Step up transformer recommendation

@agrogon 

Most of the advice offered above is nonsense and will not work.

Your Audio Research PH3SE is designed for MC's and has 54db of gain.

According to the manual it will suit MC's from 0.25mv up. Your Rega Apheta is 0.35mv, well above the minimum output required.

Most moving magnet phono stages have about 40db. Your PH3SE does not have a moving magnet input.

The use of a 1:15/1:20 mc transformer will probably end up with too much gain.

You should try your Rega Apheta straight in first. There are binding posts inside on the circuit board to attach loading resistors to achieve the optimum load.

I would suggest you order some 100ohm, 400ohm resistors from somewhere to experiment in addition to the standard 47k input.

The AR Reference 3SE has

Gain:

Selectable 51 dB (Low) and 73 dB (High) at 1kHz BAL; 45 dB (Low) and 67 dB (High) at 1kHz SE. (MC and MM compatible).

Input Impedance:

47k Ohms and 100 pF SE. Selectable loads: 1000, 500, 200, 100, 50 Ohms, and Custom.

You would use the 45 dB setting and 47K ohm setting with a Step up transformer.

If it is the  PH3-SE, with a fixed setting of 54 dB of gain, then you would probably want to use a 1:5 or 1:10 step up.

I have the older PH3SE phono preamp 'not the reference'  I added the resistors for the 100 ohms input impedance adjustment.  The system played but at a really low volume, I could hear the music when I turned it up to 70% volume.  

Yes this preamp has a fixed gain of 54dB, probably do want SUT of 1:10?

Should I invest in SUT and use the PH3SE or would money be better spent on a dedicated MC phono preamp?  

I would love to hear what is recommended from others. 

@agrogon 

I would try and see if you can borrow a 1:10 transformer to see if the gain is right.

1:5 transformers are rare.

Have you tried the PH3SE straight in at 47k ?

K&K Audio offer reasonably priced MC step up's using Lundahl transformers.

Tthe basic kit using the LL9206 offers you 14/20/26 db selectable. They will build the kit for you - price is very reasonable. 20db is 1:10, 14db is 1:5 ( I think ).

http://www.kandkaudio.com/moving-coil-phono-step-up-kits/

I have a Slagle 1:5 SUT that I have been using successfully for a similar set up. I’m thinking about going to a different system so I may be selling it.