Post #160
Hi chrapladm,
E.g.: take sine143's drawing from Post #137, it already has a larger mouth area, so convert it back into a simulation, and see what that will do for you. Then you optimize that simulation, and see how you'll have to change the box....
Regards,
P.S.: If you haven't read the papers by Dr. Bruce Edgar yet, volvotreter has them on his excellent download page:
http://volvotreter.de/dl-section.htm
Maybe start w/ the Show Horn.
Hi chrapladm,
E.g.: take sine143's drawing from Post #137, it already has a larger mouth area, so convert it back into a simulation, and see what that will do for you. Then you optimize that simulation, and see how you'll have to change the box....
Regards,
P.S.: If you haven't read the papers by Dr. Bruce Edgar yet, volvotreter has them on his excellent download page:
http://volvotreter.de/dl-section.htm
Maybe start w/ the Show Horn.
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Here is my input. So do I need to add in S5?
Also I apologize but I am not knowledgeable enough to look at Sine's drawing and convert it into a Hornresp input screen. I can take what he suggested as parameters in his post and see what that amounts to.
If I could look at a drawing and convert that to a Hornresp input I would be able to see the fold in my head and going from there would be easy. I feel.
I can agree with much of this. (The graphs in particular) You have contended that the filters are vital and they are of course, however the data without the filters is just as if not more so. The raw system performance cannot be forgotten. There are things which must be looked at that I view as absolutely crucial. The filters used are important but they have limitations. The maximum voltage potential from the amp and how the sub responds to it cannot be forgotten as if it will never occur.
Hopefully we can agree on these things as fact.
1.)The impedance curve is not changed by the filters.
2.)The voltage sensitivity of the system is not changed by the filters.
3.) The system efficiency is not changed by the filters.
4.)The driver excursion profile with a specified voltage input from the amplifier is not changed.
5.)The maximum excursion limited output is not changed by the filters.
6.)The maximum voltage limited output is not changed by the filters.
7.)The maximum voltage available from the amplifier is not changed.
Moving from there...A few more facts from the simulations we've both done.
1.) The minimum impedance of the FLH is located around 34Hz and 73Hz in the pass band. It is about 3.5 ohms.
2.) If we set 20mm excursion as the clear overload point of the 21sw152 driver the FLH sim will reach 20mm excursion at 50Hz, which is the excursion peak in the upper bandwidth, at about 165 volts. (This is the input voltage we were using for the FLH in order to maximize its potential in the comparison. We can completely forget about using more voltage than this.)
3.) 165 volts into the FLH at 34Hz produces 7878 watts input according to HR, 5200w at 40Hz and 7630w at 73Hz.
Since we know #1-#7 from above are true, that the filters do not change the maximum voltage available from the amplifier, nor the drivers efficiency, sensitivity or excursion in response to a particular electrical signal and we also know that 165v input will produce the specified 20mm excursion limit at 50Hz, we also know that at minimum a 165 volt source would need to be used to achieve this amount of output shown from the system. The filters used can modify the incoming signal and pad it down a bit but the amplifier must be capable of at least the 165v amount of voltage in order to produce the output levels shown over some parts of the bandwidth in the comparison.
