Vacuum Tube Valley 6B4G Monoblock Tube Amplifers

I’m not really a fan of monoblock amplifiers. I understand the idea, each amp has its own power supply and is isolated from the other signal, etc, But from an ergonomics perspective, I’ve got to find room for TWO amps, not just one, and in my space that can be a challenge. But something about this pair of monoblocks drew me in nonetheless. Perhaps it's the Vacuum Tube Valley reference, maybe it's the 6B4G…I mean a push pull 2A3 is a good place to be one would think. Maybe it's the hammertone paint? Lance Cochrane has made me a sucker for the stuff.

At any rate, I snapped up these 6B4G monos from Audio Asylum and am so happy I did. These amps are performers! The 6B4G is basically a 2A3 with a different base and a 6 volt filament, plain and simple. Sort of the American answer to the PX4. These monoblocks were obviously built on Magnavox chassis, probably from the big top of the line 128e, with quality 1950’s iron. As I’ve said previously, I’ll always choose a new amp made with vintage parts over a new amp built with all new components.

This one was advertised as being built by “the guys at Vacuum Tube Valley”. For those of you who aren’t familiar, VTV was a magazine circa 1999-2001 that ran for a few years and featured articles on tube amp circuits, how to build tube amps and amazing in-depth analysis of tube types. In short, it's the Bible, and it can be viewed in its entirety here: VTV. I own the first 12 issues and always enjoy looking through the magazines. Charles Kittelson was the publisher and editor, and I thought, perhaps the builder of these monos.

Hooking these up for the first time, not knowing what to expect, I was immediately blown away by the sheer power and force of 12 or so watts of triode power. After listening to so many amplifiers over the years, I know in the first few seconds if its good for me or not, and these were immediately a hit. Buying amps like this, its always the same week or more of anticipation while it ships…was the seller accurate in their description, will it arrive intact, will the expensive tubes be dust on arrival, will it hum like a monster, will it even work at all? Will it catch fire? “Will it sound good” almost takes a back seat. And quite frankly, in amps that look like these one does has to wonder.

So it was with great satisfaction that these hooked up fine, and ran without issue. Push pull amps in my experience generally have a slightly reserved character in comparison with single ended, the one major fault of push pull for me, but that was not in evidence here. These sound like big and powerful single ended amps. They capture the depth and space, the ethereal liveliness, in a way that single ended amps do. And that is about my highest compliment for a push pull amp.

Cool monos! You've just got to love dual rectifiers, in this case GE 5R4.

These old console amps are ripe for builds lke this. So many good parts just waiting for a second life.

Now this is a special tube that many have not heard of. Tung Sol made a super version of the 6SL7 in the 1950's, the 6SU7. This is a superior low-noise version that is very rare and desireable now.

The 6B4G as a push pull is a great platform. To my knowledge, Sovtek is the only company still making this tube.

I like the heavy duty switches and jeweled pilot lights used on the older gear. Good stuff!

I dont normally show the guts, but as these had no bottom plates it makes sense to include a shot. Look at how simple this push pull amp is. Only a few components, a few connections. Simplicity is the ultimate sophistication.

They do look the business. I only wish the input connections were in the back.

Overall, these are quite nice amps and very good performers. There is a view of my George Merrill GEM Dandy poly table in the background. That is HIGHLY recommended as well.