I've been looking at the ROAR and other similar designs a bit lately, and wondering whether a compact 8" based version would work. Using the MCM 55-2421 or Dayton dcs205 it seems workable, perhaps...?
Here is a hornresp sim of a scaled down ROAR10 with the MCM 55-2421. Predicted frequency response is...well, a bit peaky! But it seems not drastically different from the ROAR10, and can perhaps be improved upon. It would need to cross at around 150Hz for the intended application.
Diaphragm displacement is predicted to be nicely controlled at pMax (eg 21.91), staying below xmax down to around 40Hz. Only around 70 litres net.
I have some of these drivers lying around, and access to CNC, will be happy to share some measurements and so on if I end up building one or two...
Any thoughts would be welcome, cheers!
Here is a hornresp sim of a scaled down ROAR10 with the MCM 55-2421. Predicted frequency response is...well, a bit peaky! But it seems not drastically different from the ROAR10, and can perhaps be improved upon. It would need to cross at around 150Hz for the intended application.
Diaphragm displacement is predicted to be nicely controlled at pMax (eg 21.91), staying below xmax down to around 40Hz. Only around 70 litres net.
I have some of these drivers lying around, and access to CNC, will be happy to share some measurements and so on if I end up building one or two...
Any thoughts would be welcome, cheers!
Any tips on what to look for in terms of the sims and optimising the design? L45 will have to come down a bit in reality and compression increase a bit to keep the dimensions practical I think...
Carlos,
Increasing the compression ratio to at least 2/1 should not be a problem.
In post #1 you wrote "It would need to cross at around 150Hz for the intended application".
The extremely peaky response in that frequency range looks problematic even if you plan on using parametric equalization.
Increasing the compression ratio to at least 2/1 should not be a problem.
In post #1 you wrote "It would need to cross at around 150Hz for the intended application".
The extremely peaky response in that frequency range looks problematic even if you plan on using parametric equalization.
Thanks very much - yes crossing at 150 is ambitious given the sim. However perhaps the reality is not as bad? I'd like to give one of these a try, the efficiency would be great for battery power and in an 8" size it is reasonably compact and portable.
I'd like to know, how peaky is too peaky in the sim with this type of box? How much compression is good? If excursion is lowered in reality vs sims, is it ok to use a low xmax high BL driver - for eaxmaple, the Beyma 10MI100 (black in image below) sims pretty well in the ROAR 10 but xmax is predicted to be exceeded and it is a mid driver not a bass driver...would be good to have the voice of experience on these matters 🙂
I'd like to know, how peaky is too peaky in the sim with this type of box? How much compression is good? If excursion is lowered in reality vs sims, is it ok to use a low xmax high BL driver - for eaxmaple, the Beyma 10MI100 (black in image below) sims pretty well in the ROAR 10 but xmax is predicted to be exceeded and it is a mid driver not a bass driver...would be good to have the voice of experience on these matters 🙂
Attachments
A low Xmax high BL driver should be fine for battery power.
High compression ratios are fine until the cone folds up ;^) .
Whether something is "too peaky" is subjective, but the chart in #5 looks OK for a steep 150 Hz crossover, as the dip would be more than 1/3 octave above the crossover point.
High compression ratios are fine until the cone folds up ;^) .
Whether something is "too peaky" is subjective, but the chart in #5 looks OK for a steep 150 Hz crossover, as the dip would be more than 1/3 octave above the crossover point.
So I think I'll have a go at an 8" version of the ROAR10. Rescaled using Brian Steele's extremely helpful Boxplan, it looks something like this:
coming up a little large with the extension to the front resonator, 97 litres total, including unfortunately 5.3 litres of wasted space. Not sure if it's worth it or not, but such a simple build and quite interested to see how it sounds. It could be made a bit more compact with a narrower pipe, but you don't regain much space. And low compression feels quite sensible with this low cost driver.
coming up a little large with the extension to the front resonator, 97 litres total, including unfortunately 5.3 litres of wasted space. Not sure if it's worth it or not, but such a simple build and quite interested to see how it sounds. It could be made a bit more compact with a narrower pipe, but you don't regain much space. And low compression feels quite sensible with this low cost driver.
