Graph for plotting

[moreira85]

Finally got an avia disc. Does anyone know where i can find a graph to plot the different SPL at differ frequencies?

 

[Mika75]

RealTraps Test Tone CD

A series of MP3 files you can download and burn to a CD. Our intent is not to duplicate all of the features of commercial test CDs. Therefore, we supply only low frequency sine waves, in 1 Hz increments, with a track organization that's easy to understand. We also created a blank sheet of logarithmic graph paper you can print to plot the results.

 

[Adam]

Are you just wanting to graph the data? I use Excel, but there are other software packages (like OpenOffice that is free). You can also buy/make/print out graph paper if you want to go old school with it.

 

[moreira85]

well i got the AVia II puposely for the test tone sweeps but I dont believe this disc has the differ frequencies to plot the sub freq. Any ideas?
As far as plotting on excel how do I do it?
I am familiar with excell but trying to think how to label the x and y axis.
do i just put frequencies in increments of 10 starting at about 200 down to 10on the bottom and then db going up from about 40 to 80 in increments of 5? Also when i play the tones do i just leave the volume on the reciever at about 75db and record what the spl says as the frequencies play?
sorry for all the questions but i am convinced i am in a null. When i walk around my sub within 5 feet i can really feel it, when i get the listening position it is faint. (Although I shouldnt say faint because it still sounds very earth shattering)

 

[Adam]

I have a test tone disc that I use that sweeps through various frequencies from 16Hz to over 100Hz. You can also download those tones from the internet and make your own CD. My disc also has an initial track that is pink noise that I use to set the volume level on my receiver so that I read 70dB on my SPL meter (some people use higher, some use lower). After setting the volume control on the receiver, you would keep the volume on the receiver the same and record the SPL reading on the meter for the various frequencies (like you said). For the Radio Shack SPL meters, there are correction factors for the lower frequencies that you can download - I'm not sure about the other SPL meters. Some others here are more knowledgeable about that.

In Excel, you could make two columns of data. The first column would be the frequencies of the tones (and you'd just enter the value of the frequencies). The second column would be the SPL readings for those frequencies. You can also incorporate the correction factors in Excel. When you plot the data, the X axis would be frequency and the Y axis would be measured SPL.

As an example of a plot that I made this way, you can check out the attached plot of the first post in the thread linked here.

That's just to get the ball rolling. I'll be happy to help you out more with this.

 

[GlocksRock]

I beleive you can get an excel spreadsheet along with REW (room eq wizzard) and it even has a correction table you can add in depending on your SPL meter. Just google for it, since I can't remember offhand where I got it from, but it's free.

 

[croseiv]

No test tones on the Avia II disc unfortunatley (none denoting any specific frequencies). You can use realtraps, but BE SURE TO TURN IT DOWN if you do as those tones are very loud.

 

[moreira85]

RealTraps Test Tone CD

I guess i am going to use the real traps test tones. I noticed for each frequency it says like 20-29, 30-39, 40-49. How should i label this on the X axis 25, 35, 45hz?

 

[croseiv]

Try to do 1 Hz increments if you can. 5 Hz can miss a null or peak. I know it seems rather tedious, but that is the best way. It's a great way to bond with your sub..

 

[moreira85]

Try to do 1 Hz increments if you can. 5 Hz can miss a null or peak. I know it seems rather tedious, but that is the best way. It's a great way to bond with your sub..

where am i going to find 1hz increments? that means i have to plot over 100 test tones!!!! the real traps audio file goes in increments of 10. I was just about to start doing the test when my wife turns the dishwasher on before bed. arrrrrgh! I will post results in a bit for 10 hz increments at least.

I stand corrected, Real Traps are in 1HZ increments.

 

[moreira85]

I have a test tone disc that I use that sweeps through various frequencies from 16Hz to over 100Hz. You can also download those tones from the internet and make your own CD. My disc also has an initial track that is pink noise that I use to set the volume level on my receiver so that I read 70dB on my SPL meter (some people use higher, some use lower). After setting the volume control on the receiver, you would keep the volume on the receiver the same and record the SPL reading on the meter for the various frequencies (like you said). For the Radio Shack SPL meters, there are correction factors for the lower frequencies that you can download - I'm not sure about the other SPL meters. Some others here are more knowledgeable about that.

In Excel, you could make two columns of data. The first column would be the frequencies of the tones (and you'd just enter the value of the frequencies). The second column would be the SPL readings for those frequencies. You can also incorporate the correction factors in Excel. When you plot the data, the X axis would be frequency and the Y axis would be measured SPL.

As an example of a plot that I made this way, you can check out the attached plot of the first post in the thread linked here.

That's just to get the ball rolling. I'll be happy to help you out more with this.

I do have the Rat shack meter and I set it to a range of 70, however at some frequencies it goes above 80 and it wont read it. Should I just set it at the 80 range for these then switch back to 70 when needed? Is that okay to do during a test?

 

[Adam]

I do have the Rat shack meter and I set it to a range of 70, however at some frequencies it goes above 80 and it wont read it. Should I just set it at the 80 range for these then switch back to 70 when needed? Is that okay to do during a test?

That's what I do. I'd like to hear other people's opinions, too.

 

[GO-NAD!]

No test tones on the Avia II disc unfortunatley (none denoting any specific frequencies). You can use realtraps, but BE SURE TO TURN IT DOWN if you do as those tones are very loud.

In theory, it can be used for test tones, but when you play them, it's in a steadily decreasing frequency. The manual provides a formula to calculate the frequency at a given point in time.

I say you can do it in theory, because you need three hands, four eyes and the reflexes of cat on speed to be able to observe and handle the SPL meter and stopwatch simultaneously. Plus, a black black belt in math to figure out how to use the formula...

 

[moreira85]

When doing the frequency in 1 Hz increments what frequency should I test up to? I was going to start at 20Hz, should I go to 100 or 200Hz?

 

[GO-NAD!]

When doing the frequency in 1 Hz increments what frequency should I test up to? I was going to start at 20Hz, should I go to 100 or 200Hz?

Are you just checking the sub? Or do you want to see how the sub is blending with the mains? If you're just checking the sub, what is your crossover frequency? If you're at 80 Hz, I don't see the point in checking much beyond that, say up to 100Hz? If you want to check the blending of the sub with the mains, I'd say go up a bit further.

I'm expecting a test tone CD from Rives any day now, and plan to check from20 Hz to 20 KHz, just to see where my peaks and dips are.