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Making an Acoustic Phone Amplifier

Making an Acoustic Phone Amplifier


Mobile phones have revolutionized music listening
once again, but unless you’re wearing headphones they simply don’t have enough OOMPF to get
the party started. You can of course jack them into your stereo
system of choice, but there are definitely more elegant ways of pumping up the volume,
like with an acoustic amplifier. Don’t let the term “acoustic amplifier” scare
you off, it’s literally just a funnel which will amplify the sound coming out of your
phone. No electronics required! In this video we’ll be making an amplifier
for the iPhone 6, but this could be easily modified to work with many other mobile phones. We’ll start with an old horn picked up at
a flea market, a sturdy piece of walnut and of course the phone. Cut the walnut down roughly to size and split
the final slab into two separate boards. If you only have access to thinner pieces
of wood you can of course use two individual pieces as well. Using one thick slab will make sure the split
will be less noticeable in the end. Don’t worry, it will all make sense soon. Sand out the rough saw marks using a disc
or belt sander. The surfaces should be perfectly flat once
you’re done. Prop up your top board at an angle in the
vice. This is purely for aesthetics, giving the
phone a bit of a lean back in the final amplifier. Using a ball ended endmill mill a groove the
same width as your phone, and down into the board, but importantly not through it! It’s only supposed to hold your phone in place
and a snug fit is even better. Since the iphone has its speaker at the bottom,
follow through with a smaller endmill and mill a slot all the way through the board
just where the speaker sits. We also need a bigger hole further back through
the board, which is easily drilled using a forstner bit. Double check that the speaker and the slot
you milled lines up well with the speaker on your phone. Place the top and bottom boards together again
and transfer the speaker slot and the hole you drilled onto the bottom board. Connect the slot and the hole to mark which
area you need to remove more material. You can use a multitude of tools for this,
like a chisel or a Dremel, I chose to mount an end mill on a drill press and manually
move it around until I had removed the desired material. The idea is to create a channel from the speaker
slot to the hole. You can also file a bit on the top board to
open up the area near the exit hole. I know there are a lot of audiophiles which
will have issues with the acoustic properties of this construction. If you require high quality amplification,
this is not the route to take anyway. Sand the surfaces completely smooth, making
sure there are no loose splinters or anything around the holes. Time to rejoin the boards again, and you really
don’t want to use more glue than required. To be fair, I used far too much glue than
was needed, and was worried that the squeezeout would clog up the channel between the holes. You of course need to use enough glue to join
the pieces well, and to make sure the glue joint in between the boards become as invisible
as possible in the final product. Remember though, you can never have enough
clamps! The following day Once the glue has dried you can test the amplifier
for the first time. Play something on your phone and put it into
the slot. If sound is coming out the hole you’re well
on your way. Don’t worry though, it won’t be amplified
by much yet, but we’re soon going to remedy that. Let’s continue to finish up the base. Sand down the top, the bottom and the sides
to their final dimensions. You’re likely going to be filling up the amplifier
with sawdust, but a quick burst of air should clear that right up! We can now turn our attention over to the
funnel. Remember that horn from the beginning of the
video? We’re starting by disassembling it the best
we can, and since it’s just soldered together some heat and a big screwdriver comes in very
handy. Since you’re going to heat up the funnel a
fair bit, use some heat resistant gloves as well so you can handle it without burning
yourself. Remember, safety third! On this horn we lucked out and had a solder
joint which could be easily swiveled around to form the S-curve shape we’re after. Make sure it’s aligned straight, and add a
little more solder to make sure the joint is solid. You can now also use some solder wick to remove
some of the remaining solder elsewhere on the funnel. Solder wick is super useful if you’re working
with electronics as well, as it makes removing parts from circuit boards very easy. Figure out where you want the funnel to exit
the base and mark it with a pen. The easiest way to cut it off is probably
with a small pipe cutter. It works by basically forcing a circular cutting
wheel into the pipe cutting it little by little with every turn you make. Take note how I’m actually cutting the horn
off about a centimeter below the mark I made. That’s because I want it to sit slightly down
inside the hole in the base. Next we’re going to make a flange to hold
the horn to the wood. Start by forming a small sheet of thin brass
into a cylinder, it helps immensely if you have a piece of pipe the same diameter as
the horn to form it around. Place it in a vise and peen it with a hammer
to force the brass out, creating a small lip. Don’t smash it, just slowly and lightly work
it out. Once out of the vise you can fine tune it
with a pair of pliers. Place it over the pipe again and use the pipe
cutter to cut it down to length. Take a square piece of thicker brass and mark
out the center. Measure the diameter of the horn, together
with the small flange you just made, and drill a hole through the thicker brass to that diameter. Don’t drill the final diameter at once, but
work your way up with progressively larger drill bits instead. Since we don’t want a square flange we’re
going to have to round it off somehow. You could for sure use a belt sander for this,
but I really want to get it perfect, so the lathe seems like the right way to go. However, to minimize time in the lathe we
