# New Sub



## t6902wf (Nov 14, 2008)

Here is a measurement of a new sub. I had a sealed sub in this room and it was very flat without EQ.

With this it appears to me that I have a peak and a null.

It was measured with a 140 meter. I know the reading is high but I could not seem to bring down the meter reading on the left when setting levels so I had to match the meter on the right.

I am not sure this reading is correct. The null has me baffled, there never was one before.

The sub is very close to where the old one was but it is about 18" closer to the wall. I am going to move it to the same position but it will take some doing.

What can cause erroneous data? Can a ground loop hum do this?
I have not listened to enough familiar data to make comments on the sound.


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## glaufman (Nov 25, 2007)

Whic sub is it? Ground loop hum in the US would be at 60Hz, not at the 52 you're seeing.
It's possible that being closer to the wall it's exciting room modes more than previously.


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## laser188139 (Sep 19, 2009)

So it is the null that concerns you, and not the 52Hz peak that Greg mentioned?

If you are closer to the wall, the null could be a simple reflection. You write that this sub is 18" closer to the wall than the previous one. If putting it in the same place is difficult, you could try moving it even closer to the wall. If it is a reflection, that should raise its frequency and could make it deeper. 

If moving the sub is difficult in both directions, you could try taking measurements from more positions to see what you learn. 

The good news is that, as people frequently set the crossover around 80Hz, the null won't hurt your overall response as much as it appears when looking at the sub alone. 

Bill


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## t6902wf (Nov 14, 2008)

The null concerns me more because I can not eq it out. I am going to move the sub and see if it changes the response. 
I'll post thebresult when I do.
_Posted via Mobile Device_


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## hybris (Jan 25, 2009)

As laser mentions, if you plan to use a crossover of 80hz or lower the null may not be a significant issue as your speakers will fill in the gap, so to speak.


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## glaufman (Nov 25, 2007)

Often a null can't be boosted out. It's caused by reflected waves out of phase cancelling each other (this can be modal or not). As you boost the direct wave, the reflected wave increases as well, netting no improvement. Sometimes all you end up doing is eating up your headroom.


oh yeah, and sorry if I was attacking the wrong problem.


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## t6902wf (Nov 14, 2008)

After viewing the subs FR as tested outside I think my concerns are not caused by the room.

Here is the outdoor measurement of the sub. It seems to have the same dip and peak.
Outdoor








My room









Am I correct that a dip of this nature can be taken up with EQ?
If so is it wise?


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## glaufman (Nov 25, 2007)

Seems like I've done it again. I was looking at 100-110Hz... just to be clear, where is the dip that concerns you?


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## laser188139 (Sep 19, 2009)

Okay, at least we are starting to see what concerns you. I too was confused, focusing on the sharp dip above 100 Hz, as the dip below 52Hz seemed too broad to be caused by something in the room. 

For whatever reason, your chart is showing that in an anechoic environment your sub has a dip below 50Hz, that peaks up around 52Hz, then drops back down. And it does make sense that the gradual slope below 30Hz in the anechoic environment becomes flat when room gain is present at the low end. 

Given it is a characteristic of the speaker, and not of the room, I would think you can safely address the region below 52Hz with equalization.

Bill


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## t6902wf (Nov 14, 2008)

laser188139 said:


> Okay, at least we are starting to see what concerns you. I too was confused, focusing on the sharp dip above 100 Hz, as the dip below 52Hz seemed too broad to be caused by something in the room.
> 
> For whatever reason, your chart is showing that in an anechoic environment your sub has a dip below 50Hz, that peaks up around 52Hz, then drops back down. And it does make sense that the gradual slope below 30Hz in the anechoic environment becomes flat when room gain is present at the low end.
> 
> ...


Yes now you are with me.


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## t6902wf (Nov 14, 2008)

Should this response be EQ'd or best to leave it alone.


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## Ricci (May 23, 2007)

Cut down the 54hz peak with some sharp eq. It is not only loud, but it also rings a lot. It is an internal resonance in the sub. It sounds much better when you cut it back quite a bit. 

GL getting things dialed in.


