Fat Channel Plugin Selection Guide

Purpose: Advise AI agents on selecting the right compressor and EQ model for a given channel or mix target on the StudioLive 32SC Fat Channel.

Related files:

• classID_Mapping.md — exact __classid GUIDs for scene file encoding
• sources.md — PreSonus reference PDFs

How to Use This Skill

When an agent needs to recommend or set a Fat Channel compressor or EQ:

1. Identify the source (kick drum, snare, bass, vocals, room, bus, etc.)
2. Identify the target (transparency, punch, warmth, glue, color, control, vintage character)
3. Select the compressor from the Compressor Selector table below
4. Select the EQ from the EQ Selector table below
5. Look up the `__classid` GUID in classID_Mapping.md for use in scene files

Compressor Models

Factory Models (always available — no add-on required)

#### STANDARD — Live Index 0 · {870D04F7-212E-4F9C-ADBB-39A97216433F}

• Character: Transparent, surgical, neutral VCA-style compressor
• Controls: Threshold, ratio, attack, release, makeup gain, key-filter, sidechain
• Sound: No harmonic color; reduces dynamics precisely without adding character
• Best for:
• Channels that need gain leveling without coloration (speech, acoustic guitar, piano)
• Any source where the goal is control, not character
• Podcasts, broadcast, PA spoken word
• Avoid when: You want vintage warmth, harmonic saturation, or "pumping" character

#### TUBE — Live Index 1 · {7F8A4262-D377-48E3-9D48-15D82C400A71}

• Character: Warm, smooth, program-dependent — inspired by vintage tube optical compressors (LA-2A/Vari-Mu style)
• Controls: Threshold, ratio, attack, release, output gain
• Sound: Adds subtle harmonic warmth; releases musically without sounding unnatural; slower transient response
• Best for:
• Lead vocals — smooths out peaks while retaining presence
• Upright bass or acoustic bass — adds warmth without killing transients
• Acoustic guitar — natural-sounding squash
• Mix bus on acoustic/folk/jazz sessions
• Avoid when: You need fast transient control or click/attack preservation (kick, snare top)

#### FET — Live Index 2 · {1F831EC1-B8AC-4EE9-AD53-54227AF53D58}

• Character: Fast, aggressive, punchy — modeled after FET limiters (UREI 1176 style)
• Controls: Threshold, ratio (4:1, 8:1, 12:1, 20:1), attack, release, makeup gain
• Sound: Extremely fast attack catches transients hard; aggressive at high ratios; "all-buttons" mode adds density and distortion
• Best for:
• Snare drum — classic crack and punch
• Room mics — slammed for the "Bonham" room sound
• Rap/hip-hop vocals — aggressive control
• Bass guitar DI — fast transient control with attitude
• Any source that needs "taming" with bite retained
• Avoid when: Smoothness and transparency are the priority

Add-on Models (Fat Channel Collection Vol. 1)

#### BRIT_COMP — Live Index 3 · {FEF33155-7A9E-4F4E-B209-CFE86DDAFC8E}

• Character: British VCA console compressor — inspired by SSL G-Bus / Neve-style bus compression
• Controls: Threshold, ratio, attack, release (program-adaptive), makeup gain
• Sound: Adds "glue" and punch; musical auto-release; cohesive without dulling transients
• Best for:
• Drum bus — the classic SSL "glue comp" trick
• Mix bus compression — binds elements together
• Guitar bus, keyboard bus
• Any stereo group that needs cohesion and impact
• Avoid when: You need precise surgical control; this is a coloring/gluing compressor

#### CLASSIC_COMPRESSOR — Live Index 4 · {C38F9E1A-0127-4BB8-9377-40C545A50328}

• Character: Versatile, polished VCA — studio workhorse with clean punch
• Controls: Threshold, ratio, attack, release, makeup gain
• Sound: Between the transparency of STANDARD and the color of BRIT_COMP; adds modest density
• Best for:
• Live bass guitar — controlled, punchy, clean
• Keys and synths — keeps levels even without obvious compression artifacts
• General-purpose "set it and forget it" compression on any live channel
• Backup vocals — even, polished levels
• When to choose over STANDARD: When you want slight density/punch added; CLASSIC adds a touch of character STANDARD does not

