Mini or micro amp projects? Headphone amp?

[ewilderink]

Hello,


I have been lurking for a hmmm... since the forum started not too long ago.  I have built many projects that were posted schematics from Aron's page.  I have made friends with a few people.  Now I am tearing apart amps and pining for an apprenticeship with my local electronics repair store.  Tube amps do not scare me and neither does solid state (ok unless you are talking about a modeling amp like a line 6 or a Roland).

Anyhow!  I am bored lately building stuff for other people and my rig is pretty much where it needs to be for now.  Now that I have Ebayed, repaired junk amps, scrimped and saved,...ahem and hit the visa...ahem.  I finally have all the amp I need.  What I really need is a good small amp.

Here are my criteria for what I want to accomplish:

1.  Small, therefore small power supply (like 9v)
2. As many watts as possible.  I'd like to go 20, but yeah, I know.  I am guessing 5 watts might be my max limit.
3. It must be loud and clean up to 10 (I know I am being unreasonable here, but I wanted to present a challenge)
4.  It pushes a small speaker like a 3 or 4 incher really hard.  It will push a 12, but is happiest with a 5 incher or like a auto door speaker (I think 6  inches?).

Are there any projects here there or anywhere one could recommend?

I am about to resort to carrying around powered walkman speakers.  I do not want to buy a product (unless there is a superb one) when I can dream this up myself.  My zinky in frount of computer speakers was my best idea yet, but unfortunatley, it sucked.

Thanks all,
enrico

[PB Wilson]

I doubt you are going to get anywhere near 20 or even 5 watts with a 9volt battery, but if you want a cool headphone amp that can push a speaker and do it relatively cleanly, check out http://www.runoffgroove.com and look up the Ruby amp project. Mine pushes my 2X10 cab well and it is plenty loud enough to make my wife tell me to turn down (which isn't too hard to do).

It is not perfectly clean when pushed to 10, but gets a nice overdrive that is very musical and not anywhere near heavy metal distortion. The RunoffGroove guys have included several mods (I did the Bassman mod) and even have posted the Ruby with a Fetzer Valve project in their FAQs. Check it out and with only a few parts, you too can have a cool mini-amp that kicks the Smokey's butt.