thanks for the comparison
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.
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@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. |
The mention that the FRT4 has its own leads (presumably from its outputs to the phono inputs), stimulated me to learn more about it, because the claim led me to believe the FRT4 might bear "flying leads" at its outputs. That means that the interconnect to the phono stage would be hard wired internally to the FRT4, thereby eliminating connectors at the output, which I view as a good thing. But I found photos that show this is not the case; the FRT4 has ordinary RCA jacks at its outputs. So what did you mean by saying it has its own leads? Further, the review I found was very helpful in showing a schematic of the FRT4 which reveals that it places an 18K resistor in parallel with its outputs, regardless of the step up ratio chosen for use. This would dramatically alter the impedance seen by the cartridge, compared to driving the typical 47K ohm input impedance of a typical low gain phono stage. (18K in parallel with 47K would result in a resistance of ~13K ohms.) Driving the net resistance of 13K ohms could be problematic with certain cartridges and if selecting step-up ratios higher than 1:10, even with low internal resistance LOMCs. The reviewer commented that the FRT4 sounded better (with whatever cartridge he used) when he removed the 18K resistor. Do you know whether that surgery was performed on your unit? |
I think all of Fidelity Research SUT have output leads. The one you saw maybe was modified? I have the FRT 3 and I think the leads came straight out of the transformers. At least they weren't any soldered connections on the outputs; I didn't dive any deeper than that. I didn't see any resistors in mine either. |
I believe what you guys say, but see photos here. In the review I read, the reviewer said he found the 18K resistor when he opened the chassis. So it seems he did not install it. He also posted a schematic that it seems he drew up based on what he observed. It’s not entirely a crazy idea. If you have a low output, moving coil cartridge with an internal resistance of less than 10 ohms and if you want it to be loaded with approximately 100 ohms, and if you are using a one to 10 step up ratio, then the addition of the 18 K resistor results in the cartridge seeing a 130 ohm load which works just fine. Where you could get into an issue is if you use a low output cartridge with a higher internal resistance. |
Dear @scar972: " top end doesn't sound as open and airy as the FRT-4 "
Look that output lead is and advantage only with today better IC cable but in your case is not and that " open and airy " in reality is only developed distortions. I still own the Entré ( I owned over 15+ different SUT. ) and owned the FR and at least according my reproduction MUSIC targets the Entré 100 is superior to the FR.
Regards and enjoy the MUSIC NOT DISTORTIONS, R.
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@rauliruegas Which is superior is really system dependent and preference of the listener. |
@scar972 : " Which is superior is really system dependent and preference of the listener. " Everything the same not really system dependt but more on the listener/owner MUSIC reproduction targets: which one achieves better what he is looking for.
R. |
@scar972 , thanks for posting your results. I have wondered what those FR SUTs sounded like. A another one you may want to consider is the Cinemags on the Ned clayton base. He sells them on ebay. The Mitchell Cotter SUTs have always been highly thought of but are not easy to find. And if a person wants to go a bit further, the Ypsilon SUTs are really amazing sounding. |
@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. |
