Tube Power Amps

If you're thinking you've just heard the war cry of Tim "The Tool Man" Taylor, from TV's long-running sitcom Home Improvement, you'd be...wrong. No, that was Luke "The Tube Man" Manley, from high-end audio's long-running manufacturer VTL, and he's trying to convince me that, when it comes to amplifier power, more is definitely more.

"One ST-85 is fine when you're driving these Joseph Audio RM-7si's, and probably with the Thiel CS.5s, but I think those NHT 2.5i's would work better with two."

"Maybe so, Luke, but how's about I go with just one amplifier for a while? After all, that's what most people would buy, at least at first. Then I can drop in another one and see what that does."

Luke agreed, and left me to my listening. I was surprised that he had that reaction; after all, the ST-85 is rated at 85Wpc. Oh—that's into four ohms. VTL doesn't quote a rating into 8 ohms, since the VT-85 is optimized for a load of around 5 ohms, but Luke says that the 8 ohm rating would be around 70Wpc. That still strikes me as plenty of power, but Luke seemed pretty adamant. Maybe two ST-85s would help—if help was needed. After all, you can't judge a component by its specs. You've got to listen.

Simplicity itself
The VTL ST-85 has the same look as the rest of the VTL amplifier lineup: it's a black box with hefty handles and those five distinctive horizontal cutouts, each one longer than the one below it. The only other features on the clean front panel are the power switch, the power LED, and the VTL logo.

On the back, things are more Spartan than usual for a tube amplifier—instead of multiple positive terminals for various loudspeaker loads, there's only one set per channel. As I said above, the ST-85 is optimized for a 5 ohm load, a value within spitting distance of most conventional loudspeakers. Using only one output terminal means that the output transformer's entire secondary is used; with multiple taps, some of the current transferred from the primary is potentially wasted in the unconnected part between the tap and the end of the secondary. Furthermore, VTL takes negative feedback from this single output at the end of the secondary, making it truly global—the entire amplifier (and the speaker cable, to their way of thinking) is included in the loop, something that couldn't be done with multiple taps.

The speaker terminals are unique to VTL: tall, four-way binding posts, or at least that's what I'd call them. Five-way posts allow end-on insertion of banana-type connectors, which these won't allow, as the end is a gold-plated hex head. Five minus one equals four, even though I've never been able to tell what all five methods are. Also on the back are an IEC power receptacle, fuse holders, and a pair of RCA jacks.