4xLAB12C subwoofers sealed with LT or ported, dual, FF, DF, ?? - AVS Forum | Home Theater Discussions And Reviews
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post #1 of 33 Old 04-07-2020, 06:29 AM - Thread Starter
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4xLAB12C subwoofers sealed with LT or ported, dual, FF, DF, ??

Hi,

I decided to buy 4 Eminence LAB12C subwoofers, there was a sale on ebay and couldn't let it go.

I will mainly use it for HT, and music. I have a stereo setup, 2 Canton CT2000 (which I would like to replace with something more 'modern' looking). I have a mini DSP and lots of power amps, QSC, to give 500-600W RMS to each sub, total of over 2000W. I have a second amp, if needed, to bump it to 4000W. Real QSC watts...

Plan is to buid 2 cabinets with 2 woofers in each cabinet.

I have been reading about room gain, I don't think I will get any. My longest wall is 11m (36 ft) and 2nd longest is 9m (30 ft). According to a rule of Bill I read, 565/ft, I will only get gain below 18 or 16Hz?

Commercially I found 2 brands using the drivers in a different way:
- BK Monolith +: ported, 95L (+ a rather short tube port)
- Zu Audio Undertone: estimated 60L sealed
- Zu Audio Submission: estimated 90L sealed

They all claim a performance below 20Hz (in room...). I would lie a max vol of 120L per driver

I have been modelling the ported dual version, the only way I can make it work is with a tuning on 22 Hz, the xmax is just reached at 30Hz. I would need 2 vents (i took square slots) of 0.08*0.4m, and 1,8 m length. The cabinet would be 60cm deep, so this is a double fold with 2 braces.

Using a tube seems more expensive than a slot and a slot adds some structure to the cabinet?

If I look at the winisd plots it all looks a bit ****, I'm not getting anywhere near 18-20Hz. Are there designs/solutions I overlooked? I think of making 2 larger cabinets (higher WAF acceptance) to avoid having subs everywhere, but should I make a combination, 1 driver down firing, 1 front firing to distribute the frequencies better? Dual opposed has an advantage for vibrations but sonically, it's just a sealed so no added extension. Would love your input so I can start building when my drivers arrive in 1 week from now
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post #2 of 33 Old 04-07-2020, 06:56 AM
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4xLAB12C subwoofers sealed with LT or ported, dual, FF, DF, ??

Here’s a tapped horn, designed for the lab12. Very solid output at 20hz on only 300w per driver.

Very large enclosure, of course.

https://www.stereo.net.au/forums/top...bwoofer-build/

I plan to build a pair as a riser, but haven’t done it yet.

EDIT: Here’s the output model with a LAB12C on 300w.



Chris

Last edited by a77cj7; 04-07-2020 at 07:05 AM.
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post #3 of 33 Old 04-07-2020, 08:09 AM - Thread Starter
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Thanks for the link, but funny enough, I actually already built 2 Alpine 12 SWR loaded horns about 5 years ago. I sold them because I got divorced, moved twice, and they were just too heavy to move around. I built it in 38mm MDF, heavily braced, bringing the weight of 1 sub well over 120KG (250 pounds). They had the advantage of being quite slim, but very very heavy, deep and not WAF friendly.

Been down that route and would like to explore the route of multiple smaller subs, vented or sealed (or something else, which fits in about 100L per driver).

Would really like to hit the 20Hz and below. I have 4 subs, so I hope by lowering the SPL on higher frequencies and boosting SPL at the lower frequency (within the limits of the driver) I can still hit it.

Last edited by belgiansound; 04-07-2020 at 08:22 AM.
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post #4 of 33 Old 04-07-2020, 08:14 AM
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Quote:
Originally Posted by belgiansound View Post
Thanks for the link, but funny enough, I actually already built 2 Alpine 12 SWR loaded horns about 5 years ago. I sold them because I got divorced, moved twice, and they were just too heavy to move around. I built it in 38mm MDF, heavily braced, bringing the weight of 1 sub well over 120KG (250 pounds). They had the advantage of being quite slim, but very very heavy, deep and not WAF friendly.

