Two Subs with different Settings

[Richx200]

For the past few days I have been working on a Null and I think I have the problem solved. I think the graph looks good, the bass sounds much better, and I have headroom on the subs. The problem is that the settings made by ARC Genesis are inconsistent with the material I used to get rid of the Null.

Floyd Toole's book Sound Reproduction in Chapter 8 page 262 he states: "When measurements are done it is common for some individuals to try equalizing each sub separately and then combine them. Again, disappointment is almost always guaranteed because when the system is in "play" mode all subwoofers are operating simultaneously, and the results of the acoustical summation is unpredictable. The measurement that matters is the one of all subwoofers operating simultaneously. For individually measured subwoofer outputs to sum in a predictable manner ; the measurements must be the transfer function - amplitude and phase - not the steady - state amplitude response. This is the basis of room mode manipulation schemes described in Sect. 8.2.7-."

Arc Genesis didn't follow Toole and produced the these settings:

3db difference between sub 1 and sub 2

SUBWOOFER 1
Subwoofer Crossover Frequency (or Low-Frequency Extension): 80 Hz
High-Pass Frequency: 15 Hz
High-Pass Slope: Flat
Minimum Correction Frequency: 15 Hz
Phase Filter: 120 degrees @ 80 Hz

SUBWOOFER 2
Subwoofer Crossover Frequency (or Low-Frequency Extension): 160 Hz
High-Pass Frequency: 16 Hz
High-Pass Slope: 10th
Minimum Correction Frequency: 15 Hz
Phase Filter: 0 degrees @ 80 Hz

Overall, I would say ARC did a good job, but I don't understand how or why the two subs could be so far apart?

 

[win]

but I don't understand how or why the two subs could be so far apart?

These optimization algorithms are all non-deterministic. You could rerun it, and get a result you feel better about.

 

[Richx200]

These optimization algorithms are all non-deterministic. You could rerun it, and get a result you feel better about.

These are the settings ARC Genesis wants to load into the AVR. I do realize that I wouldn't get the same readings on a rerun, because exact mic placement is unlikely.

 

[Beershaun]

It's hard to say without understanding the model of each sub and their position in your room. I am surprised by the crossover point being so different. Are they different models? I would think it would be hard to get a consistent frequency response between 80 and 160hz since effectively only one sub is running in that range. Regarding phase that has more to do with blending the sub with the front speakers at the crossover point. And so again since they are so different then the phases will be different. Also they relative location to the main speakers and listening position will affect phase as well.

If you want to follow Floyd tooles instructions you will need to use REW and take measurements with both subwoofers running together at the same time once they have been calibrated individually by ARC. Then you can manually try to tweak your ADC settings.

 

[Richx200]

It's hard to say without understanding the model of each sub and their position in your room. I am surprised by the crossover point being so different. Are they different models? I would think it would be hard to get a consistent frequency response between 80 and 160hz since effectively only one sub is running in that range. Regarding phase that has more to do with blending the sub with the front speakers at the crossover point. And so again since they are so different then the phases will be different. Also they relative location to the main speakers and listening position will affect phase as well.

If you want to follow Floyd tooles instructions you will need to use REW and take measurements with both subwoofers running together at the same time once they have been calibrated individually by ARC. Then you can manually try to tweak your ADC settings.

Thank you for your response

I posted two graphs, one from quick measure ARC, which shows the null I was trying to smooth out. The second graph is from REW (both speakers) with the calibrated ARC settings, the null looks corrected, and the subs sound a little lean.

I'm using two SVS 13 Ultra with the 1200 watt amp upgrade. One sub is located left front facing back, the other right back turn 45deg toward the front sub. These were the best positions I could get to work out the null.

 

[Beershaun]

Thanks. Looks like youve addressed the problem. I would then just use those settings manually. Since your subs are in very different locations relative to your listening position and to your front main speakers I would expect them to be very different. The one thing I think still looks odd is the 150jz crosser. That seems very high. I'd expect it to be somewhere closer to 80-100 depend on your mains. Unless it's being used specifically to address a room mode between 100-160hz.

 

[Richx200]

Thanks. Looks like youve addressed the problem. I would then just use those settings manually. Since your subs are in very different locations relative to your listening position and to your front main speakers I would expect them to be very different. The one thing I think still looks odd is the 150jz crosser. That seems very high. I'd expect it to be somewhere closer to 80-100 depend on your mains. Unless it's being used specifically to address a room mode between 100-160hz.

