Matlab.@FractalAudio what program are you using to generate the graphs from the or files?
This is very cool stuff.
Matlab.@FractalAudio what program are you using to generate the graphs from the or files?
This is very cool stuff.
Do you do all your algorithm development in matlab?Matlab.
The reflections are slightly delayed in the real world but an ir captures that info the same point in time. these reflections could be the cab itself even when no walls or floor are present. that's what different types of cabs have different response with the same speaker. of course i'm just guessing and not an audio engineer.
Aren't these artifacts mirroring what typically happens in a studio environment? Maybe the "free space" ones would sound "better". I'm just pointing out that it would no longer be the sound of a mic'd cab as we know it.
looking forward to the results of this thread. Maybe we'll get reflection-free IRs and wall/ceiling/floor distance parameters
Huh? You're not supposed to use an IR with a real cab. Everyone should know that.Yep, it takes about 3.? meters for a 100hz signal to complete one cycle. How this effects an ir measurement I have know idea. I do know that when I set up a fractal amp using a real cab and then switch to an ir...any ir...I have a bass problem. The opposite is also true.
Please note that I am still on the axeII and this problem is much less prevalent in the latest firmware.
I always felt the same way! Actually, a couple of IR's that Ive purchased and really love, have a tiny bit of early reflection on them. It took me a while to realize it. Was checking preamps, interface, etc and eventually when I shortened in the cab block..... Voila!!!I've been experimenting with IR length lately and keep finding that I like a shorter length. So I gave some thought to it and I think the reason is that a shorter IR trims off the early reflections.
As I stated over at TheArgumentGear Page:
I'm going to work on an auto-correlation display over the coming days and see if that can help in identifying early reflections.I always felt the same way! Actually, a couple of IR's that Ive purchased and really love, have a tiny bit of early reflection on them. It took me a while to realize it. Was checking preamps, interface, etc and eventually when I shortened in the cab block..... Voila!!!
Of course you are absolutely right, ...when you measure the frequency response with a microphone. But when a play my marshall, I hear all those frequencies responding in a room. Now if I record that sound and make a cab (ir) out of it it may be fine if your listen on headphones or any medium that excludes a room. But as soon as you play through live system, you are doubling up on the room anomalies.I get where you're coming from, but think about it: which of the many EQ curves that the speaker produces — even in a reflection-free situation — is the one "inherent to the speaker?" They're all inherent to the speaker. As you move off axis, different cabs change their sound in different ways. Even if you choose one EQ curve as the starting point, you can't apply a standard formula to figure out how the sound will change at, say, 30° off axis. That's why people take multiple captures at different angles when they're shooting IRs.
No, I'm just talking about the distance it takes for 100hz to travel one complete cycle. Now whether or not it effects the curve we capture from a cab closer than that distance, I have no idea. Off hand, it seems like we would need a complete cycle but I don't know.Huh? You're not supposed to use an IR with a real cab. Everyone should know that.
The excursion of a microphone diaphragm is measured in thousandths of an inch. That's a tiny fraction of a wavelength at any audio frequency, and its effect is inaudible.That mic capsule is moving constantly back and forth as it's sending signal, that's a source of modulation/distortion.
How would you capture the IR of a room? You'd need a speaker of some kind, with its own direction-dependent frequency response. That would color your results.What if you took an ir of a cab that included the room and then subtracted just the ir of the room?
Awesome!!! Yeah for this particular IR, it wasn't even evident in clean tones. It was only when adding drives. IRs really are an interesting thing. Do you think there is an advantage to capturing in a dead roomI'm going to work on an auto-correlation display over the coming days and see if that can help in identifying early reflections.
Well, you would need a perfect speaker, or close, located at exactly the same place at the cab with the same perfect mic located ar exactly te same place as the before. Less than perfect solution , eh.How would you capture the IR of a room? You'd need a speaker of some kind, with its own direction-dependent frequency response. That would color your results.
And where would you place the mic and speaker? Your choices would influence the IR capture.
There is no single inherent EQ curve of a room, just as there is no single inherent EQ curve of a guitar cab.
Because it doesn't. Even an anechoic chamber isn't as good as using a large space with reflecting surfaces far away.
Awesome!!! Yeah for this particular IR, it wasn't even evident in clean tones. It was only when adding drives. IRs really are an interesting thing. Do you think there is an advantage to capturing in a dead room
@guitarmike Serious question-do you understand what an IR is and how it works? Do you understand the speed it is done at? The 'fast IR' you speak of, what speed is THAT done at? At the same 100hz, what time do you think does it take a reflection to happen in say an average sized room?
Also, how do you propose to 'average out' the IR when moving the mic will result in a different IR? What is the 'perfect IR' then and how do you achieve it?
How do you propose to do this 'subtraction of the room IR'? What are you using to take the IR with?
I suspect by researching and answering some of these questions you will have a better understanding of what is going on, and will answer yourself a lot of your questions and concerns.
Phasiness can also be caused by a lot of other factors, first of all mic position relative to the speaker.Something still causes phaseyness (or lack of clarity) in some irs, even prior to the early reflections, I can hear it. Cliff has made a lot of advances in that area because it used to be worse. The other few modelers with ir loading I've heard have it also (probably more).