Suggestion to L6 - How about a "NO MIC" option

[billlorentzen]

I'd like to suggest for future versions of Pod, that there be a No Mic option. This could be considered, "What your ears would hear" and would add no color to the sound.

 

When users set up a patch, they typically start with the amp model, tweak the drive and tone, then if they're not quite satisfied, the cab, then the mic, then if necessary add an outboard EQ. Quite a few steps, but I suppose in the quest for realism, it makes sense.

 

I think I am what one would call a power user after several years of steady gigging and some recording with the Pod HD. I recently swapped out pickups in one of my guitars and started from the ground up with new patches. I found that selecting both the amp and cab models was intuitive, gratifying and fast. However, I found the mics sometimes more in the way of the sound I was looking for than helping with it. Sometimes none of their EQ curves were what I wanted.

 

Let's consider this logically. In the physical hardware world, amps and cabs and FX are part of the tone creation process and frankly part of the art. However, the mic used by the live or studio engineer is actually more of an obstacle or X-factor to the player than an asset. To the engineer, it is a necessary evil and is used as a shaping tool (although, as a professional engineer with decades of experience, if I had an option of a perfectly flat and non invasive mic and pre, on most sources, I would probably try that before anything else). So, why not give that option to the Pod user?

 

For my purposes, if I need more tone shaping after setting the amp and cab, a finite impulse response (FIR) EQ with no phase distortion would be the perfect last step in the tone creation process, rather than a copy of the EQ of a mic. After all, we are in the digital realm, so why not use its advantages? Even one of the EQs in the HD is acceptable, although I am not a big fan of their interfaces to be perfectly honest.

 

What do you all think?

[Rewolf48]

There was a big discussion about this in order to get the Cab In The Room sound on the old forum. Of course I can't find it now

 

The conclusion at that time was that it wasn't possible because (as above) it had to be measurable, and the measurement is from the Mic.

 

I thought at the time that I had suggested (and if I didn't I am suggesting it now) that the signal from a Power Soak or Speaker Simulator would be a proxy that didn't require a Microphone.  I am talking about a quality device such as "THD Hot Plate" or a Palmer Speaker Simulator.

[Rewolf48]

No you are talking about the opposite requirement.

 

The Sound Field DSP logic is taking a "pure" signal and treating it to sound as if you were in a specific environment (or something like it).  It is a combination of filtering, phasing and delays and is actually implemented using Impulse Response and Convolution.

 

The true "No Mic" option means that your FRFR system will sound exactly the same as if the real cab was sitting in the room, rather than the signal from a microphone against that cab.  The holy grail of a modeller for Live use is that it sounds as if the Amp was there rather than being miced up and reproduced on studio monitors.  Of course the audience has only ever heard the miced version, it is only the guitarist who wants the Amp In The Room sound. Even the Axe-FX is criticised because it cannot do Amp In The Room.

 

Theoretically it is possible to get an Impulse response that does represent just a cabinet, but it is not very practical because you need to cancel out the microphone used to measure the response of the cab.  Which is reverse convolution and is a supercomputer sort of thing.

 

If not a Power Soak device the other option is to use a calibrated "reference mic" in an anechoic chamber (no room).

 

But from the realist perspective if you really need that Cab In The Room sound ... then get a Cab and stick it in the room.  DT series or power amp and cab combination. 

 

Personally I find I can get acceptable by turning down things in the Deep Editing Parameters especially Master Volume, E.R. and Resonance. I know it makes the cab simulation more "dead", but that is the point, because the FRFR is still a speaker in the room.

[Digital_Igloo]

Mics are definitely a critical component in the way we capture and model cabs, but that's not to say an extremely flat, transparent mic (such as those made by Earthworks) couldn't be included in the list.

[Digital_Igloo]

SM57s aren't transparent at all (a good thing!), but they're used to mic amps on more records than the others, so people are probably most familiar with their sound.

[gunpointmetal]

I second the "No Mic" option....one of the most-used features of my old BOSS GT-8/10 boards (too bad the amps were terrible compared to the HD-series). 

[Digital_Igloo]

To be honest, none of them (by design), but I'm probably pickier than most. :)

[billlorentzen]

Some interesting and thoughtful replies!

Nico, you suggest that the mic is a necessary feature because something needs to capture the acoustic energy. When I read your post, at first I thought you had found a flaw in my suggestion, but on further reflection, I think I disagree. First I have a question, which may only be answerable by Line6, but some of you guys seem to know more than me and maybe you can answer: Was each cab models captured by each microphone? In other words is every cab/mic combination a unique model or are the cabs and mics discreet individual elements in the signal chain?

