My only possible contribution to this thread is my opinion about the use of 6922 and PCC88/7DJ8 in my Audio Research LS7 and LS2.
In comparison to CJ preamps they offer less gain (LS7: 12dB, LS2: 18dB instead of CJ's 27dB e.g. of the Classic 2).
My first choice is Telefunken PCC88/7DJ8 as Telefunken ECC88/6DJ8 are far beyond payability. IMO nothing compares to the sparkling highs, the depth of soundstage and the reliability of Tellys.
Runner up: Tungsram `88 (both ECC and PCC). Close to Telefunken.
And Siemens E88CC - fine tubes, but a little noisy.
Third: Philips PCC88, but be carefull: These are available made in Heerenveen/Netherlands and German production (by Valvo/Hamburg.) They are easily to distinguish: German Valvo/Philips sport a symmetrical two-point pyramidal getter-holder, Dutch Philips a one-point rod instead. The Dutch Philips offer a refined, airy sound, the Valvo/Philips give more (but less defined) bass at the cost of a little lack of detail and resolution.
Worth a trial is the use of PCC189/7ES8. These tubes work very well in my LS2 and LS7. They are similar but not the same as 7DJ8 but do a very good job especially in preamps. I prefer these as tube no. 1 and 2 in my LS7. I found more coherence with these. But keep in mind that these types are no officially recommended replacement for the 6922/ECC88-family. Despite that they show great results in my preamps.
Jan
In comparison to CJ preamps they offer less gain (LS7: 12dB, LS2: 18dB instead of CJ's 27dB e.g. of the Classic 2).
My first choice is Telefunken PCC88/7DJ8 as Telefunken ECC88/6DJ8 are far beyond payability. IMO nothing compares to the sparkling highs, the depth of soundstage and the reliability of Tellys.
Runner up: Tungsram `88 (both ECC and PCC). Close to Telefunken.
And Siemens E88CC - fine tubes, but a little noisy.
Third: Philips PCC88, but be carefull: These are available made in Heerenveen/Netherlands and German production (by Valvo/Hamburg.) They are easily to distinguish: German Valvo/Philips sport a symmetrical two-point pyramidal getter-holder, Dutch Philips a one-point rod instead. The Dutch Philips offer a refined, airy sound, the Valvo/Philips give more (but less defined) bass at the cost of a little lack of detail and resolution.
Worth a trial is the use of PCC189/7ES8. These tubes work very well in my LS2 and LS7. They are similar but not the same as 7DJ8 but do a very good job especially in preamps. I prefer these as tube no. 1 and 2 in my LS7. I found more coherence with these. But keep in mind that these types are no officially recommended replacement for the 6922/ECC88-family. Despite that they show great results in my preamps.
Jan