# First Graphs...



## Matteo (Jul 12, 2006)

Allright,
I have calibrated and measured and I think I have this almost under control. I am going to post my graphs to make sure everything is looking alright. The first picture is my soundcard calibration with my mic cal (I think that is the to line). The second graph is my left channel response, the third is my right channel reponse, and the last is my left channel response with the impulse response controls. Not sure what the last graph is supposed to look like. Everytime I applied the Impulse Response Control and set the pre ref to 125, my graph turned into a bunch of very close vertical lines. I will let you respond to this before I ask any more questions. Curious if the soundcard looks okay and how bad the response graphs are? Also, it doesn't matter if I run the left or right channel measurement, all four subs fire. Is that weird?
Roly


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## brucek (Apr 11, 2006)

> The first picture is my soundcard calibration with my mic cal (I think that is the to line)


I don't really understand this statement, but the soundcard cal in the first graph looks perfect except for the squiggly line I've highlighted. I have no idea what that is. Hopefully you saved the soundcard file.










You show 5 graphs. The first is the soundcard response. I take it the second graph is with the soundcard loopback in place and you're checking for a flat response to verify the soundcard calibration went correct.

You've lost me on the next two graphs that you call left and right channel? It is the sub you're measuring? 
I do remember you had a stereo 2500 power amp driving your 4 IB's. You split the signal from the BFD and fed both channels. If that's the case then the sub out of your receiver is a mono signal that you check as one channel. All 4 IB's will play in concert.
Select the SUB tab and do the response - no LEFT and RIGHT.

Remember to reset your GRAPH AXIS LIMITS each time you measure to return to the default settings. The axis is incorrect on your left and right graphs.



> Everytime I applied the Impulse Response Control and set the pre ref to 125, my graph turned into a bunch of very close vertical lines.


Yes, but that's the Impulse graph - you now need to return to your response graph. Select View and return to Filtered Adjustment screen where your graph is shown..
You don't need to provide the Impulse response graph. Once you take a measurement simply set the window to 125ms and return to your graph and that's it.

brucek


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## JohnM (Apr 11, 2006)

There's definitely something wrong with the mic cal curve, maybe attach a copy of the mic cal file and we can see what is going wrong with it.


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## brucek (Apr 11, 2006)

Yikes, perhaps that squiggly line is Rolys ecm8000 calibration file. Not good, for sure.

If so, you have corrupted the file somehow. If you had your ecm8000 professionally calibrated, then reload the file (and perhaps post it here so we can see it as John says).

You should read THIS thread that Sonnie posted and perhaps download his ecm8000 calibration file that he has provided there...

brucek


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## Matteo (Jul 12, 2006)

Hello,
Yes, that squiggly line is my mic cal. I just reinsterted the cal files and came up with the same thing. Here is a paste of the cal file. 
As far as the left and right measurements go, just to the right of the SPL on the REW are two tab circles listed as right and left. One of them is checked at all times. Is this not supposed to be this way? It looks built into the program.
10	2	0
15	2	0
20	2	0
25	2	0
30	2	0
35	3.08	0
40	2.5	0
45	2.5	0
50	2.5	0
55	2.5	0
60	2.5	0
65	2.5	0
70	2.5	0
75	2.4	0
80	2.3	0
85	2.3	0
90	2.4	0
95	2.4	0
100	2.4	0
150	2.5	0
200	2.4	0
250	2	0
300	1.7	0
350	1.7	0
400	1.5	0
450	1.3	0
500	1	0
550	1	0
600	1	0
650	0.9	0
700	0.9	0
750	0.8	0
800	0.6	0
850	0.4	0
900	0.4	0
950	0.4	0
1000	0.4	0
1500	0	0
2000	0	0
2500	0.4	0
3000	-0.4	0
3500	-1	0
4000	1.2	0
4500	0.8	0
5000	0	0
5500	1	0
6000	1.6	0
6500	1	0
7000	-0.3	0
7500	0	0
8000	0.3	0
8500	-0.8	0
9000	0	0
9500	0.3	0
10000	0	0
11000	1	0
12000	1	0
13000	0	0
14000	0	0
15000	1	0
16000	0.8	0
17000	0.6	0
18000	0.4	0
19000	0.4	0
20000	0	0
21000	1	0
22000	2	0



Thanks

Roly


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## brucek (Apr 11, 2006)

> Here is a paste of the cal file


Yeah, I see the problem - that file is nuts. The file is providing frequency/level/phase without proper decimal points (where did you get this file) and seems to be quite crazy. A microphone just doesn't have that form of reponse.
You should use Sonnies file here and I feel it will provide a better representation of your mic - see how smooth it is in his thread on the subject.. Save it as your mic.cal file



> As far as the left and right measurements go, just to the right of the SPL on the REW are two tab circles listed as right and left. One of them is checked at all times. Is this not supposed to be this way? It looks built into the program.


As I said, simply use the SUB tab and do your measurement for the 4 speakers. 

brucek


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## Matteo (Jul 12, 2006)

I got that file from two different sources, most recently at AVS forum. I am glad you have discovered a problem. It gives me hope. I will paste a new pic to make sure the new file looks alright. As far as the axis, I set them to L 15, R 200, Top 105, bottom 45. Correct? So I don't do that once, but everytime I measure? Also, does it matter if I apply that before or after the reading? Thanks a ton. I am on my way to measure again.
Roly


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## brucek (Apr 11, 2006)

> So I don't do that once, but everytime I measure?


