Get a SPL meter from radioshack and measure the frequency response of your two setup with Room EQ Wizrad and see the actual levels to check for anomoly. It's accurate to within 1db for up to 800Hz compared to much more expensive microphones.
Wow, broken looks even worse than the unmodified response. By the way, could you have picked colours that were even more similar?Yes, this is what I did.
Wow, broken looks even worse than the unmodified response. By the way, could you have picked colours that were even more similar?
I'm surprised by some of the deep nulls that are created by MultEQ XT that didn't exist before. I'll be getting the Onkyo NR5008 which has the MultEQ XT32 and I hope I'll get some decent result out of it. At the moment, with the bass traps I have, I'm about +/-10db from 30hz to 300hz.
Over time down firing or up firing orientations ruins the output of the woofer. When it is used, gravity will amplify the force exerted on the heavy mass of the woofer and it will bottom out sooner than it should when mounted on the side of the box or in this case front firing.Downfiring does reduce xmax a little bit, but generally the downward sag is less than 1mm. You find me a driver that sags 20mm - was it one that you put together in your garage?
You are completely wrong. Sealed is very accurate when comparing the delay. The delay of sealed type of subwoofer is no more than 15 millisecond. If you want to compare vented types, they are about 30 milliseconds and above. It gets worst for passive radiators and bandpass types. Infinite baffled subwoofers are sealed type and have the best accuracy of all types. If want accuracy, it is all about the timing.Sealed subs are not "designed for accuracy", they are used because they are easy to design and construct and tend to be small. A properly-designed vented sub in a room will sound just as good to 99% of the population (there are some freaks out there) and provide up to 6dB extra output down low. Using a Linkwitz Transform can boost the lows of a sealed sub but it will not perform a miracle - max output is still limited by displacement (but you just said Xmax again...) and power requirements skyrocket.
I am not sure which RS model of the 12 inch woofer or 15 inch woofer. Where is the model to hold your statements true. If you were relating to Dayton Audio RSS315HF-4 12 inch woofer, then it is mainly designed for sealed because of its Qes. Sure you can push it to work in a vented box, but it will have poor control. If you were referring to Dayton Audio RSS390HF-4, then it is better for vented. You said that you were using a 15 inch. You were referring to 12 inch.The Dayton RS won't hit low? I already said that the F3 of the vented build I showed to jlee was at 19Hz, are you stupid or just retarded? It'll easily do up to 110dB or more in-room with 300W.
I'll agree that the Shiva X2 has more displacement than a 15" Dayton RS, but:
The Shiva X2 is less sensitive (requiring almost twice the power to achieve the same SPL - 85dB/W vs 87dB/W)
The Shiva X2 costs $50 more
The Shiva X2 ONLY HAS 13% MORE DISPLACEMENT THAN A SINGLE 15" RS
Don't believe me?
12" Shiva displacement = Sd*Xmax = 506 cm^2 (2.6cm) = 1315.6 cm^3
15" RS displacement = 829.6 cm^2 (1.4) = 1161.4 cm^3
(1315.6-1161.4)/1161.4 * 100% = 13.3%
But wait, there's more:
dB = 20 log (1315.6/1161.4) = 1.08
This means that the total max output of the Shiva is only 1dB higher at any given frequency! You can barely listen for that difference, let alone notice it. For his purposes, a single 15" Dayton RS in a vented enclosure is far superior... and cheaper.
You think you are not a troll. You are troll because you are a bully. You are immature that does not know the definition of trolling.nm, best troll ever
First you need to break-in the subwoofer for at least a week or two. Then you can fiddle with Audyssey. It only has been a day or two. Of course the subwoofer's performance will not be good at this time. The suspension is too stiff. You have to break it in to loosen up the suspension.Installed and set up with Audyssey using settings found at AVSforum and it pales in comparison to my Z560's..there's something wrong, and I have no idea what. If I set the volume at 3ish, the receiver adjusts it by -5db after Audyssey. With volume at 5, it's at -9.5db.
It's next to a wall now - rear port about 5" away. I may try moving it to a corner to see what happens, but at this point I think there's some setting or something that I have horribly wrong.
