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
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.
I pushed them all around while tube rolling.  These tubes can be readily aquired at reasonable costs.  
When rolling, I use to make a note card detailing each tube.  Let your ears judge each.
The response from Upscale Audio:

“As we're not a Conrad Johnson dealer, we just don't have enough information on their units to be able to answer your questions. You would have to contact the manufacturer or a CJ dealer.
Best,Thom”


1- dill- at such a low price of $35, the matsushita/national seems like I can’t lose giving it a try, compared to the high price telefunken.  What other tubes have you listened to for comparison, and in which preamp?

2- have any of you suggesting the telefunken listened to the matsushita?

3-jampro - any issues using the 7 volt 7dj8 in a 6 volt system? Certainly these are much lower in cost that the 6 volt telefunken, but wondering if their is a compromise somewhere in the circuit.....

thoughts?

bill