DIY high-end Morel boombox build

If you are reading this article, you probably watched my YouTube video on how I made this speaker. Either you are curious on the exact components, or how I made this speaker, you will have to continue reading. Not only you will find the build plans for this high end portable Bluetooth speaker, but you will also find tips on how to make this speaker. Maybe even better than me, because I would change some things now that I finished it.

Parts list

First of all, let’s list all the parts which you will need. I will try to give sources for both, Europe and US, but bear in mind that you can swap whatever component with what you have readily available.

The links form Sound Imports, Amazon and Parts Express are affiliate paid links :

ItemEuropeUS
Morel Elite EW 536 (2 pcs)Sound ImportsParts Express
Morel Elite ET 448 (2 pcs)Sound ImportsParts Express
miniDSP 2×4 KitSound ImportsParts Express
Sure Electronics AA-AB32189 (2 pcs)Sound ImportsParts Express
Tinysine Bluetooth moduleAudiophonics
Precision Port 2″ (2 pcs)Sound ImportsParts Express
Monacor Ground Insulator (2 pcs)Sound ImportsParts Express
Monacor Strap HandleSound ImportsParts Express
TRACO POWER TRN 1-2412 12V Step down converterTMERS Delivers
AIMTEC AM1DR-0505S-NZ 5V – 5V IsolatorTMERS Delivers
AIMTEC AMSRW-7805-NZ 5V Step down converterTMERS Delivers
WAGO 222-415 splitter (2 pcs)TMEAmazon
INR18650-35E SAMSUNG SDI Li-Ion Cell (16 pcs)TMEIMR Batteries
Momentary switch GQ16PH-10/NTMEAmazon
Resistor 10 kOhmTMEAmazon
DC socket 2.1/5.5TMEAmazon
ON-OFF SwitchTMERS Delivers
BMSAmazon.deAmazon
Battery level indicatorAmazon.deAmazon
ChargerAmazon.deAmazon

Box design

First, let’s get to box design. The box is made of 10 mm thick MDF. You can’t really go any lower than that because these are not small speakers. Here are the panel dimensions :

  • Front / Back : 150 x 442 x 10 mm
  • Top / Bottom : 238 x 442 x 10 mm
  • Sides : 238 x 170 x 10 mm
  • Brace : 150 x 70 x 10 mm

Here is a schematic on how the panel fit to one another :

Box design sketch

The box also has 2 bass reflex ports and it’s tuned at 70 Hz.

High end portable speaker bass reflex port

To cut the ports to size, just make sure you get those 2″ precision ports and cut the tube to 115 mm in length. After that hook it to the exterior flare. Don’t use the interior flare as there is no room for it.

high end portable bluetooth speaker build

Just above we have the layout of the items. We have the amps on the sides. The bass reflex ports will be just above, and in the middle we will have the battery pack and the DSP. The grille in front is custom made. I’m sure you can find some metal working shop to cut it to size : 150 x 442 x 20 mm. There is much more to cover. However, in the end we will have a high end portable Bluetooth speaker in our hands.

Panel info

There is no nice way to put this. I’m just gonna list all the panels with the dimensions. After that, I will add some details where I feel it’s necessary.

Bluetooth speaker Front panel High end portable speaker Back panel 1 Back panel 2

Here are some explanations. If you can’t see clearly in the front panel sketch. The hole for the external antenna is 7 mm. You will have to find an SMA extension cable and a small antenna by yourself. However, make sure you get the right one, because some have pins in the middle, some have holes, and you have to match it correctly with the antenna you are buying, and the SMA connector on the Bluetooth module. You can easily confuse yourself and buy something that doesn’t fit. Or rather does fit, but doesn’t work

Back panel

Something I need to address about the back panel. The DC socket and the momentary push button which I use to trigger the pairing mode of the BT module, have insufficient thread for a 10 mm thick panel. And you can’t tighten the nut from the inside because there is no thread to hold on to. In that case, you need to make a recession marked by that rectangle. Since the panel is 10 mm thick, make sure it’s like 4 mm thick in that rectangle. The rest of items fit no problem. Note : Make sure you check the dimensions of the components you are buying because they might not be the same thing I used, and adjust the dimensions of the holes accordingly.

In the actual build, you also see me make an additional rectangle hole for the USB port. It isn’t marked in the schematic above. Just saw that, and I’m too lazy to correct it. This is to connect to the DSP after the box is made. This is optional, but I suggest you do it, if you want to make changes afterwards. Important note here : make sure you wire the external USB port correctly. You can plug it in the other way around and most likely smoke will come out of you DSP when you hook it to your laptop.

DSP USB wiring

Here is how the external USB wiring orientation should look like. Therefore, if you wire it like this you should have no worries.

An extra thing I want to mention about the side panel is that the hole for the bass reflex port is slightly off-set. As a result, when you place the side panel in place, make sure to place the hole closer to the battery pack and away from the speakers.

Circuit diagram

Here is how the circuit diagram should look like :

High end portable bluetooth speaker circuit diagram

Now I know it’s a lot to take in, but I will try to explain everything step by step.