Yes, the axis limits are only preserved as long as the most recent measurement you have taken are *inside the graph axis limits* of the setting. No big deal - just look at the graph, and if it's not at the values you have set in the axis limits, then make it so.



> got that file from two different sources, most recently at AVS forum.


Oh my gawd. AVS? , are you serious ? !!!!!!........ Use Sonnies file and you'll be fine...

brucek


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## Matteo (Jul 12, 2006)

Oh wow,
Just did another measurement. The first graph is listening position, the second is near field. Not much difference. Is this an indication that my sub sucks? I sure don't have much SPL under 30Hz. 
Roly


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## brucek (Apr 11, 2006)

OK again!!!!!, you don't have the Graph Axis Limits correct!!!!!, so change that so I can properly evaluate.

Did you use Sonnies mic.cal file ?

brucek


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## Matteo (Jul 12, 2006)

Yes, I did use Sonnie's file and I posted a graph of it a few threads ago. The mic cal response is the flat line that jumps at about 5k Hz as you move right. I guess I am not getting the Graph Axis thing. I just reset it and will try another graph. If it doesn't work, you can shoot me, please.


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## brucek (Apr 11, 2006)

> If it doesn't work, you can shoot me, please.


Hehehehe, good one Roly...

OK, that graph has the correct vertical and horizontal axis. Good job - now we can evaluate. :T 

As you say, it is a bit challenged in the bottom end. It drops off rather quickly below 30Hz, which is not what you would expect from a 4 driver IB.

I was wondering about your hookup in regard to your 2500 power amp? Have you seen this thread from Chrisbee who has the same equipment basically?

brucek


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## Matteo (Jul 12, 2006)

I am on my way to that thread right now. Just out of curiousity I meausured a 10" Polk and an Earthquake 12" MKIV. Now I know they are not all calibrated, so what I did was to use my SPL and change the volume on each sub until the SPL read 80. That way the subs volume was at the same level as my 4 subs. Then I ran each test seperately. Not sure if that even works, but the response is interesting. All the graphs are very similar. The Polk and Earthquake are powered, both Xovers at 80. Could it be something in my hookup that isn't allowing me more output? First is Earthquake, then Polk, then mine.
Roly


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## brucek (Apr 11, 2006)

> so what I did was to use my SPL and change the volume on each sub until the SPL read 80. That way the subs volume was at the same level as my 4 subs. Then I ran each test seperately. Not sure if that even works, but the response is interesting.


Now you're getting it........ good job..



> Could it be something in my hookup that isn't allowing me more output? First is Earthquake, then Polk, then mine.


I don't think it's your hookup. It seems correct. The room determines a lot of what happens...

The Earthquake looks the best for sure. Look at that Chrisbee thread I referenced on the 2500 hookup and try again...

brucek


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## Matteo (Jul 12, 2006)

Perhaps a solution. Reading the 2500 amp manual, I notice some dip switches on the back. Currently I have the low cut filter set to 50Hz. It has a 30 Hz option, which the manual says is better for subwoofers, but I can also just shut off the low cut filter. I think this may be the big problem. Looking at my graph it plummets, right at the 50 Hz range. If I disengage the filter, it states that "frequencies below 5 Hz are cut to prevent damage." So should I try the 30 and see what happens, or just turn the **** thing off?
Roly


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## brucek (Apr 11, 2006)

> Currently I have the low cut filter set to 50Hz. It has a 30 Hz option, which the manual says is better for subwoofers, but I can also just shut off the low cut filter. I think this may be the big problem.


For sure.......................... shut the **** low cut off.....


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## Matteo (Jul 12, 2006)

Okay, I shut of the low cut filters. Good news is I guess it shows a little higher output at lower frequency, but the overall response doesn't look as good to me. So here is the graph with the low filter off in comparison to on. The first is without filter, the second is with low cut filter. The third is a measure with the mike close to the subs, near field. I guess this is a more accurate reading if comparing to the Polk and Earthquake, since that is how I measured them.


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## brucek (Apr 11, 2006)

Yeah, that looks better. 

I would stop doing the near field and do your measuring at the listening position.

Let's discuss graph 1, which is your IB sub with the filters off - leave them that way.

If you increased the overall level of the measured signal, it would be quite good except you'd have a hump at about 5oHz. Fine, that can be eliminated with a BFD.

Go ahead and do a measurement of your IB at the listening position and set the Measurement level at about 90dB instead of 80dB. That should track your target except you'll have a peak at 50Hz......

BTW, is your BFD ready to rumble?

brucek


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## Matteo (Jul 12, 2006)

Here is the graph at a 90 dB range. To make sure I did this correct, I calibrated the REW for an 80dB reading, but my SPL was registering 90dB. So I fudged it 10dB. Is this how to properly test at a higher range? Also, I keep posting the original graph to give you something to compare to. Would you like me to stop doing that, or is it beneficial to have the side-by-side?
Roly
Also, not sure if my BFD is ready to rumble, but it is hooked up and looking pretty.


