Battery Powered Guitar Amp help

[filholder]

Hi,

I am trying to build a guitar amp for a friend. He is a professional busker here in London and wants a decent quality preamp (maybe with FX), amp and loudspeaker unit all in one. The project is making me scratch my head quite a lot i have to say. The unit needs to be run off 1 or 2 SLA battery and needs to run as such for at least 4 hrs a day. For the power amp section I am thinking either a t-amp or a LM3875 but the preamp and fx are causing a lot of head scratching. I have found a decent preamp on ESP but it requires a -/+ 15v supply, if i tied together two SLA i guess i could get a -/+ 13.8v supply. If i did this could i also send separate dual parallel wiring from he batteries to power the power amp section?

The unit also needs a separate CD in and i was thinking about using a high efficiency full range driver as final output.

Any idea, links or help very much appreciated

Phil

[karma]

i get about 2 hours with 4 cells with one of my chipamps

[I_Forgot]

I would think you'd want to go class D to maximize battery life and minimize size/weight. TI makes a bunch of class D amp ICs and has demo boards available for not too much $.

I_F

[DigitalJunkie]

Well,seeing as it's battery powered..
I'd go with an efficient amp (Class-D) that has just enough power to do the job,and a nice efficient speaker to make the best use of the power from the amp.

No need to burn 20W of battery power,when you can do it with 10W,and play for twice as long!

[CarlosT]

How about a pedal-powered dynamo so that he can jam as long as he wants?

No...really...now the whole thing needs to work off a battery? What...is he a street vendor?

[CarlosT]

Does your pre-amp have any gain? Most preamp chips out there are rated for a MAXIMUM supply voltage of 18V or 15V...it doesn't necessarily mean that they wouldn't run on less like 13.8V. BTW...13.8V is very optimistic...that will surely go down as the show goes on especially during the Voodo Chile Hendrix solo

In my short excursions looking at pre-amp basic building block chips, I liked the SSM2141 and INA134 although I've seen entire pre-amps contained in one IC as well.

[filholder]

Hes a professional busker on the London underground. Make very good money at it too.

That why he wants something better than the usual crap that out there. The best thing he can buy is a Crate Limo, they cost about £300 and he has 2 constantly on rotation as one come back from the repair shop the next next goes in. Also the sound is quite shite, no idea what chip are in them , they quote 50 watt and 10% THD so probably more like 25 clean.

I was thinking with and efficient full range and something like an Amp 3 it might be loud enough and his battery life should be better

Just to make sure i can run of 2 batteries a set of wires in series for the +/- 12v for the preamp and a parallel set for the t-amp?

[filholder]

Thanks for hte help so far, at least i now that the Overture chip are a no go.

[filholder]

has anyone got any guitar preamp or fx cicuits i might have a look at?

[Minion]

If you are looking for Guitar effect circuits take a look here:

http://www.diystompboxes.com/smfforum/index.php


I have used a couple circuits found here and integrated them directly into my Guitar amp, The good thing about most of these circuits is that since they are for Pedals they will run off of a single Supply Voltage (+9v) and some will run even better at higher Voltages.....

I recently built a really simple Guitar Overdrive/Booster pedal that sounded great and integrated really easilly into my Guitar amp design.....If you are interested I can post the schematic and PCB for you....


Cheers