# TrueRTA Calibration Tutorial



## ErinH

Quoting this from another site that has been posted here before but has probably been lost in the craziness the past few months...

Original Thread:
http://www.avsforum.com/avs-vb/showthread.php?t=572477




Ilkka said:


> Since HTSpot transferred this quide into section where you have to be a paid member to get in, I decided to copy it here. Hope you'll all enjoy!
> 
> TrueRTA is a nice and small RTA-program (Real Time Analyzer) made by John Murphy. The free demo of the program can be downloaded from *here*. Unfortunately the demo is quite limited so you can't really use it efficiently. To make the most of it, you need to purchase an upgrade. True Audio offers four different upgrade levels from 1 to 4. I definitely recommend level 4, because this way you get the full 1/24 octave resolution, which is almost a MUST, especially if you are planning to some EQ'ing with BFD or similar. Level 4 retails $99.95, but it's all worth it. If you absolutely can't make it, take level 3, it comes with 1/6 octave resolution. *Here* is a little proof why 1/24 is recommended.
> 
> Before anything, read the help files/topics, they are very helpful.
> 
> The program itself is very small (~1.4MB installed), but the project files are around 10MB each, so make sure you have atleast that much of free space on that drive.
> 
> *1. What do we need?*
> 
> -Computer/laptop equipped with a decent soundcard.
> -Microphone (and preamp if needed).
> -Some RCA cables between them.
> 
> Minimum System Requirements:
> A 500 MHz Pentium III class PC with 64MB RAM running
> Windows 98/ME/NT/ 2000/XP
> 
> Most modern soundcards will work just fine, for example almost any Soundblaster (Live, Audigy, Aydigy2 etc.) is fine. Soundcard must have line in and line-out connections. If you have some expensive soundcard, it will most probably work. Integrated soundcards like nVIDIA Soundstorm will work, but they are more difficult to calibrate, you need to set the input/output levels very carefully with them. I haven't yet seen a laptop with a decent soundcard. Most of them won't work. Use a USB or PCMCIA soundcards with laptops. For example M-Audio MobilePre USB is great. They retail around $100 - $150.
> 
> You can use the Radio Shack SPL meter as a microphone, but its accurancy is not very good. You can find few compensation charts for it, but none of them is perfect for your meter. They are just estimates. You can download the correction file from *here*. *NOTE: Check the end of this post, more info about RS.* Save it as a text file along your other correction files (in "TrueRTA/Mic calibration files" folder). Frequency response of the RS meter limits up to around 10kHz (even with correction file). With the correction file it is reasonably accurate down to 15-16Hz. I personally have the older analog model, but the newer analog will work just fine. The digital version does not need any corrections when connceted from the output jack.
> 
> Much better choice is a Behringer ECM8000 microphone and a Behringer UB802 preamp/phamtom power. It's basically very flat even without any corrections, but *here* is a correction file for it too. Don't use the file that comes with TrueRTA. This better file is actually property of Edward Mullen (perfect for his mic), so everyone who's using this file, remember to thank Ed!
> 
> *2. Calibration*
> 
> First you have to make a simple loop from line out to line-in using the normal RCA cables and proper 1/8" connectors. You can just connect the other channel (use left) or both. Before you start the program, check your soundcard settings. Enter by double-clicking the speaker icon on the lower right corner of your desktop (if you can't see this, enter through control panel). In playback side all sliders except wave/mp3 and master volume should be muted. If you can't see the line-in slider, enable it through options/properties and mute it. This is crucial if you don't want to have some nasty microphone feedback. In recording side select line-in, if you can mute the others, do it. With most soundcards you can set all slider at full. If you have the nVIDIA Soundstream, set line-in slider at about 1/4. Now you can start the program itself.
> 
> By default the program is monitoring only the left channel, normally you don't have to change this. Now enter the "Audio I/O" menu and check that both sampling frequencies are set to 48 kHz. If your soundcard doesn't support these, use something lower for example 41 kHz. Now using the same menu, start "Sound System Calibration". Follow the instructions and you should see two lines on your screen. First a line something like this.
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> After a second or two the line should straighten up.
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> If the first line is not completely straight, lower the sliders like we learned before. If there is no line at all, check the connections. If you can't have a straight line, your soundcard is propably very cheap and will not work.
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> Now you can load the mic calibration file. Enter the same menu and "Open a mic calibration file". Select the correct file and open it. The range will throw you out, but use the buttons on the right side to make it readable (use around 0 dB - 120 db range). Now you should see a line like this.
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> The absolute level (SPL's) might not be the same as in my picture. If you can't see the SPL readings, push down the SPL button. *Notice that if you want to do the sound system calibration again, you have to unload the mic calibration file before doing it.*
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> *3. Connections*
> 
> Unhook the loop at first.
> 
> If you have the RS meter: RS meter has an analog output using a single female RCA connector. Connect this into the line-in of your soundcard. Use proper adapter if needed. Connect both left and right channels from line out into your stereo system (usually pre/pro/amp). Use AUX/CD or similar analog inputs. Set your RS meter to C-weighting (very important, though some sources claim that output is not weighted, I will research this matter) and fast (actually fast or slow doesn't matter). Use the 80dB range. Make sure you have a fresh battery. Place the meter on a tripod or similar and point it towards the speakers. Place the tripod at the listening point (sweet spot, ear level).
> 
> If you have the ECM8000 or similar: You need an XLR cable (male/female) between the mic and the mixer. Mixer also supports 1/4" jack. Mixer output is either normal RCA or 1/4" jack. Check that microphone control knobs are near center, phantom ON, Main Mix around center. Output can be either Main Out, Ctrl Room Out or Tape Out.
> 
> *4. Settings*
> 
> When you have all the nessecary connections ready, we can look at some of the settings.
