EQ and RTA software

[subharmonic]

So I am able to find many cheap or free RTA programs for Windows but not a lot of luck finding an output EQ.

What do you guys use? I am looking in the cheap to free area.

I was thinking TrueRTA either 1/3 or 1/6 option for RTA purposes.
http://trueaudio.com/rta_abt1.htm

But I would like to be able to EQ my output from the laptop.

[Frederic Gelinas]

If you find something, let me know.

[subharmonic]

If you find something, let me know.

Hopefully it will be posted here.

[sonicanvil]

Try looking at SAC?
http://www.softwareaudioconsole.com/

[subharmonic]

Try looking at SAC?
http://www.softwareaudioconsole.com/

Yes. But for that kind of cash I think I will stick to my Driverack. SAC seems a lot more powerful but I am a DJ, I want to pink rooms, have some EQ at my fingertips, everything else is more than I need. Maybe a little parametric for feedback, but that is built into the Crown amps.

[BrentEvans]

Software that can do real time audio manipulation, and do it well, is somewhat rare. The free DAW [img]Reaper[/img] can do it... but you still really need a pro level sound card to get good quality and approach real time latency. The cheapest interfaces out there can do it, even used, are going to be several hundred dollars, and require a PCI card or a really good firewire interface (TI Chipset).

I like "RoomEQWizard" which you can download from the Home Theater Shack forum (membership is free). The newest version of it has a RTA function, as well as a swept-sine measuring function which will automatically calculate EQ points to flatten your system. You can then put those parametric points into your amp, and you'll be in good shape. You can then run a feedback destroyer or some such to get rid of the feedback...

Bear in mind that just running pink noise an looking at an analyzer while you adjust EQ is not all there is to tuning a PA. You should do that much outside, get the system flat using the tuning available in your DriveRack, and then use the analyzer in the room to find room modes and balance the sound in the room as much as possible by manipulating the location of your speakers... you can't fix a phase or modulation problem with EQ.

[subharmonic]

I got that more is better in terms of dsp. However i am just trying to see if anyone knows of an ouput eq. I can't imaging that it should be that difficuot or expensive, seems basic but it may not be. Can one replace the driverack? Maybe maybe not.

[Gregory East]

Apparently not, for the reasons Brent outlined. You need a lot of computer hardware. What about a good oldfashioned analog unit? Dime a dozen these days.

[BrentEvans]

I got that more is better in terms of dsp. However i am just trying to see if anyone knows of an ouput eq. I can't imaging that it should be that difficuot or expensive, seems basic but it may not be. Can one replace the driverack? Maybe maybe not.

There are a couple of free software packages that will do it... but the expensive and difficult part is the hardware required to make it happen. Your standard PC sound card's drivers will have something along the lines of a quarter to half a second of latency at their most capable settings. Pro hardware will have much less than that... 5-10ms.

In other words... unless you're going to invest as much as a small digital mixer in the hardware and run something like SAC, or you already have the hardware, it's just not worth it. The main benefit to a PC based LAW (Live Audio Workstation) is the enhanced and added processing over a digital mixer of the same price point.

Sorry to be the bearer of bad news, but it just isn't as simple as it seems.

[subharmonic]

I appreciate the feedback. I am trying to digest what Brent said. I looked through the manual for my DBX DriverackPx and it doesn't say anything about modulation or phase adjustments. Are we sure it does this when it pinks the room?

As for my current hardware the output interface I am usually using a NI DJ2 sound card. In a pinch I may use a Behringer UCA202, although currently that as my input. I was hoping to get a Blue Microphone Icicle, and drop the UCA202 all together as I need to bring a Behringer 802 mixed for phantom power.

Looking at the Reaper software I think we may not be on the same page. My idea was to place a mic in the dance floor and adjust the room once. But instead of doing this with a Driverack doing it with a RTA software and output EQ. I am not trying to mix live sound or vocals, maybe a filter or two for feedback but I may do that on the amps itself if possible.

Apparently not, for the reasons Brent outlined. You need a lot of computer hardware. What about a good oldfashioned analog unit? Dime a dozen these days.

I am trying to streamline my rig, not add to it. I am still having trouble wrapping my head around why an analog one is fine but EQing the sound on the way out of the source isn't.

I'm not trying to be hard headed or argumentative, I am just not getting it at this time.

