SVS pb12-ultra unfulfilled

[Hostility]

here are the other plots, phase is set to 0 (were not when arc was ran) distances are accurate in arc.

my room is 1200sq ft. 16ft long, 11ft wide 7' ceiling. Im hopefully getting my serial to usb adapter tomorrow so i can run arc.

Do you think 2 of the smaller svs sealed subs would be suffice? (dual sb12-nsd) if not then i would go with the pb12-plus with front firing ports.

 

[agarwalro]

Using the room dimensions, the modal frequencies are, 35.3, 51.4, 62.3, 70.6, 80.7, 87.3, 88.1, 95.7, 102.0 Hz and on. You can see a longer list using this calculator.

So lets take a closer look at LR and sub plots.

Sure enough, the locations of peaks and dips across the three more or less fall on the aforementioned frequencies. Further, since the LR are on one boundary and your listening position is at the other, combined with the frequencies being so tightly grouped, you are getting that wide hump in L (40-100Hz) R (25-90Hz). Try playing around with pulling the speaker out a little and move your couch further away from the wall. This should reduce the intensity of the peak.

The location of the sub compared to the listening position is exciting the frequencies silghtly differently than the LR. That is why it is creating a similar hump with a suckout at 42Hz and 70-120Hz. Note that the LR have a corresponding suckout, but not as intense.

Since your calculated curves have not been applied , this perfectly explains why you are underwhelmed with the sub. Try the sub in the left corner and measure it again. Maybe it will turn out better.

I would say that your room is a prime candidate for broadband bass traps and tons of them on the ceiling-front wall and ceiling-back wall corners.

 

[lsiberian]

Try raising your receivers sub and speaker crossover up to at least 100 and see if that helps. It looks like you have problems down low with those speakers from the graphs.

 

[Hostility]

Thank you for the last 2 posts, i will try to take this all in (a bit hung over and cant think straight). What do you mean when you say "Since your calculated curves have not been applied"? I have ran arc with the sub in its orig spot and applied it. Now when i tested the sub in 3 different spots i didnt remeasure as i still dont have my cable yet. Do you think its worth a shot measuring it in all 4 (i can do a quick measure and post the graphs). I have done some changes to room and speakers so i will have to remeasure for those (took a dvd shelf off the wall, new computer desk, great gamma, pulled the speakers out more to hopefully help with wider sound stage). If it helps at all i can give you the measurements of my room and how far the speakers are from the wall etc.

also on a side note. Because the ports are 10" from the wall, do you think front firing ports would benefit me?

 

[agarwalro]

What do you mean when you say "Since your calculated curves have not been applied"? I have ran arc with the sub in its orig spot and applied it... Now when i tested the sub in 3 different spots i didnt remeasure as i still dont have my cable yet.

I kept getting thrown off by your not having the cable. I looked up how Anthem ARC works. Evidently it cannot be done without the RS232 cable hooked up at the back of the receiver. I assume you are doing this via the PC's serial port and want to use the laptop USB instead? I apologize for the confusion. I think I'm on it now .

Now when i tested the sub in 3 different spots i didnt remeasure as i still dont have my cable yet.

So, do you mean you just listened for more pleasing sound? Like standing in front of the TV sounds better vs. sitting on the couch.

Do you think its worth a shot measuring it in all 4 (i can do a quick measure and post the graphs). I have done some changes to room and speakers so i will have to remeasure for those (took a dvd shelf off the wall, new computer desk, great gamma, pulled the speakers out more to hopefully help with wider sound stage).

Since you have made changes to the room, it is mandatory to remeasure.

If it helps at all i can give you the measurements of my room and how far the speakers are from the wall etc.

You gave the dimensions earlier (alcohol induced memory loss ) and I don't think having the speaker distances down to the inch will help me better visualize the room. The FR is more than sufficient for this discussion.

Because the ports are 10" from the wall, do you think front firing ports would benefit me?

I think it is far enough. I've had mine as close as 4-5" from the wall and did not hear the port chuff (meaning, port was not restricted form normal airflow needs). It becomes something to worry about if you have it too close (like 1-2") since it could effectively changes the port tuning.

 

[Hostility]

I kept getting thrown off by your not having the cable. I looked up how Anthem ARC works. Evidently it cannot be done without the RS232 cable hooked up at the back of the receiver. I assume you are doing this via the PC's serial port and want to use the laptop USB instead? I apologize for the confusion. I think I'm on it now .

So, do you mean you just listened for more pleasing sound? Like standing in front of the TV sounds better vs. sitting on the couch.

Since you have made changes to the room, it is mandatory to remeasure.

You gave the dimensions earlier (alcohol induced memory loss ) and I don't think having the speaker distances down to the inch will help me better visualize the room. The FR is more than sufficient for this discussion.

