graph of my sub

**baritone** · **09-14-07, 08:49 AM**

Below, I hope, is a graph of the my subs response to rew after applying some filters.If you could comment on the results please.I am using my av receiver and the FBQ2496 BFD:if I ever get around to finishing these tests, is it just a matter of disconnecting the computer and spl meter to get everything back to normal,has anything got to be done to the BFD settings.

regards:Alan

grahsofsubresponse.jpg

**brucek** · **09-14-07, 09:06 AM**

Looks quite good, although I might bring the 60Hz area down a bit more, but you can wait until you check the crossover. Now that the sub is equalized you have to turn on the mains with the sub and see how the two play together around the crossover area. Your goal is for the best transition. Measure the sub + mains in the exact same procedure you use to measure the sub by itself.

Sometimes the interaction of the two creates new dips or peaks that can be taken care of using the following methods in this order.
Phase control of the sub, time delay of the sub, additional or tweaking of existing filters.

brucek

**baritone** · **09-14-07, 09:34 AM**

Hello brucek

Thanks for the reply,how do you load the original filters back and then tweek them and then load them back again.

Thanks;Alan

**brucek** · **09-14-07, 11:52 AM**

Well, I assumed you saved the raw mdat file using FILE / SAVE MEASUREMENT and also saved your filters using FILE / SAVE FILTERS.

Then at any time you can recall the mdat file and filters and tweak by using FILE / LOAD MEASUREMENT and FILE / LOAD FILTERS.

Or you can take a new raw measurement and recall your filters and apply it to the new raw measurement.

brucek

**baritone** · **09-14-07, 12:11 PM**

Thanks for the reply and I did save those files,just a bit unsure about applying the filters for the sub to the sub+mains,I will now run the set up for the mains+sub.

Regards:Alan

**brucek** · **09-14-07, 12:22 PM**

Quote:

just a bit unsure about applying the filters for the sub to the sub+mains

You can simply take a measurement of the sub and mains (with the filters engaged in the BFD) and see how it looks. Then if it looks good or requires simple phase or distance adjustments, then you're done - no filter tweaking required. If it requires adding new filters or tweaking old ones in the BFD, you can play by hand from the front panel and take measurements every tweak to see how you are doing.

or another way (if you find you need to tweak filters or add new ones after the mains are added) is to take a measurement with the sub and mains with the BFD filters shut off. Then load your saved filters file into REW and apply it to the new mains + sub measurement. Then tweak and load those new filters...

brucek

**finalrinse** · **09-14-07, 04:40 PM**

When the mains are run with the sub, is it preferred to use just the two front, or all five or seven?
Thanks,
Tom

**brucek** · **09-14-07, 05:19 PM**

Quote:

When the mains are run with the sub, is it preferred to use just the two front, or all five or seven

Only the front 2 mains in stereo - never with a soundfield selected. When the sub is checked alone, that is also the mode it should be in only - stereo.

brucek

**finalrinse** · **09-14-07, 05:43 PM**

Quote:

brucek wrote:

Only the front 2 mains in stereo - never with a soundfield selected. When the sub is checked alone, that is also the mode it should be in only - stereo.

brucek

Ok - Thanks!

**baritone** · **09-15-07, 08:58 AM**

Hello everyone
below is the graph of my mains +sub,comments please.I am still confused as to the correct method of obtaining the filters back into REW to(1) check if they work and (2) to add to them or tweak them to reduce remaining peaks.The reason I say this is that I cannot seem to get rid of that peak at the end of the graph I seem to be adjusting filters,loading them back in but it won`t go away.
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**Otto** · **09-15-07, 09:52 AM**

Hi Alan,

Many times, we work on getting the sub's frequency response as nice as possible before re-integrating the mains. I'd suggest going that route first.

As to getting the filter selections into the 1124, are you using a MIDI connection, or are you planning on entering them by hand? Let us know your intentions in that regard and we'll get you going on adding filters.