Been down that route and would like to explore the route of multiple smaller subs, vented or sealed (or something else, which fits in about 100L per driver).

Would really like to hit the 20Hz and below. I have 4 subs, so I hope by lowering the SPL on higher frequencies and boosting SPL at the lower frequency (within the limits of the driver) I can still hit it.

Fair enough. Horns aren’t for everyone, or pretty much anyone really.

20hz won’t be a problem, but how much output are you looking for?

Sealed is always the most output per occupied volume, the other alignments just add efficiency and output per driver and power.

It doesn’t sound like you’re short on power, so it just comes down to total output vs space occupied for the four drivers.

Chris
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post #5 of 33 Old 04-07-2020, 08:56 AM - Thread Starter
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Output needs to be 'adequate'. I don't listen to full levels, but I would like to 'feel' the base and lowest notes.

You got me thinking...If I want to put a horn, I could put one behind the coach. the exit of the subwoofer would be 1.5 meter of the corner. Issue is then I have 4 drivers, so only 3 left after I build one horn.

I have one 'spare' driver which might be suitable for a horn, not sure? It's an old Focal subwoofer, I put the specs in attachment. simulating a driver in ported or sealed is ok, but a horn is something else...
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post #6 of 33 Old 04-07-2020, 08:59 AM
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4xLAB12C subwoofers sealed with LT or ported, dual, FF, DF, ??

Quote:
Originally Posted by belgiansound View Post
Output needs to be 'adequate'. I don't listen to full levels, but I would like to 'feel' the base and lowest notes.

You got me thinking...If I want to put a horn, I could put one behind the coach. the exit of the subwoofer would be 1.5 meter of the corner. Issue is then I have 4 drivers, so only 3 left after I build one horn.

I have one 'spare' driver which might be suitable for a horn, not sure? It's an old Focal subwoofer, I put the specs in attachment. simulating a driver in ported or sealed is ok, but a horn is something else...

Can’t model it in the horn without inductance spec.
EDIT: nevermind, didn’t see it.


Have you integrated various alignments before? Getting a horn to play well with sealed will take some work.

Chris
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post #7 of 33 Old 04-07-2020, 09:09 AM
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4xLAB12C subwoofers sealed with LT or ported, dual, FF, DF, ??

Modeled the focal in the Lab12 horn. I wouldn’t recommend it.
100w input power, hitting nearly 11mm of excursion. I’m not sure how conservative focal is on their excursion rating, so this is already pushing it.



Chris
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post #8 of 33 Old 04-07-2020, 09:13 AM
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You could do the horn behind the couch, and two 20hz ported, single driver enclosures. Or three, if you prefer.

I haven’t yet built a TH, so am not familiar with their specific integration. I would expect integration with similar-tune ported to be very doable though.

Chris
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post #9 of 33 Old 04-07-2020, 04:28 PM
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Quote:
Originally Posted by belgiansound View Post
but should I make a combination, 1 driver down firing, 1 front firing to distribute the frequencies better?
That won't make the slightest bit of difference at the wavelengths involved in a sub, the drivers are radiating omnidirectionally anyway.


Quote:
Originally Posted by belgiansound View Post
Dual opposed has an advantage for vibrations but sonically, it's just a sealed so no added extension
There is no reason you can't do dual opposed ported. My PA subs were PP ported since the late 80s.


With the Cantons you could also make the PP sealed which would make them much smaller at around 40L/driver net; cross them at 80-100Hz actively with a LPF/HPF. This is what I will be doing with the new bedroom speakers after I move in a few months, as part of a 4 way (2x12 LABs, 1x12, 1x6, 1x HF), active and EQd. Note mine are the original series and ran in my LABhorns in my living room for several years.