I already said that the sag due to gravitational force on the moving mass is not very high, usually 1mm or less. To pick an example, I'll use the RSS390HF as I have before.Over time down firing or up firing orientations ruins the output of the woofer. When it is used, gravity will amplify the force exerted on the heavy mass of the woofer and it will bottom out sooner than it should when mounted on the side of the box or in this case front firing.
We're both saying that to each other, and I think only one of us can be correct...You are completely wrong.
I never said that sealed wasn't accurate, I said that vented can be just as accurate, practically speaking, with more low-end output.Sealed is very accurate when comparing the delay. The delay of sealed type of subwoofer is no more than 15 millisecond.
Is that so? Then how do you explain this?If you want to compare vented types, they are about 30 milliseconds and above.
Before we get all tangled up, can you please define "accuracy"?Infinite baffled subwoofers are sealed type and have the best accuracy of all types. If want accuracy, it is all about the timing.
You can argue this after you define "accuracy".Vented boxes has output, but it will never have the accuracy of a sealed box.
No it doesn't. I quote here Martin J. King, a leading expert on transmission line speaker theory:If the tunning is very, very low, then becomes a transmission line box.
Belabor this point all you want, but you have shown nobody here why vented subs are less accurate, nor have you described to us what you even mean by accuracy.Vented is designed for loudness, but not accuracy and does not matter how differently you put it. Physics does not allow vented to equal the accuracy of sealed.
All of my figures and discussion have been based around the 15" RSS390HF-4. I do not believe that there has been any confusion here, so I don't know why you keep referring to the 12" version. Correct me if I am wrong.I am not sure which RS model of the 12 inch woofer or 15 inch woofer. Where is the model to hold your statements true. If you were relating to Dayton Audio RSS315HF-4 12 inch woofer, then it is mainly designed for sealed because of its Qes. Sure you can push it to work in a vented box, but it will have poor control.
When?If you were referring to Dayton Audio RSS390HF-4, then it is better for vented. You said that you were using a 15 inch. You were referring to 12 inch.
I can't recall what formula that is, nor its purpose, but the formula that I used to describe a relative percentage is definitely correct. You will have to show me an authoritative source that proves that my figures actually show an increase of displacement by something OTHER than 13% with the Shiva X2 relative to the 15" RSS390... but why would you even try to correct me here? It makes your argument even less relevant.Your calculations are off for the difference between 1315.6 cm^3 and 1161.4 cm^3. It is really the following.
(1315.6 - 1161.4) / (1315.6 + 1161.4) = 0.062 = 6%
Absolutely, and I'm telling you that more watts is more dollars. For jlee, for whom budget matters, an additional $80 (or whatever) for a 500W amp is not justifiable vs a 300W amp.Sure efficiency rules the game on output when caring how much power it will consume. Solid-state amplifiers are cheap on watts compared to vacuum tubes.
All else equal, yes.A 15 inch woofer is better than a 12 inch because it produces the fewest distortion to achieve the same output as a 12 inch.
Absolutely not. Even if the suspension got a little looser because of the higher temperature during operation, this would not cause distortion on its own. Suspension-caused distortion entities generally stem from restoring force asymmetry (variations in Kms(x) - see Klippel white papers).The distortion is caused by the materials used in the suspension.
How was this formula designed and where did you get this? I have never seen this before in my life, and it's pretty stupid when you tack on THD on the end of it, as if the driver or any other device in the audio chain doesn't matter.Also there is distortions cause by the trapped sound waves created on the rear of the woofer inside a box. To calculate the distortion for the box use the following.
0.014*Sd*Xmax/Vb = THD %
Sd = square centimeters
Xmax = millimeters
Vb = liters
Professionals design so that THD does not go above 3%.
I already told jlee it's a 10 cubic foot design and it's been confirmed to work in his situation in terms of space constraints. Don't pick bullshit out of the air.The 15 inch woofer is not any better. There are box size limitations. Using a 15 inch woofer in an apartment will require a lot of space. For a Dayton Audio RSS390HF-4 15 inch woofer in a vented box, it will take about 7 cubic feet to just to make sure it works well. It is tuned around 20 Hz and its delay is about 80 milliseconds. Unfortunately its maximum wattage is 200 watts. It can handle 20 Hz at 108 dB. The length of the ports is about 18 inches and the inside diameter is 4 inches. On terms of space to performance ratio, it is poor. There are better 15 inch woofers that has more output and fits in a small space. The Elemental Designs A5-350 because it fits in a smaller size and it has a lot more output.
