# Dual PB13 graphs



## corock (Sep 7, 2009)

I finally got around to filtering my SVS PB13-Ultras. I have them tuned to 15hz and applying filters with a BFD 1124p. Here's the graph of the pair of subs with Audyssey on but no BFD filters.







I created filters for a flat response and then 9 hard knee house curves in 1db steps from 2db up to 10 db. That way I have the flexibility of playing with all the curves while using the 10 presets in the BFD.
I accidentally erased my flat measurement so here are the 2db and 6 db house curves as examples of the results.














Ever wonder what Audyssey Dynamic EQ does to the curve? Here's a measurement of it while the BFD is bypassed. I have my target 10db house curve loaded as a comparison.


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

> ... 9 hard knee house curves in 1db steps from 2db up to 10 db.


Not sure what you mean by that... :huh:

Regards,
Wayne


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## corock (Sep 7, 2009)

I created 9 seperate house curves. the first with a 2db increase, the second with a 3 db increase, and so on up to a 10db increase. And then saved each curve as seperate presets in the BFD.


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## corock (Sep 7, 2009)

Wayne,
I was just looking at the first graph again and noticed Audyssey is creating a hinge at 40hz. Would there be an advantage to hinging my house curves at 40hz and using less filtering, or should I leave it hinged at 30hz like I have it?


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

As I understand, Audyssey's dynamic EQ function alters the curve with different volume settings. You'll probably want to keep the curve hinged in the 25-30 Hz range, but it's always best to experiment. You might like the Audyssey settings at low volumes.

By the way, it does look like you're over-equalizing. It's not necessary to "iron out" every little ripple in response. If you have filters with gains of only 1-2 dB and/or ultra-narrow bandwidth, like 4/60 or less (assuming you're using the BFD), they probably are not necessary.

Regards,
Wayne

Regards,
Wayne


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## corock (Sep 7, 2009)

Thanks Wayne,
Only the last graph has Dynamic EQ on. The first graph is purely Audyssey MultiEQ XT without DEQ engaged. In both scenarios Audyssey appears to be creating that 40hz hinge, which is fine, its easy enough to alter to 30hz. I see now its because thats where a reference line flattens out. Sometimes the obvious escapes those looking for complicated answers. You're right about my attempts to "iron out" the response. I have up to 7 filters on some of the curves, ones like 58hz and 66hz are only 4/60 wide. Are they doing any harm, or should I go back and remove them? Which frequencies would you go after, 80hz and 38hz? Or would you also do 31hz and 24hz. I'm refering to the first graph which is not using DEQ and has a flat target line.


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## tonyvdb (Sep 5, 2007)

Excuse my dumbness but what do you guys mean by "Hinge" looking at the graphs it seems odd that you loose so much SPL above 40Hz, What do you have the crossover set at? Dual 13 ultras should do much better than that.


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## corock (Sep 7, 2009)

I have my crossover at 80hz. Audyssey wanted to crossover the mains at 60hz and the surrounds at 40hz. But my speakers, both mains and surrounds are Paradigm Millenia 200's, which have very small drivers. therefore, I changed the crossover to 80hz. I'm sure Wayne can explain a hinge 1-million times better than I. But from my understanding, it is the frequency where you stop the climb of a house curve and everything below that is flat.


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

> In both scenarios Audyssey appears to be creating that 40hz hinge,


 Hard to say whether or not Audyssey’s doing it, or that’s just the way your response looks right about there. It’d take a baseline “pre-Audyssey” graph to tell.



> I have up to 7 filters on some of the curves, ones like 58hz and 66hz are only 4/60 wide. Are they doing any harm, or should I go back and remove them?


 Hard to tell whether or not they’re doing any harm, but they probably aren’t doing any good either. It’s generally best to use EQ only to the extent that it makes an audible improvement.



> Which frequencies would you go after, 80hz and 38hz? Or would you also do 31hz and 24hz. I'm refering to the first graph which is not using DEQ and has a flat target line.


It’s actually a pretty decent graph. The only thing really wrong is that everything below ~45 Hz is at a good bit higher level than what’s below 45 Hz (note that everything below 45 Hz is above the Target, while everything above 45 Hz is below the Target).

But even that might not be too bad, depending on if you’re using a hard-knee curve or not – you mentioned it, but only one of your graphs had it.

With the top graph, which appears to have no house curve, all it needs is a single broad filter, either to push up everything above 45 Hz, or pull down everything below 45 Hz (your choice).

Regards,
Wayne A. Pflughaupt


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## tonyvdb (Sep 5, 2007)

I have one pb13 and its graph is much more level until the 80Hz crossover, It just seems odd that yours slope downhill at 40Hz and is almost 1/2 gone by the time you get to 80Hz Something is not right in my limited knowledge. Have you played with the phase control on one of them?


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

corock said:


> But from my understanding, it is the frequency where you stop the climb of a house curve and everything below that is flat.


That sums it up pretty well. 

Tony, as far as so much SPL being lost above 40 Hz, keep in mind that the graph is not a baseline reading; it's after-Audyssey EQ.

