Need Help (Newbie here): Full range speakers, REW and EQ filters - Home Theater Forum and Systems - HomeTheaterShack.com

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post #1 of 13 Old 05-21-14, 03:31 PM Thread Starter
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Need Help (Newbie here): Full range speakers, REW and EQ filters

Hi!

I've read few tutorials here and there concerning REW and Digital Room Correction and most apply to subwoofers only with little to no indication concerning full range speakers.

In my case, using my UMIK-1 (one speaker at a time... and I only have two, no subwoofer) and smoothing up the graph 1/3, I've seen that there are some severe dips and peaks up to 850 hz (most of them are in the 20-250 hz range) mainly due to my room (my speakers being Polk LSiM705, so I could consider them full range 20-20000): without room correction, there is a severe emphasis on bass, some 5-6 dB peaks here and there and some dips in the midbass and midrange.

So I've measured both speakers and they seem to be similar, with some difference here and there but the overall graph is similar and with 3-5 dB of each other, at most. After, I tried to do a filter (well... let's say 10-11 filters), but it seem to apply only to a single speaker and in a such way, it won't take the other speaker when making the filter and while using the convolution engine on JRiver, it doesn't sound right at all.

So, here's my question: how do we manage to take both speakers into consideration with our filter. Do we have to "merge" the measures, and if so, how do we do that? Tutorials were silent about that... or am I mistaken?

Thanks a lot for your help!
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post #2 of 13 Old 05-21-14, 05:56 PM
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Re: Need Help (Newbie here): Full range speakers, REW and EQ filters


Just curious, what tutorials are you talking about?

Below about 3-400 Hz you can use independent filters for each of the speakers to correct response. Above that point independent filters usually do weird things to your imaging, so filters need to be matching.

Regards,
Wayne




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post #3 of 13 Old 05-22-14, 03:10 PM Thread Starter
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Re: Need Help (Newbie here): Full range speakers, REW and EQ filters

Well, I would say I watched-read a lot of tutorials here and there. There were a manual explaining in detail what to do, but nothing about "merging" both your left and right measurements or anything that could help me do something more.

As for independant filters, I think I can't do it. I use JRiver and in the convolution engine, I can insert one filter, so I guess it has to be a "common" filter to both speakers, right? Or is it possible, with REW, to create a filter that would act independantly on both speakers?

Thanks again,
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post #4 of 13 Old 05-22-14, 04:37 PM
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Re: Need Help (Newbie here): Full range speakers, REW and EQ filters


Sorry, can't help you with JRiver - I know nothing about it.

Regards,
Wayne



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post #5 of 13 Old 05-25-14, 08:37 AM
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Re: Need Help (Newbie here): Full range speakers, REW and EQ filters

I've been using JRiver for a couple years, and I use it's eq section extensively. When you try to use convolution (box is clicked and a file is loaded) what does the status say? It'll either say "Not Valid" or "Enabled and processing...etc" or something like that. You need to create the filters in REW with the same sample rate that you are using in MC. If you are using the default sample rate settings, then it could change depending on the recording....which means you need separate filters for each sample rate.

It is possible to use the convolver to create separate filters for each channel...........in this case you need to use a convolver config file which is also where you would load separate filters created for different sample rates so MC can automatically switch the filters for files of different sample rates. Here's a link that shows how to setup the config files: http://convolver.sourceforge.net/configegs.html. When you load a filter into MC's convolver without any type of config file to map it, then that filter will be applied to all channels as long as it's working correctly.

That said, for someone in your situation who is not doing any kind of FIR filtering (which can only be hosted as a convolution file) I think you ought to skip convolution altogether and directly input the parametric filters you determine in REW into MC's PEQ. When you do this you can define which channel the filter is for, and you don't need to worry about the sample rate. It's a bit more work, but the upshot is you can change individual filters on the fly without having to create an entirely new convolution file. I have 3-way active speakers + subs and I do all the channel routing, eq, and xo work in MC's PEQ.
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post #6 of 13 Old 05-27-14, 10:54 AM Thread Starter
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Re: Need Help (Newbie here): Full range speakers, REW and EQ filters

Thanks natehansen66!

Convolution was working, but as both speakers did not need the same correction, is sounded out of "place". So, after getting the list of filters, I did what you suggested (manualy entering every frequency, Q and gain in Parametric EQ) and it helped tame the bass. Sound is much cleaner now, bass is smooth but no longer overpowering. I know it would be better to treat the room as I have some crazy 12-15dB peaks in the bass region, but I guess it should suffice to give me an idea of what the speakers are truly capable of with my amp and my current room.

Thanks for the link too!
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post #7 of 13 Old 05-27-14, 05:43 PM Thread Starter
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Re: Need Help (Newbie here): Full range speakers, REW and EQ filters

Another thing, if I may.

When using full range speakers (capable of 22hz-40khz and 42hz @-3db), how am I supposed to measure bass: with both speakers running, or one speaker at a time? I'm asking that because on a tutorial on MiniDSP, they say that for let's say, under 200 hz, we should use both speakers. Should I run two measurements, one for the lower frequencies, and another for the higher frequencies?

If we need to run both speakers, how can I do that? In the preferences, I can only select one output at a time (L or R). I can't see anything about being able to run every speaker at the same time.

Also, is there any frequencies that should not be corrected (e.g. anything over 1000 hz)?

Thanks!
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post #8 of 13 Old 05-28-14, 09:27 AM
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Re: Need Help (Newbie here): Full range speakers, REW and EQ filters

Personally, I measure both speakers (and subs) at the same time below 80hz or so. To do this you need to use a loopback connection in MC. It grabs all audio sent through the Windows sound driver and routes it through MC's audio processor. When you do that you can set up some "Mute" filters in the PEQ and pick and choose what channel you want to sweep. If you need help getting the loopback going let me know.

IMO it's best to keep room eq below about 2-300hz. Above that if I feel there is correction needed I do speaker response correction using gated measurements (typically at 1m, but it really depends on the speaker configuration), on axis as well as off to see what's going on. From what I've read, our brain does a pretty good job of filtering out the room influence above the modal region, and as the wavelengths get shorter the room as less effect on the direct sound than what we see with a measurement taken with the default windowing in REW.
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post #9 of 13 Old 05-28-14, 11:41 AM
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Re: Need Help (Newbie here): Full range speakers, REW and EQ filters

Quote:
pyrocyborg wrote: View Post
Another thing, if I may.

If we need to run both speakers, how can I do that? In the preferences, I can only select one output at a time (L or R). I can't see anything about being able to run every speaker at the same time.
I've same doubt, but in my case need to run Sub+ FR and FL speaker at same time to see full graph of my Home Cinema, but I can only select one speaker to measure.

Last edited by dreamer79; 05-28-14 at 11:47 AM.
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post #10 of 13 Old 05-28-14, 12:30 PM
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Re: Need Help (Newbie here): Full range speakers, REW and EQ filters

If you are using JRiver's convolution engine, then yes you can only apply a "sum" of the left and right speakers combined. If you use the PEQ in the Parametric EQ 1 and Parametric EQ 2 you can input separate settings for each channel. I generally measure both front speakers and subs together and use the convolution engine for that. I use PEQ 1 for center and surround eqing and I add a Linkwitz Transform to my subs on PEQ 2.
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