The Quarterwave Knowledge Base
WAAT Audio is an authorized HOQS builder and the stateside home for the PARAFLEX catalog — the community-engineered family of high-order quarterwave loudspeakers developed by the High Order Quarterwave Society in Australia. This page gathers the entire published catalog in one place: every cabinet design, the full HOQS driver line, and the path from a free plan to a CNC-cut flat pack built here in the Americas.
Quarterwave loading, put to work
PARAFLEX cabinets load the driver into a network of tuned resonator paths — low-tuned and high-tuned sections working together — instead of a simple ported box. The payoff is considerably more acoustic output per cubic foot, with the newest generations adding Helmholtz band-stop chambers that clean up midrange artifacts older folded designs struggled with.
One system, several families
The library spans mid-tops and kick-tops through four subwoofer families — Type O (including the compact CRAM folds), Type R, the Type C “Classic” line, and the Type A compacts — plus a dedicated ELF design, with tunings running from 25 Hz up to 80 Hz depending on the job.
Open plans, proven by builders
HOQS PARAFLEX was founded in coordination with Matthew Morgan J, Dustin Morgan, and J Vansickle, then refined by a worldwide development community of test builders. Every plan is published free under Creative Commons BY-NC-ND 4.0, with revisions driven by real measurements from real builds.
Every published PARAFLEX cabinet
Specifications summarized from the official HOQS plan documentation. Sensitivity figures are averaged across the stated operating band; SPL figures are half-space at one meter with the reference driver noted in each plan.
PARAFLEX 2×8 Mid-Top V2
Compact trapezoid mid-top built around a pair of 8s. The complete drawing set is drawn for 15 mm sheet stock; the full detail lives in the free plan.
- Format
- Trapezoid
- Front
- 519 mm
- Rear
- 270 mm
- Body
- 459×681
PARAFLEX C-3DKT 1×12
A 150-liter trapezoid kick-top that pulls 111 dB of sensitivity from a single 12 — developed and verified by a team of more than twenty community test builders.
- Range
- 80–1k Hz
- Sens.
- 111 dB
- Peak
- 144 dB
- Weight
- ~47 lb
PARAFLEX G1V2 1×12
The refined single-12 kick-top. V2 introduces Helmholtz-tuned band-stop chambers that absorb midrange interference, on top of the low-tuned/high-tuned resonator layout that defines the family.
- Range
- 90–1k Hz
- Sens.
- 108 dB
- Peak
- 141 dB
- Weight
- ~48 lb
PARAFLEX Wide Style V2 2×12
Double-12 wide-body kick section. Band-stop chambers tame odd-order resonances for a smooth, tight midrange; crosses cleanly to HF at 800 Hz and takes a 70 Hz BW24 high-pass.
- Range
- 90–700 Hz
- Sens.
- 108 dB
- Peak
- 144 dB
- Weight
- ~70 lb
PARAFLEX CRAM 2×12 Type O V2
The small-format Type O workhorse. V2 resolves the earlier 130 Hz response dip and extends usable output to 180 Hz — plan for roughly 75% open-area grilles to keep the mouth breathing.
- Range
- 35–100 Hz
- Sens.
- 102 dB
- Peak
- 138 dB
- Weight
- ~82 lb
PARAFLEX Type O 35 Hz — Three-Cabinet Plan Set
One plan set, three cabinets: the 35 Hz Type O fold drawn for twin-15, single-18, and single-21 builds, each supplied as both PDF drawings and STEP CAD files for CNC work.
- Variants
- 3
- Tuning
- 35 Hz
- Files
- PDF+STEP
PARAFLEX CRAM 2×18 Type O
The flagship-scale double-18: 724 liters folded to deliver 140 dB continuous from a 30 Hz tune. Purpose-matched to the HOQS 18″ driver platform.
- Range
- 30–100 Hz
- Sens.
- 104.5 dB
- Peak
- 146 dB
- Weight
- ~180 lb
PARAFLEX 2×18 Type O “Playa Edition”
The forward-facing-driver rework of the double-18 (Revision 5), reaching down to 25 Hz — built for open-air, festival, and desert-scale deployments.
- Reach
- 25 Hz
- Volume
- 703 L
- Weight
- ~180 lb
PARAFLEX 2×21 Type O, Forward Drivers
The biggest fold in the catalog: a 796-liter double-21 with forward-facing drivers and 25 Hz reach, for when the job simply cannot be too large.
- Reach
- 25 Hz
- Volume
- 796 L
- Weight
- ~193 lb
PARAFLEX Type R 1×18
Single-18 Type R fold, matched to the HOQS 18″ driver platform. The complete drawing set is in the free plan; CNC files are available for kit production.
- Config
- 1×18″
- Family
- Type R
- Files
- PDF+DXF
PARAFLEX Type R 1×21
Single-21 Type R tuned at 30 Hz with usable output all the way up to 180 Hz — unusually wide bandwidth for a cabinet that digs this deep.
- Range
- 30–180 Hz
- Sens.