Regards,
Wayne


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## tonyvdb (Sep 5, 2007)

Wayne A. Pflughaupt said:


> Tony, as far as so much SPL being lost above 40 Hz, keep in mind that the graph is not a baseline reading; it's after-Audyssey EQ.
> 
> Regards,
> Wayne


Hmmm, still seems odd as even after Audyssey it my levels still remained much more flat but you know this better than I do so It must be ok. I personally would want more SPL between 40 and 60Hz than what he is getting.


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## corock (Sep 7, 2009)

Its that sharp decline at 40hz that I was refering to as the "Audyssey hinge" as it seems to create a steep slope up to 40 hz and then flatten it after that. In my treatment of the response, Ive brought the over/under 40hz back in line with each other as indicated in graphs 2 and 3. I didn't measure the response without Audyssey on. I'll do that tonight and post it for a comparison to the Audyssey treatment.


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## corock (Sep 7, 2009)

Wayne,

I would have never tried to adjust that response with a single filter. Obviously my notions of equalizing are skewed. I lean towards a bass heavy sound, so I'll adjust my base line up and increase everything below 45hz. I thought of 10/60 as a wide bandwidth (that belief was formed because BFD's auto filters never seemed to go that high). I'll probably need to go a lot wider to raise that whole area. You'll have to influence my perception, how wide will I have to go in your estimation and where should I center it (I understand I'll have to experiment to see what works best).


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## tonyvdb (Sep 5, 2007)

Just for comparison sake this is my graph 
The green line is my A/D/S ms3u sub and the yellow is the PB13U
Both readings were taken after Audyssey was done


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## corock (Sep 7, 2009)

Tony, 
My subs are both corner loaded in a living room that's about 4500 cubic feet which is wide open to about another 5000 cubic feet of living area. Is it possible the corner loading is giving support to the lower frequencies while the rest is being lost to the large area volume? By the way, how do you overlay a FR graph? I spent about 10 minutes trying to figure it out yesterday and finally gave up.


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## tonyvdb (Sep 5, 2007)

My room is 4950 cubic feet, both subs are co-located in the same corner. 
Corner loading will in most cases boost the frequencies but not just the low octaves even the 40-60Hz range should be up more. I dont know what to think. Do you have bass traps set up in the corner?


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## tonyvdb (Sep 5, 2007)

I should also note that playing with the phase on the subs moved the dip that you see at 70Hz to above the 90Hz range where my mains carry the range very well ( have not posted the new graph). It was actually fun playing with REW as moving the phase I could watch the dip move up or down depending on where I had the knob turned.


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

corock said:


> By the way, how do you overlay a FR graph? I spent about 10 minutes trying to figure it out yesterday and finally gave up.


Look for the “Measured” icon. It’ll allow you to chose which measurements to overlay.



corock said:


> I lean towards a bass heavy sound, so I'll adjust my base line up and increase everything below 45hz.


 It’s all the same. After bringing down the <45 Hz area you could just turn up the sub’s volume to get the “bass heavy sound” back.

It’s more practical to decide which route will get the best results, as far as smoother response goes. In this case I think boosting the >40Hz area will work better.



> I thought of 10/60 as a wide bandwidth (that belief was formed because BFD's auto filters never seemed to go that high).


 That’s because of the way REW is programmed. It’s programmed for reducing ringing caused by room modes, not response-smoothing. The former typically requires tighter filters.


> I'll probably need to go a lot wider to raise that whole area. You'll have to influence my perception, how wide will I have to go in your estimation and where should I center it (I understand I'll have to experiment to see what works best).


Impossible to say. It’s best to just play with it in REW. Start with a 1/3-octave filter (that’s about 10/60 in BFD-speak) boosted 4-5 dB. Play with the bandwidth, frequency center and gain until you get things looking like you want. It’s possible it’ll require two filters spaced at something like 60 and 80 Hz, if you’re going for more of a straight-line hard knee house curve.

Regards,
Wayne


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## corock (Sep 7, 2009)

tonyvdb said:


> I should also note that playing with the phase on the subs moved the dip that you see at 70Hz to above the 90Hz range where my mains carry the range very well ( have not posted the new graph). It was actually fun playing with REW as moving the phase I could watch the dip move up or down depending on where I had the knob turned.


I didn't take any measurements with REW when I adjusted my phase. I just used an RS SPL meter to find the best boost. I noticed a slight turn in the phase knob gave me a 2 db boost but turning it any further would bring the dbs down.


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## Moonfly (Aug 1, 2008)

Wayne A. Pflughaupt said:


> As I understand, Audyssey's dynamic EQ function alters the curve with different volume settings. You'll probably want to keep the curve hinged in the 25-30 Hz range, but it's always best to experiment. You might like the Audyssey settings at low volumes.
> 
> 
> Regards,
> Wayne


Just an FYI. 

