An old friend mentioned that she was thinking of buying a large boombox to be used as a small PA and speaker for presentation duties in parties and festivals. Another friend who works in the pro sound was in the situation and we told her that we could build her a better speaker than the JBL Partybox she was thinking, just for the price of the parts.
Specs that were given:
-Battery powered
-Bluetooth and analog line in for dj mixers etc.
-Has to fit in the trunk of a small car
-Max 25kg
This will be the 3rd speaker that I've built, challenge accepted!
The 95% finished speaker, grills are temporarily attached because I didn't get all the parts when I ordered the smaller grills due to my mistake.
2x 8" Sica 8 D 1,5 CS full range speakers in ~10l closed compartments
B&C Speakers 10CL51 10" woofer in ~32l ported enclosure, calculated tuning frequency of 65Hz
JAB4 amplifier, 30W for the tops, 60W for the bass.
307Wh battery with selectable 12-24V
Due to weight constraints the enclosure is made from 9mm baltic birch plywood, front baffle and back of the bass enclosure has 2 layers. Supports are mostly from 20mm thick plywood strips, a lot of them have half lap style cut outs and/or grooves routed to the walls/parts to make it as sturdy as possible.
When you see the router as a spanking robot, you can't unsee it.
Front baffle miters and 2nd layer that fits inside the outer walls for more glue surface and stiffening.
On the left side, top and bottom of the enclosure, there are grooves for the closed compartment walls to slide into. Tight fit, had to hammer them in gently after a few rounds of fine tuning.
Better view of the routed groove and support structure for the ports being glued.
support grooves/rabets for the ports, which also work as carrying handles
Top view of the port connection structure
Better view of the layout
Had to use some screws during glue up to line the parts exactly.
The main glue up required some creativity to get the whole thing warm enough for the glue to dry, my basement workshop is pretty cold.
First testing before finishing touches. Banana for scale.
Battery and amplifier slot. I managed to measure this wrong, not twice but three times. Had to carve more room with a Dremel to get enough depth and make everything fit. The door has a piano hinge and magnets, which I don't have photos, the door closes with a satisfying click.
Rounding the port/handles before painting.
The bottom has 20mm plywood glued for extra support for 35mm pole adapter
I made potentiometer hats for the amp from red oak and merbau
After painting and lacquer just before attaching the elements.
She is very happy about the speaker.
Some minor flaws here and there but I'm mostly happy how this turned out. This doesn't sound like an off the shelf bluetooth boombox, this sounds and feels like a small PA top. I didn't do any measurements (yet) but from the feedback I got from my group of friends who participated on the first outdoor pressure test, everyone was surprised how punchy, physical and fat but not bloated the speaker sounds. The group has combined experience of 200+ years of party organizing, djing and pro audio and aren't afraid to point out any flaws. Needs some taming on 500-3000Hz range, a bit shouty before any eq with just digital crossover. The bass enclosure tuning is very close to the VituixCAD simulated/ calculated ~65Hz. When I tried this in my acoustically treated listening room and put it in a spot that wakes a 63-65Hz room mode, my attic hatch in the ceiling started to rattle with the bass. Can't turn the amplifier to half volume or something starts to rattle.
One guy who has a lot more experience on building speakers was suspicious when I told him it is made mostly from 9mm plywood and weights just shy of 25kg, I asked him to knock around the enclosure and he just started to laugh and kept knocking, it is surprisingly stiff and only slightly vibrates when playing as loud as the amp can handle.
Pardon for "scrolling arthritis" due to the amount of photos.
Specs that were given:
-Battery powered
-Bluetooth and analog line in for dj mixers etc.
-Has to fit in the trunk of a small car
-Max 25kg
This will be the 3rd speaker that I've built, challenge accepted!
The 95% finished speaker, grills are temporarily attached because I didn't get all the parts when I ordered the smaller grills due to my mistake.
2x 8" Sica 8 D 1,5 CS full range speakers in ~10l closed compartments
B&C Speakers 10CL51 10" woofer in ~32l ported enclosure, calculated tuning frequency of 65Hz
JAB4 amplifier, 30W for the tops, 60W for the bass.
