Don Allen SE 6550 / KT88

Don Allen is an underground legend in the hifi tube amp world. His classic builds and reputation for supreme sounding amplifiers have graced many an audio forum for two decades or more. Don built a fair number of amps before his death, from small single ended EL-84 amps built onto upside down tin cake pans, up to monstrously large multi transformer push pull 2A3 monoblocks. One feature that always seems to go with Don’s amps is the signature backlit silver lightning bolt that usually graced the front panel; a Las Vegas like tribute to good sound.

Don Allen owned a TV repair shop in Phoenix Arizona, and in his spare time he built a variety of tube amplifiers, both single ended and push pull. He sold mostly locally and was revered for hosting “well fed” listening parties where local Phoenix audio folks gathered and listened to his newest gear, gave their opinions, and helped Don narrow things down until it “spoke to God”. I wish I could have attended one of those evenings! Parts ran the gamut in Don’s amps; from ultra expensive to generic and pedestrian, whatever sounded the best was chosen. I really respect that way of working and I think it reflects a good sense of what is important and what isn’t. Flashy and expensive doesn't always equal best, and sometimes it's the simple part that is the most appropriate choice.

I’ve been on the lookout for one of Don’s amps for a while, but there just aren’t that many of them and they don't come up for sale very often. Don died a few years ago, and now we are left to wait for one of his fine amps to come up on the used marketplace. Eventually, the Universe always provides, and so is the case here. Below is what I think is one of Don’s finest builds, a single ended KT88/6550 which I am told was Don’s personal amplifier and the last amp he sold. The person I bought it from purchased it directly from Don in his Phoenix home in 2014.

This one has some of the largest output and power transformers that I have ever seen and weighs in around 45 pounds. Putting out roughly 10 watts per channel, this amplifier sounds very authoritative, with great presence and effortless drive. It is almost completely silent at idle which is always a nice feature. It images very big and has that wonderful sense of space and placement that make single ended amplifiers so much fun to listen to. Clarity is through the roof. And with 10 watts per channel it can push a wide variety of speakers, making it easy to live with in the real world. No need for high efficiency speakers, this amp will effectively drive a wide array of speakers. I’ve run a number of tubes through this amp, and this sounded best to me with the new production Tung Sol KT120 tubes, but also ran old stock Tung Sol 6550 pretty damn well. Strangely my fancy GEC TT21 were not my first choice, which had been my expectation. You never really know, but the proof is hard to disagree with. The TT21 sounded good, but didn't have the presence and drive of the KT120. The KT120 make this amp jump up and dance.

Sadly, so many of the greats are no longer with us and Don is another whom I missed meeting. He left a strong legacy of fine audio behind, and the amps he built will be enjoyed by enthusiasts for a long time to come. One of Don’s friends has created a tribute page to Don on Facebook, linked here. I am not a Facebook participant, but if you are please have a look and contribute a memory if you have one.

Don Allen's lighting bolt amps are a solid choice in tube audio, and in this case at least, will put to shame some pretty high dollar fancy looking gear. Don’s understated simple black chassis amps are not to be missed. Highly recommended.

Clean and simple, a very classic tube power amplifier aesthetic. Most of Don's amps seem to have been built on a basic chassis like this, usually painted Henry Ford black. I like the look, and of course the lightning bolt (backlit when running), makes this a signature Don Allen build, immediately recognizable.

6BZ8 is an unusual, and quite affordable, choice for the driver tube. A new one for me, they seem to do their job, as this amp sounds excellent.

Here with vintage Tung Sol 6550 tubes.

This is a big amplifier! Weighing in around 45 pounds, the footprint is 17x14. Again I've broken my promise not to buy any more giant amplifiers! Moving this one in and out of the system is a bit of a chore, and that will be its undoing for me.

Look at the size of those Hammond output transformers. They dwarf the Tung Sol 6550 tubes.

The lightning bolt is classic Don Allen and serves as his signature on this amplifier.

Basic but solid quality connectors. No frills, but no BS either.

Shazam! I love the lightening bolt! This feels very Las Vegas to me, and you know instantly that this is a Don Allen build.

Here with vintage 1960's GEC TT21 tubes. The TT21 is an industrial KT88 with a top cap, so you need an adapter to use them in a KT88 amplifier but they can sometimes be found cheaper than the standard GEC KT88. Much like the 807 to the 6L6.

Here it is with the big Tung Sol KT120 tubes. These sound really good in this amp, pretty much the best so far.