four 4“ to 40 hz. More of the ‘PipeOh‘ idea, but folded up like a boss wave cannon (3:1 precisely) concept, essentially.
I need a B@SE sticker too😝
I need a B@SE sticker too😝
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As per winisd, I get quite the contrary of Horn resp.
@141L with 800w I get an f3 of 35hz with a qtc of 0.66.
@ ~70l (2.8cuft) I get a qtc of 0.797 with an f3 of ~ 35hz (?!) too. Still 800w.
Whatever I seem to be doing, I can’t get lower f3. Didn’t play with filter tho.
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(1) Crawl space? I think that's the best for butt kickers and the like.
(3) You could build a set of narrow/tall/shallow subwoofer cabinets that could fit in between the studs if you wanted at some point. Hang them on the walls. Build one with four, five or six small drivers and see if you like it to build more.
(4) Not necessarily PA only. Acoustic Energy has made a living off using small drivers even in their "large" speaker. Again, do you want musical bass or LFE? If the former, you can must follow (3) above... if the later, just build with an oversized monster cone... Pfft... not my style though.
(6) A mini Pipe Oh... Seven feet tall, 10 inch wide tube.
(7) I got it. My thought on the Mini Pipe Oh, currently, is to adorn it with Hello Kitty stickers for a more "domestic" look.
OK, go build your monster... but if, when, I build my Mini Pipe Oh's, my woofers will be bigger than your subwoofers. 😛
PS- I have a pair of Entec SW-5 "woofers" too. Very fast... used it with the AE-1's and the Maggie 12's. Have not used it with the Maggie 1.7s. I've wondered if I could mate those into the Mini Pipe Oh.... Mini Pipe SW- ( Hawai'i) Five Oh....
🙂
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Look at excursion, down low it can't handle 800 W sealed.
These the specs you're using?
Double checked my math for 141.58 L, so no clue why you're getting 0.66 @ 141 L unless not using the same specs as me.
2.8 ft^3 = ~79.28717 L per this nifty little freeware I've been using since its inception after finding that the DIY audio 'world' had become metric since I had last been an active 'member'. 🙁
Regardless, whether (2) in 141.58 L or (1) in 141.58/2 = 70.79 L = 0.96 Qtc.
As for how accurate the math is, have never done accurate enough measurements nor done any sims to compare with, though others have and TTBOMK no has noted it being off, though from sims it's obvious it can be off a fair amount in some cases and still not be audibly obvious due to room acoustics, etc..
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F3 is a fairly complex math problem for me, but my math's link has an F3 calculator using Qtc, Fc, which are easy math = ~0.96 Qtc, ~39.83 Hz Fc = ~31.92 Hz/F3
..........but F3 (2x power) isn't of much use since we can barely perceive the difference, F6 (4x power) or higher is where we want to start looking for audible differences.
Sorry. With drivers taking a lot of power, the f3 of the "too small" cabinet can simply be ignored. The air inside the box works like a spring, the less air =the shorter= harder the spring gets. So you need more power to move the cone to the same excursion. Also, the cone instantly returns to zero, when the signal is cut. So the heavy cone does not flap around.
If the amp can deliver this power and the voice coil can take you are done. Sure, from an economical standpoint, a larger volume is better and needs less amp power. If size is not limited, a Qtc as low as .50 is fine for active speakers.
In the old times, when amp power was rare and cone excursion small, we build huge horn constructions, which gave high SPL, but did not reach very deep when size and weight had to stay transport able. Usually 35 Hz was the lowest we could get with huge 18" bass bins. Which is what rock music needs.
A 20 Hz horn of these times fills the whole basement.
Today power is cheap and chassis can use it. This has lead to completely different aims in speaker construction like tapped horns. Today's speaker cabinets simply do not work with old PA speakers and amps of the time if PA SPL is needed.
Fast bass is a myth that has been proved to be wrong a thousand times. Still some do not get the message. what they consider to be "slow bass" is resonant bass or not time correct reproduction. There is no slow or fast reproduction of the same frequency.