 

For both simplicity and fidelity, my guess would be that they should be complete combinations, but my gut tells me they are not. Either way, there is a solution.

 

If they are a single component, then they could be modeled with something like the Neumann KU 100 Dummy Head Binaural Stereo Microphone System, in an anechoic chamber. Or alternatively just use a flatter mic (though it may not flatter the sound ;-)

 

If they are each integrated mic and cab models, the mic could be subtracted from the model by some crude method like reversing phase of the mic model. I'm sure software engineers would blanch at my simplistic approach and could come up with a more sophisticated and probably more accurate approach, but I think we get the concept.

 

In any case, my ears tell me the mic models are largely just adding EQ and as such they should be removable, and I would like the option. For engineers capable of developing such a wonderful system as the HD, this should not be an insurmountable problem.

[Rewolf48]

RIBluest,

 

Impulse Response + Convolution adds a "listening environment" to a signal, it is about superimposing the sound of say a Cathedral onto a miced up choir so that it sounds as if you are listening to them in that Cathedral. The really good ones allow you to use a reference mic and measurement software to set-up various filters and the cancel out as much is possible of the room you are listening in... but it cannot be eliminated completely even with perfect processing and inverted signals to cancel out reflections it is still only accurate at the exact position where that reference mic was located and for exactly the same arrangement of things in the room.

 

"Amp In The Room" (AITR) is about having it sound as though that choir is singing in person in the room with you.  It means removing all of the filtering inherent in the microphone, pre-amp, ADC and reproduction stages, plus the ambience that was present in that room when they recorded (which actually changed as they moved around!).  

 

The room ambience is made up for in the AITR situation because you are listening in a room - it is about it sounding as if someone had shifted that 2 x 4 x 12 stack into the room.  Except that when you do a patch change it sounds like the Blackface Face twin instantly replaced it.

 

But it is an impossible dream - to start with guitar cabs are really directional and the sound on axis is very different to the off axis sound (which is why many amateur guitarists that tweak sound off-axis really sound like rubbish) and your FRFR solution is designed to give an accurate sound over a wide dispersion pattern.

 

As you say if you decide that you must have an AITR sound/feel then the compromise is that you select Cab that you like and stick to it using that DT or whatever.

 

 

Billorentzens post has just appeared, and yes the use of reference mic and anechoic chamber is the best compromise that can be achieved for AITR when using FRFR.  And is what I thought that Igloo was suggesting yesterday.  Probably sound weird in headphones without any room ambience, but that is what reverb is for.

[Digital_Igloo]

No inside information here, but I'm guessing it represents the original test mic Fractal used to capture the cabs.

[billlorentzen]

Mics are definitely a critical component in the way we capture and model cabs, but that's not to say an extremely flat, transparent mic (such as those made by Earthworks) couldn't be included in the list.

Since we have a Line6er on the thread, I've got a couple questions which I hope are not asking for proprietary info:

 

When the cabs are modeled are they sampled at various volume levels?

 

Is it possible to "subtract" an element from a sample, e.g. the mic? If that's not possible, I really support the idea of adding a flat omni mic or a test mic to the list. As a recording engineer, I realize they may not always be pretty, but I've gotten good results with fairly flat condensers like an AKG 414, and even a 451.

 

By the way, another option I think might be cool to explore is the binaural head mic. It would probably work best in a pretty dead room, but if you want realism and the true sound of the amp, nothing could be closer, IMHO.

[Digital_Igloo]

There are two primary methods of capturing mic data:

 

1. Put up a bunch of mics in front of the cabinet and capture them all

 

2. Put a single ultra-transparent mic (Earthworks) in front of the cabinet; then apply mic model compensation curves to the result

 

Number 1 is a lot more work, likely a bit more accurate, and IIRC, how POD HD was done. Number 2 is a faster to implement and probably a bit more consistent.

 

The binaural head mic is a really interesting idea, although they'd really only apply to stereo cabs, which are twice the DSP load. That and unless you're listening on headphones, there'd be a kind of "amp in a room in an amp in a room" effect. Still, it's worth a conversation with our lead sound designer. $100 says they've already tried something like that—might've seen a Neumann KU-100 floating around the studios.

 

As for "subtracting" an element from a sample, it's a lot easier if you used method number 2 above and therefore, knew exactly what mic model curve was added. With a bit of work, you can come close to zeroing the mic out. But there'd be no point if a test mic was used to begin with; just choose that.

 

/not a sound designer, not a DSP engineer

[billlorentzen]

Thanks for the insight. That's kind of how I figured it.

 

I would appreciate if on the next iteration (is that even necessary?) you guys would include a flat Omni mic option.

 

By the way, do you know if the samples were made at different volume levels on the cabs?