mark1101 Posted February 8, 2008 Share Posted February 8, 2008 I have another forum member's equipment and have used RTA to measure my listening room. I made many measurements from several different places in the room and the curve changes very little, and only in the LF region. I am happy with what I see I am just wondering if I made any mistakes. I calibrated both the system and mic, and used a PC with audigy 2 zs sound card. I used Pink noise and averaging as recommended in the instructions with RTA. On the curve shown the mic was at my listening position 18 feet away. Everything appears to be within almost +/- 2 db. The music sounds fine. You can see the settings I used. Did I screw something up? Quote Link to comment Share on other sites More sharing options...
jwc Posted February 8, 2008 Share Posted February 8, 2008 Hey Mark, can you run that with a small scale like only 20-30 dB? Right now there is 70dB. Quote Link to comment Share on other sites More sharing options...
Coytee Posted February 8, 2008 Share Posted February 8, 2008 Check your PM's Quote Link to comment Share on other sites More sharing options...
mark1101 Posted February 8, 2008 Author Share Posted February 8, 2008 JC I am running curves right now. I'll get that posted in a minute or two. They all come out the same. Something has to be wrong. My speakers are not flat to 20 Hz. I know that. I have been playing with individual tones and that is very interesting. I found that I can clearly hear down to about 29 Hz. and up to about 18Khz. The MWMs are inaudible to me at 20Hz. but I can feel the output. Quote Link to comment Share on other sites More sharing options...
mark1101 Posted February 8, 2008 Author Share Posted February 8, 2008 Just did this. Higher resolution. Quote Link to comment Share on other sites More sharing options...
mark1101 Posted February 8, 2008 Author Share Posted February 8, 2008 sweep Quote Link to comment Share on other sites More sharing options...
jwc Posted February 8, 2008 Share Posted February 8, 2008 Mark. Those don't look "real". The original ones you sent me were more realistic. Can you do this: Bring the frequency scale 10Hz-300Hz. Do sine samples with peak hold on. Use the "bar mode". Go 10 Hz at a time. Start at 20Hz and increment up to 300Hz. Do 10 Hz at a time. Show what that does. Don't worry about what shoes up "between the bars". jc Quote Link to comment Share on other sites More sharing options...
mark1101 Posted February 8, 2008 Author Share Posted February 8, 2008 JC, Hey man I worked all day! That's quite an assignment. Several runs. The key is averaging. If you don't average you can get some wild curves that move all over the place like I originally showed you. As the averaging happens on the screen everything slowly flattens out. I agree what I have now does not look right. I may need to do this in the morning. Tomorrow is my last shot. Quote Link to comment Share on other sites More sharing options...
jwc Posted February 8, 2008 Share Posted February 8, 2008 Sorry Mark. I didn't mean to suggest wasting your whole night...my bad. It's Friday.....drink some beer! I like Pink noise the best. Let me just tell you what settings I use. Real quick....I made this mistake before (this isn't to be condescending as I was a bonehead).....after I calibrated everything.....I realized that whenever I generated a signal...whether Pink Noise or Sine....I was getting a readout of the "Internal" signal on the computer. Meaning what was showing on the screen wasn't actually coming through the mic. I'm not sure what I was doing wrong at the time (microphone muted?) but when I figured it out...I always checked in the future by gently "tappin" on the mic to show that those taps were coming on the screen. Then I turned on the signeal generator. Here is what is "checked" under my "spectrum analyzer" . RTA mode 1/24th octave Speed trade off 80Hz Averages 100 Nothing else under that heading is checked! The rest of the settings on the software (in that mode) will just change the appearance of the readout. Hope this helps. Miller Time Dude. jc Quote Link to comment Share on other sites More sharing options...
mark1101 Posted February 9, 2008 Author Share Posted February 9, 2008 Well I was asleep by 10:00 last night. Rough week. But I thought about it last night and I agree I somehow have the generator signal being fed back into the RTA software internally on the PC and not through the mic. There's no way the system is that flat. I'll go figure out today. I'm pretty sure the issue is in the Audigy connections and mixer control. I believe I am operating the RTA correctly now. I am using a very similar setup to what you mention above. Quote Link to comment Share on other sites More sharing options...
Deang Posted February 9, 2008 Share Posted February 9, 2008 Real Time Aggravation Quote Link to comment Share on other sites More sharing options...
DrWho Posted February 9, 2008 Share Posted February 9, 2008 Hey Mark, that looks like you're measuring the output of your sound card! In your Audigy sound card configuration, you need to change the record source to the mic input instead of the "what you hear" (which sends the output of the soundcard into the recording input). The "problem" with pink noise is that it doesn't have every frequency in it at the same time....the idea is that randomly over a long period of time every frequency is hit at some point. This would explain why you have a jagged response when not using averaging and peak hold. The problem with averaging and peak hold is that more of the noisefloor and acoustics of the room end up in the measurement - and often don't correlate very well to how fast the frequency content in music changes. Nevertheless, it can give you an idea as to the relative tonal balance of the system. And the more you control your environment (like moving to an anechoic chamber or outdoors), the more informative it can be. Quote Link to comment Share on other sites More sharing options...
mark1101 Posted February 9, 2008 Author Share Posted February 9, 2008 Well, operator error found. Mike you and JC were right. The audigy mixer was set wrong and RTA was simply reading my sound card. FIxed......some curves coming up. Thanks Quote Link to comment Share on other sites More sharing options...
mark1101 Posted February 9, 2008 Author Share Posted February 9, 2008 You have to take these with a grain of salt. The very first curve I ran was the room noise and it had several peaks due to hum in the test equipment and normal noise floor of our house. I ran curves for about 5 hours. It can get tiresome. But it is one of the most valuable things I ever did to make big improvements. Knocking back the peaks in the LF made a big difference. I could not improve the HF. It is just about perfect as is. I am going to post 1 curve at my listening positon and the "correction" I made. Some of the peaks remain and were system and home noise. They were in the original curves I ran on the room. There are suckouts at around 180 and 500Hz in the corrected curve. They do not exist at other places in the room. My whole purpose for posting this is to show how peaks can get knocked back with PEQ. When you play music afterward and switch in the EQ you realize that those peaks were obscurring detail. Now the detail can be heard. Essentially a free upgrade....tuning the system to the room. It made a big difference at my house. Quote Link to comment Share on other sites More sharing options...
mark1101 Posted February 9, 2008 Author Share Posted February 9, 2008 Here is the corrected version using my Behringer outboard PEQ. Quote Link to comment Share on other sites More sharing options...
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