Buzzing/static noise from Quad Cortex

Quad Cortex
1

I’ve already contacted support@neuraldsp but wanted to see if anyone on this forum has had any similar experiences or potential solutions to this issue

I’ve recently been experiencing a buzzing/static noise from my quad cortex unit when using an XLR cable out of an output, and directly into monitors or a mixing board. This noise is also present when using headphones or recording via USB into a DAW. This buzzing noise is more prevalent when using a guitar with single coils (ex. Stratocaster, P90 Pickups). Regardless, you can hear the noise even when my guitar is unplugged or when it’s plugged in whether I’m playing or not.

I’ve never had any previous issues with buzzing/static noise when using my QC at various venues, bars, and at home. For a majority of the time that I’ve owned a QC, I’ve had a completely clean signal with no noise issues unless I was using a particular gain-y amp. For whatever reason this has only become a recent problem that was less noticeable at first until the past few weeks. I’ve also attempted to use the unit’s adaptive gate at a low to medium amount and the buzzing does silence while I’m not playing, but it can be heard while I’m actively playing my guitar. It can technically go away completely when I turn the noise gate really high, but it significantly impacts the trails of the delays and reverb I’m using along with my overall tone.

I’ve read numerous forms and threads of other QC user’s experiencing similar problems and I have attempted these potential fixes that have been reported by other users:

  • Using a Cioks DC7 Power Supply/ Crux instead of the power cable that comes with the QC
  • Using a Morley Hum Exterminator (used to clean up dirty power and filter unwanted ground noise) which didn’t help
  • Using different XLR cables in the output and 1/4 inch cables in the input
  • Unplugging the XLR Cable(s) out of the outputs before turning on the unit and not plugging them back in until it’s fully turned on

*Other context: I’ve very recently moved to a different area but I’ve started to notice this issue starting to happen at a venue where I had previously lived. It has gotten more noisier/noticeable as of recently since I have moved into a new area. Both at home when directly plugging into monitors and at a venue’s sound board.

Currently a frustrating issue that likely is due to the unit itself, but could still possibly be a power noise issue. Love the QC and everything that Neural DSP does but this issue has been documented on multiple forums with no clear solution.

Please let me know if you guys have any ideas to resolve this issue based on my experiences. Thanks!

2

I faced the issue when connecting my guitar via cable to the wireless connector Boss WL-50, while the wireless transmitter was inserted into the WL-50 base station (charging the transmitter).

Setup is WL-50 to tuner pedal to QC.
WL-50 has an input jack for guitar cable.

I removed the wireless transmitter from the base station and all noise was gone.

3

Have you tried the ground lift on the actual QC itself?

4

Yes, I’ve been having it off but turning it on makes it worse

5

To clarify (if this bit of information helps), when turning on the ground lift on the output(s), the noise remains the same. When turning on the ground lift on the input channel (that I’m plugged into/actively using) the noise starts getting louder and a clicking noise is also heard. I’ve been having the ground lift off for the entirety of the time I’ve owned my QC. The noise is there even if the ground life is off.

6

I hope this is helpful (QC Owner and long time lurker)… The QC NEEDS to be grounded in some way;
Example… if I don’t plug the master outputs (or USB to computer) into something which is grounded (computer, FRFR Speakers, etc), I WILL get buzz and what I would call a “grounding hum” - my understanding is the QC was designed that way - not sure why, but it’s a design issue, and power supplies for the QC generally won’t solve this issue.
Try plugging the QC (via USB output) into a computer that is grounded, or alternatively, a speaker/PA/amp that is grounded: Turn on the QC FIRST, let it boot up fully, then turn on the speaker/PA/amp or computer. Headphones, by themselves, are not going to give the unit a path to earth. Reverse that order when powering down.
This might not be your issue, but it certainly solved my issues with hum.
Additionally, hum and hiss can be related to your “gain structure”. Make sure you are not overdriving inputs or outputs within your whole signal chain.
Hope this helps!
Michael Schoenfeld
www.michaelschoenfeld.com

7

If you’ve already done these things, sorry for being redundant. I was going crazy when I just plugged in headphones, not realizing that even if I’m not using speakers/amp/computer, plugging SOMETHING into a path to ground was essential.
Good luck and please let us know what Neural says. This is a wonderful resource - I love my QC.
Michael Schoenfeld
www.michaelschoenfeld.com

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