Round vs slot ports: I much prefer round as they have a lower surface area to CSA ratio and will chuff later than a slot. They are also not expensive as there are multiple useful sizes at any hardware store used for plumbing. They're also easier to flare, and easier to tune in the final design. Yes a slot will add some bracing, but if you design it with good bracing in the first place it will be moot.


Lastly, don't ever believe anything Zu say. Their designs are generally junk.

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Not to derail this thread, but if I’m reading it correctly the Zu Audio sub Linked is a lab 12 driver (200£) in a sealed box with a hypex plate amp and they’re charging almost 6 grand?? Whattt


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Quote:
Originally Posted by monty6400 View Post
Not to derail this thread, but if I’m reading it correctly the Zu Audio sub Linked is a lab 12 driver (200£) in a sealed box with a hypex plate amp and they’re charging almost 6 grand?? Whattt
All down to the power of marketing and how easily deluded many 'philes are. The Druids use two cheap Eminence drivers badly aligned in a shiny box and they sold a lot. And they sounded awful.

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post #12 of 33 Old 04-07-2020, 08:17 PM
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LAB 12 works in the BFM THT. Not a small sub but not super big either. A little tricky to build. Four of those would be more than you need.

Otherwise, just build four 4 cubic foot ported boxes.
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post #13 of 33 Old 04-08-2020, 07:21 AM - Thread Starter
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Thanks for the simulation! This makes the horn solution not a winner, better to buy an other driver in that case.

Quote:
Originally Posted by A9X-308 View Post
That won't make the slightest bit of difference at the wavelengths involved in a sub, the drivers are radiating omnidirectionally anyway.


There is no reason you can't do dual opposed ported. My PA subs were PP ported since the late 80s.


With the Cantons you could also make the PP sealed which would make them much smaller at around 40L/driver net; cross them at 80-100Hz actively with a LPF/HPF. This is what I will be doing with the new bedroom speakers after I move in a few months, as part of a 4 way (2x12 LABs, 1x12, 1x6, 1x HF), active and EQd. Note mine are the original series and ran in my LABhorns in my living room for several years.



Round vs slot ports: I much prefer round as they have a lower surface area to CSA ratio and will chuff later than a slot. They are also not expensive as there are multiple useful sizes at any hardware store used for plumbing. They're also easier to flare, and easier to tune in the final design. Yes a slot will add some bracing, but if you design it with good bracing in the first place it will be moot.


Lastly, don't ever believe anything Zu say. Their designs are generally junk.
Thanks! so in summary:
either ported, can be dual opposed, best with round ports.

The thing is, I have been modelling the dual ported option in WINISD, box of 250L tuned to 22Hz, I would need to put 6 ports of 1,1m length and 0,1 m diameter. Thats about 9*6=54L cabinet space!
So all together the box would be 300L internal volume...this would make it about as large as a folded horn.

I just wonder how the BK monolith can get by with only ONE port???

Other option is sealed, this would make the volume a lot lower but the F3 would be substantially higher as well?

Not sure if the sealed option will give me enough 'LFE' experience...

I'm still not clear about the volume for the sealed option as well. If you apply enough power, 40L will dig as deep as 100L sealed or not?

Could be an option to save some more for an extra 18" sub which I can put sealed somewhere in my room to dig extra deep when I have some LFE rich movies instead of building extremely large ported options....

Last edited by belgiansound; 04-08-2020 at 07:27 AM.
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post #14 of 33 Old 04-08-2020, 01:13 PM
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Quote:
Originally Posted by belgiansound View Post
The thing is, I have been modelling the dual ported option in WINISD, box of 250L tuned to 22Hz, I would need to put 6 ports of 1,1m length and 0,1 m diameter. Thats about 9*6=54L cabinet space!
So all together the box would be 300L internal volume...this would make it about as large as a folded horn.
I don't have my sim software on this laptop to confirm, but that is an extreme amount of port volume. I don't recall when sim'd ported LAB12 it being anywhere near that much. Please post your winISD sims including port air speed to have it checked out.

