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In the Forum: Audio Discussions
In the Thread: Lamm ML2.1 "No longer available"?
Post Subject: It completely makes sensePosted by Romy the Cat on: 3/21/2013
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 Paul S wrote:
He did note that the ML2.2 uses a different OPT, and also that it uses "less feedback" than the ML2.1 …  I wonder what this means, "less feedback"?  Why would Lamm mess with that very effective scheme?  Does he just shunt some voltage, or did he really change the circuit?  I see the 2.2 uses all the same tubes...

It completely makes sense that Lamm changed the amount of feedback. ML2 used if I am not mistaken around 12dB of global feedback that was injected back to the cathode of input stage. The ML2.2 reportedly uses the inputs stage from ML3. It is the same paralleled tube, perhaps with slightly different operational point and consequentially with different amount of feedback. I presume that sine Lamm did ML3 with more power he wanted to have input stage to be able to care more swing without going to clipping. So, he reset operation point of that 12AX7. I do not think that he modified anything topologically in input stage and it most likely the same tube with the same biasing schema.

The Cat

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