Dual opposed has some advantages. Either way, you’ll enjoy it. They’re ‘ different’ in how they sound/feel a bit. If you get it just right There’s some sharpness or punctuation to the bass? It has a unique ‘feel’ A few larger ones or similar that I’ve built have almost been ‘painful’ if Played it high volumes.
I always have a slight difference, and a little bit of wasted of space on the corners. Put some handles or wheels in those spots?
i like having an exit with one last 90° turn. Not necessary it just completes the model in the software as represented just like the folds can be.
Then you see some Advantages to the dual set up and driver entry point. If everything is spaced correctly you have a nice symmetry or synchronicity so to speak. Like a pendulum swing from the start. Setting up a spacing. 30 cm from the start(s) or 15 cm can be 12 or 24 in The hypothetical circumference of a circle of 360cm. Which is ~30 Hertz represented in three folds . And then approximately 90 Hz in the single fold(x3).
(If you drew a 1/4, 3(1/4) and 5(1/4) sine wave on the side of the cabinet, or the overhead view to see).
I even started building the cabinet so it’s three equal lengths.
I always have a slight difference, and a little bit of wasted of space on the corners. Put some handles or wheels in those spots?
i like having an exit with one last 90° turn. Not necessary it just completes the model in the software as represented just like the folds can be.
Then you see some Advantages to the dual set up and driver entry point. If everything is spaced correctly you have a nice symmetry or synchronicity so to speak. Like a pendulum swing from the start. Setting up a spacing. 30 cm from the start(s) or 15 cm can be 12 or 24 in The hypothetical circumference of a circle of 360cm. Which is ~30 Hertz represented in three folds . And then approximately 90 Hz in the single fold(x3).
(If you drew a 1/4, 3(1/4) and 5(1/4) sine wave on the side of the cabinet, or the overhead view to see).
I even started building the cabinet so it’s three equal lengths.
Attachments
Ah I was looking at dual drivers, nice one! 👍 that is super simple construction and more space efficient...so something like this:
Not 100% sure where to take L45 from on this layout...?
I'll try to build one next week, nice little BBQ sound system bass box...
Not 100% sure where to take L45 from on this layout...?
I'll try to build one next week, nice little BBQ sound system bass box...
Last edited:
which layout is better? Left as suggested by Mr. Weldz seems to have the advantage, in terms of maximising S45 distance to drop the tuning of the front resonator, depending on how you calculate S34 distance of course...
Jeez, you do nice work!!?? What is that, I need to get off my butt and learn how to do a 3-D program so I can show what I’m talking about better than sketching or a napkin🤪
I’m more concerned with the driver position off of a closed wall or endpoint(reflection) then the idiosyncrasies about that turn coming out of the initial pass to the motor side of the driver.
it’s kind of a sensitive area and lots of ways to interpret it. But if you just keep it simple and dumb it down to the basic shape(3 rectangles ) and don’t overthink the area(?) it tends to do more with information regarding the parallel ends of walls and that length then all the extra information people try to throw at it and confuse it?
Seems advanced center line is kind of a waste of info once you’re only dealing with perfect and repetitive segments of the same Length Which will be close too a folding at node/anti-node in the pressure wave (phase) for the void at the top of bandwidth (3 x 1/4 Fb Harmonic).
i’ve even gone so far as to place the second skinny segment below , on each side and then feeding up through the center of the last wide ( and also) shared resonator?
If you keep this arrangement and tune @ ~30 hz using 30/210cm and 30/105cm for L12/23 and L34/45…respectively . Then look and see what happens at 860 hz (and 860+860+860+860…(1720,2580,3440….8600…. 14620…). . Throughout the upper band frequencies through 19780 Hz.
Those frequencies are very ‘special’ in all waveforms in the entire universe or from the perspective of physics on earth in reference to anything about earth or the solar system and beyond). They define our existence and they describe the matrix or the numerical function of the entire cosmos. Not only that but the mathematical versions of them as Constance will go on to represent anything and everything.
If you notice they’re canceled out, or quite a few of them, you’re aligned nicely into the higher orders. if you look at what a couple of those numbers represent in other areas(add 4 for every one above 860) it’ll start to make sense. Its Pretty freaking cool, especially once you realize what they represent and what’s going on and then what must be going on in the subwoofer as a result of the math behind all of it..
