PC into RTA?

[Alex Lancaster]

Hi:

I would like to turn a PC into a RTA, I have seen programs advertised, but would like Your opinions about program, mike, and, I guess a sound card, I do not think the one I have (generic), would be even close; The PC is a [email protected], 1G ram, 15" Hi-res LCD monitor.

I will use it for my and friend´s curiosity.

Thanks, Alex.

[Robh3606]

Well I considered that and tried it but my PC is ancient a 200MMX so it really could not run it properly. Your PC looks like a keeper to me so you don't have that issue. Depending on the cost of the software and soundcard you might want to consider a stand alone. Granted you have a lot more utillity down the road with a PC test set-up. I use a Berhringer 8024 as an RTA it was a cheap way to get a 1/3 octave RTA. The bottom line is what ever can do what you want for the lowest cost but think ahead too. If I ever get a faster PC I would seriously looking into what measurement software is available.

Rob

[boputnam]

Hey, Alex...

Man, IMHO you just gotta go for SmaartLive 5 - Link - it's actually owned by Harman/JBL.

Anyway, it is The Standard. Pricy, but incredibly functional. You'll need some doohickys to get things running - an Earthworks reference mic (M30), and the XLR interface/preamp/phantom power, etc..

In every FOH gig I've done this is the standard. Pink noise generator, RTA, much, much, more. Click on a bar of the "spectrum mode" EQ and it tells frequency and note of the scale. Handy, handy, handy.

Ian's got a much more affordable "pedestrian priced" work-around that he's real fond of, but I've not tried it. Ian's got his head in baffles, so no telling when he'll pitch-up.

You need a duplex sound card - one that can coincidently send and receive (pink noise out, measurement data in). These are more standard in newer computers, than in the past. It's handiest on a laptop for portability (you can take it to your friend's house), but with long enough cables, you can RTA your house, surely.

So, for a no-risk set-up, this is what you'll see FOH and monitors mix, as well. It's how the pros have gone. Period.

[Alex Lancaster]

Bo:

Thanks, I saw the page, but what I want is something with a couple less zeros.

Alex.

[Oldmics]

Just a note about the ownership of Smaart. The S.I.A. Software Company who did the original design work for JBL was purchased by E.A.W. (Eastern Acoustics Works).With the release of Smaart Version 3.0 in March of 1999 all ties with JBL and Harman were broken off.Currently JBL refers Smaart updates to the S.I.A. Software site.It has become the standard in pro sound world even though I would say 98% of the owners that I have encountered only know how to turn the RTA window on with there laptops for "The Cool" look! Oldmics

[Ian Mackenzie]

Na Na Bo,

Been observing the fauna in the sun today.....

Try this link for the software called Winairr by the inventor

pcbunn.cithep.caltech.edu/jjb.html

You can buy it legally from audio express for $49.00 here

http://www.audioxpress.com/bksprods/...e/sof-airw.htm

WinAIRR is a software tool for measuring the frequency response of loudspeaker systems. It runs on a PC with Windows 95/98/NT equipped with a sound card that must feature full-duplex operation. Although WinAIRR is not a professional measurement system, useful reproducible results can be obtained with careful adjustments of the supplied controls. Version 4.02 features:
• Averaging: Time or Frequency
• Sample Record Delay
• Time Domain Cuts
• Sample Rate Adjustment
• Analysis Results: Standard, Histogram, Phase, Waterfall Full Mixer Control, Plot Scaling, Adjustment and Subtraction
• Storage of Results to Disk, and Retrieval from Disk
• Support for 48kHz sampling rate on soundcards which Version 4.02 includes Executable and software manual in HTML (Web Browser) format.
Requirements: IBM Compatible, 486+ (Pentium recommended); Windows 95/98 or Windows NT; 8Mb RAM (32 recommended); 1Mb hard disk space; sound card capable of full-duplex operation; VGA 1024x768 pixels, 16 colors. Shipping Wt: 1 lb.


After that go up to IMP or Clio, but for what you need to know this is it as far as software is concerned. Then its down to listening tests to trim the L Pads. But you will need a mic and preamp ..also available from audio express from memory

Ian

[boputnam]

Originally posted by Oldmics
I would bet 98% of the owners only know how to turn the RTA window on with there laptops for "The Cool" look!

Whew... Could be. I've seen it assist in taming some phenomenally difficult acoustics, but I tend to hang around pedantic types .

Originally posted by Ian Mackenzie
Been observing the fauna in the sun today.....

Knowing you, she's gotta have a name...?

Still mean to give that Winairr a try - I'm horribly behind on too many fronts. There's a few other PC RTA's I've used - more of the freeware stuff. Lemme check...

[boputnam]

Yea, Alex - here's another...

True Audio / TrueRTA - Link I've used this in the past, and it was pretty comprehensive. It has since been upgraded. I've not trialed the most recent version, but it's priced-right. I've not A/B this against Smaart.

Here's the screen shot of the "Bar Mode" - make it your wallpaper and you'll at least look cool!

