Amperex PQ 6922 vs Amperex PQ 7308

PQ and Non-PQ are the same tube. I've not heard consistant differences in sound between the two label types.

On the otherhand, in the gear I've owned, Amperex 6922 and 7308 sound quite different from one another. There is also a difference (in sound) between Holland and USA product with the same internal construction.

I've owned/tried approx. 100 various Amperex White label 6922's and 7308's in Audion and Consonance gear.

Same goes for Philips SQ and Non-SQ labels (based on sampling 20+ of their 6922's). They sound alike.

Talon:

In general the Holland 6922's and 7308's are a bit softer sounding than their USA counterparts.

I usually prefer softer sounding 6922 types, but I ended up keeping only USA versions for personal use (so there are other subtle differences which I am unable to describe well).

I've read that PQ's were screened for close section match, but as mentioned I've never detected a difference between the PQ/Non-PQ versions I've gone through. I have both types sharing the same production/date codes (they are the same tubes).

JAN/USN, etc., were marked such for military purchase orders (same as tubes being marked IBM for IBM PO's, Fisher by Mullard, Telefunken tubes marked Pilot Radio Corp., etc.).

In all the gear I've used White label 6922's have fuller bass/mid-bass than White label 7308's. The 7308's have greater HF extension than the 6922. My preference is dependent upon the system they are being used in.

Never tried 7308's in a phono section.