This isn't as important for subs as it is for mids and tweeters, but the amplifier should NEVER be driven into clipping (as it can be when it is the primary SPL limiter in the system), regardless of whether its maximum power is above or below the power handling of the driver. If the sub is bottoming out because there's too much power sent to the driver, it isn't a system fault - it's an operational fault because the user doesn't know when to stop with the god damned gain or volume control.Overdriving a subwoofer or designing a subwoofer that hits its Xmax is just bad design. In subwoofer design, the subwoofer should hit under Xmax. If it is not, subwoofer will bottom out and be damage. The subwoofer have to handle peak output with out bottoming. This means there needs some head room to count for the peak output which is unknown.
Bracing isn't for strength, it is to increase the stiffness of the enclosure so that its resonant frequency is moved above the passband of the system so that the enclosure doesn't help to create its own sound when the driver is playing music.Bracing is not always required. It depends on the dimension of the sides of the box. If they are thick enough or strong enough, bracing is not required. If they are not thick, bracing is required. Using 1.5 inch thick MDF for 20 inch cube box does not require bracing. If using 0.75 inch thick MDF, then bracing is required. If using 0.75 inch plywood, then bracing is optional. If the dimension of the sides are bigger, then bracing is required. Sonotubes subwoofers does not need bracing because of the cylinder walls is strong. Same goes true for an subwoofer using a sphere or an egg shape.
I know when I'm trolling. It is my sincerest desire (of today, anyway) that I troll you so much that you leave these forums never to come back. If bullying is necessary to do this, I will bear the sins of my comrades and march on, but it looks like I am not going to have much luck making you leave. By the way, why can't you accept the fact that you're usually wrong?You think you are not a troll. You are troll because you are a bully. You are immature that does not know the definition of trolling.
Over time it will sag more than just 0.78 mm. Then you have to flip it over to sag back into itself. The suspension has its own memory. Like a NiCd, it as its own memory effect. The Xmax will slowly deteriorate and so will the performance of the woofer. It is best to not use down firing or up firing.I already said that the sag due to gravitational force on the moving mass is not very high, usually 1mm or less. To pick an example, I'll use the RSS390HF as I have before.
Cms of driver = 0.28 mm/N
Mms of driver = 282.6g = 0.2826kg
Grav. force of driver = 0.2826kg * 9.81 N/kg = 2.77N
Sag of driver = Cms*downward force = 0.28 mm/N * 2.77N = 0.78mm
0.78mm of sag is hardly anything to talk about. Never mention sag to me again.
You are big ugly troll that should not stuck a nose in some else's business. You should leave it at bay and be humble.We're both saying that to each other, and I think only one of us can be correct...
Now you are changing to a different answer. You change from one answer and then to completely different answer. You sound like a damn woman. Vented will never be as accurate as sealed because of its resonator or the port.I never said that sealed wasn't accurate, I said that vented can be just as accurate, practically speaking, with more low-end output.
Simulations are different compared to real world. You can not depend on them to be accurate. You have to build it. The design you simulate is over dampen and resembles a transmission line. I use Unibox which shows a different picture than WinISD. IMHO, WinISD is not as accurate as UniBox. Unibox shows the ringing or the Q of the design.Is that so? Then how do you explain this?
http://d.imagehost.org/view/0472/rss390_10cubes_14hz
This is the build I gave to jlee, using one RSS390HF-4 in a 10 cubic foot box tuned to 14Hz. Notice that group delay is only 15ms all the way down at 21Hz, only rising below that. You also seem to forget that it is a well-known fact that any given amount of group delay is more and more difficult to discern as frequency decreases.
Accuracy is the ability to produce sound with detail. This means with out having to wait for the object to stop ringing or moving. The ringing is the Q or the transient response of the speaker driver. Your design goes on forever.Before we get all tangled up, can you please define "accuracy"?
..
You can argue this after you define "accuracy".