Dynamic EQ is designed to work similar to loudness correction curves. It basically accounts for variations in perceived difference between frequencies at different volumes, and its aimed at low volume late night listening specifically. If you play at ref level (zero amp volume on relative display) then DEQ does nothing, as you lower the volume its effect comes in gradually and alters depending on volume, increasing its effect as the volume drops. Its like loudness correction, but its not just a simple correction, as the name says, its dynamic and the correction curves differs with volume. It also takes into account information gathered when you implement your amps MulitEQ XT and works along side this, so it can also account for room acoustics as well as frequency perception.

More info here :T


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## corock (Sep 7, 2009)

Hi Moonfly,

I could rename Dynamic EQ to "Wife EQ", because if she's with me the volume is down and the DEQ comes on, if she's not around the volume goes up and the DEQ goes off.:devil:


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## Moonfly (Aug 1, 2008)

corock said:


> Hi Moonfly,
> 
> I could rename Dynamic EQ to "Wife EQ", because if she's with me the volume is down and the DEQ comes on, if she's not around the volume goes up and the DEQ goes off.:devil:


I feel your pain :crying:


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## corock (Sep 7, 2009)

Okay I had a chance to take some new measurements for comparisons. In the first graph the blue response is a baseline, no Audyssey or BFD treatment. The purple is with Audyssey MultiEQ XT, no DEQ or BFD.









This second graph causes me some concern. The purple line is the subs alone with Audyssey and BFD treatment, no DEQ. The blue line has the main speakers introduced into the measurement.









I seem to be missing a lot of SPL between 60hz and 150hz. Like I stated earlier my crossover is set at 80hz. It looks like there's something wrong to me.:rubeyes:


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## laser188139 (Sep 19, 2009)

corock said:


> Okay I had a chance to take some new measurements for comparisons. In the first graph the blue response is a baseline, no Audyssey or BFD treatment. The purple is with Audyssey MultiEQ XT, no DEQ or BFD.
> 
> This second graph causes me some concern. The purple line is the subs alone with Audyssey and BFD treatment, no DEQ. The blue line has the main speakers introduced into the measurement.
> 
> I seem to be missing a lot of SPL between 60hz and 150hz. Like I stated earlier my crossover is set at 80hz. It looks like there's something wrong to me.:rubeyes:


In the second graph, where adding the main seems to lower the freq resp on both sides of the crossover, the obvious hypothesis is that at the measurement point the mains are inverse in phase to the subs, and one is subtracting from the other. So I would go back to adjusting the phase controls and taking REW measures, not just SPL measures, to see the effects. Of course, with two subs and two phase controls the experiment becomes more complex. Changing the phase of the subs relative to each other probably impacts the Audyssey measurements, so you might consider running these experiments with Audyssey off, or re-running the Audyssey setup to confirm the results after determining the apparent best choice. 

Bill


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## tonyvdb (Sep 5, 2007)

Yup, Thats a clear phase problem and I still think your subs are also canceling them selves out between the 40 and 80Hz range as well. This is going to take time but the first thing you should do is turn one sub off and get it working with the mains and then turn it back on and adjust the phaze on that one untill you get the proper results.


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## corock (Sep 7, 2009)

Looks like I've got some work ahead of me. I won't be able to get at it on Sunday...have to watch the Roughriders shock Montreal in the Grey Cup. Go Riders!


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## Moonfly (Aug 1, 2008)

If your concerned about phase interaction, I would start at the beginning. Measure each sub individually so you can see its natural in room response, no DEQ or Audyssey. Then do a combined measurement so you can see what interaction is happening between them. This will highlight any phase issue between the subs. If you have non then great, you just need to do a speaker only measurement, a speaker plus subs one, and overlay the 3 graphs (subs only, speakers only, then speakers+subs) to again highlight what possible phase interaction is going on. This process of illumination will show you if you have any phase issue to be concerned about in your room, and point out exactly where you should target your efforts in reducing them.

The hardest bit will be if your subs are out of phase with each other and the speakers at the same time, hopefully that wont happen but if it does the best solution could well be moving things about to take a look on how placement is affecting things etc. I would tackle that only if it comes to it though. For us to be able to help with diagnosis though, in each case we need to be able to see a 3 graph overlay as this shows exactly what interaction is going on. To start off, we need a sub 1 alone, a sub 2 alone, then a combined sub response, all overlayed on the same graph. Having variable phase could pay dividends here.


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## corock (Sep 7, 2009)

Okay here are my measurements to see if I have any phase issues. These are baseline measurements, no treatment from Audyssey or BFD. pink is left sub, blue is right sub, green is both.









Here is the combination of the subs and mains. Green is subs, blue is mains, pink is both.









I notice I'm not losing spl when the mains and subs are running together now. I haven't adjusted the phase. The only change I made is I removed the ART Cleanbox II, and the previous measurements where I was losing spl were with Audyssey and BFD filters in place.


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## Moonfly (Aug 1, 2008)

Sweet, spot on that, cheers.

Right looking at that lot there are exactly zero glaring phase issues anywhere, which is a result :T. Anywhere you have dips in one particular subs response (probably due to room modes), the other is filling in nicely just as it should.