- 104 dB
- Peak
- 143 dB
PARAFLEX C-CRAM 2×15 Type C
Compact-fold Type C drawn for twin 15s. Everything you need to build one — panels, fold, and hardware callouts — ships in the free plan PDF.
- Config
- 2×15″
- Family
- Type C
- Files
PARAFLEX Type C “Classic” V1
The original 35 Hz Classic cube for single 18s and 21s, with published measured response. Superseded by V2 but still a proven, widely built cabinet.
- Range
- 30–110 Hz
- Sens.
- 103 dB
- Peak
- 141 dB
- Weight
- ~147 lb
PARAFLEX Type C “Classic” V2
The do-everything Classic, redrawn: one 502-liter cabinet covering configurations from 12″ through 24″ drivers. Twin B&C 15DS115s tune to 31 Hz; a single HOQS N216C tunes to 32 Hz.
- Range
- 30–100 Hz
- Sens.
- ~102 dB
- Peak
- 140 dB
- Weight
- ~154 lb
PARAFLEX Type A 1×12 V2
Compact single-12 quarterwave, published in both metric and imperial drawing sets — a 200-liter footprint that suits smaller rigs and first-time builders.
- Volume
- 200 L
- Weight
- ~101 lb
- Files
- PDF ×2
PARAFLEX C2E ELF
The deep-end specialist: 678 liters of extended low-frequency reach for single 18s and 21s, tuned at 28 Hz and proofed by a community test-build program.
- Range
- 28–120 Hz
- Sens.
- 105.5 dB
- Peak
- 144 dB
- Weight
- ~231 lb
The HOQS driver line
Purpose-built for PARAFLEX loading — FEA-modeled motors, carbon fiber cones on the LF units, and compliance profiles chosen for folded horn work. All models are 8 Ω. WAAT stocks and supplies HOQS drivers for the Americas; recone and diaphragm kits are available.
HOQS HF143N
1.4″ compression driver with a 3″ edge-wound aluminum coil, titanium diaphragm, and a copper shorting ring for distortion control. Cross at 800 Hz with a BW24 filter. Diaphragm kits available.
Full specifications
| Throat exit | 35.6 mm (1.4″) |
| Voice coil | 75 mm (3″) edge-wound aluminum, Kapton former |
| Flux density | 1.9 T |
| Recommended crossover | 800 Hz, BW24 |
| Dimensions | 125 mm OD × 55 mm deep · 102 mm bolt circle, 4× M6 |
| Net weight | 2 kg (4.4 lb) |
HOQS BH1 Horn
Point-source fiberglass horn designed as the HF section for PARAFLEX tops. Ships with a 1.4″-to-2″ throat adaptor; published response was measured with the HF143N on that adaptor.
Full specifications
| Dimensions | 567 × 372 × 310 mm (to 360 mm with adaptor) |
| Baffle cutout | 467 × 308 mm |
| Driver mount | 102 mm bolt circle, 4× M6 |
| Weight | 3.5 kg (7.7 lb) |
HOQS N62C
6″ carbon fiber cone mid with a 2″ OFC coil. High sensitivity, low distortion, and a compliance profile tailored to horn loading — the reference driver for the arrayable MidWave module.
Full specifications
| Fs / Re / Qts | 95.7 Hz / 5.5 Ω / 0.27 |
| Xmax / BL | 5 mm / 15 T·m |
| Vas / Sd | 3.95 L / 136.85 cm² |
| Le @1kHz / EBP | 0.389 mH / 353.7 |
| Power | 200 W nominal / 400 W program |
| Dimensions | 161 mm OD · 147 mm cutout · 83 mm deep · 1.96 kg |
HOQS N123
The reference 12″ for PARAFLEX kick-tops: FEA-modeled neo motor, weather-treated paper cone, 3″ two-layer OFC coil, and a light, high-compliance moving system built for horn-loaded mids.
Full specifications
| Fs / Re / Qts | 37 Hz / 5.8 Ω / 0.16 |
| Xmax / Xmech | 6.3 mm / 32 mm p-p |
| BL / Vas / Sd | 25.5 T·m / 97 L / 532 cm² |
| Le @1kHz / EBP | 0.79 mH / 231 |
| Power | 500 W nominal / 1000 W program |
| Dimensions | 320 mm OD · 281 mm cutout · 143 mm deep · 4.7 kg |
HOQS F185C
18″ carbon fiber cone sub driver on a 30 mm Y35 ferrite motor with a 5″ OFC coil and dual treated spiders. The ferrite twin of the N185C — same performance, more mass, less cost. Recone kits available.
Full specifications
| Fs / Re / Qts | 29.5 Hz / 5.7 Ω / 0.23 |
| Xmax / Xmech | 13.5 mm one-way / 56 mm p-p |
| BL / Vas / Sd | 34.54 T·m / 242 L / 1225 cm² |
| Mms / η₀ | 281.5 g / 2.11% |
| Power | 1700 W nominal / 3400 W program |
| Mounting | 442 mm bolt circle · 424 mm cutout · 21.5 kg (47 lb) |
HOQS N185C
The neodymium 18: same 5″ coil and carbon cone as the F185C at roughly 18 pounds lighter per driver — the pick when a double-18 cabinet already weighs enough. Recone kits available.