can remove some of the excess material using a hacksaw. Since it’s a bit difficult to start a hacksaw
on a angled surface, you can always file a tiny ledge for the hacksaw to grab on to. To hold the brass in the lathe we need to
form a mandrel to affix it to. Using some steel rod stock start by turning
down a small ledge with a step of the same diameter as the hole in your brass plate. Drill and tap a hole for a bolt to fit, which
will hold the brass in place. Now we can affix the brass plate to the mandrel. Using some double sided sticky tape also ensures
it won’t spin off while turning. Add a bolt and a washer to really keep it
in place. Using small incremental steps start to remove
material until it’s finally completely round. File the edges to remove any burs and remove
from the lathe. We also need a way to mount the flange to
the base, using a protractor you can easily mark out where you want your mounting holes
to be. Finally we can put our horn assembly together. Put the smaller flange through the brass plate,
and put the horn through the flange. Make sure you push it down to where you previously
marked. Place it into the base and make sure it sits
straight, and that your holes are situated where you want them to be. Break out the torch and solder again and solder
it all together. The idea is to heat up the brass enough for
it to melt the solder, you don’t want the torch to melt the solder otherwise it will
just bead up on the surface and not actually wick into the joint. You can see an example of just that just as
I begin to solder it together. Once cool we can clean the horn assembly up
a bit. It’s up to you how shiny you want it to be. I’m using a chrome polishing paste just to
knock the worst grime off the horn, but being careful not to take it all off as I still
want a patina on the horn that tells a bit of a story of its previous life. Make sure you clean off the polishing compound
with some soap and water. Scrub the joints well with a stiff brush to
also clean off the flux from the soldering wire. It’s a quite corrosive compound, and you can
already see how it has tarnished the brass around the joints. I’m deliberately not removing that tarnish
though, as I want the brass to also build up a new story and a new patina in my home. Now, there are a few things we still need
to finish up on the base. As the small flange we made protrudes slightly
under the thicker brass plate we need to remove a little wood around the exit hole so the
horn will mount flush to the base. Again, you can use a chisel or dremel here,
I just chose to use a big endmill as it was quicker and easier. And now it sits nice and flush with the wood. The front and the back of the base is still
unfinished, and I think we can make them a bit more interesting than just cutting them
at a right angle. The front will match the same angle as the
phone will lean in its slot, and the back will just have an arbitrary angle which I
think will look nice. Set your table saw to the right angles and
simply cut the front and back off. Using a piece of wood as a backer piece will
prevent any tearout which may occur from the table saw. Do you like sanding? Because we’re about to do a lot of it! Smooth out all the surfaces using progressively
finer grits of sand paper. I started with 80 grit and worked myself down
to 220. Make sure all the marks from the previous
grit are gone before moving on to the next. While you can sand in any directon, I find
it useful to sand diagonally against the last direction you sanded in, especially during
the coarser grits. Sanding with the grain in with the final grit
of sandpaper also helps to hide any tiny marks you may still have once you move on to the
varnish. Remember to break the corners as well, it
doesn’t have to be by much, but at least enough to catch the light. Also, varnish doesn’t stick well to a super
sharp 90 degree corner, so even a tiny bit of a roundover helps a lot. Finally it’s time to make the wood pop! Take a scrap piece of wood and double sided
sticky tape it to the bottom. This gives you something to hold on to while
varnishing. I’m using a satin polyurethane varnish which
I’ve thinned down a bit with mineral spirits to make it spread a bit more easily. The key here is many thin layers of varnish. Varnish the entire base, but be careful not
to get a lot of varnish down into the phone slot, as it may build up and your phone may
not fit in the end. I only did one coat of varnish in the slot,
to at least give the wood a little lustre. The first coat will probably not look great
once it’s dried. Still, take some 600 grit sand paper and sand
it down, not to remove the varnish, but to knock down any high spots from grain which
might have risen. Don’t worry if the surface looks dull afterwards,
the next coat of varnish will take care of that. Repeat this process 3-4 times for a nice and
rich coat. I generally don’t sand between the last two
coats, as that way I won’t end up with a dull spot in the varnish should I accidentally
miss a part. Now you may need to clean out the little recess
we made using a chisel before putting the funnel in place and marking the holes. Use a scribe or a centre punch and give the
holes a small divot to help guide the drill when predrilling for the screws. Putting a piece of tape on the drill helps
ensure you won’t go in too deep. It’s finally time to put it all together. Put the horn in the hole and screw it down
with some matching screws. To help keep the entire amplifier more stable
you can also put some rubber feet on the bottom so it won’t slide around so easily. Now all that’s left is just to sit down, pour
some of your favourite libation, que up something good and enjoy. How much does it actually amplify though? I don’t actually have a decibel meter, but
you can be the judge yourself. Thanks for watching! Why don’t you cue up one of the other videos
from Switch and Lever and pump it through your new amplifier? Also remember to follow switch and lever on
facebook and instagram. I have a surprise for when I reach 1000 followers
on instagram! Until next time!