#### COMP_160 — Live Index 5 · {F0BD22BB-5FE8-4279-8B05-D089B4D7B0BB}

• Character: Fast, punchy, program-dependent VCA — modeled after dbx 160/165A
• Controls: Threshold, compression (ratio), output gain; attack/release are program-dependent
• Sound: No manual attack/release — reacts to the program material automatically; very transparent at moderate settings, tight and punchy when driven
• Best for:
• Kick drum DI or mic — fast, transparent control with impact
• Snare (especially bottom mic) — quick and clean
• Bass guitar — tracks dynamics without pumping
• Live drum overhead/room control
• Key difference from FET: Less aggressive, more transparent; dbx-style vs. 1176-style character

#### EVEREST_C100A — Live Index 6 · {23F9C088-08BE-4259-9DCE-38720AE5DE73}

• Character: Tube leveling amplifier — smooth, musical, vintage warmth with program-adaptive behavior (Vari-Mu / Chandler / Fairchild-adjacent)
• Controls: Threshold, ratio, attack, release, makeup gain
• Sound: Rich harmonic coloration from the tube circuit simulation; natural dynamic riding; very musical release that breathes with the material
• Best for:
• Lead vocal bus — smooth, warm, even
• Acoustic instruments (violin, cello, woodwinds) — adds body and warmth
• Mix or 2-bus leveling on acoustic/jazz/classical content
• Gentle program leveling where character and warmth are desired
• Avoid when: Surgical precision or transparency is needed; this is a coloring compressor

#### FC_670 — Live Index 7 · {85DD5632-A536-49FF-894A-9329FC1124E4}

• Character: Vari-mu tube compressor — modeled after the legendary Fairchild 670
• Controls: Threshold, time constants (program-adaptive), output gain
• Sound: Extremely musical; slow attack that "breathes" with the music; adds warmth, depth, and subtle harmonic richness; legendary for its smooth gain riding
• Best for:
• Stereo mix bus — classic "vintage glue"
• Drum overhead bus — tames transients while adding depth
• Acoustic piano — natural, musical dynamics
• Vocal bus with multiple singers
• Any source that should sound like it was recorded at Abbey Road in 1966
• Key distinction: The most musical, least "processed-sounding" compressor available; use when you want dynamics to breathe, not just be controlled

#### RC_500_COMPRESSOR — Live Index 8 · {6A372968-AFA7-4A3F-805D-A09A4AE15777}

• Character: Clean, modern VCA with musical response — studio-quality channel compression
• Controls: Threshold, ratio, attack, release, makeup gain, key filter
• Sound: Punchy and controlled without excessive coloration; sits between the transparency of STANDARD and the punch of FET
• Best for:
• Electric guitar — controls dynamics without killing pick attack
• Drum room mics — natural-sounding taming
• IEM and monitor mix channels — even, consistent level
• General live channel compression when STANDARD is too clinical
• Paired with: RC_500_EQ for a matched "RC 500 Channel Strip" workflow

#### TUBE_CB — Live Index 9 · {C3C32BBC-42E2-41A7-99B5-EA1D62F897B5}

• Character: Tube optical compressor with side-chain flexibility — Tube-Tech CL 1B inspired
• Controls: Threshold, ratio, attack, release, makeup gain, sidechain/key
• Sound: Warm, musical tube saturation with optical-style program-dependent behavior; smoother than FET but with more body than TUBE factory model
• Best for:
• Vocals (lead and backing) — warm, smooth, natural
• Bass guitar — warm tube character with good transient control
• Cello, violin, acoustic guitar
• Any source where warmth + control is the goal
• Key distinction from TUBE: More side-chain control options; slightly tighter optical response

