Nearfield bass cabinet with multiple woofers for HT - Page 2 - AVS Forum | Home Theater Discussions And Reviews
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post #31 of 106 Old 02-05-2017, 12:35 PM - Thread Starter
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Quote:
Originally Posted by markus767 View Post
Very bad idea as this will most likely change the behavior in unforeseeable ways. If you want to have the full benefits of a real near field setup you should do something like this:
Thanks Markus, I can see the benefits of that kind of setup, especially with regard to SQL. I imagine with the drivers and ports behind the couch it can muffle the sound and may cause other issues. But the up-facing drivers aren't very practical - ESPECIALLY for a cabinet I'm trying to disguise :-)

I've been running my subs nearfield behind the couch for about a year now with MUCH success - best location for my subs in the whole room. I added the test MBM about 2 months ago.



As you can see they are all very close to the back of the couch and the sound (and feeling) is exactly what I'm looking for. I've been following the VibSensor & MBM threads for a while and this setup behind the couch is pretty common, especially where the goal is to increase Tactile Response which is one of the things I'm looking for. Since we use the term omni-directional to describe subwoofer sound, we know they're not as sensitive to boundaries and reflections, distance or location. Though I do understand that blocking the driver or port can cause problems. My couch is cloth not leather, so it's not a solid, and there will be some space between the cabinet and the couch (our couch has a sloping back and the cabinet will have a top with 1" overhang). So I don't think it will be an issue.

I've gotten a lot of inspiration from those threads and from my own personal preference and research that have led me to this design.
Many have had success with setups similar to what I'm building (most with separate components though).
Here are some examples of setups I have seen and used as inspiration

1. @lz7j (these are run facing the couch with the ports at chest level)


2. @More is Better (there is some distance here between the couch and the drivers, and the drivers extend above the couch with most others don't, but I believe this was just temporary)


3. @Raylon


4. @raynist


5. @SBuger (new & old)




Probably the one significant difference between these setups and mine is that in these examples the nearfield subs are supplemental to other subs in the room. In my setup the nearfield sub cabinet will be the primary LFE source (and only one for now).
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post #32 of 106 Old 02-05-2017, 12:46 PM
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Quote:
Originally Posted by Brazle View Post
up-facing drivers aren't very practical - ESPECIALLY for a cabinet I'm trying to disguise :-)
Get creative. You can cover them with fabric. Mount a metal mesh underneath for protection. Or build a bandpass sub (see attachment). Or...
The only important thing is to get the source as close as possible to your ears.
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post #33 of 106 Old 02-05-2017, 03:04 PM - Thread Starter
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Quote:
Originally Posted by markus767 View Post
... Or build a bandpass sub (see attachment). Or...
.
Out of curiosity.
1. On this bandpass sub, where is the mouth of the vent? I'm guessing it's at the top of the box facing forward toward the couch. Completely across the width of the box? If so that's interesting.
2. I like those drawings, what do you use to draw them?

Quote:
Originally Posted by markus767 View Post
The only important thing is to get the source as close as possible to your ears..
Makes sense, but for TR you would want the drivers facing your person/body.

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post #34 of 106 Old 02-05-2017, 03:12 PM
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@Brazle , thanks for the mention. Seems to be lots more nearfield sets ups around here than there used to be.

Cool build you have going here!! Oh the nearfeild ... I love NF and would never want to be without it again. It has me spoiled to say the least

As far as it being a bad I idea like markus767 was saying, I'd definitely have to disagree. That said though I've never tried my nearfields with the driver facing up so can't comment on that, but I have tried them with driver (and ports when I had ported subs) facing to the side as opposed to firing into the back of the couch. SQ may or may not sound better with drivers facing up vs into the back of the couch, but probably not by much if EQ'd the same. I can say though that it made a world of difference in TR and body pounding PR with the different orientations of the driver, with it firing into the back of your seat having the most powerful effect by a wide margin. Not even comparable actually, even though FR looked almost identical and sounded about the same.

IME so far with messing with the NF's with drivers facing into back of couch over the last 3 or 4 years, I've never thought it has ever sounded muffled. In fact, if I just run the NF's only, it can sound so super clean with a pretty decent FR (mainly no peaks).

Also for me, the main benefit of the nearfield sub is to maximize TR (tactile response) and PR (pressure response). I'm talking PR waves that hit your body that you can really feel, not the weight type of PR that feels like its pressuring up your ears.