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## t6902wf (Nov 14, 2008)

Ricci said:


> Cut down the 54hz peak with some sharp eq. It is not only loud, but it also rings a lot. It is an internal resonance in the sub. It sounds much better when you cut it back quite a bit.
> 
> GL getting things dialed in.


How about bringing up the 30 to 50 range?


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## glaufman (Nov 25, 2007)

As Bill said, there's a good chance you can eq that up. Try it, see how it works.


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## Ricci (May 23, 2007)

t6902wf said:


> How about bringing up the 30 to 50 range?


I would not recommend that. If anything you need to cut the lowest bass below 35hz down about 10db. A shelving filter would be great for that. That is some absolutely crazy room gain. Are you sure that is accurate?You are showing about 15db of gain at 20hz and 20db or more by 10-15hz. (Easiest way to check is to put the mic right in the center of the mouth at about 3" distance and raise the xover as high as it will go. Take a measurement there and make sure that the input doesn't clip. If it looks comparable to DSL's graph you are fine.) 

The dip in between there and 50hz is also impacted by the room too as the cab's response is only about 3 or 4db. 

You should cut at 54hz too. It rings badly there.


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## t6902wf (Nov 14, 2008)

Ricci said:


> I would not recommend that. If anything you need to cut the lowest bass below 35hz down about 10db. A shelving filter would be great for that. That is some absolutely crazy room gain. Are you sure that is accurate?You are showing about 15db of gain at 20hz and 20db or more by 10-15hz. (Easiest way to check is to put the mic right in the center of the mouth at about 3" distance and raise the xover as high as it will go. Take a measurement there and make sure that the input doesn't clip. If it looks comparable to DSL's graph you are fine.)
> 
> The dip in between there and 50hz is also impacted by the room too as the cab's response is only about 3 or 4db.
> 
> You should cut at 54hz too. It rings badly there.


The next time I measure I will check the freq at the mouth.

I have a BFD on order, I will post back when I have questions.

I asked TD and he said I could go either way with a cut and/or a boost.

I am thinking I may do a bit of the shelving then a slight boost between 30 and 50, cut the top off that peak and see what it sounds like.


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## t6902wf (Nov 14, 2008)

Ricci said:


> I would not recommend that. If anything you need to cut the lowest bass below 35hz down about 10db. A shelving filter would be great for that. That is some absolutely crazy room gain. Are you sure that is accurate?You are showing about 15db of gain at 20hz and 20db or more by 10-15hz. (Easiest way to check is to put the mic right in the center of the mouth at about 3" distance and raise the xover as high as it will go. Take a measurement there and make sure that the input doesn't clip. If it looks comparable to DSL's graph you are fine.)
> 
> The dip in between there and 50hz is also impacted by the room too as the cab's response is only about 3 or 4db.
> 
> You should cut at 54hz too. It rings badly there.


I think the big room gain is because my main listening position and the measurement is around 3 feet from the back wall.

I need some help with setting up filters.
Can I send you the measurement file for suggestions. PM me an email address if you are interested.


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## Wayne A. Pflughaupt (Apr 13, 2006)

I notice you’ve removed the Target Curve from your graph. If you re-align it to ~92 dB, and perhaps add a house curve, the Target will start to drop above ~30 dB. This would mean a less drastic boost in the 40 Hz range would be needed, compared to equalizing for flat-line response.

Also, REW has a feature that will recommend filters for the BFD, based on your Target Curve. Give that a run and see if you like it; if not, we can recommend filter settings.

Regards,
Wayne


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## t6902wf (Nov 14, 2008)

Here is a rookie first pass at EQ. I was messing this a house curve and I don't think I get it. Any suggestions are appreciated.


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## glaufman (Nov 25, 2007)

Suggestion 1: Like Wayne said, put the target curve on the graph you post.:bigsmile:


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## t6902wf (Nov 14, 2008)

Second try with target line


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## glaufman (Nov 25, 2007)

Hmmm... why do you seem to not have a mic or soundcard calibration file loaded?


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## t6902wf (Nov 14, 2008)

This is a saved measurement. I used the soundcard and mic calibration files when it was created. I did it on my home pc and I am working on filters on another PC


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## JohnM (Apr 11, 2006)

t6902wf said:


> This is a saved measurement. I used the soundcard and mic calibration files when it was created. I did it on my home pc and I am working on filters on another PC


That can be tricky with REW V4, as actions that recalculate the frequency response (such as applying IR windows) would give a result that doesn't include the cal file corrections. The corrections may be small through the range of interest, but better to know. Safest is to have the cal files on any PC you use and make sure they are loaded. In REW V5 the cal data is saved inside the measurement so this problem can't occur.