Full specifications
| Fs / Re / Qts | 29.5 Hz / 5.7 Ω / 0.21 |
| Xmax / Xmech | 13.5 mm one-way / 58 mm p-p |
| BL / Vas / Sd | 35.7 T·m / 242 L / 1225 cm² |
| Mms / η₀ | 281.5 g / 2.36% |
| Power | 1700 W nominal / 3400 W program |
| Mounting | 461 mm OD · 442 mm bolt circle · 424 mm cutout · 13.5 kg (30 lb) |
HOQS N216C
The 21″ flagship: 6″ OFC coil on a ventilated former, spaced dual spiders for controlled high compliance, carbon fiber cone. The first-choice driver for the largest Type O and ELF builds.
Full specifications
| Fs / Re / Qts | 29.46 Hz / 6 Ω / 0.30 |
| Xmax / Xmech | 13.5 mm one-way / 54 mm p-p |
| BL / Vas / Sd | 38 T·m / 290 L / 1669 cm² |
| η₀ | 2.374% |
| Power | 2000 W nominal / 4000 W program |
| Mounting | 545 mm OD · 522 mm bolt circle · 495 mm cutout · 20.9 kg (46 lb) |
Also in the line: the WG6 dual-1.4″ line-source waveguide and the N124C 12″ neo sub driver (the reference for the CRAM 2×12). Ask WAAT for current stock and pricing on any HOQS driver.
Three ways to get there
Build from the free plans
Every PARAFLEX design above links to its official free plan — full drawings, panel schedules, and driver recommendations, published by HOQS under Creative Commons BY-NC-ND 4.0 for personal builds.
Order a CNC flat pack
Skip the table saw. WAAT cuts PARAFLEX flat packs on CNC from the official geometry — every dado, brace, and driver cutout machined, labeled, and ready for glue-up, shipped anywhere in the Americas.
Have WAAT build it
Finished cabinets, assembled and finished in Sarasota — loaded with HOQS or spec-alternative drivers, wired, tested, and processed before they leave the shop.
A note on custom drafting: HOQS Australia has paused its custom DXF drafting service. For builders in the Americas, WAAT handles CNC file preparation and flat-pack production for the published catalog directly — reach out with the design you're after.
Start your build with WAATQuarterwave questions, answered
What makes a PARAFLEX different from a regular ported sub?
A ported (bass reflex) box uses one tuned resonance. PARAFLEX designs are high-order quarterwave systems: the driver works into a series of tuned resonator sections that stack their contributions across the passband. In practice that means noticeably higher output from the same driver and amplifier, at the cost of a more complex fold — which is exactly why CNC-cut kits exist.
What do Type O, Type R, Type C, and Type A mean?
They're distinct fold geometries within the PARAFLEX system, each drawn in multiple driver sizes. In the current catalog, the Type O family (including the compact CRAM folds and the forward-driver “Playa” editions) covers the highest-output builds with tunings from 25 to 37 Hz; Type R is the single-driver fold with unusually wide bandwidth; Type C “Classic” is the versatile all-rounder now drawn for everything from twin 15s to a single 21; and Type A is the compact entry point. The kick-tops and mid-tops apply the same resonator approach to the 80 Hz-and-up range.
Are the plans really free?
Yes. HOQS publishes every PARAFLEX plan free under Creative Commons BY-NC-ND 4.0 — you can download and build for yourself, but the plans can't be resold or modified-and-republished, and commercial production runs through authorized builders. That's the role WAAT fills for the Americas.
Why buy a flat pack instead of cutting my own?
PARAFLEX folds involve a lot of precisely angled panels, and small cutting errors compound — a path that's a few millimeters off changes the tuning you spent all that plywood chasing. A CNC flat pack gives you the exact published geometry with machined dados and driver cutouts, so the build becomes assembly and finishing instead of layout and re-cutting.
Do I have to use HOQS drivers?
No — every plan lists vetted alternatives from B&C, Beyma, 18Sound, Faital Pro, BMS, RCF, and others, and the published SPL figures name the reference driver used. That said, the HOQS line was engineered specifically for these cabinets (motor strength, compliance, and excursion matched to the fold), so it's the default we load and recommend. Stick to the listed models or ask before substituting: quarterwave cabinets are far less forgiving of driver swaps than reflex boxes.
How does WAAT relate to HOQS Australia?
HOQS is the design organization and worldwide community behind PARAFLEX; WAAT Audio is an authorized builder serving the Americas — supplying CNC flat packs, HOQS drivers, and finished cabinets built to the official documentation. Design credit for everything on this page belongs to HOQS and its development community; the deepest well of build knowledge is the HOQS Facebook group, where these designs were born and are still being refined.