#### VT_1_COMPRESSOR — Live Index 10 · {AF35E448-40EC-4C5A-A05C-B40A5AC0A42F}

• Character: Variable-mu tube compressor — Manley Variable Mu / Vari-Mu style
• Controls: Threshold, ratio (variable-mu, soft knee), attack, release, makeup gain
• Sound: Extremely smooth gain reduction; soft-knee characteristic makes compression nearly invisible until driven hard; rich harmonic saturation; never sounds harsh
• Best for:
• Mix/2-bus — the "final touch" compressor
• Full drum bus — adds body, depth, and subtle density
• Acoustic ensemble recordings
• Any situation where compression should be heard as "louder and fuller" rather than "compressed"
• Avoid when: Fast transient control is needed (use FET or COMP_160 instead)

Compressor Selector — Quick Reference

EQ Models

Factory Models (always available)

#### STANDARD EQ — Live Index 0 · {A0A8A068-14F0-4B04-BB6F-AF8329D0E8EE}

• Type: 4-band fully parametric EQ + HPF
• Character: Transparent, surgical, neutral — no harmonic coloration
• Bands: Low shelf, low-mid peak, high-mid peak, high shelf; each fully parametric (frequency, gain, Q)
• Best for:
• Surgical problem-solving (narrow cuts for resonances, feedback frequencies)
• When source material needs correction, not color
• High-Q cuts for feedback modes or room modes in live sound
• Any channel where transparency is the goal
• When to choose over vintage models: When you need precise, problem-solving equalization

#### PASSIVE EQ — Live Index 1 · {C0730CBB-5135-4558-9222-C40BDBA036ED}

• Type: Passive EQ — Pultec EQP-1A inspired
• Character: Warm, musical, vintage; famous for the "Pultec trick" (boost and cut simultaneously at the same frequency for enhanced bass punch)
• Controls: Boost and attenuate at specific frequencies; program-adapted bandwidth curves
• Sound: Gentle, rounded curves; cannot be surgical; adds musical width and warmth; shelves have a characteristic musical rise
• Best for:
• Bass guitar — bottom-end enhancement
• Kick drum — classic Pultec bass boost
• Acoustic guitar — airy top-end with passive high shelf
• Mix bus — broad, musical tonal shaping
• Vocals that need warmth without obvious EQ
• Avoid when: You need precise, narrow corrections; passive EQs are broad and musical, not surgical

#### VINTAGE EQ — Live Index 2 · {E1C5E024-C5CD-473C-B08A-6EC177812E01}

• Type: Vintage-character parametric — inspired by vintage console channel EQ topology
• Character: Adds harmonic character alongside frequency adjustment; musicality over precision
• Sound: Broad, musical curves; boost frequencies sound "better" than the neutral STANDARD EQ
• Best for:
• Vintage rock, blues, jazz sessions
• Electric guitar — adds body and presence
• Drum channels that need "vintage" warmth
• Vocals where you want both tonal shaping and character
• When to choose over STANDARD: When you want the EQ itself to add color, not just correct

Add-on Models (Fat Channel Collection Vol. 1)

#### ALPINE_EQ_550 — Live Index 3 · {CBDD0DD3-C5EF-495A-B4C7-92EC5E8FE146}

• Type: Fixed-frequency proportional-Q EQ — modeled after API 550 series (500-series console EQ)
• Character: Musical, punchy, "console" sound; proportional Q (narrower at high gains, wider at low gains)
• Controls: Fixed frequency selections per band; ±12 dB boost/cut
• Sound: The classic "American" rock sound; fast, decisive EQ; boosts sound open and present, cuts are clean
• Best for:
• Drums — the "classic rock drum sound" EQ
• Electric guitar — presence and cut
• Bass guitar — low-mid punch
• Snare drum — crack and mid presence
• Any rock, metal, or pop channel
• Key distinction: This is the "rock and pop workhorse" EQ; musical, fast to use, sounds great pushed hard

