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Discussion Starter · #1 ·
Ok, so after poking my nose around the forums a lot about 6 months back, I started trying to teach myself to model drivers in WINISD and build a pair of subs. Long story short, a lot of the general advice that came my way, was "build the biggest sub you can accommodate for the space you have!" My Room is 3m x 4m (2.4 high) with the sofa on one 4m wall and my front soundstage and subs on the other 4m wall.

In the end I picked the Lavoce SAF184.03 driver and I decided my maximum sub dimensions were 775w x 520h x 500d (I actually regret this a little, they are still huge for my room!). Total internal volume was around 128ltr net. Subs were tuned to 21hz (another mistake I should have gone lower but no biggy) & i purchased a NX6000D to power them both

Here is my native response with no corrections at all, audyssey or dsp - crossovers set at 200
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and this is probably my best EQ effort using the behringer DSP. My 2 biggest issues have been the big peaks around 52hz and 80hz. The 80hz one being the biggest problem as no amount of EQ seems to affect it too greatly.

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Now dont get me wrong - to my ears the Subs sound good and theyve impressed plenty of people with the room shake and chest punch. But im applying massive EQ - at the limits of the behringer (-15) and using all 8 filters, which I know isnt a great thing and I like to know im getting the best from what I have. Even after -15 corrections audyssey still wants to reduce my sound.

Im sure my room is likely a huge part of the problem and unfortunately there is little i can do about this. I have already moved the sub around 8 various positions to get the best combination of the least peaks and in the best position I will get. I heard my old 12" ported sub (Branded) in another room the other day though and couldnt help but think im missing a bit of quality.

In reality - I dont think I needed as much power as I have, So im getting tempted to give Sealed a go, as an inexpensive solution or simply for a bit of fun to hear the difference. They would also be more wife friendly

So the point of the post.

1) What do you make of what I did in the first place and the results shown
2) If I did go sealed with these drivers for fun, do you have any recommendation on design (other than use different drivers, I want to keep with these!)

I have been reading about the Qtc value and 0.707 being optimal but ive then read conflicting information about how this can vary and it has once again gone over my head. I would like to keep the sub at 520H x 610W - varying the depth to achieve the desired volume. WINISD shows around 66ltrs to be the desired volume for 0.707 qtc

Thanks for any input! :)
 

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I could be wrong, but I doubt going sealed will have much, if any, affect on those peaks. You mentioned audyssey, does your avr have XT32? That should get your initial response pretty flat.
 

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Venu360, Niles power Amp, Emotiva power Amps, Crown power Amps, Yamaha CX-A5100, DIY speakers, UHZ65
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Room modes especially at the 80 Hz.
Move measurement microphone. Typical floor bounce.
Audioholics website has some clues to help. Going sealed is not going to solve room modes.
 

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Discussion Starter · #4 ·
I could be wrong, but I doubt going sealed will have much, if any, affect on those peaks. You mentioned audyssey, does your avr have XT32? That should get your initial response pretty flat.
Yep, i missed that one off. I use a Marantz SR7011 in 5.2.4 configuration. Audyssey just doesnt seem to get it flat which is why im looking for the change. I think Audyssey tries to correct too much, im giving it too much work to do which is why maybe it isnt as successful as it could be?

Here is the only sweep I have of my old 12" ported sub. I was in a single sub configuration then

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This is just with audyssey - no dsp involvement at all (as i didnt have the amp or know how to use it)

Room modes especially at the 80 Hz.
Move measurement microphone. Typical floor bounce.
Audioholics website has some clues to help. Going sealed is not going to solve room modes.
I havent got a proper microphone stand but did place my UMIK-1 into the rudimentary cardboard stand that you use to do the audyssey room sweeps. This does get the mic around 2ft away from the surrounding sufaces

Also when doing audyssey sweeps I only use 6 position as the final 2 positions would be far too close to the rear wall
 

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um... forgive me if i missed it... but do you have both subs on the same wall with the front soundstage? in a rectangular room (vs. an irregularly shaped room), you should have subs positioned opposite each other to provide the most even bass response in room...

those are definitely room modes, and placement and alignment/phase can help with that. There are some guides on how to get a good integration out there... I like Rob's from AVRant...
 