At this point, you could decide to experiment with phase just to chase that extra 1%, but that'll drive you mad for hours for what will probably be improvements you dont really notice. Same goes for the speakers, everything is integrating quite well so personally I would leave it there myself. There is a slight dip right on 80hz, but I would probably live with that, partly because Audy will probably help with a dip that small, but partly because you have 2 subs making the phase adjustment that much more difficult to get bang on.

Now I would play with the subs tune modes, and find the one that gives the best (flattest) in room response. Bear in mind, any room boosting thats too much can be reigned in room comp, so if your flattest response (above about 20hz) has a wild low end, pick that mode and apply room comp to get the best overall response. Do the subs one by one at first, you may find they work best in different tune modes, but thats for you to figure out. We can help if you get stuck though. At the end of this you should end up with your subs in the best tune modes for your room. Then run a sweep of them together to check your work, if you find that the subs in different modes work against each other then you might have to put them both in the same tune mode. If this is the case then try the subs in each others mode and find which of the 2 settings works best overall and then stick with that.

The next step for me would be to manually balance the subs. Do it with just the sub tone from your AVR. At this point just aim for a balanced setting on the subs own gain dials, and if you like to run your sub channel a little warm, then set them both at 75db each (measured alone) and you will end up with around 78 combined. Once thats done, measure your subs again with REW and from this point forward, only doing the 2 subs together. Your first measurement will show you the natural response and give you a point of reference from which to work. Apply your filters to even the subs response out till you feel you have it pretty good, and with having two subs your could apply a small bottom end boost if you feel you need to although I would be surprised if that was necessary.

That should leave you with both subs balanced, in their best tune modes, with phase correct and their response manually flattened out. Now its time for Audyssey to do its bit, finalise the subs response, and bring the speakers nicely in. I would check the post Audyssey sweep with REW for confirmation/peace of mind and you should be set up then. If you find problems with Audyssey, as some people occasionally do, dont forget you only need to re-run Audy again, everything else will be at its best from the manual setup you did and shouldnt need touching again. If you would like help with Audyssey, I can post the method I use which I find reliable.

Of course, its upto you if you want to go ahead doing any of that. If your happy now then I probably wouldnt, but I figured I'd post my thoughts anyway.


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## laser188139 (Sep 19, 2009)

corock said:


> ...
> 
> I notice I'm not losing spl when the mains and subs are running together now. I haven't adjusted the phase. The only change I made is I removed the ART Cleanbox II, and the previous measurements where I was losing spl were with Audyssey and BFD filters in place.


The obvious inference is that at least one of these three devices was affecting the phase. After the balancing recommended by Moonfly, you may want to add the other devices one at a time and re-measure. Or add them all, verify the issue still exists, and then start removing them one by one to see what happens.


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## Moonfly (Aug 1, 2008)

You'll have to excuse my ignorance, as I'm unfamiliar with the Cleanbox. There is every chance that if a device is some kind of signal processing then it will cause an effect similar to a phase shift. Most digital auto EQ devices like the Antimode or EQ1 add a little extra distance to to the actual measurement to account for the signal processing time. Its possible that a delay in the signal is being caused by one of the mentioned devices resulting in an apparent phase shift and cancellation. Analogue devices introduce no delay, but can introduce a phase shift directly. As you can see, phase shifting, speaker distances and signal delays are very closely related.

Such devices would have to be directly affecting the subwoofer signal for that to be the case tough.


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## corock (Sep 7, 2009)

Thanks for all the advice guys,

Moonfly, I have the subs balanced but I tested the different tunings only as a pair. I haven't tried them seperately to see if one would be better at a different tune than the other. I'll will give that a go soon. I interperet your directions to mean that you suggest I flatten the response with the BFD before running audyssey. I've seen others recommend the other way around. Should I also assume that the spike at 38hz should be tackled with the SVS onboard PEQ.

Bill, I think I'm going to leave the Cleanbox out of the equation. I put it there because I had a slight 60hz hum, but in my experimenting last night I notice that without the Cleanbox the subs were at 75db at -11 on my master volume, with the Cleanbox I had to turn the master volume up to -8. That doesn't appear to me to be very transparent. It would seem to me its removing a lot more than just the hum.


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## corock (Sep 7, 2009)

Moonfly said:


> . There is every chance that if a device is some kind of signal processing then it will cause an effect similar to a phase shift. Most digital auto EQ devices like the Antimode or EQ1 add a little extra distance to to the actual measurement to account for the signal processing time. .


Is it possible my BFD is causing a phase shift?


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## Moonfly (Aug 1, 2008)

corock said:


> Is it possible my BFD is causing a phase shift?


Well its certainly not impossible, although it should be to small to notice really. In any case, running Audyssey after you use the BFD will help.

I would definitely do the BFD first for two reasons. First is that the more help you can give Audyssey the better job it does. Its a good free feature but has its limitations, the less work it has to do the more focus it can apply its filters etc to the problem at hand. Second is that you want Audyssey to be the last thing you use, otherwise your messing with the work it has done, and your changing the response it has measured and is working to. 

If you mainly use the BFD to apply cuts, then any ringing in your room will reduce as the volume of those frequencies reduces, again this is helping Audyssey out. As for that spike, it will probably be easier to target it with the BFD, unless you know specifically its being caused by one sub only (which it isnt), and you implement thats subs PEQ to help reduce the spike. If its being caused by both subs and is therefore a global room mode (which it is), then again using the BFD is the easiest option.