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> This is the start screen of the TrueRTA. You can use either pink noise or quick sweep (QS) for measuring. If you have a proper mic, both ways will give very similar results. With RS meter the QS can be a little bit inaccurate at the lower end of the spectrum. The pink noise is more reliable, but also much slower.
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> Normally you should have the "L IN", "MIC CAL" and "SPL" buttons pushed down. "RTA Resolution" as high as you have purchased. "Speed Tradeoff" 20Hz. Averages 1. "Input/output sampling frequency" should be set to 48 kHz, if your soundcard supports them. Use lower if not. "CPU speed setting" anywhere you like.
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> *5. Measuring*
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> Select the "Pink N" from the left (Wave). Push the green "GO" button and you should see a wavering line like this.
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> That is some backround noise of your room and also the noise from the whole measuring line. The lower the better. Now set averages 100 and the line should settle down. Averaging means that the program takes every 100th, or what ever number you have set, sample into account. John Murphy suggest a value over 1000, but I think it's too much. If you are using QS, averaging doesn't affect at all. Now you can push the Generator ON. Adjust the volume from your pre/pro/receiver so that the meter reads around 75 dB - 80 dB. It sounds quite loud, but it's not dangerous. Keep the noise running around 5-10 s so that the line settles down. Now you should see a line something like this.
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> You can adjust the range if you want a closer look. This one is also smoothed, you can find the smooth option from the utilities menu.
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> *6. Advanced features*
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> TrueRTA has an option to calibrate the absolute SPL level. Play for example 100Hz or higher sine wave (but below 500 Hz) and check the reading on your meter. You can play the tone using the built-in generator or you can use a cd/dvd. Have the program measuring all the time (GO button down) and enter Audio I/O / SPL Calibration menu and enter the SPL reading. Now the program is calibrated and it's showing absolute SPL's (=real). Notice that if you are playing a pink noise or similar wide band signal, you can see the real SPL level by pushing the dB button down. The line itself is at much lower level (~50 dB), but this is just because the nature of the signal. If you are measuring pure sine waves, the absolute level can be seen straight from the line itself.
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> Quick Sweep is a much quicker way, but I've noticed that sometimes the RS meter gives false readings especially at the lower end, since the sweep is so damn quick. You can make the sweep "slower" (actually it just sweeps narrower range) by lowering the input sampling frequency. I suggest 22.05kHz. If you set it too low (8kHz), your computer will slow down significantly. Pink noise is the "safe way".
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> You can also use Avia/DVE or similar disc for measuring. Find a suitable sweep (do not use single sine waves) and remember to have "PEAK HOLD" pushed down. Start the analyzator (GO) and start the sweep. Stop the analyzator (STOP) after the sweep and you should have the line on your screen.
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> Another cool feature is the Oscilloscope mode. You can easily check for example if your calibration signal is clipping or not. It's quite easy to use. Just have the signal running using the built-in generator and push the GO button (remember that you have to have the loop again). Adjust the range if you can't properly see the shape of the signal. Now you can set your levels very accurately. Just add the level (input/output sliders and Ampl. level) until the signal clips. Then back off by few dB until the signal doesn't clip anymore.
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> Here you can see a perfect waveform of a 1kHz signal.
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> Here you can see the same signal, but now it's clipping heavily.
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> *7. Quick recap*
> 
> -Make a loop
> -Run sound system calibration (adjust levels)
> -Load the mic calibration file
> -Connect the cables, line out -> receiver and mic -> line-in
> -Calibrate absolute SPL if needed
> -Measure your FR using either pink noise or QS
> 
> *Copyright Ilkka Rissanen*
> -------------------------------------------------------------------
> 
> I must have forgotten something or maybe you didn't understand something. Please, post questions and I will make a small Q&A list out of them.
> 
> -------------------------------------------------------------------
> *Radio Shack SPL meter info:*
> 
> Today I got my professionally calibrated microphone. Even without any correction files, it's only 0.5 dB off at 10 Hz. Pretty impressive. It was calibrated against B&K 4133 microphone.
> 
> I have now measured it against my analog RS meter. As I have said, the RCA output jack is weighted (C or A). But as Ethan showed, it appears that the output of the RCA jack of the digital RS meter is unweighted when set to C-weighting, when set to A, it's A-weighted. When set to C, it has a flat FR atleast down to 20 Hz.
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> Here is a TrueRTA screen of my results.
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> As you can see, even with those general CFs, the RS meter is still below the true FR. It tracks the mic down to 40 Hz, but below that it's off. You need to compensate even more than for example 7.5 dB @ 20 Hz. Around 11.5 dB seems to be more closer. Of course every RS is different, so this might not apply to your RS. Although me and my friends have measured total of three RS meters (analog) and they all give pretty similar FR.
> 
> http://personal.inet.fi/private/ilkka/RS_calibrated.txt
> 
> Here is a calibration file which turns my RS into calibrated measurement microphone. When using this file its FR is within 1 dB (10 Hz - 200 Hz) from my calibrated microphone. It may not be as perfect with your RS, but much better than the general CFs. Notice that general CFs are way off below 15 Hz.
> 
> *Analog version:*
> Use atleast general CFs or this file when measuring with the TrueRTA or smilar. Same thing if you are measuring manually (looking at the needle). You can use the rough corrections below, if you don't want to check the file (if you are measuring manually, add those corrections, do not subtract them).
> 
> Frequency / Correction
> 10 Hz	+5 dB
> 12 Hz	+6 dB
> 16 Hz	+14.8 dB
> 20 Hz	+11.5 dB
> 25 Hz	+7.8 dB
> 30 Hz	+5 dB
> 40 Hz	+3.2 dB
> 50 Hz	+2 dB
> 80 Hz	+1 dB
> 100 Hz	+1.2 dB
> 
> *Digital:*
> Do not use any correction files when measuring with TrueRTA or similar. The output of the RCA jack is unweighted when set to C-weighting. When measuring manually, add corrections shown above to the readings.