This is why I said it was not realistic in my opinion to use an amplifier capable of much more than 165v into this FLH design. Even that much may be pushing it depending on the user and content. Anyone who has done sound reinforcement, PA work or been in a speaker company that sells finished products to consumers will say that while the filters may make it look like the subwoofer will never receive the full 165 volts from the amplifier, other than over the small bandwidth wanted, in practice, if it is there as potential in the amplifier, it will get used, so you must plan that the system will receive the full brunt from the amp over it's full intended bandwidth at least briefly without damage. In this case below 30Hz where the amount of filtering has become very steep with a 3rd or 4th order used typically it probably will not be an issue as most of the hottest bass is above the high pass anyway. However the LPF used on the FLH to flatten the upper end is shallower and only providing a few dB of attenuation over a large part of the middle of its bandwidth. No matter how powerful the bass system invariably it will get pushed to the limit as people do. 40-80Hz is really the MEAT of the bass bandwidth for cabs like this. If the system after filtering has maximum voltage from the amplifier over the range between 40-50Hz this area will clip first. You can't assume that the level will get turned down because of a few flashes of the clip lights. Despite what Akabak shows in the power graph after filtering, if you have 165 volts worth of amp connected to the speaker the potential is there for nearly 7 to 8Kw into the min impedances at 34Hz and 73Hz (disregarding coil heating effects)which are smack in the wheelhouse of the sub and the driver is out of excursion at 50Hz and at 30Hz. That is a whole lot of heat to dissipate even briefly for this driver. If you use limiting to keep the voltage from the amplifier reduced then you lose the headroom of having that much voltage on tap. This is the reason why I did not agree with the much higher voltages used over a small bandwidth indicating an even more powerful amplifier potential which would have a real chance of causing damage in short order. I would recommend an amplifier equivalent to no more than 120volt into 4ohms capability to the Othorn for the same reasons and for this FLH I'd personally call a 165v amplifier the upper limit.
Hi chrapladm, a few lay comments...as I know next to nothing about design....but I have played with prosound boxes for home use, particularly outdoors, for a number of years.
I wouldn't be concerned with thermal issues at all for home use....
..unless it's the heat from local law enforcement !
I live in a rural area with understanding neighbors, but damn bass travels huh ?
Cops come about once every summer...
I run labsubs which of course have eminence drivers with now antiquated thermal capacity. And I still can't imagine getting into thermal trouble even using a bridged qsc3402 on each box.
I just plain don't get to play that loud that long for home use.
I did get ginned up to try W Parham's cooling plug idea for the lab 12 drivers once. So I put temp probes on the drivers to see if it was really worth the effort....I'd be in jail before I needed cooling !!
If you go the FLH route 45x45x22.5 handles really easy despite it's size.
And i noticed some of the guys talking about the need to couple boxes to smooth out ripple (which is well known to be the case with the labsubs.)
Here's a link to some simple meas I took of 1, 2, and 4 boxes. (2 lab, 40 hz, should have been 94.2 not 64.2)
Pairing true sub with TurboSound 718
Best, mark
I wouldn't be concerned with thermal issues at all for home use....
..unless it's the heat from local law enforcement !
I live in a rural area with understanding neighbors, but damn bass travels huh ?
Cops come about once every summer...
I run labsubs which of course have eminence drivers with now antiquated thermal capacity. And I still can't imagine getting into thermal trouble even using a bridged qsc3402 on each box.
I just plain don't get to play that loud that long for home use.
I did get ginned up to try W Parham's cooling plug idea for the lab 12 drivers once. So I put temp probes on the drivers to see if it was really worth the effort....I'd be in jail before I needed cooling !!
If you go the FLH route 45x45x22.5 handles really easy despite it's size.
And i noticed some of the guys talking about the need to couple boxes to smooth out ripple (which is well known to be the case with the labsubs.)
Here's a link to some simple meas I took of 1, 2, and 4 boxes. (2 lab, 40 hz, should have been 94.2 not 64.2)
Pairing true sub with TurboSound 718
Best, mark
Now we're getting somwhere, I agree with almost your entire post too. The last paragraph I disagree with and I'll tell you why, but first things first. I eliminated the entire first section of the quote because I agree with all that stuff.
Yes, if you run the sub with no filters at all this is true. For graphical representation of this sentence here's the graph. That's shown with 165 V and no filters applied. Technically you can't actually run the sub like this though so this graph is kind of useless, without filters excursion is right around 43 mm, which is well past xlim.
This is actually the reason I said you must have forgotten about the filters when you said 8000 watts at 165 V. Once the filters are applied, as you can see in my Akabak sim, the highest peak is 3800 watts. But without filters your quote here is absolutely true. Impossible to achieve without mechanically destroying the driver, but true nonetheless.
Agreed, you need an amp with a bare minimum of 165 V rails to achieve the last graph.
And this is where we continue to disagree. To paraphrase this (and I hope this is fair) -
From a manufacturer's perspective we can't rate this as capable of handling more than 165 V because some idiot is going to screw up the filters and/or apply too much power and fry the driver.
