Paul Birkeland 6AV11 Preamp

Here we have one of my favorite preamps to date; a one-off Bottlehead type creation built by Paul Birkeland and based on the exotic and unknown 6AV11 compactron tube. This modest little pre has a swagger and sense of confidence that belies its small size and modest appearance, and it opens up the music in a way that makes preamps make sense. If that makes sense.

I have a storied and complicated relationship with preamps. I keep trying them out; in one season 7 units came and went, but ultimately I always return to the feeling that they are, at their core, great homogenizers. But sometimes I really enjoy the effect they impart; adding a sort of inflated grandness to the sound. Other times it takes my beautiful signal and runs it through the cleaners; stripping the soul and purity right out of it. Like running meaningless laps around a track in the 9th grade, its miles of wire in the way. And at the end of the day, you have to wonder what the hell you are doing.

In an age where every signal arrives with plenty of voltage, what exactly is the “pre” part doing? Most of the time I think we are looking at an effort to control volume or level and a way to switch sources without having to roll up your sleeves and remove interconnects, etc. The active “pre” part is almost an afterthought to those two conveniences. And in truth I think most of the time the active “pre” part is less than ideal.

Overall, I prefer passive devices for volume control and source selection. Of course, I’ve had a few active preamps that I really liked. The hard-to-find Eastern Electric Minimax is a gem, as was Kevin Brook’s WE448a monster. Radu Tarta’s UX201 was a special spotlight into the music that was almlost ethereal, but ultimately was physically difficult for me to use. My music is my relaxation. Difficult leaves quickly, even when it sounds great.

Which brings me to the preamp at hand, the 6AV11 by Paul Birkeland. Basically a one-off Bottlehead Foreplay, this one has three inputs, two outputs, and a nice clunky smooth action volume control. A small orange light tells the user “I’m on!” but unobtrusively. Yamamoto and Bottlehead have the soft indicator light thing down pat. Regardless, the beautiful little 6AV11 jewels glow brightly enough to be their own indicator. In use this preamp is functional but not frilly, as you would expect. But sound-wise, this simple looking little amp has a nice open presence and shines a big wide light, but still reveals plenty of detail without being edgy or pushy in any way. I’d guess it has somewhere around 10-12 db of gain and that seems to match pretty well with all of the amps I’ve run it into. Some of the higher gain preamps I’ve had through the small room have been so overpowering that it can be hard to handle, but this one is easy going and fits right in.

Back to back with an upgraded Transcendent Grounded Grid, the 6AV11 is my clear preference. The Grounded Grid has such a forward and turbocharged presentation; it can be thrilling to listen to but eventually becomes tiresome for me. In contrast, the 6AV11 doesn't appear to leave anything out, but it flows more calmly, and for the long run is easier to fall into.

We all need an active preamp now and then, for better or worse. When they are good they can be a special addition to the sound, and can add some flair or romance into a colder sounding amplifier’s presentation. I’ve tried 25 or more of them in over 20 years in this hobby. I’m also very picky, and as a result only a select few of them have made it onto these pages. I like this Paul Birkeland 6AV11 very much, even in spite of its top mounted inputs. For now it is staying in place as my go to pre for all of my low output single ended amps.

The small boost in power from a preamp is welcome company to the watt or so of power on my 6BX7 amplifier.

The 6AV11 seems to be a fairly microphonic tube in my experience, and I’ve had to use tube dampers or rubber band to control some of it. This tube type is almost totally unknown, so there is very little demand and they are inexpensive. I’ve tried a few brands but they all seem to sound about the same to me.

Here is the 6AV11 next to Don Garber’s 6922 preamp. I really liked the Garber preamp, although it was not perfectly silent. The 6AV11 is warmer and richer sounding than the Garber, but not as turbocharged. Both are superb performers.

Here is the 6AV11 feeding both the Toshi Kurashima 71a (above) and my Yamamoto A08S single ended 45 (below). Both of these amps need an attenuator, and although I always like the Luminous passive, the Birkeland 6AV11 adds some flair and expanse to the presentation, as well as a bit of perceived power, which is a welcome addition especially with the 71a.

The Yamamoto / 6AV11 combination is breathtakingly good!

This is an interesting tube. A 12 pin compactron, it is structurally several tubes inside one glass envelope. I’ve had a few amps built around compactrons in the past, Jeremy Fix’s 13EM7 and a 6N6G for example, and they can be really superb sounding tubes. Many of these types were made for early TV sets, but they can also be great audio tubes. And as a bonus they are just about obsolete now; no one wants them but there are still plenty of new old stock in the market at comparatively low prices. I like their sound and they are affordable, what more can you ask for?

A neat and unobtrusive interface. If the inputs were in the back it would be close to perfection. As it is, it's a joy to use and listen to.