Eq'ing your computer based system with a cellphone and a PC/MAC

[prerich]

One of the advantages of automatic EQ'ing is that you don't have to worry about creating the right filter. When using things like REW you find the rises and then apply a fliter that wil bring the rise to flat, yada yada yada. Hopefully the results will be right, and for many people the results are astounding. However some people are more visual than others - so I would like to share a "tip" on using a cellphone (or iPad) based RTA app, a calibrated mic, your PC supplying the pink noise, and your PEQ (whether it be in JRiver or Foobar vst, or a piece of hardware) to visually see the results of your filter while you are equing it.

First you will need a cellphone with a RTA app, I use AudioTool for this. Secondly - you will need a calibrated microphone - I use the Dayton iMM-6 calibrated mic which has a response that's flat to 18hz. You can purcahse this mic for $17 at parts-express. You will need to play pink noise through your PC - either via a program (there are free ones out there - REW has a tone generator) or via a CD. Finally your PEQ (hardware or software).

1. Set up your cell phone and mic (the imm-6 comes with its own cal file)

2. Start your pink noise. Look at the RTA (don't breathe or hover over the phone the mic is very sensitive - it will pick you up) note the rises and falls in the RTA. First rule - deal with peaks not dips!!!

3. Now go to your PEQ and correct for the peaks that you have. If you are using a software PEQ (like the ones in JRiver or Foobar vst) you can ajust while looking at the results of your filter actively via the RTA !!!! If you are using a hardware unit you will have to move back and forth, but you will still see the results via the RTA in real-time. This is an easy way to see the results of your filter. You can tweak it right there and see it's results (Q changes, freqs ect.) When you get the desired response - save your filter and enjoy the music!!!!

I used this technique for my entire system (JRiver gives me the option to apply seperate PEQ filters to each of my 7.1 channels) giving me an overall very flat response curve in my room!!!! I'm not saying that this will trump Audyessy, TaCT or Trinnov - but it's darned good!!!! Another suggestion is to take measurements in more than one seat. I have it where my three main seats have very flat response and pretty good imaging - my sweet spot is definately larger now. I hope this helps.

[prerich]

I will add this - since moving my Cornwalls back to the wall - I was worried about my pans - seeing that my Heresy center channel is much closer to me than the CW's. I'd already set my reference levels, then I EQ'd the system. I put on the Guardians of Gayhole because I know this movie has a lot of directional ques and pans. The pans were as smooth as silk!!!! I wanted to make a CW center channel at one time ....not now! The Heresy is holding its own (as a matter of fact - being closer with the CW's greater sensitivity has helped the situation). The pans are "perfect"!!!! Not just the ones across the screen either - front to back is just as smooth - it sounds like you are in the enviornment. I've also listened to some multi-channel BD music...Primavera on the AIX BD was just magical, they were right there with you!!!!

I'm excited about the possiblities with a HTPC and the filtering that can be applied. It can't hurt to try it - because most of its free or cost pennies compared to what we spend on audio gear!!!!

[Jim Hawkins]

Originally Posted by prerich

One of the advantages of automatic EQ'ing is that you don't have to worry about creating the right filter. When using things like REW you find the rises and then apply a fliter that wil bring the rise to flat, yada yada yada. Hopefully the results will be right, and for many people the results are astounding. However some people are more visual than others - so I would like to share a "tip" on using a cellphone (or iPad) based RTA app, a calibrated mic, your PC supplying the pink noise, and your PEQ (whether it be in JRiver or Foobar vst, or a piece of hardware) to visually see the results of your filter while you are equing it.

First you will need a cellphone with a RTA app, I use AudioTool for this. Secondly - you will need a calibrated microphone - I use the Dayton iMM-6 calibrated mic which has a response that's flat to 18hz. You can purcahse this mic for $17 at parts-express. You will need to play pink noise through your PC - either via a program (there are free ones out there - REW has a tone generator) or via a CD. Finally your PEQ (hardware or software).

1. Set up your cell phone and mic (the imm-6 comes with its own cal file)

2. Start your pink noise. Look at the RTA (don't breathe or hover over the phone the mic is very sensitive - it will pick you up) note the rises and falls in the RTA. First rule - deal with peaks not dips!!!

3. Now go to your PEQ and correct for the peaks that you have. If you are using a software PEQ (like the ones in JRiver or Foobar vst) you can ajust while looking at the results of your filter actively via the RTA !!!! If you are using a hardware unit you will have to move back and forth, but you will still see the results via the RTA in real-time. This is an easy way to see the results of your filter. You can tweak it right there and see it's results (Q changes, freqs ect.) When you get the desired response - save your filter and enjoy the music!!!!

I used this technique for my entire system (JRiver gives me the option to apply seperate PEQ filters to each of my 7.1 channels) giving me an overall very flat response curve in my room!!!! I'm not saying that this will trump Audyessy, TaCT or Trinnov - but it's darned good!!!! Another suggestion is to take measurements in more than one seat. I have it where my three main seats have very flat response and pretty good imaging - my sweet spot is definately larger now. I hope this helps.

This sounds really cool. I have only a two channel setup, this will benefit that as well?

[prerich]

Originally Posted by Jim Hawkins

This sounds really cool. I have only a two channel setup, this will benefit that as well?

Yes!!! It will work with a two channel set up as well !!! You can set the test tones for stereo 44.1k

[prerich]

Here's a measurement of my Cornwall's and subs (the purple/pink line is the sweep measurement) - the dip at around 600hz is characteristic of the Cornwall midrange horn crossover freq. This is what J River can do for your PEQ in the bass region!!!!

[avlhcm1]

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