If it were me I think I'd definitely go as planned with drivers and ports facing into the back of the couch with just enough room for driver excursion and not block the ports (so like a half and inch to and inch or so). With subs placed NF in this manor, it will give maximum TR and PR waves that hit the body, if this is what your after of course. Driver facing up will probably deliver as well, but I'd be surprised if it was as strong. Again, I've never tried driver facing up. This may or may not be a bad thing if its not as strong though. There is such a thing as too much distracting and localized TR that can come from drivers facing into your back if your not careful. IME, this can be tailored to personal taste though. I'm able to accomplish this by running multiple NF's (not just one directly behind me) and FF up front as well. This will allow you control how much each location contributes.

Since this will be your only sub location (sorry if I read this wrong and you will have other sub locations as well), if it did ever become to distracting with to much localizable TR etc, you could just move your sub box back a little so the drivers wont be as close or turn the gain down, or even both. IME, even moved back a couple of inches can make a huge difference in intensity.
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post #35 of 106 Old 02-06-2017, 12:06 AM
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Quote:
Originally Posted by Brazle View Post
Out of curiosity.
1. On this bandpass sub, where is the mouth of the vent? I'm guessing it's at the top of the box facing forward toward the couch. Completely across the width of the box? If so that's interesting.
2. I like those drawings, what do you use to draw them?
1. Correct
2. SketchUp

Quote:
Originally Posted by Brazle View Post
Makes sense, but for TR you would want the drivers facing your person/body.
Get a shaker. Much better than trying to make your couch rattle with a sub firing into it. With a shaker you can concentrate on getting the response at your ears right. The idea of near field sub(s) is to remove the room from the response. This effect gets lost once the driver is more than 1-2ft from the ear.

I'm using 2 ripole subs. This is the unsmoothed response across 3 seats (equalized to follow my house curve):



Waterfall – virtually no ringing in a room without bass traps (the ridges in the front are largely just the noise floor):

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post #36 of 106 Old 02-06-2017, 06:37 AM - Thread Starter
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@markus767 , do you have any pics of your setup? I'm curious how and where your subs are set up. I'm also curious what they look like.

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post #37 of 106 Old 02-06-2017, 10:28 AM
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Quote:
Originally Posted by Brazle View Post
Thanks Markus, I can see the benefits of that kind of setup, especially with regard to SQL. I imagine with the drivers and ports behind the couch it can muffle the sound and may cause other issues. But the up-facing drivers aren't very practical - ESPECIALLY for a cabinet I'm trying to disguise :-)

I've been running my subs nearfield behind the couch for about a year now with MUCH success - best location for my subs in the whole room. I added the test MBM about 2 months ago.



As you can see they are all very close to the back of the couch and the sound (and feeling) is exactly what I'm looking for. I've been following the VibSensor & MBM threads for a while and this setup behind the couch is pretty common, especially where the goal is to increase Tactile Response which is one of the things I'm looking for. Since we use the term omni-directional to describe subwoofer sound, we know they're not as sensitive to boundaries and reflections, distance or location. Though I do understand that blocking the driver or port can cause problems. My couch is cloth not leather, so it's not a solid, and there will be some space between the cabinet and the couch (our couch has a sloping back and the cabinet will have a top with 1" overhang). So I don't think it will be an issue.

I've gotten a lot of inspiration from those threads and from my own personal preference and research that have led me to this design.
Many have had success with setups similar to what I'm building (most with separate components though).
Here are some examples of setups I have seen and used as inspiration

1. @lz7j (these are run facing the couch with the ports at chest level)


2. @More is Better (there is some distance here between the couch and the drivers, and the drivers extend above the couch with most others don't, but I believe this was just temporary)


3. @Raylon


4. @raynist


5. @SBuger (new & old)




Probably the one significant difference between these setups and mine is that in these examples the nearfield subs are supplemental to other subs in the room. In my setup the nearfield sub cabinet will be the primary LFE source (and only one for now).
Nice collage of nearfield MBMs! I plan to add this to the first couple of posts in the MBM thread.
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post #38 of 106 Old 02-06-2017, 10:56 AM
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I would think that balancing TR and FR is going to be quite challenging with near field as the only source.
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post #39 of 106 Old 02-06-2017, 02:28 PM - Thread Starter
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Quote:
Originally Posted by 3ll3d00d View Post
I would think that balancing TR and FR is going to be quite challenging with near field as the only source.
Yes, we'll see. I've had all my subs directly behind the couch for almost a year now and I've been really happy with how it sounds and feels. I don't expect it to be too much of an issue. I'm happy to have strong TR. From what I've experienced so far the TR and FR have been pretty well matched.