So a lot of your posts make a lot more sense to me now. I've been discussing the theoretical limits of the design, you've been discussing what you feel is an appropriate rating based on potential misuse. That's a HUGE difference in philosophy. The reason I disagree with this so strongly is because on this forum we should know better. In fact, if the user is a complete idiot and can't figure out how to set the hpf properly excursion is going to be through the roof with 165 V, there's no way to specify a safe rating for an idiot so trying to do so is futile. Manufacturers have to do what they can to try to keep the product safe to reduce warranty claims that they will likely have reject because of misuse but that has nothing to do with discussing max theoretical potential on an audio forum where users are supposed to be a bit smarter than the average drunk idiot working a mixer in a club. Now that I understand why you feel the limit should be 165 V amps I understand why you think this (there's always potential for misuse and mistakes), but the driver can handle way more than that in this cab with filters applied - all my driver power graphs show it's no problem at all because at 165 V and with the necessary filters in place the driver sees way less power on average than Othorn.
The fact that I've been referring to voltage level as the number I input into the sims and you've been referring to it as the amount of actual power that gets through to the driver regardless of filters has also been creating quite a problem. These are two massively different concepts, and since I feel the filters are absolutely necessary for proper operation of the cab I show the results WITH filters in place and refer to voltage as the number I input into the sim. Neither of us is wrong to specify the things in the way we have, but we clearly haven't been talking about the same thing. I've been trying to point this out over the last few posts.
As I showed with my Akabak graphs, the flh at 165 V WITH filters applied consumes WAY less average power than Othorn at 120 V. Which brings me back to my previous point.
IF the system is set up right and the flh is consuming way less average power than Othorn, I think it's fair to add more power to see what the flh is capable of theoretically. Which brings me back to the excursion limited Akabak sim with 250 V input with filters applied (which doesn't actually equate to anything remotely close to 250 V at the driver terminals due to the filters).
Like I mentioned a couple of times, I think this is too much power, it's hitting almost 6500 watts at 30 hz. This would be fine with very dynamic, high crest factor music with not much content below 45 hz, but with anything else this is too much power. I don't think limiting the amp voltage rails to 165 V is enough power either though (and hardly fair since on average it's way less actual power than the Othorn was getting), so that's why I showed this theoretical max potential.
(And while this might be too much power below 45 hz the info is still useful, as it shows that an extra few db is available at higher frequencies if it is needed and you have an amp with enough voltage to push it that far - even with an amp with 250 V rails it's still maxing out at around only 3000 watts above 45 hz, which is still less than Othorn in the same frequency range, so thermal issues above 45 hz are still no problem even with massive voltage amplifiers due to the filters reducing the amount of power the driver actually sees.)
Response, excursion and power graphs shown with 250 V sim input and filters applied (driver never sees anything remotely close to 250 V due to filters).
Yes, if you run the sub with no filters at all this is true. For graphical representation of this sentence here's the graph. That's shown with 165 V and no filters applied. Technically you can't actually run the sub like this though so this graph is kind of useless, without filters excursion is right around 43 mm, which is well past xlim.
This is actually the reason I said you must have forgotten about the filters when you said 8000 watts at 165 V. Once the filters are applied, as you can see in my Akabak sim, the highest peak is 3800 watts. But without filters your quote here is absolutely true. Impossible to achieve without mechanically destroying the driver, but true nonetheless.
An externally hosted image should be here but it was not working when we last tested it.
Agreed, you need an amp with a bare minimum of 165 V rails to achieve the last graph.
And this is where we continue to disagree. To paraphrase this (and I hope this is fair) -
From a manufacturer's perspective we can't rate this as capable of handling more than 165 V because some idiot is going to screw up the filters and/or apply too much power and fry the driver.
