Here's a pic of a W. E. VT-52. It's a DHT similar to a 45. The differences are a taller bottle, 6.3 (or 7V depending on who you believe) filament and possibly a greater plate dissipation. There's a little bit out there on private web pages on this tube but very little agreement about the ratings. They are said to sound very good. If the characteristics are similar to a 45 then it should be used with a SE OPT of around 4K - 6K Pri Z. Many of the schematics published for the tube show an OPT with a 2K5 primary, which seems to me too low for a tube with an Rp twice that of a 2A3. I plan to fool with this and if I like the results might look around for another one. I already have a good SE 45 amp that is my best sounding SE amp. I built it 6 years ago and could do lots better now. Got to add this one to the Big List Of Projects.

there are folks that swear by VT-52s. There's a whole site didicated to them for DIYers.
try:
www.vt52.com

I thought VT-52 was kinda close to an 801/10Y, but never had a reason to really learn. I know a guy with a bunch of WE ones, but I can't shake 'em loose. So there's another one I have to outlive. ;)

Originally posted by tubino
I thought VT-52 was kinda close to an 801/10Y, but never had a reason to really learn. I know a guy with a bunch of WE ones, but I can't shake 'em loose. So there's another one I have to outlive. ;)

Perhaps you are thinking of the VT-25, which is a 10/10Y tube.
The VT-52 is closer to a 45-not that hard to get really. Tubeworld has some.
10/10Y/801s are a whole other ball of wax.

Thanks for the correction.

I thought a VT-52 was a CRT computer terminal from DEC (that's the late and unlamented Digital Equipment Corp., for you non New Englanders) :-)

I'm interested to see what kind of circuit can be derived from this VT-52...should definately make an intriging SE amp with a pair!

Originally posted by jt1stcav
I'm interested to see what kind of circuit can be derived from this VT-52...should definately make an intriging SE amp with a pair!


Well, it's like any low mu DHT, and especially like the 45. It takes about 35VRMS or so to drive it to full output and the Miller capacitance isn't too bad so that leaves a lot of driver options. I'm partial to the 6AQ8 in my bench tests lately so maybe I'll try a permanent installation with that one. The plate voltage is pretty low so a direct coupled amp can be constructed without exceeding 600VDC B+ supply, the practical limit of easily acquired filter caps. I like 2-stage circuits. The one SE amp that I have that has never sounded as good as it should uses three stages and a SRPP driver. My best one is two stages and a plain anode loaded driver so I'll go in tha tdirection. I have found that direct coupling the driver to the power tube grid will give a couple of dbs of headroom if the driver will push the power tube grid positive without distorting too much. I scribbled up a schenatic along these lines on my lunch hour yesterday on a tiny notepad. Here it is below with a 76 or 56 tube or 6P5 driver. You could add bootstrapping between the VT-52 cathode and the driver's 450VDC plate supply node. I have tried this and just got more LF distortion along with a little more bass but some people like it.
Another option that I like the sound of in experiments is what Jack Elliano of Electra-Print calls "Direct Reactance": a direct coupled driver with a choke load taking its supply voltage from the output tube's cathode resistance. I'd better draw that, as it makes no sense to describe it.

But you get the idea...