These bluetooth headphones are an evolution of my wired design ( https://www.thingiverse.com/thing:2120892 ).
They only require basic soldering skills to build, all the parts can be easily and fairly cheaply sourced and most importantly, they sound awesome! Surprisingly awesome in fact!
Parts to purchase:
Heat gun (optional)
Scalpel, knife or wire strippers to strip wires
Misc basic tools
Print the following parts:
Baffle - Audio Side V4-7
Baffle - Power Side V4-7
Cover - Audio Side V4-7
Cover - Power Side V4-7
Print the baffles with the driver side facing upwards
While being very careful not to damage the fragile mylar film of the drivers, insert the drivers into the baffles, oriented as per the yellow circles.
Glue the drivers into the baffles with four 1/4″ (6mm) spots of glue, evenly placed around the perimeter of the driver. DO NOT glue around the full perimeter of the driver, as this will adversely affect the sound.
Let the glue is dry…
Top Tip: let the glue dry fully before placing the covers on, as it can leave a white residue.
Driver orientation and plasticine 'tuning'
Now for the secret sauce! In this enclosure, the Dayton Audio CE38MB-32 drivers are way too bass-heavy and lack high end detail, so we need to reduce the mids/bass to make it more equal to the treble. You may think more-is-more when it comes to bass, but there will still be plenty after completing this step. If you don’t believe me, do a back-to-back comparison.
Using plasticine or similar, roll a small amount into a sausage then block all but one of the holes under the black fabric on the back of the driver. The blue arrow in the picture above shows the non-blocked hole.
By bending them back and forth, break the terminals off one side of each momentary switch then insert the switches into the housing.
Insert the USB port and switch. They should stay in place without glue, but glue them if/where necessary.
Power side components in situ (note the battery charge module style has changed since this photo - I will update shortly)
Step 5: Prepare Headband
Cut 4 x approx 0.5m (1.6ft) lengths of hookup wire, two red, two black.
Using masking tape or similar, label both ends of one set 'power' and the other 'audio'.
Insert the wires into the slot that runs along the headband.
Cut the heatshrink to length - it should run from end stop to end stop.
Slide over the heatshrink and shrink with a head gun. Be careful to not apply too much heat and cause the headband to bend. Alternatively, you can use gaffer tape.
The headband needs to be covered, as I have had issues with them breaking due to chemical attack. Covering them is effective at preventing this.
Headband with wiring and heatshrink
Referring to the picture below, connect all the components that do NOT go through the headband. For the momentary switches, the supply terminal is '1V8'.
Top Tip: For bluetooth circuit board soldering, insert the cicruit board into the slot in the baffle, apply solder to the hole, then hold the soldering iron to the blob in the hole and insert the wire. Remove the soldering iron and hold the wire in place until the solder has solidified.
Optional: there is a hole beside the 'on' symbol for a 1.8mm LED as an 'on' indicator. Wire the LED in parallel with the bluetooth board (after the switch). You will also need to add a resistor in series with the LED to limit its current and voltage as per its specs:
R = (3.7 - Vf)/If where Vf and If are the rated forward voltage and current of the LED
If the bluetooth circuit board is hard to insert into the housing, make sure the QA sticker is removed. The battery and bluetooth circuit board should stay in place without glue, but glue in if necessary.
Thread the headband wiring through the baffle holes, cut to length and solder the connections. Then insert the headband into the baffles.
NOTE: the headband bends slightly inwards at the front side to better fit your ears. I recommend orienting the sides such that the switches are at the rear, for a 'cleaner' look when you are wearing them.
Power and volume control wiring layout
Audio side wiring with circuit board in situ, before headband insertion
Power side with battery and headband in situ
Fit the cusions, covers and, pieces of fabric that go on the baffle under the cushions. Power on, pair and enjoy!
From experiance, they seem to take about 45 minutes to burn in and sound really awesome.
If the cushions don't sit flat on your ears, soften the headband with a heat gun and bend to fit.
I plan to keep evolving the design, so if you have any suggestions, please leave them in the comments below and go to http://homebrewheadphones.com/ to see the latest evolution of the design.