Twiggy35

ENCLOSURE RECOMMENDATIONS: Twiggy35X8-535D
Driver: Twiggy35X8-535D (Twiggy35) — 3.5" ultra-shallow woofer, 8 ohm
Key T/S: Fs=145.0Hz, Qts=1.25, Qes=1.75, Qms=4.38, Vas=0.6L, Sens=83dB
Power: AES 10W / Cont 20W / Peak 40W
Xmax=0.25mm (linear), Xmech=2.75mm, Xprot=3.8mm
Sd=36.32cm², Bl=3.7T·m, Le=0.19mH
Depth: 10.15mm | Baffle cutout: 77mm | CCAW voice coil | Honeycomb paper cone

DESIGN HIGHLIGHTS AND REMARKABLE PROPORTIONS:
  - Total mounting depth: 10.15mm — approximately 4–6× shallower than a
    conventional 3.5" driver (typically 40–60mm)
  - Design cone excursion: 3.8mm (Xprot) — represents 37% of the total
    driver depth. This ratio is extraordinary; conventional speakers
    achieve Xmax of only 5–15% of total depth
  - Patented Twiggy suspension geometry allows the voice coil and cone
    to travel nearly 4mm within a chassis just over 10mm deep
  - CCAW (Copper-Clad Aluminum Wire) voice coil on aluminum former —
    minimizes moving mass for improved sensitivity within the severe
    depth constraint; CCAW reduces coil mass vs full-copper winding
  - 3-layer honeycomb paper cone — high rigidity-to-mass ratio, resists
    cone breakup through the upper frequency operating range, supports
    crossover to tweeter at up to 1.8 kHz
  - Le=0.19mH — very low inductance supports extended, flat response to
    the crossover point; clean handoff to tweeter
  - Steel basket — compact, cost-effective integration into thin product
    assemblies; lower weight than aluminum at this scale (95 grams total)
  - Neodymium motor — provides usable motor force within the extreme
    depth constraint; ferrite magnet not viable at this form factor

CROSSOVER REQUIREMENT:
  This driver requires a tweeter. Recommended crossover frequency:
  1.0–1.8 kHz (Linkwitz-Riley or Butterworth, 12–24dB/oct)
  The honeycomb cone maintains controlled response to ~1.8 kHz, above
  which higher-order breakup modes begin. A tweeter crossing in at
  1.2–1.5 kHz is recommended for best power response and imaging.

NOTES ON Qts=1.25 AND ENCLOSURE BEHAVIOR:
  With Qts=1.25, no practical sealed box volume produces a Butterworth
  (Qtc=0.707) or near-flat response. ALL sealed enclosure alignments
  for this driver exhibit a resonant peak at fc, ranging from ~+3dB to
  +12dB depending on box volume. This is inherent to the high Qts
  design — a trade-off accepted in exchange for the extreme thinness.

  DSP equalization is required in virtually all applications to produce
  flat frequency response. This is consistent with the target product
  categories (TVs, soundbars, automotive, conference systems) which
  universally incorporate DSP signal processing.

