Wow only 713 liter design.
Like I said, size is a choice. I could probably make it work in half the volume but it would take a high voltage amp to move it. On the other hand, when you don't need a hpf you don't need a boatload of voltage either so it depends on the design goals and how it's going to be used.
You can use a hpf if you want, it's just not needed for excursion control.
Personally I'd use one anyway, but a few hz below the excursion peak, a few hz lower than where you would usually put it. That will keep the low knee intact (no bass loss) but filter out power below that to keep thermal issues in check. No point in blasting it with power below the low knee.
As far as I'm concerned the distortion reduction is a secondary bonus, the thermal issue is what I would be worried about. Besides, there's not too much below 20 hz in most music, and it's only special effects in movies down that low, and I don't much care how much distortion the special effects have, but still I'd run a hpf just to keep the heat out below the low knee.
Personally I'd use one anyway, but a few hz below the excursion peak, a few hz lower than where you would usually put it. That will keep the low knee intact (no bass loss) but filter out power below that to keep thermal issues in check. No point in blasting it with power below the low knee.
As far as I'm concerned the distortion reduction is a secondary bonus, the thermal issue is what I would be worried about. Besides, there's not too much below 20 hz in most music, and it's only special effects in movies down that low, and I don't much care how much distortion the special effects have, but still I'd run a hpf just to keep the heat out below the low knee.
Dave,
I'll just answer your questions here.
The large Sundown surround I have a hunch might be problematic in horns with high compression ratios. You will have to factor in the inductance effects into the simulating if you want your build to mirror what you are simulating also. Otherwise your great simulation will give you the warm and fuzzy, but will have little to do with the sub you built. JAG can show you how to make the sim match the driver measurements a lot closer which will help but there is still a bit of guess work in there. The applied power for example gets thrown off a bit. You can back calculate it though. Back to the surround. This is part of what I was talking about in earlier posts about it being time to look at actual build logistics. Look at the mechanical drawings from Sundown for the 18" driver and surround. The surround protrudes way above the frame. I believe more than 45mm. The driver is said to be capable of 50mm xmech which will push the surround out quite a bit further at full excursion if ever used. From there you must consider that you want a significant amount of space from the potential surround position during xmech to the wood. If you start looking at minimum cab widths to fit an 18.5" framed driver and clear the driver excursion potential with plenty of room to spare you'll find a minimum S2 that is somewhat realistic to use with it. I also have some concerns about potential surround cavitation or perhaps shifting laterally during the high pressures inside a horn throat. Those surrounds have a large straight wall and are very tall. It may be that the drivers would be perfectly fine but I'd shoot for a moderate to low throat compression with that surround. I'd also be surprised if the excursion of these drivers could be used in the bandwidth of the horns you've been looking at without an absolutely massive amplifier. JAGs 560L FLH was speculated with a 165v amp already. I'd be surprised if they were more sensitive or efficient than the pro drives either.
At this point I really think you need to decide on a cabinet size and dimensions that works for you and stick with it and start working towards an actual design and fold. As JAG mentioned this is slowly creeping and is now up over 700L when it started out around 500. Paper racing always ends that way. Just a few more liters here and there. FYI in order to fit a 700L horn you are probably looking at something around the size of a 12pi basshorn. 45x45x26-28". That's a big cabinet.
I'll just answer your questions here.
The large Sundown surround I have a hunch might be problematic in horns with high compression ratios. You will have to factor in the inductance effects into the simulating if you want your build to mirror what you are simulating also. Otherwise your great simulation will give you the warm and fuzzy, but will have little to do with the sub you built. JAG can show you how to make the sim match the driver measurements a lot closer which will help but there is still a bit of guess work in there. The applied power for example gets thrown off a bit. You can back calculate it though. Back to the surround. This is part of what I was talking about in earlier posts about it being time to look at actual build logistics. Look at the mechanical drawings from Sundown for the 18" driver and surround. The surround protrudes way above the frame. I believe more than 45mm. The driver is said to be capable of 50mm xmech which will push the surround out quite a bit further at full excursion if ever used. From there you must consider that you want a significant amount of space from the potential surround position during xmech to the wood. If you start looking at minimum cab widths to fit an 18.5" framed driver and clear the driver excursion potential with plenty of room to spare you'll find a minimum S2 that is somewhat realistic to use with it. I also have some concerns about potential surround cavitation or perhaps shifting laterally during the high pressures inside a horn throat. Those surrounds have a large straight wall and are very tall. It may be that the drivers would be perfectly fine but I'd shoot for a moderate to low throat compression with that surround. I'd also be surprised if the excursion of these drivers could be used in the bandwidth of the horns you've been looking at without an absolutely massive amplifier. JAGs 560L FLH was speculated with a 165v amp already. I'd be surprised if they were more sensitive or efficient than the pro drives either.
