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In the Forum: Audio Discussions
In the Thread: Initial thoughts about new/old Lamm ML2s
Post Subject: Voltage Divider in ML2 Input StagePosted by skushino on: 10/7/2013
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I finally added a -15 dB voltage divider to my ML2s last week to fix the noise problem from my L1 preamp - Why did I wait so long?!!
The result is absolute dead silence. Nothing. Nada. It is almost impossible to tell if the system is powered on, even with my ear at the bell of the horn. The total absence of any noise results in a black silent background behind the music. No more annoying noise / hiss distraction. There is a psycho-acoustic effect of less stress and more relaxation during playback. The focus is solely on the music. I really love it!
My attenuation was implemented a little differently than Jessie's, directly imbedded in the amp's input stage, after the input filter cap to ground, C101. I replaced R102 (40.2 KOhms) with:
R1 = 37.5 K
R2 = 8.06 K
...and tapped V101 between the series resistors.
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(Not certain the schematic will upload properly. It is .pdf format. Wasn't able to use the image loader after several tries.)
The input impedance increases from 41K to 46K, or > 10%. Not confident yet if the higher input impedance yields audible benefits, but I don't hear anything negative. Just silent blackness.
A big thank you to Romy and Jessie for sharing your experience. This is a MUST do mod for any high-efficiency system with a similar gain structure and upstream noise problem.
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