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## brucek (Apr 11, 2006)

> Is this how to properly test at a higher range?


No that won't do anything, sorry. The point I'm trying to make is that you have a large peak at 50Hz. It would be better for determining filters if your entire response was about 5-10dB higher. Set the entire procedure up using 85-90dB, but put the target at 80dB (you'll have to manually click the target thumbwheel after the setup to get to 80db). This will give more filtering to that large area around 50Hz. Try it and see what happens.

Just post the single graph....

Can you also attach your saved graph.mdat file next post so I have something to work with to provide pictures rather than words - it's so hard to describe some of this stuff in words. Save the measurement under the pull down FILE / Save Measured Data Set

brucek


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## Chrisbee (Apr 20, 2006)

roly

Can you double check you have all the microswitches on the back of your EP2500 amp pushed over to the *left*?

Only switches *3* & *8* should be pushed to the *right* if you are using the Behringer amp in stereo. 

Moving 3 & 8 to the right turns the bass filters off so you get the deep bass through to your IB. 

Double check you haven't moved any other switches if you do have to move 3 & 8 to the right.


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## brucek (Apr 11, 2006)

* CREATING AND ENTERING FILTERS*

roly,

This is probably a good time to discuss using REW to create recommended filters and then entering them into the BFD and then re-measuring to check the results. I'm assuming that the filters will be entered into the BFD manually from its front panel. The BFD manual can be used to describe how to enter filters.

So at this point, you have taken a raw measurement with no BFD filters and saved it as a *.mdat file (using the pull down FILE / Save Measured Data Set). You are able to load that mdat file at any time in the future to work on your filters, but you may as well do some filters now when everything is hooked up and enter them into the BFD so you can test how they work.

Something you have to realize about REW is that it won't automatically create any suggestions for filters for dips that require gain. It simply suggests filters that will reduce the peaks down to the target line. This is smart since it has no idea if a filter with gain will work in a system, due to the fact that some dips in response are a result of a room resonance that won't budge no matter how much gain you throw at it. 
In that case all you're accomplishing is to reduce your available headroom. So filters with gain are trial and error. If you have a dip, you can use REW manually to produce the best suggested filter with gain as if it would indeed respond. Then you enter that filter and do another response measurement and see the effect. Some dips simply respond exactly as REW predicts and some dips are very stubborn. Don't waste your time on them.

This part of the procedure requires some creativity on your part. REW will indeed automatically suggest some filters for you to enter (after pushing a few buttons) and shows on the graph the likely result after entering them. The predictions are remarkably accurate. If you just followed the advice of REW for filters you would remove all the worst peaks and your system would sound better. This just doesn't satisfy most people though. The fact is, after you have pushed the buttons to get the filters that REW recommends, you should use REW in the manual mode and play with the filters by adding your own and modifying the suggested ones until you get a smooth response predicted on the REW display. Then enter those filters into the BFD and see if the response is as REW predicts, and then tweak a bit to get it perfect.

Let me go through the procedure and show a few pictures.

Once you've taken the raw measurement and have saved that mdat file, it's time to let REW suggest filters.

I'll use my own system in the pictures. Here's my raw measurement and my target. My target is 80dB, but I have added a house curve to the target and have a crossover at 60Hz, so my display will look somewhat different than yours.









*1. FIND PEAKS *
Press this button and REW will find the peaks within the limits of the find peaks default entry of 20Hz to 200Hz. I usually set this first to 15Hz to 200Hz. Remember a BFD can only enter filters down to 20Hz, but I get better suggestions from REW with a lower limit of 15Hz.
REW will find the peaks and display them in a persistant chart in the left hand side of the graph. You can see by the little chart that the frequencies are at the peaks. I suggest *every time* this chart pops up to remove it with a couple Cntrl-Shift-P's.
Here's my own systems raw measurement and the associated FIND PEAKS chart. It shows, for example that there is a 10.2dB peak at 34.5Hz.









*2. ASSIGN FILTERS *
Now press this button and REW will assign appropriate filters to attempt to remove the peaks it found. The suggested filters are displayed in the bottom right hand corner of the REW page. The green entries are the actual BFD front panel entry for the frequencies. 
Below are the suggested filters:










*3. OPTIMISE PK GAIN AND Q *

Press this button to automatically adjust the gain and Q settings of the suggested filters to obtain the best match to the shape of the peaks and so create the flattest corrected response. The corrected predicted response is now displayed along with the graph of the filters. The display graph gets very busy now.
You can remove all the extra stuff on the graph now to get a better picture of what the predicted corrected response will be. Turn off Sub Measured, Filters and Filters+Target to reveal only the target and the SUB CORRECTED response. At this point, if you simply entered those suggested filters, your response would look fairly close to the predicted response that REW now shows.

Below is the predicted response if I used the filters suggested. See the filter numbers along the top of the graph - kinda handy.









*GET CREATIVE*

Here's where you play with the filters manually by adding your own and also modifying the suggested ones to arrive at the best and flatest response (without getting too crazy). I ended up with quite a few extra filters as you can see by the diagram below. When you modify and add filters be sure to press the *ADJUST PK GAINS* after you do so......Play around with the parameters of each filter and see what it effect is on the response - REW dynamically shows you the results.