If you know how to use a DSP your can make a "fast" bass slow and a "slow" one fast as far as the room allows. Something close to impossible in the analog times. The idea of many small drivers seems neat but doesn't work well if you want 20Hz in a HT. This does not mean that a wall of low resonance, strong drive, high excursion and heavy cone 10" or 12" will not work, DSP corrected and powered by a dozen amps, sure. There are even very special, mutated 6" woofer with extreme excursions, but they simply do not make sense compared to large cones, starting with production costs.
In the end they are many times more expensive and power hungry than a well made, large woofer. Sure you can transport 10.000 tons of grain over the ocean with 100.000 canoes, but one large ship makes more sense.
In the end it is all about a volume of air that has to be moved.
If the amp can deliver this power and the voice coil can take you are done. Sure, from an economical standpoint, a larger volume is better and needs less amp power. If size is not limited, a Qtc as low as .50 is fine for active speakers.
In the old times, when amp power was rare and cone excursion small, we build huge horn constructions, which gave high SPL, but did not reach very deep when size and weight had to stay transport able. Usually 35 Hz was the lowest we could get with huge 18" bass bins. Which is what rock music needs.
A 20 Hz horn of these times fills the whole basement.
Today power is cheap and chassis can use it. This has lead to completely different aims in speaker construction like tapped horns. Today's speaker cabinets simply do not work with old PA speakers and amps of the time if PA SPL is needed.
Fast bass is a myth that has been proved to be wrong a thousand times. Still some do not get the message. what they consider to be "slow bass" is resonant bass or not time correct reproduction. There is no slow or fast reproduction of the same frequency.
If you know how to use a DSP your can make a "fast" bass slow and a "slow" one fast as far as the room allows. Something close to impossible in the analog times. The idea of many small drivers seems neat but doesn't work well if you want 20Hz in a HT. This does not mean that a wall of low resonance, strong drive, high excursion and heavy cone 10" or 12" will not work, DSP corrected and powered by a dozen amps, sure. There are even very special, mutated 6" woofer with extreme excursions, but they simply do not make sense compared to large cones, starting with production costs.
In the end they are many times more expensive and power hungry than a well made, large woofer. Sure you can transport 10.000 tons of grain over the ocean with 100.000 canoes, but one large ship makes more sense.
In the end it is all about a volume of air that has to be moved.
just ordered 2 um15
Cost more than I wanted, but figured I’d be crying once. 😂
There a couple thing that need to be clarified and figured out still.
1- decoupling material between table(box)/legs/carpet
2- type of connector I’m going to use: speakon or banana. Where to install them on the box.
3- is there any benefits to have 1 speakon per driver or 1 set of banana per driver.
4- worth putting double baffle ?
5- Finishing designing grill
6- brace: do I need to brace the angled “middle” separation.
7- to screw the driver: wood screws vs t-nut?!
Cost more than I wanted, but figured I’d be crying once. 😂
There a couple thing that need to be clarified and figured out still.
1- decoupling material between table(box)/legs/carpet
2- type of connector I’m going to use: speakon or banana. Where to install them on the box.
3- is there any benefits to have 1 speakon per driver or 1 set of banana per driver.
4- worth putting double baffle ?
5- Finishing designing grill
6- brace: do I need to brace the angled “middle” separation.
7- to screw the driver: wood screws vs t-nut?!
(1) I was afraid that someone would come up with that "fast bass is a myth"... that's why I brought up the handicap of the "heavy cone"... Oh well, not everybody wants planars or multiple speaker towers ( btw, listen to some of those 2 1/2 speakers.... they sound really good and are... "fast" ). "fast bass" is accurate bass.
(2) DSP, room correction, IMHO, it's all a panacea. Just give me the simplest system, good sounding speakers, a good sounding room and I don't need to "fix anything"... the only complexity belongs in the DAC side of the house... you can't help that one. For HT you also need to deal with the surround field decoder... but again, nothing you can do with that. I think of it as a multi channel DAC.
(3) I did hedge myself when commenting on an array of small drivers.... is this for music ( where lots of small drivers are good) or for an LFE's BOOM BOOM channel? In which case all bets for accurate bass reproduction of music are off.