**baritone** · **09-15-07, 10:27 AM**

Hello otto
I have done my sub`s response,see below, and brucek commented although it could perhaps be tweaked further, it wasn`t bad, so he said go on and put the mains in, so I did not use any filters until now with the mains.I am using a FBQ2496 with a midi connection.I got a bit lost with saving so many measurements and filters I was not sure what was in the FBQ2496 or what measurement I was on.The process I am not sure about is that you can transfer your filters to the FBQ for the measurement you have just done,does the REW software then have no filters if you want to check the result and you have to reload them back in again from the files and also adding to them to reduce other peaks.

grahsofsubresponse.jpgThanks;Alan

**baritone** · **09-15-07, 11:09 AM**

Hello otto

below is a graph of sub +mains before my attemps at using filters

sub+mains no filter.jpg

**brucek** · **09-15-07, 11:10 AM**

baritone,

I've merged your two posts to keep thread consistency. It avoids confusion to have the whole story in one thread..

brucek

**brucek** · **09-15-07, 11:20 AM**

Quote:

The reason I say this is that I cannot seem to get rid of that peak at the end of the graph I seem to be adjusting filters

That's exactly what should occur. Adjusting a filter in the subwoofer at frequencies above the crossover have less and less an effect as the frequency increases.

Look at this graph of an overlay of the voltage going to your mains and the voltage going to your sub as a result of bass management. The two combine together in the air to produce the final flat response represented by the red line (in a perfect world). See how adjusting a sub signal at 200Hz for example will have little to no effect on the final mains + sub result?

Your peak at the end of your graph is caused by the mains....

80crossover sub plus main.jpgbrucek

**baritone** · **09-15-07, 11:50 AM**

Thaks brucek/otto

I don`t know who is going to answer, I`m just vague on using the filters.When you transfer the filters to the BFd and then you want to take knew measurements,either to check on the results of adding those filters or to add additional filters to reduce further peaks, have you got to reload them(has REw still got the filters in from previous measurement or does it stat from none again) I do a measurement and the filters remove certain peaks,download those filters to the BFD, and then more tweaking has to be done,it`s how to get the filters back into the REW software and add additional filters to remove more peaks,sorry about this confusion

Regards:Alan

**baritone** · **09-15-07, 11:53 AM**

Hello brucek

sorry about above post must have been writing it as you where posting (it`s that long)

**brucek** · **09-15-07, 12:18 PM**

Quote:

I`m just vague on using the filters

I don't know what more I can say that I didn't already in this post.

Once the filters are in the BFD, they can be shut off and you can take a raw measure, or you can leave them on and you can take a filtered measure.

You download the filters at any time from REW or you can tweak them by hand from the front panel.

You can SAVE FILTERS at any time with REW and reload them at any time with REW with LOAD FILTERS.

To see the filters associated with a measure, press the EQ filters Icon.

brucek

**baritone** · **09-15-07, 12:21 PM**

Hello brucek

when I have finished taking measurements,the last set of filters downloaded wil be used by the BFD for use in my set up and its just a case of disconnecting the computer and leaving the BFD on all the time.
Thanks for all your help.
Regards:Alan

**brucek** · **09-15-07, 02:21 PM**

Quote:

when I have finished taking measurements,the last set of filters downloaded wil be used by the BFD for use in my set up and its just a case of disconnecting the computer and leaving the BFD on all the time.

Yep, but you don't have to leave the BFD on for it to remember its filters. They are stored until changed. But, for the reason of not hearing that turn on thump, most people leave their BFD's on all the time.

brucek

**Wayne A. Pflughaupt** · **09-15-07, 03:21 PM**

Alan, I think I get some of your confusion, as I’ve confronted the same situation myself.

Quote:

baritone wrote:

When you transfer the filters to the BFd and then you want to take knew measurements,either to check on the results of adding those filters

In other words, you want to know how to tweak the filters from the first sweep with the results you got with the second sweep. Right?

As you hopefully know, REW shows you on-screen the predicted results of the filters. Here’s what I do.

After manually tweaking the filters on-screen to get response to look the way I want (I never rely on the ones REW recommends), I load the filters into the BD, then take second sweep. Then I compare the second sweep with the first. As you may know (I assume that’s why you’re asking this), sometimes a filter doesn’t quite get the desired reaction – like it actually ended up cutting a bit less than it was supposed to, for instance. For the sake of this discussion, let’s say a filter at 65 Hz didn’t quite cut as much as REW predicted it would.

