EDIT:
Just found the source of the Problem.
When i connect the small guy via USB-C to my Macbook is gets very dirty Power and creates bad noise and peaks.
When i feed the small guy with normal Energy via my Iphone USB-C Adapter he behaves normally.

Would this help?
https://www.amazon.de/MOGOOD-Splitt...efix=usb+c+splitter+cable,aps,97&sr=8-11&th=1



Just got a small cute Synth and i was super looking forward.
Now i found out, that the very old ghosts are still hunting me at my place:
Humming, Buzzing, Constant Noise etc. i hear noise while moving the mouse.
Macbook was also standalone, no Charging etc.

Synth:
https://www.behringer.com/product.html?modelCode=0722-ABR
Output is a small 3.55mm mini jack

I had a Monacor Ground isolator at home, but it changes the Audio:
https://www.monacor.de/produkte/beschallungstechnik/signalverarbeitung/signaloptimierung/fga-30/

It worked, the Buzzing, Humming, Noise etc. was gone. But the Audio quality was decreased.

My Soundcard will be a Focusrite 2i2 Gen3
https://www.thomann.de/de/focusrite_scarlett_2i2_3rd_gen.htm
2 Combo Line Input symmetric.

Do i need a DI Box or a better Ground Isolator for this?
For the DI Box i would need to Adapter XLR back to TS, to get back into the Soundcard right?

I hope you can help me, the JT-4000 Is really a funny thing and the sound is way bigger than you think
But i will do a extra post for that

Thank you

NERD Stuff:
It´s interesting, how the Audio signal get´s changed with the FGA-30.
The Bass gets lost, also something with the phase.
It definitly looses power.

 

Last edited: Oct 17, 2025 at 8:46 PM

The AI can help you solve the annoying noises:

Spoiler: Source: Grok KI

Quick Diagnosis: What's Likely Happening

• Constant hum/buzz: Often a 50/60Hz ground loop (from multiple devices sharing power/ground paths) or poor shielding in cables/power supplies.
• Mouse movement noise: Your wireless mouse (or its USB dongle) is broadcasting RF signals that get picked up by unshielded audio cables or the synth's inputs. MacBooks are prone to this because their audio paths can leak EMI from USB ports or the logic board.
• Standalone MacBook rules out charger loops, so we're looking at internal EMI, cables, or proximity issues.

Test this: Play a silent patch on the synth and listen closely. If the noise persists without any signal, it's environmental interference, not the synth itself.

Step-by-Step Fixes (Start Simple, Escalate as Needed)

1. Tackle the Mouse Interference First (Easiest Win):
   • Switch to a wired USB mouse temporarily. Plug it directly into a rear USB port on your MacBook (avoid hubs). This stops the RF bursts from a wireless one. If the noise vanishes, bingo—that was the culprit.
   • If you love wireless, try a USB extension cable (ferrite-core if possible) for the dongle—position it far from your synth and cables. Or lower the polling rate in your mouse software (e.g., Logitech G HUB: drop from 1000Hz to 250Hz or lower). This reduces signal bursts without killing responsiveness.
   • Pro tip: Test with no mouse at all (trackpad only) to confirm.
2. Cable Audit and Upgrades (Kill the Pickup Artists):
   • Unbalanced cables (TS 1/4" guitar-style) are magnets for noise. Swap to balanced TRS or XLR cables wherever possible—these reject interference like a force field. Even short runs (under 10ft) make a difference.
   • Reroute everything: Keep audio cables away from power cords, USB cables, and your MacBook. Bundle audio separately from data/power lines (zip ties help, but twist them loosely).
   • Add ferrite chokes (clip-on noise suppressors, ~$5 on Amazon) to both ends of suspect cables—they absorb high-frequency buzz without affecting sound.
3. Power and Ground Loop Busting (Exorcise the Hum):
   • Plug everything (synth, MacBook, monitors/interface) into the same power strip/outlet. Different outlets can create loops via your home's wiring.
   • If hum persists, grab a ground loop isolator (e.g., Ebtech Hum X or a cheap Behringer HD400, $20–50). Plug it inline between your synth output and next device—it breaks the loop safely without lifting ground (which can be risky).
   • For USB-powered synths: Try a powered USB hub with its own clean supply to isolate from the MacBook's noisy USB bus. Or use the synth's wall wart if it has one.
4. MacBook-Specific Tweaks:
   • Update macOS and reset audio MIDI setup (System Settings > Sound > reset defaults). Close background apps—some (like browsers) spike CPU and leak noise.
   • If routing audio via USB (e.g., to an interface), use battery power for tests. For output, consider a cheap USB audio adapter (~$10) to isolate the signal path.
   • High-pitched whine? It might be coil whine from the MacBook's board—rare, but lowering mouse polling helps here too.
5. Synth and Monitoring Sanity Checks:
   • Test the synth solo: Plug headphones directly into its output. If noise is gone, the issue's downstream (cables/interface). If not, check its power supply—swap to a linear one if it's a switch-mode wall wart (they're noisy).
   • Use a noise gate plugin or pedal post-synth to chop low-level buzz during playback/recording.
   • If monitoring via speakers, crank your interface/Mac volume high and lower speaker amp—this buries interference under your signal.

