PX25 operating points

[bcherry]

Thanks Frank

Re: Meshplates, I heard some old samples and they were excellent sounding but I don't have a clue as to why meshplates could be superior to the regular ones.

Is it akin to why a matte surface is a better collector of thermal energy than a shiny one - more surface area? Too bad we can't actually see what those electrons are doing on their journey from cathode to anode. I have a solid plate prototype of the PX25 before it went into production with meshplate, and the two sound nothing alike.

The Osram PX25 data sheet shows the original valve as having an ST bottle, but all the pictures and samples I've seen show balloon shape with different dimensions. Was there ever an ST PX25 Osram?

Brian

[fdegrove]

Hi,

The Osram PX25 data sheet shows the original valve as having an ST bottle, but all the pictures and samples I've seen show balloon shape with different dimensions. Was there ever an ST PX25 Osram?

Not that I'm aware of.

Anyone else?

Cheers,

[bcherry]

Actually the data sheet shows GT, not ST; my mistake.

But I posted the question in HKtubeaudio forum and got this interesting reply.

The data sheet show a "GT" type (with straight side) rather than "ST". To my knowledge, there is only globe and GT type PX25 from MOV/GEC and no ST type. And some amp (like some from Decca) can only use GT type PX25 as space allowed is very small. GT type PX25 is much cheaper compare to globe PX25.

On the contrary, PX4 has globe, ST, and GT types.

Tim

So, will be on the lookout for some "much cheaper" PX25 GT.

Brian