(4) What makes more sense? A single 380 or three 787-9's ( aka 789 ) ? The airlines have made their choice. Big is not always better.
(5) In the end is not only how much air is moved... but HOW it is moved. The acoustic wave should follow the electronic signal clearly, with no static friction delay ( getting the cone to move ) or overshoot ( getting the cone to stop and turn around ). In this case, a large array of small drivers with powerful coil magnets is the way to go... sure, it IS expensive, very expensive, which is why you don't see it as a mainstream commercial product.... but you do sort of see it in High End ( Nola, Infinity bass towers, but at that price point they are big enough and expensive ) and sort of in some speakers with multiple woofers. we don't see in the HT because the LFE is "fake movie bass". Of course, there's always the Maggie Bass Panels... or the 30.0: you get your bass and your room dividers, all in one shot. ;-D
OP: good luck with your shaker table. Do you really want to decouple the table from the floor? I'd figure that being on a crawl space wooden joist floor you'd want to get the whole room moving a little bit as well. Read the Internet comments about how to use Buttshakers and other such.
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1) Unless you can calculate or empirically find the correct amount of vibration damping required, the norm is to mass load it with removable weights such as a decorative marble top, etc.; 'on the cheap' use/make a wood framed tile mosaic or concrete slab and finish it to 'taste', i.e. use your imagination. 😉
That said, a few times I've posted 'somewhere' my experience with a suspended (floating) floor at VLF frequencies down to ~14 Hz (somewhere around 115-120 dB IIRC) where I found out the hard way what its Fs apparently was when the drywall/heavily stippled ceiling and all the stuff stored on it came 'raining' down on us during a U-571 movie depth charge scene, so 'caveat emptor' WRT your performance goals. Got banged/scraped up pretty good, but thankfully no serious injuries from the heavier stuff that hit the sofa as we dived to the floor.
2, 3) From experience WRT UL/CSA testing, steer clear of banana plugs and when it doubt look to what's used in the industry or speakON or similar, though technically overkill in a HIFI/HT app where drivers, amps have more than adequate connectors for their ratings.
4) The smaller the baffle, the stiffer the combined driver/baffle, so no need for a double baffle, but bracing the driver to the cab to mass load/damp it is beneficial for even low power apps, so I consider it essential for high power apps.
5) ???
6) It may need a diagonal 'T' bar stiffener depending on its size/aspect ratio, though when it comes to bracing; my motto is 'when in doubt'......
7) Machine screw inserts for modern high power apps and maybe do use the double baffle if not using at least 3/4" (1.8 cm) thick marine, apple or Birch plywood (don't have any 'hands on' experience with these ultra high Xmax drivers).
1) Gotcha, so I guess i wont be decoupling it! haha.
2-3) so speakon it will be, Do I need 1 speakon per driver? so 2 connection on the sub to power both driver ? or 1 speakon what wil lpower both driver.
4) yes, plenty of bacing will be added, so baffle will be braced too.
5) just putting it out there.
6) oh yeah, didnt think of that. was thinking of verticaly, but yeah, diagonnaly or horizontaly would be much simplier.
That's an interesting paper. it's a good first approximation. Ideally, they would have built a different, larger voice coil to drive the heavier speaker cone. Keeping the resulting sound pressure level constant.
My comments:
(1) "It turns out that transient response of a woofer is not a function of the moving mass, as is commonly espoused (one of the most infamous audio myths). In actuality, it is based upon the inductance of the driver. And the greater the inductance, the slower the driver - the lower the transient response..."
(2) Mass is assumed to be constant.
The first one is quite true, the higher the inductance, voice coils have high inductance, the slower the change of current and the slowest the response. Larger, heavier cones require -as a rule of thumb (*) - more force to drive them and a larger voice coil... hence, higher inductance.
The second one is just an approximation. The moving membrane of the speaker ( cone, flat panel, folded ribbon ) doesn't have constant mass through its geometry. Cones, in particular are the worse as they are driven from the center and supported by the spider and the surround. There is a wave that travels from the center to the edge with a corresponding return wave, that makes the cone break up all over the place and its mass is no longer constant. This can be fixed with stiff materials -aluminum, beryllium, Harbeth's RADIAL, etc...-, surround materials, but it's hard and expensive to make large cones of such materials.