100 thoughts on “Making an Acoustic Phone Amplifier”

  1. Sound vibrations travel better in wood than in air, so why would you remove material between the speaker and the horn hole rather than let the sound pass through the wood? alternatively, why wouldn't you make the whole thing hollow like some kind of acoustic chamber (like any acoustic string instrument for example)?

  2. Man this is amazing. Very good looking
    I know this is on a whole other level for safty

    But i know you could make that into chargerststion at the same time!

  3. Nice. Would have been nice to include the charger cable as well. If you want to measure the results use an audio measurement software like Smaart for example.

  4. A quick google search found a plethora of brass flanges that would likely fit, and could be sanded and polished to a mirror shine. Second, it wouldn't be very difficult to add a charging cable to that base and still keep the acoustic amplifier.

  5. Such a shame phones only last a few years and keep changing dimensions – I’d kind of want a piece like this to be immune to planned obsolescence.

  6. "If you don't want to use electricity from the grid, build an atomic reactor and paint it in a pleasant beige color."

  7. Its Cute and adorable!! just wish i had my own woodworking factory to make one HAHA!! anyway…i can raise the ante…..i see your horn and raise you one timpano!!! as a percussionist i just place my phone on one of my timpani drums and it massively resonates

  8. I actually have these machines, and I can appreciate what he's doing here, but I wouldn't go through all of this for a phone amplifier.

  9. To avoid getting glue in the channel, two identical groves could have been make around the channel and a rubber band placed in the groove during glue up.

  10. In short: don’t ever think to make one, just order it…your time is waaaaaay more valuable … unless you don’t have a job..pretty wife and lovely kids…then you better spent your life for this…🙏🏻😁

  11. One of the most wonderful examples of "over-engineering" I've ever seen. Thank you so much for this, it made my day! BTW, it looks wonderful and I wish I had the gear to make one!

  12. No big electric tools? who cares! what I learned here I can apply too so many other projects with simpler hand tools.

  13. Well, supposing that I have all those materials, tools and machines, at leas I have a phone with the speakers in the front, in the upper part so…
    I don't think that will work.

  14. you don't need all those tools, drill a hole put the horn in it and glue, they have those horns in craft stores, like Michaels and hobby lobby, channel in the side the block could have been wider… at home depot , etc they have a creaft area with standardized sanded thickness pirces

  15. I love the simple but straightforward directions. Wood – Check, Sander – Check, Drill – Check, Now where on earth is my metal lathe???