307Wh battery with selectable 12-24V
Due to weight constraints the enclosure is made from 9mm baltic birch plywood, front baffle and back of the bass enclosure has 2 layers. Supports are mostly from 20mm thick plywood strips, a lot of them have half lap style cut outs and/or grooves routed to the walls/parts to make it as sturdy as possible.
When you see the router as a spanking robot, you can't unsee it.
Front baffle miters and 2nd layer that fits inside the outer walls for more glue surface and stiffening.
On the left side, top and bottom of the enclosure, there are grooves for the closed compartment walls to slide into. Tight fit, had to hammer them in gently after a few rounds of fine tuning.
Better view of the routed groove and support structure for the ports being glued.
support grooves/rabets for the ports, which also work as carrying handles
Top view of the port connection structure
Better view of the layout
Had to use some screws during glue up to line the parts exactly.
The main glue up required some creativity to get the whole thing warm enough for the glue to dry, my basement workshop is pretty cold.
First testing before finishing touches. Banana for scale.
Battery and amplifier slot. I managed to measure this wrong, not twice but three times. Had to carve more room with a Dremel to get enough depth and make everything fit. The door has a piano hinge and magnets, which I don't have photos, the door closes with a satisfying click.
Rounding the port/handles before painting.
The bottom has 20mm plywood glued for extra support for 35mm pole adapter
I made potentiometer hats for the amp from red oak and merbau
After painting and lacquer just before attaching the elements.
She is very happy about the speaker.
Some minor flaws here and there but I'm mostly happy how this turned out. This doesn't sound like an off the shelf bluetooth boombox, this sounds and feels like a small PA top. I didn't do any measurements (yet) but from the feedback I got from my group of friends who participated on the first outdoor pressure test, everyone was surprised how punchy, physical and fat but not bloated the speaker sounds. The group has combined experience of 200+ years of party organizing, djing and pro audio and aren't afraid to point out any flaws. Needs some taming on 500-3000Hz range, a bit shouty before any eq with just digital crossover. The bass enclosure tuning is very close to the VituixCAD simulated/ calculated ~65Hz. When I tried this in my acoustically treated listening room and put it in a spot that wakes a 63-65Hz room mode, my attic hatch in the ceiling started to rattle with the bass. Can't turn the amplifier to half volume or something starts to rattle.
One guy who has a lot more experience on building speakers was suspicious when I told him it is made mostly from 9mm plywood and weights just shy of 25kg, I asked him to knock around the enclosure and he just started to laugh and kept knocking, it is surprisingly stiff and only slightly vibrates when playing as loud as the amp can handle.
Pardon for "scrolling arthritis" due to the amount of photos.
This is really nice, well done!
What is the battery, does it have different voltages available by default?
And how was your experience programming the DSP?
I haven't paid attention to the Sure/Wondom amps for a while but something sparked my interest in them recently with the expanded options of recent models so I'm curious to learn how they're fairing in new builds
What is the battery, does it have different voltages available by default?
And how was your experience programming the DSP?
I haven't paid attention to the Sure/Wondom amps for a while but something sparked my interest in them recently with the expanded options of recent models so I'm curious to learn how they're fairing in new builds
Thanks!
The battery is Sandberg Survivor Powerbank 8in1 96000 (307Wh, 16x 32700 3.2V cells), I was thinking of making a custom battery for this but ended up with this "double idiot proof" solution to minimize electrical and fire hazards. It has selectable 12V/16.5V/20V/24V DC output, (max 84W) and can be charged straight from a solar panel, USB-c or DC charger. Definitely not the cheapest solution but very simple to use and has a lot of features to be used as regular camping/festival powerbank.
I didn't have time to program the DSP other than setting a highpass filter to protect the woofer by modifying the stock dsp provided by Sure/Wondom. I have absolutely zero experience on "coding/programming" dsp but still managed to make sense of it, took a bit of learning to familiarize myself with the Sigma studio and all the terminology. My friend is doing the rest of the overall system tuning/eq.
You can download the stock dsp program for the amplifier and look how everything is organized/routed, there is quite much you can do with the programmer and the library of drag & drop modules in Sigma studio is more than enough for basic dsp duties.
Only serious flaw is with the bluetooth, I think there is no easy way of setting a password for the connection, it has to be either pre programmed by Wondom or needs a dedicated board to change the name and password.