Below is the actual response (and very close to the predicted) that I achieved by the new and improved filters shown above. The predicted and actual were very close.









Once you like the look of the predicted graph it's time to enter the filters into your BFD and then do another REW response check to see if the actual response is as good as the predicted response. Where it will possibly differ is in the areas where a filter has gain.

*Read the next line carefully because it's quite important!*

When you do the new response sweep after the filters are entered into the BFD, you must temporarily clear the filters out of REW so they don't affect the new measurement. Just uncheck the boxes as shown below or the filters shown in REW will be applied to the new sweep measurement.
If you don't like the new response you obtained with the filters that you've entered into the BFD, you can reload your raw mdat file and then uncheck the filters and play some more. It can be several iterations (or not) before you're satisfied with the response. (You can see why the midi cable would be handy at this point). I don't have one myself, but I get why it's nice to have...










brucek


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## Matteo (Jul 12, 2006)

Very Exciting stuff,
So you are telling me that by leaving the REW SPL at 80, but actually having an output of 90 on my RS SPL, this won't achieve the 10 dB increase I am looking for. My thinking was that since REW is thinking it is seeing 80 dB, but is really being fed 90 dB, that my response would be 10 dB higher. I will try to reset the whole procedure and see what happens. So let me ask yet another stupid question. If I am EQing my subs for lets say a 90 or 100 dB signal, because obviously 80 isn't doing the trick, when I get all finished and I go to set up my system, what will happen. Say I just use my autosetup on my processor, it would set all the speakers to the same level, lets say 80dB, correct. So then my subs would be down into the sissy range again. Does this mean all my setups are going to mean I add a little more output to my subs to get them looking/sounding correct? So if I want good, deep bass I will always be turning the bass up from reference level? Just not sure how that all works. 
Chrisbee,
All my filters are to the left, except for 3 and 8, and I think 2 and 9. 3 and 8 turn off the filters, I believe, and the other 2 turn the filters to a 30 Hz cutoff. I suppose it doesn't matter if those 2 switches are set to 30 or 50 since I have turned the filters off, correct? I can easily switch them back to the 50 Hz mode if it makes a difference, but I don't think it does. Thanks for the reply.
Brucek,
Another thing I didn't mention is that I might have some more work to do on my sub box(riser) before all is said and done. ThomasW at HTGuide, told me that when I finished the box and took some measurements he would help me to "tune" the subs by adding insulation, or batting, to the inside of the riser. Right now it is fairly hollow with only the top, bottom, and sides insulated. I think I remember hearing that by adding more "stuffing" it makes the box look bigger to the drivers. Not sure if that will make much of a difference in the way my subs respond, but I guess I should make sure that is taken care of and then do some more measurements. I am just waiting to hear back from Thomas. Thanks for the step by step on they BFD. When I get home from work tomorrow, I hope to do some more work on the subs. Thanks.
Roly


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## brucek (Apr 11, 2006)

> So you are telling me that by leaving the REW SPL at 80, but actually having an output of 90 on my RS SPL, this won't achieve the 10 dB increase I am looking for


That's correct, becuase the level in the room will be 90dB, but you've told REW that it's 80dB, so that's exactly where it will place it on the graph - 80dB......get it 



> If I am EQing my subs for lets say a 90 or 100 dB signal, because obviously 80 isn't doing the trick, when I get all finished and I go to set up my system, what will happen.


After you have added filters to get the best response possible, you can set your speaker level trims to whatever level suits you. Some people like their subs quite a bit louder than their mains and others prefer a flatter response. The level is up to you - but the BFD will be forcing the sub to provide a smooth overall response with no peaks, no matter what the level. (100db is a bit much, but 85dB to 90dB isn't for setting up REW).

What I was attempting to do for your first filter setting was to try and raise the entire wholesale level a bit of your sub and then knock down that 50Hz signal until it was closer to the level of the rest of the response. You could perhaps accomplish the same thing by leaving the 50Hz alone and raise all the rest using filters with gain, but I don't think that's a good idea.

By raising your overall level a bit to say 85dB to 90dB, while leaving the target at 80dB was to trick REW into supplying you with more reduction of the 50Hz (because more will be peaked above the target line). There's lots of ways of doing this. You could set the whole procedure up to 80dB as before and then just drop the target line to 75dB and then find filters - it will amount to the same result. Then of course you'll be tweaking manually anyway. Once you get playing with the filters you'll see what I'm getting at....

brucek


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## Matteo (Jul 12, 2006)

So my souncard has gain levels, as well as my Amp. Currently the gains are both set midway. Should I increase these as well as the volume on my reciever, or just use the receiver? Is there some rule of thumb for this?
Also, just tried to go back into my REW and run some tests and I am gettting this message: "Unable to access the replay device due to line with format PCM_signed 48000.0 Hz, 16 bit, stereo, 4 bytes/frame, little endian not supported."
I haven't changed any settings on my computer or REW since last time. Hopefully this is a common error with an easy fix. I will look at my computer and see if something has changed.
Roly
Edit: Nevermind. Not sure how I fixed it, but I did. I re-did my measurements just a few moments ago. Not sure what has changed. I reset my SPL and made sure everything was calibrated, and seemed to get a better response today. The second picture is with my amp's gain turned up 3/4 (all others have been at 1/2 gain). The third pic is 100% gain. So is this the easiest way to increase the output? I left the target at 80 on all. Let me know what you think. Thanks
Roly


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## brucek (Apr 11, 2006)

> So my souncard has gain levels, as well as my Amp. Currently the gains are both set midway. Should I increase these as well as the volume on my reciever, or just use the receiver? Is there some rule of thumb for this?


