My newest speaker (/amp) project

This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
Hey'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,
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.
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.
Joined 2005
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.
Joined 2005
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.
yea, thats when we start getting out of my league. Thanks anyways :\

Also, this might be reallllllllllly stupid but...

For a cool visual effect, what do you guys think about putting the amp in the bottle, and then filling the bottle up with a clear liquid insulator. I could also imagine that helping with cooling. And remember the bottle will be totally sealed so I don't think we have to worry about things falling in.
Thats a great idea IMHO.

It will help ALOT with cooling, thats alot of thermal mass to heat up for such a small amp.

I would use mineral oil, like transformers do.

As for the amp, I like LM1875s, they sound great and as suggested before, would work well off 18V rails.
The physical item that relates to 18 volt rails is a 25 volt center tap transformer, like the incredibly inexpensive buyout model over at Parts Express. Its about $5

The item that relates to an LM1875 amp in easy condition is a K50 kit. Its about $12

To connect the two, the basic power supply of 4 diodes and 4 caps. This in a kit is about $12, available everyplace that has K50.

That'll make it all clear.

You'll need to find some glue that can conduct heat. You'll need to glue a metal sheet to the inside of the bottle--so that if the sheet gets hot then so does the Outside of the bottle.
Next, you'll need some way to thermally conduct the LM1875's heat onto that metal sheet.
I think that a "heat spreader" is called for. That would be connecting the LM1875 onto a 1 & 1/2" square bit of thick copper or thick aluminum. Attach the heat spreader onto the larger thin metal sheet.
OH!! OH!! The special glue to make heatsinks stay on video cards--thermal glue!!! That's different than thermal paste.
Try thermal glue.
Shpoop said:
thanks guys...the idea is starting to form itself in my head.

Daniel - does that mean you think the fluid idea is a stupid one? Or were you just replying to the first post.

I was just replying with something easy. However, there are clear substances that conduct heat--without conducting electricity or causing corrosion. The application is immersed in glue, and the term is "potted" to express a container full of glue, with the amplifier inside. When the rectifier and amplifier are both "potted" then this is known as "fully potted" to express that both are inside--the usual glue isn't clear.

I think your ideas are fantastic--thinking outside the box. ;)
diyAudio Editor
Joined 2001
Paid Member
First, the bottle speakers are just great IMHO. Would be interesting to try them with an open neck also- it would be a ported speaker then!!, but the port (neck length) would need to be calculated so you are probably better off with the cork.

Most chip amps such as those at have enough gain that you don't need a preamp. You just wire in a potentiometer (volume control) per the instruction manual.

As far as the amp in a bottle, potting compound isn't going to transmit enough heat to work well. Fluids? Well distilled water doesn't conduct electricity well, but after a short while it will have enough metal ions in it to conduct well I think, so I wouldn't try that. There is a liquid made for the purpose called Fluorinert I believe. It is used to cool super computer among other things. The problem is that I think that it costs about $300/gal.

So making a black box base that the rack sits on might work, or putting the amp in a decorative metal box next to the bottle rack. Even a wooden box such as a cigar humidor would work if it had heat sinks sticking out the back or an aluminum plate across the back with the chips mounted to it on the inside through openings cut in the wood .
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.