Conrad Johnson Premier 140 6922 tube swapping

I had one of these--great sounding amp but mine was problematic--and rolled a few tubes in it. I even bought some vintage Tung-Sol 6550's which made an enormous difference, more than the 6922's. I thought the Siemens CCa was the best sounding 6922 variant but the Tungsram mentioned above is also good, as well as some Ediswans I bought at Upscale Audio.

My Premier 140 did indeed sound great, perhaps one of the best-sounding amps I have ever had. The problem it had, and perhaps it is not common, is that it kept blowing line and speaker fuses. I could easily and cheaply replace the speaker fueses but the line fuses was another matter--I had to keep sending it back to C-J to get it replaced since it voided the warranty. I ended up selling it for a song to a technician who was interested in working on it. Like I said, it may not have been a common problem.

I would try some inexpensive new production 6922 tubes that you can buy on the gon or ebay and see how much difference they make. If you like what you hear, almost any NOS Amperex, Mullard, Ediswan, Siemens, or Telefunken tube will be an upgrade in sound, or even a Tungsram. You can break the bank on NOS tubes but there are some out there that are a bargain. I have had black plate NOS Tung-Sol 6550's as well as the three-hole gray plate versions that are not quite as good as the very pricey and rare black plates, but either will be a serious upgrade over the stock new production tubes. The Philips 6550 is also great as is the GE 6550. There are probably also some good new production 6550's, KT-88's, and you might even be able to use KT-120's, but I would ask C-J if this is possible. Exactly which tubes are best will most likely be up to your own listening preferences.

My amp also had the upgraded PTFE caps but I bought it used with the upgrade already done, so I never heard the standard caps. This is probably a worthwhile upgrade.