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## t6902wf (Nov 14, 2008)

JohnM said:


> That can be tricky with REW V4, as actions that recalculate the frequency response (such as applying IR windows) would give a result that doesn't include the cal file corrections. The corrections may be small through the range of interest, but better to know. Safest is to have the cal files on any PC you use and make sure they are loaded. In REW V5 the cal data is saved inside the measurement so this problem can't occur.


Thanks for the tip I will re-gin the filters on a PC with the cal files.


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## t6902wf (Nov 14, 2008)

Here is the Response I am going with for now.









Here are the three main seats










I EQ'd it flat and it was not good. I attempted to make a house curve using the natural output of the sub/room.

I run the sub about 3 db hot. I ran the most demanding scenes and the sub was under control and the clip light stayed off.
I did not try and smooth out every little bum. This was done with 5 filters, 3 cuts and 2 bumps.

Any thoughts?


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## Wayne A. Pflughaupt (Apr 13, 2006)

Looks good. It's always nice when you can have such uniform response at all the main seats. :T

Regards,
Wayne


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## Ricci (May 23, 2007)

Time to add the mains into the mix and see if you can get them to fill in that 100-120hz area. :T


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## t6902wf (Nov 14, 2008)

Ricci said:


> Time to add the mains into the mix and see if you can get them to fill in that 100-120hz area. :T


I did measure it. I'll have to check on my home computer. The 100 up looked OK. I'll try and post it.

I an thinking speaker upgrade next year. My mains are 10+ year old Paradigm LCR 450's. They are a MTM sealed design. I have 3 identical speakers for my fronts. They can't keep up with the sub.


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## t6902wf (Nov 14, 2008)

Here is the sub with the mains. That peak at 90 is the room (I think).










With Audyssey it was ugly.


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## Ricci (May 23, 2007)

Looks like you could stand to turn the mains down a hair even. 

Audyssey butchered things? :nerd: I've got 2 units with it and have yet to use either one because I keep seeing posts like this, plus I just don't trust automated processes made for the "average user".


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## t6902wf (Nov 14, 2008)

Ricci said:


> Looks like you could stand to turn the mains down a hair even.
> 
> Audyssey butchered things? :nerd: I've got 2 units with it and have yet to use either one because I keep seeing posts like this, plus I just don't trust automated processes made for the "average user".


The rest of the plot trails off, the peak at 90 makes it look worse then it is.

I believe in the Audyssey theory, I am just having trouble with the reality.

Maybe if I EQ the sub flat, and then run Audyssey. Using dynamic EQ which is part of Audyssey is essentially turning on a house curve of sorts.

The problem is every Audyssey run is a 20+ minute ordeal and the house has to be very quiet. Then if you don't like it it was a waste. Thankfully changing the filters in a BFD is quick and painless.


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## laser188139 (Sep 19, 2009)

To date, I like the results of using Audyssey. With the mains, I get much better stereo imaging. The only significant problem I had was dealing with Audyssey's attempt to raise the level below the tuned frequency of my ported sub, especially with DynEQ enabled. 



t6902wf said:


> ... I am just having trouble with the reality.
> ...
> The problem is every Audyssey run is a 20+ minute ordeal and the house has to be very quiet. ...


My challenge has been to understand the reality. Investigating what Audyssey might be trying to do has taught me more than I imagined about how the response curve changes with mic position. If you think it takes a while to run Audyssey setup, try using REW to take measures of the combined curve and each speaker separately at eight measurement points around the Audyssey bubble. One can spend hours. 

Good luck,
Bill


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## t6902wf (Nov 14, 2008)

laser188139 said:


> To date, I like the results of using Audyssey. With the mains, I get much better stereo imaging. The only significant problem I had was dealing with Audyssey's attempt to raise the level below the tuned frequency of my ported sub, especially with DynEQ enabled.
> 
> 
> 
> ...


