# Help With Interpreting Graphs and Next Steps



## Nick (Oct 28, 2009)

Hello, I was wondering if someone could help me with what I should be thinking about next. I have 5 filters on my preamp that I can use per channel which I use mostly on the low end. I'm trying to have the low end 8-10 dbs higher than the frequncies after 100hz, but I can't really pull that off. 
The SPL graph below is a 1/12 smoothing. I hope no one minds that I didn't post up to 20000hz. The graph above 1000hz looks fairly flat and looks pretty standard. I'm curious if there is something I should be doing to address the slow decay showing on the graph. I have three bass traps and can add two more in the back corners.

After the waterfall graph, what should I be trying to understand next?

Thank you for any input.

Nick


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## JohnM (Apr 11, 2006)

Above 25 Hz or so there doesn't look to be anything to be concerned about in the waterfall plot. The stuff below 20 Hz (assuming it isn't external noise/interference) probably isn't of much consequence, but the only practical way to tackle it would be filtering - an effective bass trap at those frequencies wouldn't leave much space in the room for you


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## Nick (Oct 28, 2009)

Hi John, thank you for your reply. Assuming it is not external noise, should I be trying to filter out the stuff below 20hz, given it is not audible? I don’t have a sense of feeling it.

I’m wondering now if I should be trying to measure understand ‘impulse’ and how to properly measure. I don’t really have a handle about what to do try to optimize at the next level. I plan to try to find posts on what to do and how to read what the software is telling me. If you have any guidance on what you think I should be doing, I’d love to hear it. I’ve been reading about FIR filters but I’m not sure I have the right stuff for figuring all of that out. Then my mind goes to Dirac Live and the MiniDSP products. But I thought I should try some measurements to see what the level of need might be in my room. If you have thoughts on that, I would appreciate hearing them.

Thanks again,
Nick


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## JohnM (Apr 11, 2006)

I wouldn't worry about the stuff below 20 Hz, and the rest of the response as posted doesn't show anything to be concerned about either. If you post the mdat file for the measurement happy to have a look at that.


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## Nick (Oct 28, 2009)

Thank you again John. I think I just uploaded the file...


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## Nick (Oct 28, 2009)

By the way, this measurement was taken with a 0 degree orientation. I can do another at 90 degrees if that would be preferred.


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## JohnM (Apr 11, 2006)

Looks OK, though the wavelet spectrogram shows some oddities in the timing. Something like Dirac would be needed to tackle that, and perhaps some broadband absorption.


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## Nick (Oct 28, 2009)

Thank you, John. I moved the speakers and ran another test. If it is not too much to ask, I was wondering if it changed what you saw? Were you looking at the area between 200-300hz? I'm on my way to trying to find an article that explains how to read the graph you posted...


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## JohnM (Apr 11, 2006)

Looks pretty similar. It is straightforward to generate that graph, here are the settings used:


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## Nick (Oct 28, 2009)

Many thanks, John. Now I need to figure which Dirac Live product to purchase. It sounds like it might be worthwhile to put up more absorption panels, too? I have some that I took down awhile back when I switched to dipoles...


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## JohnM (Apr 11, 2006)

Certainly worth trying absorption. I wouldn't rush into buying anything based on a measurement result, try and get an in home demo of anything you are considering to see if it makes a worthwhile difference.


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