Just adjust the levels as before following the step by step approach and set the appropriate control for the step you're on at the time. Nothing has changed except I think it's wise to raise the setup from 80dB to a little higher (except keep the 80dB target level setting).



> Hopefully this is a common error with an easy fix


Your soundcard sample rate has been changed and isn't matching REW. Go to REW and pull down SOUNDCARD and check the sample rate - it should match your soundcards rate. You may have been playing with the sample rate of your soundcard by accident.

brucek


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## Matteo (Jul 12, 2006)

Okay, I think I am getting confused again. Raising the gain levels on my amp appeared to increase my measured response to be more similar to the target range. I thought this is what I wanted? I realize the graph looks similar, maybe identicle, only raised to a higher SPL level. Since I now have more of the response line closer to the target line, won't this be easier to EQ, or am I just not understanding something major. My first time. I will get better, promise. So if I don't use the gain on my amps and keep my first measure, I am uncertain how you suggest I raise the input on my subs. Can you give me a quick step by on how to do this? Also, what would I use the gain on my amps for or when would I use them? Is that for after the whole process is over and I just want some more volume? I have never been able to choose my Input Volume. I just use the default, which I believe is 75. Not sure if that matters. Thanks.
Roly


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## rlammi (Jul 2, 2006)

Hey Roly ,

From one nub to another I think brucek is saying just set the spl meter (plugged into your computer)and bump it up 5-10 db and then retake you readings and you wil get a truer reading of were to make your cuts and gain .
If I am reading what brucek said.You are doing reat by the way can't wait till I get time to run my first test now that I have my sound card calibrated :jump: 
good luck roly hope everything goes well and sounds even better.
Ron.


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## brucek (Apr 11, 2006)

> I thought this is what I wanted?


Yep, it is. I just didn't feel it was high enough to do what we wanted. But we're really going in circles here - so I think we'll accept that everything is good and carry on with creating filters (which of course is what all this is leading toward). 

So take your reading at 80dB as you did before and then carry on with the step by step filters stuff I wrote up (combined with following the HELP files).

Please, please save the raw measurement as a mdat file and attach it so I can have it... 

brucek

ps


> I am uncertain how you suggest I raise the input on my subs


Turn up your processor or subwoofer amplifier if it has a gain control



> Also, what would I use the gain on my amps for or when would I use them? Is that for after the whole process is over and I just want some more volume?


Yes. Normally before you begin the whole equalization process you set the processor trims to zero and then do a simple processor speaker level setup and balance the level of all speakers with the processor trims. You can adjust the gain of the subwoofer amp (if your sub amp has a gain control) along with the processor subwoofer output trim to set the desired level of the subwoofer for the speaker test.
After equalization you may need to tweak the sub gain up further with the trim or the amp volume.



> I have never been able to choose my Input Volume. I just use the default, which I believe is 75


75dB? The input volume is set up by pressing the input volume button as discussed. If REW can't obtain a high enough level then adjust the gain of your mic preamp gain higher. I don't see any reason to adjust the input volume - REW does it for you.

brucek


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## Matteo (Jul 12, 2006)

Here is my raw datea file. Sorry, was looking for some way to make it readable like the jpegs. The first is 80 target range, the second is 75.


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## Matteo (Jul 12, 2006)

Here is my data graph with REW doing all the EQing. Really took out that big peak at 50, but I am still really low on the lower end.


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## brucek (Apr 11, 2006)

Did you try a filter at 23Hz with some gain and a fairly wide bandwidth of about 15. Sometimes gain works magic and sometimes it does nothing. If it does nothing remove the filter.

You could also add a cut filter around 56Hz and 100Hz.

It doesn't look too bad though. 

brucek


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## Matteo (Jul 12, 2006)

Are there any no-no's when doing any of this? I can play around with it, I understand, and as long as I have saved my original data I am okay. But are there things to avoid. My first thought is to boost that low end, which I know may depend on my room and the trial and error thing. Are there certain sized bandwidths to avoid? How large can I make them? Also, I really don't care much about the frequencies above 120 or so, since my crossover is at 80. Why would I waste time on those high frequencies around 200? Just asking because I don't understand. Thanks for all the help. This is actually fun, so far. Can't wait until it is all finished.
Roly


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## Matteo (Jul 12, 2006)

So I have been playing around a bit with the manual EQ. Here is my response so far, just on the REW. Haven't tried anything on the BFD yet.


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## brucek (Apr 11, 2006)

You've done a good job. Hopefully the room will co-operate and the predicted will become the actual.



> My first thought is to boost that low end, which I know may depend on my room and the trial and error thing. Are there certain sized bandwidths to avoid?


Bandwidths can be any size, whatever works. Gain is the trouble maker. Sometimes you need to apply two filters side by side to get a result. If you have the filters available it's better to divide a large gain or cut in two and divide it between two filters. Two at +5db is better than one at +10db at the same or close frequency. The filters with gain shouldn't be too high, but there is nothing wrong with some gain if it works - you have a fair bit of headroom with your sub amp. 

