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jessie.dazzle wrote:

I should mention that with all the wonderful things it does, the L2 (preamp) definitely deserves a fresh pair of 12AX3s and a 6C19P. (I have not changed them since starting work on the horns... all tubes are exactly one year old, which with my listening habits is more like three years).

Jessie, the retubing of L2 is necessary but it will not affect the noise that preamp output. The MF nose that is coming from it is the noise of MOSFER output stage and it is intrinsic with the topology of the given preamp. Well, I do not know if is it really correct but it was what Lamm was truing to convince me when I complained about the L1/L2 noise.  Still with 109dB sensitively and ~25dB gains in ML2 you might mitigate the noise and make it practically auditable. You have too much gain in your playback for 109dB sensitively. So you burn ~8-12dB in the L2 attenuators, use it at the very first clicks. However, it is the L2’s out stage the one the produces the noise and the noise is constant with change of volume (I called it “bias noise” but it was juts my name). So, what you can do it to let the L2’s output stage to run full throttle (the L2 has unity gain when attenuator points at 1PM) but kill the gain at ML2, or AFTER the preamp. So, this way you will have your ~8-12dB voltage divider at ML2’s input that will kill voltage ALONG with the noise of output stage. It means your noise will be ~8-12dB less but you will add volume of music by more opening up the L2 attenuator (not to mention the L2 sound better when it more opened).  I used ML2 with 109dB sensitively and L2 with 12.5ddB voltage divider at ML2 and I had no annoying noise at nearfiled.

Also, a very few words slightly off the subject. If you did not replace the 12AX3s and particularly the 6C19P for a year then your preamp is absolutely dead sonically. A few years ago Lamm in response to my publics criticism of extremely low lifespan of L1/L2 power supply made a note on his site recommending to change the 12AX3 and 6C19P once a year (it is after 10 year of L1 production). I still disagree with what Lamm said. The 12AX3 in L2 must be changed after 6 months and 6C19P after a month or two maximum (I would say 200-400 Hours, no more). I have personally witnessed L2 preamp where the 6C19P was dieing after 20 hours, I am not kidding. Sure, it is still regulated voltage and tested any my tester with perfect transconductance and cathode emission but it begun to sound with compressed white-noise injected of any tone… truly disgusting... So, buy a box of the 6C19P (that’s God in Russia they cost pennies) and replaced them as I did it – each time when I paid my apartment rent….

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