Fi Q judgement day (SPL #'s inside)

[sku 10+ year member]

Let me give you an example: 2 enclosures with exact same internal volume. One enclosure is very long and the other is very deep. Now think about enclosure loading and acoustic suspension. Partly it is impedance rise, but we can also transfer the energy into the port hence making the port work harder with the help of port resonance. This is a more advanced approach.
Tuan

So Tuan, I'm curious to know what the answer is?

I'm guessing the deep box will allow the air mass to flow into the port more easily or is it the other way around?

Thanks!

 

[tommyk90 5,000+ posts]

Also folks, the testing will continue next week when I receive another box from UPS. //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif

 

[BigJoker 10+ year member]

Also folks, the testing will continue next week when I receive another box from UPS. //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif

another surprise?

 

[tommyk90 5,000+ posts]

another surprise?

maaaaaaaaaaybe. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[Toxic Tuan 10+ year member]

So Tuan, I'm curious to know what the answer is?
I'm guessing the deep box will allow the air mass to flow into the port more easily or is it the other way around?

Thanks!

It really depends on your port placement and orientation. In regards to the deep box, the impedance will typically be lowered and you will have a compression farther away from the woofer.

Tuan

 

[scottyk 10+ year member]

That is insane! Excellent job! From what I've been gathering, these kinda numbers with smaller set-ups are normal for you?

 

[tommyk90 5,000+ posts]

That is insane! Excellent job! From what I've been gathering, these kinda numbers with smaller set-ups are normal for you?

Yeah, the truck is pretty loud with minimal equipment.

With the 9512 and ~700 watts it did a 149.8 outlaw.

 

[slim2fattycake 10+ year member]

i hate s10s. lol. you and ben hemps.

 

[T3mpest 10+ year member]

I don't follow SPL very well, but how will making the enclosure smaller help his score? It's the cones ability to excite the air in the box that leads to port resonace. If the suspension can't send the woofer any further how can you excite the air more by simply making the box smaller and applying more power? That simply makes the system less effecient and take more power to get the same excursion I would think. I mean if he's burping at a frequency that isn't where his port is tuned I can see the issue. However, if he's getting xmech at the same frequency his port is excited at where getting max cone excursion should be the hardest, that should be an optimal system, assuming the airflow in the port and port size has also been maximized as well.

SPL subs as far as I knew use stiff spiders and run high power so they can use very large ports and still not bottom out. However being that stiff they need alot of power to still reach actual excursion values that can excite that much air. If he's hitting xmech in that box then isn't he pretty much dead in the water without sizing up his port and hoping the woofer can drive it properly, or simply maximize airflow with what port he has.

No hate I'm just a SQ guy so I'm actually curious.

 

[tommyk90 5,000+ posts]

I don't follow SPL very well, but how will making the enclosure smaller help his score? It's the cones ability to excite the air in the box that leads to port resonace. If the suspension can't send the woofer any further how can you excite the air more by simply making the box smaller and applying more power? That simply makes the system less effecient and take more power to get the same excursion I would think. I mean if he's burping at a frequency that isn't where his port is tuned I can see the issue. However, if he's getting xmech at the same frequency his port is excited at where getting max cone excursion should be the hardest, that should be an optimal system, assuming the airflow in the port and port size has also been maximized as well.
SPL subs as far as I knew use stiff spiders and run high power so they can use very large ports and still not bottom out. However being that stiff they need alot of power to still reach actual excursion values that can excite that much air. If he's hitting xmech in that box then isn't he pretty much dead in the water without sizing up his port and hoping the woofer can drive it properly, or simply maximize airflow with what port he has.

No hate I'm just a SQ guy so I'm actually curious.

Well theres a couple reasons really.

One has to do with the enclosure size itself. By enclosure size, I mean how much room the enclosure itself takes up. If you look at newer style crx boxes they try to make the box as tiny as possible to maximize airflow around the enclosure itself. That's one aspect of a smaller box.

Also, a smaller box will change its own resonance, for better or worse nobody knows until you test it. Also, going to a smaller box will change the peak frequency, given the same port length. SPL is a funny thing really. For example, one time I tested one of my old SPL enclosures with 2 different port lengths. The boxes have external aeroports so it does not affect the airspace, however with the shorter port I lost upwards of 3 dB. The funny thing about that? My peak frequency didn't change. Like I said, SPL is tricky stuff that involves a lot of testing.

Another aspect of a smaller enclosure is the ability to pressurize it easier. And as we know, higher air pressure=higher SPL. Also, that's why you don't necessarily need to add power to get higher numbers out of a smaller box. Also, a smaller box can develop an "air spring" effect, if you will, that can help control excursion at higher power levels. That's how some people can shove 10kw into a 3" coil and have everything hold together. Of course part of that effect has to do with the port length/size as well, relative to the enclosure size.

When I put my TL inside my enclosure, I can hit upwards of 170 dB. If was to put my 10" in 4 cubes, that number would most likely drop dramatically.

