PC speaker amp?

Posted by Bluesheart on July 27, 2011 at 5:17pm

I know that if you use powered computer speakers as a cbg amp it will be really quiet due to the low output of the piezo/pickup (quiet ain't what I'm goin' for!) But, I do not want to spend much if anything on a preamp and really do not know how to build one. I seem to have read about a hack that would make it work buy bypassing the input jack on the speaker amp (has some kind of resistor in the circuit?) and tapping into the amp directly.

Anyone know if this will work or is it just an urban legend?

Thanks in advance for the help!

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Replies

  • petey twofinger August 12, 2011 at 11:40am

    Tall Tales from the seedy world of the cbga underground . legends , half truths , rumors , and murmurs .

     

    i did that once , on this particular amp there was a chip with a heat sink (the actual amplifying chip) , one of the pins had a resistor going to ground . that turned out to be setting the input gain . you can also try bridging it , (i can explain if you like) i have done this before as well . one thing to keep in mind is this , i have read that if you only use one channel , its really bad for the chip , like it gets hot and fails . so if you could utilize both channels . good luck , lemme know how it goes .

     

    by the way , i did a tillman preamp , it was less than ten bucks , its like 5 or 6 componants , an mp102 (transistor), a cap and a few resistors . if you are scroungy , you could fairly easily find everything except that transistor , but , i hear ya .

  • j bone July 28, 2011 at 4:08pm

    hey bluesheart  - had the same thought awhile back - slammed all the guts from a set of jbl powered comp speakers into a little swisher sweet box - without any pre-testing- haha- didnt work -

     then saw this thread and it resparked my interest - also watched the video post above - 

     so, i have been messin around with a pair of powered pc speakers - you can bypass the transistor on the board and get a much louder output - at least on this one i have - looking at the board it was easy to see how to jump them - soldered on a 1/4 input at the points beyond the transistors - 

     

    i also scanned the posts in- it goes to 11 - some one said - paraphrasing now - "a small speaker will get you a small sound" - i replaced the 2 x 3 1/2  inch speaker with a 4 inch speaker from a found house speaker - gets a bigger sound -

    this works well for a little bit of sound with a decent mag pick up - reg humbucker sounds alright - bass pick on my cbg sounds alright - but not enough for a piezo - and its def. not LOUD - 

     

     

     

     

     

  • Saner Cigar Box Guitars .com July 27, 2011 at 5:54pm
    I was going to give this a try. Just waiting for some speakers to show up at the local thrift store. Good luck.

    https://www.youtube.com/watch?v=C3w8Y3uX3zo&feature=youtube_gdat...
This reply was deleted.