AVS Forum banner

More SPL between 17-25hz

3K views 61 replies 14 participants last post by  sslv2pwned 
#1 ·
Guys... I am trying to make a decision regarding my subs. I currently have 4 18" Dayton HO's in 4cf sealed enclosures. I have plenty of upper end volume. However, I would like to bring up the low end. I know that if I switch to ported boxes, the problem will be solved. But, what if I stayed with sealed? How many subs do you think I would have to add?

Here is a graph showing 3 of the 4 subs and no EQ applied. Thoughts?

 

Attachments

See less See more
2
#2 ·
I would say at least another 4 if not 12. It really depends on how much more low end you are looking for. 12 would be a noticeable amount more whereas 4 more would be more a slight difference.

As you said going ported could add up to 9db in that area just by switching the box type. That would the same as adding about 8 more subs.
 
#5 ·
I thought the same thing but went with sealed also. A couple things that determined going sealed for myself was the room size and where I would be locating the subs. If you have the room I say ported. Out of curiosity what does your graph look like with all 4 subs and Audyssey running?
 
#6 ·
I don't have any old graphs. Before all four subs were up front stacked. They produced a lot more SPL then the current graphs. I currently have one sub out of order and can't stack until I get stands for my 1099's.

I will have the fourth sub back in action this weekend.

Sent from my Nexus 7 using Tapatalk
 
#10 ·
Once I get my 4th subwoofer back I will be playing with sub positions a bit more. My subs sounded the best when I had a stack of two on each side of the TV. However, I am currently down one sub and using two as stands for my 1099's. I really want near field so put the third corner loaded behind my couch. This gave me a huge 80-90hz null. I then corner loaded the third in the front right corner. This gave me a large null at 60hz. The sub is now on a back wall. While I don't have the null, I lost a lot of SPL.

One of the things causing me to flip flop between what I want to do is how the two stacks performed up front. By co-locating sub in 4 different, you automatically lose SPL. So, if I do go ported and put two full Marty's up front and two Stonehenge behind my couch, I'm wondering how 25hz - 80hz will compare to when I had the two stacks up front. I can't imagine that two full Marty's will put out the SPL of four sealed, in those frequency ranges.

With target between 17-25hz I don't see any reason to stay sealed. To me the only time I would go sealed is to
1) Hit 5-14hz with authority (personally don't care about those frequency as they do nothing for me.)
2) limited by space to 3cuft or smaller for internal size.

You wont be missing any quality going ported. I would understand if you had say um18 drivers that need huge ported cab being an issue.
I didn't realize sealed were used for the 5-14hz range. Surely only when running 12 or more subs, right?


Have you tried bringing down the peak at 38 and adding a bit of boost down lower? That seems like the easyiest thing to try first.
I have been fighting my room since I changed it around. I haven't been able to get good EQ with all the nulls I had. I just moved the third sub to its current position yesterday so my next step is to see if I can bring that peak down. I probably won't do it until I get my 4th sub back though.

Long term, I want most all my subs / bass front stage, with the addition of some near field. I want the near field for tactical feel since I am on a slab. I don't imagine the near field will add too much to the overall SPL as I am sure they won't be running at the same volume as the front. Again, I may be wrong about that.
 
#8 ·
With target between 17-25hz I don't see any reason to stay sealed. To me the only time I would go sealed is to
1) Hit 5-14hz with authority (personally don't care about those frequency as they do nothing for me.)
2) limited by space to 3cuft or smaller for internal size.

You wont be missing any quality going ported. I would understand if you had say um18 drivers that need huge ported cab being an issue.
 
#12 ·
I'm glad Richard mentioned that as that is what I was going to recommend. I'm running 8 Si's (6 in front and 2 in the back), and phase and delay makes a huuuuge difference in the FR. I can literally pull 5-6db's out of the lower end by a tiny little change to either.

I wish had the other graph to compare but I had get a nasty dip at 30 and around 15 it starts dropping like a rock with phase and delay messed up. With it dialed in, I get pure LFE bliss. :)



I would apply all of the recommendations. First experiment with phase and delay (if you have the ability), then I would pull the peak out of the 40hz region. A mini DSP with a shelf filter would help a bit with the lower end as well. Chop has one for sale in the classified section.
 
