I have always built sealed subs; several reasons, but anyway, I have been looking into BP-4 alignments to reduce the mid base distortion mostly, and because I never did one. Anyway, I have a Dayton RS265 HD and a Dayton Titanic 10. Both good drivers for their size, reasonably low distortion, and work well sealed. Small, but I listen to music not insane loud special effects. They seem to model pretty well, but I do not know what a BP driver should be optimized for. Both have low EBP. Ports come out very long, but do-able. Do I want a low or high Qts for example?
So, wondering if there are suggestions for alternate drivers that are known to work well in BP-4. I need to pass 25 to 80 Hz. The Titanic comes out pretty good at about -3 dB within less than a dB of ripple. Excursion is within reason as long as I toss in a 20 Hz first order HP.
I looked into PRs as I have not dealt with them before. I see some advantages, but would need probably at least a 12, if not a pair of 10's. Costly. 4 inch port is coming out as 9 m/s but 42 inches long. I had a 3 on the Titanic years ago and it was horribly chuffing. I think it calculated at 17. So much for 1/10 Mach theory.
So, wondering if there are suggestions for alternate drivers that are known to work well in BP-4. I need to pass 25 to 80 Hz. The Titanic comes out pretty good at about -3 dB within less than a dB of ripple. Excursion is within reason as long as I toss in a 20 Hz first order HP.
I looked into PRs as I have not dealt with them before. I see some advantages, but would need probably at least a 12, if not a pair of 10's. Costly. 4 inch port is coming out as 9 m/s but 42 inches long. I had a 3 on the Titanic years ago and it was horribly chuffing. I think it calculated at 17. So much for 1/10 Mach theory.
Same as a BR, i.e. the larger the Vas, the shorter the vent required to get a low enough vent mach and a driver optimized for a max flat alignment [~0.403 Qts'] is required for a max flat BP4. Ditto as you move [Qts'] up/down and the higher the power handling, the larger/longer the vent, so a 2x larger [Sd] PR is desirable.
GM
GM
Sometime, closed back dual front bandpass (adding another front chamber to a 4th order) allow better bandwith, and allow to use 2 different lenght shorter vent instead of one longer, and so less resonnance. But with 3 spike on impedance chart, it's now a 6th order bandpass, with faster low pass roll off. It allow to benefit of limitating excursion feature of closed back enclosure as 4th order enclosure, and so to use less step overexcursion high pass. As with 4th, you would prefer to put driver magnet side on front chamber side temperature wise. It's easy to sim with hornresp chosing Type B bandpass BPB enclosure. With 2 front chamber, every out of band noise (mechanical noise from driver + most harmonics) are filtered. About port chuffing, here a excellent reference tool for flaring in and out port radius : Flare-it - Free Speaker Design Software
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@tvrgeek What is a BP-4 driver? What does EPB mean? “...4 inch port is coming out as 9 m/s” What does “9 m/s” mean?
@GM Please expand on each below. In particular what I have in bold text.
a. “...driver optimized for a max flat alignment [~0.403 Qts'] is required for a max flat BP4.”
b. “Ditto as you move [Qts'] up/down and the higher the power handling*, the larger/longer the vent, so a 2x larger [Sd] PR is desirable.”
*I’m unclear what this means or how it would affect a vented alignment
@papasteack what is a “band pass BPB enclosure.” I know what band pass means though not interested in that alignment.
So that you know, I’ve done DIY going WAY back to the early 80s, before we had modeling software. We had to plug the TS* parameters into charts and do a little algebra. I’m very familiar w/the terms* and pretty familiar w/how, for example, QTS affects F3 or closure sizes if VAS & Rs are the same for two drivers.
Eager to expand my knowledge as I’m want to, one day, build several subs for my HT. I think I’ve selected the right driver and alignment, but until I’m ready* to drop the coin, I will study other possibilities.