#### BAXANDALL_EQ — Live Index 4 · {B4D3497E-4B1C-4CFA-B859-A918C17CDA03}

• Type: Baxandall shelving EQ — classic hi-fi/broadcast topology
• Character: Very gentle, broad, musical shelves; cannot be surgical; extremely transparent at moderate settings
• Controls: Low shelf (bass), high shelf (treble); simple, broad
• Sound: Sounds "natural" — like the source is simply brighter or warmer, not equalized; best tonal shaping tool for full-range sources
• Best for:
• Broadcast speech — gentle tonal balance
• Acoustic piano — broad air and warmth
• Mix bus — overall tonal balance without color
• IEM mixes — comfortable high-frequency adjustment
• Any source that just needs "a bit more warmth" or "a bit more air"
• Avoid when: You need mid-band control or frequency-specific shaping

#### RC_500_EQ — Live Index 5 · {63ADDF9B-0EC7-430A-AEBE-62B4CB5FBBD6}

• Type: Parametric EQ — studio channel strip quality
• Character: Clean, musical, versatile; a step up in character from STANDARD without heavy coloration
• Controls: Fully parametric with good frequency range
• Sound: More musical and open-sounding than STANDARD; adds slight density and presence
• Best for:
• Electric guitar channel strip (paired with RC_500_COMPRESSOR)
• Drum channels that need precise but musical shaping
• Live sound where you need both control and musicality
• Paired with: RC_500_COMPRESSOR for a matched channel strip workflow

#### SOLAR_69_EQ — Live Index 6 · {03819C3F-DC16-4B7B-B521-14B4042192F2}

• Type: Vintage console EQ — Neve 1073 / classic British console inspired
• Character: Rich, warm, "British" character; EQ boosts sound musical and full; cuts are smooth
• Controls: Fixed frequency selections per band; HP filter; characteristic Neve-style curves
• Sound: The classic "British" sound — warm low end, present midrange, airy top end; adding EQ makes sources sound bigger and more present
• Best for:
• Snare drum — the classic Neve snare presence
• Vocals — warm, full, present
• Bass guitar — Neve-style warmth and punch
• Drum bus — richness and body
• Rock and pop recording/mixing
• Key distinction: If ALPINE_EQ_550 is "American punch," SOLAR_69_EQ is "British warmth and richness"

#### TUBE_EQ — Live Index 7 · {09B38119-3945-40D1-BA33-2FA19620DAB0}

• Type: Tube EQ — Pultec / Manley Massive Passive inspired
• Character: Rich harmonic saturation from tube circuits alongside EQ; very musical; adds depth and dimension
• Controls: Boost and cut controls with tube-circuit frequency shaping
• Sound: EQ curves interact with tube harmonics; boosting frequencies also adds warmth and richness; the EQ "opens up" the source rather than just adjusting level at a frequency
• Best for:
• Lead vocals — warmth, air, dimension
• Acoustic guitar — rich body and shimmering highs
• Electric piano / organ — depth and warmth
• Mix bus — subtle tube character with broad shaping
• Any source that sounds "thin" and needs "body and dimension"
• Avoid when: Precision is needed; tube EQs add character that may not be appropriate for surgical work

#### VINTAGE_3_BAND_EQ — Live Index 8 · {4635DE88-C3D2-4645-BC4D-8DFD116D6914}

• Type: 3-band vintage fixed-frequency EQ — inspired by classic SSL/API console 3-band sections
• Character: Simple, musical, fast to use; the 3-band format is optimized for fast live sound decisions
• Controls: Low shelf, midrange peak (semi-parametric), high shelf
• Sound: Musical, punchy, wide; great for broad tonal decisions; less flexible than full parametric but faster and more musical
• Best for:
• Live sound quick adjustments — fast, musical, effective
• Drum bus — broad shape without surgical fuss
• Guitar and bass — quick character shaping
• Backing vocals — simple broad adjustments
• When simplicity and speed matter more than surgical precision
• Key advantage: Simpler than 4-band; faster decisions; still musical and effective

