New tubes for Conrad Johnson17LS Pre

I have the same preamp and I just did what you are thinking of doing. I searched all over the web and based on what I read decided to try out a set of Amprex white label gold pin 6922s. I was expecting more improvment than I heard. I would say I marginally prefer the Amprex to the EH tubes, probably not worth the trouble in my opinion. The guy who gave me the recomendation said it made a big difference, well I didn't hear it. I did change out some tubes in my Audiopax amps before this and it made a very big difference, so I know tube rolling can have some real positive effects, I just didn't hear it with the tubes I tried for my CJ 17LS. Most of the tubes I found for sale are used, and the price seemed to be about 2x higher if they were being sold as new.

Hi David12. To be candid here.... I have never heard your preamp in my own rig, however, I would like to point out that the typical 6922,6dj8 family of valves will traditionally last in excess of 3,000 to 4,000 hours of playing time in the CJ.Unless the tubes have become noisy or microphonic, I can't believe they would not test within spec for your preamp. NOS vrs current production tubes is a very subjective topic to be sure. One must also take into consideration the fact that almost all of the better modern tubed gear being manufactured today has been voiced with current production tubes. That is no guarantee the preamp will sound any better with good low noise NOS valves. In my experience: regardless of modern or vintage gear [preamps in particular],a strong testing low noise nos 6922 tube with tightly matched triode sections would inevitably win hands down in any given shoot out. Those that refuse to believe it are the people that [1] did a comparison with tired nos tubes [2]used nos tubes with poorly matched triode sections[3] used noisey or microphonic nos tubes [4] those that refuse to pay the current market value for a quiet and strong testing vintage Seimen,telefunken,Dutch Amperex[to name a few] 6922 family of tubes. Furthermore; sometimes the gain in sonics may not be justified given the ever increasing cost of good nos valves.I for one, believe the premium selected and matched Eh tubes are decent sounding in your preamp.... the russian military 6n23e's are considerably better [by a wide margin] and are always dead quiet to boot.They can be had for the same money with a little searching.I really like cellorover's anology with regards to establishing a benchmark for comparison. Do you have a tube tester? I would take bets that your stock tubes would test better than 90 percent. Perhaps, cellorover's suggestion of up grading to the mk2 version is in fact "the bigger bang for the buck". All the best in your journey.

Hi Ejlif. Did you test these used tubes you acquired?

Thanks for you're thoughtful suggestions guys. The CJ is a mark 1 version, but the tubes have only a few miles on the clock. I will follow the consensus and hang fire on the new tubes. I'm interested in the idea of upgrading to the mark 2, which I did'nt know you could do. I live in the UK which makes a trip back over the pond to CJ, risky and expensive.
A recent review of the mark 2 in the UK mag HiFi News, which I think is pretty good, suggested the mark 2 was different, not necessarily better than the mark 1. The change, it suggested was brought about by the need to use a different, perhaps more reliable capacitor. I have'nt compared the 2 pre's myself so could'nt comment. Thanks again for the helpful replies.
David

Hi David12,

I talked to CJ about upgrading my 17LS to the 17LS2. Like
you I was interested in this as well. Unfortunatley the
the quote I got was near $2K. Considering that the new
17LS2 costs only $500 more than the original its hard
to justify the cost. For what its worth the dealer I purchased my 17LS now has the 17LS2. According to him the difference is very subtle.

Hope this helps
Cmach