So a lot of your posts make a lot more sense to me now. I've been discussing the theoretical limits of the design, you've been discussing what you feel is an appropriate rating based on potential misuse. That's a HUGE difference in philosophy. The reason I disagree with this so strongly is because on this forum we should know better. In fact, if the user is a complete idiot and can't figure out how to set the hpf properly excursion is going to be through the roof with 165 V, there's no way to specify a safe rating for an idiot so trying to do so is futile. Manufacturers have to do what they can to try to keep the product safe to reduce warranty claims that they will likely have reject because of misuse but that has nothing to do with discussing max theoretical potential on an audio forum where users are supposed to be a bit smarter than the average drunk idiot working a mixer in a club. Now that I understand why you feel the limit should be 165 V amps I understand why you think this (there's always potential for misuse and mistakes), but the driver can handle way more than that in this cab with filters applied - all my driver power graphs show it's no problem at all because at 165 V and with the necessary filters in place the driver sees way less power on average than Othorn.
The fact that I've been referring to voltage level as the number I input into the sims and you've been referring to it as the amount of actual power that gets through to the driver regardless of filters has also been creating quite a problem. These are two massively different concepts, and since I feel the filters are absolutely necessary for proper operation of the cab I show the results WITH filters in place and refer to voltage as the number I input into the sim. Neither of us is wrong to specify the things in the way we have, but we clearly haven't been talking about the same thing. I've been trying to point this out over the last few posts.
As I showed with my Akabak graphs, the flh at 165 V WITH filters applied consumes WAY less average power than Othorn at 120 V. Which brings me back to my previous point.
IF the system is set up right and the flh is consuming way less average power than Othorn, I think it's fair to add more power to see what the flh is capable of theoretically. Which brings me back to the excursion limited Akabak sim with 250 V input with filters applied (which doesn't actually equate to anything remotely close to 250 V at the driver terminals due to the filters).
Like I mentioned a couple of times, I think this is too much power, it's hitting almost 6500 watts at 30 hz. This would be fine with very dynamic, high crest factor music with not much content below 45 hz, but with anything else this is too much power. I don't think limiting the amp voltage rails to 165 V is enough power either though (and hardly fair since on average it's way less actual power than the Othorn was getting), so that's why I showed this theoretical max potential.
(And while this might be too much power below 45 hz the info is still useful, as it shows that an extra few db is available at higher frequencies if it is needed and you have an amp with enough voltage to push it that far - even with an amp with 250 V rails it's still maxing out at around only 3000 watts above 45 hz, which is still less than Othorn in the same frequency range, so thermal issues above 45 hz are still no problem even with massive voltage amplifiers due to the filters reducing the amount of power the driver actually sees.)
Response, excursion and power graphs shown with 250 V sim input and filters applied (driver never sees anything remotely close to 250 V due to filters).
An externally hosted image should be here but it was not working when we last tested it.
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If I do that then I will lose some 35-50hz performance. Either shrinking of chamber or increasing S2. If decresing by making S2 a smaller number then we increase the compression. I thought we were staying at 560 to be safe. If pushed to 400 then decrease chamber size we could have very similar response still but now at 4+ compression.
Thanks for the link. I still feel that when you couple the subwoofers together like "V-plating," you do gain extension. But that I feel is because your adding to horn length. But by themselves more isnt going to add extension.
But ya I feel 45 x 45 can be made to move around just fine. AND thermal issues are more of a curiosity really. I wont be using MAX voltage ever to my subs. I know the amps I will be purchasing for the future wont be capable of that. Even if I was able to afford the bigger amp I am interested in it only has 155v rail capacity. AND more than likely I would use it in stereo.
Sure it is, just not as much as most people think. You'll get 2 or 3 hz more low end extension by stacking flhs. You'll also get a bit more forward directivity if the frontal area gets big enough, Weltersys calls it the "barn door" effect.
I've seen a lot of people that think stacking flhs is going to add an octave of low end extension. That's just silly. You'll get a bit but not nearly that much. It's all measurable.
You are an avs member, no? Have you checked out the Sanway clone amp? If it puts out 14000 watts at 4 ohms as advertised, that's about 237 V rails. And it's reportedly $1000 US including shipping, taxes, and everything else. Probably cheaper than the amp you are looking at and a boatload more power.
Some people like to complain that it can't put out 14000 watts rms continually, but that hardly matters unless you want to play sine waves at max output all day. It's a really powerful amp and although I hate subjective reviews people that have used both types have mentioned that it beats 4 Behringer EP4000 amps.