#### VT_1_EQ — Live Index 9 · {A0FAF452-D664-4BA2-90FC-6BD4AC469B29}

• Type: Variable-tube EQ — Manley Massive Passive / tube parametric inspired
• Character: Deep tube warmth with sophisticated parametric control; adds dimension alongside frequency shaping
• Controls: Multi-band parametric with tube-circuit saturation
• Sound: Combines the precision of parametric EQ with the richness of tube harmonic character; boosts add "body" not just volume at a frequency; cuts remain clean
• Best for:
• Mix/2-bus — sophisticated final tonal shaping with character
• Lead vocal — dimension, air, warmth simultaneously
• Acoustic instruments that need tonal refinement with body
• Any source that sounds "digitally flat" and needs "analogue dimension"
• Paired with: VT_1_COMPRESSOR for a matched tube channel strip

#### BUS_EQ — Line index N/A (bus/aux/sub only) · {4B92A91C-C6FB-4F0F-AE51-841378E4F9CF}

• Channel types: Aux outputs, sub groups, FX buses — NOT for line input channels
• Character: Full-range bus EQ; optimized for output bus treatment rather than per-channel use
• Best for: Shaping monitor mixes (IEM, wedge), sub-group frequency balancing, FX return tonal adjustment

EQ Selector — Quick Reference

Decision Framework for Agents

When choosing models, apply this decision hierarchy:

1. Does the channel need correction (remove problems)?
   → STANDARD EQ + STANDARD or CLASSIC compressor

2. Does the source need punch and transient control?
   → Compressor: FET, COMP_160, BRIT_COMP
   → EQ: ALPINE_EQ_550, SOLAR_69_EQ

3. Does the source need warmth and musical character?
   → Compressor: TUBE, TUBE_CB, VT_1_COMPRESSOR, FC_670, EVEREST_C100A
   → EQ: PASSIVE, TUBE_EQ, VT_1_EQ, SOLAR_69_EQ, VINTAGE

4. Is this a bus / group / mix?
   → Compressor: BRIT_COMP, FC_670, VT_1_COMPRESSOR
   → EQ: VT_1_EQ, BAXANDALL_EQ, VINTAGE_3_BAND_EQ
   → Bus channels: BUS_EQ

5. Is this a matched channel strip?
   → RC_500_COMPRESSOR + RC_500_EQ  (punchy, modern)
   → VT_1_COMPRESSOR + VT_1_EQ     (warm, tube)

MCP Interface — Tools and Resources

Overview

The MCP server is read-only by default (ADR-005, REQ-NF-002). Fat Channel data is exposed exclusively through resources. No write tools for setting compressor or EQ models exist in the current version.

MCP Tools:     3 (none touch Fat Channel directly)
MCP Resources: 5 (2 expose Fat Channel data)
Write tools:   0 (intentionally absent — see Write Capability below)

MCP Tools (All Read-Only)

#### discover_mixers

Discovers StudioLive III mixers on the local network.

// Input schema (all fields optional)
{
  timeoutMs?: number   // positive integer, ms; default: 5000
}

// Returns: JSON array of mixer identity objects
[
  {
    deviceId: string,        // e.g. "StudioLive32SC-SD7E21010066"
    serial: string,          // e.g. "SD7E21010066"
    model: string,           // e.g. "StudioLive 32SC"
    firmware: string,        // e.g. "3.3.0.109659"
    role: "FOH" | "STAGEBOX" | "MONITOR" | "UNKNOWN",
    ipAddress: string,
    port: number
  }
]

Fat Channel relevance: None — use this first to obtain a deviceId for subsequent resource reads.

#### refresh_mixer_state

Reconnects to a mixer and rebuilds its state cache, including Fat Channel model decoding.

// Input schema (all fields required)
{
  deviceId: string   // from discover_mixers — e.g. "StudioLive32SC-SD7E21010066"
}

// Returns: JSON object
{
  success: boolean,
  channelCount: number,     // number of channels in refreshed snapshot
  capturedAt: string        // ISO 8601 timestamp of snapshot
}

Fat Channel relevance: After calling this tool, the channels resource will reflect the latest compModelName and eqModelName for every LINE channel. Call this before reading Fat Channel state if the mixer state may be stale.