I would like Audyssey to work flawlessly. I think measuring the result of Audyssey with REW is flawed. I considered getting the SVS-EQ1 but its goal is flat. From my experience with EQ flat is not good to me.


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## glaufman (Nov 25, 2007)

t6902wf said:


> I think measuring the result of Audyssey with REW is flawed.


Do you mean you don't like what REW tells you Audyssey did to your response?
Or do you mean the "concept" of measuring Audyssey's result with REW is somehow an inaccurate respresentation of what has been achieved?


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## t6902wf (Nov 14, 2008)

glaufman said:


> Do you mean you don't like what REW tells you Audyssey did to your response?
> Or do you mean the "concept" of measuring Audyssey's result with REW is somehow an inaccurate respresentation of what has been achieved?


Yes and Yes.

The most recent Audyssey run caused a huge notch in the location I measured at. But I measured my three main seats with BFD and they look pretty good. One of the benefits of Audyssey is consistent response over a larger area. They also claim to tame the time domain.

I listened last night and the bass sounded best with my BFD EQ. I tried no EQ of any kind, Audyssey, Audyssey with Dynamic EQ and my EQ solution.

I can't comment on the upper end of the FR.

I am going to try hard to get Audyssey to play with the BFD.


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## glaufman (Nov 25, 2007)

Well, the only thing that could make it inaccurate is if you're placing the measurement mic for REW in a different place than you had the measurement mic for Audyessey. Depending on the frequency, a small distance can make a big difference.


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## t6902wf (Nov 14, 2008)

Here is the sub with Audyssey only. I don't want to have to boost the notch it created.










Here is the sub measured from the same position without any EQ









Here is the sub same position with BFD 5 filters 3 cuts 2 boosts









Finally here is the sub with mains and audyssey. 









My conclusion is that I do not understand what Audyssey is doing.
I might be better to not have run REW and been blissfully ignorant.


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## glaufman (Nov 25, 2007)

And your Audessey mic was in the EXACT same position as your REW mic?


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## t6902wf (Nov 14, 2008)

glaufman said:


> And your Audyssey mic was in the EXACT same position as your REW mic?


NO, very close. I hear where you are coming from but look at the three main seats there is hardly any variation. Nothing like what Audyssey created.


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## laser188139 (Sep 19, 2009)

t6902wf said:


> Here is the sub with Audyssey only. I don't want to have to boost the notch it created.
> ...
> Finally here is the sub with mains and audyssey. ...


That does not look like a null that Audyssey would create, but I've certainly see Audyssey increase a null when it attacked the peaks on either side of it. If you are interested, you can see what corrections Audyssey is applying by measuring the sub output from the AVR with Audyssey On and Off and comparing. My impression so far is that it is relatively restrained in its approach; it does not apply changes that would flatten the curve at the first measurement point but would worse the response that most of the others. 

As Greg was suggesting, that looks more like a room modal response. If so, it may show large variations with mic position, in either the x or y axis, or even height. It was very informative when I used the suggested formulas to compute where all the tangential and oblique resonances might be in my room. One of my experiments today will be to vary the height where I measure to convince myself that some of what I see in the 100Hz-250Hz range is related to my mic and ear position being so close to 1/3 the height to the ceiling. 



t6902wf said:


> NO, very close. I hear where you are coming from but look at the three main seats there is hardly any variation. Nothing like what Audyssey created.


I have some of those, where everything looks similar in the row where I sit, but the measures are very different two feet forward or back. 



t6902wf said:


> ...
> My conclusion is that I do not understand what Audyssey is doing.
> I might be better to not have run REW and been blissfully ignorant.


I know that feeling.

Good luck,
Bill


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## t6902wf (Nov 14, 2008)

laser188139 said:


> That does not look like a null that Audyssey would create, but I've certainly see Audyssey increase a null when it attacked the peaks on either side of it.
> Bill


All of those measurements are from exactly the same mike position and the same session of measurements. Take a measurment, turn on Audyssey, take a measurment....

That is certainly what Audyssey did to that particular mic position.

I thought about the SVS EQ1 but did not like the flat FR it attempts to create.

Being a bass head is not always easy.


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## glaufman (Nov 25, 2007)

But were they also exactly one of the positions that you measured with Audessey?


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