--- instrument: Glass Harp family: idiophone_friction_glass packet_mode: v5_l2_candidate authority: concept_only / pending_measurement readiness: L2 V5 build-packet candidate --- # Glass Harp Design Study ## Design Thesis The glass harp is a friction idiophone made from individual wine glasses. The player wets a finger and circles the rim, causing stick-slip excitation of the glass. Pitch is selected by the glass and adjusted in practice by water level, but this packet does not claim any pitch table or fill-height relationship. The useful first step is not fabricated geometry. It is a disciplined test plan: choose candidate glasses, label them, measure their dry and filled response, record water levels consistently, and design a spill-safe playing surface. ## Mechanism Each glass acts as its own resonator. The player provides a controlled wet finger contact at the rim. Water changes the effective vibrating system and also changes playing feel, stability, and spill risk. The setup therefore needs a layout, labeling method, filling workflow, and measurement log before any musical scale claim is made. ## Mechanism Analysis The glass harp has no single body to dimension. Its behavior is the sum of many individual resonators plus a player's wet-contact technique. The L2 review therefore treats every glass as an inventory item with its own identity, condition, dry response, filled response, and handling notes. A future packet should not group glasses into a scale until the set has been measured. Water is both a tuning variable and a risk variable. Adding water can shift response, change onset effort, make the rim harder to excite, and increase spill risk. The review workflow should separate dry-glass behavior from filled-glass behavior so a poor response is not misdiagnosed as only a tuning problem. The support surface is also part of the instrument. A tray or table that damps the bowls, lets them slide, hides labels, or makes spills hard to control can make a good glass set unplayable. Early support work should favor reversible layout mockups and water-safe labeling over permanent fixtures. ## Parametric Intent Future data tables should separate measured values from choices: - `glass_id` - `glass_source_status` - `rim_condition_status` - `dry_response_status` - `filled_response_status` - `water_level_record_status` - `onset_effort_status` - `sustain_status` - `spill_control_status` - `layout_ergonomics_status` All fields are currently `pending_measurement`. This repo does not infer pitch, diameter, water fill, or tuning behavior from prose, images, or memory. ## Engineering And Acoustic Reasoning The useful L2 model is relational, not numeric: - Glass identity, wall profile, rim condition, and material influence dry response. - Water volume, water-level reading method, and evaporation influence filled response. - Finger wetness, rim cleanliness, and hand pressure influence onset and sustain. - Tray material, pad material, and glass spacing influence damping, stability, and playability. - Labeling must survive moisture without becoming a false tuning authority. No frequencies, fill heights, diameters, wall thicknesses, or scale intervals are released here. Those belong in a measured glass inventory and validation log after real candidate glasses exist. ## Materials Reasoning - Candidate glasses should be selected for intact rims, repeatable response, and safe handling before musical role. - Water-measurement tools should favor repeatability and spill control over visual elegance. - Labels should be removable or replaceable until final glass IDs are stable. - Tray or pad materials should be tested for damping and slip resistance. - Towels, wetting vessels, and cleanup materials are part of the playing system, not afterthoughts. ## Failure Modes - A glass chips or cracks during handling or play. - Similar-looking glasses produce unrelated pitches or response envelopes. - Water-level readings are not repeatable after draining and refilling. - Labels loosen, smear, or imply unmeasured pitch authority. - The tray damps the glass or lets it walk during rim excitation. - Finger wetness and rim cleanliness dominate the perceived tuning result. - Session drift from evaporation or splashing invalidates a fill log. ## Tolerances As Questions - How repeatable is a measured fill after drain/refill cycles? - How much water-level drift is audible during a session? - How much tray damping is acceptable before sustain suffers? - How much glass spacing is needed for hand access without collisions? - Which label method survives wet handling without touching the rim? ## Authority Boundary - Concept authority: README, design notes, estimated BOM, and decision record. - Measurement authority: none yet. - CAD/DXF authority: none yet. - Tuning authority: none yet. Future photos or renders can document layout and playing posture, but they must not become sources for pitch, fill height, glass dimensions, or fabrication templates. ## Measurement Gates Promotion beyond L2 requires: - A real glass set labeled and measured one glass at a time. - A repeatable water-level recording method. - Dry and filled response logs for each candidate glass. - A safe table or tray layout that controls spills and keeps glasses stable. - A playability test for onset, sustain, hand spacing, and retuning drift. - A cleaning and storage plan that preserves labels and measured fill records. ## Risks - Small changes in water level, rim wetting, or finger pressure may shift response. - Similar-looking glasses may not behave similarly. - Spill risk can damage labels, surfaces, microphones, or electronics. - Overconfident scale claims can hide the need for measured tuning logs. - Glass breakage and sharp edges require a handling and disposal plan. ## L2 Boundary This file is an L2 review scaffold. It does not provide CAD, DXF, glass dimensions, water volumes, tuning frequencies, scale layout, tray geometry, or measured acoustic response.