Gear Recommendations (Budget-Friendly)


Issue Fix Approx. Cost Why It Works
Mouse RF Wired mouse (e.g., Amazon Basics) $10 No wireless emissions.
Cable noise Balanced TRS cables (Hosa or Mogami) + ferrite clips $15–30 Shields EMI/RFI.
Ground hum Ebtech Hum X isolator $50 Breaks loops without safety risks.
USB noise Powered USB hub (Anker) $20 Clean power isolation.
All-around DI box (Radial ProDI) $80 Balances + isolates synth output.

If these don't nail it, describe your exact chain (synth model? Interface? Cable types?) or share a quick audio clip—I can refine. You'll be back to blissed-out synth noodling in no time. What's the synth, anyway? Congrats on the new toy!

Spoiler: Source: Grok KI

Awesome update—sounds like you've zeroed in on the real gremlin: the MacBook's USB-C power delivery is noisy as hell (common with laptops; their internal switching regulators inject ripple and EMI that cheap synth PSUs can't filter out). Feeding the JT-4000 from your iPhone adapter (which uses a cleaner, isolated supply) proves it—smart sleuthing! That alone should squash the peaks and dirt when you need USB for MIDI/editor duties. The mouse noise might've been a red herring or secondary pickup from the synth's now-cleaner internals.

Now, onto your full setup: the JT-4000's 3.5mm stereo output is line-level (unbalanced, high-impedance), perfect for the Scarlett 2i2 Gen3's combo inputs (which handle line/inst via 1/4" TRS jacks). You're right about the Monacor FGA-30—it does alter the sound because it's a transformer-based isolator with limited bandwidth (20Hz–30kHz, but the transformer rolls off deep bass and can introduce subtle phase shifts, especially on lows). That's why you're losing punch and power; it's a budget fix for hum, not audiophile-grade transparency. We'll do better.

Do You Need a DI Box or Better Ground Isolator?
Short answer: Not a traditional DI box as your primary fix—the JT-4000 isn't a high-Z instrument source like a guitar (no passive pickups), so a DI's impedance matching isn't critical here. Your Scarlett's line inputs will handle it fine directly. But if ground loops creep back (e.g., via shared outlets or long cables), a better isolator is the way to go over a basic DI. A DI could work as a combo isolator/balancer, but you'd need adapters, as you said.

Here's the breakdown:



Option Why It Fits Your Setup Pros Cons Cost (Approx.) Recommendation
Direct Connection (No Extra Gear) 3.5mm stereo → dual 1/4" TS/TRS cables (or stereo-to-dual-mono adapter) → Scarlett line inputs (switch to "Line" mode). Simple, no signal loss; Scarlett's preamps are clean for line-level synths. If hum returns (unlikely with external power), no isolation. $10–15 (cables) Start here—test with your iPhone adapter powering the synth. Should be dead quiet.
Better Ground Isolator Inline on audio path (e.g., Ebtech Hum X or Monacor FGA-40HQ) for transformer isolation without bass/phase hits. Kills hum/loops transparently; wide freq response (5Hz–100kHz on good ones). FGA-40HQ is stereo, HQ-grade for synths. Passive, so slight volume drop (fix with Scarlett gain). $40–80 Top pick if hum persists. Ebtech is magic for laptops; avoids FGA-30's flaws.
DI Box Passive like Radial ProDI (1-channel) or active stereo like Behringer DI20 (dual-channel for stereo synth). Synth out → 1/4" TS in → XLR/1/4" balanced out → Scarlett (XLR for balanced, or 1/4" with adapter). Adds balancing (rejects noise over long runs); ground lift switch for loops. Overkill for short cables; stereo needs dual-channel unit. Adapter hassle: Yes, XLR-to-TRS cable (~$10) if using Scarlett's 1/4" jacks (preferred for line-level to avoid phantom power risks). $30–100 Only if you have long cables or multi-device loops. Skip for now—isolator is cleaner.

