Here is some first hand info I'd like to share:
I like Sophia's Princess meshes or more accurately, "perforated plates" :-).
I have them plus some EML solid, KR and WE's. I would love to try the EML "true" meshes but was also warned to be careful of what amp I put them in.
I have never had a problem with the Sophias in my other 300b amps (Art Audio Symphony II and a custom one). I recently got some new Cary 300b monoblocks. They came with their own Cary branded/made to their spec 300b's which are mesh/perforated. No problem with their tubes in their amp. When I rolled the Sophias, within 5 minutes I had a orange spot developing on the plates. These particular Cary's run the tube real hard and you can't adjust it. Over 400 volts and 80 mA of current. Yeah, that gets you around 15 watts out of a 300b but at what price? Way shorter lifespan for sure and I don't think they sounded as good as my 7 watt and 10 watt 300b amps (those run in the 300's voltage wise, and maybe 50-60 mA's). I had a tech add a resistor to the Cary's to drop the bias down to 65 mA and the Sophias still developed an orange spot. The Cary's are now gone.
To someone interested in meshes, I would recommend contacting the maker of your 300b amp and asking them what voltage and current they are running the tube at. Even though a solid plate can dissapate more heat, it will have a shorter life if it's ran hard. Short of finding out those specs, I would guess you would be safe with the meshes if the amp is rated at less than 10 wpc and safer yet, 7 wpc. Hope this helped.