Quote:
Originally Posted by belgiansound View Post
I just wonder how the BK monolith can get by with only ONE port???
Because most measurements are done at 1W so the FR will look good, but the port will begin to compress and/or chuff as the driver moves towards Xmax. With a few, generally ID companies as exceptions, commercial subs suck. Big time.

Quote:
Originally Posted by belgiansound View Post
Other option is sealed, this would make the volume a lot lower but the F3 would be substantially higher as well?

Not sure if the sealed option will give me enough 'LFE' experience...
Yes F3 will be higher, about 40Hz for a LAB12 in a Qt=0.707 box.
Based on AVS standards, no, it will not give you much of an LFE experience.


Quote:
Originally Posted by belgiansound View Post
I'm still not clear about the volume for the sealed option as well. If you apply enough power, 40L will dig as deep as 100L sealed or not?
You will get to Xmax with less power in a larger box as there is more air in there and the air spring will be more compliant meaning less resistance for the motor to overcome. Roll off will be more gradual, but F3 will be a bit higher.

Quote:
Originally Posted by belgiansound View Post
Could be an option to save some more for an extra 18" sub which I can put sealed somewhere in my room to dig extra deep when I have some LFE rich movies instead of building extremely large ported options....
An 18 sealed will likely offer no improvement over the LABs sealed in terms of F3. A UM18 gives about the same 40Hz F3 IIRC.

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post #15 of 33 Old 04-10-2020, 01:27 AM - Thread Starter
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ok, so if I want to get LFE, I need to continue down the vented option road.

In attachment the simulations made with the LAB12C vented dual. I added a high pass and low pass filter to protect the driver excursion. If I add only 4 vents the air speed at 20Hz is still very high. Adding 6 would result in 1.4m each, and a air speed at 20Hz below 17. I think however I might need to learn to live with a small amount of chuffing at that frequency as it's not very often hit during use? Maybe over focussing on something less relevant?
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post #16 of 33 Old 04-10-2020, 04:37 AM
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4xLAB12C subwoofers sealed with LT or ported, dual, FF, DF, ??

Quote:
Originally Posted by belgiansound View Post
ok, so if I want to get LFE, I need to continue down the vented option road.

In attachment the simulations made with the LAB12C vented dual. I added a high pass and low pass filter to protect the driver excursion. If I add only 4 vents the air speed at 20Hz is still very high. Adding 6 would result in 1.4m each, and a air speed at 20Hz below 17. I think however I might need to learn to live with a small amount of chuffing at that frequency as it's not very often hit during use? Maybe over focussing on something less relevant?

Use a high pass filter to control cone excursion below tune. That will significantly reduce your port velocity. Start with a 2nd order Butterworth at 20hz. Adjust slope and frequency as needed.

If you click on the unit next to port length, you can change it to in or cm. Unless you like thinking in meters. Same with volume and port diameter.

Chris

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post #17 of 33 Old 04-10-2020, 05:41 AM
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Ok, I looked closer and see you do have a hpf. I’m assuming something is off in your driver data. I ran a quick model for you.

I dropped the input power to 800w (400 per driver) to control excursion.
2 4” round ports. Velocity is a bit high, but you’ll have trouble stuffing longer ports in the box. A slot is much easier to fit, but has the disadvantages listed earlier.







Chris
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post #18 of 33 Old 04-12-2020, 12:10 PM - Thread Starter
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Thanks! Sorry for the late reply but I gave myself a crash course winisd. I actually prefer the 'pro' version, easier to compare multiple drivers.

I compared multiple options, I always came to the 200L to 20Hz tuning...but I found 4 vents of 10,2CM (4") to work better. Keeps the air speed low and it's 'only' about 35L extra in an already big box.