*busy w/Honey doos
Many thanks for your thoughts and patience. Tony
@GM Please expand on each below. In particular what I have in bold text.
a. “...driver optimized for a max flat alignment [~0.403 Qts'] is required for a max flat BP4.”
b. “Ditto as you move [Qts'] up/down and the higher the power handling*, the larger/longer the vent, so a 2x larger [Sd] PR is desirable.”
*I’m unclear what this means or how it would affect a vented alignment
@papasteack what is a “band pass BPB enclosure.” I know what band pass means though not interested in that alignment.
So that you know, I’ve done DIY going WAY back to the early 80s, before we had modeling software. We had to plug the TS* parameters into charts and do a little algebra. I’m very familiar w/the terms* and pretty familiar w/how, for example, QTS affects F3 or closure sizes if VAS & Rs are the same for two drivers.
Eager to expand my knowledge as I’m want to, one day, build several subs for my HT. I think I’ve selected the right driver and alignment, but until I’m ready* to drop the coin, I will study other possibilities.
*busy w/Honey doos
Many thanks for your thoughts and patience. Tony
=> BP-4 is a enclosure arrangement. Seach for 4th order bandpass box. It's putting a driver in a closed box aka back chamber, adding another volume in front of the driver, but this time opened, with a port.
=> 9m/s is the velocity of air through output port at his calculated usable maximum for the simulated enclosure. We got some guideline to use this information to avoid turbulences of air at high volume/low frequencies, and it helps to choose the good compromise of size of the port. Big port : "less chuffing"/"less compression", but longer, so "resonnant".
=> a. About alignement; it's a mathematical measure of the shape of the response, but linked to the phase response of the driver, giving information about the resonnant nature of the system at his lower corner frequency. GM know good receipt ^^
=> b. Same as before, it's all about receipt to make things works the more ideal.
=> BPB : There's nothing official. You can put in front of a driver in as many successive chambers connected with port as you want. But result will be hard to predict. Hornresp allow to simulate lot of classical enclosure type, and some type of alignement that don't really have a name. BPB, is bandpass B, after bandpass A, and before bandpass C. With classical naming, BPB should be named as closed back enclosure with two serie bandpass front chambers. I wanted to name it CBDBPFC, (closed back dual bandpass front chamber) but it didn't seem to get interest ^^ I like bandpass alignement for home only for their filtering. But at higher volume than home, bandpass suffers from compression and chuffing due to the use of port. For higher volume tapped horn (that can be tune either to smooth response low order, or higher order for efficiency) offers more interesting set of characteristics and compromises.
=> 9m/s is the velocity of air through output port at his calculated usable maximum for the simulated enclosure. We got some guideline to use this information to avoid turbulences of air at high volume/low frequencies, and it helps to choose the good compromise of size of the port. Big port : "less chuffing"/"less compression", but longer, so "resonnant".
=> a. About alignement; it's a mathematical measure of the shape of the response, but linked to the phase response of the driver, giving information about the resonnant nature of the system at his lower corner frequency. GM know good receipt ^^
=> b. Same as before, it's all about receipt to make things works the more ideal.
=> BPB : There's nothing official. You can put in front of a driver in as many successive chambers connected with port as you want. But result will be hard to predict. Hornresp allow to simulate lot of classical enclosure type, and some type of alignement that don't really have a name. BPB, is bandpass B, after bandpass A, and before bandpass C. With classical naming, BPB should be named as closed back enclosure with two serie bandpass front chambers. I wanted to name it CBDBPFC, (closed back dual bandpass front chamber) but it didn't seem to get interest ^^ I like bandpass alignement for home only for their filtering. But at higher volume than home, bandpass suffers from compression and chuffing due to the use of port. For higher volume tapped horn (that can be tune either to smooth response low order, or higher order for efficiency) offers more interesting set of characteristics and compromises.
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As above. EPB, Energy Product Bandwidth, is a calculated factor which suggests if a driver is most suited for a ported or sealed enclosure. The lower, the more likely it is suitable for sealed.
