6922 recommendations for ARC PH7

the ’sq’ designation on old stock philips/amperex tubes was a labelling signifying highly screened tubes, with linear, strong gain and quietness of operation -- sq stands for ’special quality’, thus sold as premium tubes

it is NOT a location of manufacture designation...

Philips had factories everywhere.
Holland made tubes, were branded as Philips, Philips Miniwatt, Amperex, Dario, RT, Mazda...and having the triangle sign etched at bottom of tube, including tube type and manufacturing dates, noted that they were manufactured at Heerlen factory in Holland. All were the same tube, having the SQ logo or not. In fact some Holland made ones, were branded Amperex, had the PQ logo, that was used for the ones made in USA and having the * sign etched instead.
India made tubes under licence for Mullard, BEL factory same tooling, different etched codes.
So to be sure always check what the etched codes are for finding out which factory they were coming from.

Totally agree. I was not saying the “sq” designated where they were made. I was abbreviating the tube name in that post.  Sorry for the confusion. The one poster recommended I go out and buy the “Amprex tube ASAP”.  My point was that the Amprex 6922 and the Phillips SQ are the same tube of which I have already purchased. 

the key to understanding tube production and sales is to understand that there were unavoidable and significant variances in how the innards of any tube (but especially a small signal tube) were assembled, thus affecting their performance ... (of course back in those days, vacuum tubes were absolutely essential components in equipment much more important than hifi gear making music... so great pains were taken to make good ones with pure materials and extremely careful assembly)

thus it was the screening and testing of tubes that made all the difference...that is why tubes were graded and sorted and branded/marked as such, many many portions of lots were rejected or sold off brand

as time has passed, 40-50-60 years go by, old tube supply doesn’t expand (garage and dusty warehouse finds are possible, but so rare nowadays), yet tubes are in use every day, thus making the need to test, confirm function, quietness etc etc is as important as ever if one is going to spend some real money on ’nos’ or used old stock tubes

@barnettk, you will be amazed of the sound difference between a Holland E88CC and a 6922 USA, same year, both made with sane tooling.
For sure both are good tubes but my preference are the Dutch ones for a single reason. They do not become noisy so quickly compared to their USA cousins. 
@jjss49 i totally agree that tubes are not created equally and testing is required for all these old tubes.