Quad Cortex mini: Insane amp modeling power for the discerning guitarist

A warehouse of guitar gear in the palm of your hand.

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[ktmglen]

Somehow the music tech industry has done a uniquely good job of rejecting all the nonsense going on elsewhere in tech.

There's a vibrant market of small companies and even individuals making cool products, especially since the advent of cheap, powerful DSP hardware. (Although unfortunately tariffs are kind of throwing a wrench in things, especially after the post-COVID slowdown.) Even Aurich seems to be involved: https://modulargrid.net/e/hakai-labs-turbocharger.

On the computer/DAW side, subscriptions and restrictive licensing schemes exist, but can mostly be avoided. Resale of software purchases is frequently possible even where not explicitly required by law. It's kind of a weird window into what could have been in the greater tech industry if everything hadn't consolidated around just a couple major platforms intent on extracting money in every way possible.

The tariffs definitely are messing things up.

I wanted to do something stupid--trigger a sound effect on my PC by hitting a drum pad. The four channel edrumin for $159 looked perfect until I saw the tariffs: $35 in tariffs, not great but not a deal killer, plus $50 for FedEx to collect the $35. That was a complete deal killer.

So now I'm messing around with some op amps and an RP2040 microcontroller. If anybody wants a single channel drum pad to USB MIDI note on message doodad, it'll be on github eventually if it works out.

Edit: I'm not a musician so I have no need for a complete e-drum kit although that might be the easiest and fastest way to get to the end state of this project.

 

[Corporate_Goon]

The 45-second boot time sounds ridiculous, not something you pull out just for a quick noodle (the Anagram starts in a couple of seconds, it really is amazingly well-tuned for being Linux).

I use a similar Headrush Core which has about a 30-second boot time and it's really not an issue. You flip it on and while it's booting you grab your guitar, plug it in, turn on your speaker, sit down, and you're ready to play. At worst you're waiting a few seconds before you get sound.

I really can't emphasize enough, as a working musician, what a game changer these great modelling pedalboards are. As noted above I use a Headrush Core, the other guitarist in my band uses a Quad Cortex - the flexibility they give us is really fantastic, and they make gigs so much easier to prepare for. No more carting 100 lbs amplifiers on stage, you just throw the board in a bag, grab your guitar, and you're off to the races. You can set up individual "scenes" or specific boards for each song so you're always getting exactly the tone and effects you want, instead of having to manually switch your reverb, delay, distortion, etc. all individually, you can switch entire scenes with the press of one button which is a huge cognitive load off in the middle of a set, and they make live performances sound way better as well, as you're going straight into the soundboard and giving the sound guy control, and he's not having to fight your on-stage amplifiers to find a balanced sound, which in turn helps hugely with on stage microphones getting clean vocal signals without feedback or contamination from other stage sounds.

Both the headrush and quad cortex also have microphone inputs and allow you to run effects on your vocals easily, which has been fantastic for me, as I play flute as well as sing, so I can apply fun long delay tails to my flute, or simple slapback delay and a bit of reverb to my vocals, which really elevates the live performance as well.

 

[Spud Spudly]

I was waiting for the part about usability and I know this is my problem but that sounds like a completely miserable experience. I want simple to use gear. I would spend days learning how to use 10 percent of the capabilities and then have to relearn it again at some point. And there is such a thing as too much choice. I have real amps and various amp simulators on an iPad and still I use my simple Valetron Rushhead Max headphone amp a lot because it's all knobs and switches - no buttons to memorize.

 

[mikehihz]

Veteran of the skeuomorphic experiments of the MI industry here... Guitar players are an interesting lot, they really value the skeuomorphic nature of software UI. If a plugin is supposed to sound like a 1968 Marshall Superlead SN 12301, well, hell, why doesn't it <look> like the front face of the amp. Gigging musicians are very much the same, and I count myself in that camp: color and abstract shape aren't enough visual cues for me to use something when I have paying people in the audience. I have 3rd party evidence that shows only a small part of the MI customer base is willing to put up with a representational UI instead of a skeumorphic one. The pros already have the Fractal stuff and investments in workflow and patches so they won't shift but I think they are an outlier serving the top end of the market.

Now that the generation of rocker that birthed that iconically designed kit is rapidly heading toward the grave, we might see a shift. But until their discretionary income shifts to digital natives who have never lugged a Fender Twin Reverb up a few flights of stairs, I'm guessing the Quad Cortex Mini is going to be a niche player of bedroom twiddlers, and on the opposite end of the market from Fractal.

