Originally posted by Jerry
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There is not much difference in TGSL either, except that TGSL gain stages have a bias problem due to bipolar opamps use. LM358 in this particular configuration will pull output of the gain stage 10-20mV below gnd, while the minimum criterion for the comparators to trigger is +3mV (maximum sensitivity). With TGSLs biasing problem total sensitivity falls to ~2µVRMS vs 0.5µVRMS in IGSL. Hence, to gain over 10 db sensitivity in TGSL, you only have to go for FET input opamps with low input bias current instead of LM358, just like IGSL does. At maximum sensitivity you enjoy more of the silence, while I enjoy more of depth and some chatter, and it both happens with the same +3mV comparators threshold.
BTW, I put TL064 instead of LF347, and it goes a bit more into the + side.
You can try with TL062. Prepare for a bit of amazement.
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