At this point I really think you need to decide on a cabinet size and dimensions that works for you and stick with it and start working towards an actual design and fold. As JAG mentioned this is slowly creeping and is now up over 700L when it started out around 500. Paper racing always ends that way. Just a few more liters here and there. FYI in order to fit a 700L horn you are probably looking at something around the size of a 12pi basshorn. 45x45x26-28". That's a big cabinet.
There's a lot of really good points in Josh's post. The surround is a big issue, on some of those drivers it's so big it would choke out the horn path unless it's well recessed into the chamber by about 3 inches so the surround doesn't poke out into the horn path at all, which is kind of silly. Hint - there's at least one Sundown driver that has a lot of excursion but doesn't have a silly large surround - look for drivers like that.
The power issue - as you can see in the sim I sent you, the drivers get about 2250 watts each, but the horns are bigger than your biggest sim and the low knee is close to 20 hz, so that eats up the excursion without ridiculously high power demands. Tune higher and use a smaller box and amp voltage rail requirements go through the roof.
And the compression ratio comment is on point too. One thing I forgot to mention in the notes I sent you is that the compression ratio in that design is less than 2.5:1. You want to keep that low when you can, especially if you use one of those drivers with the silly huge wide surrounds like the HST.
And the size comments are about right too. My design is huge but it doesn't have to be moved much. I'm planning on probably 600 lbs per cab and almost 65 cubic feet gross per cab (dual drivers per cab so divide by 2 for single driver cabs).
You really do need to have solid goals and restrictions in place, otherwise things get out of hand really fast. And it only happens a few liters at a time, it happens incrementally so that you don't even notice until it's too late and you created a monster.
The power issue - as you can see in the sim I sent you, the drivers get about 2250 watts each, but the horns are bigger than your biggest sim and the low knee is close to 20 hz, so that eats up the excursion without ridiculously high power demands. Tune higher and use a smaller box and amp voltage rail requirements go through the roof.
And the compression ratio comment is on point too. One thing I forgot to mention in the notes I sent you is that the compression ratio in that design is less than 2.5:1. You want to keep that low when you can, especially if you use one of those drivers with the silly huge wide surrounds like the HST.
And the size comments are about right too. My design is huge but it doesn't have to be moved much. I'm planning on probably 600 lbs per cab and almost 65 cubic feet gross per cab (dual drivers per cab so divide by 2 for single driver cabs).
You really do need to have solid goals and restrictions in place, otherwise things get out of hand really fast. And it only happens a few liters at a time, it happens incrementally so that you don't even notice until it's too late and you created a monster.
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Had to edit after posting.
I wont be using the HST in a horn. In sims it looked great. While I have said I wanted a "X," size design it only got bigger because we changed from con to par. Then it was a matter of improving 25-45hz saddle.
All the designs that got larger were mainly TB46's, Sine143 or JAG's when I tried to lengthen the horn to have a lower Hpass. Then realized the size went to 700 pretty quick.
SO as I said before 670l is the biggest it has gotten. I am not going bigger than that. I was merely trying to get this design down a bit in size while keeping most of the same BW goals.
Yes I know it has grown in size but that also was because I didnt want to have a horn that needed 3x's RMS to hit Xmax. So it had to grow. I also had to change the size restriction after altering CON to PAR.
SO as I would saying I own the SW152 already. This is the driver I will use regardless. I was just simulation many other drivers to see what SPL potential they had. I would most likely buy a 21IPAL for this design before HST. They are the same price.
And I will be using a Hpass regardless on all my designs. Even in my simulation with the HST it needed on at 23hz 3rd order.
Appreciate all the help so far. I guess it is difficult in understanding what is in ,y mind when asking questions. I understand why the need for a Hpass. I understand the high surround possible issue also. I was just wanting to hear someone else's opinion to on the surround to confirm what I was thinking. And that happened.
I know distortion will be high if running these designs way below their tune and really high excursion. Again that wont be happening.
Ricci rings out every bit of performance he can from his designs. I cant afford to do that with my amplifiers. I will always be amp limited when using this FLH.
Here is my latest design. I already uploaded the input page earlier.
SO again thanks to everyone so far.
JAG I will have a look now at your email.
