That's why I said the TH and BP6 would probably sound better than the TL because the driver is inside the enclosure.
The CSA is 16"W x 9"D. The Kicker 08SL7154 has an 8 11/16" mounting depth. The goal was use the smallest CSA with some breathing room for the voicecoil. I could have used 8.75" since the L7 has an alternate vent setup.
Also, I wouldn't play to 100hz. I'm an 80hz low pass type of guy. You guys are all PA. I'm CA & HT and like using PA equipment.
The 100 Hz "cliff" bothers me not because I'd want to cross over the sub at 100 Hz, but because I try to get the sub's response to be smooth for up to an octave above where I plan to filter it. This will allow me to use simple x-overs and shallower slopes and get a smoother response through the x-over region. This is probably another reason why I tend towards ODTLs these days with the driver mounted about 1/3rd down the line.
Yeah, otherwise, there’s no XO slope that’ll fix enough of that to be unheard or influencing what you want to hear. my ears dwell on this junk once you can sense it
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yummy💪🏻💪🏻is it powered by the dayton audio sa1000 below the Tv?
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Wow, I didn't realise that it's been over a year since I started this thread ..!
Short version: I had someone build the ODTL (now christened POC7), and I've put it through several listening tests. At first, I was not as impressed as I expected to be with the results, but a little bit of damping in the S1 region improved things significantly.
There's a page about the build here - https://www.diysubwoofers.org/projects/other/POC7/
As I expected, the ODTL alignment is much better for mid-bass transition than a TH, as there are no wild phase and output variations to deal with in the 100 Hz ~ 200 Hz region. See image below for example (POC3 TH and POC7 ODTL driven with 200Hz 6dB LP filter and main speakers driven full range, i.e. a cheap 2.1 system). Look what's happening in the 100 Hz - 200 Hz mid-bass transition region. The ODTL (red curve) stomps all over the TH (blue curve). Note that this wasn't an accurate FR measurement - just one to show the difference in performance between the two setups. The TH does produce a bit more bass at lower frequencies, but it's a larger box and the 100 Hz - 200 Hz region is a bit of a mess. Yes, you can reduce the mess by using sharper cutoff slopes on the TH and the tops, but sharper filters can introduce issues of their own.
The image below shows how the impedance curve of an ODTL varies compared to a TH. Note that there are no variations in the 100 Hz to 200 Hz region in the ODTL's curve (red). Another sign that there aren't going to be any phase issues in this crossover region to deal with.
Overall, I'm quite happy with the results, but I think this type of build might be difficult to translate to other drivers - that biggest issue being that resizing this type of ODTL fold might end up with the depth of the sections being too low to fit the driver into the box. It can work for cheaper drivers with largish Vas/Qts ratios like the Dayton PA310 and the Kappalite 3012LF, but then output is going to be limited. The ODTL fold that I used for my POC6 and my "Boom Unit" build is quite a bit more flexible and can be used for many drivers, and it's probably the type of fold that I'm going to use for my next build which is still in the planning stages.
Short version: I had someone build the ODTL (now christened POC7), and I've put it through several listening tests. At first, I was not as impressed as I expected to be with the results, but a little bit of damping in the S1 region improved things significantly.
There's a page about the build here - https://www.diysubwoofers.org/projects/other/POC7/
As I expected, the ODTL alignment is much better for mid-bass transition than a TH, as there are no wild phase and output variations to deal with in the 100 Hz ~ 200 Hz region. See image below for example (POC3 TH and POC7 ODTL driven with 200Hz 6dB LP filter and main speakers driven full range, i.e. a cheap 2.1 system). Look what's happening in the 100 Hz - 200 Hz mid-bass transition region. The ODTL (red curve) stomps all over the TH (blue curve). Note that this wasn't an accurate FR measurement - just one to show the difference in performance between the two setups. The TH does produce a bit more bass at lower frequencies, but it's a larger box and the 100 Hz - 200 Hz region is a bit of a mess. Yes, you can reduce the mess by using sharper cutoff slopes on the TH and the tops, but sharper filters can introduce issues of their own.
The image below shows how the impedance curve of an ODTL varies compared to a TH. Note that there are no variations in the 100 Hz to 200 Hz region in the ODTL's curve (red). Another sign that there aren't going to be any phase issues in this crossover region to deal with.
Overall, I'm quite happy with the results, but I think this type of build might be difficult to translate to other drivers - that biggest issue being that resizing this type of ODTL fold might end up with the depth of the sections being too low to fit the driver into the box. It can work for cheaper drivers with largish Vas/Qts ratios like the Dayton PA310 and the Kappalite 3012LF, but then output is going to be limited. The ODTL fold that I used for my POC6 and my "Boom Unit" build is quite a bit more flexible and can be used for many drivers, and it's probably the type of fold that I'm going to use for my next build which is still in the planning stages.
Here's a picture of POC7 next to POC3. POC7 is slightly deeper, by about 1/2" or so. But it's noticeably shorter. The width of both speakers is about the same. I've added an old speaker grille from a car audio build that I did years ago to protect the driver's cone, until I come up with something more elegant. Note to self - I need to make the rebate around the driver baffle a bit deeper because the combination of the driver mounting flange and the grille is definitely more than 0.75". And yes, the carpet-covered grill does affect the output a little, but not by much.
Hello Brian,
Why not going Manifold? or others 6th order bandpass Parallel design. There are ways to improve cooling and port noise for them.
You can get low frequencies advantages of TH and extended range as ODTL to reach 200Hz. You could plan POC8 for 2025.
Merry xmas.
