pro Ject first, by itself, and if it sounds OK that's all you need. If you get some noise or distortion, then it would be wise to switch back to MM and use a SUT.
"An SUT (Some call them Head Amps) are needed if your phono stage doesn't have enough gain to deal with a low output cartridge."
This may be pedantic, mb1, but I think SUT is specifically a passive step-up using transformers (hence the "T" in SUT), while a head-amp uses active electronics to boost the signal; it needs a power supply, an SUT doesn't.
Their merits are debated. SUTs are 'pure' — head-amps add distortion.
But SUTs pick up hum — head amps don't. But head-amps are noisy — SUTs are dead-silent. Some head-amps use batteries to solve the noise issue. My head-amp plugs into the wall, but I improvised a battery supply (easy, it only needs 12V). Frankly, I hear no difference, no noise either way — but I learned long ago my ears aren't golden... and turning 70 didn't improve them.
I have both SUT and head-amp. I usually decide which to use depending on cartridge, trial and error to see which match I prefer.
But I have a new principle — I use my head-amp when using a passive line preamp to drive my power amp, because passives can lack dynamics and 'flatten' the music — the head-amp, being active, restores dynamics: I can clearly hear more rhythmic drive and sonic contrasts.
But when using a normal active line preamp, I use the SUT, because I'm not lacking dynamics. I get the SUT's purity, without the trade-offs.
Maybe just my latest meaningless fad, but so far seems to work for me.
Another virtue of head-amps is they usually offer more adjustments (impedance, even capacitance) than SUTs, to cater to different LOMCs' requirements.
Hope this makes sense...
SUTs are 'pure' — head-amps add distortion
Transformers are NOT without their own distortion. Some just prefer that to the distortions generated by active devices such as FETs.
Some head-amps use batteries to solve the noise issue.
Batteries will not eliminate the inherent thermal noise of the individual components themselves. Current flowing though any resistance generates noise.
Czarivey, I agree HOMCs are tempting. I've had 4 of them... but so far none compete with my favorite LOMCs. Only one of them is in the ballpark, but it's warming the bench. But that might just be my limited experience.
Thanks John for the clarification. Every time I check this forum I learn things.
I was hyperbolic stating that SUTs have NO distortion -- but would you say they have less? Or merely different?
Similarly I was inaccurate in describing noise in head-amps. But do you think eliminating the noise coming from the standard 120V our utility companies give us does have benefits, and batteries can bring an improvement?
As I mentioned, I personally hear little difference, if any, so I'm just musing on theory...