I also put some time putting some filters. As I have 2 drivers in the box I had enough SPL to reduce in the higher frequency and use this excursion for a boost in the lower frequencies. I guess it's basically some kind of linkwitz transform...but I'm not self educated enough to fully understand the LT...

I hope these filters are correct and will actually work?

I also think, with 2 of these dual subs, I will not quickly put it to 1000W per box, so the excursion and air velocity should be OK.

The drivers arrived friday, only need to order the ports! I was wondering, I need quite a lot of tubing (about 10 meters). I read that 'PE' tubes are better than 'PVC'. The PE tubes are about 13 EUR/M, so would be about 130 EUR. Only wonder about the flares...Are there flares you can glue to PE tubes you can buy in a hardware shop?

I found some kits online, but the were always with a shorter tube.

I put some screenshots in attachments.
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post #19 of 33 Old 04-12-2020, 12:57 PM
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4xLAB12C subwoofers sealed with LT or ported, dual, FF, DF, ??

Quote:
Originally Posted by belgiansound View Post
Thanks! Sorry for the late reply but I gave myself a crash course winisd. I actually prefer the 'pro' version, easier to compare multiple drivers.

I compared multiple options, I always came to the 200L to 20Hz tuning...but I found 4 vents of 10,2CM (4") to work better. Keeps the air speed low and it's 'only' about 35L extra in an already big box.

I also put some time putting some filters. As I have 2 drivers in the box I had enough SPL to reduce in the higher frequency and use this excursion for a boost in the lower frequencies. I guess it's basically some kind of linkwitz transform...but I'm not self educated enough to fully understand the LT...

I hope these filters are correct and will actually work?

I also think, with 2 of these dual subs, I will not quickly put it to 1000W per box, so the excursion and air velocity should be OK.

The drivers arrived friday, only need to order the ports! I was wondering, I need quite a lot of tubing (about 10 meters). I read that 'PE' tubes are better than 'PVC'. The PE tubes are about 13 EUR/M, so would be about 130 EUR. Only wonder about the flares...Are there flares you can glue to PE tubes you can buy in a hardware shop?

I found some kits online, but the were always with a shorter tube.

I put some screenshots in attachments.

The problem with 4 ports is your vent length. Your longest vent is showing just under 5ft long. Where are you going to fit four of those in this small enclosure?

The PE precision ports are great for chuffing. The kits are only 17” long uncut though IIRC. Extensions are available, but not cheap. They may or may not work with hardware store elbows to bend them. Bends aren’t great anyway, but often necessary.

You can make your own flared ports from hardware store tubing, tutorials are available if you search on google.

I generally switch to slot ports in cases where I need more than 17” precision ports.


EDIT: You are also showing excessive excursion, especially on the two higher tunes. Raise your hpf to reduce excursion below tune in those.
That driver is only rated for 13mm xmax. Eminence drivers are generally rated conservatively. I don’t see a listed coil length to make a prediction of how far you can push it though.
EDIT2: Assuming eminence is using the 1/3gap xmax rating as they do on other woofers, the coil height calculates as 30.33mm. Taking it to 2/3 gap, what I use for enclosure design, is 17.3mm. I would adjust your model to stay under 17mm.

Chris

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post #20 of 33 Old 04-13-2020, 06:14 AM - Thread Starter
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Hi Chris,

Thanks for the feedback! I played some more with the filters and it looks safe now until 900W, at 1000W it's 1mm above xmax. The xmech should be 22mm according to the Eminence site, so I should be safe. If I build the box correctly off course and don't need to EQ much more than I already did...find it difficult doing the EQ on a theoretical model. In the real life, I will not have this flat response I'm afraid. The SPL is pretty flat until 20Hz, the highpass is put in higher, and for the air velocity I used the 4 big ports, this keeps the air flow really low.

I made a drawing of the layout I would use. I calculated with an internal volume of 258L. 20L for bracing and drivers, 38L for the ports. Height of the box (external) would be 1,2m, 0,6m deep and 0,45 m wide.