I open the filter panel for the second sweep, and manually enter the frequency value (65 Hz in this case) and bandwidth parameters of the filter used in the first sweep that didn’t get the desired result. Then I tweak the gain of that filter until the response looks like what I was shooting for in the first sweep. Typically that’s only a few dB. So let’s say that 65 Hz filter needs another 2 dB of cut.

Once the newly-tweaked response in the second sweep window looks on-screen like what I was shooting for in the first sweep, I go back to the first sweep window and open its filter panel, and apply an additional 2 dB of cut to the 65 Hz filter.

Then I take a third sweep to make sure 65 Hz now looks like what I’m shooting for. Make sense?

Quote:

or to add additional filters to reduce further peaks,

It shouldn’t be too often that you need an additional filter. Typically it’s just that an existing one needs to be tweaked. But if you do think you need an additional filter, you can just add it in the second sweep window.

Quote:

The reason I say this is that I cannot seem to get rid of that peak at the end of the graph I seem to be adjusting filters,loading them back in but it won`t go away.

As others have mentioned, you can’t EQ much of anything above your crossover point. The reason you have that peak is because your subwoofer level is wa-a-a-y low compared to your main speakers. It needs to be turned up to better match and blend with the mains.

Regarding your equalized graph from your opening post:

Personally I wouldn’t let that big hole at 45 Hz stand without trying to do something with it. That’s surely going to have a negative affect your sound quality. It looks too wide to be a true null, so I’ll bet it will equalize out.

To that end, I think you should start from scratch. Here’s what I’m seeing, first looking at your baseline graph.

I recommend moving the Target Level so that it’s slightly above the middle of your 45 Hz depression (you can find that control under the “Target Settings” icon, to the left of the screen). Using the new Target Level as a reference, you’ll easily be able to equalize the depression without applying excessive boost, and the peaks on either side of it, while not adversely affecting your sub-20 Hz response. (If the depression doesn’t respond to EQ, either not at all or only a little, then you won’t be able to do anything about it, save perhaps re-locating the sub. If that’s the case, remove all filters there.)

Be prepared, dealing with a depression that deep is going to place increased demands on your sub, any way you go about it. So I hope your sub has enough headroom. If not, you’ll have to live with the depression, or at least not having it only partially eliminated.

Regards,
Wayne A. Pflughaupt

**baritone** · **09-15-07, 04:34 PM**

Hello Wayne

thats very helpful,its as you say initially confusing, I can figure out what to do, but its knowing where the controls are to do it( ie. use the front panel) what and where is the front panel,(Shut off the filters) where do you do that...etc,because its the first stab at REW and not being very familiar with where everything is it becomes confusing.Now I`ve had a go at it I`ll start from scratch and hopefully make a better job of it.Thanks again.

regards:Alan

**brucek** · **09-15-07, 05:15 PM**

Quote:

what and where is the front panel

The front panel of the FBQ2496........................

Quote:

(Shut off the filters) where do you do that

Push the BYPASS button on the FBQ2496.

Have you read the manual of the FBQ2496

brucek

**Wayne A. Pflughaupt** · **09-15-07, 10:06 PM**

Quote:

baritone wrote:

Hello Wayne

thats very helpful,its as you say initially confusing, I can figure out what to do, but its knowing where the controls are to do it( ie. use the front panel) what and where is the front panel,(Shut off the filters) where do you do that...etc,because its the first stab at REW and not being very familiar with where everything is it becomes confusing.Now I`ve had a go at it I`ll start from scratch and hopefully make a better job of it.Thanks again.

regards:Alan

Reading this, I may have mistunderstood your dilemma. I thought you were having trouble with REW. Now I’m not sure if it’s REW or the 2496 you’re having trouble with...

Regards,
Wayne

**baritone** · **09-16-07, 02:33 AM**

Hello brucek/wayne

brucek: you are correct, it is in the FBQ249 section 4, I had however read the manual, but did not relate the "front panel" to this: apologies(thicko me)

wayne: essentially it is the practicalities of using REW, its just the hick-ups that easily throw me, I am sat here surrounded by sheets and sheets of the downloaded help files (+ by the way the BFD GUIDE) its the confidence to get on with things I lack.
I am going to run the set again from the start.Thanks to both of you for your help.

Regards: Alan

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