View Single Post
Old 25th May 2006, 09:44 PM
Paul Barker's Avatar
Paul Barker Paul Barker is offline
Senior Member
Join Date: Dec 2005
Location: Scarborough
Posts: 1,615
Default Re: Newbie guide to SE Vs PP

Dave, history of 2a3 started with 45. 45 is half a 2a3 in original form. They wanted more power than 45 but couldn't make a biggere more powerful valve so they stuck two 45 structures inside the same glass envelope parrallel connected it all out at the base. These are now known as dual plate 2a3's. Then they managed to obtain those characteristics reliably with a single structure, this became known as the mono plate 2a3. These type of valves were commonall garden table top radio valves.

I think 300b, which is a souped up version of the above was aimed at the bigger commercial sector like theatres, Westeren Electric theatre amps.

In the UK Western Elec are known as STC (Standard Comunication and cables). All WE valves are available as stc equivalents with a prefix 4 to the number.

List member Darren D had a pair of STC 4300a's. These are the forrunners of the 300b, the Japanese pay an absolute fortune for this valve. Darren and I played them, they were quite good, but give me a balloon px25 any day.

300b's often got used as series pass regulators because of reliability.

45's used by US military as fuses.

45's are still very available very cheap, go figure. They sound better than 2a3 and 300b, but power output limited.

Cheapest route into this is the 6.3v variants of 2a3 structure, 6a3 and 6b4g (IO base). Also Svetlana 2a3 is a bargain.

British similarr valve is px4, Europian Ad1, both mono plates. Indirectly heated version 6a5g, r120, will cost you more than a dht version because of rarity, sound very good I have two 6a5g's, wouldn't part with.

We made the 300b as a 4300.

Our px25 has not been copied, it isn't like a 300b in any way shape or form.

Mesh plate valves have always been made, and do sound better. The Chinease and others have cottoned onto this they make current production punched sheet metal anode valves to try and emulate the mesh plate. They call it a mesh plate. These do generally sound quite good, but are more expensive.

There's a little history of useable dht's. There are lower powered ones, and higher powered ones but those are the common useful range ones.
Reply With Quote