Those frequencies are very ‘special’ in all waveforms in the entire universe or from the perspective of physics on earth in reference to anything about earth or the solar system and beyond). They define our existence and they describe the matrix or the numerical function of the entire cosmos. Not only that but the mathematical versions of them as Constance will go on to represent anything and everything.
If you notice they’re canceled out, or quite a few of them, you’re aligned nicely into the higher orders. if you look at what a couple of those numbers represent in other areas(add 4 for every one above 860) it’ll start to make sense. Its Pretty freaking cool, especially once you realize what they represent and what’s going on and then what must be going on in the subwoofer as a result of the math behind all of it..
Attachments
I'm not sure I follow the above exactly. Extending the front resonator has obvious advantages in the hornresp sim, up to the point at which the peak at the bottom of the passband exceeds the central peak. It seems that making the front resonator 0.77 x the length of the initial resonator gives the flattest response in the passband? So like this:
I can't figure out what will go on with the actual length of the front resonator in reality vs hornresp though - Obviously the L12 and L34 lengths cannot be the same with this fold, and the position of the motor side of the driver in the path can't really be right using HR TH model...
Unfortunately the length of the front resonator does become a problem with making the box a practical shape, not to mention getting on the large side for a dual 8" box...
Instead of making the full length I am thinking of doing a 'too short' front resonator and possibly experimenting with extension board, boundary loading, multiple boxes, all of which seem to offer the chance of smoothing out the freqency response after construction.
Open to suggestions though...
I'll probably build the 'short' version of this, dimensions below with HR inputs on left.
The 'long' version, with L45 extended to 94.39cm is on the right...
I have some CNC time available this week so need to finalise the approach pretty soon...any input welcome!
Still not sure quite what you're getting at I'm afraid - is this the deep 860Hz cancellation you are talking about?
I ran out of time last week but might get a chance to cut later this week, still scratching my head over this. Negative 990dB predicted spl in Hornresp is quite interesting though, not seen (or noticed anyway) a cancellation quite like that in any other sims...
I ran out of time last week but might get a chance to cut later this week, still scratching my head over this. Negative 990dB predicted spl in Hornresp is quite interesting though, not seen (or noticed anyway) a cancellation quite like that in any other sims...
oh I see, perfect cancellation due to l12 and l34 being the same...? -990 being HR for infinite?
Yes sir there’s a sequence of them in a row all the way out to 20 K(last is at 19780hz).
(There’s also a ripple in a sequence of other numbers , they don’t cancel out quite as much but remain throughout alongside that which are on a 12/24/48/96/192 fournier transfer version)
But, If you write down / take note of all of those numbers in the 860 sequence (860,1720,2580,3440….) and add 4,8,12,16 digits to each of them in succession you come out with the most important math Constants in all of physics as well as Number of rotations associated with our plants 25920 year Global warming cycle and The sequence it also shares a similar cycle known as nose art in the flood , which runs along side that And another function causes that which is cataclysm of a comet or meteor strike from the same source over and over. That and the precession of the equinox and many cycles in the solar system and functions of physics at the highest level known to mankind.
It’s amazing as well represented along with other details in that simulation and explains so much about our own universe just by numbers and frequencies and also hard and millions of kilometers for the number of seconds in a day or 12 hoursIt’s amazing as well represented along with other details in that simulation and explains so much about our own universe just by numbers and frequencies and also hard and millions of kilometers for the number of seconds in a day 86400, The diameter of the sun 86400 or Jupiter, And its orbital radius as well as the moons radius and diameter10800 and 21600, and the Big Bang 13834, which is also the diameter of the sun in kilometers along with the number seven in pi(6912) Always missing for further they are from the original 860 just like the results that towards La useAlways missing for further they are from the original 860 just like the results in Bodes law. And so much more
Point is and if you look deeper into that the fact that those are absolute and oppression node that’s practically been described as a vacuum means all of the available energy and entire system has been stripped from them and not wasted in out of bed nonsensPoint is and if you look deeper into that the fact that those are absolute and oppression node that’s practically been described as a vacuum means all of the available energy and entire system has been stripped from them and not wasted in out of band nonsense or the typical harmonic mess and hashmarks and garbage seen up there otherwise.
meanwhile the flight response and wide bed with instant resulting alongside the gain and low pass filter effect of your folding Kept simple like it is laid out in the simulation entries will result in whatever version of the best of the best or the ‘perfectly aligned’ creates.
