Conrad Johnson Upgrades - A difference maker?

I also had my prem8a upgraded. Bbro is spot on as the improvements overall are excellent.

Another significant improvement is it is quietier

Well worth it IMO.

Well, Per Preference is some of this...

I'm a big CJ fan. 1st tube amp I bought was their MV45 with EL 34's. I LOVED that sweet, a bit colored "tubey" sound. I sold it and picked up a MV60SE and did not care for it's sound as much (although many say it's a way better amp). I Sold it and bought what I'm hoping to be my final amps, the 12's. Did this because I thought I'd get a bit of both the MV 45's and MV 60's characteristics but on a much higher level.

To date, I've been very happy with the stock build of the 12. And, BTW, I've mated these 12's with CJ's Premier 15 pre and feel it has been a very good combination.

Thanks for sharing all of you - I do have more knowledge from which I can base a future decision off of. I'll contemplate the matter.

Randy

Randy , I have not tried the upgrade myself., From what I heard , you would lose some of that CJ house sound that you are use to hearing.
If you plan on having both amps serviced , you might want to have your capacitors replaced , but with the original type and value.

You would not lose any of your smoothness , but your amps would sound like they did when you first bought them.

The upgrade may make sense for you. The 12's, in their stock form, are very laid back. Much more so than a 60SE, or even a 55. An 11a is probably the closest in sound. Doing the caps may quicken the sound a bit, but I don't think thats such a bad thing given how they sound stock. I don't see you getting the amps back and they sound like a 60. Maybe like they used to but with a little more life to them.

Another reason that you might want to send the other amp in to CJ is to make sure they are identical. If it was my amp, I would have them "repair" the other amp so both amps have exactly the same parts in them, as well as the same age.

Anyway, its something to think about (or keep you up at night worrying.).

Randy,

Having the C1 Capacitor upgrade will make a significant difference in how well your Premier 12 amplifiers perform. I had the upgrade done to my Premier 140 and the change was not subtle. The 140 was introduced 10 years after the Premier 12 and did not have a "tubey" sound to begin with.

I also own the Premier 11A which is in many ways a stereo version of the 12 monblocks so I am familiar, to a degree, with your amps. After the modification, the 140 was more dynamic, detailed, with better extension at the frequency extremes. Soundstaging, another 140 hallmark, also improved. It is no slouch unmodified but the upgrade was an all around improvement to areas where I thought the 140 was already strong, especially in comparison to the 11A. The 11A is a "sweeter" sounding amp and extremely musical as I imagine your Premier 12 amps are.

You will, almost certainly, lose some of that sweetness should you do the capacitor change. However, in my opinion, the benefits will far outweigh that loss.

Just my 2¢ naturally.