#13 ·
I'm glad Richard mentioned that as that is what I was going to recommend. I'm running 8 Si's (6 in front and 2 in the back), and phase and delay makes a huuuuge difference in the FR. I can literally pull 5-6db's out of the lower end by a tiny little change to either.

I wish had the other graph to compare but I had get a nasty dip at 30 and around 15 it starts dropping like a rock with phase and delay messed up. With it dialed in, I get pure LFE bliss. :)



I would apply all of the recommendations. First experiment with phase and delay (if you have the ability), then I would pull the peak out of the 40hz region. A mini DSP with a shelf filter would help a bit with the lower end as well. Chop has one for sale in the classified section.
Man your low end is awesome! Do you have sealed subs? How many cf are your boxes?

When you say phase, you mean setting the phase to 0 or 180, correct?
 
#15 ·
Yes. I have inuke 6000 DSPs. Fatshaft and Matt have been helping me out with some pointers on integrating them. I need to get back to it.

I didn't think a graph like yours was possible with sealed. However you do have twice the subs I do.

My replacement subwoofer came in today. I think I need to get back to basics. I am not going to worry about near field for now. I'm going to put all four subs stacked up front and get them EQ 'd the best I can. Once I see what the low end is producing, then I will make a decision whether to add more sealed or switch to ported.

Sent from my Nexus 7 using Tapatalk
 
#17 ·
I didn't think a graph like yours was possible with sealed. However you do have twice the subs I do.
Massive room gain doesn't hurt either. I'm not in a huge room (around 2k cf) and it's a sealed dedicated area. Before the 2 in the back, it didn't look that good either. That's also including a shelf filter starting at 30hz with 4db boost. My curve still has a little rise without the filter but I like my low end so......... :)
 
#21 · (Edited)
That's awesome, bass addict!


Today I was able to get my fourth sub put back together. I then moved all four subs up front putting a stack of two on each side of the television.

I was pleasantly surprised by my low end. The left side (blue line) looks pretty good. It's the right side causing me trouble. I was able to pull down 39hz, but I still have the nulls up higher. Unfortunately, I don't have much room to adjust the right stack. I know that if I move the stack to the left more, the nulls up high get smaller. The problem is the stack is already next to my right main, so I can't move enough to make a difference. I did test changing the phase 180 deg, but it had no effect. I also tested each sub individually and they tested the same as the stack, just lower SPL. I'm not sure what to do at this point.

Blue line = Left stack
Yellow line = Right stack
Purple line = Both stacks.
 

Attachments

#22 ·
Have you run the sweep with your mains? I'd be interested to see how they interact together in that 80hz range. It might smooth out a bit. Other than pulling out a bunch at 40hz, it doesn't look too bad.
 
#28 ·
could also experiment with the distance to try to push the null out of the sub region
Just because the subs are equal distance from the main listening position doesn't mean that you should set the distance and phase to zero! That is your solution right there! You could potentially make a huge difference by adjusting your phase and delay for each sub in the iNuke6000dsp software.

I must admit that I have no further advise on how to properly experiment with phase and distance adjustments as my sub amps are regular iNuke3000's, non-DSP models. (Wish that I had a way to adjust phase!) I think that wrt distance or delay settings you should perhaps just start adding delay (distance) in your receivers setup menu and take measurements as you go. It would be nice if you had the possibility of adjusting the distance/ delay for each individual sub, but most receivers can't do that , and I am not sure if that is possible with the iNukes software. I know that you can with a MiniDsp, though. Good luck! Maybe someone will post a method of how to properly set and/or experiment with the optimal phase and delay/distance settings.
I left out that my AVR has the distance for the subs set to 11.5'.

Also, how can it be a timing / phase issue when I get the null when doing a sweep of one sub on the right ?
 
#24 · (Edited)
I am very frustrated with my room. I had none of these issues before we got new furniture and had to rearrange everything. I would like to put it back but can't.

Today I spent about four or five hours moving the subs for the best response. No matter what I did I couldn't get rid of the null at 60hz.

I have two rolls of pink fluffy insulation that I stacked in various locations. I would need to get enough to stack floor to ceiling for it to help.

Question... Do you guys think adding more subs in the back will fill in the null or will it just excite the room modes more?

