SpeaD 1.0 · Diaphragm

Diaphragm
Surround, Cone & Dust Cap

The moving diaphragm — surround, cone and dust cap — and the stiffness, mass and resonance they give.

Two views, one assembly

The Diaphragm page has two views. Surround designs the surround and predicts its stiffness against excursion. Cone Assembly designs the cone and dust cap that sit inside it and adds up the moving mass.

With Link Design ticked, the cone size and voice-coil diameter come in from Initial Design, and the moving mass, dust-cap mass, diaphragm Fo, Sd and the materials go back to it.

Surround

Six surround types — Half Roll, Inverted Roll, M-Roll, Accordion, Flat / Cloth and Tri-Radius — with cone size, outside diameter, active width, inner and outer lips, roll height, and rubber, foam and cloth materials from the database.

Stiffness comes from SpeaD’s store of finite-element (FEA) solutions of real surround shapes, scaled to your design and its material. Results give Kms and Cms at rest, Xmax(10) and Xmax(20), the break points where the roll leaves its linear range, and the surround mass. The displaced section is coloured by range, and where a stored FEA section matches the design it is drawn with its real deformed shape, coloured by stress.

SpeaD Diaphragm page, Surround view, with geometry inputs, neutral and displaced sections, slider and results
The Surround view — geometry on the left, neutral and displaced sections in the middle, results along the bottom.

Cone Assembly

Straight, simple-radius or curvilinear cones; concave, convex or flat dust caps, with a two-material sandwich option for flat caps. The strip gives the surround, cone and dust-cap masses, the moving diaphragm mass, the cone Fo and the surround’s Xmax(10) and Xmax(20). With the spider’s neck set to Up + Trough, Link Spider seats the cone neck in the spider trough.

SpeaD Cone Assembly view with a straight cone, convex dust cap and half-roll surround, dimensioned
The Cone Assembly view — a straight cone, convex dust cap and half-roll surround at rest.

Files and drawings

Save and open surrounds, cones, dust caps or the whole diaphragm assembly as SpeaD component files, exchange supplier workbooks, and open a dimensioned surround or cone-assembly drawing with a title block to print, export to PDF or copy.

With both the Spider and Diaphragm linked, the combined spider-plus-surround Kms(x), the XC50 excursion limit and fs(x) and Qts(x) appear on the Assembly Drawing and Nonlinear Curves pages.

Read the Diaphragm chapter of the SpeaD Owner’s Manual for every control on the page.