Active DI Schematic Capture

flux

Reviewed the schematic block-by-block and fixed what was actionable: replaced the rail test-point placeholders with Keystone 1040 parts, added missing/provisional MPN metadata, corrected several generic passive package choices, classified key nets, and re-ran checks clean. I updated Schematic Capture Notes with the review findings and remaining placeholders.
Open items:
  • Exact Flux parts are still needed for THAT1646W16-U, Hammond 1140-DB-A, FFSAS02BFR, RACM30-15DK/277/OF, and some mechanical connectors/switches.
  • Direct schematic symbol rearrangement was not available through the exposed tools; I documented this and avoided making PCB layout changes.
Suggested next steps:
  1. Manually tidy schematic symbol positions in the editor, or rerun when a schematic-arrange tool is available.
  2. Create/import exact custom parts for the remaining placeholders.
  3. Move to mechanical/package verification before PCB layout.
jakey0101

jakey0101

Can you delete the components specifically part of the GLB network?

flux

I’ll find the components tied specifically to the GLB option, remove only those, then verify the A0/chassis domains remain otherwise intact.

flux

Removed the GLB-specific component JP_GLB from the schematic. I verified the checked ERC/DRC categories are still clean, and updated Schematic Capture Notes to record the GLB removal.
Open items:
  • A0 and CHASSIS remain separate elsewhere; connector shield/chassis terminations were not changed.
  • No other GLB-specific schematic components were found.
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Schematic

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Schematic Capture Notes
Capture Status
  • Initial Active DI schematic capture started in Flux from the supplied schematic-ready design spec and architecture reconciliation.
  • Main functional blocks are represented and wired: input/thru, selectable input load, OPA1656 buffer, switched OPA1612 HPF, master level, OPA1612 driver, transformer XLR output, optional THAT1646 TRS branch, and ±15 V PSU/chassis topology.
  • ERC/DRC check subset for floating pins, power pins, single-pin nets, no-connects, missing footprints, wire collisions, label collisions, and chain coherence currently reports no open error/warning checks.
Exact Library Parts Used

Table

DesignatorCaptured PartIntended Identity
U1OPA1656IDTI OPA1656ID SOIC-8
U2OPA1612AIDTI OPA1612AID SOIC-8
J_IN / J_THRUNMJ4HCD2Neutrik NMJ4HCD2
D_IN_CLAMPBAV199LT1GBAV199 low-leakage clamp option
D_LINE_*1N4004-TP1N4004-E3/54 class DO-41 clamp diodes
Schematic-Level Substitutes / Placeholders