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## tcguy85

i still don't understand how to ACTUALLY calibrate my laptops soundcard. what exactly do i do?


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## manina

I think I was the one who posted the link some time ago 

@tcguy85 - your soundcard must have a line in (aka microphone symbol) and a line out (aka the headphone symbol). 

Both are stereo although you only need the left channel for the calibration. This is not affecting, at all, how you should proceed

1) You need a cable with two 3.5mm jacks (one at each end).
2) plug one jack in the line out
3) plug the other jack in the line in
4) set the sound level as described in the link posted
5) run the calibration

You are done.


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## borgs

Whats the price for this beauty?


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## tcguy85

manina said:


> I think I was the one who posted the link some time ago
> 
> @tcguy85 - your soundcard must have a line in (aka microphone symbol) and a line out (aka the headphone symbol).
> 
> Both are stereo although you only need the left channel for the calibration. This is not affecting, at all, how you should proceed
> 
> 1) You need a cable with two 3.5mm jacks (one at each end).
> 2) plug one jack in the line out
> 3) plug the other jack in the line in
> 4) set the sound level as described in the link posted
> 5) run the calibration
> 
> You are done.


ah, ok. cool.


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## goodstuff

I'm using the mic mate usb connector. Should I do this? I thought it didn't go through the soundcard if it was usb?


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## manina

goodstuff said:


> I'm using the mic mate usb connector. Should I do this? I thought it didn't go through the soundcard if it was usb?


Actually, an external soundcard is better the internal ones, especially in the laptops. 

So, an USB powered external card is OK - that's what I'm using as the laptop one is very cheap


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## ErinH

I went ahead and calibrated my m-audio mobilepre.


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## hc_TK

i cant get my calibrated. is it right that the soundcard is going to clip? the red clipping light light up if i use any higher than 1/4 line out and the mic level on 1/4..


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## Amish

I'm interested in checking out TrueRTA, I'd like to know what people do for inputs though.

What headunits do people have and how are they connecting the soundcard to them? I tried using RoomEQ Wizard through the Ai-net on my Alpine 9833, had some funky issues with feedback and distortion though. It didn't operate like a normal "in."


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## DanMan

I am by no means an expert,as I have just begun to experiment with TrueRTA,but I think most set up a microphone at the driver head position for input.I see that the Home audio people seem to use rca's for the means of connection,directly to their gear.


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## lyttleviet

This guy I know has one and is willing to let me use it... This is now something definitely to consider.


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## braves6117

I'm having trouble with this calibration. When I enter TrueRTA Level 2, the option "Sound System Calibration" is not available..(as in light grey as oppossed to the dark grey indicating available).

Im guessing I'm not setting this up right for my MobilePre USB...

Could someone correct where I am wrong...I think my muting is all wrong...



I have connected a two sided 1/8 jack from the Headphone output on the MobilePre front, to the 1/8 jack in the mobilepre rear titled "stereo mic."

Next, for the muting of things, the only options I have to mute are as follows:

For Playback Tab: Speakers and Line1/2
For Recording Tab: Microphone (which says not plugged in) and Line 1/2

(I could also mute Input gain, Monitor Mix, and Output Volume via another control panel too.....should I be???)

So what do I mute? 

Sorry for the dumass questions, but this setup has been sitting here, and between it and the new tutorial for gain setting via BikinPunk (awesome btw), I want to learn how!


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## ErinH

man... i'd almost have to have the laptop in front of me... jump on the chat and i'll see if i can help you.


Did you see this in the linked thread:


Ilkka said:


> *Pictures of the connections* (text/pictures property of Floyd Pierce) Thanks Floyd!
> 
> Note that I'm using a laptop so the Mic symbol would equate to line in with a normal sound card and the headphone symbol would equate to line out.
> 
> The loop connection for sound system calibration: (loop is just a stereo mini straight through)


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## hc_TK

there is no calibration in level 2.. you need level 3!


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## ErinH

whoa!!!! didn't know that!


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## braves6117

BikinPunk Rocks!


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## TrickyDIck

manina said:


> Actually, an external soundcard is better the internal ones, especially in the laptops.
> 
> So, an USB powered external card is OK - that's what I'm using as the laptop one is very cheap


Could you revist your answer on this. I think the usb mic mate is a device which allows you to plug a microphone into a USB port, and has no interaction with the sound card at all. If using a microphone such as this, why would there be a need to calibrate a sound card?

TD


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## rekd0514

True many people purchased the Micmate after the other thread so most need to figure this out using it.


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## ErinH

I think the micmate is just to give phantom power to the mic.

I don't think the micmate is a preamp of any sort.


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## goodstuff

bikinpunk said:


> I think the micmate is just to give phantom power to the mic.
> 
> I don't think the micmate is a preamp of any sort.


http://www.mxlmics.com/condenser_mic/micMate/micMate.htm

I never could get this figured out. I couldn't get a flat response or any thing close to an accurate mesurement. Tried lots of different softwares that were impossible to figure out. My 360.2 is out for repair right now but when it comes back I'd really like to get into eq'ing. Could someone write a tutorial using the mic mate and room eq wizard or a better one for true rta?


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## ErinH

On the audio setup (bottom right of the screen, right-click the speaker, then go to “adjust audio properties”, then click the ‘audio’ tab)…

Do you have the ‘sound playback’ set for the laptop’s sound card, and the ‘sound recording’ set for the microphone’?


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## TrickyDIck

Tried to use TRUE RTA tonight.

Not sure what the heck I was doing.

I fiddled around a lot. printed a bunch of graphs, twiddled some more. Drank some beer, repeated steps 1-3...

Generated a smoothed curve, modified the EQ settings, and couldn't repeat the effort. Bagged it for the night, and had another beer, and wrote up this message.

Here was my penultimate smoothed Freq response curve. See attached.

Questions.

1. there are 20 memory slots on the program. If you run RTA and save, the single smoothed 1/6 Octave graph looked best, the rest seemed too un-real as if there was too much detail to be accurate. (peaks and valleys on graph too close and difference too much to be realistic - the averaged/smoothed corves look more "realistic". Is this the correct way to do RTA for tuning (using smoothed or averaged data)?

2. I was not sure which of the check marks to select under the RTA section. (there are 3 and all can be toggled independently - RTA bar mode, Relative Mode, and SPL mode.) Not sure what the "right" way to set them is.

3. input selection. Again here is a confusing thing. Many threads talk about using the MicMate and the Behringer ECM8000 which is what I've got. There is apparently NO interaction with the sound card whatsoever. The Micmate get registered as a USB audio device. Is it necessary to "calibrate" the micmate, and since it lacks the traditional input and output of a sound card, how to accomplish? Very confusing when you follow the threads and are new to this hobby.

4. Input selection L, R, L-R, L+R? WTF?

5. Input and output sampling frequency. I used 48khz. What's best?

6. Averaging? again WTF?

7. when playing pink noise through the head unit, is it best to optimize each speaker individually or all at once? My H701 allows Front & Rear Left and right + sub controls. I started with L+R not the individual L/R controls. Also, since I have a 3-way setup, there is only a single front control which for my setup would control the tweeter and the midrange both, while the rear channel controls the midbass.

