Quad Cortex with Real Amp

So, I got Mesa Rectifier Mini + Mesa 1x12 Cab for myself to have one real amp setup.

I thought, that I’d use the Quad Cortex as a Pedalboard with this setup by using the 4 Cable Method. But so far I have been little disappointed with this.

1st Problem:
When using 4 Cable Method I get some Dry Signal Bleed/phasing problem. I don’t know if it is a problem with Mesa FX Loop or Quad Cortex. But my tone clearly changes using 4 Cable Method.

2nd Problem:
I also tried to use Quad Cortex in Front of the amp. By doing this my tone is again changing vs going straight from the guitar to amp. With QC the tone has more low end and the gain is different, can’t really say what is changing, but the tone is not transparent when I use Quad Cortex this way.

So, yeah! So far I have had problems to get the Quad Cortex to work as a Effects Unit with a real amp. All the help is welcome, if I could troubleshoot something. My settings are stock in the I/O menu and Volume knob is at MAX. Quad Cortex FX Loop settings are stock when using 4 Cable Method.

Have you guys have these kind of problems if you’ve used QC as a Pedalboard with an Amp?

If you’re going to the amp thru the regular guitar inputs make sure you bypass the QC preamps by going out of the effects send on the QC.

Thanks man! I have to try this.

So to be clear I got this right:
Using QC in front of the amp I need to use FX Send as my output. Do I need to do anything else on the settings? Guitar to IN1 and OUT to Send1 on the preset Grid?

With 4 Cable Method
QC Send → Amp input
QC Return → Amp FX Send
QC Out3 → Amp FX Return

Does this 4CM setup bypass QC preamps as well?

I just double checked the QC Manual and according to that, using Pre Effects Only I should use OUT3, like I’ve done so far. Am I missing something?

Right, for the setting for in front of the amp. By doing this you are bypassing the preamp in the QC ( which are very good). Running a preamp into another preamp is not a good thing in this scenario.

I have a Great River ME-1NV which I’ve always used before buying the QC. I’ve A/B the ME-1NV against the preamps in the QC when recording guitar and bass and I can hear no discernible difference so I use the on board pres. But if I’m recording vocals I still prefer the Great River.

Yes in the 4 cable method using your patching above you are bypassing the pres.

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My Mesa DR (early 2000s) uses a parallel FX loop which has send and return mixers etc., not the best effects loop and especially not great for 4CM. I had similar issues where the amp’s loop prevented me from having a good experience. I then tried 4CM using an older 5150 which uses the standard serial FX loop and that worked perfectly. I used the 4CM preset that is included in the QC factory presets as a base for my own presets using 4CM. Otherwise, running QC in front of an amp (in my case, both the DR and the 5150) did not sound that great on the clean channels and figure those amps are just not great amps for modelers using that way.

I tried the Send 1 output in Pre FX setup. But to me that also changes my tone.

The attack and clarity of the amp is better when just my guitar is plugged in to it. With QC the tone gets little more low frequenzies and is a bit softer.

To be clear. The change in tone is not dramatic, but it is there. I don’t know if using real pedals does this as well, ’cause I don’t have any at the moment. But using QC does affect the overall tone a bit IMO.

I replicated all of your issues, and that is part of the reason I unfortunately had to sell the unit. It wasn’t up to snuff when it comes to 4cm with a real amp. Maybe they will fix it.

I know we had a short discussion about this on TGP. For me it all comes down to how and where the efx loop of the amp is situated. I have a very good FRFR box from Blueamps which I recommend highly. But I wanted to go with a real amp as an even better alternative which I found in a very clean Two Rock amp - the best (and most expensive) pedal base I ever had. I went with a QC preset (sure enough without amp and cab block) in the amps PASSIVE efx loop - this resulted in tone suck and a much lower volume. Until I found out that the efx loop a) sits behind the Master Volume b)needs to be buffered. But I did not want to be bothered with extra gear.
On a Two Rock forum some users advised me to just give a damn and go straight into the front of the amp, not dealing with buffers or 4cm, because they went the same route. That’s what I ended up with: a QC preset without any amp, preamp or cab blocks, different boosts and overdrive captures to colour the sound, compressor, time based efx - and all that into the front of the amp. The OUT 3 of the QC needs to be turned up to 5.8 db to match the volume that the guitar has going straight into the amp. Simple thing, sounds very good. Only real high quality pedals into the amp sound a bit better to my ears and fingers.

So, there seems to be two ways of doing the 4CM Method and I suggest you to try which one works for you and your amp:

”Official 4CM Method”:
QC FX Send 1 → Amp input
QC FX Return 1 → Amp FX Send
QC Out3 → Amp FX Return

This is the one, that you can find in the manual. For my experience this connection is hotter (more gain) and the feel of the amp is different, when playing.

”The other 4CM Method”:
QC FX Send 1 → Amp input
QC FX Return 1 → Amp FX Send
QC FX Send 2 → Amp FX Return

Note: Use SEND 2 as Output on the Preset Grid. This connection method works better for me. Amp has the same gain as without the QC and the feel of the amp is right.

I didn’t change any of the Output(s) gain settings or input impedance. All of the I/O settings have been left default.

Also this INFO is good to know:
Output level will change depending on which cable are you using:

XLR Outputs 1-2:* +9.5dBu*
TRS Outputs 3-4:* +15.5dBu balanced, +9.5dBu unbalanced*

So, more output level is expected if you connect TRS cables to outputs 3 and 4.


Is this “other method” ok and safe to use?

Of course, the only difference is using QC FX Send 2 → Amp FX Return instead of QC Out3 → Amp FX Return. Both methods will work although NDSP recommends to use their 4CM method which follows their factory preset to make things easier.

Actually your “inofficial” method prevented me from selling the QC as the official method adds quite some different feel and input “lag”.

I hooked it up to a 5150iii 50watt el34.

Thanks a ton man!

Btw. The midi switching of 5150 channels works like a charm and immediate.