Gramazon - The Acoustic Echo Amplifier!

by IamStarGoat, published

Gramazon - The Acoustic Echo Amplifier! by IamStarGoat Mar 8, 2018


I have always loved the look of the old radio horns of the 20’s and 30’s, but sadly, acquiring them is becoming harder and harder these days, and when you do come across one, the price is usually very high. There are reproductions on the market in the form of standalone bluetooth speakers, but these are usually sold at an even higher price point than the originals.
I had almost given up on the idea of getting one of these until I had the aha-moment so many of us makers have at some point. I realized “Hey, I have a 3d printer, so why not just make one?” and so off I went to Fusion 360 to see what I could slap together.
Initially I was just going to make the horn part, and make a wooden base for it to house some electronics for a Bluetooth receiver and speaker, however, looking at my Echo Dot sitting at the corner of my desk, a light-bulb went off and the idea for the Gamazon was born!

The design is pretty straight forward, and is designed with the mindset of not needing to go out and buy any parts other than some paint, witch is of course completely optional. Just print, assemble and enjoy.

Print Settings


Monoprice Maker Select V2






0.1 mm and 0.2 mm




Parts to print

All parts except for the base and lid (which was printed at 0.1mm) was printed at 0.2mm using PLA on my modded Monoprice Maker Select V2 with a 20% infill.

These parts make up the neck of the horn and will need to be glued together. I have also included the whole neck as a single file if you would like to chop it up yourself.
  • Neck_01.stl
  • Neck_02.stl
  • Neck_03.stl
  • Neck_04.stl
  • Neck_complete.stl
This is the mouth of the horn and should print fine as one piece.
  • Horn.stl
This is the ring connecting the neck to the mouth. Supports are recommended for this part.
  • Joint.stl
This is the lid of the base which connects the neck to the base.
  • Bottom_chamber_lid.stl
This is the base of the speaker, and doubles as the acoustic chamber channeling the sound from the speakers of the Echo to the horn.
  • Bottom_chamber notch.stl
This part is completely optional and is for sealing the hole where you slide the power cord through by slipping it onto the wire. In my testing I have not found using this part to have any benefits to the sound, but it does provide a cleaner look to the base.
  • Holeplug.stl


Assembly Instructions

Start by gluing the neck together using the pre-split pieces or, if you can figure out a way to print it, use the complete neck model provided.
Next, assemble the whole horn using the joint.stl file to hold the neck and horn together. It is recomended to use glue for this step as well, but not necessary as it should be a fairly tight fit.

Now that you have the horn assembled, you can either glue it to the lid or friction fit it.
I recommend just using friction to fit this part so that you won't have to print and repeat all previous steps if there is ever a major design overhaul to this project.

Push the power cord through the hole at the back of the base, and while the lid is still off the base, drop the Echo Dot into the lid from the top and connect the power cord to it.

NOTE: It is important that you do not glue the lid to the base/acoustic chamber, as doing so will make it impossible to mount the echo dot to the lid. (I learnt this the hard way!)

Since the horn itself is fairly well balanced, and the echo adds extra weight to the lid, I have found that it shouldn't be necessary to do anything else to attach the lid other than a friction fit. I suppose some magnets could be added but as long as you don't roundhouse kick this thing its not coming off by itself.

Now just place the lid with the Echo Dot in it on the base and you're done!
You can now put the lid on and tell alexa to play your favorite song!

My Finishing process

After printing I rough-sanded all surfaces using 80 and 00 grit sandpaper, and applied copious amounts of Bondo to them. The rough-sanding helps knock down the highest points. as well as helps the Bondo adhere to the surfaces.
After the Bondo had have time to set up properly, it was nothing but sanding, elbow grease, primer and more sanding.

The primers I used was Rustoleum's high build filler primer, and their run of the mill gray primer.

Since the inside of the neck would be difficult to sand smooth due to the angles and lack of working space, I used XTC3D for smoothing out this part.

All in all, each part was given at least 1 coat of Bondo, spot putty and 3-4 coats of primer with wet sanding between each coat. Just expect a lot of sanding if you plan to achieve a smooth surface finish on this project.

Bondo bondo and more bondo

The paints used was Rustoleum's ultra cover flat black and metallic copper. Both rattle cans.


How I Designed This

I modeled everything using Autodesk Fusion 360. I started by laying out sketches for all diameters of the horn. The first part I made was the widest part of the horn, simply called Horn.stl here on thingiverse. This was made using 3 sketches driving a loft. I then used the Shell function to hollow it out.

The neck was made in pretty much the same way, however the amount of sketches and angles to drive that loft function took some tinkering to get right. I am in no way an export in the use of Fusion 360, so after much trial and error I finally had a shape I was happy with.

The sketches driving the loft function for the neck.

The base was a similar story; More sketches and measurements.
It helps having a pair of calipers in front of you to help visualize certain dimensions while designing. Figuring out how much you want a part to stuck out, or how thick you want something, is much easier this way. And of course it's a must if you are designing something around a pre-existing object, in this case the Echo.

Some of the sketches that went into making the base.

Since the Echo have its speakers on the bottom, it lends itself very nicely to a project such as this. In fact, most pre-existing amplifiers for the echo Dot simply lift the Echo off the ground, so I decided to build further on this concept and made the chamber inside the base mimic this principle, in the simplest way possible.
Since I wanted to make this project with as little supports needed while printing as possible, I decided to just add a fillet to the bottom edges, and let the lid serve as the roof for the acoustic chamber. If I'm ever to do an update to this project, the chamber design is probably what I will work on, but so far, it works quite well as is!