Note you can save your filter settings in the BFD as a req file under FILE / Save Channel Filter Settings. Then you can recall the raw mdat file and recall the filters and play with them off line - at work perhaps... uhoh :devil: 



> Also, I really don't care much about the frequencies above 120 or so, since my crossover is at 80. Why would I waste time on those high frequencies around 200


Exactly. If you run out of filters you can steal filters from the higher frequencies since they have minimal effect. For example, your filters # 3, 4, 5 ,6. While they do a great job of making the response at that point close to the target, they are working in a frequency area where the signal is 20dB down and the mains will be overwhelming that frequency with their own signal. You may be able to use a single wider bandwidth filter there (that doesn't do quite as good a job) and steal three of the filters if you need them for lower frequencies.

Next. Since you are using an IB, you can't move it around to obtain a better response, but I wonder if you took a few other sweep measurements at a few different spots to see if you happen to be in a null where you're measuring. Some people have to average out their final EQ'd signal to satisfy a larger listening areas and some EQ for a single sweet spot.

Next step. Once you feel you're satisfied with your response, it's time to check the integration with the mains. This where you'll see the interaction at the crossover that sometimes creates a problem. You may have to adjust some of your filters to modify the results.

Turn on your two mains and do your sweep (with the BFD filters on of course) *exactly* the way you have been doing it. Now you'll get two pieces of information. 

One is that you'll find what the level balance between the mains and sub are. If you find the sub too low in relation to the mains, here is the time to turn up that sub amp (or the processor sub trim if you feel it needs a boost to get more level into the BFD evidenced by the BFD LED's). Some people like their sub 10dB higher than the mains and some like it flat - whatever you think. Adjust the level of the sub and redo the sweep until it matches where you want it.

The next information this test reveals is the crossover area interaction. You may find you have a bad dip now at the crossover. You might have to completely or at least modify filters in that area to smooth this overall response. A regular sub has a phase control to play with. This has quite a bit of an effect on the crossover area. An IB doesn't usually have that convenience, so you rely on filters to do the job.

Anyway, you have to get the sub completely EQ'd before you test with the mains, but now you know the next step anyway. Then you're done except for listening tests where you might adjust the overall sub gain up or down a little to suit.

brucek


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## brucek (Apr 11, 2006)

I've attached my attempt at your filters with an REW target of 75. I only needed 10 filters and only 2 have a small +5dB gain. The rest are cuts. I just wanted to show that you can do this offline. 

I suspect with the small amount of gain used in the filters that your actual will be fairly close to the graph I've shown.

Note, because you have an IB, I set the Graph Axis Limits down to 10Hz to observe extension. See how nice your response extends down very low. You can save and try my filter attempt or use your own.....

*RAW DATA FROM YOUR LAST MDAT FILE*









*RESULT WITH 10 FILTERS*









View attachment filtersR.req



brucek


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## Matteo (Jul 12, 2006)

Thanks Brucek,
Is there any advantage to using less/more filters, besides the time consumed creating them? Also, I noticed you only have one filter around 200Hz. I was curious why we bother with such high frequencies when we cut the sub so low? Does it just give a better slope overall? Also, I have heard a lot about house curves and that perhaps they sound better. Is this something I should play with or wait until I get the rest of my equipment setup? And last question, looking at my sub response, is there any reason why I couldn't use some M&K s-150's for my speakers. They are monitors and only have a frequency response of 82-20KHz +/- 2 dB. The sound great for theater, but I would hate to have a gap in my frequency. Here is a web site if you are interested or if it helps you to look at the stats. If you go to the very bottom of the page it lists the stats.
http://www.mksound.com/satellite_speakers.php
Thanks for taking the time on all this. I will play around with your graph as well. Oh, and just thinking, if someone where going to spec my frequency response,what would it be, based on our theoretical REW EQ? 
Roly


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## brucek (Apr 11, 2006)

> Is there any advantage to using less/more filters


Less would be considered better overall because it leaves unused filters that you may need later to adjust around your crossover, and also each filter introduces phase shift which may or may not be good. As I said before though, if you had a filter with a 10dB gain, I would divide it into a couple at 5dB. The filter file I provided allows two spare and no filters with gain above 5dB......



> Also, I noticed you only have one filter around 200Hz. I was curious why we bother with such high frequencies when we cut the sub so low?


Yeah, I answered that above in this post. Filters at 200Hz would really be considered useless and could be removed once you see the crossover with the mains is good and that when removing the ~200Hz filter had no effect on the sub + mains response.



> Also, I have heard a lot about house curves and that perhaps they sound better. Is this something I should play with or wait


Wait on that and see how it sounds.



> They are monitors and only have a frequency response of 82-20KHz +/- 2 dB.


Down 2dB at 82Hz..........I wouldn't recommend them for your system.



> Oh, and just thinking, if someone where going to spec my frequency response,what would it be, based on our theoretical REW EQ?