However, for the purposes of the discussion we can simplify this and state that:
The lower the mass of the driver the less force required to drive it.
++++
The bottom line thus is that a smaller, stiffer CONE with a smaller motor assembly will follow signal more closely -those time measurements prove it.... the lighter cone allows for a smaller motor, which has less inductance, ergo less time delay.
To compensate for the lower acoustic output you simply add more drivers and more power...
++++
Of course, there is another way... move to a planar, LARGE planar drivers Their very thin diaphragms, like Mylar, are very light and driven not from a coil but by a planar magnetic field from stators or a long, thin magnet.. which are very quite different from a coil. Given the very light mass of the diaphragms, and the low self induced capacitance of the "magnetic motor", you have very little time delay.
Of course, the reason why we don't see many planar woofers is the restricted travel of the planar membrane, so to make it move lots of air it must be BIG... quite big... ergo stuff like the Maggie bass panels, the 30s and the Timpani, big Martin Logans. And also they need lots of power since they are nowhere as efficient as a wound voice coil. So, unfortunately, for the vast majority of people, a planar woofer is undesirable and/or impractical.
I don't think anyone has been able to make a woofer with ribbons or the Walsh design. The later is in reality sort of a cone.. but I do know that some ribbons go well into the midrange and they are fast! It would be interesting to see a ribbon woofer... might end up being quite large, though.
The article did not go into cabinet design, which can also help by using a horn to amplify the music...
++++
I think the bottom line is that for a cone driver, making the voice coil less powerful (smaller?) lowers phase delay between the driver's movement and the signal applied. Since the resulting force of a smaller voice coil will be lower, then it is important to lower the driven mass of the speaker.
F = ma.
So, yes, the lighter speaker will exhibit less phase shift.
Again, not because of its weight per se, but because of the increased self inductance of the larger voice coil.
Or. just move to a different geometry... there's a reason why the term "Magnepan Bass Slam" was coined.
(*) Sure, sure, there are materials that can help this. But the physics on this are fundamental.... mass is mass, the larger the cone, for a given mass and geometry, the larger the mass.
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I usually would not answer if it was not for the confusion you do to a very straight forward, high performance HT sub woofer build of an inexperienced builder who is just spending a lot of money.
See Mr. Slow Bass, in your world a 1 ton car with 100 HP with a 0-60 time of 7 seconds accelerates faster to 60 mph than a 2 ton car with 400 HP which does it in 4 seconds. We all know about these driver of a cheap old rusty weak car, bragging he is faster than the neighbors Porsche he never can afford. Sure he find all kinds of funny arguments to proof it. You obviously need to promote your car, but reality is something else...
Electrostatic speakers are a different principle which can give exceptional results, while their set up is quite challenging, just as the correct coupling to dynamic woofers. They are expensive and have a limited life time.
What electrostatics can not do is to change the principle of physics. If a 50 Hz frequency is too slow it may be a 40 or 35 Hz frequency but not 50 Hz any more.
Even you must except that this is true. A lack of physical understanding may give you a wrong idea about the movement in time of a cone. Just the same problem that people had when they were sure the world was flat, because they trusted the first impression they got of it...
Maybe you once get a tone generator with a test speaker and turn it down until the cone gets so slow you can see it moving while changing the amplitude. Could be an eye opener for you.
You may dislike DSP and call CD reproduced music artificial sounding. We live in a free world, do as you like, but digital will not go away and you can not listen to any music made today or in the last 30 years that was not digitalis ed on it's way to your medium, may it be vinyl, tape or wax.
If we put a DSP in an active set up of a "Maggy" and a sub, we can delay the foil or the cone as we like. When the delay is adjusted right, at the listeners ear both signals, from front of foil and cone, arrive at the same time. Exactly what happens at the x-over frequency, where both sound producing parts are working. The same can be done without a DSP, carefully matching the distances of low and high frequency producing device.
Depending on the listening room there will be some reflections of the low frequency contend that disturb what you hear. That is what you call "slow bass", which we can measure as frequency dependent boosting or muting at the listening spot and can see in a cumulative spectral decay or "waterfall chart".
