Dual IM386 Chip amp

Posted by Paul Craig on November 5, 2015 at 4:51pm

A while back I posted on the comments about this nasty little op amp that I built. It has 2 IM386N1 chips and it's a 2 stage amp. It was inspired by the Ruby amp.

Here's a schematic if anyone is interested in building one.

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Replies

  • Scavanged Sound (Pete) January 26, 2017 at 7:10pm
    Hey Paul. Thanks again for posting these schematics. I whipped up the revised one and I have an issue maybe you can help with. I have sound coming through my speaker. The tone control works the switch for the cap values works and the 2nd gain circuit works. My ssue is with the first gain circuit. I am getting sound for it but also a lot of squelch. I know somethings wrong here. I've triple checked the wiring and I just can't seem to see what's wrong. I've switched out both chips 2 times and it still does it. Any insight into where I went wrong? Tips for trouble shooting?
    • Paul Craig > Scavanged Sound (Pete) January 27, 2017 at 2:22am

      Can you post a pic?

  • Scavanged Sound (Pete) January 18, 2017 at 10:27am

    Oh man.... you are the best....this is just what I have been looking for. I've been scouring the net for a schematic that had the pots included in the diagram. Thanks a million for posting this drawing.

    • Paul Craig > Scavanged Sound (Pete) January 18, 2017 at 5:58pm

      I revised the schematic and posted it at the top of the page.
      Changes are N3 chips instead of the N1's due to the N1 chip's not lasting long in a bridged amp.
      A change in pot/controls: 1 volume - 1 tone - 2 gain.
      Added caps in the output lines: the cap values will change depending on the speakers used.

    • Scavanged Sound (Pete) > Paul Craig January 18, 2017 at 11:16pm
      Thanks for the updated schematic Paul. What do you mean by cap changes due to the speaker?
    • Paul Craig > Scavanged Sound (Pete) January 19, 2017 at 1:37pm

      For example: The Ruby and other single chip amps have a 220uf cap in the + output line to the speaker. Since this is a bridged amp, it gets a cap in the + and - lines to the speaker.

      I used a WGS 8ohm 20watt 10" speaker for my build and I started off with the 220uf caps, but it was very very bright sounding. Might be what you like, just not what I was going for. So I tried a couple of different value caps til I got the tone I liked which ended up being 10uf for both lines. So the speaker you use(due to it's voicing) or your personal likes will determine which output caps will be best.

      My original build had no caps in the output lines, but also had a lot of unwanted noise and some oscillation.

    • Scavanged Sound (Pete) > Paul Craig January 19, 2017 at 3:09pm
      I did not know the about adjusting tone with the caps. Thanks for the info
  • Paul Craig March 30, 2016 at 3:01pm

    Here is the page from WGS on the speaker I'm going to use and the measurements are all listed at the bottom of the page. This speaker will handle over 93 decibels. Should be enough.https://wgs4.com/vet10

  • Paul Craig March 30, 2016 at 2:57pm

    A amps watt rating can be confusing at times because there's a operational wattage for the amp and a output wattage for the amp. Sometimes an amps label will show the operational wattage and people will think it's the output wattage by mistake. Example: My Silvertone 1482 tube amp says on the back label that it's a 117Volt 70Watt amp, but the output wattage is 15Watts.

  • Murdoc_420 March 29, 2016 at 9:52pm

     Would it be possible to get photos?

     I have done NO electronics work at all but scored a nice box today I can get two 6" speakers in.

    Would love to try it but photos would definitely help.

    This one looks good as I play bass and have a CBB I want it for.

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