Battery and BMS

The BMS is an universal 3S-13S BMS. At least, that is what it showed in the shop from which I purchased it from. On amazon it shows that it’s only 13S. Normally, that would only work with 13S battery packs, but the BMS looks identical, so I’m guessing it’s the same thing. As a result, instead of all the 13 sense wires, I only used 8. Because this is an 8S2P battery pack. Remember, this only works for universal BMS’s. You should search an 8S BMS, but they are hard to come by.

If you want to check out more about how BMS are wired, you can check another article of mine where I use the same BMS but with a 7S battery pack. We need a lot of voltage for this high end portable Bluetooth speaker. As a result, when the batteries are full, the voltage is 33.6V.

DC Socket and Charger

Next, we need to figure out how to charge this thing. The DC socket is nothing special, it just need to fit the DC jack on the charger. And the charger should be precisely 33.6V. In terms of current, 2A is fine.

ON/OFF Button

This deserves a separate section, because the amp and voltage rating on this button are important. To be on the safe side you should use at least an 8A button. Make sure you look at the DC ratings (because they are different from the AC). And the voltage should be at least 28V. Normally, it should be higher than 33.6V. But I used a 28V one and it worked fine.

If the button doesn’t have the correct amp rating, it will burn out in high loads. However, if the button has a too low voltage rating, something else happens, because voltage doesn’t burn the button. I used a 24V antivandal button, because it looks cool, but I haven’t got away with it. The voltage rating has to do with the switching capabilities of the button. If the rating is low, it cannot open the circuit fast enough. An electric ark forms between the poles and electrons pass, even though the circuit is open. As a result, you press the switch to turn off the speaker and it won’t shut off. That’s why you find that ugly green button at the end. I had to swap it. Antivandal buttons usually max out at 24V.

Battery level indicator

The battery level indicator needs to be set first. It has a button on the back. While you hook up the indicator to the battery for the first time, make sure you are holding the only button on the back. Then, you are in the config menu. Press the button until you find 8S. Then you can un-power the indicator. Then, next time you power it on, it will show the percentage of a 8S battery pack.

Step down converters

The battery is too high voltage to power the Bluetooth (which works at 5V) or the DSP (which works at 5-24V). For that reason we need step down converters to reduce the voltage to the appropriate level. I used a 5V step down for the BT module and a 12V one for the DSP. However, for the Bluetooth there is another isolator in series. It’s basically a 5V to 5V converter. This is to solve any ground loop issues, so you don’t get any weird noises in your speakers.

To be honest, I should of used isolators for the DSP as well, since I had problems with noise. Forgot about the DSP. However, I solved this issue with external ground loop isolators. I’ll get to them later.

BT button

This Bluetooth needs an extra button with 10 kOhm resistor in series to access the pairing function. This is not usually the case for most Bluetooth modules, so you probably won’t need one if you are using another module. It needs to be pressed twice to trigger the pairing function. The button doesn’t have to be something special, just a momentary push button.

RCA cables

To connect the BT to the DSP and the DSP to the amps, we are going to use RCA cables. RCA male to RCA male. For the connection to the BT module we are going to snip the RCA’s on one end and solder the wires directly to the module. For the connection between the DSP and amps we are going to use ground loop isolators which come with RCA cables built in. Take note that the Monacor isolator I listed has RCA female on one end so you will need some adapters.

Amps and wires

The amps have some gain toggle switches. So make sure you set the correct gain before you place them inside the box. Otherwise, you might be wondering why the volume is so low. Also, when it comes to the wires, make sure you separate the power wires from the signal wires. Otherwise, noise can be introduced from the power wires to the signal wires and you will have a bad time.

DSP programming and crossover point

If you payed close attention the the YouTube video. You see me do some measurements, and settings in the DSP. I measured the tweeters by themselves, and I noticed a dip at 3 kHz. This can be caused by 2 things :

  • The tweeters are too close to one another and are interacting destructively.
  • The rough 2 cm edge creates an unwanted reflection that creates a cancellation at 3 kHz.

For this reason, I decided to make the crossover point higher, since the mid-bass does not exhibit this behavior. Therefore, I setup the crossover point at 3750 Hz and the dip is gone.

For the rest of the EQ I will upload the file (Right click + Save link as) so you can use it directly. Take note that I also use a high pass filter at 35 Hz on the bass drivers. You plan on not cranking the speaker up, I suggest you remove that.

High-end portable Bluetooth speaker result

In the end, let’s look at the frequency response and give some impressions.

1000$ DIY Portable speaker

As you can see the response is very flat and it goes linearly down to 70-80 Hz. This is indeed a high end portable Bluetooth speaker. It goes loud as hell if you want it to. And the battery life I can only estimate it to be around 8 hours of playing it at moderate-high volumes. I can’t really tell, because I’m not going to play this speaker for several hours at 75% hours to test it out, because it would be a pain. I would recommend this for the occasional party, it would be more than enough. Especially if it’s indoors.