8. After a few hours at piddling around, I was able to get a crappy looking curve with lots of peaks and valleys. I used the graphic EQ option, and got:

large peaks at 32,85, 375 Hz, with many smaller peaks (12 peaks total on the graph)
large valleys at 48, 315, 1437 with similar smaller valleys.

The biggest offenders weer already gained at the max + or - 9 dB.

Overall, on my scale which I think used the dBu (whatever that's supposed to be) value, the highest peak was at 85 (smoothed/averaged) -28 dBu. The lowest valley was at 1437 at -33.5 dBu.

Here is a graph I finagled into a SPL curve....

Comments? Feedback?

TD


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## TrickyDIck

Anybody.... Anybody....

Bueller.... Bueller....


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## TrickyDIck

Seems I once again answer my own post....

Done with tht RTA tuning. Sounds really good to my ear. Fairly flat, as close as I can get with this equipment (better than the last post). 

Since I'm "done" with the stuff - at least for now, I may end up selling the equipment since its doubtful I'll ever use it again.

TD


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## ErinH

I advise against selling it. You're never done.


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## TrickyDIck

bikinpunk said:


> I advise against selling it. You're never done.


Hmm...

I think you're right....

ears practically bleeding today... I think I need to readjust the tweeters... I think above 10k, probably don't want a flat curve if you like to listen loud.

Here are my "final" curves. Well after that I tweaked the gains a tiny bit on the tweets.. yellow one if the left/driver's side, purple is the passenger/right side. Yellow curve is a little "smoother"

TD


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## ErinH

put it at 1/3dB resolution. Also, play the system. Note the changes that take place once both sides are playing together.


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## TrickyDIck

bikinpunk said:


> put it at 1/3dB resolution. Also, play the system. Note the changes that take place once both sides are playing together.


I'll try that.

Problem I am having now is balancing the system. Seems like at lower volumes (the kind that doesn't induce permanent hearing loss), the bass is underpowered. When I crank it up, the bass is there, but the tweeters become dominating. I turned down the tweeter gains and that helped this part of the problem.

Darn recordings are all over the board too, which doesn't help.

Thought about turning down the x-over gains and save them to the presets on the H701. One could be for more bass, one for less bass, and one in the middle or more balanced. I think the BASS COMP could basically accomplish the same thing, but it doesn't seem to. In order to do this, I'd have to turn down the other speakers and leave the mid-bass at +0dB since I don't think you can add +db in the crossover of the H701.

I could also crank up the midbass gains, but I think the speakers are going to hit their mechanical limits, before the amps peak out.

Any advice?

TD


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## ErinH

TrickyDIck said:


> Problem I am having now is balancing the system. Seems like at lower volumes (the kind that doesn't induce permanent hearing loss), the bass is underpowered. When I crank it up, the bass is there, but the tweeters become dominating. I turned down the tweeter gains and that helped this part of the problem.


Take a look at this thread. It talks about exactly what you're complaining about. 
http://www.diymobileaudio.com/forum/showthread.php?t=49556&highlight=loudness+curve



TrickyDIck said:


> Thought about turning down the x-over gains and save them to the presets on the H701. One could be for more bass, one for less bass, and one in the middle or more balanced. I think the BASS COMP could basically accomplish the same thing, but it doesn't seem to. In order to do this, I'd have to turn down the other speakers and leave the mid-bass at +0dB since I don't think you can add +db in the crossover of the H701.
> 
> I could also crank up the midbass gains, but I think the speakers are going to hit their mechanical limits, before the amps peak out.
> 
> Any advice?
> 
> TD


That's not a bad idea. I do something similar, but I only have a couple settings; one for regular music and one for when I want to rock out. That setting has the sub crossed higher and at a higher level.


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## TrickyDIck

bikinpunk said:


> Take a look at this thread. It talks about exactly what you're complaining about.
> http://www.diymobileaudio.com/forum/showthread.php?t=49556&highlight=loudness+curve
> 
> 
> 
> That's not a bad idea. I do something similar, but I only have a couple settings; one for regular music and one for when I want to rock out. That setting has the sub crossed higher and at a higher level.




Is there an easy way to tune with A-weighting on TrueRTA? I don't think the program has any built in features to allow this. 

I thought that a mic correction file could probably do the trick though?

TD


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## ErinH

with trueRTA, not that I know of. I believe it's C-weighted by default and I've searched around, but have had no luck with being able to find a way to change it.

A mic correction file wouldn't really work, I don't think. It might be that the weighting varies with the level, too. If you calibrate, I'm thinking you'd be baselining the measurements and would always keep that curve (essentially).


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## TrickyDIck

bikinpunk said:


> with trueRTA, not that I know of. I believe it's C-weighted by default and I've searched around, but have had no luck with being able to find a way to change it.
> 
> A mic correction file wouldn't really work, I don't think. It might be that the weighting varies with the level, too. If you calibrate, I'm thinking you'd be baselining the measurements and would always keep that curve (essentially).


So is there a way to do A-weighted levelling then? Obviously need to go back and read your post.

You used SmaartLive I think (PMed you about this).

TD


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## ErinH

yea, smaart has a & c weighting. At least, the v6 does. Not sure about v5. 

sorry about the pm. I'm extremely busy with work lately. even doing some work right now. 

I'll shoot you my # tomorrow (remind me to) and you can call me if you want.


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## handy

anyone know how to use impulse wave to tune delay setting?


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## TrickyDIck

Smaartlive 5 can do A weighting plus C, X and Inverted X. 

What the heck are X and inverted x??

PLan to save my current EQ as a no weighting (with True RTA), then try A weighting, and C weighting curves (with SmaartLive RTA). 

Can tell you at high volumes, my current EQ leaves my ears bleeding. Either I don't have it turned up loud enough to equalize the frequencies to the C weighting spec, or I am going deaf. I think there may be NO weighting to the True RTA.

I should mention, that I made my curves for True RTA withe deck at 15 volume. Maybe I should crank it up???


As an aside, still have a ground loop noise problem...



TD


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## 86mr2

handy said:


> anyone know how to use impulse wave to tune delay setting?