#### validate_mixer_identity

Validates that a connected mixer matches an expected serial number and role.

// Input schema
{
  deviceId:       string,                                          // required
  expectedSerial: string?,                                         // optional
  expectedRole:   "FOH" | "STAGEBOX" | "MONITOR" | "UNKNOWN"?    // optional
}

// Returns: JSON object
{
  valid: boolean,
  reasons: string[]    // empty when valid; describes mismatches when not valid
}

Fat Channel relevance: None — use for pre-flight safety checks before any channel operation.

MCP Resources (Read-Only)

Resources are read by URI. Fat Channel data appears in two resources.

#### presonus://mixer/{deviceId}/channels ← Primary Fat Channel resource

Returns all normalized channels for a connected mixer. This is the main resource for Fat Channel state.

URI pattern: presonus://mixer/StudioLive32SC-SD7E21010066/channels

Response schema — array of MixerChannel objects:

MixerChannel {
  id:      string,          // "line.ch1", "aux.ch3", "sub.ch1", etc.
  selector: {
    type:      "LINE" | "RETURN" | "FXRETURN" | "TALKBACK" | "AUX" | "FX" | "SUB" | "MAIN",
    channel:   number,      // 1-based channel number
    mixType?:  "AUX" | "FX",    // present for send-context channels
    mixNumber?: number
  },
  name?:   string,          // channel label from mixer (e.g. "Kick In")
  mute?:   boolean,
  solo?:   boolean,
  fader?: {
    db?:     number | null,   // dBFS level; null if unknown
    linear?: number | null,   // 0.0–1.0 linear value; null if unknown
    raw?:    unknown          // raw mixer value for diagnostics
  },
  pan?:    number,          // 0.0 = full left, 0.5 = center, 1.0 = full right
  linked?: boolean,         // true = stereo-linked with adjacent channel
  color?:  string,          // RGBA hex, e.g. "ffff0000" = red

  // ── Fat Channel fields ──────────────────────────────────────────────────
  compModelName?: string,   // e.g. "FET", "COMP_160", "BRIT_COMP", "UNKNOWN"
  eqModelName?:   string,   // e.g. "STANDARD", "ALPINE_EQ_550", "PASSIVE"

  rawExtra?: Record<string, unknown>   // unmapped raw fields
}

Key Fat Channel fields:

NOTE: compModelName and eqModelName are read-only decoded strings — they tell you which model is active. They do not expose the compressor or EQ parameter values (threshold, ratio, attack, etc.). For those, read from raw/state (see below).

#### presonus://mixer/{deviceId}/raw/state ← Diagnostic / parameter access

Full raw state dump. Use for reading actual compressor/EQ parameter values. Not intended for agent reasoning logic — always prefer the normalized channels resource for model identification.

URI pattern: presonus://mixer/StudioLive32SC-SD7E21010066/raw/state

Relevant raw key paths for Fat Channel:

line.chN.opt.compmodel         { value: float, strings: int }   ← compressor model selector
line.chN.opt.eqmodel           { value: float, strings: int }   ← EQ model selector
line.chN.opt.swapcompeq        0 | 1                            ← signal chain order

line.chN.comp.on               0 | 1                            ← compressor enabled
line.chN.comp.input            float (dB threshold)
line.chN.comp.output           float (dB makeup gain)
line.chN.comp.attack           float (seconds)
line.chN.comp.release          float (seconds)
line.chN.comp.ratio            float or int (model-dependent)
line.chN.comp.keyfilter        float (Hz)
line.chN.comp.keylisten        0 | 1

line.chN.eq.eqallon            0 | 1                            ← EQ enabled
line.chN.eq.eqgain1-4          float (dB)
line.chN.eq.eqfreq1-4          float (Hz)
line.chN.eq.eqq1-4             float (Q factor)
line.chN.eq.eqbandon1-4        0 | 1 (per-band enable)
line.chN.eq.eqbandop1-4        0 | 1 (bell/shelf type)

line.chN.gate.on               0 | 1
line.chN.gate.threshold        float (dB)
line.chN.gate.attack           float (seconds)
line.chN.gate.release          float (seconds)
line.chN.gate.range            float (dB)
line.chN.gate.expander         0 | 1 (gate vs. expander mode)

line.chN.limit.limiteron       0 | 1
line.chN.limit.threshold       float (dB)
line.chN.limit.release         float (seconds)

line.chN.filter.hpf            float (Hz cutoff frequency)

Replace N with the 1-based channel number (e.g. line.ch1.comp.input). For aux/sub channels substitute aux.chN, sub.chN, etc.

