Conrad Johnson Premier 140 6922 tube swapping
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/ |
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. |
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. |
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. |
You're on the right track in just replacing the noisy 6922 at this point before doing anything else. As Tomcy6 and Xti16 have said, you need a starting point before you do anything else. I own the Premier 140 and it's an excellent amp, one of the best that c-j made IMHO. I've also had the C1 Teflon capacitor upgrade done and was very pleased with the result. At $2,300 it wasn't cheap but c-j will bring the amp up to spec while they're doing the upgrade. Although I know it can be tempting to just jump in, start at the beginning: get another input tube (I've used 6DJ8, 6922, 7308, 6H23, and even 7DJ8 all without issues and all sound different depending on the brand and vintage), get the background info from the seller if you can on hours in service, and then go from there. There are current production tubes (both input and output) which sound excellent in the Premier 140 that are a lot cheaper than vintage types. Some NOS tubes can be very expensive but if you're patient you can find almost NOS (ANOS) that won't break the bank. Some NOS input tubes can be more realistically sought since you'll only need one for the input tube versus 8 for the output tubes. Drop me a line if yyou want to discuss any of this in more detail. Good luck with the amp, you're going to really like it. |
01-10-13: Agathe79Do you have a clue what NOS 6550's go for if you can find them? Then which ones are you looking for? Solid Black Plates (best and my favorite) - Solid Gray Plates (close second to the black plates) or the 3 hole gray plate? I haven't heard the 3 hole ones but a friend has them and says they are not as good as even the solid gray plates but still very good. Here is a link to e-pray and if the quad of black plates is truly NOS that is an excellent price. http://www.ebay.com/itm/Tung-Sol-6550-KT88-Black-Plate-Tubes-NOS-Perfect-Matching-Quad-/160951867413?pt=Vintage_Electronics_R2&hash=item25797a9815 Finding USED singles and pairs and an occasional quad isn't that hard. But most important you need to hear them first. In my Octave they are like great EL34's on steroids. Warm and musical. EAT KT88's are the opposite sound. Very detailed - linear and accurate (kind of like solid state). The Vintage Gec KT88's are pretty close to the EAT KT88. Depends on your preference and again why you should listen to them first - if possible. Only the EAT's are currently in production - all the rest will never be made again. All are very expensive and because EAT is currently in production they are the only ones that will give a warranty. That being said I'll also say get used to what you have first. Then decide if you want to change up the sound a bit which way do you want to go. Changing the input tube will make a big difference too and cost a lot less to experiment. |
Agathe79, This is starting to spin out of control. Your original problem was a noisy 6922. If you are happy with the sound of your amp except for the noise, get a new 6922 and see if that takes care of your problems. If you can talk to the person you bought the amp from, find out how many hours the power tubes have on them. They may have plenty of hours left on them and you can take your time getting familiar with your amp and opinions on tubes before you start replacing them. Also find out if the amp was left on all the time and how many hours it has on it. When you have that information call or email c-j customer service and find out what they think about replacing any parts before you do something like that. c-j will be glad to help you even though you didn't buy the amp new. You can also find out if there is someone who works on c-j gear with a good reputation near you. They could check out the amp without having to send it off to c-j. Take it one step at a time. Get a new 6922. Talk to the former owner then c-j. Take some time to get familiar with the sound of your amp. Your amp may be working just fine and not need anything other than a 6922. |
OP I assume your unit is stock. Given its vintage I think money is much better spent on checking out the caps and resistors and tubes in the gain and driver stage before you risk any $ going into the hands of the too many scammers selling those so called NOS power tubes out there. Bad power tubes do not contribute to noise. They just sound dull and wimpy and eventually wont bias and may pop. Noise is from components in the gain stage. |
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. |
c-j will tell you to only use replacement tubes from them, but I have not heard of anyone having problems because they used tubes from other sources. The 6922 is a member of the 6DJ8 family of tubes along with the 7308. Many people consider the tubes in this family to be interchangeable but you probably should stick with a 6922 (E88CC in European designation) until you become a little more knowledgeable about tubes and your amp. If you want to buy current production tubes like the EAT google Jim McShane and give him a call. Many people sing his praises here on Audiogon. He is away until next Friday though (I just checked his website). If you want to experiment with vintage tubes, I can recommend Upscale Audio, Andy at Vintage Tube Services, Tubemonger or Brent Jessee. Be prepared to tell them what kind of sound you want from your amp and they can fix you up with the right tubes, probably - no guarantee exactly how a given tube will sound in your system. The prices that these dealers will charge are quite a bit higher than what you can find on Ebay but believe me, in the end it will be cheaper to buy from them. |