Even though Martin J. King is an expert in transmission line does not make him immune to be wrong. Basically an over dampen vented is a transmission line. Still no one knows how transmission line boxes actually work. Making a transmission line is still a trial and error process.No it doesn't. I quote here Martin J. King, a leading expert on transmission line speaker theory:
"I define a transmission line loudspeaker as a driver mated to a resonant tube where the natural frequencies and mode shapes of the air in the tube are used to tailor the total system response."
http://www.quarter-wave.com/TLs/Introduction.pdf
The enclosure must be SPECIFICALLY designed to harness the energy of the standing wave. Normal sealed and vented enclosures are ordinarily designed to NOT exhibit this effect, and it is realistically very difficult (and stupid) to end up with a vented enclosure that acts even a little like a transmission line.
A low tune is an ELF (Extended Low Frequency) design, and that's all I have to say about that.
I used the difference and you used the percentage error. The percent error is when measuring a new lab equipment to a known near perfect lab equipment. Though I forgot to include divide by two, so it will be 12% and your calculations are still incorrect.I can't recall what formula that is, nor its purpose, but the formula that I used to describe a relative percentage is definitely correct. You will have to show me an authoritative source that proves that my figures actually show an increase of displacement by something OTHER than 13% with the Shiva X2 relative to the 15" RSS390... but why would you even try to correct me here? It makes your argument even less relevant.
There are cheaper woofers out there with more output than the Dayton Audio RSS390HF-4. The GR Research SW-12B costs $99 and it will perform better.Absolutely, and I'm telling you that more watts is more dollars. For jlee, for whom budget matters, an additional $80 (or whatever) for a 500W amp is not justifiable vs a 300W amp.
Yes THD is cause by trapped sound waves, but it is also cause by the materials of the speaker driver. Let a woofer produce infrasonic and you will hear not the audio signal that the woofer is trying to produce, but the noise of the materials. The materials creates their own sound and this causes distortions. Servo subwoofer tries to decrease these distortions by trying to cancel them out.Absolutely not. Even if the suspension got a little looser because of the higher temperature during operation, this would not cause distortion on its own. Suspension-caused distortion entities generally stem from restoring force asymmetry (variations in Kms(x) - see Klippel white papers).
The main factors causing an increase in distortion when increasing excursion are:
Variations and asymmetry in BL(x)
Variations (or an increase, can't remember) and asymmetry in Le(x)
Asymmetry in Kms(x)
And, as reducing Sd tends to decrease efficiency, the higher power required increases power compression (linear distortion rather than non-linear distortion)
How was this formula designed and where did you get this? I have never seen this before in my life, and it's pretty stupid when you tack on THD on the end of it, as if the driver or any other device in the audio chain doesn't matter.
As far as I'm concerned, the distortion that comes from "trapped sound waves" is from the re-radiation of the sound through the driver and/or enclosure to smear the sound as a delayed source, and this IMO is not a big deal for a sub.
I said 7 cubic feet tuned at about 20 Hz at 200 watts using two (2) 4 inch ports. Do you skim posts or you just prefer bickering. I put it down for dual flared ports. Its wind velocity is 19 meters per second and it is in the frequency range that most people will not hear it. I have verified it in WinISD. Again you are bickering.I already told jlee it's a 10 cubic foot design and it's been confirmed to work in his situation in terms of space constraints. Don't pick bullshit out of the air.
WinISD Pro shows a maximum group delay of 27.6ms at 15.5Hz for an RSS390HF-4 tuned to 20Hz in a 7 cube box. I don't know where your figures are coming from, but either my program is royally fucked up or your numbers are bogus.
Now, my design (10 cubes at 14Hz tuning) shows a power-limited response all the way down to 11.64Hz. That is, the system can handle 500W all the way down to 11.64Hz before excursion limitations are reached. Your "design" at 7 cubes at 20Hz tuning goes down to 14.7Hz at 500W power. Again, show me your graphs or calculations.
Moreover, and this is an exceedingly crucial factor which you have decided to ignore, is that a 4" pipe in a 7 cube box tuned at 20Hz equates to a 57m/s peak port air velocity while 17m/s is the commonly accepted MAXIMUM velocity before port noise becomes significant. Good job, bro.
