Amperex PQ 6922 vs Amperex PQ 7308

Joe's Tube Lore mentions Amperex 7308, but not "PQ"
specifically, although Joe mentions "shield" in his description
of the 7308, which sounds to me like the "PQ" shield printed
on the tube. It's my understanding that Amperex 7308 PQ are the only
version of the 7308, but I could be wrong (somebody please correct me
if I am). Essentially, the 7308 tubes are the premium, long life versions
of the 6922 tubes, and therefore are "Premium Quality" by
default. Make sense?

Here's what Joe's Tube Lore says about the Amperex 7308:
"Amperex 7308 white label, US (shield, gold pins) My favorite
7308 by a small margin. Bass is a bit better than the Holland 6922s.
Vocals lack just a touch of body compared to the best Amperex 6DJ8s &
6922s. Still a very good tube overall..."

I have tried both the 7308 and 6922 PQ and prefer the 6922 PQ.

Amperex made a "regular" and a PQ version of the 7308 tube. I have a pair of each. The PQ version seems a little more extended at the frequency extremes, whereas the regular versions are more "midrangey"/"tubey".

Hope that helps.

Nhtran, do you think Joe's mention of the "shield" in his description of the Amperex 7308 refers the a "PQ" shield? Did the regular Amperex 7308 you owned have a shield printed on the tube?

There was also a military version of the 7308, no shield or PQ.

That said, if anyone is in need of some white or orange label Amperex 7308 PQ USA made I have a couple pairs I could part with. Also a single D-getter white label holland tube.

I've compared to a bunch of 6DJ8s (which are nice, and a lot more common), both are good but I'd rate the 7308 a fair bit higher.

-Ed

So, Ed, explain the difference between the "shield" and the "PQ". I've seen PQ tubes, but I don't know what to look for with the "shield" imprinted tubes.