Bass Practice amp schematic?

DanielWong · March 25, 2007, 02:02:16 PM

Does anyone know of an amp, similar to the Ruby's, btu voiced for bass? Can someone point me in the schematic for one, or tell me, how to voice a circuit for bass guitar?

Tubebass · March 25, 2007, 04:19:34 PM

I think you'll need more power than the Ruby can provide. Bass needs lots of power and efficient speakers to sound good with an acceptable amount of distortion. I just finished a battery-powered practice amp using a pair of LM380s in bridged configuration, into an old alnico-magnet 6x9" speaker. This amp makes a big bad three watts, and is probably almost loud enough to keep up with an unamplified acoustic guitar!

DanielWong · March 25, 2007, 04:21:18 PM

Could you possibly draw up the schematic/pcb layout for me? Where could I get small, yet decent bass speakers?

Tubebass · March 25, 2007, 04:41:13 PM

Well, the amp itself is just what's shown on the data sheet for the LM380. The two 380 chips, a trimpot, and a volume control...... that's it!
The speaker issue is a little harder, it's tough to find an efficient one. Car speakers, for example, need a ton of power. The one I'm using came out of a '60s vintage console stereo. Maybe something from an old boom box would work.

DanielWong · March 25, 2007, 04:56:44 PM

um, so you just modified the layout for the Ruby? like what?

Sorry, I'm new to circuit bending and "re-voicing" things

nordine · March 25, 2007, 05:05:39 PM

a TDA2003 based amplifier (10W max) is a good option

http://www.electronics123.com/s.nl/it.A/id.1742/.f

Tubebass · March 25, 2007, 06:05:03 PM

I didn't use a layout as such, just followed the schematic on the data sheet. It's pretty simple.

DanielWong · March 25, 2007, 06:50:41 PM

where's the data sheet?

Tubebass · March 25, 2007, 07:48:53 PM

Google is your friend.

www.national.com/ds/LM/LM380.pdf

Page 6, bridge amplifier.

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Bass Practice amp schematic?