What you do not realize, this is exactly the same physics that make you like your "Maggys", which are dipoles. They are throwing any sound they produce at the front to the back to the rear wall as well, just 180° apart, which the hearing may interpret as room information. Which explains the problems of matching electrostatics to a room.
I suppose people have told you this before and you ignored it. If you are my customer and have such ideas, as a sales man I will not correct you, but try to sell you things that make me a nice profit. So you will always find people that agree to your personal Voodoo view. The always unhappy high end HIFI friend is the most loved customer...
See Mr. Slow Bass, in your world a 1 ton car with 100 HP with a 0-60 time of 7 seconds accelerates faster to 60 mph than a 2 ton car with 400 HP which does it in 4 seconds. We all know about these driver of a cheap old rusty weak car, bragging he is faster than the neighbors Porsche he never can afford. Sure he find all kinds of funny arguments to proof it. You obviously need to promote your car, but reality is something else...
Electrostatic speakers are a different principle which can give exceptional results, while their set up is quite challenging, just as the correct coupling to dynamic woofers. They are expensive and have a limited life time.
What electrostatics can not do is to change the principle of physics. If a 50 Hz frequency is too slow it may be a 40 or 35 Hz frequency but not 50 Hz any more.
Even you must except that this is true. A lack of physical understanding may give you a wrong idea about the movement in time of a cone. Just the same problem that people had when they were sure the world was flat, because they trusted the first impression they got of it...
Maybe you once get a tone generator with a test speaker and turn it down until the cone gets so slow you can see it moving while changing the amplitude. Could be an eye opener for you.
You may dislike DSP and call CD reproduced music artificial sounding. We live in a free world, do as you like, but digital will not go away and you can not listen to any music made today or in the last 30 years that was not digitalis ed on it's way to your medium, may it be vinyl, tape or wax.
If we put a DSP in an active set up of a "Maggy" and a sub, we can delay the foil or the cone as we like. When the delay is adjusted right, at the listeners ear both signals, from front of foil and cone, arrive at the same time. Exactly what happens at the x-over frequency, where both sound producing parts are working. The same can be done without a DSP, carefully matching the distances of low and high frequency producing device.
Depending on the listening room there will be some reflections of the low frequency contend that disturb what you hear. That is what you call "slow bass", which we can measure as frequency dependent boosting or muting at the listening spot and can see in a cumulative spectral decay or "waterfall chart".
What you do not realize, this is exactly the same physics that make you like your "Maggys", which are dipoles. They are throwing any sound they produce at the front to the back to the rear wall as well, just 180° apart, which the hearing may interpret as room information. Which explains the problems of matching electrostatics to a room.
I suppose people have told you this before and you ignored it. If you are my customer and have such ideas, as a sales man I will not correct you, but try to sell you things that make me a nice profit. So you will always find people that agree to your personal Voodoo view. The always unhappy high end HIFI friend is the most loved customer...
Oh boy.. lots of non sequiturs and ad hominem attacks. How come people can not be civil when confronted with an analysis that runs counter to their beliefs?
As a rule of thumb I don't buy commercial products. Speakers and cartridges tend to be rare beasts... I don't know that any one has ever built a dipole..
Oh, dipole? What's that?
The discussion started because I brought up the point that perhaps instead of building subwoofer with a larger driver a more useful approach to his living room would be an array of smaller drivers. Do you have an issue with that? The OP might build the perfect table top subwoofer but it will overpower his 10x10 room.
DSP... I stand my ground.
Digital I stand my ground. DACs.
( Note: I have built -with VHDL- and programmed DACs, btw...).
BTW, I stand by my physics. Can you refute that or are you simply into ridiculing me?
BTW, it's a "Maggie", not a "Maggy". At least, get THAT right.
OH, I have a pair of Entec MX-5s btw.... hardly a "dipole" and a very fast bass response because they use a phase locked loop correction.
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Stand your physics, even if they do not match real physics. It is a free world, anyone can choose a religion* and even found a new one if he want's to.