So you are saying let us all rely on the mechanical limits of the woofer and who cares if we blame the user. This is just plain foolish to the point you have no way on how to design a subwoofer so it can last a long time. Xmax is the linear limits until mechanical limits are reach. Xmax is actually the warning. Going beyond the Xmax increase distortion because not enough magnetic flux to keep it in control. The mechanical limits is the bottoming of the woofer. Going beyond the mechanical limits breaks apart the suspension and this causes damage. As the suspension tears up, the voice coil will start rubbing against the former or the metal gap. It will get to a certain point that the voice coil will short circuit and the amplifier will be tripped into a fail safe mode, hopefully.This isn't as important for subs as it is for mids and tweeters, but the amplifier should NEVER be driven into clipping, regardless of whether its maximum power is above or below the power handling of the driver. If the sub is bottoming out because there's too much power sent to the driver, it isn't a system fault - it's an operational fault because the user doesn't know when to stop with the god damned gain or volume control.
By the way, I'm pretty sure most good drivers have their suspensions set up, in most cases, in such a way that even if Xmax is exceeded, the moving assembly doesn't clip the motor. It takes a certain touch to be able to do it.
You are confuse between bracing and strength. They are both the same thing. By bracing you are technically strengthening the walls, so it does not flex. It is the same thing as adding thickness to the walls of the box. Again you just bickering to be right which you are not right on this one.Bracing isn't for strength, it is to increase the stiffness of the enclosure so that its resonant frequency is moved above the passband of the system so that the enclosure doesn't help to create its own sound when the driver is playing music.
Look whos talking troll.I know when I'm trolling. It is my sincerest desire (of today, anyway) that I troll you so much that you leave these forums never to come back. If bullying is necessary to do this, I will bear the sins of my comrades and march on, but it looks like I am not going to have much luck making you leave. By the way, why can't you accept the fact that you're usually wrong?
Now who is a troll.
Get a SPL meter from radioshack and measure the frequency response of your two setup with Room EQ Wizrad and see the actual levels to check for anomoly. It's accurate to within 1db for up to 800Hz compared to much more expensive microphones.
Did you make this graph manually. If not what software did you use? What model of sound meter did you use? This info might be in your original thread but I am too lazy to dig it out and research it.Yes, this is what I did.
What model is it?
Up here in Canada Radioshack was replaced by The Source. This is the meter they have for sale but I can't find the frequency range of the device even at the Scosche web site.
SCOSCHE PORTABLE SOUND LEVEL DB METER
Would this be suitable to measure my sub's output?
Did you make this graph manually. If not what software did you use? What model of sound meter did you use? This info might be in your original thread but I am too lazy to dig it out and research it.
Thanks,
This thread is turning out to be very interesting.
http://en.wikipedia.org/wiki/Creep_(deformation)Over time it will sag more than just 0.78 mm. Then you have to flip it over to sag back into itself. The suspension has its own memory. Like a NiCd, it as its own memory effect. The Xmax will slowly deteriorate and so will the performance of the woofer. It is best to not use down firing or up firing.
Can't hear you over the crying.You are big ugly troll that should not stuck a nose in some else's business. You should leave it at bay and be humble.
Show me where I contradicted myself. Can't? Figures, you're bitching since you have no valid point to make.Now you are changing to a different answer. You change from one answer and then to completely different answer. You sound like a damn woman. Vented will never be as accurate as sealed because of its resonator or the port.
Oh yeah? Then why did good sirs Thiele and Small go to all that work to devise their modeling system?Simulations are different compared to real world. You can not depend on them to be accurate. You have to build it.
Why, because transmission lines are over-damped vented boxes?The design you simulate is over dampen and resembles a transmission line.
As far as I'm concerned, you haven't used either program. Where are your Unibox simulations that prove my figures wrong?I use Unibox which shows a different picture than WinISD. IMHO, WinISD is not as accurate as UniBox. Unibox shows the ringing or the Q of the design.
What does detailed sound have to do with the requirement of infinite acceleration? You do realize that even tweeters can't stop on a dime, yeah?Accuracy is the ability to produce sound with detail. This means with out having to wait for the object to stop ringing or moving.
Prove it.The ringing is the Q or the transient response of the speaker driver. Your design goes on forever.
Oh, so now you're smarter than MJK about transmission lines? And nobody knows how they work? Go fellate yourself under your bridge.Even though Martin J. King is an expert in transmission line does not make him immune to be wrong. Basically an over dampen vented is a transmission line. Still no one knows how transmission line boxes actually work. Making a transmission line is still a trial and error process.