It's probably smart to not push things to the absolute limits, but at these prices it shouldn't be because you don't have equipment that couldn't do it if you wanted to. This amp is cheaper than the sub once you factor in driver costs, shipping, taxes wood, construction materials.
The sub will still be cheaper because the horrible exchange rate from AUD to USD. Anyways I know all about the clone amp and while I think it would be a great value I have not fully convinced myself to buy one. I also wont be buying any Behringer products.
I have more confidence in Johnson to aid in repairs so its a possibility. BUT I dont mind paying more for something like a lesser powerful amps that is reliable from QSC. BUT I am not worried about amps for now.
Also I was not a big fan of the LG amps wall socket demands. Some of the amps out there are much easier demand on the power points. I want to buy amps that have better PS so when I go out and become portable with only a generator it will be an easier load and there for have more options for generator options.
So its mainly a matter of buying one and having something very versatile verse less versatile. Best thing for me would be to have a clone amp at home and other amps for portability.
BUT I am already looking at getting an amp from someone that heavily modified a clone amp so that it is very stable and reliable. So in the end I will have a great value amp that puts out any voltage I would want to use. Will see how it does on a generator but thats way down the road.
For me I am looking at:
QSC PLD 4.2 x2
Crest Pro 7200
Clone-like amp.
Yamaha P2500S
But thats again down the road. WAY down the road. It takes me quite a while to save up money. This is DIY because I have four children, stay at home father and just get by. So things come very slow. BUT I can see I will get there soon enough.
I have more confidence in Johnson to aid in repairs so its a possibility. BUT I dont mind paying more for something like a lesser powerful amps that is reliable from QSC. BUT I am not worried about amps for now.
Also I was not a big fan of the LG amps wall socket demands. Some of the amps out there are much easier demand on the power points. I want to buy amps that have better PS so when I go out and become portable with only a generator it will be an easier load and there for have more options for generator options.
So its mainly a matter of buying one and having something very versatile verse less versatile. Best thing for me would be to have a clone amp at home and other amps for portability.
BUT I am already looking at getting an amp from someone that heavily modified a clone amp so that it is very stable and reliable. So in the end I will have a great value amp that puts out any voltage I would want to use. Will see how it does on a generator but thats way down the road.
For me I am looking at:
QSC PLD 4.2 x2
Crest Pro 7200
Clone-like amp.
Yamaha P2500S
But thats again down the road. WAY down the road. It takes me quite a while to save up money. This is DIY because I have four children, stay at home father and just get by. So things come very slow. BUT I can see I will get there soon enough.
Agreed. That's just how experience has taught me to look at things. I wouldn't necessarily say that you have to be a complete moron. I mean lots of guys I know wring every last dB out of their systems and these guys should know better really (not how I like to run things at all) but it happens often. Dave the OP isn't one of those guys I'd hope but sometimes you have a few extra beers and you are showing off the system to some friends and next you know the cab is getting the full 165v or close and you make the sweet smell of vc adhesives.
At least now we are on the same page. Too bad it took about 15000 words. Communication skills are not my strong suit.
I understand what you are saying. It's just my opinion that if a damaging amount of energy is available in the system amplifier there is always a potential that it will be applied to the driver at some point either through accident, misuse, or being unaware of how hard the system is actually being driven. There is always the potential for a "rogue" signal to find its way in as well. I definitely do not envy manufacturers because of this. It's similar to the testing I do at DB. I get guys who look at the passive system tests and do not understand that some of the output figures aren't very realistic for them to achieve. They don't realize the dangers of having 300v worth of amplifier on tap and that while you may be able to VERY briefly apply that much voltage to a sub up near 80Hz if you allow the amplifier to do the same down near 30Hz you grenade your driver instantly.
Anyway now that we are on the same page we can get back to regularly scheduled programming of helping Dave design himself a FLH.