  16. afaik only water soluable flux is chemicly aggressive, rosin based ones can often just be left in place if the looks don't matter.. also they can't be removed with water, but need something like isopropyl alcohol to remove them

  17. Nice work! Now make one with a tuba and a tree stump. "For the yard".

    Challenge: No power tools. No adding wood. Stump + Tuba + Manual Hand Tools.
    Bonus points if you don't have to plug any holes.

  18. Gee notice how he is using music from about 1922 because this horn will have no low end but I bet it’s great in speech and it’s looks cool

  19. I have a 3D printer at home. I'm going to try and print a base. I need to find the horn first, but this is a really cool project.

  20. Nice job. Anyone with any ability to do crafts can easily build this! Kids you need to find a project and just do it! The learning how comes in the process. Some things are taught others are caught!😎

  21. Cool project. I am making one myself. I just wonder why it is "important" to not cut the phone slot all the way through the top piece? The phone would just rest on the bottom piece and wood could then be cut away around the phone's speaker location so the sound could go on through the wood to the forstner-bit-hole, then to the horn.

  22. And for those NORMAL people who do NOT have an uber expensive metal lathe laying around, either use some galvanized metal pipe atrachments, or if you just HAVE to have brass – buy a router collet & drill holes thru that. This video is really not feasible for even moderate level woodworkers. Lol

  23. MeToo, "Safety Third!!!" What a great way to remember the mantra! Master Switch & Lever, you well deserve the title of "Master." Like a musician we call "Maestro," I am in awe! And for you to play that archeo-audio is like a science fiction time traveler (Oh, wait, you are in this century, right?)
    Thank you so much for sharing your skills.

  24. I like the fact it would look totally at home in a Steampunk themed setting…

    And as far as people saying they don't have all the devices to make the project.. Improvise!!! I'm going to give it a go, but do it all by hand.. It'll take a bit longer, yeah, but it looks like a fun build..

  25. I love this! A few years back they sold these at a store called Restoration Hardware for around $150. and they worked great. Sadly Restoration stopped carrying them and most people do not have these tools at home to make their own.

  26. I Watched a movie from Korea, (GREAT movie) and the lead actress put her phone in a cup which amplified to music! A lot easier and cheaper plus,,,, It Works Amazingly! oh, the movie: "Something in the Rain". So cute I bought the video!

  27. Distroing horn?! For what? Yea, let's use oil paintings as a wrapping paper for i ph on. as well, Idiot!!!!!! Dumest Hindu I ever seen. No wonder why Alexander were beating shit out of you. Дегенерат!

  28. congratulations! Good job. From the tools you have and your excellent dexterity you can see that you are not a hobbyist. This is why it seems strange to me that you have not cleaned the welds on the brass better and once you have polished it you have not protected it with a transparent varnish. It would have been the best! Good day

  29. Nice project, but I had to laugh…looks like you have a machine shop you're working in, but you used a hacksaw to cut the brass base (not a bandsaw). The finished product is quite unique…for this day and age.

  30. Anybody else scratching their head these days… we spend decades perfecting stereo, improving recording technology, but now people are totally cool with listening on a shit 3” Bluetooth speaker, or something like this, in mono. And in this case, not even mono, but one channel of a stereo device. You’re going to be missing some things the artist and mixing engineer likely wanted you to hear. Seems like a pretty extreme case of poor form/function balance.

  31. I thought about doing something like this except instead of using a horn use a horn from an old Victrola record player. You can find just the horn at antique stores and just putting your phones speaker doubles the volume of your phone.

  32. Man! You're a crack! 😃😅
    Many "audiophiles" who likes the "Oh, so 'musical' vinyl" are gonna adore this impressive device.

  33. don't think i'd be able to make something like this for a long time to come but this is really nice looking

  34. Wow! Det där va ta mig tusan bland det snyggaste jag sett! 😀 / Looks fantastic! I would buy one on in a heartbeat 🙂

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