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Permalink Reply by David L. on November 3, 2019 at 3:29am

I Have done it a few times before the Artec amp became available (using a kemo amp module and a smokey amp circuit - both based on a Lm386 IC). Also a Velleman 3W amp kit that gave a clean output (not sure what IC). 

Personally I found that by mounting the speakers at the back of the box rather than to the lid I didn't get an issue with feedback with magnetic pickups unless I used an on board preamp and boosted the signal too much. Generally a piezo rod or disc was much quieter and the discs would feedback at a low volume.  This resulted in the piezo volume through the amp not being much louder than with the amp switched off.

The volume I got with a magnetic pickup and any Lm386 IC circuit would give a nice meaty overdrive sound (as you would expect as the 9v circuit overdrives as you turn the volume up).  If you also add a preamp to the signal it gives a bit more volume.  This was still no match for a plugged in amp so I moved the speaker to the side of the box so that it points towards the player.  This is great to get an electric guitar sound when travelling or when you just want to noodle without getting the amp lead and amp out.

Designs with the speakers fixed at the back of the box pointing forwards.... 

.. and with the speaker in the side of the box (I found a flat humbucker surround plus a bit of wire mesh made a good speaker cover)....

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Permalink Reply by Dave Barrett on November 3, 2019 at 4:11am

Very similar to David L., I've done this with a home-made LM386 amp and a Kemo Amp module.  I also mounted the speakers on the base.  I've tried 2 different speakers (Both from Visaton - 2,5" and 3"), and both are overwhelmed, even with 1 W, so find yourself a good speaker.  I have found it difficult to find the perfect speaker - good output with tiny dimensions to fit in a CBG.  Only feedback issues I've had are from sustain on certain notes (especially G on the 12th fret), bit this is pretty cool.

I chose this combination 'cause I still can't play with a pick - I like my fingers on the strings for a duller sound, which means very low volume if playing acoustic, and I didn't want to cart an amp with me all the time.

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Permalink Reply by Dave Barrett on November 4, 2019 at 1:27am

Somehow the photos didn't upload on my last reply (operator error for sure), so here are the photos I wanted to add:

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Permalink Reply by B W on November 3, 2019 at 6:19am

Cheers guys, thats given me food for thought, reckon I'll give it a go.

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