* at least in a few parts of the world
* at least in a few parts of the world
Did you even READ THE PAPER GM posted a link for? Or you just like to belly moan?
https://www.adireaudio.com/wp-content/uploads/2018/12/Adire-Audio-Woofer-Speed-by-Dan-Wiggins.pdf
Why don't go read it before you go off you deep end.
I know, you have chosen your religion.
For those who do not believe in witchcraft, there is an interesting problem to think about:
We take a perfect speaker for low frequency and place it inside a room. We consider it to be the "fast bass" whatever that may be. Now the task you to turn it into a "slow bass", while keeping the level constant. What would you do to that speaker and why? What physics makes the same frequency slow or fast?
Of course there is good and bad bass reproduction, anyone knows that, but the definition of fast or slow is misleading. "Dry" may be an acceptable description for a less resonant bass.
Some people have heard the same sales talk all their life and stick to it. Some sell their products with it, I know.
Like Coke is fresher than Pepsi...
PS maybe read the paper you posted. It explains why there is no fast bass. https://www.adireaudio.com/wp-content/uploads/2018/12/Adire-Audio-Woofer-Speed-by-Dan-Wiggins.pdf
For those who do not believe in witchcraft, there is an interesting problem to think about:
We take a perfect speaker for low frequency and place it inside a room. We consider it to be the "fast bass" whatever that may be. Now the task you to turn it into a "slow bass", while keeping the level constant. What would you do to that speaker and why? What physics makes the same frequency slow or fast?
Of course there is good and bad bass reproduction, anyone knows that, but the definition of fast or slow is misleading. "Dry" may be an acceptable description for a less resonant bass.
Some people have heard the same sales talk all their life and stick to it. Some sell their products with it, I know.
Like Coke is fresher than Pepsi...
PS maybe read the paper you posted. It explains why there is no fast bass. https://www.adireaudio.com/wp-content/uploads/2018/12/Adire-Audio-Woofer-Speed-by-Dan-Wiggins.pdf
Jeez man...
(1) I didn't post that article. It was posted by GM and he pointed it out for us to read. Your "experiment" is a logical fallacy because it's a non sequitur.
(2) GM's link deals with physics and electronics at a simple, yet interesting level. Did you really read, and understand, it? Did you follow the arguments that it presents? Did you understand the time/phase shifts? Do you understand the correlation between the motive power of a coil and its self inductance? If you did, then you would follow my follow on considerations. I seriously doubt you followed it (or read it carefully... or even read it).
(3) What does religion have to do with the ability of speakers to faithfully follow the input signal with no phase delay?
OP:
Please ignore all of this. Just enjoy your woofer. Again, I'd think you might not need to isolate it from your floor since it's joists.
Did you decide on the amplifier? You can get the NCore eval boards for a very reasonable price and they are quite powerful.
Just butting in here for a nano-second.
If "Fast Bass" is the one with no hangover and a fast return to rest/no ringing then there is such a thing.
But for most of us it's a storm in a teacup, due to being unable to afford these excellent drivers.
A 30Hz wave form is a 30Hz waveform etc: etc: etc>
If "Fast Bass" is the one with no hangover and a fast return to rest/no ringing then there is such a thing.
But for most of us it's a storm in a teacup, due to being unable to afford these excellent drivers.
A 30Hz wave form is a 30Hz waveform etc: etc: etc>
The tread starter already has an amp. Reading the thread helps if one wants to add something useful.
A very capable Class D amp with a DSP and very comfortable 2x 1000+x watt rms.
He has also ordered his two 15" chassis with a static Le of 1.3mH. The amp will not have any problems at all to move the 280gram cone "fast" enough with more than 2kW program power. 2kW are usually enough to move even a fat butt on a scooter.
Maybe not fast enough for anyone, scooter and cone...
A very capable Class D amp with a DSP and very comfortable 2x 1000+x watt rms.
He has also ordered his two 15" chassis with a static Le of 1.3mH. The amp will not have any problems at all to move the 280gram cone "fast" enough with more than 2kW program power. 2kW are usually enough to move even a fat butt on a scooter.
Maybe not fast enough for anyone, scooter and cone...