Daily Driver — Design Spec

Design Specification · v0.2 · 2026-06-12 — the functional spec the CAD is built against, and the reference behind the build guide, the parts list, and the measurements.

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Status: Design phase — CAD in progress. This document is the functional spec the CAD is built against, and the reference behind the build guide, the parts list, and the measurements.

Source: The CAD, STLs, headband DXF, and this spec are developed in the open at github.com/makerphones/daily-driver — the canonical home for the design files.

Overview

The Daily Driver is the canonical first build: a 40 mm open-back headphone that’s forgiving to design and to assemble, buildable by a first-timer, and good enough to keep wearing once it’s done. It’s fully parametric and built to be modified — change the driver, the pad, or the head size and the model follows. A pre-sourced kit may be offered later; everything here is also exactly what you need to build it yourself. For the same architecture as a hands-on walkthrough, see the simple open-back build.

Honest sonic target: a bright, open, detailed open-back — strong mids and treble, modest bass. That’s the nature of a small driver in an open baffle, and the design leans into it rather than chasing sub-bass the hardware can’t make.

System architecture

Four printed/sourced parts per side, each interface independently iterable:

SPRING STEEL ARC  (sourced, laser-cut flat, formed over a jig)
        |
SLIDER × 2  (printed) — adjusts length, wraps the arc, carries the yoke pivot post
        |
YOKE × 2  (printed) — connects slider to cup, allows ±20° tilt
        |
CUP ASSEMBLY × 2  (printed: cup shell + separate baffle plate)

Keeping each interface separate means any one part can be reprinted and iterated without touching the others.

Acoustic approach (open-back)

Open rear. The back of the cup is an open vent pattern, not a sealed chamber — that’s what makes the design forgiving and gives the open, airy character.
Front cavity = pad depth. Driver-to-ear distance is set by pad thickness — see ear pads and comfort for why. Deeper is more comfortable and slightly warmer; shallower is more present and brighter. This is the main tuning lever, and it’s why the pad choice is locked into the spec.
Light rear damping. A disc of acoustic felt or thin open-cell foam across the rear vent tames cone breakup and reflections — damping materials covers the options. Start light, tune by ear and measurement.
No sealed volume to get right — the reason an open-back is the right first build.
Expected response: forward mids, extended/airy treble, gentle rolloff in the low bass.

Design decisions

Cup shell

Symmetric — identical left and right; L/R marked in the surface only.
~90 cc internal acoustic volume — starting point, parameterized for easy adjustment (the reasoning lives in acoustic chambers and enclosures).
Open-back vent — ring of 6–8 oval slots on the rear face, ~40% open area.
Pad attachment — tension-ring lip, 61–62 mm OD to accept Brainwavz HM5 and compatible pads.
Walls — 3 mm minimum shell, 4 mm at structural points (baffle flange, yoke boss).
Print orientation — open face down, no supports.
Material — PLA+ for prototyping, PETG for durable/kit parts.

Baffle plate

Separate from the cup — 4× M3 screws into heat-set inserts; removable for driver swaps and tuning.
Driver cutout — acoustic aperture only; the driver sits on a ledge (the frame doesn’t pass through).
Gasket channel — 2 mm wide × 1.5 mm deep around the driver cutout.
Insert placement — 4 inserts, symmetric, ~70% of radius from center.
Cable entry — 6–7 mm hole near one edge, toward the headband side.
Print orientation — flat, no supports.

Yoke

Separate from the cup — lets the cup and yoke iterate independently.
Own pivot spec — a 6 mm-diameter post, deliberately not cross-compatible with commercial (e.g. Beyerdynamic) yokes; this is the project’s own interface.
Pivot post — 6 mm diameter, 8 mm tall, one flat face, M3 through-hole for a retention screw.
Rotation — ±20° tilt, with hard stops in the geometry to protect the cable.
Single axis — tilt only; no fold mechanism on v1.
Left/right — mirror images, two files.