 

[LG11]

The construction is pleasingly robust, and the quality and feel of the stomps is great. But there's not a huge amount of space between them, and I often misstep, especially with the upper row of switches - gotta practice doing the stomp dance a bit more I've seen a lot of videos of people putting oversize stomp caps on the buttons to increase the landing zone size - I might try that too.

And there's a big LCD screen to crush with your thrash-metal boots should you misstep... but I've personally never had that problem with my old-folks classic rock band! But if you kill that screen, you're in a really bad place.

And finally there is quite some surface area covered with ventilation grills on the two sides and underside, so if you've got a audience liable to spontaneous moshing - or anything else that might cause drinks to go flying - you might want to add some extra spill protection somehow.

Thanks, much appreciated! The screen is the bit that I'm a bit anxious about. That, and the ventilation (that I hadn't even considered). Still, I'm very tempted to go for this one.

 

[A Man A Plan A Canal Panama]

Wow, what fun! Appreciate the thorough review. Enjoyed your demo song, too. The range of tones is amazing and the authenticity is so excellent.

But I'm reminded why these days it's all acoustic guitar for me.

Friends make fun of me because most of my instruments have pickups and preamps but the 9v batteries have been dead for years. Never plug in. keep forgetting to remove the old batteries when I change strings. Oh well. Next time.

 

[ChrisRed]

I don't know that I'll be running out to get this piece of kit just yet. Wrist injuries have kind of ended my guitar phase. But I would be really interested to see something like this intersect with the desktop hifi Class D amplifier craze. It would be cool to see Wiim, Fosi Audio or Douk put out a hifi pre-amp version of this focused on modeling vintage hifi receivers, amplifiers (integrated, mono, tube), and/or speakers. Modern room correction software should be able to assist in getting the actual output to match what's being modeled. But it would be super cool to just select a preset for 70's rock that modeled a Pioneer SX-1250, Marantz 2600, or Sansui G-33000 reciver with a pair of JBL L100, Pioneer HPM-100 or Large Advent speakers. And do it beliveably through a Fosi ZA3, and a pair of sub $500 monitors.

This is such an incredible idea I'm amazed there isn't already a product out there.

Seriously though, why the hell not - unless the hifi mafia have killed it because all the presets are the same and it exposes the snake oil

 

[KoshcheiTheDeathless]

Thanks for the excellent review -- also really glad to see music technology included in Ars.

Beyond playing really big/fly-in shows with choreographed patch changes across the gig, these cater really well to the bedroom musician who doesn't yet really know what s/he wants.

To address the latter category, as a jaded musician with >40 years of playing under my belt, my only criticism of these devices is that they abstract away the fact that there are actually only a few musically meaningful choices that a guitarist/bassist can make about their instrument, effects, and amp.

For example:

1) On the amp side, there are only really two tone circuit topologies: Fender and Baxandall/James. If you know which you're dealing with, you can dial pretty much any amp to sound the way you want.

2) On the effects side, the same holds true. For example, if you're shopping for a bucket-brigade style chorus, regardless of what the packaging says, it's basically a tweaked BOSS CE-2. If it's a three knob overdrive, it's probably an Ibanez TS-9.

3) On. the instrument side, it again holds true. If it's a 24 3/4" scale solid body with humbuckers, no matter how it's shaped, it comes from the Les Paul family and will sound a lot like one, accordingly.

I'm not suggesting here that a musician shouldn't explore what's out there when searching for their voice (or use a tool like this one because it's legitimately very useful), but rather to be aware that beyond the fundamentals, they're shopping for nuance.

 

[IPunchCholla]

Thanks for the excellent review -- also really glad to see music technology included in Ars.

Beyond playing really big/fly-in shows with choreographed patch changes across the gig, these cater really well to the bedroom musician who doesn't yet really know what s/he wants.

To address the latter category, as a jaded musician with >40 years of playing under my belt, my only criticism of these devices is that they abstract away the fact that there are actually only a few musically meaningful choices that a guitarist/bassist can make about their instrument, effects, and amp.

For example:

1) On the amp side, there are only really two tone circuit topologies: Fender and Baxandall/James. If you know which you're dealing with, you can dial pretty much any amp to sound the way you want.

2) On the effects side, the same holds true. For example, if you're shopping for a bucket-brigade style chorus, regardless of what the packaging says, it's basically a tweaked BOSS CE-2. If it's a three knob overdrive, it's probably an Ibanez TS-9.

3) On. the instrument side, it again holds true. If it's a 24 3/4" scale solid body with humbuckers, no matter how it's shaped, it comes from the Les Paul family and will sound a lot like one, accordingly.

I'm not suggesting here that a musician shouldn't explore what's out there when searching for their voice (or use a tool like this one because it's legitimately very useful), but rather to be aware that beyond the fundamentals, they're shopping for nuance.

