# Subwoofer with AVR Audyssey XT32 setup



## roger1014 (Oct 18, 2011)

I have 2 Polk Audio DSWmicropro 2000 subwoofers and a Denon 4311ci AVR. The subs have a mike, that is connected to sub, which is used for the "Autopro Room Resonance Correction" and the Denon uses the "Audyssey MultEQXT32" for speaker calibration. 
Which, or do I use both, do I use when adding the subs to my system. If I first perform the Auto pro on the subs and then use the Audyssey on the AVR, Audyssey reports the subs as being about 31 feet away while the actual distance is 11 feet. Polk advised me to first calibrate the subs but not to include the subs when doing the Audyssey for the rest of the speakers. If I do it that way, I am concerned that Audyseey will not blend the sound of the subs with the rest of the system.....
Any thoughts .....?


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## sdurani (Oct 28, 2010)

Audyssey MultEQxt32 on your Denon 4311 includes their Sub EQ HT feature, which calibrates (sets levels & distances for) each sub independently but equalizes their response together (since that's how you'll be hearing them anyway). 

Can the resonance correction in your Polk subs correct for the combined response of both subs? If not, then you'll be correcting for something you'll never hear: only one subwoofer. For example: suppose you placed your subs on the midpoints of opposite walls. When correcting one sub, you notice a resonant peak, so you pull it down. Turns out the sub on the opposite wall would have cancelled that room resonance when both subs were on. Pulling down the peak has now created a dip in the combined response. 

It doesn't make sense to correct each subwoofer separately, when you'll never be hearing them that way. Better instead to let Audyssey handle it, by EQing both subs together. Personally, I wouldn't bother with the room resonance correction built into the Polk subs.


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## tonyvdb (Sep 5, 2007)

Speaker distance is not necessarily set to actual distance but is also a delay adjustment Lower frequencies travel slower than higher frequencies so Audyssey compensates for that difference by adding longer delay so the lower frequencies from the sub reach the listening area at the same time as the rest.


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## roger1014 (Oct 18, 2011)

Thanks Sanjay, never thought about it that way but it does make some sense when using 2 subs...


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## sdurani (Oct 28, 2010)

tonyvdb said:


> Lower frequencies travel slower than higher frequencies


I thought the only things that affected the speed of sound were temperature and the medium it is traveling through. Are you sure that frequency affects the speed of sound?


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## tonyvdb (Sep 5, 2007)

That is true however the lower frequencies are affected less by furniture and walls so it can arrive at different times at the listening position. Im no expert in this area so I hope someone can clear this up a bit better.


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## sdurani (Oct 28, 2010)

tonyvdb said:


> lower frequencies are affected less by furniture and walls


I thought that was true of higher frequencies: since they are more directional, they are less affected by walls compared to lower frequencies (which are relatively omnidirectional and bouncing off everything). Hopefully someone can clear this up.


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## roger1014 (Oct 18, 2011)

I knew I read this before .....from the Audyssey website

If you have a subwoofer with room EQ, then you should run that first in the subwoofer and then run MultEQ in the AVR.


If you have an external subwoofer processor (such as the SVS AS-EQ1 or the Audyssey Sub Equalizer) you should run the calibration in that processor first and then run MultEQ in your AVR

If you have two subwoofers, there are some additional steps to take:


1.Place them at equal distances from the main listening position
2.Set the level controls on the back so they both play at the same level
3.Connect a y-cord to the sub out of the AVR and then connect to both subs
4.Turn off processing in the subs as it will not be able to give you the same resolution that you will get from MultEQ (thousands of points vs. a few parametric bands)

If you wish to use the calibration systems in any of the subs, you should do that first before running Audyssey. Please be aware that digital processing in the subs introduces additional signal delay. So, when you run MultEQ the reported delays/distances for such subs will be longer than the physical distance. This is normal and is part of the correction that MultEQ performs to make sure that signals from all speakers and subs are arriving at the main listening position at the same time.


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## sdurani (Oct 28, 2010)

roger1014 said:


> I read this before .....from the Audyssey website
> 
> If you have two subwoofers, there are some additional steps to take:
> 
> ...


1. Not necessary to place them at equal distances from your main listening position, since the two subwoofer outputs on your Denon 4311 can set distances and levels independently, so it is OK to have subs at different distances. (That's an awesome receiver.)

2. There is a valid case to be made that it is better to set the level knob on the back of the subs to the same gain, not the same level. Depending on the placement of your subwoofers and the shape of the room, subwoofer A might be getting more reinforcement from room boundries than subwoofer B, making sub A sound louder than sub B. If you want to level match them, sub A will have to be turned down a bit while sub B will have to be turned up a bit. This means the amp in sub B will run out of headroom before the amp in sub A. 

The alternative is to gain match your subs. Place sub A in the middle of your room, turn its gain knob to the middle position and measure with your SPL meter from a couple inches away. Without moving the meter, replace subwoofer A with subwoofer B, at the exact same location, pointing the exact same direction. Move the gain knob till you get the same SPL reading as you did for sub A. Now both amps are set to the same gain and will have the same amount of headroom. 

3. No need to use a Y-connector since your Denon already has 2 subwoofer outputs. (Did I mention it's an awesome receiver.)

4. The only time I would use the EQ built into the subwoofer AND room correction in the receiver together is if I was using a single sub AND correcting for a single seat. For all other situations, I would stick to the room correction in the receiver, since it will take into account multiple subs and/or multiple seats.


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## roger1014 (Oct 18, 2011)

My subs do not have gain control dials ...they use a remote control to adjust the level . Questtion .... is "level" the same as "gain"? I can adjsut the level with the remotes, for the sub, or with the menus in the Audyssey of the AVR. Also, when using the Audyseey setup, and if the sub level is too high or too low, the program will tell me I need to adjust sub level control to about 75db...Audyssey will display a picture on my monitor indicating weather the out of the sub is too low or high and then I can monitor that display while I manually adjust the sub level.


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## sdurani (Oct 28, 2010)

roger1014 said:


> Questtion .... is "level" the same as "gain"?


Not in the context of what I was discussing. "Gain" in this case has to do with how much the amplifier is boosting the signal. "Level" is how loudly you hear it. 

If you place two subs, one in a corner and the other in the middle of the room, then the one in the corner will be louder because it is getting boundry reinforcement (from 2 walls and a floor). If you level match them, then the subwoofer amplifier in the middle of the room will have to be set higher (work harder) to get the same level as the sub amp in the corner. When there is a loud passage, the subwoofer amp in the middle of the room will run out of power and distort much sooner than the one in the corner. 

As I mentioned, the alternative is to gain match them. Before placing your subs, put them one at a time at the same location and use a SPL meter a few inches away to set their level. Since they are producing the same level, at the same location, to a meter the same distance away, their amps will be working equally. If you place one in a corner and the other in the middle of the room they will be at different levels but, since both amps are working equally, they will both run out of headroom at the same time. 

Use whichever method you prefer. Some swear by one or the other. I just wanted to let you know that there are two alternatives.


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## ItsADucati2012 (Dec 26, 2012)

I have 2 subwoofers as well. Each of them have their own amplifier,which does not use power from the receiver. It took a long time to get the exact bass sound I was looking for. Also depends how big the room is and what the walls are made of. Also insulation and the height of ceiling is another issue. This is what I have seen on this forum which people always have a issue about the material on the walls such as carpet or other material.


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