My Overnight Sensation Speaker Build

When living in Berlin, back in 2016, I used to own a pair of M-Audio speaker monitors and I loved them, such an insane improvement from my computer or tv speakers.

Unfortunately, I didn’t manage to take them with when I moved to Lisbon in early 2018. After a few months in the new city, I decided that instead of buying a new set of monitor speakers, I was going to build one myself. Even have used a known design, there were many things that I had to custom build, and this is why I am writing this blog post, to share the process that took me from concept until the end. And I have to say, it turned out much better than expected 🤠!

The speaker

The Overnight Sensation speaker was designed by Paul Carmody to be an easy speaker build with amazing sound quality, and by his own words:

The “Overnight Sensations” were designed to be just that: a quick, economical build that could put out a surprisingly-big sound in a small box. Could be a weekender project for an addict, a gift for a teenager (see above), or–in my case–a set of small, full-bodied monitors that I could listen to while I graded papers. (Ironically, I have found that if the music sounds too good while I am trying to concentrate, I get distracted and get no work done.)

🤘 So let’s get started 🤘

Component list

• 2x Dayton Audio DNR-10 10 Ohm 10W Precision Audio Grade Resistor
• 2x Dayton Audio DNR-6.0 6 Ohm 10W Precision Audio Grade Resistor
• 2x Dayton Audio DMPC-0.22 0.22uF 250V Polypropylene Capacitor
• 2x Dayton Audio DMPC-1.5 1.5uF 250V Polypropylene Capacitor
• 2x Dayton Audio DMPC-2.2 2.2uF 250V Polypropylene Capacitor
• 2x Dayton Audio DMPC-6.8 6.8uF 250V Polypropylene Capacitor
• 2x Jantzen 1204 0.35mH 20 AWG Air Core Inductor
• 2x Jantzen 1078 1.1mH 18 AWG Air Core Inductor
• 2x Port Tube 1-3/8″ ID Adjustable
• 2x Dayton Audio ND20FA-6 3/4″ Neodymium Dome Tweeter
• 2x HiVi B4N 4″ Aluminum Midbass Round Frame

Note: You can currently buy the kit from parts-express, which would make things easier, but as I am living in Europe, I had to find other places to buy the parts. Most parts came from soundimports.eu and hificollective.co.uk. (PS: Stay away from loudspeakerfreaks as they are scammers).

Building the audio cabinet

For the cabinet, I decided to go with an 18mm pine-wood sheet, as it is sturdy and looks nice. In case you are going to completely paint the cabinet, you can also go with plywood, which is a bit cheaper.

To have a better understanding of the cabinet size, I based on the original designs and adapted to the 18mm sheet width and made a few modifications. The model was made using Autodesk’s Fusion 360, which you can download the 3D file here.

With all the sides carefully measured, I placed each side of the cabinet on a flat surface (the grey rectangle below represents the original full sheet) so that I could convert the files to be drilled using a CNC-machine.

Now it’s time to cut the wood, so I went to fablab lisboa to use their machinery.

After having each single piece cut and sanded, it’s time to put our new speaker together with some Wood Glue and a couple straps. I think the images are self-explanatory, but if you have any questions please let me know 😅!

Wow, it’s not looking too bad 🤩!!! Time for a bit more sanding, and it is ready to be painted (in case that’s your goal). For me, I wanted to create a speaker that looks a bit rustic, so what I decided to do is to paint it black, but not too dark, and then sand it again after to add an extra “used” look.

It’s time to move to electronics 👨‍🏭, my favorite part!

The crossover

In the crossover is where the magic happens, the circuit consists of two basic RLC filters, one high-pass filter that sends all high frequencies to the Dayton tweeter and a low-pass filter that sends the lower frequencies to the HiVi B4N speaker. If you want to know more about audio crossovers, you should check the audio crossover Wikipedia page for more information.

When I was about to put the crossover together, I realized I didn’t have a perfboard or didn’t want to design a PCB and have to wait weeks for it to arrive. The solution was to design a 3D board with the holes in place so that I could easily solder the components in an accessible way and that could be easily attached to the interior of the cabinet.

You can download the 3D file for the board from the thingiverse website. The last step if to put it all together, the electronics following the schematics from Paul, screwing the speaker and tweeter to the front of the cabinet and closing the box.

The amplifier

One thing you have to keep in mind is that we built a passive speaker, which means that we are still going to need a power amplifier to process the audio input signal and push it to the boxes. Initially, I got an SMSL SA-36A but quickly realized that the lack of a remote controller would be a huge pain in the 🍑 as I intended to use the speaker mainly on the TV, and have to keep standing to adjust the volume wouldn’t work. That’s why I changed the amplifier to an SMSL SA-50 and have been really happy ever since!

🥳 Celebrate and enjoy 🥳

“Ah, it’s time to relax.
You know what that means.
A glass of wine, your favorite easy chair,
And of course, this compact disc
Playing on your home stereo.
So, go on, and indulge yourself!
That’s right, kick off your shoes,
Put your feet up!
Lean back and just enjoy the melodies.
After all, music soothes even the savage beast.” – The Offspring

Thanks for reading 😘 !