Fosgate Signature Tube Headphone Amplifier
Fosgate Signature Tube Headphone Amplifier ($1499)
When famed audio designer Jim Fosgate first announced that he was going to be making a tube headphone amp, I was definitely interested, especially when I saw the first pictures of itit's a beautiful product. For a variety of reasons, it took quite a while for me to actually hear one, which was at a Chicago headphone meetand on that cursory listen I thought it sounded good. So finally, a review unit arrived for me to really put through the paces.
The $1,500 Fosgate Signature is billed as a vacuum tube amplifier, but if I understand it correctly it is really a type of hybrid design, using a pair of 12AX7 dual-triode tubes in the input/driver stage (described by Fosgate as an "SRPP configuration"), and then "Video Buffers" as what amounts to the output stage. The video buffers are said to have no voltage gain, and as such, the Signature is a fairly low power amplifier, delivering (according to the excellent owner's manual) between 165 mW250 mW depending on the impedance of the headphone. This pretty much requires the use of a fairly efficient headphone. To that end, I used the Audio-Technica W3000ANV for the review, primarily. I did also briefly try the Audeze LCD-3, but as I expected, the Fosgate did not deliver enough power to drive them what I think of as properly. That said I was very impressed that there was absolutely no noticeable background hum or noise when using the W3000ANV. This is obviously a very good thing, and not always the case with amps using tubes combined with the very efficient AT's.
The Signature has a couple of unique featuresone is a patented bass EQ circuit, and the other is a "surround sound" function the stated goal of which designed to make the soundstage via headphones more natural. As I often find to be the case, whether I preferred these functions to be on or off depended on the music I was listening to at the time. Sometimes they were terrific and enhanced the listening experience, and sometimes they did not. Both functions are very, very subtle in effect. At the max setting of "Surround", the soundstage does seem to be coming from outside the headphones, and not in between them, but it doesn't put the image in front of you, so I actually didn't personally care for it most of the time. That said, on some jazz from the late 50's/early 60's, like "Waltz Me Blues" from Art Peppers' "Meets the Rhythm Section", the Surround feature helped to make what's a bit of a ping-pong stereo mix a bit more enjoyable, although this a track that I don't think works all that well with headphones outside of using the MONO switch on my vintage Pioneer amp.
On the other hand, the two bass boost settings were often VERY useful, and this is a great feature to have, given that the amount of boost is very subtle even with "MAX". Good stuff. One thing to note: the use of the Surround feature does actually reduce apparent bass weight (often the case with crossfeed type circuits), and as such, the use of the bass boost is almost mandatory if one chooses to use the Surround function.
There are some other niceties like a 35 second muting circuit to eliminate turn on transients, and two inputs with a front panel selector switch (note to manufacturers: rear panel selector switches SUCK, so Fosgate gets credit for doing it right).