QuadCortex Output problem with power amp + cab

Hello!

So I started my adventure with quax cortex recently and I am facing a bit odd issue that I cant seem to solve myself. Basically I see that quadcortex should run okay when plugged directly to power amp (standalone or amp power amp section) or just into input of a combo amp. Basically turning off cab sim should do the trick.

I am facing this issue that whenever I plug my quad cortex into amp+cab, power amp section of amp + cab or directly to power amp in boss katana I am getting sound like line6 spider or metalzone - high end fizz, lack of bass just high end pitched noise - everything sounds pretty much the same. I either have to use cab sim or hilow cut equalizer to filter out amp sims in the quad cortex to get any usable tone out of my rig. ( when filtered out it sounds pretty amazing)

I am not exactly what I am doing wrong. It seems like I would need to cut the signal to something like guitar range before feeding it into power amp/amp/combo otherwise I am ending up with this super digital, high end fizz that want to pierce my ears.

I am used to having my old boss gt-100 on the floor where to get rid of that high end fizz I just had to change one output setting to amp head - and that was it. So I am wondering now if that settings on ol’ boss was just a low and high end filter applied globally on modeler.

I am wondering if there is something wrong that I am doing? From what I see, that only amp sim or capture in the chain should sound pretty much ok when going this route without any hiccups.

I am using 2x12 loaded with Vinate30 speakers, solidstate amp head - old one by crate and boss katana combo. I tested that by pluging directly into either input or line in/power amp.

Thanks !

That doesn’t make sense with the 2-12 cab but doesn’t the Katana use a full-range speaker? Are you using stock presets or your own?

Hello,

Yeah, its a bit weird. Basically 2x12 cab should act like a filter by itself and it shouldnt be able to play above certain frequencies. Amp (clean channel or power amp section) is just way to make power to speakers.

Katana is not a full frfr speaker, its more like guitar speaker with some wider frequency range (this is what I read on the net)

I was trying almost every combination I could think of like :

Original presets without cab sim( turned off cab)
New preset with amp sim only

Best result would be a neural capture and that seems to work best without filers/cab sim and sound pretty much like it should. Global EQ seems not to affect them at all.

As workaround for cab sims I am using just global eq on output 3/4 only with hipass and lowpass filter and I get amp sound without cab sim flavour. Then I get cab flavour on sound depending what cab I am plugging into.

Weird is that - boss gt100 had same effect if I didnt select right “output” option. Just thin fizzy distortion that sounds the same on any amp sim. The output option seems to act just like EQ. Which seems to be the case.

Just like it would try to force signal that couldnt be handled by amp/cab

I have checked all outputs and imput levels and everything seems to be ok. No clipping. Also lowering outputs doesnt affect the fizzy/thin sounding. Removing high frequencies aboveb 5-6K seems to solve the issue right away.

A bit weird, just something I cant seem to be able to solve and similar thing was on old effects.

I do mot have experience with poweramps like oragne baby pedal or seymour duncan. Do they have some hilow pass filters built in?

Thanks,

I use low-pass and high-pass filters on every preset (especially important with overdriven presets), with the exception of acoustic presets. Remember that those models are created using a mic (or mics) placed directly in front of a speaker, usually in close proximity. Nobody listens to their real amp this way. You’re almost always at a distance and well off-axis which naturally rolls off highs and lows at your listening position. Don’t be afraid to use filters and EQ to get what you’re after. Why you’re having this issue with your 2-12 cab is a mystery, though.

What are your input and output settings on your QC? Keep input gain at 0 and dont run the output signal too close to red (clipping). It has pretty major effect on the high end.

Hey hey,

Thanks for responses. I am just using default settings for output. Nothing clips or hits any limiters.

As solution i set global eq on output 3/4 with some low and hi pass filters and it does the trick for me.

I am using Boss Katana mk1 which is something more like modeling amp with a weird speaker and old crate fw120 head (into 2x12 vintage30 loaded cab). Applying filters globally solves the issue perfectly. A bit weird is part with my old boss modeling effect - it had same issue untill aplying the output preferences that just cut high frequencies.

I would suspect that both amps are not so great and require some adjustments to the signal they can accept. For now I do not have clean power amp on hand to test, but if I get I will let you know. Thanks for help guys.

Also if you get your quad cortex did you guys had some presets saved in My presets? I bought my brand new, original packaging, foils, wrapper on power supply etc. and I had few presets already saved. Another mystery I cant get my head around.

Try the following……

1 power amp + cab - turn off cab sim and use TS instrument cable to the power amp.
2 katana - it’s closer to FRFR. At the end of the day it’s a powered speaker and should be treated as such. Use balanced TRS cable with cab sim on in the QC.

Hey hey,

Yes I tried that. In case1, It sounds like metal zone or line6. Aby distortion ends like this. I need to apply cab sim or eq with hi and low pass fiter(if I do not want cab sim flavour, just my own cab). When I have done that, it sounds great - like it should.

I will update this thread when I can get dedicated power amp instead of solidstate head and let you know results.

Thanks for help guys!

Glad to hear there’s progress. I’ll keep an eye on this thread for progress updates.