Before I added my MBM test box I had a pretty dip in FR from 50Hz up in the bass (at least so I thought and turns out I was right). Here's the FR with MBM (gold) and without MBM (red):



Here is the TR graph without the MBM:



And here is the TR graph with the MBM:



So you can see adding the MBM brought my TR and FR between 50 and 100Hz up to matching levels with the response I was getting with only my subwoofers below 50Hz. They were doing great between 20 and 50Hz, not so much above there.
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post #40 of 106 Old 02-06-2017, 02:41 PM - Thread Starter
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I'm thinking about lowering the XO in my receiver (Pioneer VSX-94TX) to 50Hz, then running the MBMs off the combined signal output from the LR pre-outs instead of the sub pre-out.

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post #41 of 106 Old 02-09-2017, 08:35 AM - Thread Starter
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Quote:
Originally Posted by SBuger View Post
@Brazle , thanks for the mention. Seems to be lots more nearfield sets ups around here than there used to be.

Cool build you have going here!! Oh the nearfeild ... I love NF and would never want to be without it again. It has me spoiled to say the least

Since this will be your only sub location (sorry if I read this wrong and you will have other sub locations as well), if it did ever become to distracting with to much localizable TR etc, you could just move your sub box back a little so the drivers wont be as close or turn the gain down, or even both. IME, even moved back a couple of inches can make a huge difference in intensity.
Thanks @SBuger ,
Yea, NF has spoiled me too, and yet has me craving more :-)

Yes, only sub location. Those haven't been issues so far, but we'll see if anything changes with such a big cabinet. I'm not too worried about it though. You're right thought if it's "too much" I can easily turn down the gain or move it back a little.

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post #42 of 106 Old 02-09-2017, 10:39 AM - Thread Starter
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Yesterday was exciting (for me).

Got my UM18 in!!!



Man this thing is big :-)



It's really pretty, looks and feels very high quality.



Awesome!



Also, I spent some time making adjustments to my MBM test box too. I know I've said consistently that it was ~3 cubic feet or 2.9, but after measuring it yesterday, it was really 2.62 cubic feet (internal net). So a little smaller than I thought. Next step is to put the PA380 in smaller box to see how it sounds, see if it loses a lot of low-end, see if it gains punch or tightness. Really I'm feeling out the min-max of box dimensions for this driver. Dayton Recommends 1.55 cubic feet. So I started around 3 to try an oversize box. Now I've cut it down, almost exactly in half.



This box should be ~1.3 cubic feet. 1 port will have ~57Hz tune. 2 ports ~80Hz. I'm just using the same triangle ports 5"x5"x5"(L) as the original box. Actually I just cut the box in half and glued the back half of the box onto the front half backwards :-)

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post #43 of 106 Old 02-14-2017, 11:01 PM - Thread Starter
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Update #1

Tested my 1.3 cubic foot MBM and it lost of ton of low end. Between 100Hz and 75Hz there's a 15dB difference. It basically drops like a rock below 95Hz.
Here's a comparison between the 2.6 cubic foot box (blue = low tune, green = high tune) and the 1.3 cubic foot box (red).
(** edit see following posts for updated info, these graphs are junk)



And here's an extrapolation I did. Next test will be at 2.0 cubic feet. I hope this all makes sense, the black and purple lines are estimates for 1.55 cubic feet and 2.0 cubic feet respectively. Looks like 2.0 cubic feet will give me just the low-end extension I'm looking for - down to about 50-60Hz.




Update #2

And here is an even more final model of the final cabinet design. Got some bracing in there. This is with 2.0 cubic ft MBMs (ports are 1.5"x15"x5"L) and 11.0 cubic ft for the ULF (ports are 6"x6"x50"L - two ports).





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post #44 of 106 Old 02-15-2017, 03:48 PM
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Hi Brazle,

I really like your plans and testing so far. I look forward to your impressions when you get the final build up and running. I'm curious if there will be much difference sitting directly in front of the UM18 vs one of the PA380s.

What's the overall depth of your final cabinet design?

Will there be other subs in your room other than the NF MBM?