Table

DesignatorFlux Part UsedIntended Part / Note
U3ISO1432DW wide SOIC-16 placeholderTHAT1646W16-U was not found in the library; pin-number mapping was used as a placeholder only. Replace with exact THAT1646W16-U SO16W before PCB release.
T_XFMRTY-250P audio transformer placeholderHammond 1140-DB-A was not found in the library; lead/phase/shield mapping still requires physical validation.
J_XLRNC3MAHSchematic substitute for Neutrik NC3MD-LX-B.
J_TRSSJ3-350144A-TR-X7Schematic substitute for Neutrik NJ3FP6C-BAG; not footprint-compatible with 1/4 in isolated TRS.
SW_ZMRX108-ASchematic substitute for Grayhill 56A30-01-1-04N 1P4T input-load selector.
SW_HPFR20307RN02QSchematic substitute for Grayhill 56D30-01-2-AJN 2P3T HPF selector.
SW_POL7201MD9ABEDPDT schematic substitute for E-Switch 100DP1T1B1M1QE polarity switch.
PSU1RAC10-15DK/277Functional placeholder for RECOM RACM30-15DK/277/OF.
J_MAINSDB126V-5.0-3P-GNPlaceholder for XP Power FFSAS02BFR filtered IEC/switch/fuse module.
RV_LEVELRK27112A00CCSimilar RK27 dual pot placeholder for RK27112A00CF.
FB_TRS_TIP / FB_TRS_RINGFCM2012HF-202T02Ferrite placeholders; exact matched ferrites still NEEDS_REVIEW.
Important Net Mapping
  • J_IN_TIP: input tip hardwired to thru tip and R_IN_SER input.
  • IN_PROTECTED: post-1 kΩ input/protection node, input load high side, OPA1656 input, RF cap, and BAV199 clamp midpoint.
  • BUF_OUT: OPA1656A unity output and HPF switch input.
  • HPF_N1, HPF_N2, HPF_OUT: Sallen-Key HPF nodes and OPA1612A output.
  • LEVEL_TOP, LEVEL_WIPER, DRV_IN, DRV_OUT: master level and OPA1612B driver nodes.
  • XFMR_SRC, XFMR_DRIVE, XLR_SEC_A, XLR_SEC_B, XLR_2, XLR_3: transformer branch nodes.
  • LINE_OUT_P, LINE_OUT_N, TRS_TIP, TRS_RING: optional THAT1646/TRS branch nodes.
  • +15V_RAW, -15V_RAW, A0_PSU, +15V_A, -15V_A, A0, CHASSIS: supply, analog return, and chassis domains.
Open Items Before Production PCB/Layout
  • Replace placeholder parts with exact library/custom components where needed, especially THAT1646W16-U, Hammond 1140-DB-A, Grayhill switches, FFSAS02BFR, RACM30-15DK/277/OF, NJ3FP6C-BAG, and NC3MD-LX-B.
  • Confirm exact pin/lead mapping for Hammond 1140-DB-A by continuity and phase tests.
  • Confirm U3 placeholder pin-number mapping against THAT1646W16-U datasheet before any layout.
  • Choose exact THAT1646 common-mode capacitors and matched ferrites.
  • Decide fitted transformer source resistor option from measurements.
  • Review footprint/package choices for all generic passives before PCB layout or manufacturing.
  • Perform schematic readability cleanup/placement before moving to PCB layout.
2026-07-21 Block Review and Cleanup Pass
Block-by-block review result
  • Input / thru / loading: Connectivity matches the intended hardwired passive thru, 1 kΩ series protection, permanent 10 MΩ reference, and switched low-side shunts. Input jack NC contacts and unused switch throws are marked no-connect.
  • OPA1656 buffer: Channel A is wired as a unity follower from IN_PROTECTED to BUF_OUT; channel B is parked as a unity follower referenced to A0. ±15 V pins have local 100 nF and 10 µF bypassing.
  • Switched HPF: The two-pole, three-bank HPF network is captured with 3.3 µF / 1.6 µF / 0.82 µF pairs, 10 MΩ bleeds, 1.65 kΩ feedback, 3.32 kΩ bias, and OPA1612A unity feedback.
  • Master / driver: HPF_OUT is AC-coupled into the paralleled RK27 placeholder, wipers are paralleled through the 1 kΩ stopper into OPA1612B, and the 1 MΩ fail-safe returns DRV_IN to A0.
  • Transformer XLR branch: OPA1612B drives the mutually exclusive source options, 3.3 µF block, transformer placeholder, DPDT polarity switch, and XLR connector with pin 1/chassis kept separate from the floating secondary.
  • Optional THAT/TRS branch: The placeholder U3 remains a wide-SOIC-16 footprint stand-in only; output clamps, sense capacitors, ferrites, RFI caps, and TRS connector are wired and DNP/NEEDS_REVIEW status is preserved where applicable.
  • Power / chassis: Mains/PSU placeholders, ±15 V raw and analog rails, rail-entry bulk, local bypassing, rail test points, A0/A0_PSU star, and GLB-to-chassis option are captured. Net type metadata now classifies rails, grounds, chassis, mains, and analog signals.
Placeholder/metadata fixes made
  • Replaced generic rail test points with exact Keystone 1040 components and restored TP_P15, TP_A0, and TP_N15 net connections.
  • Added provisional Samsung CL10B104KB8NNNC metadata for the four compact 100 nF op-amp rail decouplers.
  • Added candidate/source metadata for R_XFMR_6K8 (MRS16000C6801FCT00, still allocation/purchase NEEDS_REVIEW) and R_XFMR_0 (0 Ω jumper/wire-link implementation still NEEDS_REVIEW).
  • Updated package metadata for 1206 input/bleed resistors, axial held resistors, local radial 10 µF capacitors, input RF ceramic, and rail-entry hybrid/polymer capacitors.
  • Submitted missing-part requests for THAT1646W16-U, Hammond 1140-DB-A, XP Power FFSAS02BFR, and RECOM RACM30-15DK/277/OF because exact Flux library components were not available.
Readability / placement status
  • Current schematic ERC/readability lint is clean for the checked categories, but direct visual symbol placement/rearrangement was not available through the exposed schematic-edit tools in this session. A PCB/layout-position tool was tested and immediately reverted because it targets PCB component placement rather than schematic symbol placement.
  • Manual schematic visual cleanup remains recommended in the editor, or should be repeated when a direct schematic placement/arrange mutation is available.
Check status after cleanup
  • Checked categories report no open ERROR/WARNING/UNCERTAIN items: floating pins, power pins, missing footprints, manufacturer part numbers, wire collisions, label collisions, chain coherence, and component-outside-board.
2026-07-22 GLB Removal
  • Removed JP_GLB, the schematic's GLB-specific A0-to-CHASSIS option component.
  • A0 and CHASSIS remain separate nets elsewhere in the schematic; existing chassis terminations such as connector shields/XLR pin 1 were not changed.

  • Capture Status

  • Exact Library Parts Used

  • Schematic-Level Substitutes / Placeholders

  • Important Net Mapping

  • Open Items Before Production PCB/Layout

  • 2026-07-21 Block Review and Cleanup Pass

  • Block-by-block review result

  • Placeholder/metadata fixes made

  • Readability / placement status

  • Check status after cleanup

  • 2026-07-22 GLB Removal