Looking for SUT for Air Tight PC-1 supreme

Might be worth contacting Dave Slagle at EMIA: http://www.myemia.com/welcome.html

Your Air Tight PC-1 has an output of .6mV with an internal impedance of 2.5 ohms, according the cartridge database. The problem is that it is a relatively high output voltage compared to the internal impedance. It depends on the overload voltage on your phono preamp as to how high you can boost the signal. Most phono stages overload at about 10 mV. So doing the math 10/0.6 = 1:17 is the highest step up ratio you can use. You can readily find 1:16 step ups, but they will give you a reflected impedance of 184 ohms. It should work fine, since the recommended loaded impedance is greater than 25 ohms. Impedance matching is not critical for SUTs, as long as the impedance load is not too low. Too high is ok. Some may recommend loading with resistors to make up the difference between the 184 ohms and the 25 ohms, but I personally find it is not necessary.

Even if you do not buy one of Bob's Devices SUT's, you should definitely visit his web site for a great deal of information. I have owned his superb CineMag based unit and currently his Sowther OCC based unit. Bob is helpful and generous with his time. He will match your cartridge to perfection.

Bob's Devices is reviewed by Art Dudley in the June 2010 issue and on 10Audio. Both reviews are available on line.

Thanks, I will check out both Bob's Devices and EMIA.
What I am confused about is that my PC-1 Supreme, not PC-1,is 0.4mV and internal impedance of 1 ohm. Recommended loading I believe is between 100-800ohms.
I suppose, anything from 1:10 to under 1:25 should be ok to use with my phono as far as gain is concern however 1:25 would have reflective load of 75 which may be too low.
Ortofon T100 is 1:20 with reflective load of 118 ohms.
I am not sure where to start. Should I look at a SUT that would have good reflective loading that match the cartridge first? If a cartridge sounds good when using MC phono at 100-120 ohms loading than 200 ohms then should I pick a 1:20 SUT over a 1:15 (assuming that multiplication factor will raise mV enough either way)?

For .4mV with 1 ohm, the maximum ratio is 1:25, if your phono overloads at 10mV. With MC cartridges, a basic starting point is to use an impedance of 10 times the internal impedance to be safe. Therefore the recommended loading will be anything over 10 ohms. There are exceptions like with Denon where lower impedance loads tame the high frequency response. So you will definitely be safe with 1:25 or 1:20. You might be fine with 1:30, if your phono preamp can handle 12mV without overloading.

I also have a Bob's Devices SUT. It is on of the best bargains in audio.

Thanks for all the comment. I am curious about B ob's Devices. The cinemag certainly has quite a bit of press lately but I am wondering if the Sowter might be a bit more flexible.Cinemag has either 1:16 or 1:30 with reflective loading of 184 ohms or 52 ohms (presumably too low for Air Tight recommended 100-800 ohms). The Sowter 1951 has either 1:10 or 1:20 so it is a bit more flexible as both 1:10 and 1:20 should work for Air Tight and it will be up to which loading sounds better with the cartridge. Anyhow, I am wondering if anyone has compare the sound of the Cinemag vs Sowter and what's your impression. Also has anyone ever compare either to Ortofon T100 by any chance?

Suteetat,

You might consider consulting Albert Porter's system page or pinging him...he runs an Air Tight Supreme, which sounded splendid when I heard it in his system :-)