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In the Forum: Audio Discussions
In the Thread: Initial thoughts about new/old Lamm ML2s

Post Subject: 6c33c socket repairPosted by skushino on: 6/22/2010

Jessie-

There are the current japanese teflon sockets, and vintage american manufactured sockets - I think either should be fine. The pin springs on the OEM pair I replaced had no grip or spring characteristics. When the pin holders are bent, they stay bent and don't return. On the replacement sockets, the pin springs return to a tight-grip position. The replacements are clearly superior to the OEM parts.

'I too have fluctuating V2 plate current, forcing me to run the tubes at around 250mA in order to ensure that it doesn't creep above the recommended max of .31;'

I was operating my amp around 275mA for the same reason as you, to have a margin before V2 runs off the cliff. It happened to me once before. In addition to the fluctuating V2 readings, I was noticing audible 'noise' coming from the speakers when the probes were inserted and removed from the test points on the deck of the ML2. Since the test points are closely connected to the 6c33c sockets, the noise seemed to be consistent with trouble around the sockets. With the amp open, it was easy to see the sockets were already replaced at least once. The solder work was very sloppy and some of the wires were very loosely connected - these connections were clearly suspect. The exposed wire was brittle and dull. I simply cut the ends back until 'good' wire was exposed and then re-connected everything.

'One "advantage" of the cheap sockets used throughout Lamm gear is that they can be easily, purposely broken (carefully crushed with pliers), thereby facilitating their removal from the board; once broken, it is no longer necessary to simultaneously heat several soldered points.'

If I understand you correctly you are referring to crushing / breaking the old sockets for removal? I think it's easier to simply remove the wires and four screws, then removing the old socket is straightforward and simple, without having to destroy it and having to remove debris.

'While the amps are open, it would seem logical to replace all the sockets (those for the smaller tubes as well).'

The other (non-6c33c) tube sockets might be more 'interesting' to replace - at least it looked more difficult to me. These sockets are attached directly to the board, without direct access.

'I am hoping new tube sockets will solve this issue.'

Me too! Will post here if the problem doesn't go away.

Scott

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