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Discussion Starter · #6 ·
um... forgive me if i missed it... but do you have both subs on the same wall with the front soundstage? in a rectangular room (vs. an irregularly shaped room), you should have subs positioned opposite each other to provide the most even bass response in room...

those are definitely room modes, and placement and alignment/phase can help with that. There are some guides on how to get a good integration out there... I like Rob's from AVRant...
Yes youre correct, subs are either side of the centre channel but between the FL and FR. As its a small room the other corners are full or very close to furniture. The Back right corner for example could take a sub but it would be be in the corner of the room and the end of a sofa. I have tried the sub in this position already and got little benefit. I got good results for the MLP by keeping 1 sub between the C and FL and the other sub right in the corner passed the FR, but the results werent as good across all 3 listening positions. I have also experimented with delay and inverting the phase but as 1 sub is so powerful on its own anyway I was getting little reduction in the problem areas. This was part of the reason why i thought about the Sealed sub as an option.
 

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I'm still baffled as to why XT32 isn't flattening out your peaks.
 

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Discussion Starter · #8 ·
I'm still baffled as to why XT32 isn't flattening out your peaks.
I only started doing sweeps after I got the DIY bug so I've not much experience of what to expect, but I can only assume that more problems are created when audyseey corrects existing issues, that's why i wanted fewer peaks and nulls before hand. Maybe get closer to what I need before running audyseey
 

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I only started doing sweeps after I got the DIY bug so I've not much experience of what to expect, but I can only assume that more problems are created when audyseey corrects existing issues, that's why i wanted fewer peaks and nulls before hand. Maybe get closer to what I need before running audyseey
Yeah this is the correct way of doing it. Get the best response you can and then run Audyssey. Sorry, I'm not clear on if that's what you did or not.

Are you running dual 18s? Are you applying DSP to each individually or together? Does your receiver calibrate each sub individually or together?

I will say that I don't think you'd be better off with sealed unless you're having some massive crazy phase issues. You'll probably just lose more volume around 20hz and need more eq.
 

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Discussion Starter · #10 ·
Yeah this is the correct way of doing it. Get the best response you can and then run Audyssey. Sorry, I'm not clear on if that's what you did or not.

Are you running dual 18s? Are you applying DSP to each individually or together? Does your receiver calibrate each sub individually or together?

I will say that I don't think you'd be better off with sealed unless you're having some massive crazy phase issues. You'll probably just lose more volume around 20hz and need more eq.
Yes running Dual 18's - Lavoce SA184.03 in 128ltr enclosures

Ok so my process was.

1) Site a single subwoofer around the room (in my limited possible locations) to find the best placements areas with least peaks and nulls
2) Add in the second subwoofer and adjust the delay to get a positive increment - also experiment with inverting phase
3) Then EQ both subs together using behringer DSP
4) Run Audyssey on Marantz SR7011 (XT32)


I didnt know if the tighter base generally associated with sealed subs would result in smaller peaks. I just want to try and minimise the amount of EQ im having to do. Also bare in mind The marantz AVR has the subs set at about -8ish i think at the moment, even after I have some of the DSP at -15 in places, so im not lacking in SPL. The amount of EQ im having to do cannot be producing the best possible outcome. But my inexperienced ears cant say...

I agree my main concern is the lower frequencies if I switch to sealed although sealed would also be more wife friendly in size. I know the avs mantra of bigger is better here (which is how i ended up with these in the first place) but I am curious to see how sealed subs would sound as ive never had one.

Also in terms of siting - I know opposite corners are often recommended but I thought either side of the centre channel was usually a good spot too? Either side of the centre channel has given me my best response across the 3 listening positions.
 

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Discussion Starter · #11 ·
Couple of pics to help - The speakers are XTZ M6's - I did a front gloss panel on the subs to match which I would transfer to another box if i made one. The furniture to the sides of the subs have since moved and are a little more spaced out. But again, you can see why I might be considering smaller sized sealed subs
 

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Yes running Dual 18's - Lavoce SA184.03 in 128ltr enclosures
...
I'm not an expert on dual sub setup, so I won't speak to that, but what you did sounds generally right to me. In fact I gave up on trying to place my subs and have been running them together stacked in one corner, but I have a small room and only a couple seats so it works.