Well, hard to say. Looks like that IB is still going strong down to 10Hz. Who knows where it drops off. Safe to say it goes quite low and would be a step up from most retail box subs...

brucek


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## Matteo (Jul 12, 2006)

Okay, another dumb question. Here is a picture of the Axiom sub. A big sub, for sure. Here is what I can't understand. This sub appears to be kicking my subs butt, at least from 15-100 Hz. 90dB, straight across. Mabye mine goes better to 10, not sure. My first question is this. Is Axiom using the same type of test that I am? I understand this is a professionally built sub, but come on. I have some big honking drivers and a huge box. It makes me feel as if this whole DIY was kind of a waste. Don't get me wrong. I have learned a lot, which is worth a great deal, but I seem to have an end product that is barely superior, or even inferior, to a sub that might be around the same price, and with no stress involved with the creation of it. Let me restate this. I really enjoyed this process. I have enjoyed the learning aspect. I am eager to do more. I just seemed to be under the impression that this sub would be phenominal, not an average- nice sub. With the extra cost for materials, amps, BFD, etc, I must be nearing $1500. And, I can't use the speakers I like because the sub won't hit 80 Hz. Just kind of bewildered. Sorry to vent. Thanks for the help. I re-read some of your earlier statements. They are making more sense now. People can tell you what they know, but if you aren't at the right time in your education, it just kind of goes over your head. Thanks a ton Brucek
Roly
:dizzy:


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## brucek (Apr 11, 2006)

> This sub appears to be kicking my subs butt, at least from 15-100 Hz. 90dB, straight across


Thats a $1780USD Axiom EP600 in an *anechoic chamber* measurement and it's response is down -3dB at 17Hz and -25dB at 10Hz.

Your sub will eat this sub for lunch and still be hungry.

A room versus an anechoic chamber measurement are completely different.

You want 90db, turn your sub up. Go ahead, use REW as a simple sine wave generator by pressing the PLAY button and move the frequency down to between and 10Hz and 15Hz and crank your processor volume - now you'll have everyones attention in the house. 
You don't even have an SPL mic that will measure how low your sub goes.

The difference between 10Hz and 20Hz is where the real subs stand up. Seems to me your sub is extending down to 10Hz and still no sign of dropping off. Do you realize how hard that is to get with a commercial sub? Your sub kicks butt.



> And, I can't use the speakers I like because the sub won't hit 80 Hz


Huh, I'm really missing the point here. Your sub will easily hit 80Hz - but it's rolled off there by your processors crossover. The weakness is not in your sub, it's in the M&K S150 which is a small 23 pound monitor that is usually purchased as part of their M&K S150 THX Ultra System. It integrates well into their system where they'll have the sub crossed up to a higher level to allow the smaller satellites. 
You require a floor stander where the lower end extends to about 60Hz to integrate into your 80Hz crossover.

brucek


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## Matteo (Jul 12, 2006)

Man, you get up early BruceK. You on the east coast? Your reply time says 0427. 
As always, thanks for the reply. Okay, I am getting a better understanding. So if I brought home the Axiom and tested in my room with the same conditions, the graph would look completely different than the one they posted. Good. Thanks for making me feel better. I really was set on those speakers, so now I will be on another quest for some towers. I'll start a forum about it. 
I would like to push my subs a bit, just to see how they will sound and perform. Anything to be careful of? I don't want to max them, just push them. Your a great guy BruceK. Think my wife is getting jealous. :hail: 
Roly


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## Matteo (Jul 12, 2006)

I was just going to get working on my BFD setup, was reading the manual, and see it is a little different than the 1124. Probably not a big deal. I have the FBQ2496. I think I can figure out which buttons do the same as on the 1124. One question though is that I see my FBD has 20 channels per side. I know we were using 12 before, but I assume I can use the full 20 channels. Correct? Any major differences I have to be careful of with the 2496? Thanks.
Roly


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## brucek (Apr 11, 2006)

> Man, you get up early BruceK. You on the east coast? Your reply time says 0427.


Yep, I had to go out of town that day, and so was up quite early.



> I know we were using 12 before, but I assume I can use the full 20 channels. Correct? Any major differences I have to be careful of with the 2496? Thanks.


From my understanding, the 2496 indeed has 20 filters, but only one program - no other real differences. The 1124 that most use here has multiple programs. For example, I have a movie program and a two channel program that I use depending on what I'm listening to at the time. 

No big deal - set up your single program and you'll be fine. 

I really doubt that you'll need 20 filters though. If you use the filter.req file I created, you'll only need ten....

brucek


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## Matteo (Jul 12, 2006)

> I really doubt that you'll need 20 filters though. If you use the filter.req file I created, you'll only need ten....
> 
> brucek


 I tried to load that file and it wouldn't fully load everything. It said something to the effect that all of the filters wouldn't carry across. Maybe I did something wrong. Can you explain again, briefly, what is the difference between setting my target at 75, or 80, or any other number. The response looks the same. I see it creates a difference between target baseline and the peak of peaks. Are we just trying to manipulate the graph so less EQ has to be done, or is it something else?:reading: 
Roly


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## brucek (Apr 11, 2006)

> I tried to load that file and it wouldn't fully load everything. It said something to the effect that all of the filters wouldn't carry across


EDIT: I posted here earlier that it worked for me when I tried it, but then I remembered you had a FBQ2496 and not an 1124. 
This means you should select that model in REW. Under EQUALIZER pull down, you should select FBQ2496. 

