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Permalink Reply by Scott aka Farmer Ted on December 20, 2014 at 1:33am

The components needed to make your own 9v guitar amp are rather cheap. Here in Canada, we used to have Radio Shack, which had a wide assortment of parts for that purpose. Unfortunately, RS left Canada, and left us with a store called "The Source", which only caters to everyday electronics like iPhones, cameras, and stereo accessories.

I found all the parts needed on Ebay. Most of the suppliers are in the land of the Red Sun. But shipping is usually free, although it takes up to 3 weeks to get a parcel.

Here is a schematic for one version of amp I make regularly:

Parts shown are:

LM386-N1 Op Amp IC chip

8-pin IC socket

10K-B Volume potentiomenter

10uF electrolytic capacitor in either 16v or 25v

220uF electrolytic capacitor in same voltage

0.1uF ceramic disc capacitor

330 ohm 1/4 watt resistor

LED light

9 volt battery clip

Perforated circuit board

SPDT on/on toggle switch

This circuit with the LM386 IC is rated at 325mW (1/4 to 1/3 watt) and drives most any 8 ohm speaker load. You can use two 4 ohm speakers in series to create an 8 ohm load. Or two 16 ohm speakers in parallel to get the 8 ohm load.

I often add to this amp circuit a line-out switch & jack, so the amp can be connected to an external speaker cabinet. This amp will drive a 2x12 cab at bedroom volume levels, and sounds awesome.

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Permalink Reply by Scott aka Farmer Ted on December 20, 2014 at 1:36am

I just made one of these circuits yesterday and made another cigar box amplifier. The entire circuit board measured about 32mmx32mm.

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Permalink Reply by robert jones on December 20, 2014 at 2:27am

You might like the TDA2822m IC. The chips have a lower cut-off voltage than an LM386 so you get a bit more battery time.

I build modified Tube Cricket amps running at 9v using 1T4 mini tubes in place of the 12AU7 with the TDA2822m in the power amp block.

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Permalink Reply by Scott aka Farmer Ted on December 20, 2014 at 2:35am

Swapping the single 9v battery for six 1.5v AA batteries also extends the play time too.

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Permalink Reply by robert jones on December 20, 2014 at 4:03am

True.

But pull up the datasheet on the TDA2822m anyway.

It can be operated in stereo or BTL mode, has a wide range for resistance load, operates down to 1.8v, has good THD, produces more power and doesn't require many more external components than the LM386 when in BTL mode.

I dumb lucked into using the 2822m by scavenging one from a broken CD player and trying the basic BTL circuit from the datasheet. I was pleased.

Do you ever add a gain pot to the circuit you posted?

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Permalink Reply by Scott aka Farmer Ted on December 20, 2014 at 5:07am

Yes. The gain on the LM386 has an internal gain of 20, which is increased with the 10uF cap between pin 1 (+ end of cap) and pin 8 (- end of cap) for a gain of 200. Leaving pin 1 & 8 un-tapped results in a tone "as clean as it is able". In a few previous builds I have replaced the 10uF with a 1K potentiometer, for a variable gain, and works well.

One thing I like about this circuit, besides cost and simplicity, is the sound. When guitar is played with a light or medium "attack", it sounds reverb-ish, with a harder attack it has a nice growl.

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Permalink Reply by the anonymous pick on December 20, 2014 at 1:39am

"instructions"   for  it   ?  not  really  that  i  know   of  ....   but you  can   put any   9  volt  amp  in a  guit  pretty much  , 

i  have  done  many  . and  really  it's as  basic and  installing   pre wired  pots and  pups  .   drill  the  holes  to  match  the  pots    , speaker  etc  .  but ... each  board will  be different .

a  few  basic  hints  ill share  is  ..  keep  the speaker  as   far away  from the  pup as  you  can  to avoid  feedback issues  .

consider    inverting the  speaker   facing into    your    box and mounting  it    on the outside   blowing  in  ..  this   will make   the  body  act as a bass cabinet  .  (most  9volt amps sound  tinny   )  this  will add  some bass  .  

 you  can  even  take apart  a   mini  amp    and    re-fit  the  guts  into   the  guitar  .  rip  out  the " in "  jack  and  solder 2 wires  going to  your   guitar  out  jack . easy  peasy .     (you'll  even   have a pre made  drilling template   for the controls   .)

and  boom!  ,   bob's  your  gay  aunt  .    ;-)

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Permalink Reply by john mackay on December 20, 2014 at 1:46am

good idea I never thought of that.

cheap as chips @ £12

thanks mr pick!

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Permalink Reply by the anonymous pick on December 20, 2014 at 1:57am

yer  welcome  ;-)

you  don't  even have to rip  out the  jack  ..  just solder to    its   terminals  . 

and   by   "rip"  i  mean "gently    de-solder and remove  "  lol.

 or  leave  it    as  is and add  a mini  patch  cord as i  did  here  . 

then it   is a separate  unit  and  you  can  plug the  guitar into  itself  or   another amp .

but  you  can  still  run  both  the other way  too  ,  just  by  turning  your  onboard amp  on  or  off  ..   you  can  even run  both at the  same time that way too .. which  makes  for some feedback  boost    fun .  

  

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Permalink Reply by Scott aka Farmer Ted on December 20, 2014 at 1:51am

Really? I just thought Bob had an allergy to women

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Permalink Reply by the anonymous pick on December 20, 2014 at 2:08am

it's  gotta  be  true  ..  i  heard  it   on the internet  from a guy  that  knows  the    dude  , whose  daughter      looked  after   bobs   grandmothers   goldfish .   

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Permalink Reply by Daryl on December 20, 2014 at 1:42am

I have the same problem with Radio Shack here in Florida! Crap selection, there are several options on Amazon and Evil-Bay. Parts to pre soldered. Ive found some good solder-your-own stuff that will work your bifocals! They do work nice when done and the price is good.

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