Need Help using an RTA

[Jack from Indo]

The only good local installer here in Bali just lent me his RTA. It’s a PHONIC PAA2. He don’t speak English well enough to understand the manual, so he wants me to read it, then teach him how to use the thing. In return I get to use it for a few days, whoopie! Only thing is I don’t understand half the terminology! I thought I could just read the manual a bit, turn this baby on, take a reading of the 31 bands, and off we go. Ain’t so simple. So, can anybody help? To wit:

1. I get a choice of response time. Why? And which one do I want? The choices are 35ms 125ms 250ms and 1 sec. Manual is no help in explaining. Seems to me you would just want the fastest possible, no?

2. You need to pick a “weighting” setting. Huh? I get a choice of “A”, “C” and “Flat”. All calibrated according to “American National Standards Insititue”.
Reassuring, but what the hell are they talking about? Intuitively, “Flat” sounds like the right one, doh, but the manual says that “A” is the most frequently used weighting type. Well, OK., but nowhere in the manual does it tell you what the hell all this means. So what one do I want? “A”? Why?

3. It has a pink noise generator if you don’t have one yourself. But no white noise. Now waitta minute. I thought that WHITE noise is the one you want to use to get a flat frequency response, cause pink noise is skewed towards the lower frequencies, whereas white noise is flat. Right? Wrong?

Anybody help with this and you get two free beers on your next trip to Bali. And you would have helped bring ever better car audio to the small group of fanatics down here. Thanks.

[MacLeod]

1. I get a choice of response time. Why? And which one do I want? The choices are 35ms 125ms 250ms and 1 sec. Manual is no help in explaining. Seems to me you would just want the fastest possible, no?

This sounds like the time frame that the RTA takes a reading and displays it on the display. The really fast delay is sometimes hard to work with cause its changing so much.

2. You need to pick a “weighting” setting. Huh? I get a choice of “A”, “C” and “Flat”. All calibrated according to “American National Standards Insititue”.
Reassuring, but what the hell are they talking about? Intuitively, “Flat” sounds like the right one, doh, but the manual says that “A” is the most frequently used weighting type. Well, OK., but nowhere in the manual does it tell you what the hell all this means. So what one do I want? “A”? Why?

Got me on this one. Never heard of it.

May want to pop on over to Elitecaraudio.com's forum and ask there. A whole bunch of smart fellers in that place.

3. It has a pink noise generator if you don’t have one yourself. But no white noise. Now waitta minute. I thought that WHITE noise is the one you want to use to get a flat frequency response, cause pink noise is skewed towards the lower frequencies, whereas white noise is flat. Right? Wrong?

Ummm, kinda. White noise has equal energy per frequency which I suppose would make it flat but pink noise has equal energy per octave which makes it sound flat. Make sense? Cause it sure dont to me.

[Jack from Indo]

Hey thanks MacLeod. I thought of going to Elite with this but want to try here first. I been on Elite before. The Elite guys are going to write me entire technical papers and Phd. thesis's which I still won't understand, lol.

[MacLeod]

Found out the difference between the different weights.

A weighted is for more midrange frequencies like engines, freight trains whatever. It sets the mic more for stuff youll hear everyday. 300-5000 Hz therabouts.

C weighted sets the mic for all frequencies like test tones or pink noise that you would use for tuning an EQ - 20 to 20K.

[Jack from Indo]

Ok. Cool, so I guess C is the one then, although I would like to understand this better, and I wonder what the flat weighting is for?

Rereading the manual I now realize that an RTA (at least this one anyway) is not specifically made for car audio at all. They don't mention automobiles, or stereo equipment of any sort anywhere in it. It's a general tool for sound and audio technicians.

I tried to log on to elite. It accepts my password, but won't let me post. I tried emailing the site webmaster and it got returned due to "invalid address". I tried making a new account, and got a message saying "we see that this computer already has an account" and it would not let me make a new one.

[MacLeod]

Try the forum on Carsound.com

Quite a few heavyweights over there as well.