--- instrument: Tromba Marina family: strings / bowed monochord readiness: L2 V5 build-packet candidate authority: concept study; pending measurement --- # Tromba Marina Design Study ## Concept This packet organizes a tromba marina as an L2 review candidate: enough subsystems and prototype work are named for planning, but nothing here is build-ready. The instrument identity still comes from three linked systems: - a long bowed string that favors natural harmonics; - a buzzing bridge with one foot deliberately loose against the soundboard; - optional sympathetic strings inside the body to add resonance. The design goal is to define the next evidence-gathering path without drawing a build-ready outline. The core questions are how the loose bridge foot buzzes without choking the string, how the player reliably finds harmonics, and how the body and optional sympathetic strings reinforce the sound without turning the bridge buzz into uncontrolled rattle. ## Mechanism Direction Candidate mechanism and structure families: - Trumpet bridge: an asymmetrical bridge where one foot transmits normal string load while the other is intentionally free or lightly coupled enough to buzz. - Harmonic playing surface: a neck or string path with visual or tactile reference marks for natural harmonics, pending historical and ergonomic review. - Resonant body: a tall hollow body or soundbox sized from future reference research, not from this concept packet. - Sympathetic strings: internal or hidden resonance strings that may be tuned after the main string plan is established. - Adjustable buzz control: future prototypes should test bridge mass, foot contact material, soundboard contact hardness, preload, and replaceable shims without claiming a final gap or angle yet. ## Parametric Intent Use named unknowns before any CAD or shop work: - `pending_body_length`: not specified. - `pending_string_scale_length`: not specified. - `pending_main_string_material`: not specified. - `pending_main_string_tuning`: not specified. - `pending_harmonic_reference_positions`: not specified. - `pending_bridge_height`: not specified. - `pending_bridge_loose_foot_gap`: not specified. - `pending_bridge_contact_material`: not specified. - `pending_soundboard_material`: not specified. - `pending_sympathetic_string_count`: not specified. - `pending_sympathetic_string_tuning`: not specified. ## L2 Subsystem Plan | subsystem | L2 candidate direction | authority | promotion evidence needed | | --- | --- | --- | --- | | Historical envelope | Select one or more reference instruments or drawings before any body layout. | pending_measurement | Cited source dimensions or a reviewed reference drawing. | | Main string path | Keep a single bowed string as the primary mechanism. | concept_only | String material, scale length, tension target, and anchor hardware chosen from references or bench tests. | | Buzzing bridge | Treat the loose-foot trumpet bridge as a replaceable experimental module. | pending_measurement | Bench-rig observations for buzz onset, sustain, wear, contact material, and reset repeatability. | | Harmonic references | Plan visual or tactile harmonic guides only after the string scale and tuning policy are chosen. | pending_measurement | Reviewed harmonic map derived from selected scale length and tuning plan. | | Resonator body | Keep the body form open until the historical envelope and bridge load path are reviewed. | pending_measurement | Reference body proportions, material stackup, soundboard support, and structural review. | | Sympathetic strings | Hold as an optional branch rather than the first prototype requirement. | concept_only | Decision whether they belong in the first full-body prototype, plus routing and tuning evidence if included. | ## L2 Prototype Path The first useful prototype is a buzzing-bridge bench rig, not a full instrument. It should hold a single tensioned string over an interchangeable bridge and a small soundboard coupon. The experiment should compare buzz onset, stability, string sustain, noise character, bridge wear, and whether the loose foot can be adjusted repeatably. After that, a separate resonance mockup can test whether sympathetic strings add useful bloom or only complicate setup. A future full-body packet should wait until those mechanism questions are answered and reference measurements are selected. ## L2 Review Checklist - Confirm the historical reference family and whether this packet is a modern workshop study or a closer reconstruction. - Choose the minimum buzzing-bridge bench rig that can test contact material, bridge mass, foot coupling, and reset repeatability without full-body dimensions. - Decide whether sympathetic strings are deferred or included in the first resonance mockup. - Create CAD only after reference measurements or bench-rig constraints are accepted as controlling inputs. - Keep all current drawings, tables, and prose at `concept_only` or `pending_measurement` until a later review supplies authority. ## Non-Claims This packet does not claim historical dimensions, tuning, harmonic node locations, bridge geometry, string tension, body material, soundboard thickness, or sympathetic-string layout. Those must come from future references, measurements, CAD review, and bench tests.