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Permalink Reply by John W on February 15, 2014 at 5:19am

Put down the soldering iron for a minute, those are mighty fine components and probably a big pain in the ass to deal with.

Just put the volume and tone controls before the LM386. Then adjust the pot on the board to find a tone you like. Probably it's best if you just open it up all the way, but you can experiment.

See the schematic I made. Pot #1 is your tone control - this should be 250-500k, and 500k is probably better actually. If all you have on hand is a 100k, wire it up and give it a shot and see if you like it. Pot two is volume. The tone cap is at #3.

You should be able to wire this up without solder to make sure you have the pots wired the right way around and to make sure it works. Once you like it, it should be pretty easy to solder the jack, the pots and the cap in place.

I'd send you links to what you need on CBGitty but it's down at the moment, for me anyway. Anyway, give that a shot and let us know if you have any questions!

Attachments:

• LM386.jpg, 42 KB

Permalink Reply by Scott W on February 15, 2014 at 6:42am

Thanks, John. Could you clarify for this newb: where is the input jack and where is the output to the amp module? I appreciate your patience with my near total lack know-how!

Permalink Reply by John W on February 16, 2014 at 6:40pm

I'm sorry I could have drawn that clearer. My handwriting isn't the greatest, but it says "Guitar" near the line on the very left of the schematic. That's where the input comes in from the guitar.

The middle terminal of the volume pot (the "wiper" of the pot) is what you connect to the LM386 module.

Make sure that the ground of the input jack and the ground of the LM386 module and the ground end of the capacitor and the ground end of the volume pot and the - terminal of your 9 volt all come together at the same place. Preferably you want them all to meet at one location. This is called a star ground, and it ensures that all of the places that are at "ground" are really at zero volts!

Sometimes LM386 circuits can be fussy about their grounds. If you get a lot of hum, check your grounds to make sure you don't have any accidental ground loops. Also check your power supply, if you are using a wall mounted supply, try with a battery instead and see if the ground problem goes away. Cheap wall mounted power supplies can cause a lot of problems, and depending on how the LM386 circuit is designed, it may be very sensitive to crud coming in from a cheap power supply. (Or it may be fine, who knows.)

Let us know how it goes!

Permalink Reply by Scott W on February 17, 2014 at 4:25am

I'm going to order the parts and give this a try! I really appreciate your time and sharing of info. I will check out the pots at CBGitty. I don't recall seeing caps in their store, but I will look for them. Does it matter if I use linear or log pots for either in your schematic?
Thanks again!

Permalink Reply by Bernie Mango on February 26, 2014 at 12:30pm

Hi Scott!!!!!

I highly recommend staying away from those pre-fabbed kits.  The best thing to do is just LEARN.

The LM386 is a nice little IC, and soooo many circuits can be made with it.  One mistake many new folks make is that they try to just jump right in.  Grab a breadboard to experiment with.  Even those of us experienced "tinkerers" always use them to prototype circuits before committing them to circuit boards.

Another thing to do is make sure to look at the datasheet for the IC.  It gives you all of the pinouts and circuit examples.

Those pre-fabbed kits leave no room for experimenting.  If you build your own, you have the freedom to design your own circuit.

There are also plenty of great existing 386 mini-amp circuits.  Look for: Little Gem, Ruby and Noisy Cricket for starters.

Hope that helps.

Don't hesitate to drop me a line for any help, too.  I've been building pedals and mini-amps for years.

Permalink Reply by Henry S on March 24, 2015 at 4:36pm

Hi Scott - I totally agree with Bernie in that the LM386 is a great chip to begin learning on --- I would also say to look at the Noisy Cricket as one to try. It was created by a guy who goes by Beavis and he runs a great site with a tone of supporting info. Audio pots are always best to use log pots also called audio taper. Linear pots are mostly used for gain control.