Bottom line the tubes would be about half way into the box, about 10cm from the back of the drivers and about 25cm from the 'cone'. I hope this is ok?

I also simulated the option with 4 tubes of only 8,2cm. This would have an air speed in between both options and a shorther length, requiring only 1 bent and the opening near the back panel, further away from the driver.

Personally I prefer as little chuffing as possible, the box size allows it, but I'm not sure about the proximity to the driver.

Thanks a lot!
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post #21 of 33 Old 04-13-2020, 06:29 AM
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4xLAB12C subwoofers sealed with LT or ported, dual, FF, DF, ??

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Originally Posted by belgiansound View Post
Hi Chris,

Thanks for the feedback! I played some more with the filters and it looks safe now until 900W, at 1000W it's 1mm above xmax. The xmech should be 22mm according to the Eminence site, so I should be safe. If I build the box correctly off course and don't need to EQ much more than I already did...find it difficult doing the EQ on a theoretical model. In the real life, I will not have this flat response I'm afraid. The SPL is pretty flat until 20Hz, the highpass is put in higher, and for the air velocity I used the 4 big ports, this keeps the air flow really low.

I made a drawing of the layout I would use. I calculated with an internal volume of 258L. 20L for bracing and drivers, 38L for the ports. Height of the box (external) would be 1,2m, 0,6m deep and 0,45 m wide.

Bottom line the tubes would be about half way into the box, about 10cm from the back of the drivers and about 25cm from the 'cone'. I hope this is ok?

I also simulated the option with 4 tubes of only 8,2cm. This would have an air speed in between both options and a shorther length, requiring only 1 bent and the opening near the back panel, further away from the driver.

Personally I prefer as little chuffing as possible, the box size allows it, but I'm not sure about the proximity to the driver.

Thanks a lot!

Looks pretty good. Again, I would be unafraid to push those drivers to 17mm, and you’re well under that. The performance may go non-linear above xmax, so excursion could be slightly less than modeled.

As for the ports, you’ll be ok. You want to keep the end of the port a minimum of port-width from any obstruction. You’re right there. Looks like proximity to the outer wall also. Both of these will just potentially lower tune ever-so-slightly though.

For the amount of tube you need, its probably worth it to make your own flares.
You can buy just the flares as well.

EDIT: Looks like you can get rid of half the 90* bends.
Move the ports outside the drivers on both sides.
Run the first set like you currently have, but instead of bending back toward the front, continue along back wall till desired length.
Run the second set mirrored, but with the bend closer to the front of the cabinet so they run between the drivers and the first ports.

EDIT2: As for the eq, try adjusting the Q factor to change the width. You can likely get a pretty good response with a single wider boost instead of the 3 narrow ones.

To accurately simulate with the eq on, halve your power for every 3db boost. It looks like you’re boosted about 3db total at the highest, so change your input power to 500w. That should drop your excursion and velocity back where they were.

Chris

Last edited by a77cj7; 04-13-2020 at 06:39 AM.
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post #22 of 33 Old 04-13-2020, 09:59 AM - Thread Starter
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ok, thanks regarding the bends, I made a sketch in attachment. Is this what you mean? I had been thinking about this as well, but not sure if there will be turbulence caused by the tube in front of the opening of the other tube?

I also calculated the slotted option, would need an opening of 9cm. Including the wood for making the slot, this would be about (9+9+1,8+1,8) * .36 * .54 = 42L, which is more than the tubes.

All those options...
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post #23 of 33 Old 04-13-2020, 12:51 PM
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4xLAB12C subwoofers sealed with LT or ported, dual, FF, DF, ??

Quote:
Originally Posted by belgiansound View Post
ok, thanks regarding the bends, I made a sketch in attachment. Is this what you mean? I had been thinking about this as well, but not sure if there will be turbulence caused by the tube in front of the opening of the other tube?

I also calculated the slotted option, would need an opening of 9cm. Including the wood for making the slot, this would be about (9+9+1,8+1,8) * .36 * .54 = 42L, which is more than the tubes.