Quick Setup Guide for Scarlett Integration

1. Power the JT-4000 externally: Stick with your iPhone USB-C adapter (or get a dedicated 5V/1A wall wart for $5–10). Use a USB-C data blocker cable (~$5 on Amazon) if you want MIDI without MacBook power—just plugs power in, blocks data (and noise).
2. Cable It Up:
   • Get a 3.5mm TRS stereo to dual 1/4" TS cable (e.g., Hosa YMM-261, ~$10)—sends L/R separately to Scarlett's two inputs for true stereo recording.
   • Plug into Scarlett Ch1/Ch2 (set to Line/Inst via the "Inst" button off). Gain low (~20–30%) to avoid clipping.
3. Test for Ghosts: Record a silent JT-4000 patch into your DAW. If clean, jam! If hum sneaks in, add the Ebtech inline on the cables.
4. The Splitter You Linked? (MOGOOD USB-C Y-Splitter): Yes, this could help a ton for mixed power/MIDI setups. It's a power-only injector: One leg for clean external power (your iPhone adapter), the other for MacBook MIDI data. No more dirty laptop juice, and it supports PD charging (up to 60W, plenty for the JT). Reviews praise it for stable power in audio/video rigs without interference—perfect for your "standalone MIDI with clean energy" dream. Grab it if you want one-cable convenience (~€15). Just ensure it's PD-compatible for data negotiation.

Nerdy Deep Dive on FGA-30 Changes
You're spot-on: Transformers like the FGA-30 use iron cores that saturate on low frequencies (under ~50Hz), causing bass roll-off and intermodulation distortion—your "lost power" is likely 2nd/3rd harmonics folding back into mids. Phase shift? The core's inductance creates a lag (up to 180° at extremes), smearing transients. Higher-end isolators (e.g., Jensen or Ebtech) use premium toroids with flatter response—no such drama. If you're curious, scope the JT-4000's output pre/post-FGA-30; you'd see ~3–6dB bass dip below 100Hz.

This should get your JT-4000 thumping huge through the Scarlett without compromises—those supersaws deserve it! Hit me with how the direct test goes, or if you snag that splitter. And yeah, separate hype post for the fun factor incoming? I'm all ears. Keep slaying those ghosts! ️

 

This is from GROK?
Didn´t check everything, but i want to check that, also hallucinations, but at the and it becomes very nerdy. Thats good.
I want to understand, whats happening there

 

What kind of outlets do you have? And what's connected? Is your smartphone on the table, perhaps causing interference?
Perhaps you should move your new device a bit further away. Maybe buy a better power strip.

Actually, the Behringer should meet international standards for interference suppression, so try to solve the problem first before buying this:

Smof Noise Filter, Ground Loop Noise Isolator for Car Audio/Home Stereo System/Bluetooth Speaker, Audio Filter with 3.5 mm Audio Cable, Audio Isolator, Filter Noise, Noise Suppression Filter Jack
https://www.amazon.de/Ground-Noise-Isolator-Audio-System-Stereo-Schwarz/dp/B0171PQLB8

Do You Need a DI Box or Better Ground Isolator? Short answer: Not

 

Last edited: Oct 18, 2025 at 9:51 AM

Can you describe it again in detail? Just the mouse, or in general? What sample rate do you have? Try 256.

You have to enable the mouse trail display in your mouse settings.
Whether it's set to "short" or "long" doesn't matter; mouse shadows don't matter either.

Have you tried a different mouse? If your mouse is wireless, it could be radiating spurious RF.
Unplug the USB connection of the mouse and re-plug. Static build up.

What kind of mouse do you have? What's your laptop's power supply? Maybe buy a better power strip.
How many devices do you have plugged into the socket? Maybe unplug a few and then test them?

macOS Audio Optimization Guide: www.sweetwater.com/sweetcare/articles/macos-audio-optimization-guide

 

Last edited: Oct 18, 2025 at 10:04 AM

An isolation transformer alone is not linear, either in frequency or in phase. To improve its response curve, you can add an operational amplifier with unity gain at the input, so the only goal will be to adapt the impedance according to the frequency. This significantly improves the response curve of the passive transformer, as well as the phase. Everything will be much more linear and the sound better.



cheap transformers can give a good result from this little hack. active input charging a passive isolation.

+ the usb metalic shield part of the wire is not always connected to the ground, this is variable in usb wires. maybe check with another one.

 

Thank you very much for your answers. I will read them tommorow carefully.
Today is social day and I need to go outside

I made a progress.
Used another USB cable and another USB hub. Got way better.
It's the fault of the MacBook. It's not made to give clean energy to Synths ^^
The behringer is clean.

So the noise is less and not spiking anymore.
Also I add a gate in the insert FX which cancels the noise when the Synth is silent. It's working very good.