I wont be using the HST in a horn. In sims it looked great. While I have said I wanted a "X," size design it only got bigger because we changed from con to par. Then it was a matter of improving 25-45hz saddle.
All the designs that got larger were mainly TB46's, Sine143 or JAG's when I tried to lengthen the horn to have a lower Hpass. Then realized the size went to 700 pretty quick.
SO as I said before 670l is the biggest it has gotten. I am not going bigger than that. I was merely trying to get this design down a bit in size while keeping most of the same BW goals.
Yes I know it has grown in size but that also was because I didnt want to have a horn that needed 3x's RMS to hit Xmax. So it had to grow. I also had to change the size restriction after altering CON to PAR.
SO as I would saying I own the SW152 already. This is the driver I will use regardless. I was just simulation many other drivers to see what SPL potential they had. I would most likely buy a 21IPAL for this design before HST. They are the same price.
And I will be using a Hpass regardless on all my designs. Even in my simulation with the HST it needed on at 23hz 3rd order.
Appreciate all the help so far. I guess it is difficult in understanding what is in ,y mind when asking questions. I understand why the need for a Hpass. I understand the high surround possible issue also. I was just wanting to hear someone else's opinion to on the surround to confirm what I was thinking. And that happened.
I know distortion will be high if running these designs way below their tune and really high excursion. Again that wont be happening.
Ricci rings out every bit of performance he can from his designs. I cant afford to do that with my amplifiers. I will always be amp limited when using this FLH.
Here is my latest design. I already uploaded the input page earlier.
SO again thanks to everyone so far.
JAG I will have a look now at your email.
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I'll tell you where it ends. 5400 liters. That's what it takes to be fully horn loaded at 30 Hz with 21SW152's. Six 900 liter cabs.
Actually, the LAB15's model quite well - allowing you to use twice as many smaller boxes.... in theory. But if they are not rigidly fixed together you'll lose something. Maybe not much, but it will still be less output. And I'm fairly sure there will be more output at 1000 watts average power into a 21SW152 compared to two LAB15's, which will be letting the magic smoke out by then.
Yes sir.
Here's what the System Design With Driver tool (Leach's math) says about a 30 hz horn with 6 drivers. Shown with 24000 watts (4000 per driver) and no filters. Fun stuff. Personally I'd split it into 8 Labhorn size cabs and use cheaper 18 inch driver like the 18tbw100 but that's just preference and budget considerations. (Actually while we are daydreaming I'd tune at 27 and do 12 cabs but that's just me.)
An externally hosted image should be here but it was not working when we last tested it.
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I sent it a couple hours ago already to the address you provided. If you don't see it check your junk mail.
I don't think anyone has been able to answer that question yet. All the 'good designs' approach 4:1. The one I've been fooling with is 3.73. The 18's will take it - the $64k question is will the 21's?
I haven't committed to any new designs myself - the initial thoughts are to build something new that can out-do a stack of 8 lab horns by somewhere in the neighborhood of 10dB using some modern tech. The basic building block is either a 900 liter box with the 21 or a 700 liter with the the 18TBW (which I have on hand to experiment with). Each has their advantages and disadvantages. Whether the driver is strong enough is one of the considerations.
Funny thing about this project is that I'm starting with the mains this time - not the subs. I have a little time.
I haven't committed to any new designs myself - the initial thoughts are to build something new that can out-do a stack of 8 lab horns by somewhere in the neighborhood of 10dB using some modern tech. The basic building block is either a 900 liter box with the 21 or a 700 liter with the the 18TBW (which I have on hand to experiment with). Each has their advantages and disadvantages. Whether the driver is strong enough is one of the considerations.
Funny thing about this project is that I'm starting with the mains this time - not the subs. I have a little time.
A 700 liter based on the tbw would be really cool, mostly because of the attractive price of the driver and AFAIK more optimised driver for flh use compared to the sw152? I wonder how a stack of 6 tbw loaded flhs would compare to a 6 stack of labhorns.
Hi wg_ski,
Thanks for the insights in Post #238. I already mentioned this link in Post #60:
http://www.diyaudio.com/forums/subwoofers/190635-th-18-flat-35hz-xoc1s-design-49.html
Do you think that type of throat treatment is necessary for the 21SW152 in an OD-FLH?
Regards,
Thanks for the insights in Post #238. I already mentioned this link in Post #60:
http://www.diyaudio.com/forums/subwoofers/190635-th-18-flat-35hz-xoc1s-design-49.html
Do you think that type of throat treatment is necessary for the 21SW152 in an OD-FLH?
Regards,
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