(http://runoffgroove.com/littlegem.png)
Thank you runoffgroove.com!
386 amps are a lot of fun. One change I would suggest would be to add a 10uF cap in series with the gain pot with the + side connecting to pin 8. That cap will preserve the DC balance on the input stage for sweeter distortion.
You can also rig a volume control using a 500 ohm pot. Just place it in series with the speaker. A 1K pot in parallel with a 470 ohm resistor will also do the trick.
For the sweetest distortion, the high voltage versions seem to give the best results. These would be the LM386-4 and the JRC386BD.
Here's the LM386 datasheet:
http://cache.national.com/ds/LM/LM386.pdf
Welcome Peter!
RDV
This looks like something I might want to build....would you place the speaker where the rhetostat is? Or is it connected some other way? Also, where could you buy a speaker for a small amp like this and is there any specific kind of speaker I should be looking for? Thanks.
Quote from: jedisteve on March 07, 2007, 02:10:01 PM
This looks like something I might want to build....would you place the speaker where the rhetostat is? Or is it connected some other way? Also, where could you buy a speaker for a small amp like this and is there any specific kind of speaker I should be looking for? Thanks.
Like all other guitaramps, this sounds best with a dedicated guitar speaker. These kind of speakers are built to sound good with guitar frequenciez, though I'we heard people have had success with car speakers and HiFi speakers with the Gem, too. I tried some 4" car speakers with my Ruby, wich is a very simmular design, and they sound like *s!!t*. Generaly, a guitar speaker should be at least 8" to be able to reproduce the guitar frequenzies correctly. Google jensen Mod speakers for some really cheap and really good guitar speakers.
The speaker connects with the positive wire to where the schematic says "OUT". The negative wire go to ground.
You'll find perf and PCB layouts at http://www.runoffgroove.com/littlegem.html
Just thought I'd tag onto the end of this old thread...
I haven't built the Little Gem but I've built the Ruby amp from RunOffGroove.com (which is based on the LIttle Gem).... Their website has sound clips of both the Little Gem and Little Gem MkII.
And I really dig the Ruby... I've used it powering an old 2x6" cabinet and my Kustom 2x12" cab, they both sound nice for the simplicity and price of the amp.
The Ruby does a pretty good clean sound as well, and the drive really isn't bad. I'm considering building a dedicated 9v amp with several switchable circuits built into it such as the Little Gem, MkII, Ruby, and maybe one or two others.