#### Other Resources (Fat Channel not directly relevant)

Accepted Properties per Model — Compressor

These are the schema-validated fields accepted by FatCompressorStateSchema in the domain model (used when the adapter decodes raw state into structured objects).

#### STANDARD, TUBE, FET — Base compressor schema

{
  model:       "STANDARD" | "TUBE" | "FET",   // required discriminator
  enabled?:    boolean,
  thresholdDb?: number,                        // dB threshold
  ratio?:      number,                         // compression ratio (e.g. 4.0 = 4:1)
  attackMs?:   number,                         // attack time in milliseconds
  releaseSec?: number,                         // release time in seconds
  makeupDb?:   number                          // makeup gain in dB
}

#### BRIT_COMP — Adds sidechain fields

{
  model:        "BRIT_COMP",                   // required
  enabled?:     boolean,
  thresholdDb?: number,
  ratio?:       number,
  attackMs?:    number,
  releaseSec?:  number,
  makeupDb?:    number,
  // Additional fields:
  keyFilterHz?: number,                        // sidechain high-pass frequency (Hz)
  keyEnabled?:  boolean,                       // sidechain filter active
  sidechain?:   string                         // sidechain source channel id
}

#### COMP_160 — Different parameter names (no manual attack/release)

{
  model:         "COMP_160",                   // required
  enabled?:      boolean,
  thresholdDb?:  number,
  // NOTE: no ratio/attackMs/releaseSec — program-dependent in hardware
  compression?:  number,                       // compression amount (equivalent to ratio)
  outputGainDb?: number,                       // output/makeup gain in dB
  keyListen?:    boolean,                      // monitor the sidechain signal
  keyFilterHz?:  number,                       // sidechain HP filter frequency
  sidechain?:    string                        // sidechain source channel id
}

#### Other compressor models → UNKNOWN passthrough

Models EVEREST_C100A, FC_670, RC_500_COMPRESSOR, TUBE_CB, VT_1_COMPRESSOR, and CLASSIC_COMPRESSOR are not yet fully schema-defined. When decoded from live state they return:

{
  model:      "UNKNOWN",
  rawModelId: string | number,           // the raw opt.compmodel.value float
  rawParams:  Record<string, unknown>    // all raw comp.* fields from state tree
}

Read parameter values directly from raw/state for these models until their schemas are added.

Accepted Properties per Model — EQ

#### STANDARD EQ — Full parametric schema

{
  model:          "STANDARD",              // required
  enabled?:       boolean,
  highGainDb?:    number,                  // high shelf gain (dB)
  highMidGainDb?: number,                  // high-mid peak gain (dB)
  lowMidGainDb?:  number,                  // low-mid peak gain (dB)
  lowGainDb?:     number                   // low shelf gain (dB)
}

NOTE: Frequency and Q values are not yet in the normalized schema — read them from line.chN.eq.eqfreq1-4 and line.chN.eq.eqq1-4 in raw/state.

#### Other EQ models → UNKNOWN passthrough

Models PASSIVE, VINTAGE, ALPINE_EQ_550, BAXANDALL_EQ, RC_500_EQ, SOLAR_69_EQ, TUBE_EQ, VINTAGE_3_BAND_EQ, VT_1_EQ are not yet fully schema-defined. When decoded they return:

{
  model:      "UNKNOWN",
  rawModelId: string | number,
  rawParams:  Record<string, unknown>,
  bands?:     Array<{
    frequencyHz?: number,
    gainDb?:      number,
    qFactor?:     number,
    enabled?:     boolean
  }>
}

Read EQ parameters from line.chN.eq.* in raw/state for these models.