Slider

Wraps the spring steel arc on three sides.
Adjustment — friction clamp: a printed spring arm presses on the steel face.
Detent-ready — the boss geometry also works with punched holes in the steel for a click-fit upgrade.
Carries the pivot post — 6 mm post matching the yoke bore, M3 retention screw.

Cable

Dual entry — each cup has its own exit; Y-split at chin level. No routing through the headband arc — simpler wiring, easier assembly.
Strain relief — raised ring at the entry; jacket clamped before it enters the cup.

Component specifications

Driver (parametric)

Design the baffle around named parameters, not a fixed part. Confirm the real numbers with calipers and print a baffle test piece (a ~20-minute print) before committing a full cup set.

Parameter	Starting value	Notes
Outer frame diameter (`driver_od`)	42 mm	38–42 mm class; measure your actual driver
Acoustic aperture (`driver_aperture`)	35 mm	Driver sits on the ledge inside this
Gasket ledge width	3.5 mm/side	(`driver_od` − `driver_aperture`) / 2
Driver depth	10 mm	Sets minimum cup interior depth
Cutout tolerance	+0.3 mm	Actual cut ≈ 35.3 mm for fit
Impedance target	32 Ω	Works from phones/laptops, no amp

Selecting a driver. The driver selection guide has the full method; for this design look for: 40 mm nominal, 32 Ω, neodymium magnet, a smooth response without aggressive peaks above ~3 kHz, and ideally a published measurement from another builder. Good options sit in the $12–18 range at Parts Express or Madisound.

Budget option, with a caveat. The Dayton CE38MB-32 (~$3.49, 40 mm frame, 32 Ω, Ø35.5 mm opening, ~5.6 mm deep) is the cheapest way in, but it has a peaky upper midrange that takes extra damping work to tame — workable, but not the easiest first-build driver. Choose it only if cost is the priority, and expect to spend more time on damping.

Ear pads

Brainwavz HM5 velour, 90 mm oval (widely available; the design is built to this pad).
Friction-ring attachment — pushes over the cup’s pad lip.
Confirm the HM5 inner ring diameter with calipers before finalizing the lip OD (nominal ~60 mm; cup lip OD target 61–62 mm).

Spring steel arc

Parameter	Value	Notes
Material	1095 high-carbon spring steel	Standard headband material
Thickness	0.7 mm	0.6 mm lighter/gentler, 0.8 mm firmer
Width	10 mm	Standard headband width
Target inside arc radius	~100 mm	Needs prototype iteration (see Open questions)
Developed (flat) length	~370 mm	~100 mm radius × ~90° arc + 30 mm terminations each end
Detent holes (optional)	3 mm dia., 6 mm spacing	Punched at cut time for click-adjust

Sourcing the steel — the clever part. Draw the arc as a flat developed profile (imagine the arc unrolled), export a DXF, and order it laser-cut in 1095 spring steel from a service like SendCutSend (~$10–15 delivered at low quantity). They ship flat precision blanks; you form the curve cold over a printed radius jig. No metal shop, no minimum orders. (Builders on a tighter budget can salvage spring steel from a cheap fashion headset — functional, but imprecise.) The DXF ships alongside the STLs so anyone can order their own.

3D-print guidance

Material: PETG (durable, slight flex — good for cups and the stressed gimbal/headband parts) or PLA+ (easy, rigid, fine for prototypes). Avoid brittle plain PLA on any stressed part.
Tolerances: start 0.2 mm clearance for a friction fit, 0.3–0.4 mm for a slip fit; tune to your printer.
Heat-set inserts: M3 brass inserts in printed bosses for any joint opened and closed (driver retention, gimbal) — far more durable than screwing into plastic.
Orientation: put the best surface on visible faces; print the grille flat; orient the yoke so stress runs along layer lines, not across them (layer adhesion is the weak axis).
Supports: designed to be support-free where possible (overhangs ≤45° chamfered).