But I don't think you should be too worried about having to apply a lot of EQ. As long as you aren't at the limits of your amp's power and your drivers' xmax, I think adding EQ within reason is fine and that the benefits of a flat response vastly outweigh any downsides. Towards that end, I might choose sub locations based on volume output at the MLP rather than response flatness. The more spl you have to work with, the less work the drivers will end up having to do.

I can't imagine any reason sealed boxes in the same locations wouldn't have those same peaks, but if it's a size thing and you know you have plenty of headroom to make up for the loss in output down low doing to sealed, go for it. If I were you, either way I'd grab a minidsp. That would give you plenty of filters and the ability to calibrate each sub separately. It's also the next logical step after buying a measurement mic :D

EDIT: beautiful construction on the subs, by the way.
 

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If you run the subs on separate amp channels, you can EQ individually. Remove all filters, and re-run your sweep using one sub. REW will give you proper DSP settings. After EQing the first sub, use the same process with the second sub. Then repeat the process for both subs together.
 

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I didnt know if the tighter base generally associated with sealed subs would result in smaller peaks.
Huh?
 

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Discussion Starter · #16 ·
If you run the subs on separate amp channels, you can EQ individually. Remove all filters, and re-run your sweep using one sub. REW will give you proper DSP settings. After EQing the first sub, use the same process with the second sub. Then repeat the process for both subs together.
Dont know about you but REW's EQ do a terrible job for me - I always end up just having to manually guess, sweep, correct - re sweep and keep going. The frustrating thing is when I get somewhere near I check the other positions and there is a 5+db gap between positions, which when you have every speaker set out perfectly symmetrically is just frustrating
 

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Yes youre correct, subs are either side of the centre channel but between the FL and FR. As its a small room the other corners are full or very close to furniture. The Back right corner for example could take a sub but it would be be in the corner of the room and the end of a sofa. I have tried the sub in this position already and got little benefit. I got good results for the MLP by keeping 1 sub between the C and FL and the other sub right in the corner passed the FR, but the results werent as good across all 3 listening positions. I have also experimented with delay and inverting the phase but as 1 sub is so powerful on its own anyway I was getting little reduction in the problem areas. This was part of the reason why i thought about the Sealed sub as an option.

it's not about power, but if you aren't seeing improvements after playing with positioning, delay, etc, then you haven't optimized integration... though if your room isn't rectangular/sealed, then it's still an integration issue, but is more complicated to optimize... either way, running multiple subs, requires them to be spread apart. not discounting any integration work you have already done, but you might want to try this approach for 2 subs... (you should start at step 5)
 

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Couple of pics to help - The speakers are XTZ M6's - I did a front gloss panel on the subs to match which I would transfer to another box if i made one. The furniture to the sides of the subs have since moved and are a little more spaced out. But again, you can see why I might be considering smaller sized sealed subs
Those subs are so close together that for most sub frequencies they are essentially co-located... 80 Hz is about 14 ft wavelength... you need to get at least 1/4 wavelength apart to start getting effective multi-sub advantages by evening response (rule of thumb, but not always true...)

Looks like your placement is at the edge of that at 80 Hz. and probably not much below...
 

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Dont know about you but REW's EQ do a terrible job for me - I always end up just having to manually guess, sweep, correct - re sweep and keep going. The frustrating thing is when I get somewhere near I check the other positions and there is a 5+db gap between positions, which when you have every speaker set out perfectly symmetrically is just frustrating
yeah, not the right process for multiple subs with more than one seating location... see my post with the setup guide... it works surprisingly well without going all in on the MSO route....
 

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Discussion Starter · #20 ·
it's not about power, but if you aren't seeing improvements after playing with positioning, delay, etc, then you haven't optimized integration... though if your room isn't rectangular/sealed, then it's still an integration issue, but is more complicated to optimize... either way, running multiple subs, requires them to be spread apart. not discounting any integration work you have already done, but you might want to try this approach for 2 subs... (you should start at step 5)
Thanks will give this a go, maybe theres some extra detail ive overlooked. I did actually try some of this today, placing one sub in the rear right corner (but its right next to the sofa) and the other sub almost in the front left corner, but again I couldnt balance the response across all 3 listening positions. At the moment im settling with on sub in the front right and the other sub left of centre as was in the picture. Cone to Cone they are approximately 3 meters apart and both facing towards the sofa wall

Also to confirm the room is rectangular and sealed - 4m x 3m
 
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