My newest speaker (/amp) project

[Shpoop]

Hey guys...it's been a while since I've been to this board (and I rarely come to the amps section anyways), so here's a quick refresher: recently I've gotten into cutting glass bottles and integrating them into speaker design.
See my most recent here:


Now my idea for a next project is a small desktop speaker system. But this time I want to integrate an amp, and I need your help. I want my amp to be able to fit into a standard "handle" sized bottle of alcohol.

At first I considered building an amp - I've got good circuit knowledge and am handy with a soldering iron. But whats preventing me from doing this is creating a heat sink, and purchasing/building/attaching the power supply. I looked through a couple DIYs and these were the parts that confused me. If you want to talk me through that, that's fine, but my main questions are the following:

Now I'm looking to purchase a small amp. It doesn't have to be powerful, as I will be using a single, small fullrange in each speaker. It does have to be small enough to fit in a "handle" though, or at least be able to taken out of its case and rearranged so that it can fit in a "handle". Do you think this is feasible? If so, can you recommend some amps?

Furthermore, I will be cutting the bottle open, putting in the amp, and then gluing it shut again. It is likely that the top opening will also be sealed shut. I imagine this could create potential problems for heating and ventilation. Are there any amps that are cool enough (especially since these will be relatively low power) that this will not really be a problem? And if it will definitely be a problem no matter the power of the amp, can you think of any way to mitigate this problem?

Thanks guys,
Matt

[john blackburn]

Could you integrate the amp into the base of the wine rack?
Heat is sure to be an issue if you bottle up the amp.

[Shpoop]

No, it is for an entirely different project. Even an amp that produces 10-20 W per channel?

[kaos]

Do I understand you correctly, 10 to 20 watts in the neck of a wine bottle???!! I’m not sure that even class D will get you there. If you want less power though, there’s the NJM2073. It’s used in a lot of desk top speakers and dissipates very little heat, but you won’t get 10 watts out of it.

[Shpoop]

what about this guy:
http://www.partsexpress.com/pe/showd...number=300-958

I'm sure the quality is scoffable compared to what you guys build, but it can get 15W/channel and is only 6'' wide.


But yes, you did understand me correctly (well not the neck, the body, and not a wine bottle, a handle.)

[kaos]

I see what you mean now (I think). A class D might best serve this purpose, though an LM1875 might also work (+/- 18 V rails would give you around 15 watts power, and an idle of around 2.6 watts, based on National's "typical spec").

[Shpoop]

Oh i see our misunderstanding, it's because I'm using the word "handle". A "handle", at least where I live, is often used to described a bottle thats about 1.75L in volume. So this amp has to fit in a 1.75L bottle.

And I'm thrilled that youre giving me suggestions, but could you explain what terms like "rail" mean? When it comes to amplifiers, I really don't know much.

[BWRX]

Even low power amps can dissipate a fair amount of heat, but putting any amp into a sealed enclosure is not desirable without some means of cooling.

Having said that, I've made some small class d amps that do not require any heatsink that can do about 7Wrms into 8ohms. At that output power the chip will get a little hot though. If you're operating at lower output power the chip should be fine even in a sealed enclosure. If you're interested in a couple of them shoot me an email.

[Shpoop]

Thanks Brian...do you know what they put into 4 ohms? And is the output variable?

[BWRX]

They can do about 13Wrms into 4 ohm but will get very hot. You definitely wouldn't want to run them at full power into 4ohms in an enlcosed case. A few watts shouldn't be a problem though.

These are just amp modules, so you would need to make a power supply as well. If you want volume control (I think that's what you mean by variable output) you will need to have some sort of preamp that can do that.