For the red trace in your latest graph with 1.3 cuft box, is this the 2-port (80 Hz), or the 1-port (57 Hz) tune?

Thanks,
Darrell
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post #45 of 106 Old 02-15-2017, 05:16 PM
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100 thunbs up for firing that 18 directly forward at the seating....just make sure it is centered on your seat...


I went from a 100 watt 10 incher to a 150 watt 12 incher to a 250 watt 12 incher...all subs.........the 250 watt 12 incher had a lot more kick than the 150 watt one.


The 18 should be scary to say the least.........with 3 12`s up front and the 250 watt 12 behind the seating, gun shots are disturbing/cring worthy even when you know they are coming....makes you flinch......

That cabinet will be shocking...better warn people with a weak heart first........

My meager set up raises the pulse rate pretty good and will startle people.......

That cabinet you have will be taking things to a different planet !!!!!!!!!!!!!!
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post #46 of 106 Old 02-15-2017, 05:35 PM
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post #47 of 106 Old 02-15-2017, 08:36 PM - Thread Starter
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Quote:
Originally Posted by darrellh44 View Post
Hi Brazle,

I really like your plans and testing so far. I look forward to your impressions when you get the final build up and running. I'm curious if there will be much difference sitting directly in front of the UM18 vs one of the PA380s.

Thanks! I am curious too. I really wanted to spread things out so the MBMs would cover the whole couch and the ULF would cover the whole couch too. For the ULF I have the UM18 in the middle and the ports on the sides, I think that will help. For the MBMs I think the slot ports will help. I have had just the single behind the couch for a while for testing and it is pretty even across multiple listening positions, not just directly in front of it. So I think It should be pretty even overall.

What's the overall depth of your final cabinet design?

Cabinet depth is 22". there will be a top that hangs over 1" on the front and the sides. There will be a little over hang on the back too, 1/2" - 1". The cabinet is 22"(D)x68"(L)x26"(H) and I'll be adding feet to the bottom (3-4") and the top will add 1-2".

Will there be other subs in your room other than the NF MBM?

Currently I don't plan to have other subs, but the cabinet will have the dual function of ULF and MBM. In the future I may possibly add dual subs L&R in the front stage.

For the red trace in your latest graph with 1.3 cuft box, is this the 2-port (80 Hz), or the 1-port (57 Hz) tune?

That is the 80Hz tune, but at the moment I think that trace should be disregarded, I believe I mistakenly left the 100Hz crossover active in the receiver for those measurements. (see following post)

Thanks,
Darrell
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100 thunbs up for firing that 18 directly forward at the seating....just make sure it is centered on your seat...

Thanks! That is the plan The ports behind the left and right sides of the couch should feel pretty nice too.


I went from a 100 watt 10 incher to a 150 watt 12 incher to a 250 watt 12 incher...all subs.........the 250 watt 12 incher had a lot more kick than the 150 watt one.


The 18 should be scary to say the least.........with 3 12`s up front and the 250 watt 12 behind the seating, gun shots are disturbing/cring worthy even when you know they are coming....makes you flinch......

That cabinet will be shocking...better warn people with a weak heart first........

My meager set up raises the pulse rate pretty good and will startle people.......

That cabinet you have will be taking things to a different planet !!!!!!!!!!!!!!
Thanks man! I really think it should make for an immensely satisfying experience. I really enjoy showing off my setup to friends and I think this is going to take it to a whole new level.

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Thanks1\]]!!11Q!

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post #48 of 106 Old 02-15-2017, 09:09 PM - Thread Starter
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Well, I feel like an idiot.

My first series of tests for the PA380 MBM in the 2.6 cu ft box was great. There were several settings I had to get right on my computer (turn off all windows audio enhancements, REW settings) and several settings on the receiver (no bass boost, levels correct, RCA Pre-Out from Right instead of Sub, Fronts set to Large, Subwoofer set to Off to disable the crossover, ** edit: also, make sure listening mode is set to PURE DIRECT).

Here is an overlay of the 3 box sizes, one trace per box size, each with both ports open which should yield the higher tune.



I did a whole series of tests with the PA380 in a 1.3 cubic foot box with poopie graphs. I thought the box was just too small and that's why there was no low-end.

Then I did a whole series of measurements in a 2.0 cubic foot box today. Guess what - STILL POOPIE GRAPHS! I could not figure out what was wrong, no matter which ports I had open, there was still a drop-off under 100Hz. Gah!!!! Not till after I looked at ALL the graphs of ALL my tests with the 1.3 and 2.0 boxes did I notice a pattern (duh, I obviously noticed there was a pattern, but I couldn't figure it out).