The thread is even on the same page of this sub-forum.

Tuning your car using a pc based measurement setup


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## TrickyDIck

86mr2 said:


> The thread is even on the same page of this sub-forum.
> 
> Tuning your car using a pc based measurement setup


I think I must be missing the boat here.


I put in a CD that has a pink noise track and put it on repeat mode. I've already positioned a mic in the listening position with cord runnning outside car. I sit outside and run the RTA program on a laptop.


From what Ive been reading, it seems like there MUST be a way that the PC is connected to their Head unit? I've got the W505/H701 and not sure how I'd do this.

ITs got to be something very obvious that I must be overlooking - conneting the sound card line-out to an aux-in for example?

TD


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## ErinH

You have to use the program's generator and send the signal through your h/u and out through your system via the aux input on the h/u. you have to have a feedback setup, too. otherwise, there's nothing to reference itself to. Basically, loop your input/output. Instructions are on the first page of this thread, I'm pretty sure.


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## TrickyDIck

bikinpunk said:


> You have to use the program's generator and send the signal through your h/u and out through your system via the aux input on the h/u. you have to have a feedback setup, too. otherwise, there's nothing to reference itself to. Basically, loop your input/output. Instructions are on the first page of this thread, I'm pretty sure.


Yeah - 
I tried making a loop-back circuit on my Vaio laptop (circa 2005) Hooked a 1/8" stereo mini plug to RCA into anothter similar cable connected with some barrel connectors to end up with a male - male 1/8" stereo mini-plug. Then I wiring Mic In to Headphones out. I know its not the same as line in and line out, but its all I've got. (At least until the M Audio Mobile Pre arrives - which appears to have both line in and line out, and also have 0 latency ... anyone want a good deal on a micMate?)

Could you refine this for me? Am I supposed to run BOTH a loop-back circuit from Line out -> Line in, as well as Line out -> HU Aux-In? This would require some Y-Splitters (I already have a mini-stereo splitter)? Its seeming this is what you've said. (attached photo of this steup)

So I tried following the recommendations for auto cal the line in and line out on the TrueRTA, but for the headphones/mic connectors, its not ideal. clipped waveforms like crazy on the OScope... I adjusted the volume settings in the windows control panel until there was no clipping then ran the autocal again. I must say I am a little bit leery about feeding this laptop headphone out into my Aux-In on the HU. I think I'll wait until the Moblie Pre comes in.

Also got WINMLS so I can follow along on the the other RTA thread. Seems like True RTA can do all the same stuff though.

I also think that I am going to use the A-weighting on Smaartlive v5.4 to re-tune (even though Chad in another thread advises against it, the car just doesn't sound right - too little low end). I may end up taking my existing EQ settings and average them with the re-tune EQ settings I get with the A-weighting, then saving these different settings into the H701 and see if I notice a difference with different listening levels. Incidentally, the Bass Comp feature on the H701 might accomplish the same thing as tuning to A-weighted-ness? Not sure, It does make for a nice way to compensate for recordings made with lower bass levels though..

TD


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## TrickyDIck

Well,

I tried calibrating my notebook soundcard. Hopeless. Going to wait till the Mobile Pre comes in to do any more. Just running the O-scope with a sine wave output and moving the mouse causes RFI on the trace. Tried running the system cal several times, and quick sweep curve looks like playing a game of artillery on one of those old PET computers -far from flat.

TD


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## handy

TrickyDIck said:


> Well,
> 
> I tried calibrating my notebook soundcard. Hopeless. Going to wait till the Mobile Pre comes in to do any more. Just running the O-scope with a sine wave output and moving the mouse causes RFI on the trace. Tried running the system cal several times, and quick sweep curve looks like playing a game of artillery on one of those old PET computers -far from flat.
> 
> TD


many of notebook soundcard is good, my internal soundcard is very flat. better not to calibrate your notebook soundcard.
first time use True Rta i use the callibrate one but the measurement is never been accurate, i use clio and lms to compare with the true and my notebook soundcard.
this it the picture of notebook, just use loop without any calibrate 

my notebook audio in/out









looping mic and headphone out









loop aux and headphone out









i use averege 10, speed trade fast, all calibration off.

but you better use external devices cause more accurates and more reliable than internal one.
i use BB-measurement for mic and the soundcard.
http://bb-measurement.tripod.com/


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## benthe8track

I hate bringing things back from the dead but wasn't sure that this deserved its own thread. Did anyone ever figure out how to get TrueRTA to show A-weighted curves? Looks like out of the box readings are linear not C-weighted. It's not complicated to apply the corrections just tedious.


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## saMxp

Isn't pink noise basically a-weighted already? White noise is flat.


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## benthe8track

saMxp said:


> Isn't pink noise basically a-weighted already? White noise is flat.


No not really. Pink noise just falls off at 3db per octave, while A-weighting follows more of a contour.


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## saMxp

benthe8track said:


> No not really. Pink noise just falls off at 3db per octave, while A-weighting follows more of a contour.


Oh ok, I always thought they were pretty close, except for the high end. I generally use pink noise and eq it flat and like what I hear.


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## Megalomaniac

bikinpunk said:


> You have to use the program's generator and send the signal through your h/u and out through your system via the aux input on the h/u. you have to have a feedback setup, too. otherwise, there's nothing to reference itself to. Basically, loop your input/output. Instructions are on the first page of this thread, I'm pretty sure.


ahh this is the part I overlooked. So if you dont have an AUX port on your deck you are SOL?


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## benthe8track

Megalomaniac said:


> ahh this is the part I overlooked. So if you dont have an AUX port on your deck you are SOL?


You can just burn pink noise onto a cd and play it from there.


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## Megalomaniac

benthe8track said:


> You can just burn pink noise onto a cd and play it from there.


But doesnt it need a reference point? Thats why it needs to be looped?