Regarding the tune modes on the subs, chances are if they are stacked then then same mode will be best for both. It looks from the graph though that they are spread out. By finding the flattest mode for each sub, you might be able to play the tune modes against each other, or rather get different tune modes working together against your room modes. This should achieve the flattest response, and its the main reason for implementing 2 subs in a setup. If your enjoying the playing around with EQ, its well worth looking at IMO.


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## brucek (Apr 11, 2006)

> Is it possible my BFD is causing a phase shift?


It's guaranteed to cause phase shift. It's inherent with IIR filters.

brucek


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## Moonfly (Aug 1, 2008)

brucek said:


> It's guaranteed to cause phase shift. It's inherent with IIR filters.
> 
> brucek


Its worth noting though that some people exhibit no issue with using the BFD when looking at the graphs.


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## corock (Sep 7, 2009)

In my first graphs, where there appeared to be a phase problem, I was applying BFD filters after Audyssey treatment. If I apply the BFD filters first is it possible Audyssey will compensate for any phase shift the BFD causes?


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## brucek (Apr 11, 2006)

> Its worth noting though that some people exhibit no issue with using the BFD when looking at the graphs.


Of course, since the signals from the mains and sub may arrive at the listening position in a non-canceling fashion. This doesn't preclude the fact that every filter causes phase shift. Its effect at the listening position may be helpful or it may be harmful.



> If I apply the BFD filters first is it possible Audyssey will compensate for any phase shift the BFD causes?


Certainly, it will do its best to smooth the response at the crossover to account for any cancellation caused by phase shift. This is one of the reasons you find Audyssey sub distance values being so far from actual - it uses time (distance) to shift the phase at the point of measurement. So, it's always best to set your BFD filters for the sub before running Audyssey. In addition, Audyssey does a far better job when it doesn't have large compensations to make.

brucek


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## corock (Sep 7, 2009)

Thanks for all the help.

The amount of time you experienced guys put in to help us newbies is amazing. It's very much appreciated. Put me down as a platinum supporter, its a deal for all the tools and support I've received from this forum. I'll be sure to revive this thread with measurements of the results I get from your advice.:bigsmile:


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## Moonfly (Aug 1, 2008)

brucek said:


> Of course, since the signals from the mains and sub may arrive at the listening position in a non-canceling fashion. This doesn't preclude the fact that every filter causes phase shift. Its effect at the listening position may be helpful or it may be harmful.
> 
> 
> Certainly, it will do its best to smooth the response at the crossover to account for any cancellation caused by phase shift. This is one of the reasons you find Audyssey sub distance values being so far from actual - it uses time (distance) to shift the phase at the point of measurement. So, it's always best to set your BFD filters for the sub before running Audyssey. In addition, Audyssey does a far better job when it doesn't have large compensations to make.
> ...


Good that we agree :T


corock said:


> Thanks for all the help.
> 
> The amount of time you experienced guys put in to help us newbies is amazing. It's very much appreciated. Put me down as a platinum supporter, its a deal for all the tools and support I've received from this forum. I'll be sure to revive this thread with measurements of the results I get from your advice.:bigsmile:


Thats what we're here for, be sure to update us on the results.


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

corock said:


> Is it possible my BFD is causing a phase shift?


As others have noted, all IIR filters create phase shift, but it's not a bad thing. In fact phase shift is why equalizers work. See this article.

Regards,
Wayne


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## corock (Sep 7, 2009)

I see from the article that an equalizer causes a phase shift at the frequencies where the filters are placed. But can it put the subs completely out of phase with the mains as may be my case.


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## JohnM (Apr 11, 2006)

corock said:


> I see from the article that an equalizer causes a phase shift at the frequencies where the filters are placed. But can it put the subs completely out of phase with the mains as may be my case.


No. The phase shift from peaking filters goes to zero as you get further from the filter centre frequency.


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## Moonfly (Aug 1, 2008)

JohnM said:


> No. The phase shift from peaking filters goes to zero as you get further from the filter centre frequency.


I think that nicely puts us at the point of the differences between electrical and mechanical phase (speakers could be mechanically out of phase, but electrically in phase, and vice versa etc). I dont think there is really any point tough, as long as corock uses REW to get his response where he wants it, thats all that really matters here.

There are many things that affect the phases in your system. The poles on your speakers, the distances they are from each other, and the devices in your system that causes delays to signal timing. No matter what you do in your system, the target is that flat response, and once achieved your whole system will be as in phase as it can be, or rather as it needs to be. Focus on getting the response to where you want it, if the graph shows glaring phase issues then you can react to solve those, if not, then there need be nothing more to worry about as long as you like the resulting sound.


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## corock (Sep 7, 2009)

Well here it goes...

Moonfly, your advice to tune the subs seperately was spot on. I have one at 10hz and the other at 15hz. That flattened out the response a lot and got rid of the spl drop at 40hz that Tony pointed out as a weak spot in my setup. 

