I would be interested in the ability to load cabinet IRs that I make, and apply them inverted on one (or multiple) output.
The ability to generate that correction IR in QC would be the extra bonus version of that.
End goal being to use existing bass or guitar cabinet(s) as quasi, semi-inaccurate FRFR cab. Right now doing so is a very home-brew undertaking.
Can you provide more detail on this request? What do you mean by “correction”?
You can already load your own custom IRs through the cloud.
I’m not sure what you mean by “inverted”, but the IR blocks in the QC let you do 180-degree phase reversal.
Right. Glad you asked.
So there are some people out there, from what I understand, are creating IRs, and then “inverting” them in a software tool so that when applied, they bring a particular cabinet system to as close of a flat response as can be achieved with the actual physical properties of the amp/speaker/cabinet. The inverse idea of imparting characteristics via IR…removing them.
Of course there are things that can go wrong with this (your IR will include the power amp characteristics), but I believe anecdotally from what I have read that the imprecise nature of this method are acceptable in practice.
But apparently people have been doing this to improve the freq response of lower end FRFR cabinets, and also to make, say, a standard Marshall 4x12 usable to a degree for adding other cabinet IRs too.
My own interest is using this for bass. Standard PA based FRFR solutions are usable to a certain mid-volume level for bass modeling, but some bass guitar cabinets are designed from the start as being somewhat more accurate, those being two-way (and even sometimes 3-way) designs. But yet still not marketed as true FRFR (Accugroove, GR Bass). I have Phil Jones cabinets, which are less colored than vintage bass cabinets, and supposedly react well to this sort of EQ correction.
So having a closed loop system on board the QC to do this job could be wonderful for all users I feel.
It doesn’t even have to be IR based, to be truthful. Just sine sweeps fed into a mic meant for calibrating systems, generating EQ data that could be applied to any block (or likely what would be best, an output block destination), would be fantastic.
You can already do that by using an extra IR loader with your inverted IRs. Or is your feature request to invert the IRs on the QC itself?
To be able to invert the IRs on the QC itself, since it has the ability to generate them.
But again, to be truthful, it doesn’t have to be specifically IR’s, just a simple sweep and curve generation would serve the purpose as well.
I was not able to find a piece of software on Mac to ternate inverted IRs. Invert the phase on IRs, yes, but invert them in the frequency response sense, no.
After you explained what you wanted to express with the term inverted I find it attractive but to consider the work to create a useable IR and then the fact that the cab sounds different in another environment makes it less usefull. Just theoretically speaking.
Direktor - I would take a different approach to generating your tuning of choice.
Start by measuring your cab’s complex frequency response with whatever measurement mic - even a cheapo ECM8000/etc will suffice. (Dual-FFT measurements ala Smaart are my preference for efficiency’s sake, but REW-style sine sweeps will get you the same data.)
You can then design an appropriate IIR/FIR correction with FIR Designer (paid) or rePhase (free), taking into account QC’s 1024 sample IR length limit. The former will run on macOS natively; the latter might run via Wine. (Spinning up a Windows VM via VirtualBox/Parallels/VMWare is another option, though certainly a blunderbuss solution.)
Bear in mind that this approach is still subject to the cab’s existing directivity characteristics! It’s relatively simple to achieve flat magnitude/phase on-axis; less so to achieve good off-axis behavior.
Speaking of nontrivial FIR tuning: if you’re in the mood for a good read, have a peek at Dave Gunness’ 2005 AES paper on FIR transient response correction!
Hey Compu,
Thanks for chiming in on how to do this short of NDSP making an idiot-proof built in solution.
I’m in general aware that the whole enterprise of trying to flatten out cabinets with completely different design goals than flat response is somewhat of a fools errand, but I think probably even getting in the ballpark would be enough to make me happy and allow me to hear characteristics of my fav modeled/captured amps, etc.
I do know two of my powered wedges have curve characteristics that just plainly do not sound like a bass cabinet…I can identify by ear the largest parts of what’s wrong with them (huge bump around 150hz) but trying to tune by ear with parametric is just eluding me.
Id rather just get a good FRFR bass cab, or one that is considered “hi-fi” (GR, Epiphany, etc) and do my best to flatten in software.