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## dmazyn

Found this on the TrueRTA FAQ:

"*Do I need to calibrate TrueRTA with the voltmeter if all I am using it for is the audio analyzer?* 
No. You only need to calibrate it if you are going to make voltage measurements where the absolute voltage or dBu level must be known. If you are only interested in relative measurements like "there is a peak of +6.25 dB at 500 Hz compared to the rest of the response" then voltage calibration is irrelevant. 
If you do not calibrate TrueRTA then the actual Line-In and Line-Out levels will be unknown. When you set the generator output level to -10 dBu the actual output level may be considerably higher or lower. Similarly, an input signal that reads -10 dBu may actually be higher or lower in level."
​


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## jets88

]Hi I just bought an m-audio mobile pre and I'm unsure about how to calibrate the thing to work with the trurta software. I'll be using the behringer mike connected to one of the xlr inputs. It's hooked up to an acer aspire one via a usb cable. I searched but couldn't find an answer. I haven't tried to hook it up yet because I haven't bought any cables yet and I'd rather not spend the money on any cables I don't need. Any help would be appreciated. Thanks


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## radioflyer97

I started usin TrueRTA when i got me PXA H701. This was the first tuning i did. Of course I've since tinkered with the SPX 17MB midbass settings so i'll have to re-tune from scratch later in the week.


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## sonyslave

I stumbled onto DIYMA last night. And this thread is pretty cool! Nice to read so many intelligent posts in a single thread.

I realzie that rta is probably being used to measure setup for competition, just wanted to throw in my .02. Ears are pretty subjective things, different people hear the same sounds a little differently (just as color perception to the eye is very subjective and some people see color (or not) differently than others. Factor in hearing loss due to high spl exposure and that further complicates things.

Using measurement tools to get flat response is great, but don't forget to tune for your own listening tools, your ears! A audibly pleasing setup is not always a sonically accurate one.

A tip: I would recommend monitoring your mic while doing measurements. Use a quality set of headphones to make sure the mic is "hearing" things accurately. The typical gear is not immune from extraneous RF noise (like cellphone emmissions, radio towers etc). If that stuff creeps into the signal while doing a measurement it could throw off your graph.


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## avences

something weird happened to me last night that i was doing test, I have the behringer Mic (the one that recomend) and a mic mate.

I run the program and the room where i was staying it was in silence, but the rta read some noise, for the level of the noise measured i thought it was like a bad ground in one cable so i started to unplugged everything one piece at time.

I took out the mic.....and the graphic didnt went to 0 it kept almost the same with no mic!!! so i was like...what the heck? then i unplugged the micmate, the graphic showed and dissapeared...then showed again but with a minimal amount then dissapear...i though well....it is done....i was looking at the screen and suddenly the sound appeared in the graphic again....something is buzzing i guessed.

Then i realised that the internal fan of the laptop was working.......there was no mic attached....can it interfiere with the measures?


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## goodstuff

Bringing this one back from the dead. Finally got going on this. Got the software working. Calibrated the sound card. Loaded the better beringer mic correction file. Using uncorrelated pink noise test disc I attempted to take measurements with all speakers playing at once. I guess I should I be playing them one at a time? Now from rereading I guess I need to run the signal (pink noise) from true rta into the aux input of the deck and then measure with the mic. Also the loop back needs to be connected at the same time? Also noticing the shortcomings of the drz eq, mainly no independent eq for hi /mid /low. On a side note the cpu I was using started repeatedly crashing after I took some measurements. I tried swaping a bunch of hardware around, thought it was memory, os virus, harddrive, videocard. Turned out to be the resolution was too high, even though it ran fine and looked fine for a while. Had me stumped. Discuss


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## captainobvious

goodstuff said:


> Bringing this one back from the dead. Finally got going on this. Got the software working. Calibrated the sound card. Loaded the better beringer mic correction file. Using uncorrelated pink noise test disc I attempted to take measurements with all speakers playing at once. I guess I should I be playing them one at a time? Now from rereading I guess I need to run the signal (pink noise) from true rta into the aux input of the deck and then measure with the mic. Also the loop back needs to be connected at the same time? Also noticing the shortcomings of the drz eq, mainly no independent eq for hi /mid /low. On a side note the cpu I was using started repeatedly crashing after I took some measurements. I tried swaping a bunch of hardware around, thought it was memory, os virus, harddrive, videocard. Turned out to be the resolution was too high, even though it ran fine and looked fine for a while. Had me stumped. Discuss



When i hear about this "loop back" it doesnt make sense to connect the laptop input to its output with a cable IF you are using a micmate. Think about this...you will never USE the mic/aux input on the laptop as your input is coming directly from the usb/micmate. So I think you are correct. Sounds like we (I say we because I just picked up the same setup) need to:
1. Connect the micmate to the usb port.
2. Connect the laptop headphone output to the rca/aux input on the Head Unit.

Now the True RTA program should be able to send its signal through your head unit and be able to record it with the mic/micmate.

My problem is that Im seeing a 40db peak fom 5K on up when just trying the pink noise out of the laptop speakers and recorded through the micmate. Its pretty flat from 20hz on up to 5K but then its a massive hump from 5K-20K. I unplugged my mic from the micmate. All output drops across the board, but theres still a big hump shown from 5K-20K. 
I figured it might be room noise, but doesnt make sense for it to be that loud and it really doesnt make sense to see it when the mic is disconnected 

Ideas ?


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## captainobvious

Hmm...odd. Must be something with my laptop. Tried it on my other laptop and it is nice and flat. Time to take some in car measurments and see what happens.


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## stereo_luver

If anybody is done with using this set-up let me know. I might want to give it a shot too.


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## ratso1

way back on page one, braves6117 asked a question that was never answered. i have the same question - can anyone help me? i also emailed this to trueRTA but never received a response. i think it has to do with the fact that right clicking on the volume control gives a different response with vista than older systems (or maybe it's just with dell laptops)? anyways to quote what i sent to trueRTA:

when i right click on the sound icon in vista, i get 4 choices: either to choose the mixer, playback, recording devices or sound. sound is obviously not right and neither (i think) is the mixer. if i choose either playback or recording it opens a three tab window. under playback i get speakers/headphone, independent headphones and line 1//2 mobilepre. i can enable and disable these but no "mute". i have all "enabled" and the preusb has a green check next to it. is this correct? under recording i have internal mic (disabled), microphone line/in (currently unavailable), rec playback (working) and the preusb (working, green checkmark). again is all this correct? sorry to be so specific, just wanted to make sure i'm telling you everything.


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## thazy2

Hello gents.


Would a Youtube video of how to be out of the questions. I see it for everything els...


curious......


