Conrad Johnson Premier 140 6922 tube swapping

I'm not sure what design flaws you're referring to. I think that Johnsonwu meant that since the amp is an older model that the capacitors and resistors might need to be replaced.

I don't know how many years they are good for, but I suggest you find out how old the amp you are looking at is and get an estimate of the hours it has on it and give c-j a call. They could tell you how long you could expect to use the amp before it needs any maintenance.

c-j uses quality parts, especially in its Premier line, so the parts should last as long as those in any other make of amp, except maybe Bryston with their 20 year warranty.

I'm not an expert, but from what I know the amp is a very good one and has no design flaws that need to be corrected. People like to tube roll and try other tweaks to tailor the sound to their own tastes, but that is not necessary. I'm sure many owners like the amp with the stock tubes.

If that doesn't answer your question, give us a little more information about the design flaws you're concerned about.

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.

Repuluso....That amp had issues as I stated above with the polystyrene film caps used through out that amp. The biggest problem is that fact that those caps are used in all four voltage regulators. Therefore, given the amps age, if the amp hasn't had power supply issues yet, it will. When one of the caps shorts, it takes out every single semiconductor device in that regulator which is extensive. If you or anyone is going to keep that amp and it does not have the new caps installed, have them installed. It's a lot less expensive to do it before the voltage regulators fail.

Hifigeek1, that would be a major problem. I hadn't read your post since it went up. I would suggest that anyone who owns the amp or is thinking about buying one check with c-j about it.

There is also a conrad-johnson owners site where you might be able to get information about this problem:
http://www.conradjohnsonowners.com/