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post #1 of 29 Old 04-28-07, 05:06 PM Thread Starter
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First graph

Hi guys!

I finally came around to getting some measurements done , I'm not really sure of what I'm doing I'm just following the help files as a trained monkey.

anyway this is my graph I have made several of them an I get the same results so I guess this is good , now I need recomendations on getting the correct filters to my BFD

TIA!



BTW:

I'm connected through my AV receiver so my front speakers where measured as well not sure if that is ok...
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post #2 of 29 Old 04-28-07, 05:38 PM
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Re: First graph

Quote:
my front speakers where measured as well not sure if that is ok
Disconnect the fronts and take a look at the sub alone.

Change the graph axis limits to a vertical scale of 45dB to 105dB and a horizontal scale of 15Hz to 200Hz and repost...

Set the target crossover to the one you're using for a reference to see how the sub looks. i.e. 80Hz

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post #3 of 29 Old 04-28-07, 06:35 PM Thread Starter
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Re: First graph

Is this better?



The axis have been corrected and the cutoff is at 80 which is how I got my crossover set up
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post #4 of 29 Old 04-28-07, 07:05 PM
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Re: First graph

I guess the mains are still operating in the above graph, since the sub doesn't show the 80Hz rolloff?

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post #5 of 29 Old 04-28-07, 07:58 PM Thread Starter
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Re: First graph

I don't get it

when you say disconect the speakers , you mean just unhook the speaker cable or should I turn them off at my av receiver

I have been making several measurments and still can't get a 80hz rolloff
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post #6 of 29 Old 04-28-07, 08:09 PM
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Re: First graph

Quote:
when you say disconect the speakers , you mean just unhook the speaker cable or should I turn them off at my av receiver
If you can shut them off at the receiver, then that's fine as long as they don't play. Put the receiver in stereo and select the mains as small and the crossover at 80Hz and then shut down the mains. Usually, when you have a receiver you have to remove the speaker cables (with the power off of course) to shut the mains off, but some receivers allow it. If you have a separate power amp for the mains, you can simply shut it off...

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post #7 of 29 Old 04-28-07, 09:39 PM Thread Starter
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Re: First graph

Last try for today

receiver is set to stereo crossover @ 80Hz the calibration has been made with REW subwoofer pink tone to 80db in order to maintain my regular listening volume



is this what I'm looking for?? or can some one post a graph of what MY graph should look like

Thanks in advance
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post #8 of 29 Old 04-28-07, 10:18 PM
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Re: First graph


That looks more like it. I’d try smoothing your graph to 1/6-octave (or whatever brucek usually recommends – I forget what it is, but I like 1/6 personally). Anyway you can experiment with some different locations? That depression below 30 Hz looks like it’s going to be a real problem.

Regards,
Wayne



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post #9 of 29 Old 04-28-07, 10:36 PM
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Re: First graph

Quote:
Id try smoothing your graph to 1/6-octave (or whatever brucek usually recommends
Well, actually we only use smoothing for full range measurements, where reflections can cause comb filtering that makes it difficult to see the underlying trend of the response. It is rarely used for low frequency measurements as it would obscure the true shape of the response and so not allow accurate correction filters to be determined.

Quote:
is this what I'm looking for??
Yep, I wanted to see if the mains were influencing the sub in that dip area around 30Hz, and they're not.
You've got about four peaks that could be equalized and would result in a much smoother result. I'm sure if you use REW to find peaks and then assign filters and play around a bit, you will reveal what the final response would look like if you used a BFD...

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post #10 of 29 Old 04-29-07, 01:28 AM
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Re: First graph

Something funny going on because your first graph shows you're getting great response all the way down to below 2Hz, unless you have a rotary woofer, there is something funky going on. And with these graphs we cant see where the natural roll off of you sub is, and since you really don't want to boost below what your sub is capable of you need to find out whats going on with the readings.

BTW what sub do you have?

cheers


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