# MIDI Latency Issue with Scaler 2 & Scaler 3 as MIDI FX in Logic Pro 11 /12 (Specific to Apple Studio Instruments)

**URL:** <https://forum.scalermusic.com/t/midi-latency-issue-with-scaler-2-scaler-3-as-midi-fx-in-logic-pro-11-12-specific-to-apple-studio-instruments/24439>\
**Category:** Bug Reports\
**Created:** [February 27, 2026, 1:32am UTC](https://forum.scalermusic.com/t/midi-latency-issue-with-scaler-2-scaler-3-as-midi-fx-in-logic-pro-11-12-specific-to-apple-studio-instruments/24439 "2026-02-27T01:32:40Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![HERODEM](https://avatars.discourse-cdn.com/v4/letter/h/b5a626/32.png) [@HERODEM](https://forum.scalermusic.com/u/HERODEM)\
**Post date:** [February 27, 2026, 1:32am UTC](https://forum.scalermusic.com/t/midi-latency-issue-with-scaler-2-scaler-3-as-midi-fx-in-logic-pro-11-12-specific-to-apple-studio-instruments/24439/1 "2026-02-27T01:32:40Z")

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I am writing to report a persistent MIDI latency issue I am experiencing with both **Scaler 2** and **Scaler 3** while using them as **MIDI FX** plugins in **Logic Pro**.

**The Issue:** When Scaler (2 or 3) is placed in the MIDI FX slot to c

 ![Sin título](https://canada1.discourse-cdn.com/flex012/uploads/scalermusic/original/2X/c/c627703a7857831c8dcc71e56fa3038201ec9727.jpeg)

ontrol Apple’s “Studio” series instruments (such as _Studio Horns_ or _Studio Cellos_), there is a significant delay/lag between the key press and the actual sound output. This issue does **not** occur when using simple stock instruments like the “Classic Electric Piano”.

**Troubleshooting already performed:**

1. **Scaler Settings:** I have disabled _DAW Sync_, _Play Quantize_, and set _Input Quantize_ to OFF. I also ensured _Bind MIDI_ is not forcing a “Next Beat” trigger.

2. **Logic Pro Settings:** I am using a low I/O Buffer Size and have “Low Latency Monitoring Mode” active. I have also tested different Latency Compensation settings.

3. **Instrument specific:** I have disabled “Legato Transitions” and “Auto Voice Split” within the Studio Instruments to rule out internal script processing lag.

**Observation:** The lag is only present when Scaler is used in the **MIDI FX slot**. If I load Scaler as a **Software Instrument** and route the MIDI, it works perfectly. This suggests a synchronization conflict between the MIDI FX engine and the high-buffer requirements of Apple’s multi-sampled Studio instruments.

**System Specs:**

- **DAW:** Logic Pro (Latest version)

- **Plugins:** Scaler 2 & Scaler 3 (AU MIDI FX)

- **OS:** macOS [Tu versión aquí]

Could you please advise if there is a workaround or a fix planned for this specific MIDI FX behavior?

Best regards, julian

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**Author:** ![davide](https://yyz2.discourse-cdn.com/flex012/user_avatar/forum.scalermusic.com/davide/32/824_2.png) [@davide](https://forum.scalermusic.com/u/davide)\
**Post date:** [February 27, 2026, 7:23pm UTC](https://forum.scalermusic.com/t/midi-latency-issue-with-scaler-2-scaler-3-as-midi-fx-in-logic-pro-11-12-specific-to-apple-studio-instruments/24439/2 "2026-02-27T19:23:31Z")

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Hi @Julian I have the same setup and just checked and get 0 delay. Have you tried another third party or even Logic MIDI FX as a process of elimination?