Portable amp for MP3

[rasco22862]

Hello there. I`m looking for a portable amp (9V) proyect. I was thinking maybe the Ruby Amp can do the job, but is this suitable for the MP3?

I also found this http://www.diystompboxes.com/smfforum/index.php?topic=61480.0 in the forum, but I want a little bit more volume.

Thanks!

[Renegadrian]

you may want to try the TDA2005 - just google it and get the spreadsheet- there's an amp circuit that's easy to build and should give you enough juice...

[chilecocula]

I've used a bridged ruby (~1W) with my ipod and it can get pretty loud with the right speakers

[rasco22862]

I've used a bridged ruby (~1W) with my ipod and it can get pretty loud with the right speakers

What do you mean with "bridged ruby"?

[Renegadrian]

I've used a bridged ruby (~1W) with my ipod and it can get pretty loud with the right speakers

So what about the left channel?! 

(sorry I am an idiot...)

[liddokun]

I used a single Ruby with an mp3 once. It was plenty loud...my sister only needed it to take with her to an anime convention. I sent both left and right channel into the single amp.

[cab42]

Mac made a portable amp for MP3 a while ago, using an LM386:

http://www.diystompboxes.com/smfforum/index.php?topic=61480.0.

He also made a stereo version, use the seach function to find this.

Regarding bridged LM386's, see an example in runoffgroove.com's Little Gem (and propably in most datasheets for the 386):

http://www.runoffgroove.com/littlegem.html

Regards

Carsten

[spudulike]

http://www.headwize.com/projects/cmoy2_prj.htm

[chilecocula]

A bridged amplifier is a configuration for creating a larger output voltage swing than that possible with one amplifier by inverting a second amplifier and connecting the load (such as a loudspeaker) between the two outputs (Wikipedia  ). The little Gem MKII is an example of this kind of arrangement http://runoffgroove.com/littlegem.html .  Of course the amp is mono and the left channel is ommited, but it sounds good anyway.

[chilecocula]

double post...

[mac]

The 386 is a good choice because it can be loud with efficient speakers and batteries last a long time.
386s can also be bridged.
The stereo version has a little more output, but you need a bigger box, etc.
I prefer mono.

I´m working on a better way of connecting the mp3 to the 386 to solve impedance issues and saturation.
Also experimenting with a BD139/140 to get 2w or so.

mac

[rasco22862]

OK. Last question: What specification should i look in a speaker for this "Ruby MP3 Amp"?

Thanks

[mac]

Both lm386 and bd139/140, and many other chips, can work with 4 and 8 ohm speakers. If you want to make a 2w amp pick one rated 4w or more. The better the speaker the more output, that is, connect a ruby amp to a chip speaker and then to a 12" celestion and you'll notice the difference.

mac