Listening #88 / Tempo Electric Arthur Loesch 1.1 Control Preamplifier Page 2

The second phono gain stage uses an RCA 6GK5 tube. The 1.1's third and final phono gain stage incorporates half of a Tung-Sol 5687 dual triode—the second half of which is used to provide 18dB of line-stage gain. That tube, like the abovementioned 6GK5, is used in a fixed-bias arrangement originated by Dr. Loesch, wherein the DC for the tube's signal grid is supplied by a replaceable battery. (In a product such as this, with a comparatively low voltage rail—260VDC is the intended B+—the traditional advantages of an auto-bias circuit would be moot.) In exchange for the slight inconvenience of replacing batteries once a year or so, the Loesch approach seems to offer advantages in noiselessness and in freedom from the need for periodic bias adjustments.

Signal-path parts in my review sample of the Arthur Loesch 1.1 were top-shelf, some having been selected in listening tests described on the Tempo Electric website (www.tempoelectric.com). Vishay and Dale resistors abound, the latter also appearing—by the dozens!—in the dual-mono stepped attenuators from Goldpoint. (Tempo uses ladder-style attenuators, which require twice as many resistors as the shunt type.)

Likewise, Tempo Electric didn't cheap-out when it came to the 1.1's outboard power supplies, each of which contains five tubes, most apparently for regulation or for ramping up the power to other parts of the circuit. The B+ is rectified with a 5V4 tube, while the 6.3VDC for the heaters is handled by a solid-state rectifier bridge. Also of note are the rugged and delightfully retro-looking transformers and chokes from Peter Dahl & Co., and the front-mounted voltmeters and 10-turn trim pots that allow one to monitor and adjust the rail voltage.

Besides the dual-mono power-supply option and the gain-stage configuration described above, my review sample was equipped with an optional mono switch. As with most such controls, this one worked by blending together the left- and right-channel signals: fine for mono CDs or most modern mono phono cartridges, the latter usually having two pairs of live output pins. But to produce sound from both loudspeakers with "true" mono cartridges—which, like my EMT OFD 25, have only one pair of live pins—the user must hook the preamp's No.2 left-channel and No.2 right-channel output jacks together with a short bridge interconnect (included).

The flexibility of the Arthur Loesch 1.1 doesn't end there. Among other useful features, the preamp has a rear-panel switch—a lockable toggle—to select between floating the signal ground relative to the AC line or not. As it turned out, the latter ground mode performed best when I first installed the 1.1, with the phono inputs being driven by the Hommage T1 step-up transformer. But later on, with the cartridge's output directly driving the 1.1's phono stage, I experienced with phono and line sources alike a moderately severe hum that couldn't be eliminated with a ground lead. Floating the signal did the trick.

A final setup note: Phono load impedance is easy to adjust on the 1.1, given a good supply of the "nude" Vishay resistors preferred by Tempo Electric. There are two pin sockets next to each 417A tube, and you simply install your resistor of choice, or leave the standard 47k ohm resistors in place. Knowing that my collection includes a Miyabi 47 low-output moving-coil cartridge, Joe Levy made sure to supply a spare pair of resistors, in the Miyabi's preferred value of 100 ohms.

Lesh is more
The Arthur Loesch 1.1 Control Preamplifier confounded more than just my expectations of its build quality. Accustomed as I am to associating expensive, bespoke electronics with an approach in which connoisseurship—especially regarding one's choice of tubes—takes the place of subservience to a monolithic absolute, I was surprised that the 1.1 didn't sound at all tubey, in the accepted sense. In fact, compared with its sound through my Shindo Masseto preamplifier, the first record I listened to through the 1.1 sounded brighter than I like. Quite a few that followed, too.

So throughout the next couple of weeks, rather than expecting the new preamp to adapt to my listening preferences (footnote 2), I tried adjusting my system and my habits to the very wide and altogether modern frequency range of the Arthur Loesch 1.1. The involving and pleasantly midrangey Shindo SPU suited it best of all the cartridges on hand, as did the Audio Note AN-E loudspeakers (contrasted with the Wilson Audio Sophias and Sashas that were in for review) and Auditorium 23 speaker cables (contrasted with the upper-echelon Nordosts, also in-house). I moved my listening seat a little farther from the speakers, too.



Footnote 2: As I was told early in the review process, my sample had already spent time with another reviewer; consequently, break-in wasn't an issue.
Article Contents
Share | |
Site Map / Direct Links