All those options...

Yup, thats it. Any turbulence caused by the proximity to the wall/other port will be many times less than caused by the additional 90*.

Slots always take up more cabinet volume due to the material thickness. They add effective cabinet bracing to the wall their attached to though.

Speaking of which, hopefully you are planning to brace the cabinet? That will take some volume as well.

Chris

Last edited by a77cj7; 04-13-2020 at 12:55 PM.
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post #24 of 33 Old 04-13-2020, 01:27 PM - Thread Starter
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Hi, indeed, I accounted for the bracing as well (20L per cabinet).

In that case, this solution should be the best if I go for the ported tube version! Slot ported is off for me, there must be a reason most high end subs use tubes as well.

One other option though...I skipped the passive radiator option because the dayton 15" passive is 155 euro, which would double the total cost (I need 4 of them).

I noticed however the 18" radiator is pretty cheap and the specs look a lot more impressive compared to the 15". Price is also not much more than a 15", it's only 180 EUR. According to my calculation, the Vd of 1 18" radiator is 6 times more than 1 LAB12C. I understood it needs to be double, so as I have 2 woofers it needs to be 4x....which it is.

https://www.soundimports.eu/nl/dayto...rss460-pr.html

Box size would be smaller, about 120L I estimate, and I will make some savings on the material. I would estimate about 150 EUR needing less wood, PE tubes and flares?

But I wonder if the output will be less compared to a classic vented box? You loose some energy moving that 18" passive so total output I imagine will be lower.
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post #25 of 33 Old 04-13-2020, 02:27 PM
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4xLAB12C subwoofers sealed with LT or ported, dual, FF, DF, ??

Quote:
Originally Posted by belgiansound View Post
Hi, indeed, I accounted for the bracing as well (20L per cabinet).

In that case, this solution should be the best if I go for the ported tube version! Slot ported is off for me, there must be a reason most high end subs use tubes as well.

One other option though...I skipped the passive radiator option because the dayton 15" passive is 155 euro, which would double the total cost (I need 4 of them).

I noticed however the 18" radiator is pretty cheap and the specs look a lot more impressive compared to the 15". Price is also not much more than a 15", it's only 180 EUR. According to my calculation, the Vd of 1 18" radiator is 6 times more than 1 LAB12C. I understood it needs to be double, so as I have 2 woofers it needs to be 4x....which it is.

https://www.soundimports.eu/nl/dayto...rss460-pr.html

Box size would be smaller, about 120L I estimate, and I will make some savings on the material. I would estimate about 150 EUR needing less wood, PE tubes and flares?

But I wonder if the output will be less compared to a classic vented box? You loose some energy moving that 18" passive so total output I imagine will be lower.

I’m not a good one to comment on passives, I’ve never modeled/tuned/used them.

I guess my mains have them, lol.
@Chris Popovich has been working with some lately, maybe he can weigh in.

Chris
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post #26 of 33 Old 04-13-2020, 04:38 PM
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I like PR cabinets, but the quality of the PR does make a difference. The 18" PR you are referencing looks totally worth trying out.

Passive radiator alignments are higher order than ported, but the losses are pretty much a wash in my experience. Remember that 18" driver doesn't have to excurt very far to move significant air, you get no port noises, and you don't lose the port volume from your box. Give it a go!
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post #27 of 33 Old 04-14-2020, 04:11 AM - Thread Starter
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Thanks Chris!

i tried to model it in winisd. A lot of changing the box volume, PR weight and filters, the best I could do is in attachment. The SPL is 1db lower compared to the vented, the max SPL is a big difference (but that is due to the higher excursion I guess).

Excursion is a bit higher compared to the vented option because I needed to EQ more.

Hope I did everything ok, it seemed like I hit a 'sweet spot' with the enclosure size, it's 70L smaller (!) if you include the vents, this is a difference of 108L, almost half!