As someone who is using these to figure out what I want, do you have a primer on amp circuit topologies/pedal architectures? I've found a foundational sound for bass that I like so I don't need one there, but something that breaks down those elements and relates them to specific examples on the market (like you did with amp topologies and bucket brigade chorus) would be great. Some makers explain this in their descriptions, but for most it is just flowery marketing speak (where every single product lauds its ability to get the bass to cut through the mix).

 

[KoshcheiTheDeathless]

As someone who is using these to figure out what I want, do you have a primer on amp circuit topologies/pedal architectures? I've found a foundational sound for bass that I like so I don't need one there, but something that breaks down those elements and relates them to specific examples on the market (like you did with amp topologies and bucket brigade chorus) would be great. Some makers explain this in their descriptions, but for most it is just flowery marketing speak (where every single product lauds its ability to get the bass to cut through the mix).

It'd be a good idea to come up with one and become a consultant for aspiring guitarists trying to overcome FOMO-driven GAS. But unfortunately no.

I did do a bit of digging around and on the effects side, check out Josh's stuff on the JHS YouTube channel - he knows the history and he celebrates it, rather than trying to pretend that it's all black magic. He talks about the history of each circuit and how they've been adapted/tweaked/evolved. Spoiler: Excluding fuzz, phaser, univibe and a few others, a staggering amount of effects were designed by BOSS (Roland).

On the amp side, I couldn't find anything as useful, unfortunately. In this case, read widely and try some examples out in different music stores to see what tickles your ears. For bass, the Bax/James tone stack is predominantly Ampeg and Traynor (the YBA 100/300), and a Fender topology is pretty much everything else. Personally, I REALLY like the way a Rickenbacker sounds through a Bax tone stack (Traynor YBA-100) with a slight boost to the mids around 900Hz. Example:
View: https://soundcloud.com/koshchei-1/promenade-no-1


PS - if you want the bass to cut through the mix, cut everything 60Hz or lower on the amp and boost the mids a touch in the 800-1000Hz range. Bass frequencies take a LOT of energy to produce (hog all the amp's power), conflict with the kick drum, and don't sound all that good. Also, put the amp on a milk crate so that it doesn't acoustically couple with the stage and turn the venue into a woofer.

 

[djgrowers]

I'm trying to decide if I have any qualms about profiting off the hard work of the original amp and cab designers (I know other companies are emulating the originals through circuit simulation etc., but not quite at the scale that Neural DSP are) It's not as bad as the blatant plagerism in other fields of AI, but still. I suppose if the original hardware is no longer available it's ok.

 

[Outlaw Shark]

Wrist injuries have kind of ended my guitar phase.

Maybe I can give you some encouragement here. I suffered severe nerve damage to my right arm decades ago (ejecting from an F-4 that is in an inverted spin with both engines dead can do that to you). It took me years to be able to hold a pick well enough to even be able to play and a couple of decades until I could play well enough that I could relatively happy playing guitar again. I haven't done a gig since the 1970s, but that's fine since I still can't play as well as I used to. I sometimes play for my wife and occasionally for relatives, but mostly it's to put me in my happy place. See what you can do within your limitations. You may be surprised.

 

[IPunchCholla]

It'd be a good idea to come up with one and become a consultant for aspiring guitarists trying to overcome FOMO-driven GAS. But unfortunately no.

I did do a bit of digging around and on the effects side, check out Josh's stuff on the JHS YouTube channel - he knows the history and he celebrates it, rather than trying to pretend that it's all black magic. He talks about the history of each circuit and how they've been adapted/tweaked/evolved. Spoiler: Excluding fuzz, phaser, univibe and a few others, a staggering amount of effects were designed by BOSS (Roland).

On the amp side, I couldn't find anything as useful, unfortunately. In this case, read widely and try some examples out in different music stores to see what tickles your ears. For bass, the Bax/James tone stack is predominantly Ampeg and Traynor (the YBA 100/300), and a Fender topology is pretty much everything else. Personally, I REALLY like the way a Rickenbacker sounds through a Bax tone stack (Traynor YBA-100) with a slight boost to the mids around 900Hz. Example:
View: https://soundcloud.com/koshchei-1/promenade-no-1


PS - if you want the bass to cut through the mix, cut everything 60Hz or lower on the amp and boost the mids a touch in the 800-1000Hz range. Bass frequencies take a LOT of energy to produce (hog all the amp's power), conflict with the kick drum, and don't sound all that good. Also, put the amp on a milk crate so that it doesn't acoustically couple with the stage and turn the venue into a woofer.

Thank You!