It has a push pull cathode follower circuit for the output with a power transformer standing in for the output transformer . I'm really curious to see just how well this thing works. Has anyone actually put one of these together and had any success?
Ed

The cathode follower part is a lot like a Macintosh amp circuit . Is the a parts list with the circuit , it looks like they may be using a UTC power transformer as the output transformer .

Sorry, the article didn't come with a parts list, just what you see from the schematic.
Ed

A lot of the LS series transformers were toroidal wound even the power transformers http://www.bunkerofdoom.com/xfm/UTC_1949/UTC49.pdf

Mox nix.

Layouts for "novel amplifiers" abounded through the fifties as one person after another tried to reinvent the wheel.

In my book, they aren't worth bothering with. None of them will generate any improvements in performance worth mentioning, even to those who fancy that their ears came from the elfin clan. KISS and save your efforts for more rewarding enterprises.

Larry

Probably the best amplifier circuit of the 1950s was the Williamson/Ultra Linear design. A lot of them were made, and they did work well. You could easily build one today, with the cost of the transformers being the major obstacle.

The Williamson is no novelty circuit. It became a standard. Frankly, it became the wheel that the others were trying to re-invent.

Larry

Exactly my point; if you want to build a "retro" hi-fi amplifier, that is the one.

The reason this one cought my eye is the use of a power transformer for the output transformer. I have a lot of power transformer iron but not output. Don't want to spend a lot for transformers.
Ed

Well then, let's cut to the chase.

This circuit should work, after a fashion (don't be surprised if you discover that the predicted results are somewhat exaggerated). It'll give you sound, after a fashion. Whether or not you'll like that sound is another matter altogether, and you're the only one who can answer that question.

I personally wouldn't waste my time trying to find out, because I don't like the odds I see. But those are odds from my perspective and not yours; the time and effort are yours to expend.

Larry

I'm not sure they ever tried it. With more or less instant-on B+ from the 5Y3 and delayed bias from the 6X5, I'd expect a blown fuse on every power-up.

Dave

I'd bet the 6X5 heats up faster than a 6L6, so it will likely work fine.

That's unless the 6X5 shorts, which was all too common

You're right, I had a "short between the earphones" and forgot that the 6L6 had to warm up too!

Dave

Agree... I built one last year, superb! However, you need to check the VLF stability, a congenital Williamson weakness. I put in "VLF shelf" circuits (one in each driver grid from the phase splitter) to cut the tendency to surge at one or two Hz due to the three phase leads in the design (the third one being the OPT.)
Google "VLF shelf" circuit "williamson"... many hits, including from me!
Cheers,
Roger

A perfect example of why they should not allow napkins and pencils in bars.

- Leigh