Parametric setup (for builders who want to modify it)

The model is driven by named parameters so it can be adapted without re-modeling. Starting values:

cup_interior_diameter = 78 mm
cup_depth             = 30 mm
wall_thickness        = 3 mm
driver_od             = 42 mm     ← update when driver confirmed
driver_aperture       = 35 mm     ← update when driver confirmed
gasket_channel_width  = 2 mm
gasket_channel_depth  = 1.5 mm
pad_lip_od            = 62 mm
pivot_post_diameter   = 6 mm
vent_slot_count       = 7
vent_open_fraction    = 0.40

Cup approach — interior first. Model the acoustic void as the primary geometry (revolve the half-profile of the interior, then shell outward to wall_thickness), then add the pad lip, baffle flange, yoke boss, and vent array. Build order: cup → baffle → yoke → slider, each constrained by the part before it.

Printing the parts without your own printer

If you don’t have a printer, FDM print services (e.g. JLCPCB, Xometry) will print the part set inexpensively — order a few iterations at once to batch the shipping wait. For a show finish on the cups, an SLA service gives a smoother surface. Once a design is stable and you’re iterating often, an inexpensive desktop printer pays for itself quickly.

Bill of materials (build-it-yourself)

Component	Source	Est. cost
2× 40 mm driver, 32 Ω	Parts Express / Madisound	$8–18
1× Brainwavz HM5 velour pads	Brainwavz	$20–25
1× spring steel arc (laser-cut, formed)	SendCutSend + form	$8–15
8× M3 heat-set inserts	hardware/online	$1
8× M3×8 mm button-head screws	hardware/online	$1
Foam gasket tape (small roll)	hardware	$1
Damping pack (foam + felt + fiberfill)	Parts Express	$3–5
Cable + Y-split + 3.5 mm TRS plug	online	$8–15
Printed parts (2× cup, baffle, yoke, slider)	own printer or service	$3–25
Approx. total		~$55–105

Own-printer build lands near the low end (filament only); print-service sourcing near the high end.

Open design questions

These are the live problems still being worked — documented as the design develops.

Spring steel arc radius. Arc radius and steel thickness together set clamping force: too tight is uncomfortable, too loose falls off. Approach: print forming jigs at 95 / 105 / 115 mm inside radius, form a blank over each, test across head sizes before committing. Cold-formed spring steel springs back ~10–15% when released, so cut the jig radius 10–15% smaller than the target. If the best radius gives the wrong clamping force, change thickness (0.6 mm lighter, 0.8 mm firmer) before changing geometry.

Driver confirmation. The baffle is parametric specifically so the production driver can be locked late — update driver_od / driver_aperture and the baffle follows. Confirm a specific driver against the selection criteria above, ideally one with published measurements.

Locked vs. open — for the form/industrial-design work

Locked (the design must respect these):

The four-part architecture and the project’s own 6 mm pivot interface
Driver seat parametric to driver_od; baffle aperture to driver_aperture; grille protects the driver
Pad lip sized to the Brainwavz HM5 (61–62 mm OD)
Circumaural fit; spring steel headband, 1095 / 0.7 mm / 10 mm
Standard cable connector

Open (the form playground):

Cup profile and outer form
Rear vent geometry and pattern — the signature look
Yoke / slider styling within the pivot and clamp constraints
Color, finish, and overall aesthetic language

Design files license

The Daily Driver is open source, commercial use included. The hardware source — CAD, STLs, the headband DXF — is licensed CERN-OHL-P-2.0; this spec and the rest of the documentation are CC BY-4.0. Download, modify, build, and sell what you make — just credit Jamey Warren / Makerphones. More on the license page.

v0.2 · 2026-06-12 · Reconciled from the earlier Daily Driver brief and the driver-grounded acoustic spec. Update as the form lands and the first prototype is measured. Open decisions: specific production driver, final pad confirmation, connector choice. File license: CERN-OHL-P-2.0 (source) · CC BY-4.0 (docs).

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