amp wiring help

So I bought a little 'amp" circuit on ebay based off of some comment I saw here on the nation metioning them.  It was only 3 bucks, so I figured what the heck.  anyway, it showed up, but no wiring diagram, and I don't want' to fry it.  It has some marks on it, perhaps someone has some knowledge on it.  the white circle with the slot turns....I think some sort of gain/vol.  then 4 prongs on right side say grd, grd, in and vcc.  then other side, i assume is speaker out, has green plastic bracket with screws that tighten down (I assume you clamp wires in there) and they are labeled grd and out.  My assumption is the "in" is the feed from jack, the vcc is the hot from battery, and then the grd are the respective grounds for them, which I assume all ground are interchangeable.  thanks for your thoughts!



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  • Fellas--that circuit is built around the LM386.

    It is capable of sooooo much more than these cheap boards do.

    Please consider building your own circuits.  It's easy and fun!!!  You can ad a pot between pins 1 and 8 to adjust the gain, and this little IC can put out a mean growl.  

    Also, the LM386-4 puts out 1w RMS.   Yes, you reads that correctly ONE WATT.

    Some great little amp circuits have been built around the 386--Little Gem, Ruby and Noisy Cricket...just to name a few.

    Do a quick look on YouTube for some clips.

    There are also so great OD circuits built around this chip--the Grace and Big Daddy are a few examples.

  • How does this amp module sound? ? ?  is it worth $2 bucks ? ? 


    these are what we have been using , the sure electronics amp boards . we have four amps including one for keyboards/theramin . the bass amp is 100 watts with 24 volts , two sealed lead acid batteries . it has a lil mixer hacked from a vivitar super 8 to video convertabox . we run a drum machine thru it as it has tweeters too . there is an ev 12 in one then a ten inch , both legit bass speakers in seperate cabs . we use multi effecters as preamp "front ends and then also to get stereo . my one kids amp uses a roland microcube as the front end , line out into the sure 2 x 25 , then into two 6 inch  jensen mods with external xam speaker extention cabs loaded with fenders out of lil champs  . i run 4 speakers with two tweeters off a 15 watt sure board and it is really loud but it has a stereo amz mossfet boost pushing it . i got two tens from an old organ , then a coupla fender 6's from champs , there are no shrortage of messed up champs floating around !

    you arent supposed to push these amps with a booster , but mine has held out , taken lots of abuse , never shut down  and we use them a lot outdoors in the summertime too . i couldnt be happier . they arent really mini amps OR full fledged amps , more like inbetween . but they are a lot louder than anything based on an lm386 and for the price ... i paid 22 dollars for the 100 watt board , it also has a nice heat sink and a cooling fan .

    as far as mini amps go , i am not so hot on lm386 so i purchased 15 tda7052a chips and i will be monkeying around with "punch " amp designs . the 7052 is dveloping the reputation as the lm386 killer in some parts and for good reasons . i am thinking of a fetzer valve on the input , then maybe a one knob fuzz or something , maybe a tone control but i would really like to keep it simple .

    i just used one of the above ebay lm386 modules recently to push  a spring reverb tank and it works well , although the board i got was a bit cheaper and really really tiny ! electronics goldmine has 4.8 volt nihm packs for 99 cents each right now . there is a ten dollar minimum , but i think two of those would work well as a rechargable power source for one of these mini amp designs . OR if you have a cordlless drill battery pack that has died , often times it is only one of those cells that failed . you COULD canibalize that unit , break up the individual c size nicad cells you find in there to power one of these units on the cheep . EG has 99 cent vactrols too ... AND lmc567cn ( ring mod chip) ... i spent like 20 .

    check out the amps in a clip below ... its an older clip and they have been upgraded with speakers since then but you can get the idea ...

  • Thanks foe all the helpful comments below. So I finally got time to wire this up , and I was pleased with the sound. Not the best sound ever, but considering it was $3 and only a half watt, very acceptable.
    • to improve the tone , especiall the clean tone , try running a pedal in front of it , if you have a pedal that contains a buffer circuit , often that will really help with lm386 amps . you do not even need to turn the pedal on , the buffer will be active in bypass mode . the way you could tell is this ... connect the pedal , have it bypassed , like no effect , just straight guitar tone , now dissconnect the battery . if you loose sound this means the pedal has a buffer and it should really improve the tone . if you want to take this a step further look into building a buffer for it . they really arent difficult to construct , they are cheap too .

      i have a tillman built ino my piezo cbg , it really helps . you can also use this unit to eliminate signal loss thru long cable runs and having too many true bypass pedals , etc ... they are handy lil guys to keep layin around imo. i have one here in a plastic box i use for monkey time and resist the urge to steal and install it , but build  a fresh one when needed . :)

    • Nice, if you have a pedal of some kind through it into the mix.

  • Hey Harley, I would say the 7$ one is a little louder, but having the option of a clean or gain amp is nice, or you could add a gain pot for adjustment. I run both at full volume & find for me I like lower ohm speakers for low watt applications as it adds to the DB level. I have 2 8" 4 ohms in parallel in a 20w buskin amp I built that also has the option as being a cab & the little boards drive them pretty good. I also built this little radio amp with the 7$ board into a 4" speaker & it sounds nasty!!


  • These are only about .5 of a watt, but they do crank for "watt" they are!!

    Here's another I tried, has external volume pot & a pin to go from clean to gain, not a bad unit. These are actually quite a bit larger then the one shown in this post. I had thought that a LM386 would only be one size, but apparently not.

    • I've got that module in an old bakelite speaker cabinet from the 1940's (the speaker cone is from the same era too) and it sounds really great. Far better than you would expect. I've bought a few more and am on the hunt for some more vintage speakers to hook them up to. I'll try and take some pics later and post them :)

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