Talk Vinyl: 3 SUTs - Denon AU-250 and AU-300LC; Fidelity Research FRT-3G
After the initial round of testing (Part I), I decided to try out some SUTs in lieu of the active phono pre-preamplifiers. System remain unchanged otherwise:
Analogue setup: Garrard 301-Thomas Schick 12"-Midas Denon DL-103 (pic above)
Preamplifier with MM stage: Leben RS28-CX
Amp: Wavac MD-300B
Loudspeakers: Tannoy Canterbury HE
left pic: Denon AU-250 atop Leben RS28CX; click to enlarge. Right: AU-300LC
Denon AU-250 vs AU-300LC
Both are entry level SUT from Denon. The AU-250 is from an earlier generation and there is little information on the net.
Spec's Both have 1:10 step-up ratios with input impedance (40 ohm) tailored for the Denon DL-103, certainly the industry standard in Japan, if not the world. The later AU-300LC employs oxygen-free copper (hence the LC designation) and is still a current model. Here is a AU-300LC pdf file. Note that the AU-250 does not have a ground lug on the input side. I found in this setup the Schick does not need to be grounded, which makes life easy.
Sound First, let it be known that the two sound very similar. Both sound completely coherent with the Midas Denon DL-103 and in this setup outperform the active devices previously used. Indeed, on the replay of two seminal canto-pop albums (pics borrowed from my friend LeeHC, from the wonderful vinylparadise), the sound is some of the best analogue sounds I have heard from this setup (although the 12" still remains just a tad slow). As expected from the use of oxygen-free copper, the sound of the AU-300LC has a little more high-frequency content than the AU-250. This is similar to the difference between DL-103R (which also uses oxygen-free copper) and the regular DL-103. However, and this is important, the AU-250 is a little more fleshed out in the midrange. I am not sure which one is better; I think it depends on the system. This round I preferred the AU-250. This reminds me of my experience of the DL-103R: I have not yet personally tried it, but on several systems I heard the 103R tended to be a bit on the lean side and I have always suspected the regular DL-103 is a little more musical. On the canto-pop albums the voices are just a little more real with the AU-250. Keep in mind the differences, though audible, are small.
Spec The spec of the FRT-3G can be found here. Comparison shows it to be very close to the more common FRT-3 in the excellent vinylengine SUT database. Please note that this transformer has two gain settings, and the low-gain one is more suitable for the DL-103. However, the step-up ratio, about 1:20 is twice that of the Denon AU250/AU-300LC. The recommended input impedance (15-40, likely 30 ohm) is likely commensurately lower.
Sound When I compared it some time ago in my own system using the DL-103, I preferred the FRT-3G to Denon's own AU-300LC. In my system the FR proved to be more richly hued. Then I loaned it to a friend. His system:
Analogue: Clearaudio Champion-modified Rega RB-300-Denon DL-103R
Preamp: Audio Research SP-11 MkII
Amp: Rogue Audio KT-88
It is a balanced and good sounding system. On that occasion I also took with me the Denon AU-300LC and compared the two. The result was similar to my earlier findings. The FRT-3G simply sounded richer. Note that in both systems the difference is much greater than the difference between the two Denon's.
It is interesting that with my current setup, the AU-300LC does not really exhibit undue leanness. When I get my FRT-3G back, I am most eager for a re-match. I am also most eager to try the FRT-3G on the FR MC-202 cartridge, as it is a sure match.