What exactly does Processing do?

[Ben Lagman]

What exactly does it do? I know that it changes the sound coming of of a speaker, but what goes on in the processes? Apologies for the dumb question, but whenever I use speakers with processing, I just 'use them' and never put in any thought of what happens. I know that sometimes EQ can be applied, among other things, but what does a processor do to the signal being processed? For example, Vertecs with V5, and Vertecs without it. What does the processing do to make the Vertecs with V5 presets make it sound so much better than the ones without it?

 

[Jeff Babcock]

Re: What exactly does Processing do?

Hi Ben,
In the case of Vertec V5, it makes use of FIR Filters.

Here's Dave Gunness' AES paper about *some* of what is achievable with this. It is worth reading. Not a trivial subject though.....
www.eaw.com/info/eaw/technical_papers/nt_whitepaper.pdf

 

[Ryan Lantzy]

Re: What exactly does Processing do?

What exactly does it do? I know that it changes the sound coming of of a speaker, but what goes on in the processes?

I'd say most simply put, it changes the voltage and phase of a signal to achieve some result.

For linear time-invariant systems this change falls into the category of a transfer function.Transfer function - Wikipedia, the free encyclopedia

I'm not an expert in signal processing, but I think many processors try to apply transfer function to a signal to "correct" it. That said, the thing we are trying to correct (loudspeakers) I don't think are completely linear in all cases. This is where other more advanced processing is necessary.

 

[Kemper Watson]

Re: What exactly does Processing do?

Uses equalization to make each bandpass as unusably coherent as possible
Sets limiters as needed
Sets delay times as needed
Sets proper x over point
Assure proper phase

 

[Ivan Beaver]

Re: What exactly does Processing do?

In a simple sense-it is used to help align all the different drivers (that are operating in different passbands) to act as a single driver.

The closer the drivers act as if they if were a single driver-the more accurate the sound will be.

That "single driver sound" is more than just the freq response. It is also the phase response. Freq is pretty easy to get flat-as long as you don't pay attention to phase and you also look at different positions in the coverage pattern 9again looking at amplitude (freq) and phase response.

One measurement position is easy. Getting the same everywhere is a bit more difficut-if not impossible with some designs.

 

[John Roberts]

Re: What exactly does Processing do?

What exactly does it do? I know that it changes the sound coming of of a speaker, but what goes on in the processes? Apologies for the dumb question, but whenever I use speakers with processing, I just 'use them' and never put in any thought of what happens. I know that sometimes EQ can be applied, among other things, but what does a processor do to the signal being processed? For example, Vertecs with V5, and Vertecs without it. What does the processing do to make the Vertecs with V5 presets make it sound so much better than the ones without it?

While I am not familiar with the vertec's specific processing in general "active speaker processing" picks up to finish where the passive design ends or runs out of options. In an ideal world passive loudspeaker designs could be made almost perfect and we'd just connect amplifiers to them. Back in the bad old days that's all we did because fancy processing did not exist as a viable option. Nowadays modern processing is relatively cheap, and even so cheap in some cases that it is preferable to fix some speakers designs in the processing, but that is not the topic.

Specifically speaker processing adresses the things we hear, so first mission is to improve frequency response to correct for driver shortcomings (too much or too little output).

Next, a variant on the first mission is to improve the way the drivers work together to deliver more accurate combined output with (very) sophisticated active crossovers.

Then active processing can compensate for, and/or enhance how cabinet design determines LF response. Active filters can combine with the passive response created by the box tuning. Output level can be traded for extended LF response, or more response higher with a sharper roll-off. Also important is added protection against very LF content that could kill unloaded drivers in ported cabinets.

Lastly sophisticated processing can dynamically tweak response based on loudness to sounds better at low level while not providing too much bass at high spl. Sophisticated processing can even anticipate driver heating and mitigate against that.

I repeat I do not know how much, if any of this is in the vertec but I am speaking of the general class of processed speaker systems, and my short list is not complete for all cases.

JR

 

[John Halliburton]

Re: What exactly does Processing do?

Nowadays modern processing is relatively cheap, and even so cheap in some cases that it is preferable to fix some speakers designs in the processing, but that is not the topic.

Although it should be...

Some more observations on digital loudspeaker processing:

The time delay adjustments available inside a speaker cabinet between drivers/sections, between cabinets in a system, and between the system and actual performers output(s) have been to me, the biggest gains. Synchronizing these has IMO, cleaned up pro audio quite a bit.

The precision with which you can set the processing also improves the consitency of the system more than the knobs on analog crossovers, comps, eqs, etc. all patched together in the chain. Less of an issue with top end gear, but that's always the case.

The threshold to aquire and use this technology really allows everyone from bands packing their own, weekend warriors, etc. to have a much better set of tools available to them for maximizing sound quality. As always, it depends on the other pieces too-the operator, the gear chosen, and the room/venue, but still...

Best regards,

John

 

[George Friedman-Jimenez]

Re: What exactly does Processing do?

Within the OP's original question, why do filters necessarily affect the phase of the waveform?

 

[Mike Brown]

Re: What exactly does Processing do?

Within the OP's original question, why do filters necessarily affect the phase of the waveform?

Check out this article: Audio Filters -- Theory and Practice

In essence, phase is the property of audio that we are actively fiddling with to CREATE filters. There is no free lunch.

There are such things in the digital realm of minimum phase and linear phase equalizers, but these have the expense of latency. FIR filters are a very nice solution to this for live applications, and are becoming very common in DSP devices for system management and powered speakers.

Check out http://lavryengineering.com/pdfs/lavry-understanding-fir-filters.pdf for more info.

 

[John Roberts]

Re: What exactly does Processing do?

Although it should be...

Some more observations on digital loudspeaker processing:

The time delay adjustments available inside a speaker cabinet between drivers/sections, between cabinets in a system, and between the system and actual performers output(s) have been to me, the biggest gains. Synchronizing these has IMO, cleaned up pro audio quite a bit.

The precision with which you can set the processing also improves the consitency of the system more than the knobs on analog crossovers, comps, eqs, etc. all patched together in the chain. Less of an issue with top end gear, but that's always the case.

The threshold to aquire and use this technology really allows everyone from bands packing their own, weekend warriors, etc. to have a much better set of tools available to them for maximizing sound quality. As always, it depends on the other pieces too-the operator, the gear chosen, and the room/venue, but still...

Best regards,

John

And worth repeating that you should be careful about running with very sharp knives (like scalpels).

Just because the end user now has access to these tools doesn't mean they should feel compelled to second guess the work output of real speaker engineers, made with complete understanding of the design, intimate knowledge about the specific driver performance metrics, and often superior measurement facilities, up to and including anechoic chambers.

To clarify, there are things that can and will change from night to night due to room, band, audience interactions. There are also things that will not change every night, like the relationship between the multiple drivers within a single box, etc. Understand the difference and be selective about what you tweak.

JR

 

[Ivan Beaver]

Re: What exactly does Processing do?

To clarify, there are things that can and will change from night to night due to room, band, audience interactions. There are also things that will not change every night, like the relationship between the multiple drivers within a single box, etc. Understand the difference and be selective about what you tweak.

JR

+100

This is one thing that EVERY sound person should read and understand.

The two are VERY different.

And an unknowledgable person could attempt to "fix" one of these-at some listening position-and really screw it up for all the others.

 

[George Friedman-Jimenez]

Re: What exactly does Processing do?

Thanks for the references, Mike. Makes sense when you think about the mechanisms by which a filter can reduce the amplitude of a waveform in a given frequency range.

 

[Ben Lagman]

Re: What exactly does Processing do?

Well that sure answered my question, thanks everybody.