Quad Cortex Mini

[mbenigni]

Yeah, it's the super annoying part about the re-anti-hype machine that has surrounded the QC. I have no idea if the "noise issues" were power supply related or inherent to the device, at this point no idea if they were real or imagined, blah blah blah blah.

Any discussion concerning noise levels is fraught because there are different kinds of noise. (Also true when discussing “squirrels”.) And each of these has its own potential causes.

It’s reasonable to consider relative noise floor with high gain presets - what I’d call “hiss” - but this concern has been at least somewhat overstated IMO. I’m skeptical of this being directly related to the PSU either way. (And most modelers, including the QC, are so quiet in this regard compared with IRL tube amps at similar gain, I suspect they’re all playing games with noise reduction even in absence of dedicated gate/NR blocks.)

As for ground loops/ “buzz”, any device with 2 prong power can exhibit these issues depending on configuration and environmental variables.

Briefly pretending that the PSU was to blame and that a replacement would magically cure it was a classic case of NDSP telling everyone what they wanted to hear, IOW a fuck up. (Totally fair to hold their feet to the fire on this account.) I think they went dark on this subject because they realized it was neither a solution nor the problem in the first place.

 

[mbenigni]

For those that have both, is the screen the same on both? It looks better on the QC mini in all the promo shots but I’m assuming they’re actually pretty similar?

I’m guessing it’s the very same part, but it looks different because of the contrast with the black bezel, etc. Curious myself, though.

 

[mbenigni]

@mbenigni Just looking at that power adapter made me punch my tv screen.

That PSU looks different than the OG “Golden Profits” we all know and love. Not sure whether it’s the same part with their new logo sprayed on, or whether it’s “improved” in some other way (e.g. now with more TGF placebo LOL.)

 

[R590]

For those that have both, is the screen the same on both? It looks better on the QC mini in all the promo shots but I’m assuming they’re actually pretty similar?

They are indeed similar, but the mini has a thicker glossy layer over it that is a bit convex at the edges. The original is dead flat all the way to the edges, slightly recessed, and not as glossy to my eye.

It seems to be the same panel on both, but it is under a larger layer of “glass” on the mini. That layer extends to the device edges giving you a bit of bezel.

Edit: On closer inspection, my QC screen is probably just showing a bit of age in the glossiness department. This is from the original run years ago.

 

[mbenigni]

…but eventually that headphone noise issue went away without it.

When everyone remembered that their QC was actually more useful connected to monitors or a power amp or anything else (and the three people on the planet who longed to play their QCs in a hotel room with nothing but headphones moved on to WAZA Airs instead. )

The old, “Doc, it hurts when do this.”

 

[Chocol8]

The timbuck3 strategy.

He said QC2 not QC22

 

[mbenigni]

He said QC2 not QC22

Tomorrow, tomorrow.
I love you, tomorrow.
You’re always a day away.

 

[Jarick]

My QC was a little more susceptible to noise than other modelers but just by a small bit. I have a non isolated AB switch pedal that I would run into both the QC and Axe 3 and be able to instantly switch. There was a tiny bit of signal noise that would intermittently jump into both units for some reason and it was louder on the QC than on the Fractal. At first I thought it was a noise issue on the QC but then realized it was on the Fractal too, just quieter.

I have two issues with the QC power supply. One is that the cable is extremely thin and flimsy, like there's barely any insulation or protection on it. The HX Stomp PS cable feels like a tank in comparison. That's terrible for a $1700 device to come with such a cheap power supply. The other is just how easy it was to accidentally unplug it. Mini looks to have fixed both of those with the new power supply which has a proper amount of insulation and a twist lock (like my UAD Apollo has).

It is a really sweet looking unit that would be fun to have on a desk. Also looks like a great size for a mini board. For me the price is too high to grab as a fun side piece which is more in the HX Stomp land.

 

[deadpool_25]

@deadpool_25 Can you compare the noise floor of each unit in front of an amplifier - specifically high gain? As if you were going to use it for effects only ?

Sure. I can put them in front of my Badlander 25 on the crunch an crush channels. Does signal chain matter? Or just comparing the noise with guitar straight in vs through the two QC’s with no effects in the chain…just a blank input 1 to multi out path?

 

[deadpool_25]

Ok, these are for @Orvillain

Constants: straight into the front into the Badlander 25 on Crunch mode with gain at max, EQ at noon, and master at 10:00 (think God I’m not actually playing through it beccause it would be incredibly loud). Theres nothing in the loop. The cab is a custom oversized 2x12 with V30s. Amp is plugged into a Furman power strip. The QCM and QCM output levels are both at 0db (which, upon later checking, makes no difference in the noise).

1. Nothing at all plugged into the amp input. There’s some hiss as you’d expect since the gain is cranked. It increases pretty significantly if I put it on Crush mode. I put it back to Crush and moved on.

2. I plugged a cable from my Epiphone Adam Jones LP into the front of the amp. With the volume rolled down on the guitar there’s no change in the hiss.