As I had not played with the BP alignment much, I was discouraged with all three of my subs. But spending a bunch more time to get a better feel for the BP shape and the relation between the two chambers, turns out they look to be quite suitable. Just a long port, but I have solutions for that. Curious, small changes in alignment can halve the port length for 2 Hz!
I have a "good" solution worked out for my 10 inch Dayton Titanic. I will prototype it as soon as I finish the re-cabinet of my mains. As this is a small room HT and I do not care for sub-sonic effects that can be heard three blocks away, it looks like a slick choice. ( It is in a critical Q sealed cabinet right now) Adding in expected room gain, pretty much 25 to 80Hz losing only a dB in simulation. Broader will drop as much as 3 to 5 db and I run out of power real fast to get 5 more Hz out of it.
Looking at cone excursion, I still need to add a 20 or 25Hz first order electrical filter to the amp front end. Going with a port as a pair of 10 or 12 PRs is a bit expensive. I'm keeping that idea in the background though as it seems like it could be the optimum configuration, price no object.
I am going to build it is two pieces. First, to be able to lift it into position and second, all my "solutions" have the same sealed size. Sensitive to the front chamber mostly. I might make a couple to compare.
Yea, for a big honking stadium or even a club, port noise would be excessive and building 15's with multiple 15 PRs would be getting out of hand. One size fits... one.
Driving it with an old O-Audio BASH 300W amp. I am hoping the actual in use distortion to be in the single digits. I stay below 80% x-max and more than 6 dB overhead @ 110 dB 1M. Or so the computer says.
As I had not played with the BP alignment much, I was discouraged with all three of my subs. But spending a bunch more time to get a better feel for the BP shape and the relation between the two chambers, turns out they look to be quite suitable. Just a long port, but I have solutions for that. Curious, small changes in alignment can halve the port length for 2 Hz!
I have a "good" solution worked out for my 10 inch Dayton Titanic. I will prototype it as soon as I finish the re-cabinet of my mains. As this is a small room HT and I do not care for sub-sonic effects that can be heard three blocks away, it looks like a slick choice. ( It is in a critical Q sealed cabinet right now) Adding in expected room gain, pretty much 25 to 80Hz losing only a dB in simulation. Broader will drop as much as 3 to 5 db and I run out of power real fast to get 5 more Hz out of it.
Looking at cone excursion, I still need to add a 20 or 25Hz first order electrical filter to the amp front end. Going with a port as a pair of 10 or 12 PRs is a bit expensive. I'm keeping that idea in the background though as it seems like it could be the optimum configuration, price no object.
I am going to build it is two pieces. First, to be able to lift it into position and second, all my "solutions" have the same sealed size. Sensitive to the front chamber mostly. I might make a couple to compare.
Yea, for a big honking stadium or even a club, port noise would be excessive and building 15's with multiple 15 PRs would be getting out of hand. One size fits... one.
Driving it with an old O-Audio BASH 300W amp. I am hoping the actual in use distortion to be in the single digits. I stay below 80% x-max and more than 6 dB overhead @ 110 dB 1M. Or so the computer says.
It’s EMF. Effective Motor Force, But now we are all confused, 
. I just wanna make whatever Papasteak has a ‘receipt’ for? cause the more confusing the better! It started with MLTL, but now that’s all explained. And it’s a treat!! . let’s keep it going? But no acronyms maybe? all together?
The ultimax bp sounds good too wolf??
. I just wanna make whatever Papasteak has a ‘receipt’ for? cause the more confusing the better! It started with MLTL, but now that’s all explained. And it’s a treat!! . let’s keep it going? But no acronyms maybe? all together?The ultimax bp sounds good too wolf??
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I think I sim this in another way with similar attributes? outside of taped horn, but very little ‘path’ and offset driver/ offset stub.... maybe?
My dyslexia. So much fun. I used to work in a building where every room had a multi-digit code. Rang the doorbells a lot.