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POC7 was my first "straight TL" that I built, and I chose this alignment really as an experiment to see what the actual advantages and disadvantages of such an alignment would be, compared to what any theory would suggest, among some other things. Turned out that I was mostly right about everything 🙂.
The manifold approach looks like a decent idea. Form factor might be an issue though, as one of the main requirements of any of my POCs is that it should be able to fit in my car's trunk, which does put some limitations on box dimensions. Plus, the shape suggests that it might not be the easiest box to move around without assistance (a problem that I ran into with the THAM-style POC2.
My next planned build (for the moment) is based on two 12" drivers in separate ~42 Hz ODTL boxes, both of which should be able to fit into my car's trunk, leaving enough space for the tops to be included. It won't be a "POC", as I've built this type of layout before. But they should outperform them. No replacement for displacement 🙂.
The manifold approach looks like a decent idea. Form factor might be an issue though, as one of the main requirements of any of my POCs is that it should be able to fit in my car's trunk, which does put some limitations on box dimensions. Plus, the shape suggests that it might not be the easiest box to move around without assistance (a problem that I ran into with the THAM-style POC2.
My next planned build (for the moment) is based on two 12" drivers in separate ~42 Hz ODTL boxes, both of which should be able to fit into my car's trunk, leaving enough space for the tops to be included. It won't be a "POC", as I've built this type of layout before. But they should outperform them. No replacement for displacement 🙂.
...and here's what the carpet-covered grille does to the output...
Some background history - years ago (1996), before I had access to any real measuring equipment, I did a car audio build where the subwoofer was a fiberglass enclosure in the spare tire well that hosted two JBL 1200GTs that was vented to 35 Hz (as per JBL's specifications). The floor of the car's trunk was raised about three or four inches to accommodate the enclosure and the amplifiers that were mounted on the sides, below dress panels to make the whole install very stealth. However, the cones of the two 12" drivers were distinctly visible and unprotected, so my "hack" to address this was to cover some metal grilles with matching carpet and use those to protect the drivers. I figured that if bass could make it all the way through the rear seat in my sedan, a layer of carpet on the grille certainly wasn't going to stop it. And the result sounded pretty good.
Well, I found one of those old grilles when I was looking around in storage for a way to protect the driver in POC7, so I mounted it up and then took some measurements with DATS and REW. The measurements show a drop in the impedance peaks (likely due to lowered Qms), a minor drop in driver response above Fb and a slightly increased drop in driver output below Fb. That it damps driver motion below Fb might actually be an advantage 🙂.
Some background history - years ago (1996), before I had access to any real measuring equipment, I did a car audio build where the subwoofer was a fiberglass enclosure in the spare tire well that hosted two JBL 1200GTs that was vented to 35 Hz (as per JBL's specifications). The floor of the car's trunk was raised about three or four inches to accommodate the enclosure and the amplifiers that were mounted on the sides, below dress panels to make the whole install very stealth. However, the cones of the two 12" drivers were distinctly visible and unprotected, so my "hack" to address this was to cover some metal grilles with matching carpet and use those to protect the drivers. I figured that if bass could make it all the way through the rear seat in my sedan, a layer of carpet on the grille certainly wasn't going to stop it. And the result sounded pretty good.
Well, I found one of those old grilles when I was looking around in storage for a way to protect the driver in POC7, so I mounted it up and then took some measurements with DATS and REW. The measurements show a drop in the impedance peaks (likely due to lowered Qms), a minor drop in driver response above Fb and a slightly increased drop in driver output below Fb. That it damps driver motion below Fb might actually be an advantage 🙂.
What are the maximum dimensions to consider as contains: L x W x D? Why not the same size of POC#3 please, share the sizes, in this way you could directly compare with it and it fits your car space, if you remains with Tucson.
Can I consider the driver Dayton PA310 8 ohm?
Don't know when my Hornresp will work again but once it work I can suggest you a proposal for a future POC, if you consider good enough.
POC#3 Hornresp data:
POC3 is 22" x 33.5" x 14.5" (I added 0.75" ply to the top and bottom of the TH to give it a bit more strength and reduce panel flex). The maximum size I can work with is 22" x 38" x 14.5", which basically limits me to 12" drivers.
The output of the POC3 with the PA310 driver was not enough to keep up with my tops (not surprising, since it has only 5mm Xmax).
Replacing it with the Kappalite 3012 LF improved the output a bit, but not as much as I would have liked.
POC7 is smaller than POC3 and provides slightly less maximum output.
The next build I'm planning involves going with two 12" drivers in two separate MLTL boxes that take up the 22" x 38" x 14.5" available. The driver I'm looking at for the job is the Dayton Odeum 12LF, which has the same Xmax rating of the Kappalite.
The output of the POC3 with the PA310 driver was not enough to keep up with my tops (not surprising, since it has only 5mm Xmax).
Replacing it with the Kappalite 3012 LF improved the output a bit, but not as much as I would have liked.
POC7 is smaller than POC3 and provides slightly less maximum output.
The next build I'm planning involves going with two 12" drivers in two separate MLTL boxes that take up the 22" x 38" x 14.5" available. The driver I'm looking at for the job is the Dayton Odeum 12LF, which has the same Xmax rating of the Kappalite.
I've been following your MLTL experiments and can hope I can try my own builds in the new year...
I'm curious for your comments comparing the straight MLTL layout to tapered MLTL (ie POC#6)
Ie, what are pro/con of each and what has informed you to pursue a pair of tapered for next build?
I'm curious for your comments comparing the straight MLTL layout to tapered MLTL (ie POC#6)
Ie, what are pro/con of each and what has informed you to pursue a pair of tapered for next build?