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So I'm definitely a newcomer in the audio electronics realm but I've been really digging into circuits and experimenting with sounds. I've been focusing alot of time working through examples that use pairs of LM386N ICs for a distorted audio signal. In the circuit I've posted here I'm getting a loud squeal whenever I powerup the second LM386 in the chain. Could someone tell me what I have wrong that's causing this to happen and what I need to do to fix it? Thank you!

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    \$\begingroup\$ Insert 1 ohm and 1000uF capacitor, in TWO places, in the VDD pin of each IC. The oscillation likely has the VDD rail as feedback path. So filter that VDD. Perhaps increase the resistor to 3.3 ohm or 10 ohm. \$\endgroup\$
    – analogsystemsrf
    Commented Jun 10, 2019 at 14:37
  • \$\begingroup\$ @SunnyskyguyEE75 thanks for the comment, what would you recommend for improving the FET bias? \$\endgroup\$
    – greyBow
    Commented Jun 10, 2019 at 21:02
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    \$\begingroup\$ You have Vgs at 9V/2 which is in cutoff mode. Reduce Vgs so the drain Vd is well above 0V in linear range by moving R1 ground end to drain for self bias. \$\endgroup\$
    – D.A.S.
    Commented Jun 10, 2019 at 21:29
  • \$\begingroup\$ D2 is redundant. C2 cuts off low frequency \$\endgroup\$
    – D.A.S.
    Commented Jun 10, 2019 at 21:31
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    \$\begingroup\$ I don’t see a short path on Q1-D to V+ with a decoupling cap. And orange V+ leads from cap to IC is too long, delete diode and use the rails with cap close to both IC’s use twist pair with ground for in and out. \$\endgroup\$
    – D.A.S.
    Commented Jun 11, 2019 at 14:08

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I don't know if anything else is wrong, but always bypass your power pins. And I mean always, on everything. In this case it means a 100nF cap between pins 6 and 4 of each chip, placed as close to the chip and with the shortest leads that are practical.

You should also have some bulk bypass -- I'd go with a 100uF electrolytic cap from +V to ground, just about anywhere on the board.

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