My base line measurements before running Audyssey showed my subs and mains playing nicely and reinforcing each other. After running Audyssey things weren't so great anymore. I was losing spl on either side of the cutoff again. I adjusted the phase and found it was out pretty much 180 degrees when Audyssey was applied. 

Here's my final measurements. I put in only 1 filter with the BFD, a cut in the 30-40hz area, then applied Audyssey.









Let me know if you see any problems I need to address. 

And here's a waterfall of the subs. I don't know much about this and I'm not sure I'm ready to open this can of worms.


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## laser188139 (Sep 19, 2009)

I'm glad you were able to fix the phase issue at the sub. 

Am I reading the graphs correctly? It appears the purple is the mains alone, the gold is the sub alone, and the teal is the combined graph? That seems to indicate that the crossover is now set around 150Hz. If so, that would seem a little high. Most advice indicates that the subs may become localizable when the crossover is above 80Hz. Of course, as you have two of them and they are probably symmetrically situated, this may not be an issue for you. And it may be that you have done this to let the subs cover the null in the main response around 120Hz, probably from a reflection off the front wall or a corner. How does it sound with the crossover set that high?

There is a good chance that the 60Hz resonance it the waterfall is an artifact of your computer. Several people have found this to be true. When I tried disconnecting my laptop from the AC power and rerunning the measurements, the 60Hz lump in the waterfall disappeared for me, too. 

Bill


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## corock (Sep 7, 2009)

actually the crossover is set at 80hz, the lfe is set to 120. 100% the crossover for fronts and surrounds is set to 80hz and LFE is set to 120hz. Double checked and crossover on sub amps are turned off. I don't know whats causing them to crossover way out there.


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## Moonfly (Aug 1, 2008)

Set LPF of LFE to 80hz and that should bring your crossover down. Also, did you apply the octave smoothing to your graph?

How is it sounding compared to before?

The graph isnt looking bad at all now, and as bill said with 2 subs a high crossover isnt as much of an issue as usual so its less of a concern than it might normally be.


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## laser188139 (Sep 19, 2009)

corock said:


> actually the crossover is set at 80hz, the lfe is set to 120. 100% the crossover for fronts and surrounds is set to 80hz and LFE is set to 120hz. Double checked and crossover on sub amps are turned off. I don't know whats causing them to crossover way out there.


Just to show you why I'm a little perplexed by your graph, then, here is a comparable one from my system. There is only one sub (green), the left (dark blue) and right (light blue) fronts were measured separately, and the overall combined line (red) shows the three added together. 









Looking at my graphs, you can do a little smoothing with the eye and imagine that the two mains are showing the crossover filter dropping off at about 12dB per octave from a little above 80, and the sub is dropping off at 24dB per octave starting a little below 80. 

Your graph is more of a puzzle. The lines together make sense, in that above 150Hz the combined line tracks the main alone, and below that point the combined line tracks the sub alone. So the measures all appear to be taken at the same time with the same calibration. If the crossover is set at 80Hz, I could imagine seeing that in the main graph as it drops off about 24dB in the octave from 80Hz to 40Hz. The trend line of the sub is not quite as obvious, but perhaps there is a 24dB drop from the peak a little below 80Hz to about 160Hz. So I am left with two hypotheses. One, that you tweaked the sub trim up in the receiver after running Audyssey because you want more content in the bass. I find this hypothesis doubtful as you are spending a lot of effort to make this system even. Two, that Audyssey has set the sub level and the main level for the right overall average, but that even with its equalization the mains response is lower here below 200Hz (and higher somewhere else in the range), so that the subs are carrying the load well above the configured crossover. It's curious, and a puzzle, one learns something new about Audyssey all the time. Which version is in your receiver? MultEQ? or MultEQ XT? With two subs you probably won't hear any localization. And, as I said earlier, your graph nicely covers whatever near wall effect you have on the fronts. (And you can see I have similar issues with my front L/R placement giving a dropout around 130Hz.) 



Moonfly said:


> Set LPF of LFE to 80hz and that should bring your crossover down. ...


Changing the LPF for LFE should have no effect on the apparent crossover, as the cabling for testing drives just the front left and right and there is no LFE content during measurement. 

As regards the waterfall, I would expect the resonances at 31Hz and 38Hz correspond to room dimensions, 18ft or 36ft for 31Hz, 14.8ft or 29.6ft for 38Hz. Looking back it appears your subs are each corner loaded. I doubt that changing the location of the subs would affect the modes much, and I expect Audyssey in the receiver handles two subs much better when they are located symmetrically, equidistant from the first measurement point. 

Did you ever mention which microphone you are using? I'm not sure whether the waterfall response at 15Hz could be an issue, but if your calibration file is not specific to your physical mic the measurements there may not be reliable. In my environment, if I drive that "room mode" it is really a mode of the house between the exterior walls, and I start shaking things off walls in other rooms. 

Bill


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## brucek (Apr 11, 2006)

> so that the subs are carrying the load well above the configured crossover.





> That seems to indicate that the crossover is now set around 150Hz.