I've made a mistake here. ELF refers to a sealed system wherein the top end of the passband is where the system starts to naturally roll off. EBS is the vented version, and it stands for Extended Bass Shelf.An ELF take the perfectly flat vented alignment and multiply it by 1.5 times its size. Then tune low. There is another name for ELF is EBS or Extended Bass System.
Explain this:I used the difference and you used the percentage error. The percent error is when measuring a new lab equipment to a known near perfect lab equipment. Though I forgot to include divide by two, so it will be 12% and your calculations are still incorrect.
http://en.wikipedia.org/wiki/Percent_difference
The formula I used is the one shown directly under that paragraph.The general standard of calculating the percent error involves using the absolute difference of the experimental (measured) and theoretical (accepted) values. Then take the difference and divide it by the theoretical (accepted) value to get percent error,
Prove it.There are cheaper woofers out there with more output than the Dayton Audio RSS390HF-4. The GR Research SW-12B costs $99 and it will perform better.
The materials do not cause the "THD", and the noise that is evident during extremely high excursion is spurious noise and is not generally related to the input signal (so it shouldn't be called harmonic distortion). And, what you're trying to say is that by replacing something like a fabric spider with a rubber one, you can eliminate the self-noise of the driver? Even if this is the case (which I highly doubt), servo control would never eliminate it aside from preventing the over-excursion in the first place, not by "cancelling it out".Yes THD is cause by trapped sound waves, but it is also cause by the materials of the speaker driver. Let a woofer produce infrasonic and you will hear not the audio signal that the woofer is trying to produce, but the noise of the materials. The materials creates their own sound and this causes distortions. Servo subwoofer tries to decrease these distortions by trying to cancel them out.
Which one?I got the equation from Linkwitz spreadsheets.
Which one of my points are you referring to?When breaking in any speaker driver, it basically what it means. It breaks the spider and surround. In simple sense during the break-in period it makes small holes in the spider and the surround to make it soft. This is in design, so I do not why you bring up something that is irrelevant to anything that I said.
The actual formula for driver efficiency is:Sd has little affect on efficiency of the driver. The efficiency of the driver relates to the Qes, Fs, and Vas, so Sd has little affect on efficiency. The spec that has the biggest affect on efficiency is Qes. Sd has affect on displacement, but let us bring that up again or shall we not.
So if high output is required and low distortion isn't required, then one should pick a smaller driver with higher excursion? Gotcha.Sd does affect displacement, but Xmax affects displacement too. Xmax is the priority if need displacement and then Sd comes second. The only time when Sd becomes a big factor is when low distortion is required.
Is it always a factor in design? You've never mentioned it before, though, and probably haven't even heard of it, since if you had, you would know that bigger drivers suffer LESS from it.Compression is always a factor in design. The bigger the woofer the more problems it has with compression. I do not know why you bring up compression. It is more of a bickering troll if you ask me.
I'll use as much of the Xmax as I damn well please, thank you very much. Don't tell me how much Xmax to use when you rely on drivers that have to have high Xmax in order to compete.Since you state what causes distortion, why do not you obey them. It is best to use below Xmax than the whole Xmax.
Maybe those figures are right for dual ports, I'll have to confirm when I get home. Don't blame me if you "forget" to say that you're using two ports, though. Putting that side, though, I can come up with any port velocity that I want as long as I restrict the Xmax, but I guess if you're happy with inferior output then it doesn't matter. By the way, port noise is wide-band noise, not bass, so saying that "it's in the frequency range that most people will not hear it" is wrong.I said 7 cubic feet tuned at about 20 Hz at 200 watts using two (2) 4 inch ports. Do you skim posts or you just prefer bickering. I put it down for dual flared ports. Its wind velocity is 19 meters per second and it is in the frequency range that most people will not hear it. I have verified it in WinISD. Again you are bickering.
I'm sorry, your English is just plain incomprehensible at times.So I am wrong to say that you said 12 inch instead you said 15 inch, but you can never say you are wrong because they will just hurt you. Now who is a troll.