(**following paragraph has been edited, to reflect updated info)
Looking at these, it's obvious there is an EQ problem somewhere. On my receiver listening mode was 192kHz STEREO and it looked like the output was a pure STEREO signal with no EQ, I was certain the Sub out was disabled, so I figured the Fronts were getting a full-range signal and I thought the Crossover was completely bypassed. Guess I was wrong. So for all my tests of an MBM with a focus on 50-100Hz I had an active High-Pass Filter (around 90Hz) on the signal. LOL, like I said, I feel like an idiot. I guess I'm still not sure that's what the problem is, but I'm fairly certain.

So basically I wasted 3+ hours testing two boxes with junk settings :-( - lame ... Time to redo some measurements! :-)
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post #49 of 106 Old 02-16-2017, 09:24 AM
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Quote:
Originally Posted by Brazle View Post
Well, I feel like an idiot.

My first series of tests for the PA380 MBM in the 2.6 cu ft box was great. There were several settings I had to get right on my computer (turn off all windows audio enhancements, REW settings) and several settings on the receiver (no bass boost, levels correct, RCA Pre-Out from Right instead of Sub, Fronts set to Large, Subwoofer set to Off to disable the crossover).
Why did you need to switch to the right pre-out channel to run the sweep on the sub? Can't REW sweep the sub channel directly?
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post #50 of 106 Old 02-16-2017, 09:59 AM - Thread Starter
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Quote:
Originally Posted by darrellh44 View Post
Why did you need to switch to the right pre-out channel to run the sweep on the sub? Can't REW sweep the sub channel directly?
Good question. The main reason is I want to have a full range unaltered signal coming through the receiver. No high pass, no low pass, no boost, no cut, no eq. The purpose is to be able to measure the natural frequency response of the speaker as accurately as possible.

REW can definitely sweep the sub channel directly, but there will inevitably be a low pass filter at the least on that channel. The Low Pass frequency will depend on where you have the crossover set on the receiver. The highest mine goes is 200Hz, but there's only about an octave between 100 and 200Hz so it may even start cutting the signal as low as 100Hz, but I don't know. I'm not sure specifically how the crossover is applied in my receiver. So the easiest thing to do is bypass this issue completely by running the signal through the Right Pre-Out. With my receiver set to Pure Direct, this should guarantee a clean unaltered signal from the source (REW) through the receiver to the speaker.

And as it turns out this was my problem! The crossover was fine, no sub out on Stereo, BUT, the receiver was set to its default 192KHZ STEREO. I assumed this was a pure stereo setting, but APPARENTLY NOT. There's a clearly an 18dB cut between 90Hz and 60Hz with this setting active. I just do not understand why you would want a cut there. What a frikkin retarded setting.

So I changed the audio on the receiver from 192KHZ STEREO to PURE DIRECT and now my REW measurements are great again! I wish i had thought of that earlier.
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So with the 2.0 cuft chamber for the PA380s in your final design, what port tune will the slots give you?
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Great News! I finally got "correct" measurements from REW for all 6 MBM configurations. (see previous posts for details).
The driver is the PA380
These are the MBM configurations (all ported) I tested show below:

Box Size -- Ports* -- Tune (approx) -- (Tune per WinISD)
2.6cf ------ two ------ ~50Hz ---------- (57Hz)
2.6cf ------ one ------ ~36Hz ---------- (40Hz)
2.0cf ------ two ------ ~60Hz ---------- (65Hz)
2.0cf ------ one ------ ~42Hz ---------- (46Hz)
1.4cf ------ two ------ ~70Hz ---------- (78Hz)
1.4cf ------ one ------ ~50Hz ---------- (55Hz)

(*The box has two triangular ports 5"x5"x5". To change the tune I would just close one of the ports. Two ports = high tune, one port = low tune.)