3. I plugged both QC’s into the same wall outlet (not the one with the power strip). I brought up a blank preset with the top path going input 1 to output 1 (mono). I ran an XLR to TS cable from output 1 of the QC to the front of the amp. The hiss increased significantly. I did the same with the QCM and while there is a change is much, much less. This is a HUGE difference. The hiss with the QCM increased a little and it introduced what I think is a little ground hum. This is not an insignificant amount of noise but I suspect it would be similar with about any outboard gear. I’ll try the VP4 in a bit. Again I’m using stock power supplies here which are two-prong.

4. The difference was so big that I swapped XLR-TS cables to see if one was wonky. No difference. It’s not the cable.

5. Checking the power supply. I shut down both units and unplugged the QCM adapter from the wall. I’m only going to use the QC adapter this time. I used the adapter that comes with the QCM to power the QCM with the QC power supply and turned the QCM back on. Again the noise did increase and I think I’m still getting a little ground hum but I think it’s the same amount of increase I got with the QCM’s power supply, though it might be a tiny bit louder now.

6. Now I’ll go back to using their stock power supplies but into the Furman power strip the amp is plugged into. Same huge difference. I’m starting to see why Orvie said the QC was unusable. If he’s using it in this manner…yeah, fuck that.

7. Okay let’s try this using a Ciocks Crux being run off a DC7 that is grounded. The DC7 is plugged into the same Furman as the amp. No different with the QC. It’s a noisy bitch! The QCM still increases the hiss a little but again this seems quite usable.

(This is where I noticed an issue with the testing but I’ll come back to it.)

8. Let’s try the VP4 vs the QCM. The VP4 doesn’t have an XLR out so I used a Mogami silver instrument cable. The QCM seemed a little quieter than the VP4 in this case. I swapped the QCM path to use output 3 instead so I could use the same Mogami cable for both. I think they sound about the same in terms of noise. An increase but a normal one I think.

9. About the problem I noticed. The QCM’s volume was at 100% the whole time. The QC’s is at a tiiiiny bit below 9:00. Holy shit, if this thing gets even noisier…

9. So it turns out the QC was on 14%. It’s fine though as cranking the volume up to 100% didn’t change the noise so I’d say that was a non-issue after all.

My conclusion: using the QC into the front of a high gain tube amp can be noisy AF. The QCM is much, much better and is on par with the VP4.

 

[Mongillo19]

My conclusion: using the QC into the front of a high gain tube amp can be noisy AF. The QCM is much, much better and is on par with the VP4.

Do you have post board change QC or an older one? I wonder if that changes anything

 

[deadpool_25]

Addendum to testing above:

I decided to see if this huge noise difference also existed through my EV PXMs. It does and doesn’t. The QC is noisier than the QCM but I can barely hear it either way. I need to crank the EV’s volume and have my ear up near the speaker to hear the noise. So I think it’s a non factor in tha setup (through an FRFR type system) so perhaps that’s why not many people complain about noise issues.

Hm. I should probably check the difference, if any, through the amp’s FX loop. Duh.

The noise difference is still evident through the amp’s FX loop, but similarly to the EV’s I don’t think it’s an issue. I had to turn the amp’s master volume up to noon to make it obvious (ch 1 master controls it in a straight into the loop scenario). That would be super loud.

So to add to the conclusion above, if you’re running into the front of your high gain amp you just don’t want to be using the QC. Not sure about 4CM but I’d expect similar results.*

With the QCM you’d be just fine running into the front. So…

Welcome to the team, @Orvillain

* Fucking hell. Gimme a few minutes.

 

[deadpool_25]

Do you have post board change QC or an older one? I wonder if that changes anything

How can I tell?

 

[Lysander]

How can I tell?

Some options in the I/O settings page change, as the new ESS codec doesn't have feature parity with the old one.

https://neuraldsp.com/quad-cortex-updates/quad-cortex-development-update-56

 

[Mongillo19]

Some options in the I/O settings page change, as the new ESS codec doesn't have feature parity with the old one.

View attachment 58399

https://neuraldsp.com/quad-cortex-updates/quad-cortex-development-update-56

And to add to that it would have been a post August 2025 QC which you've had yours awhile. So I'm going to assume it isn't a new board

 

[Los-D]

using the QC into the front of a high gain tube amp can be noisy AF

My experience as well (among other instances of noise with QC compared to multiple modelers).

The QCM is much, much better and is on par with the VP4.

This is good news for sure. Good to hear

 

[deadpool_25]

Okay mine does display the Type in the I/O section and yeah I’ve had it for what…a year? So it’s the old board.

 

[Orvillain]

Ok, these are for @Orvillain

Constants: straight into the front into the Badlander 25 on Crunch mode with gain at max, EQ at noon, and master at 10:00 (think God I’m not actually playing through it beccause it would be incredibly loud). Theres nothing in the loop. The cab is a custom oversized 2x12 with V30s. Amp is plugged into a Furman power strip. The QCM and QCM output levels are both at 0db (which, upon later checking, makes no difference in the noise).