So Dave you are looking at a 45x45x? form factor similar to a LabSub correct? The GH was a little over 600L (I think 630ish) and that was 45x45x24. You'll have to get a little creative to get a 21 inside a 22.5" wide cab as the frames are typically 21.5" or so. 24" width gives a bit of room for error. Pretty much why my cabs were 24" width.
At this point the simulation part is easy. The problem comes when you try to fold up what you sim'd into a cabinet you can live with. Sometimes you find that the length ends up a little longer or shorter than you were trying to go or you find that the fold won't fit with the amount of area you had entered at your major areas of the horn or you run into logistical problems like accessing the driver or simple things like where to put the terminals. If you allow the horn to dictate the cab it is a bit easier than if you start with a dimensioned cab and put the horn into that space. In that case you'll find that in most cases your cabinet design ends up veering off a bit from the ideal simulation you wanted to match, but at the end of the day a little variation from the sim isn't a deal killer and you probably would never notice.
Also how is your second hand amplifier market over there? We sometimes see Crest 9200's for around $1250 and QSC PL380's for $1400. Other beefy amps you can find used in that range are Crest 9001's (My back!) and QSC PL6.0II's. I'd personally stay away from the PL9.0 and 6.0 PFC the power supplies have a habit of blowing up. I can understand not wanting to do the Sanway. It's not my deal either, but a lot of guys do run them.
At this point the simulation part is easy. The problem comes when you try to fold up what you sim'd into a cabinet you can live with. Sometimes you find that the length ends up a little longer or shorter than you were trying to go or you find that the fold won't fit with the amount of area you had entered at your major areas of the horn or you run into logistical problems like accessing the driver or simple things like where to put the terminals. If you allow the horn to dictate the cab it is a bit easier than if you start with a dimensioned cab and put the horn into that space. In that case you'll find that in most cases your cabinet design ends up veering off a bit from the ideal simulation you wanted to match, but at the end of the day a little variation from the sim isn't a deal killer and you probably would never notice.
Also how is your second hand amplifier market over there? We sometimes see Crest 9200's for around $1250 and QSC PL380's for $1400. Other beefy amps you can find used in that range are Crest 9001's (My back!) and QSC PL6.0II's. I'd personally stay away from the PL9.0 and 6.0 PFC the power supplies have a habit of blowing up. I can understand not wanting to do the Sanway. It's not my deal either, but a lot of guys do run them.
For my subs amp I will just be using my Crest 7200 in stereo. Then down the road I will be looking at a 4.5 from QSC. PLD or cinema style. 155v rails in stereo wont be enough to max the system out but enough to have fun.
WAS also looking at second hand from Europe. Most are 230v already and lots of 9001's. Havent found many QSC but they are hard to convert to 240vac. While the Crest 9200 is a simple removal of jumper plug. Dont know enough about the 9001 amp to be certain of anything. Had one once when I had an older EAW PA setup in Indiana and loved the 9001. BUT most say it is a great amp but the PL380's are better at delivering wattage and not killing the wall.
BUT all that being said 9001's are the best bet for me. Shipping sucks but value used they cant be beaten. PLUS they are every where.
And the Clone like amp will be used mainly at home for my quad 15 setup. That is a Dave Bosso amp and not really much of a clone amp after all his mods. So I would prefer to keep that amp at home.
Just saw the 001 series are Toroidal PS. So no worries about converting but hate to think what shipping will be from Europe.
WAS also looking at second hand from Europe. Most are 230v already and lots of 9001's. Havent found many QSC but they are hard to convert to 240vac. While the Crest 9200 is a simple removal of jumper plug. Dont know enough about the 9001 amp to be certain of anything. Had one once when I had an older EAW PA setup in Indiana and loved the 9001. BUT most say it is a great amp but the PL380's are better at delivering wattage and not killing the wall.
BUT all that being said 9001's are the best bet for me. Shipping sucks but value used they cant be beaten. PLUS they are every where.
And the Clone like amp will be used mainly at home for my quad 15 setup. That is a Dave Bosso amp and not really much of a clone amp after all his mods. So I would prefer to keep that amp at home.
Just saw the 001 series are Toroidal PS. So no worries about converting but hate to think what shipping will be from Europe.
