Rerurn to Romy the Cat's Site
In the Forum: Audio Discussions
In the Thread: Initial thoughts about new/old Lamm ML2s
Post Subject: Replacing V2 and the year of playing catch-upPosted by Paul S on: 1/5/2008
Lots has been written already about tube replacement, but I want to mention my recent experience when replacing the 6C33C output tubes (V2). I had the previous tubes in for only about 1 year; in this case I estimate about 300 hours, although I do not keep a log. FWIW, I got the previous tubes from Lamm because I could not find anyone else at that time who could/would match them for gain. Lamm now wants 192.00 USD for a pair, so I shopped harder. My new ones are from Ken Chait. We'll see what happens.
So, who knows how much additional "service life" the previous V2 tubes had/have on them? It's hard for me to believe that the V2s only last 300 hrs, although I might only be getting 100 hrs from the stupid 6N6Ps. Anyway, the bass started to go, it sounded like V2, and new output tubes got it back. I will continue to use the "old" output tubes as voltage regulators (V1), as Romy suggested, since it has worked fine so far.
But the main thing I wanted to pass on here is to remind other ML2 users to be careful about bias settings when installing new V2. My old tubes had just checked at 185V/28mA, and I was only reminded to check the new tubes when I could smell them. At that point they were 64mA! No harm done that I can tell, but I'm glad I stuck around rather than leaving the room while the amps "warm up" for 20 minutes, like I usually do!
Anyway, let this be a cautionary tale.
As for ongoing impressions and reflections, I am still a long way from wanting other amps. I get the "polite" criticism, but shoppers should keep this in perspective. It is certainly not what I am mainly conscious of when I listen, and there is so much upside for my application that I am still basically delighted with these things. Also, I am still a long way from realizing the best the ML2s have to offer when the AC is good, even with my present speakers. As it happens, the ML2s are also far less prone to suffer from bad electricity than my phono stage, so I can often enjoy CDs when LPs are out of the question, which is a nice thing, I think.
I wound up spending all last year trying specifically to take more and more advantage of the special things the ML2s do for my speakers, including not only new front end stuff but also new Audaphon ribbons and other tweaking of the speakers themselves. I reiterate that I was not at all prepared for these amps when I first heard them, and now that I am +/- "prepared" there is still lots to be done to tap them out.
Browsers, theorize all you want about the "negative effects" of feedback and/or SS power supplies; it is hard to imagine better "general purpose" amps for even nominally-compatible loads. I still would not use these for <92 dB, multi-way speakers, but I still think any normally psychotic audio nut job with semi-normal, nominally-HE speakers would be well served to give these a try. The only thing to lose is the rest of your system...
Best regards,
Paul SRerurn to Romy the Cat's Site