I did find info on both that claimed 10K life. And looking at pictures of both with round getters and gold pins they looked the same. It's my favorite center position signal tube in my ST-70. The difference between an old stock e80cc and a 12au7 is very noticeable.I Never thought there was any difference. But i thought it meant tubes designed for 10K hours life span along with other manufacturing considerations depending on customer requirements.
They both claim very quiet, rugged, long life, etc. Eh, who knows.one is "pretty quiet" the other is "super quiet"
or I really have no idea.
Thus the rare and über-expensive "FQ" series.one is "pretty quiet" the other is "super quiet"
or I really have no idea.
It maybe PQ is an Amperex trademark. There was a time when the tube makers decided to have special tubes for critical applications. GE "5 star", RCA "Command", Sylvania "Gold brand", Mullard 10M. But i can't recall which maker uses SQ, it might be Amperex , too.I bought a Amperex gold pin "PQ" E80CC to replace one that had one side short out. I also noticed an "SQ" version. Anyone know the difference between the special quality and the premium quality?
Ya, I found both on Amprex branded tubes. Made by Philips, I tnink. Tunsgram was the other manufacturer of the e80cc originally. Then rebranded by others like Valvo, etc.It maybe PQ is an Amperex trademark. There was a time when the tube makers decided to have special tubes for critical applications. GE "5 star", RCA "Command", Sylvania "Gold brand", Mullard 10M. But i can't recall which maker uses SQ, it might be Amperex , too.
Both I've bought were tested and triode matched. The first one I paid very little for. I agree they have shot way up in price. But for whatever reason, they just sound right to me in my st70 with 12bh7's on each side. Some really like the 12bh7 in the center, but they sound a bit thin to me.Considering how bad every one of these that I have found is ( used or NOS) I came to the conclusion that PQ is Pitiful Quality and that SQ is Shi**y Quality.
Just my own experiences of a few dozens of these types,and I just don't get the hype OR the price
My recommendation: Test before buying.
Both I've bought were tested and triode matched. The first one I paid very little for. I agree they have shot way up in price. But for whatever reason, they just sound right to me in my st70 with 12bh7's on each side. Some really like the 12bh7 in the center, but they sound a bit thin to me.
We're you using them in a guitar amp?
Thus the rare and über-expensive "FQ" series.
Thanks! That explains it. I noticed the Amperex were acually Philip's when doing my search. The first one I had was a Tunsgram branded Siemens with a D better. This one is a bit taller with a halo better at the top and gold pins.The difference is marketing.
No practical difference exists between PQ and SQ:
Amperex PQ = Premium QualitySo this is the same tube, just different marketing nomenclature for Europe vs. USA. In the US "special" wasn't as powerful a term as "PREMIUM".
Philips SQ = Special Quality
The PQ/SQ tubes were designed and manufactured to better standards than ordinary tubes: more rigid supports to be less microphonic and extend lifespan; better getters to reduce gas, increase performance, and extend lifespan; better heater construction to reduce hum and extend the filament's lifespan; and a more expensive internal construction, including the spacers. Well, it's complicated than this, as Philips tended to rebrand tubes, as did Amperex, so the tubes might have been made by an entirely different vendor. (shrug)
I have a handful of PQ tubes in a 1960s reel-to-reel I was gifted. (Most of those R2Rs are stripped for the PQ tubes and then the rest of the unit is discarded.) It makes sense that in a vibration-prone environment such tubes would have greater benefit. But for typical audio use? Probably no difference from any other tube in its class. The demand is likely just the mystique of using a "premium" or "special" tube.
Phillips couldn't sell under their own name in the US because it was too similar sounding to Philco. Or so I've heard at least. They bought out Amperex for the name, but they also sold things under the Norelco brand. Maybe they didn't want to associate tubes and electric razors though.
i like my PQ's better then my SQ's mostly because i paid more the PQ's and it makes feel better about spending more on them