Edit : I did do sweeps with mains. They matched exactly except having higher SPL across the full range.


Sent from my Nexus 5 using Tapatalk
 
#25 ·
Yup, that's why the saying goes; you EQ the room, not the speakers.

Looking at that graph I still can't help but think you are having phase issues going on. The one stack doesn't exhibit near the null as the other. Yet when combined you actually lose another couple db's over the stack with the dip. Something there is not playing well together. If you have a null in that area, it shouldn't get worse when adding the other subs unless they are working against each other.

As I mentioned earlier, delay also plays a huge role in FR. After dialing in my phase; my FR was greatly improved by adjusting delays between the different subs. I'm not sure which models of mini DSP you'd have to get to be able to dial in independent delays; but for the cost, it's well worth looking into IMO.
 
#26 ·
Right now both stacks are on the same sub output. Each stack is exactly 11.5' from the MLP. Each sub is driven by a single channel of an inuke 6000 DSP. Each DSP is set to 0.0 delay since both stacks are the same distance from MLP. Phase is set to 0 degrees.

I'm pretty sure everything is setup correctly, but surely could be wrong. I think it's the room that is the problem and the way the speakers and furniture is positioned.

The right stack... The one with the null... Has a wall next to it. The left stack doesn't. The left side of the room opens to the dining room. The ceiling is 9ft on the right side and 11 or 12 ft above the left stack.

Before we got new furniture everything was setup on the wall to the right of the right sub stack. Their wasn't a wall behind MLP.

Sent from my Nexus 7 using Tapatalk
 
#32 ·
This may be a silly but have you tried to put all the subs on the left side? That plot looks pretty and unless you listen to pink noise often i'd say good enough. Music/soundtracks do not work like pink/white noise. Those nulls will not have time to develop during normal playback.
 
#34 ·
Now we are getting somewhere.

Green = Both stack no delay
Purple = 6' of delay on left stack DSP
Red = 11' of delay on right stack DSP

I'm going to work with delay on the left stack because it has a bit more SPL at the lower end.




I don't have time to do anymore now, but just as a test I threw in two quick filters on the right stack to bring down 38 and 70. Much better. I should be able to EQ both subs now without ending up with nulls. Awesome!

I just realized that this graph shows me working with the delay on the right stack.

 

Attachments

#37 ·
The answer is... It depends.

If you are only using delay to adjust the acoustic centre, then I would start by doing a global EQ (all the same) Then If you see problems coming from one side but not the other you can cut from the trouble side. As they say "small steps"

Sent from Time-Space
 
#38 ·
I have the graphs looking decent now. The subs sound much better. The bass is tight. It's not just a bunch of noise. When I play Rush, Neil Pert's kick-drums sound awesome.

I will have to get use to the upper end not having so much bass. I may drop it down to a 6-dB hard-knee slope.

Tell me what you think. I followed the Hard Knee House Curve article on the REW forum.


10-dB hard-knee slope







Blue = Both sub stacks
Pink = Both sub stacks w/ Left Main
Green = Both sub stacks w/ Right Main

 

Attachments

#43 ·
I want to thank everyone for their help. Especially bass addict, Fatshaft and mtg90. My subs have never sounded this good. I now even have ULF that I didn't have before. Even though I am on a slab, I actually have decent tactical feel. It helps that the couch is an L shaped couch that is close to the front right stack. When I play Bass I love you from YouTube, the house was breathing. Even at -30 on the AVR (wife wasn't too happy). The subs never responding like this before.

Since the last graphs posted, I redid things a couple times. First I changed to a 6dB slop in my house curve file. However, when I ran Audyssey, the subs looked and sounded terrible. So I set everything back to defaults, ran Audeyssey, ran some sweeps, added the delay back, ran some sweeps, EQ'd the subs. Since I ran Audeyssey first, I had to use a lot less cutting filters.

Now I have a decision to make. Do I add two sealed subs near field or do I switch to ported? Based on the sub 20hz I am currently getting along with how things sound / feel, I'm not sure I want to go ported.


Here is my current graph. The bottom line is subs only. The top line is three separate sweeps (subs w/ L Main, subs w/ R Main, subs w/ center).

 

Attachments

This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top