HELIX Ci7 W200FM-S3
Best box: 16.6 L bass reflex tuned to 44.2 Hz · F3 62.9 Hz
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Comparable 7.0" Drivers
Drivers with similar piston area, resonance and Qts — useful alternatives when the HELIX Ci7 W200FM-S3 does not fit your target box volume or tuning. Each entry links to its full enclosure design and Thiele/Small parameters.
⚠️ Engineering Notice for Builders
- Limited linear excursion (Xmax: 3.9 mm); set a high-pass subsonic filter at 25–30 Hz when driven with high power.
Recommended Bass Reflex (Vented)
PORT BUILDABLE| Net Box Volume (Vb) | 16.6 Liters |
| Tuning Frequency (Fb) | 44.2 Hz |
| F3 (-3 dB Cutoff) | 62.9 Hz |
| F6 / F10 Extension | 52.0 Hz / 40.0 Hz |
| Port Inner Diameter | Ø 5.0 cm |
| Port Physical Length | 14.6 cm |
| First Pipe Resonance | 1180.0 Hz |
| Estimated MOL @ F3 | 107.0 dB SPL |
Sealed (Acoustic Suspension) — compromise
SUITS INFINITE / OPEN BAFFLEWith Qts 0.69 a Butterworth (Qtc 0.707) box would be many times Vas. A box equal to Vas reaches Qtc 0.976; for a flat response this driver is better used on an infinite (IB) or open baffle.
| Net Box Volume (Vb) | 20.8 Liters |
| System Q (Qtc) | 0.976 (above Butterworth) |
| System Resonance (Fc) | 73.5 Hz |
| F3 (-3 dB Cutoff) | 61.4 Hz |
| F6 / F10 Extension | 50.5 Hz / 40.3 Hz |
| Air Spring Linearity | High (Zero port compression) |
Thiele/Small Parameters
| Resonance (Fs) | 52.0 Hz |
| Total Q (Qts) | 0.69 |
| Electrical Q (Qes) | 0.779 |
| Mechanical Q (Qms) | 6.04 |
| Equivalent Volume (Vas) | 20.8 Liters |
| Diaphragm Area (Sd) | 201.0 cm² |
| DC Resistance (Re) | 3.0 Ω |
| Efficiency Bandwidth Product (EBP) | 66.8 |
| Linear Excursion (Xmax) | 3.9 mm |
| Thermal Power (Pe) | 150.0 W |
| Nominal Diameter | 7.0" |
| Catalog Source | Load Forge catalog (manufacturer datasheets and retailer listings) |
Frequently Asked Questions
What is the recommended ported (bass reflex) box volume for HELIX Ci7 W200FM-S3?
Load Forge's calculated alignment puts HELIX Ci7 W200FM-S3 in a 16.6 liter vented enclosure tuned to 44.2 Hz, reaching an F3 cutoff of approximately 62.9 Hz.
Can HELIX Ci7 W200FM-S3 be used in a sealed box?
Yes. In a sealed (acoustic suspension) enclosure of 20.8 liters with a Qtc of 0.976 (above Butterworth), the system exhibits an F3 of 61.4 Hz.
What port dimensions should be used for HELIX Ci7 W200FM-S3 to avoid port chuffing?
Sized from cone displacement (Sd × Xmax), a minimum port diameter of 5.0 cm with a length of 14.6 cm is suggested; check the port air velocity at your drive level in the Load Forge Studio.
Shareable Acoustic Card for Forums & Social Media
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