Abraxas Audio -- Jeff Larson's "Darling Killer"

Here we have an incredibly unusual amplifier, a single ended 6350 by Jeff Larson of Abraxas Audio! This is Jeff’s “Darling Killer”, basically a single ended 12AU7 power amplifier. Forget about preamp duty, here we have an industrial 12AU7 cranking it out as the power tube! How cool is that?

Preamp-tube power amps are a special beast for sure. I previously owned a 6SN7 power amp by Jeremy Fix and found it to be extraordinarily detailed and with a huge and vibrant soundstage that rivals most of what I have owned before or since. This is in the same vein, but not quite as sweet sounding as the 6SN7. This is what a 12AU7 actually sounds like on its own; clean, clear and fast.

When an amp like this comes through I have to pause and behold. This is an amp unlike anything else out there. Minimalist by most anyone’s definition, and yet this little amp’s fidelity is very sweet. Yes, one or another of the big dollar amps do a few thing better than this, but they should at their price. This simple little amp cuts through all of the fog and delivers supreme sound at a very modest parts and price point.

Making somewhere south of 1 watt per channel, this is low power on the scale of the Darling 1626 or the 71a. The Abraxus 6350 “Darling Killer” sounds great even on my 94 db/wm Coral Flat 5. Hhaving a slightly smaller sound stage than some of my other amps, this one does still sound big and live, it has very good tone and a lot of definition and detail retrieval. There is no mistaking that this is a single ended amplifier! This is quiet amp, there is only the very slightest hum at idle with my ear near the (95 db/wm) speaker cone. This amp has a very clean and clear sound, not overly warm but not cold either. There is a lot to like about the small bit of power that this little gem makes.

In memory comparison to the Darling amps I have had, this is a more clinical sounding amplifier. The Darlings tend to be very clean and clear as well, but they are warmer and rounder. This amp is sharper, probably more detailed, but still pleasant. It would be very interesting to do a back to back with a good Darling build. Next to the Yamamoto 2A3, the Yamamoto does almost everything a bit better as would be expected, but going back to the 6350 there is a clearly different flavor that is still quite engaging. I don't currently have a single ended EL84 amplifier to test back and forth with but I think the sound is more similar than not. Overall though, I think this one has a sound signature that is all its own.

I’ve never owned one of Jeff Larson’s Abraxas creations before but have admired them for years. Jeff used some really unusual tubes and ripped the envelope wide open with his builds, and this one is no exception. This is a small but well put together amplifier that is unique in just about every way, and is super pleasing to listen to. I don't think Jeff Larson is still building amps, and I have not heard anything about him in quite some time. Here’s hoping he is doing well. There are are a few of Jeff’s amps still out there, and they occasionally come up for sale. Based on this one I would expect them to be quite good. Highly recommended.

A simple high-quality amplifier.

This build uses the 6FQ7/6CG7 triode as the driver tube. I’ve upgraded to RCA clear top versions that have proven to be non-microphonic and seem to sound great as clear tops usually do.

Rectified by the 5Y3, always a great choice.

The 6350 is an overbuilt, industrial version of the 12AU7 with a different pinout, and were made almost exclusively for 1950’s era computers. I think GE and Sylvania were the only ones to manufacture this tube, although they can be found with lots of different branding marks. These are reported to be very reliable and high quality tubes, as the massive computers they were used in made the tubes difficult and expensive to access. Tube failure was not an option.

Nice quality cloth lead vintage output transformers of unknown make.

This amp uses a 5Y3 rectifier, so of course I had to try an 80 globe on an adapter. Sublime!

Here it is in my living room system; its diminutive "almost 1 watt" pushing out music through my Zenith baffles in a pretty good-sized room. It sounds great; full and live at a real-world conversational volume. With the attenuator all the way to 11 this little amp makes it loud enough to be hard to talk over, and its still clean at its 100% mark. This is a very nice alternative to the EL84 push pull sound I've grown so fond of in this space.