1. Nothing at all plugged into the amp input. There’s some hiss as you’d expect since the gain is cranked. It increases pretty significantly if I put it on Crush mode. I put it back to Crush and moved on.

2. I plugged a cable from my Epiphone Adam Jones LP into the front of the amp. With the volume rolled down on the guitar there’s no change in the hiss.

3. I plugged both QC’s into the same wall outlet (not the one with the power strip). I brought up a blank preset with the top path going input 1 to output 1 (mono). I ran an XLR to TS cable from output 1 of the QC to the front of the amp. The hiss increased significantly. I did the same with the QCM and while there is a change is much, much less. This is a HUGE difference. The hiss with the QCM increased a little and it introduced what I think is a little ground hum. This is not an insignificant amount of noise but I suspect it would be similar with about any outboard gear. I’ll try the VP4 in a bit. Again I’m using stock power supplies here which are two-prong.

4. The difference was so big that I swapped XLR-TS cables to see if one was wonky. No difference. It’s not the cable.

5. Checking the power supply. I shut down both units and unplugged the QCM adapter from the wall. I’m only going to use the QC adapter this time. I used the adapter that comes with the QCM to power the QCM with the QC power supply and turned the QCM back on. Again the noise did increase and I think I’m still getting a little ground hum but I think it’s the same amount of increase I got with the QCM’s power supply, though it might be a tiny bit louder now.

6. Now I’ll go back to using their stock power supplies but into the Furman power strip the amp is plugged into. Same huge difference. I’m starting to see why Orvie said the QC was unusable. If he’s using it in this manner…yeah, fuck that.

7. Okay let’s try this using a Ciocks Crux being run off a DC7 that is grounded. The DC7 is plugged into the same Furman as the amp. No different with the QC. It’s a noisy bitch! The QCM still increases the hiss a little but again this seems quite usable.

(This is where I noticed an issue with the testing but I’ll come back to it.)

8. Let’s try the VP4 vs the QCM. The VP4 doesn’t have an XLR out so I used a Mogami silver instrument cable. The QCM seemed a little quieter than the VP4 in this case. I swapped the QCM path to use output 3 instead so I could use the same Mogami cable for both. I think they sound about the same in terms of noise. An increase but a normal one I think.

9. About the problem I noticed. The QCM’s volume was at 100% the whole time. The QC’s is at a tiiiiny bit below 9:00. Holy shit, if this thing gets even noisier…

9. So it turns out the QC was on 14%. It’s fine though as cranking the volume up to 100% didn’t change the noise so I’d say that was a non-issue after all.

My conclusion: using the QC into the front of a high gain tube amp can be noisy AF. The QCM is much, much better and is on par with the VP4.

Addendum to testing above:

I decided to see if this huge noise difference also existed through my EV PXMs. It does and doesn’t. The QC is noisier than the QCM but I can barely hear it either way. I need to crank the EV’s volume and have my ear up near the speaker to hear the noise. So I think it’s a non factor in tha setup (through an FRFR type system) so perhaps that’s why not many people complain about noise issues.

Hm. I should probably check the difference, if any, through the amp’s FX loop. Duh.

The noise difference is still evident through the amp’s FX loop, but similarly to the EV’s I don’t think it’s an issue. I had to turn the amp’s master volume up to noon to make it obvious (ch 1 master controls it in a straight into the loop scenario). That would be super loud.

So to add to the conclusion above, if you’re running into the front of your high gain amp you just don’t want to be using the QC. Not sure about 4CM but I’d expect similar results.*

With the QCM you’d be just fine running into the front. So…

Welcome to the team, @Orvillain

* Fucking hell. Gimme a few minutes.

Verrrrrrrryyyyyyyy interesting!!! Thanks for doing this.

So yeah.... bear in mind the context I was originally testing in, which was both as an effects-only unit and 4-cable-method with a real amp, and I was comparing to Helix and Axe FX III, I found the QC drastically different. Like, world's apart from the other two units. Helix and Axe III were acceptable. QC absolutely was not.

Whereas when you use it into an 'FRFR' or 'poweramp' situation, not involving an amps preamp circuit, I think you'd definitely notice it less - although it is there as you say, the QC is just a noisy hissy buffoon.

If the QCM is better, I genuinely would be more open to getting one.

Only thing with your test was, going from the XLR out on QC was not what I was doing. I was using the outputs and the sends, via 1/4inch cable. I'm sure there isn't too much difference though.

 

[Orvillain]

@deadpool_25 if you could record the basic noise floor of each unit into a DAW and measure the levels in RMS and dBFS, that'd be interesting too.

 

[Orvillain]

I started a video review when I got my 2nd QC, and I have a shot somewhere of me comparing the noise floor of those units as heard in the room. But I lost heart in doing the video, and never finished it.

@deadpool_25 Another thing to think about, the VP4 input noise gate is quite aggressive by default as well. When you turn it off, it actually does get quite noisy. Axe3 and HX Floor were definitely quieter than the VP4 even.