An "x-ray" of how the Echo Dot sits in the chamber, exposing its speakers.

I hope you find this project as fun to make as I had designing, printing and painting it.
Its been in the works for some time now as a "nights and weekends" kind of project, and if you do make one, be sure to post your makes! I would love to see them!

Over and out!

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Hey there
Great design, is it possible for you to make connection rings or joints for the other 3 parts. Printing this with pla and the gluing is a challenge but with the joint it makes it easier. :)

Hello! Check out this remix of this project, where someone already added the rings in question: https://www.thingiverse.com/thing:2845710

Gramazon Remix (with connector rings)
Comments deleted.

здравствуйте. какую электронику вы используете?

Здравствуйте! Электроника - это Amazon Echo Dot V2.
Я не говорю по-русски, поэтому надеюсь, что этот перевод Google верен, ха-ха.

Any plans for a base to fit the echo spot? This would be awesome for my nightstand

I'm sure it could be done, but I currently have no plans to purchase an echo spot for development purposes only.

One of the most inspiring 3D prints on here!

I like you have been looking for old Gramophone horns, nearly 10 years now, and the prices just keep rising.

Will be printing this in near future.

Many thanks for your time in designing and putting up on here, just have to buy an echo dot now, but for this it will be worth it.

This is amazing. its sounds old school like its being played off an actual record.

OMG... Soooo much sanding.... I am in the paint stage today (finally!!!!), so I don't have much more sanding to do other than fixing my sagging paint on the inside of the big horn because I was painting with crappy light and didn't see how much I was actually laying down. lol
You've set a high bar with your post processing work, so I wanted to try at achieve that level of quality. I got close, but I am done with sanding. I am officially sanded out... haha Can't wait to do these last bits and I will do my Make.

This is one I would do in abs so you can use acetone to finish

Great and fun idea, beautifully executed. Thanks for the awesome write-up, and great finishing tips.

Question about the joint. Is there a real need for it? Or could I just glue the neck to the horn?

If you want you can just glue the two pieces together and call it a day. Its mostly there for decorative purposes as most of the old horns had it. The diameters should be the same on both the neck and the horn.

Just finished this and it's awesome! Thanks for designing it. To get the full effect ask alexa to play some 20's music when your done.

What do you suggest using for gluing the neck pieces together? Second, because of the glass build plate and the location of the sled screws in my Maker Select V2, I only have about 180x180mm build platform. I sized the horn down to 80%, but left the base and lid at 100%. Any idea on how to best fit the neck into the lid?

I usually use plain old superglue. The one I use is made by BSI and is the fast setting purple one.
If the neck is printed smaller but the base is regular, then you could make a coupler to go between them. If you don't want to print or design one, wrapping some electrical tape or simular around the bottom end of the horn until it fits tightly is an option.

Soooooo cool!
The base is printing as I type this, almost 19 hours so far since I might have gone overboard with the infill 80%:) and if that impact the sound to much I guess I'll redo it:)

Awesome! Yeah when I printed my base I went low and slow on the settings and ended up with a 36 hour print. :P

All done and i posted the make aswell :)

Took 22 hours for the base and now the end piece of the horn is printing and hopefully by tomorrow at least the entire horn will be printed i prefer to start with the big things since i always get more impatient the fewer pieces are left of a big print :)

This is amazing, sent you a tip!

Yay! Thank you so much! :D

Awesome work... this so deserves to be "Featured".

Thanks for sharing this and making detailed instructions :)! I can't wait to print it. I found it here:


Thanks! Looking forward to seeing your make of it!

Wow!!!! Love this....Very Nice Work!

Saw this on Reddit, Can't wait to print a couple. Good job man!!

Thanks! Don't forget to share your makes! Cant wait to see it!

This is so awesome!
Can you make one to house Google Home Mini?

I would love to have this for my mini

First off: this is such a cool design!

I just have a quick question for you. Did you design it for the V1 or V2 version of the Dot? There's a slight size difference.

It was designed to fit the 2nd Generation.

Very pretty - But can you comment as to what extent this improves the eDot sound? I have most of mine blue-toothed into always-on Bose Minis, but still have a couple standalone's. They do sound terrible compared to the Bose. Any significant improvements with the horn?

I suppose improvement is a very subjective matter. For me this was above all an aesthetic upgrade, but It does amplify the to some degree, more than my old raised base amplifier that I was using before did, and it shapes the sound a little to a "warmer" sound. (if that makes sense) Its not as "tinny" as the dot is by itself, but if you're looking at it from an audiophiles standpoint, its not going to make the dots speaker sound crystal clear. Just louder. The audio used in the video here on thingiverse is recorded using a Røde VideoMicro positioned about 3 feet away from the speaker.

Any way to start a fund to commission a google home mini version of this? I got 10bux on it.

I don't currently own a google home mini, but looking at the tear-downs of them, and where the speaker is located, Im confident it wouldn't be a problem to design another base for the horn, to fit the speaker directly under the horn as the speaker is located at the top of the home mini.

That would be awesome!

That would be super great! Tipping you 5bux now, and another 5bux when you are done. Now I get to figure out how to tip people for designs...


*edit looks like you also need to setup some things so you can recieve tips. Let me know!