So most likely not a tube issue then???
Well, I think the 5670 that you measured has lower than average transconductance. IIRC, someone else had a similar problem with a WE tube. At that time I speculated their tube might be used with an exhausted cathode coating, but it might be that the WE does not match the GE 5670 whose curves I used in the design - similar but not identical parameters. The only way to tell would be a transconductance tube tester; until then we are just speculating.
Hey Paul, when I try and swap this tube at THETUBESTORE what exactly do I need to make sure is matched?? Dos this mean one of the tubes is bad or just not matched to the other??
I'm sorry, I don't know a good answer. You could just say that the tube won't bias up properly in your Paramount V1.1 (be sure to tell them what other tubes you have that do bias up properly. They have a good reputation and might exchange it on that basis. What we don't know is whether the transconductance is actually below spec, or within spec but on the low side.
I checked their web site, and they say "Our current stock of the Western Electric 396A tube is used. All test great and are guaranteed." That suggests they did test the tube before it was shipped, but of course used tubes may well have reduced transconductance.
If necessary we can reduce the tube current a bit to bring the voltage within the adjustment range - I'd hate to see you stuck with a tube that won't work.
As a matter of interest, the 396 was the very first 9-pin tube made. I have a pdf of the 1947 article in the Bell Labs magazine; it's just a hair too big to attach but if you ping me I'll email it.