Spiders are tough creatures, it takes a rare instance to rip one apart. Bottoming does indeed damage drivers, but the system should be designed correctly so that it never happens, and this should not be by lowering the amplifier power so that excursion doesn't go too high. Instead it should be done by limiting the gain (one solution, anyway), and it's something that can be restricted-access.So you are saying let us all rely on the mechanical limits of the woofer and who cares if we blame the user. This is just plain foolish to the point you have no way on how to design a subwoofer so it can last a long time. Xmax is the linear limits until mechanical limits are reach. Xmax is actually the warning. Going beyond the Xmax increase distortion because not enough magnetic flux to keep it in control. The mechanical limits is the bottoming of the woofer. Going beyond the mechanical limits breaks apart the suspension and this causes damage. As the suspension tears up, the voice coil will start rubbing against the former or the metal gap. It will get to a certain point that the voice coil will short circuit and the amplifier will be tripped into a fail safe mode, hopefully.
The driver only takes 500W in the first place, so even if you're right (which isn't worth confirming here), it's a moot point. Why would you run 1000W into a driver rated for 500W?Clipping is a different problem. I am explaining about how to design a subwoofer so the subwoofer can last. To design a subwoofer at a desire wattage, do not go above about 75% to 80% of the rated Xmax. This is not for amplifier clipping. This is for peaks during a movie or music. Music has the most peaks and the peaks are a lot more than peaks in movies. Your design will not last long as my design because I count for those peaks. The peaks will damage your design more than my design. Let us say that the mechanical limits is 21 millimeters. It will take about 1000 watts to damage my design. Your design will be damage when 500 watts are used.
I swear you're pulling numbers out of a hat. Your design can handle peaks 5 times higher than mine, whatever that means, and my design handles 2.5 what? And why is my design limited to 200W? And 150W for "comfort"? Any more than that and my woofer bottoms out? Seriously, go die in a fire because you have no idea what you are talking about.My design can handle peaks that are about 5 times higher. Yours can only handle about 2.5, so that is about half the performance as mine. My and your design is limited to about 200 watts although your design will need about 150 watts to have some sort of comfort. Any more watts it will bottom out the woofer. It seems I out design your design.
No, I'm not confusing bracing and strength. A well-built box is more than strong enough to last almost a lifetime without bracing. The bracing does reduce the flexing, but not primarily to make the box "stronger"; it's to make it sound better.You are confuse between bracing and strength. They are both the same thing. By bracing you are technically strengthening the walls, so it does not flex. It is the same thing as adding thickness to the walls of the box. Again you just bickering to be right which you are not right on this one.
How many boxes of Kleenex have you gone through so far?You have lost your winning ticket, so go back to your cave troll.
You are. Howard is a guy doing a public service.Now who is a troll.
Did you make this graph manually. If not what software did you use? What model of sound meter did you use? This info might be in your original thread but I am too lazy to dig it out and research it.
Thanks,
This thread is turning out to be very interesting.
Simulations are not accurate. Engineers knows this, so they figure in the tolerance. Thiele and Small provides some part to help simulate. They treated the speaker driver as a circuit and a simulations follow by adding nested circuits to simulate sealed, vented, bandpass, passive radiator.Oh yeah? Then why did good sirs Thiele and Small go to all that work to devise their modeling system?
I helped someone build a subwoofer providing what volume and what tuning frequency. I said it may or may not perform well because of the simulations. The person said it worked great, but I could not to a listen test because of distance problems.By the way, show me a build that you personally did.
It will take me over a week to calculate a design, so I did use Unibox. I also use WinISD Pro Alpha. I do not have to prove that.As far as I'm concerned, you haven't used either program. Where are your Unibox simulations that prove my figures wrong?
I will not upload the images to my server, but prefer to have my name to be anonymous. It is not because of here or anywhere else. For personal stuff, I prefer to be anonymous. I prefer not to have a facebook and myspace account.Prove it.
To explain the difference about difference percentage and error percentage to someone like that should know how to read equations. If you insist on me to lecture on this simple equation, the following is word for word from wikipedia.Explain this:
Using a GR Research SW-12B 12 inch woofer and a 500 watt Bash amplifier. A 3 cubic feet tuned at around 23 Hz. Could use three 3 inch ports at a length of about 31 inches. To make it at this length, a 3 inch flexible pipe can be used with out causing the air to be restricted compared to using elbows. It will cost about $330. Sure it is more expensive, but it is smaller.Prove it.