Here are the WinISD comparisons
3 boxes with low tunes (one port open) - 1.4cf vs 2.0cf vs 2.6 cf



3 boxes with high tunes (two ports open) 1.4cf vs 2.0 cf vs 2.6cf



And here are my REW Measurements
3 boxes with low tunes (one port open) - 1.4cf vs 2.0cf vs 2.6 cf



3 boxes with high tunes (two ports open) 1.4cf vs 2.0 cf vs 2.6cf



And here is a comparison of each box for its low and high tune (one port vs two ports open)
1.4 cf box



2.0 cf box



2.6 cf box



Conclusions to come :-)
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http://www.carstereo.com/help/Articles.cfm?id=31

I found this is pretty close for figuring out a slot port or square ports. WINISD makes them a little long and the tune ends up being lower.
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post #54 of 106 Old 02-16-2017, 03:21 PM - Thread Starter
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Quote:
Originally Posted by darrellh44 View Post
So with the 2.0 cuft chamber for the PA380s in your final design, what port tune will the slots give you?
Quote:
Originally Posted by bscool View Post
http://www.carstereo.com/help/Articles.cfm?id=31

I found this is pretty close for figuring out a slot port or square ports. WINISD makes them a little long and the tune ends up being lower.
I think the MBM box volume in the final cabinet design will end up being slightly larger; 2.2-2.3 cu ft.

The 1.5"x15" slot port I have designed at 5" long gives me a box tune very close to 55Hz (maybe slightly lower), that is using both WinISD and the carstereo calculator (thanks @bscool ). That's pretty much what I'm looking for. Low enough to get some fat mid-bass and high enough to get the port velocity up in the 50-100Hz range.

I hope the PA380s keep me happy, BUT, I'm keeping the option open to put a different driver in the MBM cabs if the PA380s aren't making me happy. This is part of the reason I'm sticking with the larger 2.0+cu ft size. Other options include: Dayton PA385-S, Dayton RSS390HO, Alpine Type R 15", Eminence 15", possibly even the woofer from the DIYSG Titan-615. Most of these drivers will perform better in a larger box, even for MBM duties.

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post #55 of 106 Old 02-17-2017, 05:09 AM
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Quote:
Originally Posted by bscool View Post
http://www.carstereo.com/help/Articles.cfm?id=31

I found this is pretty close for figuring out a slot port or square ports. WINISD makes them a little long and the tune ends up being lower.
i am wondering if that is just for car subs. or if it also applies to home subs ?

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i am wondering if that is just for car subs. or if it also applies to home subs ?
It applies to both equally, the physics stays the same, so there is no difference in modeling for enclosure volume, port size & length, tune, port velocity or anything really.

The difference comes with the volume of the space you're playing in - cabin gain vs room gain. Cars' much smaller volumes generally have much larger effect here.

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yeah, i didn't know if perhaps they took the smaller room (car) into account. or if it even made a difference.

one of my problems now, is figuring out what round ports i need. looks like this will tell me. thanx
my other problem, idk what box i can fit.

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post #58 of 106 Old 02-19-2017, 09:55 PM - Thread Starter
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Just done a little cutting over the last few days.
Got several of the main pieces cut between Home Depot and myself. Front, sides and both back baffle pieces. The rest is ready to cut.



And then I started cutting out some of the second baffle piece. This will be on the inside, glued to the back piece as the main baffle. I'll glue them together and then cut out the circles with recesses for the drivers.



The main reason I wanted to do this is for weight savings, I'm kind of worried about how heavy the final cabinet will be. That's why I switched from MDF to Arauco Sanded Plywood and that's why I'm doing this weight reduction on the interior double baffle. I understand not everyone will agree with this step risking reduced cabinet stiffness for weight reduction. And I know a solid double baffle would be even stiffer. But this is what I'm doing, I'm hopeful and confident this second baffle frame support will make the cabinet sufficiently stiff. I've been using the PL510 Wood adhesive. Is that the PL everyone is using? Or are people using the PL Premium?

Here are a few pics of process cutting out the second baffle.





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post #59 of 106 Old 02-19-2017, 10:44 PM
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The weight certainly picks up with multiple drivers all i one box. That may be your friends, the combined weight and construction may give you a very solid and rigid structure.
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post #60 of 106 Old 02-23-2017, 08:59 PM - Thread Starter
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Just wanted to post some pics of progress from this past week.

I learned that you can't have too many clamps, and I was really happy with how nice the circles turned out with the router. But the router is very slow work, so I did the outer circles with the router and the inner circles with a jig saw, much faster and you don't see them anyway because they're behind the driver.

Glued and clamped the baffles together



Cut the first hole *with 0.5" recess. Center hole for the UM18



Starting with 0.5" recesses for the PA380s. Router jig shown.



Three holes cut and one pic with the UM18 test fit :-)



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