I think you are right, the difference is probably due to a room mode correction.

Now that I have the settings saved on the AVR, I think I'll play with them for a while to see what I get. Can always reload the master.

Again, thank you for your response.

 

[Fredygump]

For the past few days I have been working on a Null and I think I have the problem solved. I think the graph looks good, the bass sounds much better, and I have headroom on the subs. The problem is that the settings made by ARC Genesis are inconsistent with the material I used to get rid of the Null.

Floyd Toole's book Sound Reproduction in Chapter 8 page 262 he states: "When measurements are done it is common for some individuals to try equalizing each sub separately and then combine them. Again, disappointment is almost always guaranteed because when the system is in "play" mode all subwoofers are operating simultaneously, and the results of the acoustical summation is unpredictable. The measurement that matters is the one of all subwoofers operating simultaneously. For individually measured subwoofer outputs to sum in a predictable manner ; the measurements must be the transfer function - amplitude and phase - not the steady - state amplitude response. This is the basis of room mode manipulation schemes described in Sect. 8.2.7-."

Arc Genesis didn't follow Toole and produced the these settings:

3db difference between sub 1 and sub 2

SUBWOOFER 1
Subwoofer Crossover Frequency (or Low-Frequency Extension): 80 Hz
High-Pass Frequency: 15 Hz
High-Pass Slope: Flat
Minimum Correction Frequency: 15 Hz
Phase Filter: 120 degrees @ 80 Hz

SUBWOOFER 2
Subwoofer Crossover Frequency (or Low-Frequency Extension): 160 Hz
High-Pass Frequency: 16 Hz
High-Pass Slope: 10th
Minimum Correction Frequency: 15 Hz
Phase Filter: 0 degrees @ 80 Hz

Overall, I would say ARC did a good job, but I don't understand how or why the two subs could be so far apart?

I don't know about how ARC works, but I would rather manually optimize subs because then I actually know what is happening.

Floyd Toole says that a speaker with a flat anaechoic response is what sounds the best. If this is true, than an optimization system that tries to fix in room response is changing the anaechoic response. These systems are all the rage, but they also contradict Floyd Toole.

The subwoofer part is a rabbit hole as deep as you want it to go, but if you are interested you can optimize subs yourself with REW and a MiniDSP unit. I've done this on my DIY speakers. The one thing I'd say is that if you choose DIY, I would feed both subs from the same sub output. That way the optimization can't un-do the manual work you did.

There are a few methods to use. There is the MSO program that may work for you. The "optimization" I've had success with is using delay (i.e. time alignment) to change the phase interaction of the subs. It has the same effect as moving subs around the room.

Sub optimization is cool, but it isn't always necessary. It depends on your room. I found that in my system and my room/ house, a generic stereo sub configuration, with one sub inverted, is almost as good as what I got from hours of fine tuning and experimenting.

 

[Richx200]

I don't know about how ARC works, but I would rather manually optimize subs because then I actually know what is happening.

Floyd Toole says that a speaker with a flat anaechoic response is what sounds the best. If this is true, than an optimization system that tries to fix in room response is changing the anaechoic response. These systems are all the rage, but they also contradict Floyd Toole.

The subwoofer part is a rabbit hole as deep as you want it to go, but if you are interested you can optimize subs yourself with REW and a MiniDSP unit. I've done this on my DIY speakers. The one thing I'd say is that if you choose DIY, I would feed both subs from the same sub output. That way the optimization can't un-do the manual work you did.

There are a few methods to use. There is the MSO program that may work for you. The "optimization" I've had success with is using delay (i.e. time alignment) to change the phase interaction of the subs. It has the same effect as moving subs around the room.

Sub optimization is cool, but it isn't always necessary. It depends on your room. I found that in my system and my room/ house, a generic stereo sub configuration, with one sub inverted, is almost as good as what I got from hours of fine tuning and experimenting.

I think Toole was talking about equaling speakers above the transition, because equaling above 200-250Hz changes the character of the speaker. I always run my speakers flat above 300Hz. Subwoofers really see anything above 80Hz, and the room is the hardest part to get right.

 

[Fredygump]

I think Toole was talking about equaling speakers above the transition, because equaling above 200-250Hz changes the character of the speaker. I always run my speakers flat above 300Hz. Subwoofers really see anything above 80Hz, and the room is the hardest part to get right.

Yes. I was referring to room correction systems in general. I'm guilty as charged of tweaking low frequency response.