[boputnam]

I'm not finding too much else that I recall knowing about.

Try a google on "spectrum analyzer" and other iterations, and see where you end-up...

[Alex Lancaster]

Thanks!, I contacted them about what microphone to use, and if my sound card is adequate, I kind of doubt it, it is an el cheapo; Suggestions?

It really looks good and affordable.

Alex.

[boputnam]

Originally posted by Alex Lancaster
...what microphone to use - Suggestions?

Ugh... They are all expensive. Earthworks - Link brands the best known and most acclaimed "M30", but they are pricy - much more than say, a Shure Beta SM58 (but that's only a lowly best-of-class vocal mic ).

Ol' Ian teased me with an email wherein he describes how he put-together rather inexpensively a flat-response condensor mic (Panasonic, I believe... ) and preamp confab that reportedly works terrific. That email's at home. Maybe, if he wakes early enough, he can post that before going to the dayjob...

[Oldmics]

Howdy All,Thought I would stick my two cents in here.I see a lot of PC and stand alone measurement devices being used (mostly inappropreately)in my world.I would like to address some of the things that I see which may be benefical to new users.The measurement taken with any device is only as good as the knowledge availiable to the person doing the test and limited by the hardware used in such tests.An R.T.A. adheres to standards that are routinely being ignored as more and more people get into the measurement game.Critical measurement is done in an anechoic chamber with calibrated mics.Before computers these flat referenced mics were a hughly expensive and precious items stashed away in the labs.Well we can"t put our sound system from our listening room into an anechoic chamber for measurement so that leaves us with calibrated mics in the real world.The few fine quality measurement mics that are still manufactured today are very expensive due to there quality construction and materials.B and K microphones come to mind.The current crop of relatively inexpensive measurement mics (under $1500.00 which is cheap for a measurement mic)do not have ruler flat response(and expense) of the old calibration mics.However these annomilies can be entered into the software files of the particular program that you use to compensate and correct the calibration.That is the first mistake that I commonly see made.The omission of microphone anomilie information into the files of the user program. This lack of information will skew a response curve.Measurement taken with Shure 58s always bring a chuckle to me.A great mic,not slamming the 58 but not quite right for this application.What ever mic that you decide on,make sure that you get the calibration files with it so that they can be entered into the program that you decide upon and then load those files into the program.Without a standard to hold to whats the sense in measurement anyway?Personally I like Praxis from Liberty Instruments for driver analysis.They also have a freeware R.T.A. availiable at www.libinst.com Most of these programs will have to be purchased before the microphone information can be loaded in.Good luck,Oldmics

[JonFairhurst]

This is the mic I use:

http://www.behringer.com/02_products...M8000&lang=eng

It's not ruler flat, but it sure beats a 58 for this application. (Don't try mic'ing a Marshall stack with an ECM8000 though...)

The ECM has a 2dB bump at around 7k, but if you believe the chart it's smooth enough to be factored out. Of course, they don't show the standard deviation or a file with the response of your particular serial number, but what do you want for around $35?

For RTA software I found some German shareware a couple of years ago. Can't think of the name right now, but it wasn't fully developed, and was somewhat difficult to use. I can't read German, but most of the technical terms were easy to figure out. It's nice to see that there are more RTA options these days.

For a soundcard, the M-Audio FireWire 410 would be killer. It uses 1394, so it plugs easily into a laptop - and it gets the A/Ds outside of the desktop case. It has two XLR inputs with phantom power. It also has a 108 dB S/N and supports 24-bit, 192 kHz. Plus ten outputs. It's overkill if you're not doing home studio production, but overkill can be a good thing :-)

I use an EchoAudio MIA and a Mackie 1402 VLZ-Pro mixer. The MIA uses a balanced input, so noise is kept relatively low.

And noise is the killer for RTA measurements. You may expect to see some nice smooth curve that describes your system. You won't. If you're doing sweeps, any extra noise will affect the results. And then there are room resonances and possible rattles. Make the volume high enough to overcome noise, and you may blow your drivers (and ears). Plus any mis-match in impedances or overdriven section may distort, clip or limit your result.

Reading a sweep is like reading a lie-detector test. You have to know how to interpret the results.

Finally, if you have knobs on the front of your devices, you may find things to be fleeting. Multi-turn pots inside of your crossover is much better for setting and forgetting. And in the end, you will likely wish that you had a muti-band EQ, so you can compensate for your room and all the rest.

These days I've been tuning to taste. As long as it sounds good to me, what more could I want :-)

[4313B]

"These days I've been tuning to taste. As long as it sounds good to me, what more could I want :-)"





The other stuff can be quite fun though if not taken too seriously

[Robh3606]

My favorite is setting up the 1/3 RTA and EQ's to get things looking real good. Then you run your sine sweep. Damn things lie like hell! Using pink noise they average whats there and don't excite the room resonances . Too narrow in bandwidth. But what can you do. Have to admit they are useful tools but like you say you need to tweek by ear when all is said and done.

Rob