[BrentEvans]

Subharmonic... there is nothing on the market right now that will let you accomplish all of your goals (at least nothing commercial or non-buggy). You can do RTA and EQ in the computer, but it is expensive and will require outboard equipment. You won't be eliminating the driverack, you'll be adding an audio interface (which might take up more room than the driverack). It is also not automatic, it requires you to understand what you're seeing and make adjustments yourself.

Since you already have the DRPX, use it to do your AutoEQ and be done with it. If you want to step up to AutoEQ AND Auto feedback elimination, go with the DriveRack PA+.

As for phase and modulation... every time you introduce an EQ change you are also introducting a phase change. Your ears don't hear phase, they hear amplitude, so you must make sure your system is in phase with itself (using all the same cabinets in the same passband in the same soundfield) so you don't have modulation problems. Modulation problems also can be created by the room (room modes) and you'll never be able to fix those with EQ.

BTW... you don't "pink a room." If you set up the mic at several different places and take different measurements, you'll get different results. You need to take your system out to a field somewhere and set it up, then let the AutoEQ do its thing. Establish that baseline as a preset in your Driverack. Then, learn how to adjust the EQ manually[img]by%20ear[/img] in each room to get the sound you want. You have to use your ears to find out if its harsh, or if there are room modes or phasing issues. This is a much better method of system tuning than setting up the mic and letting the magic box do its thing every time.

[subharmonic]

The plans was/is to setup the EQ for the speakers on the XTIs (using the reverse SPL method then measuring in a field next spring/summer) and then let the driverack do its thing for the room. I never set it and forget it, I still go listen and adjust to taste (it usually sets the subs too low and the highs to hard).

But now I am wondering what the point of the driverack is, I bought it to EQ the rooms I was in. That's what it is advertised to do. Did I completely miss the boat on auto EQ? From what I understand you said it sound like it is not needed for room eq after the speakers have been EQ'd and I have been doing it all backwards. I may not be pro-audio savy but this conclusion seems wrong, in the home theater world EQing a room makes all the difference a good speaker does.

This phase issue leads me to a new question. If you can't hear it, whats the point of correcting it?

Before we get too far off topic.
Does anyone know of a EQ software that you run on your computer? Not auto EQ, just a plain ol' 31 band graphic, light program.

Thanks.

[BrentEvans]

The plans was/is to setup the EQ for the speakers on the XTIs (using the reverse SPL method then measuring in a field next spring/summer) and then let the driverack do its thing for the room. I never set it and forget it, I still go listen and adjust to taste (it usually sets the subs too low and the highs to hard).

That's a good method. Just remember that you should take several readings around the room AND use your ears to determine final EQ tweaks in a room.

But now I am wondering what the point of the driverack is, I bought it to EQ the rooms I was in. That's what it is advertised to do. Did I completely miss the boat on auto EQ? From what I understand you said it sound like it is not needed for room eq after the speakers have been EQ'd and I have been doing it all backwards. I may not be pro-audio savy but this conclusion seems wrong, in the home theater world EQing a room makes all the difference a good speaker does.

First, You don't "EQ a room," you EQ a sound system. Rooms generate problems that can't be removed by EQ, and you must realize that. This is why having the system flat BEFORE going into the room is important for quick setup... when you play pink noise through your system, you know it's being reproduced correctly, and what shows up on the analyzer are room problems that you must then deal with one by one.

The Auto-EQ functions are aimed at people who don't know how to tune a sound system, and they work pretty well at that, but you still have to use your ears, which it sounds like you're doing.

This phase issue leads me to a new question. If you can't hear it, whats the point of correcting it?

You'd hear if a phase issue causes a modulation problem resulting in loss or gain of amplitude. You can't correct phase or modulation with EQ... they must be corrected with loudspeaker placement.

Before we get too far off topic.
Does anyone know of a EQ software that you run on your computer? Not auto EQ, just a plain ol' 31 band graphic, light program.

My friend, this doesn't exist in the capacity that you want. It sounds like you're looking for a program to modify the output from your program before it gets out of the computer. This isn't how PC based sound works. Each application accesses the sound card driver (or the windows sound drivers) directly, and there is no intermediary. There is a program out there called "Virtual Audio Cable" which allows you to do some rerouting, but it's very buggy. Also, the latency induced by doing all this typically makes it unusable for live work. The other option is to introduce another sound interface and take another trip back through the computer, but the added complexity isn't worth it.

The other option is to see if your source program allows VST or DX plugins... then you could add a free 31 band EQ plug.. but this only EQs the output of your PC, nothing else.