It doesn't appear to me that the crossover is that far off. :huh:

I overlayed sub crossovers onto his graph until one matched, and the best fit was 90Hz as shown below. I think a bit of Audyssey filtering could account for the amount it's above 80Hz?










brucek


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## corock (Sep 7, 2009)

Bill I think you hit it on the head. I did increase the sub trim after I ran Audyssey. While balancing my subs I found a nice balance of the sub gains and the avr trim at -4.5 that allowed me to run my subs at volumes I prefered without digitally clipping them. When I ran Audyssey it cut the trim (because my subs were hot) to -12. So I manually increased the trim back to -4.5. But, I guess since -12 is the max cut I should rebalance the subs with lower gains and get Audyssey's trim level back inside the limits before I manually make adjustments. I just find that by lower the gains I have to increase the trim to a level that cause digital clipping earlier than I would prefer.

There is no smoothing on the graphs and I'm using a RS meter


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## laser188139 (Sep 19, 2009)

brucek said:


> ...
> 
> I overlayed sub crossovers onto his graph until one matched, and the best fit was 90Hz as shown below. I think a bit of Audyssey filtering could account for the amount it's above 80Hz?
> ...
> ...


That's a nice curve, brucek. I'm sure it is a rather naive expectation on my part, that after applying the crossover filter to the mains and subs at 80Hz, one would see the response curves of the main and sub cross over each other somewhere near that 80Hz frequency. A naive expectation encouraged by the fact that the measurements on my system match it. So I'm naturally curious when that's not what I see in another system, where the measured responses cross over almost an octave higher. And I look for explanations, even when the overall response may be fine, as in this case. 

Bill


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## laser188139 (Sep 19, 2009)

corock said:


> ... So I manually increased the trim back to -4.5. ...
> 
> There is no smoothing on the graphs and I'm using a RS meter


Thanks for clarifying. Yes, I would try to get the gains set where Audyssey is off its -12dB lower limit, just so you know its level setting is right before any custom adjustments. 

When I compared it to my EMM-6, I found my RS meter had a response below 20Hz, esp. below 15Hz, that differed from the sample calibration file. So unless you are hearing something there, I would discount the 15Hz lump in your waterfall as perhaps not as large as it seems. 

Bill


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## brucek (Apr 11, 2006)

> expectation on my part, that after applying the crossover filter to the mains and subs at 80Hz, one would see the response curves of the main and sub cross over each other somewhere near that 80Hz frequency.


I do think they would cross fairly close to 80Hz if you visualize raising the mains in the jpg above about 5-8dB and ignore the rather large dip the mains are suffering from at ~120Hz.

Certainly, the actual crossover point (regardless of the set point) is highly dependent on the relative levels between the mains and sub, and I agree that's the case here. The mains are simply lower than the sub in level, so the crossover mix point moves up in frequency.

brucek


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## corock (Sep 7, 2009)

brucek said:


> the actual crossover point (regardless of the set point) is highly dependent on the relative levels between the mains and sub
> brucek


I see how the crossover would move left and right as the sub level increased or decreased in relation to a constant mains level. So that's not really a problem, just a result of my listening preferences and something thats a variable and will change as I experiment with the levels.


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## brucek (Apr 11, 2006)

> So that's not really a problem


Well, it may not be accepted practice though, but if you like the sound, that's what's really important. 

Let me suggest another method.

Generally, as Bill so wisely pointed out, you would like a crossover point to be where you've actually set it. This way you set the mains and sub to equal levels and they cross at the set point.

The accepted method to increase your bass is to add a house curve.

Look at the jpg below of a mains and sub target overlayed, as it demonstrates that an 80Hz crossover set point will result in an actual measured 80Hz crossover if the levels are maintained as equal.


*MAINS & SUB at 75dBSPL with 80HZ CROSSOVER*










Now examine the jpg below and see what happens (as evidenced by your method) when you have a 80Hz crossover and the mains are dropped by 8dB below the subs level to 67dB.
See how the 80Hz set point has moved to ~100Hz.


*MAINS at 67dBSPL & SUB at 75dBSPL with 80HZ CROSSOVER*










Now see what happens when I maintain both sub and mains at 75dB and add a 8dB house curve to the sub. I maintain the 80Hz actual mix and I have increased the subs level.


*MAINS & SUB at 75dBSPL with 80HZ CROSSOVER with HOUSECURVE*








Something to think about anyway. 


brucek


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## corock (Sep 7, 2009)

I absolutely agree with you Bruce. I've done a lot of experimenting with house curves and would prefer to go that route. I guess the issue I've have trouble wrapping my head around is...if I create a house curve with the BFD then apply Audyssey after (as has been recommended), isn't audyssey seeing the higher levels as a peak that needs to be flattened, there by counteracting the filters I've created with the BFD?:scratch:


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## brucek (Apr 11, 2006)

> ...if I create a house curve with the BFD then apply Audyssey after (as has been recommended), isn't audyssey seeing the higher levels as a peak that needs to be flattened, there by counteracting the filters I've created with the BFD?