Distortions are anything that does not make up the signal. The materials adds distortion to the signal even though it is below the loudness of the signal coming from the subwoofer or speaker driver.The materials do not cause the "THD", and the noise that is evident during extremely high excursion is spurious noise and is not generally related to the input signal (so it shouldn't be called harmonic distortion). And, what you're trying to say is that by replacing something like a fabric spider with a rubber one, you can eliminate the self-noise of the driver? Even if this is the case (which I highly doubt), servo control would never eliminate it aside from preventing the over-excursion in the first place, not by "cancelling it out".
It is from the Linkwitz Transform spreadsheet from Linkwitz site.Which one?
Hard to say because you just quote and bicker even though they are just opinions.Which one of my points are you referring to?
Sure you can use that formula, but it will not be near as accurate as the more reputable equations. They are the following.The actual formula for driver efficiency is:
dB/W=20*LOG10((BL*SD)/(MMS*SQRT(RE)))+59.4
Alternatively:
no (percentage) := rho*(Sd*BL)^/(Mms^2*2pi*c*Re);
Hard to explain in a short time frame. I do not have time write up to prove that I am right.So if high output is required and low distortion isn't required, then one should pick a smaller driver with higher excursion? Gotcha.
I already know compression. Compression is caused by the air pressure being greater than the energy of the materials used in the cone. At this point the Sd decreases because the cone is deforming.Is it always a factor in design? You've never mentioned it before, though, and probably haven't even heard of it, since if you had, you would know that bigger drivers suffer LESS from it.
You are only going to make it worst for your self by designing something to linear limits. If you doing any business, your customers will come back and in force you to fix the subwoofer. If you provide head room, customers will come back for more good business.I'll use as much of the Xmax as I damn well please, thank you very much. Don't tell me how much Xmax to use when you rely on drivers that have to have high Xmax in order to compete.
Can not count for everything in design like a subwoofer. Telling anybody to be careful the volume control is not advice. Anybody will happily turn it to max. Any engineer does count the maximum volume and a little bit above the max.Spiders are tough creatures, it takes a rare instance to rip one apart. Bottoming does indeed damage drivers, but the system should be designed correctly so that it never happens, and this should not be by lowering the amplifier power so that excursion doesn't go too high. Instead it should be done by limiting the gain (one solution, anyway), and it's something that can be restricted-access.
All woofers wattage limit is stated in free air or no box. When the woofer is put into a box, the wattage limit changes. It can be lower or higher. It is best to set a desire goal for the wattage handling and then come up with a design that suits that goal.The driver only takes 500W in the first place, so even if you're right (which isn't worth confirming here), it's a moot point. Why would you run 1000W into a driver rated for 500W?
I swear you're pulling numbers out of a hat. Your design can handle peaks 5 times higher than mine, whatever that means, and my design handles 2.5 what? And why is my design limited to 200W? And 150W for "comfort"? Any more than that and my woofer bottoms out? Seriously, go die in a fire because you have no idea what you are talking about.
I will say you are confused and contradicting your self. Bracing does not make it sound better and not any more than using $1000 for speaker cable. Bracing just provides strength to the walls, so they do not flex. Sure bracing can help control the vibrations, so they are minimal.No, I'm not confusing bracing and strength. A well-built box is more than strong enough to last almost a lifetime without bracing. The bracing does reduce the flexing, but not primarily to make the box "stronger"; it's to make it sound better.
Adding wall thickness does indeed increase the stiffness of the box, but not as fast as if you were to put the equivalent mass in internal bracing. If you want to belabor this point I'll have to find the stupid formula for it.
I used Room EQ Wizard and the Analog RadioShack SPL Meter.
http://www.hometheatershack.com/roomeq/
http://www.radioshack.com/product/in...ductId=2103668
There's a bit of a learning curve and some preliminary steps to take before you start rolling, but it's a pretty cool tool. I'm sure I've only scratched the surface of what it can really do.
Nice I assume you can hook up the sound pressure meter to the computer trough a microphone input?
Using a GR Research SW-12B 12 inch woofer and a 500 watt Bash amplifier. A 3 cubic feet tuned at around 23 Hz. Could use three 3 inch ports at a length of about 31 inches. To make it at this length, a 3 inch flexible pipe can be used with out causing the air to be restricted compared to using elbows. It will cost about $330. Sure it is more expensive, but it is smaller.