  Effective operating bandwidth: fc (application-dependent) to 1.8 kHz
  HP filter below fc is essential for excursion protection.
APPLICATION-SPECIFIC ENCLOSURE SCENARIOS
All enclosures are sealed (acoustic suspension). No vented/ported
designs are practical given the depth constraint. The dominant design
variable is the cavity volume achievable within the product depth budget.
SCENARIO 1 — TV / FLAT-PANEL DISPLAY
  Cavity Volume: 0.06 L (60 cm³)
  Example: 80mm × 50mm × 15mm cavity behind driver
  Qtc: 4.15
  fc: 481 Hz
  Total assembly depth: ~25mm (driver + cavity + backplate)
  HP Filter: 300 Hz (24dB/oct minimum)
  DSP: Mandatory — ~12dB cut at fc required for flat response
  Max SPL at 0.5m: ~96dB (10W AES)
  Notes: In a thin-bezel TV, the driver is typically rear-firing or
         downward-firing. At fc=481Hz the driver operates as a midrange
         in this application — bass content is either absent or boosted
         via psychoacoustic DSP (virtual bass enhancement). The shallow
         cavity is a feature, not a limitation: a pair of Twiggy35
         drivers fits within a 28–30mm TV chassis profile. Best results
         achieved with DSP shelf correction and HP at 300Hz.
SCENARIO 2 — SOUNDBAR
  Cavity Volume: 0.25 L (250 cm³)
  Example: 100mm × 50mm × 50mm cavity behind driver
  Qtc: 2.31
  fc: 267 Hz
  Total assembly depth: ~60mm (driver + cavity + rear panel)
  HP Filter: 150 Hz (24dB/oct recommended)
  DSP: Required — ~7dB cut at fc for flat response
  Max SPL at 1m: ~93dB (10W AES)
  Notes: A compact soundbar can accommodate a larger cavity than a TV,
         giving a more manageable fc and response peak. Multiple Twiggy35
         drivers in an array along a 60cm soundbar provide useful output
         from 150 Hz to 1.8 kHz, with a tweeter array handling the
         remainder. The 10.15mm driver depth easily fits in any soundbar
         ≥18mm deep. DSP correction to flat above 150Hz is straightforward
         with modern soundbar processor chips.
SCENARIO 3 — CONFERENCE ROOM TABLE SPEAKER / DESKTOP DEVICE
  Cavity Volume: 0.6 L (600 cm³)
  Example: 120mm × 100mm × 50mm cavity (or distributed volume)
  Qtc: 1.77
  fc: 205 Hz
  Total assembly depth: ~60mm device height
  HP Filter: 100 Hz (24dB/oct recommended)
  DSP: Beneficial — ~5dB shelf correction below 200Hz
  Max SPL at 0.5m: ~96dB (10W AES)
  Notes: A flush-mount table speaker or conference speakerphone housing
         can achieve 0.6L cavity volume while maintaining a slim profile.
         At fc=205Hz, the response peak is in the upper bass range and
         is easily corrected by DSP. The driver covers 100Hz–1.8kHz
         effectively with equalization — suitable for voice reproduction,
         videoconferencing, and near-field audio. A pair (L+R) in a
         cylindrical or oval table-top housing provides clear, articulate
         speech reproduction at conference room distances.
SCENARIO 4 — AUTOMOTIVE: DOOR SKIN / DASH / A-PILLAR
  Cavity Volume: 0.15 L (150 cm³)
  Example: 100mm × 75mm × 20mm cavity in door skin
  Qtc: 2.80
  fc: 324 Hz
  Total assembly depth: ~30mm (driver + door skin cavity)
  HP Filter: 180 Hz (24dB/oct recommended)
  DSP: Standard in automotive — car audio DSP handles fc correction
  Max SPL at 1m: ~93dB (10W AES) — supplemented by rear channels
  Notes: The Twiggy35's 10.15mm depth allows installation directly into
         a 12–15mm door skin without breakthrough into the door cavity.
         This eliminates the acoustic coupling issues of door-cavity
         mounting. A-pillar and dashboard installations benefit from
         the minimal depth clearance requirement. In automotive systems
         with DSP head units, the fc=324Hz response peak is corrected
         automatically by EQ tuning. Crossover to tweeter at 1.2–1.5kHz
         provides full-range output within the front soundstage.
SCENARIO 5 — AUTOMOTIVE: HEADREST / HEADLINER / PARCEL SHELF
  Cavity Volume: 0.08 L (80 cm³)
  Example: 65mm × 50mm × 25mm cavity in headrest housing
  Qtc: 3.64
  fc: 422 Hz
  Total assembly depth: ~35mm
  HP Filter: 250 Hz (24dB/oct recommended)
  DSP: Standard
  Notes: Headrest-mounted speakers operate at very short listening
         distances (0.1–0.3m), so sensitivity requirements are modest.
         The 10.15mm depth is a critical enabler for headrest integration
         where even 20–25mm clearance is challenging with conventional
         drivers. At this distance, fc=422Hz is less audible as a peak
         due to the near-field listening position. Well-suited for
         active headrest audio (individual zone audio), conferencing
         in vehicles, and luxury automotive applications.
SCENARIO 6 — INFINITE BAFFLE / OPEN BACK / PANEL MOUNT
  Cavity Volume: N/A (no enclosure)
  Qtc: 1.25 (= Qts)
  fc: 145 Hz (= Fs)
  Total assembly depth: 10.15mm (driver only)
  HP Filter: 80 Hz (recommended to protect Xmech)
  DSP: Strongly recommended — ~4dB shelf correction below 145Hz
  Notes: When mounted in a large flat panel or baffle with open rear,
         the driver operates near its free-air parameters. At Qts=1.25,
         there is a moderate +4dB peak at Fs=145Hz, which DSP corrects
         readily. This is the thinnest possible assembly — 10.15mm total.
         Suitable for flat-panel PA speakers, architectural installations,
         and display-integrated audio where the rear of the panel is
         acoustically open. The driver loads into the room's acoustic
         impedance rather than a sealed cavity.
SYSTEM INTEGRATION SUMMARY
  Crossover to tweeter:  1.0–1.8 kHz (2nd or 4th order crossover)
  Driver operating band: HP filter cutoff to 1.8 kHz
  Sensitivity:           83 dB (1W/1m) — pair with tweeter of ~83–89dB
                         sensitivity for balanced levels
  Impedance:             8 ohm nominal (Re=7.3Ω)
  Max output (10W AES):  93dB at 1m / 99dB at 0.5m / 105dB at 0.25m

  All applications require DSP for flat frequency response.
  All applications require HP filtering to protect the driver
  from excessive excursion below the operating bandwidth.

  | Application      | Cavity | Qtc  | fc    | Total Depth | HP Filter |
  |------------------|--------|------|-------|-------------|-----------|
  | TV / flat panel  | 0.06L  | 4.15 | 481Hz | ~25mm       | 300Hz     |
  | Soundbar         | 0.25L  | 2.31 | 267Hz | ~60mm       | 150Hz     |
  | Conference/desk  | 0.60L  | 1.77 | 205Hz | ~60mm       | 100Hz     |
  | Auto door/dash   | 0.15L  | 2.80 | 324Hz | ~30mm       | 180Hz     |
  | Auto headrest    | 0.08L  | 3.64 | 422Hz | ~35mm       | 250Hz     |
  | Infinite baffle  | open   | 1.25 | 145Hz | 10.15mm     | 80Hz      |