Yes, it could, and I've played around with that on one of my systems and it didn't appear to matter. The house curve doesn't offer any level change at the crossover frequency, and slowly adds level as it lowers to 30Hz. I see no effect in my Denon Audyssey from having a house curve, but then, that's a sample of one and hardly conclusive. 

brucek


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## corock (Sep 7, 2009)

Okay then, thats the next project. I'll lower my sub levels, balance them with the mains, apply a house curve, then run Audyssey and see what the outcome is. I find this hobby very similar to golf. Just when you think you've figured it out, you discover you're not any better then you were before. I guess that's what makes it addicting for me...trying to conquer the unconquerable.


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## laser188139 (Sep 19, 2009)

corock said:


> I absolutely agree with you Bruce. I've done a lot of experimenting with house curves and would prefer to go that route. ...


Of course, Audyssey receivers since last year will do something like this for you when DynEQ is enabled, at anything less than reference levels. One can get some idea of what it is doing by measuring at different master volume levels. But this is only an idea, as apparently it compares the master volume level to reference, and compares the actual content level to reference to determine how much adjustment to make.


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## corock (Sep 7, 2009)

laser188139 said:


> Audyssey receivers since last year will do something like this for you when DynEQ is enabled, at anything less than reference levels. .


My AVR is using MultiEQ XT and has DEQ. I like the effect it has at lower listening levels. For my preference as I approach reference level and DEQ reduces its affect I don't have as much bass as I would like, which is why I run my subs hot. If I didn't listen to music so loud I would actually just be happy with just relying on DEQ.


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## Moonfly (Aug 1, 2008)

corock said:


> I absolutely agree with you Bruce. I've done a lot of experimenting with house curves and would prefer to go that route. I guess the issue I've have trouble wrapping my head around is...if I create a house curve with the BFD then apply Audyssey after (as has been recommended), isn't audyssey seeing the higher levels as a peak that needs to be flattened, there by counteracting the filters I've created with the BFD?:scratch:





brucek said:


> Yes, it could, and I've played around with that on one of my systems and it didn't appear to matter. The house curve doesn't offer any level change at the crossover frequency, and slowly adds level as it lowers to 30Hz. I see no effect in my Denon Audyssey from having a house curve, but then, that's a sample of one and hardly conclusive.
> 
> brucek


Ive not really played with house curves myself, but will do when I finish building my DIY effort. Has anyone noticed any adverse effects from applying a house curve after Audyssey has completed setup.



corock said:


> My AVR is using MultiEQ XT and has DEQ. I like the effect it has at lower listening levels. For my preference as I approach reference level and DEQ reduces its affect I don't have as much bass as I would like, which is why I run my subs hot. If I didn't listen to music so loud I would actually just be happy with just relying on DEQ.


Have you tried the double bass setting. It gives more bass without upping the subs etc, and you might find you like the sound of it, always worth an experiment anyway.


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## corock (Sep 7, 2009)

All the house curves I've experimented with have been applied on top of Audyssey. I've never done a house curve then Audyssey so I don't have anything to compare it too. I'll probably try both...now that I've been able to flatten my response lots by having the subs at different tunings I don't think Audyssey is changing the frequency response much anyway. But I don't know what type of effect it would have on Audyssey's time and space settings...I'm still trying to get a handle on a simple FR measurement. 

I did use double bass when I was using a single Paradigm PS-1000 subwoofer. After reading about all the "evils" of double bass that's when I got serious about subwoofers and made the move to the SVS duals. I have not listened in double bass mode since I got the Ultras. I don't know how much impact it would have since the drivers in the Paradigm Millenias are quite small, however there are twenty of them.


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## Moonfly (Aug 1, 2008)

To be honest Ive tried just about every setting possible (other than applying house curves, I used the Ultras tune modes to effectively apply the same thing whilst incorporating Audyssey as well), and while I occasionally find DB fun, other times I dont.

I eventually concluded that no single configuration in the amp worked for everything, and forced myself to come to terms with that. I simply had to find what I thought was the bet all round sound musically.


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## corock (Sep 7, 2009)

Moonfly said:


> I eventually concluded that no single configuration in the amp worked for everything, and forced myself to come to terms with that.


I hear you. I'm in the same boat and realize I will have to make a compromise somewhere. For instance I would like to do without Audyssey all together, but I really like how it warms up my mains, which I find to be "cool" in my room. I'm prepared to do lots of experimenting and actually look forward to it.


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## corock (Sep 7, 2009)

I did a little experimenting on today and here's what resulted. This first graph is my attempt to create a house curve with BFD then run Audyssey afterwards. The blue line is the house curve pre-Audyssey and the red line is post-Audyssey. I think that experiment was a failure.









Then I tried running Audyssey then putting a house curve afterward with BFD. The green line is the subs, blue is the mains and red is full range. This looks better to me, it definately sounded better. It looks to me like the mains and subs cross over at 80hz like they're set to, but then the subs peak from 90hz to 150hz, while the mains dip in the same range.









I was thinking of knocking that 120hz peak down with BFD, but it seems the sub is carrying the sound there because the mains drop off significantly. I might try that with a seperate set of filters and compare the two


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