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I don't disagree, people should be careful and maybe not try to push the system to the bleeding edge. For example, although I don't have experience with this driver, every single driver I've ever heard starts to sound pretty bad by the time it hits xmax, so I'm not sure I would ever push this driver as far past xmax as you advocate. Safe? Sure. Sound great? Probably not. So from my perspective most this is moot anyway, but you set the 20 mm standard and I just showed max potential within that criteria.
Regardless of how many words it takes I think it's important to come to agreement when possible. If not for our own sanity, at least for the people who are watching and trying to figure out what the correct answer is. And it turns out we were both right, but discussing very different things at times. And I'm glad it's over but even more happy that we were finally able to come to an understanding on all points. Now I can say a few words about folding.
So. Folding is a big topic. I don't have time to cover anything more than the absolute bare minimum so I'll keep this brief and post a lot of links because this has already all been discussed before.
First thing you need to decide is whether truck pack dimensions are important to you. Truck pack dimensions are always multiples of 22.5 inches. That's why Labhorn is exactly 45 x 45 x 22.5. It doesn't lend itself to efficient use of sheet wood products but a lot of people only want cabs with truck pack dimensions.
I understand that you probably don't care for your personal use, but consider the fact that other people might want to build your design and might want to build a lot of them and might want to pack them in a truck. It's possible that your design could become more popular if you use truck pack dimensions. If you do a good job and also make it pack space friendly there's a strong possibility that this could become a popular pro sound sub used in multiples. The size, tuning and driver selection have a big potential to be a popular design in pro circles.
Next thing I would seriously consider is size and weight. To keep both these things down to a minimum you don't want a symmetrical layout like Keele's that was shown earlier. They look fantastic but take more wood and more wood takes more space and adds more weight for essentially the same performance.
Also on the size and weight topic, I'd keep it to Labhorn dimensions or smaller. That's going to be about 628 liters net in your sim. That's about the limit that one person can comfortably move up and down a ramp on a fridge cart. Of course this is completely up to you, and you could even use 1/2 inch plywood like Bill Fitz does if it's extremely well braced, but this is a compromise and it's not something I would do. But it would save a huge amount of weight and space if you did.
Another thing you probably should consider is that keeping the last bend as far back from the mouth as possible will save the maximum amount of space (dead space) in the last bend. Sine's layout puts the last bend as far back as possible, and for that reason the amount of dead space in that last corner is very small. If he had laid it out the other way, with the last bend very close to the mouth, that last bend would have a huge dead space in the last corner. This isn't an issue when the cab is square, but if it's rectangular it's best to lay it out to keep that last bend as far back from the mouth as possible. If this isn't clear I can draw pics.
I've got a lot more to say so I probably should break this up into several posts.
First thing you need to decide is whether truck pack dimensions are important to you. Truck pack dimensions are always multiples of 22.5 inches. That's why Labhorn is exactly 45 x 45 x 22.5. It doesn't lend itself to efficient use of sheet wood products but a lot of people only want cabs with truck pack dimensions.
I understand that you probably don't care for your personal use, but consider the fact that other people might want to build your design and might want to build a lot of them and might want to pack them in a truck. It's possible that your design could become more popular if you use truck pack dimensions. If you do a good job and also make it pack space friendly there's a strong possibility that this could become a popular pro sound sub used in multiples. The size, tuning and driver selection have a big potential to be a popular design in pro circles.
Next thing I would seriously consider is size and weight. To keep both these things down to a minimum you don't want a symmetrical layout like Keele's that was shown earlier. They look fantastic but take more wood and more wood takes more space and adds more weight for essentially the same performance.
Also on the size and weight topic, I'd keep it to Labhorn dimensions or smaller. That's going to be about 628 liters net in your sim. That's about the limit that one person can comfortably move up and down a ramp on a fridge cart. Of course this is completely up to you, and you could even use 1/2 inch plywood like Bill Fitz does if it's extremely well braced, but this is a compromise and it's not something I would do. But it would save a huge amount of weight and space if you did.