Speaker design is an engineering discipline. Engineers love acronyms. For one thing, we are lazy writers and frequently can't spell. One of the reasons I suggest an "obsolete approach", as I have been accused, is if you read something like Testing Loudspeakers by Joe D'Appolito, all the terms get defined. More important, defined mathematically in relation. I do not suggest using the old manual method for measuring drivers, I love my PC based lazy tools too, but if you understand the physics, then it will make more sense.
Best references I can find is a PR may have twice the excursion as the driven element, so it should be a minimum of twice the SD. One 12 comes up short at around 140%. I have not built one, so I am just going by design guidelines I have found. Maybe I am fooling myself as it really means the main driver is running half what it would if it were facing outside. ( also good for linearity) Anyway, going to prototype a 4 inch duct and see if it has issues. If it does, then a PR would be next.
Speaker design is an engineering discipline. Engineers love acronyms. For one thing, we are lazy writers and frequently can't spell. One of the reasons I suggest an "obsolete approach", as I have been accused, is if you read something like Testing Loudspeakers by Joe D'Appolito, all the terms get defined. More important, defined mathematically in relation. I do not suggest using the old manual method for measuring drivers, I love my PC based lazy tools too, but if you understand the physics, then it will make more sense.
Best references I can find is a PR may have twice the excursion as the driven element, so it should be a minimum of twice the SD. One 12 comes up short at around 140%. I have not built one, so I am just going by design guidelines I have found. Maybe I am fooling myself as it really means the main driver is running half what it would if it were facing outside. ( also good for linearity) Anyway, going to prototype a 4 inch duct and see if it has issues. If it does, then a PR would be next.
Okay, same idea, it
Just became really popular when David made OD closed and Ap exit... a few tries later and it stuck. Like Bp6 In TH might? ones easier for some people and the other for others. I try to use both but more I seperate parts in simmed individuals. kind of helps my pea brain and overlaid is even more of the mind thinking fog is a bit cleared or it’s placebo... lol.
Throw out a sim and I’ll try it?
TVRgeek: I think it might be the slang that’s messing it up more than engineers!? I
there’s a big vented reflex and MLTL and bass reflex... but that’s not even starting. I’m sure you’ve heard every version of a massloaded qw pipe. But 12 of nicknames and acronym if we wanted or more? Tapped versions then add to ur all and suddenly tapered is tapped to damped is dampened? It is hard as a newbie, and I’m no far enough away from the memory of it yet.
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Add that we forgot how to use a dictionary:
Flammable or inflammable? Totally redundant words like "utilize" which has no use that use does not have other than sounding important with three syllables.
I did a dozen or so sims using WinISD. Time to prototype. The only truth is when measured in-situ. About 6 projects in line first. Recapping all my equipment, new HT mains, new power supplies for DAC and crossovers, new crossover and so on. I need to sell all my surplus to pau for new bits. It cascades! Put one project aside while waiting for parts and start another. Wait and start another. At least my done pile is starting to grow!
Flammable or inflammable? Totally redundant words like "utilize" which has no use that use does not have other than sounding important with three syllables.
I did a dozen or so sims using WinISD. Time to prototype. The only truth is when measured in-situ. About 6 projects in line first. Recapping all my equipment, new HT mains, new power supplies for DAC and crossovers, new crossover and so on. I need to sell all my surplus to pau for new bits. It cascades! Put one project aside while waiting for parts and start another. Wait and start another. At least my done pile is starting to grow!
Sorry I missed this...
EMF is something else entirely.
Yes- the Overdrive10 sounds great! I really like this little box...
Wolf
To you it is electro magnetic field .... but in the case of a much more complex use of a transducer where the Ultimax falls in its face it is motor force that must over come EMF to survive. it’s a hard place for a speaker and a can of worms to get deeply into it. I’m almost going backwards in order to find the happy place instead of headache! Too much headache is not fun!
Ultimax 8 is fun, 10 is likely too?
In your TechTalk blog or posts at parr’s express? I think pohotobucket has lost everyone’s stufff and years of it all over the web.. sad. Mines long gone too..
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