Fidelity Research FRT-4 and Entre ET-100 step-up transformer SUT comparison


These two vintage step-up transformers are often mentioned together along with Denon AU-340 as the ones to consider if you're running multiple turntables and tonearms like myself. I have the Fidelity Research FRT-4 and Entre ET-100 and here's a quick summary of my experience between the two. I'm unaware of any current SUT offerings that allow for multiple inputs and multiple impedance selections, let me know if there's one out there.

The Fidelity Research FRT-4 boosts my LOMC signal without any negative side effects that I'm able to hear. Background noise is now almost non-existence, I'm hearing so much more air and natural extension on the top end from both of my LOMC's. Vocals just float in the air with beautiful imaging, an experience I hadn't had before adding this SUT into my system. Overall, this SUT sounds clean, clear, and punchy with just the right amount of meat on the bones for a balanced organic sound. 

The Entre ET-100 is a tad more laid-back-sounding compared to the FRT-4, the background noise is just as low with no negative side effect that I can hear. In my system, the top end doesn't sound as open and airy as the FRT-4. I love the way this SUT sounds with my jazz recordings, especially the few with a little more bite on the top end, the sound is more easygoing with this one. Build quality is just as good if not a little better than the FRT-4, and it's a little larger than FRT-4 which I was surprised by. The knobs feel smooth and sturdy with both of these units and I'm able to switch from one turntable to another without any noisy static through the speakers.

FWIW, the ET-100 allows you to use output cables of your choice, whereas FRT-4 has existing output cables. If there's a current SUT out there with all of these functions, it would garner much more than the price these two models are going for. I hope this helps someone who's considering between these two excellent SUT's.

scar972

Showing 6 responses by scar972

@theophile cartridge used, Lyra Kleos SL and ZYX 4D. Primary phono stage used is the Manley Chinook, I also tested on a couple of solid-state phono stages.

All of the FRT4 I’ve seen in pictures have output leads consistent with mine. I haven’t peaked under the hood to see if mine has the 18K resistor. Do you know if the 18K resistor is a mod or a part of the original design?

@johnss thank you for your recommendation, I have looked into several of those you listed. I’m focusing on SUT’s that have at least two inputs so I can run multiple tonearm/turntable, and even better if it has multiple impedance selection. I’m unaware of any current production SUT’s that has these features.

@dover thank you for pointing me to the Air Tight ATH-2 and Allnic AUT-800. I wonder if there's an improvement between current SUT's vs vintage SUT's, there haven't been any changes in the technology, maybe just silver vs copper windings. These current offerings are approximately 10X more than the vintage.