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## goodstuff

captainobvious said:


> Hmm...odd. Must be something with my laptop. Tried it on my other laptop and it is nice and flat. Time to take some in car measurments and see what happens.


Missed this. What happened? I was going to suggest different cable or soundcard but I guess different computer works just as well.


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## ErinH

alright, I'll try to do a tutorial on using TrueRTA in the next few weeks.
Frankly, it's very easy to use as long as you have the appropriate gear (mic, good soundcard of some sort, and software). 

So, what do you guys want to know? Try to be specific if you can. I'll do my best to write up a short tutorial soon.j


Actually, check out this thread:
http://www.diymobileaudio.com/forum...our-car-using-pc-based-measurement-setup.html

This has some good info on using the RTA. But, again, if fellas are having an issue with using the software itself, then I'll be glad to write short tutorial on getting started with TrueRTA sometime in the next week or two.


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## ratso1

bikinpunk said:


> On the audio setup (bottom right of the screen, right-click the speaker, then go to “adjust audio properties”, then click the ‘audio’ tab)…
> 
> Do you have the ‘sound playback’ set for the laptop’s sound card, and the ‘sound recording’ set for the microphone’?


your suggestion about re-doing the setup guide is a good one, i was really surprised by how bad the 'rta for dummies' thread is. no offense to the creator who put a lot of work into it. but rta themselves seems to be using it as their main manual and emailing them gave me no answers either. i think what is confusing to me is i don't get any of the above options when i right click my volume control. i take it it's different for vista 64? or is it just the built in soundcard for my dell? what i get is listed a couple of posts above and i'm still not sure how to set it?


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## jbholsters

Why would you need to use the pink noise generator in the software? That makes no sense at all. The software is just reading spl at frequencies. If the pink noise track on your CD was correctly made, it should work fine. Tell me why I am wrong.


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## ErinH

it's easier to generate and pause (stop) the pink noise from the laptop than it is to reach inside the car and pause it.

ie: convenience.


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## jbholsters

IC, I just run it until the battery goes dead. That stops is too.


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## ErinH

you need to get a bigger battery, mang!


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## less

Thanks for this info folks. I've had my collection of RTA goodies for a couple weeks now but am only now getting the chance to play with it some. I really wish I'd just dropped a few more buck and went for the Maudio usb instead of going with the mic mate - because most everyone here is using the M-audio or a similar device. 

I've got a good selection of software in addition to TRUERTA - including synrta - winmls - ARTA and others, and I am interested in trying some of the things NPD did in his thread that is linked above - such as using impulse tests to time align perfectly... but for some reason I can't get winmls to give me a machine number so I can register for the trial period. Are there other software programs out there that allow for this type of testing? I've been using discs instead of the built in generator, but I wonder if using the generator, the timing could be synced and the timing could be checked using TRUE>

Also - I'd like to learn about gated testing and impulse testing. IF anyone runs into particularly informative posts (the For Dummies level is probably about right for me lol - but I'll brave higher order info too), please link'em up!

Thanks again. Erin, I appreciate your taking the time to share this stuff... I know its easier just to do it on your own and shut up!

Jim


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## jets88

ratso1 said:


> your suggestion about re-doing the setup guide is a good one, i was really surprised by how bad the 'rta for dummies' thread is. no offense to the creator who put a lot of work into it. but rta themselves seems to be using it as their main manual and emailing them gave me no answers either. i think what is confusing to me is i don't get any of the above options when i right click my volume control. i take it it's different for vista 64? or is it just the built in soundcard for my dell? what i get is listed a couple of posts above and i'm still not sure how to set it?


i just setup truerta on my vista 64 bit computer yesterday. rightclicking the speaker icon will give you 4 options. All of them except open volume mixer will open the same box. i only played with it for about a half hour and this is what I did. I set the mobile pre as default in both the recording and playback boxes. I first looped chanell one to itself and turned the volume knob on the mobile pre up untill I got the clipping light on and then backed off untill it went off. It's funny I couldn't get a flat line that way on channel one.

I then tried channel 2 and looped the channels to themselves and set the volume untill right before it clipped and it worked. I got a flat line. I kept the settings in the volume controller the same, mobile pre default, I can't remember where I set the volume in the recording and playback windows now but I know I used either 1/2 or full volume. i'm not sure why channel 1 didn't work either. Just remember to switch the mike input if you switch channels on the mobile pre.i'm gonna play with it more on the weekend and see if I can get channel 1 working. Also remember to use the right channel on truerta if you use channel 2 on the mobile pre. Hopefully this helps.


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## jbholsters

OK, so I am trying to calibrate this thing. I have a moble pre. I hooked up a 1/4" jack from 2/R in the output section and ran it to ch2 inst/line on the input section.









Is this right so far?

In the original post is says:
"In playback side all sliders except wave/mp3 and master volume should be muted. If you can't see the line-in slider, enable it through options/properties and mute it. This is crucial if you don't want to have some nasty microphone feedback. In recording side select line-in, if you can mute the others, do it."

Slide all sliders where? To max volume?
If I check the mute box in Master (mine says speakers) it is a "mute all" button.


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## leorbolato

Great, thanks...


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## Lars Ulriched

I got Beringger mic to do this but dont have the usb sounds card and been looking for the M audio card but unable to find it here.....can anyone tell me if I can use this instead Sound Blaster X-Fi Surround 5.1?


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## jets88

Lars Ulriched said:


> I got Beringger mic to do this but dont have the usb sounds card and been looking for the M audio card but unable to find it here.....can anyone tell me if I can use this instead Sound Blaster X-Fi Surround 5.1?


It looks like it should work. It has 1/8 " jacks so make sure you have the right cables to calibrate. You'll aslo need a XLR to 1/8" converter for the mic. I've only used the mobile pre so I can't be positive it'll work but give it a try and let us know how it works out.


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## thazy2

Anyone of you Pro's or semi-Pro's care to make a YT video for us dummies? We just cant figure it out. If you need expense money, i can help.....


I think the video will help many Newbies...............................





thanks.


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## OBXTINTWORX

i am trying to use TrueRta as an SPL meter.
I have the DBX Rta Mic and a micmate.
i can't get any reading over 122db!
The three cars i tested all should hit louder than 122.
any input is appreciated.