I think it is far enough. I've had mine as close as 4-5" from the wall and did not hear the port chuff (meaning, port was not restricted form normal airflow needs). It becomes something to worry about if you have it too close (like 1-2") since it could effectively changes the port tuning.

Yea sorry, my old pc had serial, new one doesn't so i was able to run arc when i first got it, but since then built a new pc, so desperately waiting for this cable lol

I haven't re-ran arc yet as i knew i was doing a few changes so i waited till they were all done.

As for testing in 3 spots, i tired moving the sub beside both mains and to the opposite side of the couch (so i have 4 spots total) each time i tested with a movie. Up front beside my main i got tons of that more up top bass, and boom, but for movies i lost my low end shake, i couldn't tell if the subwoofer was doing anything, but beside my couch it just ripples through it so i can feel what its doing.

 

[agarwalro]

When EQ doesn't work

A FR plot does not show the complete picture. It does not show how the sound energy dissipates over time. A better way to visualize this is via spectral decay plots, aka. waterfall plots. A standard guideline in laymen terms can be stated as, "the room should significantly dissipate sound energy in half a second". In technical terms, T20 less than 150ms and T60 between 200-500ms.

The modal frequency peaks are representative of the room reverberating with sound energy well past speaker having stopped that sound. Conversely, the dips represent excessively damped frequencies, which is beneficial as long as the listening position is not in a null. As one might imagine, using EQ to lower the peaks will help somewhat. It will lower the initial amount of energy injected into the room at that frequency, but it does nothing for how quickly the sound dissipates. EQ-ing a dip is of no use whatsoever. You can add more and more energy to the frequency, it will simply cancel out and leave the null unchanged. If you elevate the overall signal level, you have an ever deepening null compared to the average signal level.

ARC is simply applying a very complicated EQ to your system. As mentioned, EQ will not fix room issues. So, even though the ARC plots in green trace lead you to believe the speakers are closely following the target curve, that is far from the reality of the situation.

More on spectral decay and waterfall plots here.
More on room acoustics and modal frequencies, here and here and a video here.
Excellent video on how room treatment help. Jump to about 3:30 in the video to see measured results.

The final word on good bass, here.

 

[Hostility]

Thanks for all the links, ive read through about 3/4 of them, but have a bit of a hard time trying to understand all of this. Another thing ive been trying to figure out is if i can use one of my audyssey mics or my anthem mic with REW to see whats happening in my room.

Also i thought i asked this already but dont see it when i read back a bit. Would front firing subwoofer with front firing ports help?

 

[agarwalro]

Another thing ive been trying to figure out is if i can use one of my audyssey mics or my anthem mic with REW to see whats happening in my room.

unfortunately no. Those systems' softwares are designed to complement the mics. Using the mics with REW would alter measurements in unpredictable ways, thereby invalidating them.

Also i thought i asked this already but dont see it when i read back a bit. Would front firing subwoofer with front firing ports help?

Nope, changing the sub will not help because the problems stem from room dimensions, speaker/sub locations and listening position's location. Your money will be best spent on more room treatments.

 

[Hostility]

damn, i had a feeling that was going to be answer. I guess it would be really beneficial for me to invest in a mic for rew then, as it would tell me more then what arc graphs could? Also i need to grab an spl meter. Should i be looking at digital or analog? I found some on ebay as i dont think my local source store sells them.

I know your steering me away from not changing subwoofers, but in my case would dual subs help out with whats happening in my room, or still the same thing would happen?

 

[Hostility]

well ive been thinking of some ways to do bass traps. The only thing i could think of that work for me is the foam. I found someone that sells foam trap corners. So i could put one in the 1 corner that doesn't have a door in it, but what about along the wall and ceiling corners? like above the t.v and above the couch? Or i could do panels above the t.v, ect.

 

[Hostility]

Well i picked up a new pair of svs pb12-NSD's and fitted them into my front stage between my mains and CC. I only have 1 great gamma at the moment (have another on order), but from the foam from the box's are pretty good so i might make my own with that for the moment. Unfortunately i cant run ARC just yet, but right off the batt, with gain at 1/4ish, these def give me back the boom i was seeking for (again at low volumes). I also felt some nice low end a few times, so i think im going to be really pleased with these. I also couldn't localize the bass, where as before, having it beside my couch i could hear it out my right ear and tell where it was generating from. Now all i have to do is redo some of my panels the way i want them and hopefully every thing will work a bit better!

 

[Hostility]

Well i feel a little stupid, but i just found out that i had the pb12-plus (07/08) version and not the ultra. It was sold to me as the ultra and i couldn't find barley any info online about it. But after talking to somone about the differences it is the plus with 525watt bash amp.