The math or the steps to achieve those numbers in that sequence that are -990 or the math of the entire universe because 860 is actually 864 when the speed of sound is 345.6 m/s and that is the number of seconds in a day and the 360 cm long pipe is 24 Hertz.
Is an alignment of many things all of which come together cumulatively create a result that itself is shown and the 28.8 Hz represented by 300 cm betweenI Driver entries but also look at what every single one of those dimensions will then be inside the pipe and it was frequency and you have everything in between three and 330 as 300 and correspond to the bandwidth and half of that over and over with the acoustical center being at 150.
But that’s not only lining up with centimeters but the 90 cm is 96 Hertz and saloBut that’s not only lining up with centimeters but the 90 cm is 96 Hertz and that is taken all the way back to the 24 and 36 or the 36 on 24 and everything in between flips and flops centimeters or hz in the same way.
That’s the same exact way as seconds due in 24 hours or 12 or 1That’s the same exact way as second to do in 24 hours or 12 or 144 or 288…
Set up a scenario that is exactly like time is and frequency is as they share the same numbers as distances and functions of 300 or 30 in 360…
that will be 7.5 broken down into a quarter wave element of the town so is the speed of light and that is all described thoroughly in the decimal points of 1÷254. Where we see a pattern and again I 3÷2 five for another set of numbers all of which work together to describe 10,20,40,80,160,320…
Same time that is a diameter of a circle that circle has a circumference which is described further down the decimal points is 03963Same time that is a diameter of a circle that circle has a circumference which is described further down the decimal points is 03937, 07874, 15748, 31496…62662…
those numbers represent angles as well as circumference points on a circle in radians.
good looking either I noticed that this is a function of the speed of light broken into this wave i.e. 1/4
A drawing that has 3060 triangle and using that as the reference point through the planetary model as if they were all lined up in a row and location than the long leg of the triangle consecutively growing larger with the orbit of the planets would be 75 and 150 then 225 then 300 all that wood split the earths own orbit as its diameter around the sun.
A drawing that has 3060 triangle and using that as the reference point through the planetary model as if they were all lined up in a row and location than the long leg of the triangle consecutively growing larger with the orbit of the planets would be 75 and 150 then 225 then 300 all that wood split the earths own orbit as its diameter around the sun nevertheless you develop a hexagon or dodecahedron shape around each orbit using those 30 6090 triangle’s developed by those numbers which are 30° off of that speed of light from the sun moving outward.
looking at the centimeters there’s more information that and the divisions of the Savior by odd numbers.
The decimal points carried out to several dozen digits explains everything on the centimeter. Yet how can that be true unless math existed long before we did and even if pi and the size of the sun is changing constantly, how is it relevant to the current state of the universe that we are sharing right now?
because the day was about 21 hours back at the time the dinosaurs went into extinction. What was pie and what was the sun and stayed in physics at that point as a result?
Because while the sun may be going proportionally bigger and bigger and retaining that pine number in the details of its circumference and radius it does have a metric and imperial version of that which are different digits creating an alternative number for pi that is still however the same proportion.
This is all harmonics and odd-numbered intervals that you want to slip into your quarter wave system to get more out of it instead of ruining all of that by folding it randomly we’re sticking drivers at random locations or the closed ends of each of the segments at any random location.
can’t do that you’re eating up perfection that already existed waiting for you to arrive at it by design?
Hope that sort of makes sense it’s a lot to try to type and to do it well Well not overstating it or abbreviating it at the same time. That’s just being confusing. That’s often what happens no matter what fortunately because this is a crazTo look at and to try to perceive and understand without driving home some numbers and calculus and spiral trigo Or differential equations etc.whatever…
But you really can draw these things as circles and in a pattern that represents things that are all of that math already just gotta pick the right sizes in those sizes are in centimeters information already
Last edited:
Imagine these were gears in a planetary gearbox all of which were interconnected because they fit and they drove the system. Even if they come in a different car rates and ratios the end product due to the arrangement has them all as a contribution or tandem articulated and locked in sequence perfectly to drive the ball gear in the sun gear which is left out at this picture all the circles are exactly the size that is specified by the centimeters only thing left is to put the 62992 on top.