I will seriously consider it. I would do a 0.5 wide, 0.5 deep and 0.7m heigh enclosure, with the passive on the front and the lab12 dual opposed, bottom and top firing or firing from both sides. Not sure if firing from both sides is good, as placement will be a bit more difficult. Will look cool up front though with the big passive radiator.

Not sure if you can give any tips for modelling the driver?
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post #28 of 33 Old 04-15-2020, 04:40 AM - Thread Starter
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ok, discussed with the GF and decided to order the 18" passives. (It helped that I sold some photo gear yesterday for 650 euro). They will be here before end of this week!

Will need to see about the wood, I will need to order it precut if I want it delivered due to the corona crisis, going to the hardware shop is no longer possible here in Belgium

I'm glad I took this decision, now I need to decide on the orientation of the 2 LAB12C drivers.

- Dual opposed: down and top firing. Downside: size. I will need to keep it 3" from the floor and add a top plate 3" from the driver, this will add in total about 7" to the total height. Upside: 'controllable' as the sound will bounce off of a 'calculated' bottom or top plate. Easier to place?
- Dual opposed: side firing. Downside: not sure about the 'in room response' as the sound will bounce on the tv, curtains, the other tower speakers, ... but not directly to my seating position. Upside: size and ease of construction
- non-opposed: down and side firing woofer. Downside: not dual opposed, so more 'vibrations' in the enclosure. Still 1 driver to the side, placement? also slightly higher (3") compared to the side firing dual opposed. Upside: some 'tactile' feel by the down firing sub and only 1 side woofer to worry about

Would love if some of you can share your experience on these options, so I can start drawing the enclosure and order some wood
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post #29 of 33 Old 04-15-2020, 06:01 AM
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Quote:
Originally Posted by belgiansound View Post
ok, discussed with the GF and decided to order the 18" passives. (It helped that I sold some photo gear yesterday for 650 euro). They will be here before end of this week!

Will need to see about the wood, I will need to order it precut if I want it delivered due to the corona crisis, going to the hardware shop is no longer possible here in Belgium

I'm glad I took this decision, now I need to decide on the orientation of the 2 LAB12C drivers.

- Dual opposed: down and top firing. Downside: size. I will need to keep it 3" from the floor and add a top plate 3" from the driver, this will add in total about 7" to the total height. Upside: 'controllable' as the sound will bounce off of a 'calculated' bottom or top plate. Easier to place?
- Dual opposed: side firing. Downside: not sure about the 'in room response' as the sound will bounce on the tv, curtains, the other tower speakers, ... but not directly to my seating position. Upside: size and ease of construction
- non-opposed: down and side firing woofer. Downside: not dual opposed, so more 'vibrations' in the enclosure. Still 1 driver to the side, placement? also slightly higher (3") compared to the side firing dual opposed. Upside: some 'tactile' feel by the down firing sub and only 1 side woofer to worry about

Would love if some of you can share your experience on these options, so I can start drawing the enclosure and order some wood

Sound is not going to significantly change based on cone orientation at subwoofer frequencies.

Room interaction does some strange things, but unless you have a current sub you can try out, its hard to predict.

I like the DO side-firing aesthetics.
I don’t believe you want the PR top or bottom due to sag issues, especially with added mass to tune.

Chris
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post #30 of 33 Old 04-15-2020, 06:36 AM - Thread Starter
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Quote:
Originally Posted by a77cj7 View Post
Sound is not going to significantly change based on cone orientation at subwoofer frequencies.

Room interaction does some strange things, but unless you have a current sub you can try out, its hard to predict.

I like the DO side-firing aesthetics.
I don’t believe you want the PR top or bottom due to sag issues, especially with added mass to tune.

Chris
Hi Chris,

Thanks!

I was thinking of making the front baffle fully symmetrical, so I can still decide while placing the subs, but would make the enclosure deeper again...

anybody experience with side firing subs?
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