I use PC based digital audio on a regular basis.... what you're trying to do isn't the best way, or even a good way, to do this. Use the hardware you have... you have everything you need. Eliminating one rack unit of hardware isn't going to make or break your setup.

[subharmonic]

Brent, thank you for your time and patience. Okay I think we are almost on the same page.

The other option is to see if your source program allows VST or DX plugins... then you could add a free 31 band EQ plug.. but this only EQs the output of your PC, nothing else.

I guess this is what I am looking for, just asked the wrong questions. Do you know the name of these free VSTs? I am trying to avoid buggy/spyware ones. You pretty much talked me out of trying to drop the driverack but I would still like to play with an EQ.

Since we have been discussing this, does the Driverack series do anything with phase or time issues? Seems the Audessy does time corrections and such (still leaves the bass lacking but usually has great results for dialog).

As for Auto EQ, yes I am still new to tuning a room or pinking or whatever you want to call it, I am getting better with every one I do. I usually do it cause my setup time is over 2 hours so if I can let the "magic" box do its thing then that is time saved. Put the mic in scientifically best spot on the dance floor and away we go.

So ideally you would hit 3-5 spots across the dance floor. Do a sweep or is pink better? Then average the results, implement, listen to the room, the tweak to taste. Is this the method you would use?

[BrentEvans]

I guess this is what I am looking for, just asked the wrong questions. Do you know the name of these free VSTs? I am trying to avoid buggy/spyware ones. You pretty much talked me out of trying to drop the driverack but I would still like to play with an EQ.

IF your source program allows VSTs, you might want to try ReaEQ, from www.reaper.fm. You download the entire ReaPlugs package, and it's in there. However... this is a big if. Most programs don't allow this. Winamp does, but the support is buggy. Also, every extra layer of digital processing you add in the computer is going to degrade your sound, and using more than one EQ can have some undesirable effects. Proceed with extreme caution.

Since we have been discussing this, does the Driverack series do anything with phase or time issues? Seems the Audessy does time corrections and such (still leaves the bass lacking but usually has great results for dialog).

I believe the PX does not do anything with delay, the PA and up do. Phase and time are very much related, but the relationship is variable based on frequency and distance. You really should read up on exactly what phase is. There is really no such thing as a "phase corrector." Phase problems can come from many sources... but mainly from the system not being time aligned at the crossover points, and from sound arriving at different time intervals from things like multiple mics and from bounceback in the room. Phase and time are about distance, not amplitude. EQs only correct amplitude, but they do so at the expense of phase, because changing the amplitude of a frequency band affects its phase relationship. There are some specialized software EQs which are linear phase, but they require latency in order to operate, so you can't use them in a live environment... they're studio/mastering software.

As for Auto EQ, yes I am still new to tuning a room or pinking or whatever you want to call it, I am getting better with every one I do. I usually do it cause my setup time is over 2 hours so if I can let the "magic" box do its thing then that is time saved. Put the mic in scientifically best spot on the dance floor and away we go.

The only problem is that you can't possibly know the "scientifically best spot" unless you model the room, and then it all changes when you introduce people, which are great diffusers. This is why you get the system response flat first, then use your ears to tweak... and this is an ongoing process throughout the event. This also means you MUST protect your ears... they will go into a midrange protect mode after extended exposure to high levels. Otherwise, you have to rely on hardware to tell you what's going on, which is even more equipment to set up.

Functionally... for the type of things most of us do, getting the system flat outdoors and then working with placement and perhaps minor tweaking of EQ at each venue is the best formula.

So ideally you would hit 3-5 spots across the dance floor. Do a sweep or is pink better? Then average the results, implement, listen to the room, the tweak to taste. Is this the method you would use?

Well, almost. You're looking for patterns. My personal method is to play a track I'm familiar with and walk the room listening for bass modes. If the room has high RT60 (an echo chamber) I will sometimes do this with pink noise (this takes practice). When I get the system in a place that I feel has the most even response, I then put the mic in the best place to my ears, and look at an analyzer, and adjust response as must as possible, taking care not to make drastic changes from my baseline. I then go back and listen to a track, and make any futher adjustments by ear.

That said, the adjustments I am doing by ear, you can do with your AutoEQ, once you have a baseline measurement and EQ, and you have the system placed right. If correcting through placement isn't a possibility, then you just have to walk and listen for the place that represents the majority of the room. For instance, if there's a mode you can hear, either cancellation or sum, keep the mic out of that mode.