Another thing you probably should consider is that keeping the last bend as far back from the mouth as possible will save the maximum amount of space (dead space) in the last bend. Sine's layout puts the last bend as far back as possible, and for that reason the amount of dead space in that last corner is very small. If he had laid it out the other way, with the last bend very close to the mouth, that last bend would have a huge dead space in the last corner. This isn't an issue when the cab is square, but if it's rectangular it's best to lay it out to keep that last bend as far back from the mouth as possible. If this isn't clear I can draw pics.
I've got a lot more to say so I probably should break this up into several posts.
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Next thing you want to consider is the folding method. A lot of people use a lot of different things but I think centerline method and advanced centerline method are the most popular. Advanced centerline is the most accurate but realistically it's only going to make a few cm difference to the horn length. When I reverse engineered Lilmike's F20 I looked at the difference between the two methods, and the difference amounted to about 20 cm between the two methods. Advanced centerline was more accurate but when the sims are overlaid the difference is not quite 1 hz. Advanced centerline is more work but very slightly more accurate.
If you are not familiar with it, here's a pic, advanced centerline is in the middle, centerline is far left. This is soho54's pic from here - http://www.diyaudio.com/forums/subwoofers/171747-spreadsheet-folded-horn-layouts-2.html#post2270926
Next thing you should probably consider is how most folds get messed up so you know how to avoid it in your own fold.
Soho54 illustrates the importance of placing your segment markers in the right spot when folding in this series of pictures that he posted here - http://www.diyaudio.com/forums/subwoofers/175658-tham15-compact-15-tapped-horn-21.html#post2451737
He's talking about reverse engineering in this post, but the same thing applies the other way. This is also the same issue when folding.
When placed in the wrong spot the simulation simply doesn't match the horn you folding. In this case he colored the volume of error in blue. Most people aren't careful with this, they just place the segment markers arbitrarily in the sim and aren't careful to make sure the flare rate change points match their fold as they lay it out and draw it up into plans.
This last one is what happens when you opt for a three section horn, instead of the four section simulation.
All credit to soho54 for those pics too, click the link and read his post, he explains all this very well.
Now ironically, if you use soho54's Sketchup Tutorial for Horn Folding, that method will guarantee with almost 100 percent certainty that you will mess up the location of the segment markers and introduce errors like those shown in the above pics unless the entire flare contains no flare rate changes at all. It will also introduce other types of errors as well unless you are really careful and understand very well what you are doing in the first place, in which case you don't really need to fold in this manner with Sketchup. You can fold like this if you want but you really need to know what you are doing if you want to end up with anything resembling an accurate fold that matches the sim you started with.
If you are not familiar with it, here's a pic, advanced centerline is in the middle, centerline is far left. This is soho54's pic from here - http://www.diyaudio.com/forums/subwoofers/171747-spreadsheet-folded-horn-layouts-2.html#post2270926
Next thing you should probably consider is how most folds get messed up so you know how to avoid it in your own fold.
Soho54 illustrates the importance of placing your segment markers in the right spot when folding in this series of pictures that he posted here - http://www.diyaudio.com/forums/subwoofers/175658-tham15-compact-15-tapped-horn-21.html#post2451737
He's talking about reverse engineering in this post, but the same thing applies the other way. This is also the same issue when folding.
When placed in the wrong spot the simulation simply doesn't match the horn you folding. In this case he colored the volume of error in blue. Most people aren't careful with this, they just place the segment markers arbitrarily in the sim and aren't careful to make sure the flare rate change points match their fold as they lay it out and draw it up into plans.
This last one is what happens when you opt for a three section horn, instead of the four section simulation.
All credit to soho54 for those pics too, click the link and read his post, he explains all this very well.
Now ironically, if you use soho54's Sketchup Tutorial for Horn Folding, that method will guarantee with almost 100 percent certainty that you will mess up the location of the segment markers and introduce errors like those shown in the above pics unless the entire flare contains no flare rate changes at all. It will also introduce other types of errors as well unless you are really careful and understand very well what you are doing in the first place, in which case you don't really need to fold in this manner with Sketchup. You can fold like this if you want but you really need to know what you are doing if you want to end up with anything resembling an accurate fold that matches the sim you started with.
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