Any experience with Tube rolling 6922 for Conrad Johnson preamp?


I am running the stock 6922 in my Conrad Johnson ET7 series 1 preamp.  (If you are not familiar, the preamp uses a single 6922).  My dealer won’t discuss other tubes, encouraging me to only buy from CJ.

wondering if anyone can share their experiences rolling the 6922 in an ET7, other ET series, or even older CJ preamps.  Also wondering what brand of tubes CJ uses as stock - I have not yet removed the cover to see.

have created wonderful improvements with NOS tubes in other equipment, hoping to do the same here with the 6922.  Full disclosure-I have also laid some eggs, too.  Very expensive eggs.
meiatflask
c-j preamps used to be really hard on tubes. They had 29 dbs of gain which required that the tubes be driven hard. Driving the tubes hard makes them go noisy quickly. I see the ET 7 has 25 dbs of gain which is better but still probably not easy on the tube.

I suggest you talk to Kevin Deal at Upscale Audio. He will tell you which tubes can handle the punishment your pre dishes out.

Kevin is a controversial guy, some like him, others don't. I hope we don’t have that debate again. You will be clear about what he thinks after you talk to him. You can decide for yourself whether you want to do business with him. One 6922 won’t be big money by Audiogon standards, so I say give him a try.
I have an email into Upscale.  I have purchased mullards NOS 12au7s for an amp based upon their recommendation and was very happy.  curious if he recommends the matsushita/national that dill suggested above.
AI second that. I haven`t tried the ET series preamps, but the ET 250 S has 2 driver 6922/6DJ8/Ecc 88 tubes. They wear out after about 1000 hours. 
That said, the best sound I have had was with a pair of Mullard Ecc 88s.

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

The Telefunken's (6922/Ecc88) sound the best to me, followed by the Siemens 6922.  The Telefunken is from 1967; the Siemens from 1972 +/-.  They both offer far better dynamics than the OEM EH tubes. 

I can't figure it out--$10,000 or more for a preamp, and a $29.00 crappy sounding tube in the box.