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## John L. Murphy

OBXTINTWORX said:


> i am trying to use TrueRta as an SPL meter.
> I have the DBX Rta Mic and a micmate.
> i can't get any reading over 122db!
> The three cars i tested all should hit louder than 122.
> any input is appreciated.


Have you performed an SPL calibration? You will need an external SPL reference for this, such as an SPL calibrator or a SPL meter. After calibration TrueRTA should match an "A" weighted SPL meter at 1kHz (only). TrueRTA's SPL measurements are unweighted and indicate the level of the entire audio spectrum. "A" weighted measurements are relatively insensitive to the bass range. In general, with music program material TrueRTA should read higher than an "A" weighted SPL meter.

Regards,

John


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## ErinH

^ FINALLY....

John, can you tell me if TrueRTA is c-weighted or non-weighted?

It seems that when I compared it against results gained in smaart, that it was c-weighted but I can't recall. Been wondering this for a while. The manual doesn't say anything about it.

Also, is there a way to add more colors to the 'memory' spectrum? When comparing 5+ results you get redundant colors which can make results a bit hard to discern without going to the memory bar and clicking one of the results off at a time to figure out which is which.


Thanks in advance.


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## John L. Murphy

bikinpunk said:


> ^ FINALLY....
> 
> John, can you tell me if TrueRTA is c-weighted or non-weighted?
> 
> It seems that when I compared it against results gained in smaart, that it was c-weighted but I can't recall. Been wondering this for a while. The manual doesn't say anything about it.
> 
> Also, is there a way to add more colors to the 'memory' spectrum? When comparing 5+ results you get redundant colors which can make results a bit hard to discern without going to the memory bar and clicking one of the results off at a time to figure out which is which.
> 
> 
> Thanks in advance.



TrueRTA measures non-weighted SPL. Unlike "A" and "C" weighted measurements (where the bass is reduced) 20 Hz has the same weight as 1 kHz.

I'll note your request for more colors for memories but that is a tough one. 

Regards,

John


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## ErinH

Thanks for the reply. Really go information to know.

Maybe it might be something to include in a future revised manual? Since it doesn't say, it's probably assumed by most that it's not weighted, but it might be worth while to put it in there so there's no doubt.


Thanks for passing the request along.


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## goodstuff

Ok. I made it through the calibration and figured out how to run the tests.
Maybe I'm expecting the wrong things from this.
I want to run a measurement, while it's measuring adjust the eq and see the change happen in real time, is this possible? 
When I try to do this the line of the graph doesn't really move at all, 
example: max boost or cut any given freq and I see little or no change on the graph. I played with speed, avg, and other adjustments but it won't respond the way I want it to or think it should.


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## ErinH

are you sure your processor allows for real time adjustments? I would assume the 9255 does.

If so, then something else is wrong in your measurement system. TrueRTA will give you real time data. I've only had issues when I've had the wrong audio source selected (ie: onboard audio instead of mobile pre)


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## goodstuff

bikinpunk said:


> are you sure your processor allows for real time adjustments? I would assume the 9255 does.
> 
> If so, then something else is wrong in your measurement system. TrueRTA will give you real time data. I've only had issues when I've had the wrong audio source selected (ie: onboard audio instead of mobile pre)



I was trying it out using my home stereo with simple bass and treble knobs. I couldn't get the line to respond to ANY changes.


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## ErinH

Did you check the sound card settings?


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## goodstuff

bikinpunk said:


> Did you check the sound card settings?


I think so? :blush: I muted all sliders except for master and wave I think. I just followed whatever it said to do. What else should I be checking? I'm thinking maybe I had the mic input connected wrong. When measuring I had the mic connected to the preamp, preamp up about half way and had the output from the soundcard going into my receiver. I thought this was correct because I used the same input/output scheme when I calibrated everything and it worked/


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## ErinH

What audio record/playback device is selecyed? Is it correct? 

You can also try restarting the program. I've had issues with disconnecting the mobilepre and it not allowing me to record again upon reconnection.


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## goodstuff

bikinpunk said:


> What audio record/playback device is selecyed? Is it correct?
> 
> You can also try restarting the program. I've had issues with disconnecting the mobilepre and it not allowing me to record again upon reconnection.


Hmmm...I'm almost positive I checked the record settings...that might be what it is. I'm at work, damn I wanna go home and try this now. I will let you know how I make out tonight. If I get it to work be prepared for my next round of stupidity, reading fr graphs. 

I've got the m audio buddy, I sold the mic mate.


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## bkjay

edit


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## willPS

As far as the dude with the acer and the ghost sounds (the fact RTA continued to register noise after he unplugged the mic), I'm fairly certain this is because once the mic was unplugged, the laptop mic kicked in and continued to run. I had an acer which did this also, somehow it played the computer fan noise and was a nuisance.

So the behringer is $50, but could I use the omni on my H2 Zoom recorder? It has a tripod mount  Or would this be inadequate/off? Picture alpine type S speakers as the quality benchmark.

Finally, quick noob question, this whole process is essentially manually doing what the Imprint does pseudo-automatically?


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## basshead

To mobilepre user

How did you calibrate your system, i only have a stereo 1/8 cord so I did it from the Stereo Line (1/8) to Stereo Mic (1/8) but when i connect the Mic it's still getting lots of noise... 

should i get a 1/4 to XLR patch to calibrate?


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## basshead

ok got it, i got a 1/4M to 1/4M cable and it worked like a charm. Also I needed to set the Mic gain to 9 O'Clock, too high the signal was clipping.


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## John L. Murphy

Hello TrueRTA users! This is to announce that TrueRTA version 3.5.0 has been released and is available for download at trueaudio.com. Here is a link to the download page: TrueRTA Audio Spectrum Analyzer Download Page

The new version is Windows 7 compatible and allows selection of audio devices from within the software. Quick Sweep now operates reliably at all signal levels. Many small improvements and bug fixes have been made.

Regards,

John


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## basshead

Thanks John for the update.

just installed the new version on my 7 and i get distorted signal from the generator (most notable in the pink noise), anyone else experience this problem? With the previous version it was fine (same win7 install, i just upgraded truerta), the soundcard is a maudio mobilepre but get the same distorted signal from the onboard soundcard.


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