"Full music" 205D Tubes

[Hollow Fate]

I bought four beautiful looking tubes from an Ebay auction clearing house as a “Buy it Now” several days ago and received them recently. I did some Web searching and reading before I hit the “Buy Button”. The tubes are labelled 205D and are scripted as “Full music” on the bases but have no other designators or boxes. They look absolutely new but until I figure out how to properly test them the jury is out. Once again I seek the assistance of this forum.

My research on the Web to date pretty much confirms that they were made in the Tianjin (TJ) China factory. For those who might like to know, the Tianjin factory specializes in making copies of some of the earliest American (Western Electric) tubes like 300B’s and as it turns out 205D’s amongst others. As an aside; the US military VT designation for the 205D is “VT-2” making it a very old design. My reading suggests 1918. I cannot find anything picture-wise on the Web that looks exactly like these tubes of mine though. They are solid black plate, black base tubes but with top pips and the whole look of these tubes says Tianjin although they were listed and sold to me as RCA’s. I disagree with this part of the description, but no complaints just the same. I paid $32 each and the US/Euro sites are quoting $170 - 200 each for TJ's. But are they any good is the question?

I read that a particular amp out there (the Bugle design http://www.the-planet.org/Ragtop.html and http://www.wavelengthaudio.com/bugle.pdf ) can use both 300B’s and 205D’s in the same slot. With this in mind my tube tester was set up for 300B’s but I changed the filament heater setting to 4.5 volts from 5 volts. Well the first good news is that no shorts and no leakage were detected but I have no way to know where to position the “Plate” dial. The tester is a Heathkit IT-17 Emission unit. Any guidance would be appreciated. When I swing the “Plate” switch higher the “Line/Test” needle swings to follow, if this helps.

One last thing. One of my future projects involves using either #27 or #76 tubes in a pre-amp configuration. To this end I purchased at the same time as the aforementioned 205D’s, a quad of Arcturus 127 (ie: #27) tubes. I love the look of these tubes. I already have a few but it’s not just the blue glass (even my girlfriend thinks they look great) but the internal construction of many early 27’s is something to marvel at. I mean really; glass bar insulators hanging in the vacuum space. Tr?s cool. Anywho, after testing the four tubes, three read 100% and one read 70%. One of the 100% tubes shows a “leak” but this appears on and off. (Leak. No leak.) The question is, how does such a thing actually translate into music at the speakers? Can we hear it? Maybe hear it? Any info here is appreciated. It’s not a real concern to me if you deliver a downside answer as I have both extra Arcturus 27’s and other 27’s to fit the project if needed.
Merry Christmas to all.

Donald.

[mesherm]

http://www.acoustic-dimension.com/fullmusic/specs.htm
http://www.acoustic-dimension.com/fullm ... lmusic.htm

[sorenj07]

http://www.mif.pg.gda.pl/homepages/fran ... 2/205D.gif


and some curves for your use

http://www.mif.pg.gda.pl/homepages/fran ... 2/205D.pdf

maybe use it as a phase splitter/driver for 300B's?

[TomMcNally]

Hi Donald -

I see the genuine WE tubes brought $ 1695.00 a pair on eBay recently ! Typically, WE tubes were never second sourced back in the day, so yours are probably Full Music brand. Personally, I would skip the tube tester and build a amp and see how they sound. Tube testers don't tell the full story, since they don't apply real world conditions. The inexpensive ones were basically designed for TV repairmen to sell tubes.

... tom

[Hollow Fate]

Many thanks for the 205D tube links and Tom’s suggestion to just build an amp and listen. I’ve only built two tube amps so far but I’m starting to realise something. Even though transformers and quality passive components can be pricey, they are also “recyclable” into other projects if things don’t work out how you might expect them to. This has been a bit of a revelation to me. In the past, committing to a project with high-end components that might lead to a costly embarrassment gave me pause. Now I feel that any potential shortcomings in a new project are part of the learning curve. It is better to jump in and just go for it. I might have to re-configure things later (if things don’t work out) but so be it.

So for now the 205D’s will be put safely away as there are two amp projects that precede them. Just the same I’m happy I’ve acquired them. When they finally end up in an amp I’ll revisit this thread. Thanks to all.

Donald.

[EWBrown]

TJ and Sophia both make excellent reproductions of many of the classic "old school" tubes, and some of their own variants, including a double-capacity version of a 300B from Sophia. This tube is taller, the plate (and other elements) are twice as long.

Gary's amp is based on Gordon Rankin's "Bugle 45", with added components and tube sockets in order to allow some interesting tube-swapping. He can run 45s, 46,s, 205Ds, 300Bs and 2A3s. I;ve heard this amp in action, with the 205Ds, truly wonderful sounding...

I'm building up a 300B version, into an ST70 chassis, which is now about 50% complete, just waiting on some free time to finish it up...

/ed B in NH