Write Capability — Current Status

No write tools exist. Fat Channel model selection and parameter adjustment via MCP is not yet implemented.

This is intentional — ADR-005 (read-only-first policy) and REQ-NF-002 require that write tools only be added after a ProposedChangeSet + audit log + confirmation flow is implemented.

What exists in code: An empty if (config.writeEnabled) stub in tools.ts with a warning log. No set_fader, set_mute, set_fat_channel, or any other write tool is registered.

What would be needed to implement Fat Channel writes:

1. A set_fat_channel_model tool: { deviceId, channelId, compModel?, eqModel? } — sets opt.compmodel and/or opt.eqmodel via the featherbear client
2. A set_fat_channel_params tool for threshold/ratio/attack/release etc.
3. Full ProposedChangeSet + audit log + optional confirmation flow per ADR-005
4. Tests updating REQ-NF-002 coverage

Agent workflow for Fat Channel today:

1. discover_mixers → get deviceId
2. refresh_mixer_state({ deviceId }) → ensure state is fresh
3. Read presonus://mixer/{deviceId}/channels → check compModelName and eqModelName per channel
4. Read presonus://mixer/{deviceId}/raw/state → inspect parameter values
5. Advise the human operator what to change in UC Surface (cannot write autonomously)

GUID Reference (from classID_Mapping.md)

Compressors

{
  "STANDARD":           "{870D04F7-212E-4F9C-ADBB-39A97216433F}",
  "TUBE":               "{7F8A4262-D377-48E3-9D48-15D82C400A71}",
  "FET":                "{1F831EC1-B8AC-4EE9-AD53-54227AF53D58}",
  "BRIT_COMP":          "{FEF33155-7A9E-4F4E-B209-CFE86DDAFC8E}",
  "CLASSIC_COMPRESSOR": "{C38F9E1A-0127-4BB8-9377-40C545A50328}",
  "COMP_160":           "{F0BD22BB-5FE8-4279-8B05-D089B4D7B0BB}",
  "EVEREST_C100A":      "{23F9C088-08BE-4259-9DCE-38720AE5DE73}",
  "FC_670":             "{85DD5632-A536-49FF-894A-9329FC1124E4}",
  "RC_500_COMPRESSOR":  "{6A372968-AFA7-4A3F-805D-A09A4AE15777}",
  "TUBE_CB":            "{C3C32BBC-42E2-41A7-99B5-EA1D62F897B5}",
  "VT_1_COMPRESSOR":    "{AF35E448-40EC-4C5A-A05C-B40A5AC0A42F}"
}

EQs (line channels)

{
  "STANDARD":           "{A0A8A068-14F0-4B04-BB6F-AF8329D0E8EE}",
  "PASSIVE":            "{C0730CBB-5135-4558-9222-C40BDBA036ED}",
  "VINTAGE":            "{E1C5E024-C5CD-473C-B08A-6EC177812E01}",
  "ALPINE_EQ_550":      "{CBDD0DD3-C5EF-495A-B4C7-92EC5E8FE146}",
  "BAXANDALL_EQ":       "{B4D3497E-4B1C-4CFA-B859-A918C17CDA03}",
  "RC_500_EQ":          "{63ADDF9B-0EC7-430A-AEBE-62B4CB5FBBD6}",
  "SOLAR_69_EQ":        "{03819C3F-DC16-4B7B-B521-14B4042192F2}",
  "TUBE_EQ":            "{09B38119-3945-40D1-BA33-2FA19620DAB0}",
  "VINTAGE_3_BAND_EQ":  "{4635DE88-C3D2-4645-BC4D-8DFD116D6914}",
  "VT_1_EQ":            "{A0FAF452-D664-4BA2-90FC-6BD4AC469B29}"
}

Bus/Aux/Sub EQ only

{
  "BUS_EQ": "{4B92A91C-C6FB-4F0F-AE51-841378E4F9CF}"
}