Hey, I am facing a VERY similar issue to what you did back in May. Did you ever find a solution to the issue?

Hey hey!

Sorry, for not updating this thread I just had my mind on other things around me and didnt get actual chance to post updates.

Basically - starting from the beginning I was able to solve the problem partially. The amps I have used before was old school Crate fw120h head and first gen katana 50W.

After a lot of digging, wiring and soldering I was able to figure out why those 2 amps sounded so bad and found some ways to remedy this.

With boss katana, I didnt have the version with direct plug to the power amp.
I found out that you can use :
Aux in and it sort of works.
Clean channel with some lower gain settings (not recommended)
or acousting guitar mode - which is preferably best one

Katana is a modeling amp and has weird sounding speaker by itself. Aux in option works okay, with amp sim and EQ block with low/hi pass filter (settings provided lower in section about fizz)
Clean amp option is the worst - as you get quad cortex modeling into another modeling -bad idea.
And the Acoustic channel - which seems to turn the katana combo into something more like frfr speaker(not full frfr, more like guitar speaker with some expanded frequencies) and cab sims seems to affect the tone quite nicely - but I sold this combo before I could dig deeper into this. I had this combo for few years and really really hated that speaker and the way it sounded. My old crate fw15 transistor combo sounded better.

This crate head o mine was like first type of modeling amp (not exactly how katana determined this types of amps but similar) that had digital section of effects in the chain before the signal went to the power amp section of the chain. This little digital thing just throws out all the signal from quad cortex and made it sound bad. The solution was to make a custom wire for this amp, use it’s combined fx loop and feed the power amp section of the amp from quad cortex. This worked as it should - I was able to lost that digitalness of the sound(well its hard to describe sounds in general, but it stopped sounding like nokia phone from 2005).

So, when I was able to feed the power amp and then straight to my homemade 2x12 V30 cab (if necessary cab is 4ohm/120W),

Fizz/metallic noises/high end mess

Okay so now I faced the issue about quad cortex sounding like metalzone cranked all the way up to 11. Basically this was the point that took me a bit of time to figure it out. How I understand the quadcortex works with its amp simulations - its more like just like a preamp (despite having master control in the amp settings). So when you have a clean patch with nothing in it (I assume you have not made any global eq setttings and your outputs are set to factory settings) and you add a high gain amp - and then feed that to the power amp and a cab you get basically overpriced metalzone.

To fix that fizziness, cheap sounding, lot of high end squels/fizz/metallic noises/shhhsshh etc you would need to clear the signal. Basically at the beginning of my journey with QC I was assuming that guitar speaker will “filter” frequencies that it can play and this was mistake. If you know how guitar speaker works (they actually can produce sounds over certain frequencies if you look on the frequencies chart) then the speaker will try to play that harsh sounding fizziness.

So back to signal → now to clear it out you would need to add EQ block after amp that is called low/hi pass (sorry I do not have QC with me now so no screenshots). I just use standard settings and change only low pass filter from 22k( or something like that) to 6600 or around. You can go higher or lower from that 6600 - this will affect how high end will react in the amp sim block - aka your treble and presence settings might be less or more affected - another tool in toolbox

This was a game changer - from metal zone it went to full boutique amp. Now its just play with the amp settings, volumes, master controls, EQs if you are into that etc.

I belive that the manual is a bit wrong about ditching the cab block after amp block - since there needs to be some signal cleanup . (you need to cut that signal into something more usable for guitar speaker. The low pass just limits what happens with certain frequencies about specific point and how they fade away. Its like trying to play 20-22khz signal into speaker that works in 75-6000khz range, something will go sideways. Just limit the upper part and done).

Currently I am using my quad cortex with a Harley Benton GPA-100 and my v30 cab or just one singe speaker like celection heritige or greenback( both 16ohm to put some load on the power amp) and this works amazing. 2x12 can knock walls and windows and single speaker setup is great for practice.

Set of tricks I learned about QC and this set up - and fiddling with my old amps.

  • Double check your inputs - make sure that if you use actual amp - you go straight to poweramp
  • If you use guitar speakers - do not use cab sim - but dont forget about low/hi pass filter instead
  • You need to make sure that your levels in QC are not clipping
  • I keep my master volume on QC in about 85% - not sure but I feel it works okay - and if needed you have a quick boost in volume available to you

@runlego I read you other post - dialing a good tone is pretty easy on QC if you get your head around it. I literally use super simple chain - noise gate - boost ( like marshall governor sim) - peavey 100 lead - low/hi pass filter i mentioned earlier - delay(if solo) - reverb( just to make room sound better)

If you use 2 cabs and each is 4x12 your power amp might not have enough power to pump those speakers. I use gpa-100 which is 100w at 8ohms (190 at 4ohms, about 50 at 16ohms) and it got plenty power to keep 120W cab rocking hard enough to damage speakers. You can get a feel of guitar amp rocking whole place around with “upf” at low end chugs (my kidney stones felt that :D) .
Even with a single speaker set up like greenback (with is 25W) you get it so laud that practicing on it is a bit to harsh for ears.