First graph

**FguerraG** · **04-28-07, 06:06 PM**

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...

**brucek** · **04-28-07, 06:38 PM**

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

brucek

**FguerraG** · **04-28-07, 07:35 PM**

Is this better?

The axis have been corrected and the cutoff is at 80 which is how I got my crossover set up

**brucek** · **04-28-07, 08:05 PM**

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

brucek

**FguerraG** · **04-28-07, 08:58 PM**

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

**brucek** · **04-28-07, 09:09 PM**

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...

brucek

**FguerraG** · **04-28-07, 10:39 PM**

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

**Wayne A. Pflughaupt** · **04-28-07, 11:18 PM**

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

**brucek** · **04-28-07, 11:36 PM**

Quote:

I’d 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...

brucek

**MACCA350** · **04-29-07, 02:28 AM**

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

**FguerraG** · **04-29-07, 02:44 AM**

I guess the difference from the first graph to the last one is that I played with the sweep levels and also changed the spl calibration from 75 to 80db can't recall what I modified on the sweep level but will try again in the morning, anyway the dip on the 30 hz keeps coming up I guess I'm gonna have to move my sub from the corner to either the middle of the front wall or somewhere along the side wall

My sub is a B&W ASW 650

thaks for the help guys , I'm sure I'll get better results tomorrow~

**Otto** · **04-29-07, 08:06 AM**

Hi FguerraG,

I'd have to agree with MACCA -- we need to figure out how you are able to measure to 2 Hz with a solid output. Even the plots that are only shown to 15 Hz show solid output at that frequency. Something's going on to be able to measure that response. I wonder what would happen if you allowed REW to measure with no sound coming from your sub or mains (i.e., no sound period). That FR to 2 Hz is coming from somewhere, and I think we should ensure that you're measuring what you think you're measuring first.

That said, don't worry. It'll all come together soon enough.

How tight is your sub in the corner? It may be enough just to move it around in the corner first, before going out onto the front or side walls.

Good luck and let us know how it goes.

**FguerraG** · **04-29-07, 06:49 PM**

More Graph's

This one is with the sub Off

This one is the result of recalibrating the spl to 75db

here I moved the sub to the middle of the front wall

is this any better???

**brucek** · **04-29-07, 06:51 PM**

Quote:

is this any better???

The last one is pretty good. Did you use REW to show you what it would be like with EQ..

brucek

**FguerraG** · **04-29-07, 06:53 PM**

No but i saved the data , Finally I'm getting somewhere!!!

let me give it a try

**FguerraG** · **04-29-07, 07:58 PM**

This is the Eq Graph

Should I go ahead and dial this to the BFD?

**brucek** · **04-29-07, 09:57 PM**

Quote:

Should I go ahead and dial this to the BFD?

Yeah, looks pretty good. You can also tweak them manually in REW to get it better if you like (or not).

There is a 'sort' button on the filter panel that sorts the filters from low to high - (makes it a bit more convenient if you're entering them by hand).

Once those filters are entered you'll find you may have to turn up the subwoofer amplifier volume control a bit to compensate. Then you can remeasure and see how you did.

Then you turn on the mains and do the sme measurement and see how the mains and sub integrate together around the crossover frequency. Sometimes you need to adjust the phase or the time delay a bit on the sub to remove any new dip or peak caused by the mixing of the two...

brucek

**FguerraG** · **05-01-07, 02:34 PM**

This is the result of manually adding the filters to BFD

How could this be improved or should I leave it like that?

wha next?

**brucek** · **05-01-07, 03:21 PM**

Quote:

How could this be improved or should I leave it like that?

Looks fine. If it integrates with the mains, and the levels between the two sounds good, then you're done...........

brucek

**FguerraG** · **05-01-07, 04:40 PM**

I wish I knew what I was doing but I'm at a loss

Here is the graph with the mains on

thing is I don't really know what to look for

sound wise I had to crank my sub all the way up including my AV so I could get a little bass but not exactly what I was expecting , guess I'm a text book house curve case

still not sure what next

back to reading some more.

T

**brucek** · **05-01-07, 06:02 PM**

Quote:

Here is the graph with the mains on

I don't think so... The graph is no different than the sub only graph. Are you sure the mains were playing?

brucek

**FguerraG** · **05-01-07, 07:08 PM**

should I change the settings to use the speaker pink noise?

the mains where on not sure if that was the problem

**Otto** · **05-01-07, 09:07 PM**

Quote:

FguerraG wrote:

should I change the settings to use the speaker pink noise?

the mains where on not sure if that was the problem

Nah, you should still use the sweep to do the measurement. But I would have to agree with brueck -- the mains are probably not on. What you have indicated as sub-only and sub-with-mains plots look pretty much the same. Additionally, if you mains are on, they appear to be wayyyyy below the level of the sub. Perhaps that's the case, and the sub and main levels are just not properly calibrated.

If so, just use your SPL meter to set the mains to the same level as the sub. 75 dB is a good target. Your receiver may have a noise generator that will help you measure this on a per-speaker basis. Or, you can use REW's pink noise generator to measure each speaker. Of course, you would have the sub off when measuring the mains, and vice-versa.

Either way, something's wrong with that plot. Your graph that was posted here looks like it has the mains on.

Can you move your sub around? I don't like that big dip at ~30 Hz, and you might be able to improve it with some placement changes. Move it around and do a few more sweeps.

**Rodny Alvarez** · **05-01-07, 09:13 PM**

Can you do a sweep from 10Hz to 200Hz?

**FguerraG** · **05-01-07, 11:23 PM**

Thanks for the advise guys , the mains where off my mistake

also I have tried moving the sub around the corner, the side wall and even the back of the room only to get even deeper drops but around 20 Hz here is an example

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