I converted my filter file that I made to a FBQ2496 and attached it to this post. Just click and save it to a directory in your computer. 

I also attached the jpeg of the filters that you can just enter into your FBQ to test them if you want or you can load your raw mdat file and the filter file into REW and see the result.

To load a filter file:

Start REW and Select SUB tab.

Select *File / Load Channel Filter Settings* the file filtersFBQ.req from the directory where you saved it.

That's it - the filters will show in the filters area of REW...

Here's a pic of the ten filters in the filter file.









View attachment filtersFBQ.req






> Can you explain again, briefly, what is the difference between setting my target at 75, or 80, or any other number. The response looks the same.


The target is a value you can manually set at any time that has zero effect on the response and is only the level for the REW calculations to work with for creating the finding of peaks above that target value...that's it.


brucek


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## Matteo (Jul 12, 2006)

Okay, 
Played around with my BFD. A little different than the instructional page, but I used the owners manual and it seemed to work. Here is the response. Everything was calibrated. When I ran the BFD filters a message came up stating "the highest level in the measurement is 
-24.2" said it should be -10.0 and to turn up the processor volume. If I just turn up the volume on my processor, won't that mess up my measurement. If so, do I set up the entire thing again at a higher level, then retest with the filters. Also, at one point, it said clipping was detected on the input line. Not sure what is going on. First it is clipping, then not loud enough. Did I just overcorrect the levels? Anyway, how is the line looking? Also, the measurements I have been using have been for a target of 80. Can I use your line for 75 and just have a higher curve Brucek? 
Roly


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## brucek (Apr 11, 2006)

> When I ran the BFD filters a message came up stating "the highest level in the measurement is
> -24.2" said it should be -10.0 and to turn up the processor volume.


Sounds like what I've been saying all along. hehehehe. Even REW is telling you that now. 



> If I just turn up the volume on my processor, won't that mess up my measurement. If so, do I set up the entire thing again at a higher level, then retest with the filters


Yes, takes about two seconds.....



> Also, at one point, it said clipping was detected on the input line. Not sure what is going on. First it is clipping, then not loud enough. Did I just overcorrect the levels?


Likely....



> Anyway, how is the line looking?


I think it looks real good. :T 



> Can I use your line for 75 and just have a higher curve Brucek?


Of course. My target of 75 was only because that's what I used given the level you had done your raw measurement at the time. Once the filters are entered into the BFD, you can then remeasure at any **** level you want. You can also tweak any filters you want if you like it any different.

So, now it's time to do the exact same measurement, except turn on the mains (when they're ready) and set up the relative level between the mains and sub. Also at that time you may need to tweak a filter or two around the crossover area if there's any funny stuff. 

brucek


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## Matteo (Jul 12, 2006)

Er, um, I don't have any mains. No funds yet. My plan was to get my subs most of the way calibrated and running, then start adding to my HT, bit by bit. Tell you the truth, putting in that data to the BFD was really easy, even just using the manual to do it. Maybe I have not done it correctly, but I was figuring it would take me months to set up my amps, run measurements, work and re-work the BFD and add room treatments. I realize I have more work to do, but it really only took like 15 mins to read the manual and throw the numbers in. Let me know what I am doing wrong! :duh: Also, I would like to add any room acoustics if needed to help the bass. What would you recommend along those lines? How can I tell from my graph what types of room treatments would help and where to place them? Trial and error? I had planned to use the M&K s150's as mains, but I have been getting mixed signals on if they will work with my subs. They have frequency of 80Hz-up? Not sure if I can cross these subs at 80 and make it work. Have a thread going suggesting some other speakers that sound similar. One last thing. When my automatic meaure tone starts, I can hear it begin, then kind of dip or pause. Is that just the dip in my waveform that I am hearing, or is that the clipping issue, or both? 
Thanks Brucek.


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## brucek (Apr 11, 2006)

> Let me know what I am doing wrong!


Nothing. Entering the data manually is a breeze. That's the reason why I don't have a midi cable to do it automatically. It just seems too easy to enter by hand. Most of the work is in understanding REW... and once you get that down, setting up a sub is simple.



> I would like to add any room acoustics if needed to help the bass. What would you recommend along those lines?


I'm afraid I know very little about that stuff. Maybe post in another section for that help.



> They have frequency of 80Hz-up? Not sure if I can cross these subs at 80 and make it work.


The theory is that mains should have a specification of being only -3dB down at an octave below your crossover to blend properly. That means that an 80Hz crossover require a set of mains with a bottom end of 40Hz +-3dB. That's the reason most people can't get away with a 60Hz crossover. Not many mains are capable enough. 

That said, lots of people use mains that don't qualify, but still sound OK. I'm sceptical of a set that has an 82Hz bottom end though.... that's just not good enough. But you can test them if you're convince you want them. Doesn't hurt to try.



> When my automatic meaure tone starts, I can hear it begin, then kind of dip or pause. Is that just the dip in my waveform that I am hearing, or is that the clipping issue, or both?


Neither, that's just exactly how it sounds...funny eh



> My plan was to get my subs most of the way calibrated and running, then start adding to my HT, bit by bit.


Good idea, keeps you from rushing. But it must be painful waiting.... :sweat: 

brucek


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