Also, don't think that excursion is the only aspect to high SPL numbers. I can move a CVR (or any other cheaper sub with decent xmax) peak-to-peak and put the DD in the same setup with less power, moving 1/4 as far, and odds are the DD is going to be louder.

Why? Because of motor FORCE. Think of it like this. You can punch a wall gently 1 time every second, or you can punch as hard as you can 1 time every second. In essence the "sine wave" you create by moving your arm back and forth will be the same length and height, but the force behind the 2nd one is much greater.

More force=more SPL.

Going off your statements, one would think that a larger box will always be louder, which we know isn't the case.

 

[T3mpest 10+ year member]

Well theres a couple reasons really.
One has to do with the enclosure size itself. By enclosure size, I mean how much room the enclosure itself takes up. If you look at newer style crx boxes they try to make the box as tiny as possible to maximize airflow around the enclosure itself. That's one aspect of a smaller box.

Also, a smaller box will change its own resonance, for better or worse nobody knows until you test it. Also, going to a smaller box will change the peak frequency, given the same port length. SPL is a funny thing really. For example, one time I tested one of my old SPL enclosures with 2 different port lengths. The boxes have external aeroports so it does not affect the airspace, however with the shorter port I lost upwards of 3 dB. The funny thing about that? My peak frequency didn't change. Like I said, SPL is tricky stuff that involves a lot of testing.

Another aspect of a smaller enclosure is the ability to pressurize it easier. And as we know, higher air pressure=higher SPL. Also, that's why you don't necessarily need to add power to get higher numbers out of a smaller box. Also, a smaller box can develop an "air spring" effect, if you will, that can help control excursion at higher power levels. That's how some people can shove 10kw into a 3" coil and have everything hold together. Of course part of that effect has to do with the port length/size as well, relative to the enclosure size.

When I put my TL inside my enclosure, I can hit upwards of 170 dB. If was to put my 10" in 4 cubes, that number would most likely drop dramatically.

Also, don't think that excursion is the only aspect to high SPL numbers. I can move a CVR (or any other cheaper sub with decent xmax) peak-to-peak and put the DD in the same setup with less power, moving 1/4 as far, and odds are the DD is going to be louder.

Why? Because of motor FORCE. Think of it like this. You can punch a wall gently 1 time every second, or you can punch as hard as you can 1 time every second. In essence the "sine wave" you create by moving your arm back and forth will be the same length and height, but the force behind the 2nd one is much greater.

More force=more SPL.

Going off your statements, one would think that a larger box will always be louder, which we know isn't the case.

I'm good until the last part. Motor force allows a sub to move further when it's playing at the tunign frequency of the port where intertial damping is highest. Anyway if 2 subs move the same amount playing the same tone then I dont' see how it can have more "force" behind it. If it had more acceleration, it would HAVE to move further. The tone will only occilate the cone back and forth a given number of times per second. An increase in motor force would lead to the cone accelerating faster, which means it must be moving further with each stroke. Looking at it that way we can take "motor force" back to a simple function of displacement yet again. You can't create pressure without moving air if we make cone area and the frequency a constant the only factor left for how much air we move is how far the cone moves with each stroke. Granted how much air we can excite via the port is also a factor, but switching just the subs holds that constant too, given the same stroke of couse. Your DD's may move less below tuning due to a stiff suspension, but at tuning I can't see how the speaker can move less yet excite more air.

Anyway use your hand as an example since you brought it up. If you move your hand back and forth you displace air. If you don't move your hand any further with each stroke, what woudl you do to increase "force" like if you were going to hit something. Normally you would simply move your hand back and forth very quickly, but that would increase your frequency since you are moving it back and forth more times per second. That's not allowed. If we then force that to be a constant all we can do is move very fast, very far one way, then in the other half of the time intregral travel back at the same speed. accelation and hence displacement are what changed.....

 

[tommyk90 5,000+ posts]

I'm good until the last part. Motor force allows a sub to move further when it's playing at the tunign frequency of the port where intertial damping is highest. Anyway if 2 subs move the same amount playing the same tone then I dont' see how it can have more "force" behind it. If it had more acceleration, it would HAVE to move further. The tone will only occilate the cone back and forth a given number of times per second. An increase in motor force would lead to the cone accelerating faster, which means it must be moving further with each stroke. Looking at it that way we can take "motor force" back to a simple function of displacement yet again. You can't create pressure without moving air if we make cone area and the frequency a constant the only factor left for how much air we move is how far the cone moves with each stroke. Granted how much air we can excite via the port is also a factor, but switching just the subs holds that constant too, given the same stroke of couse. Your DD's may move less below tuning due to a stiff suspension, but at tuning I can't see how the speaker can move less yet excite more air.
Anyway use your hand as an example since you brought it up. If you move your hand back and forth you displace air. If you don't move your hand any further with each stroke, what woudl you do to increase "force" like if you were going to hit something. Normally you would simply move your hand back and forth very quickly, but that would increase your frequency since you are moving it back and forth more times per second. That's not allowed. If we then force that to be a constant all we can do is move very fast, very far one way, then in the other half of the time intregral travel back at the same speed. accelation and hence displacement are what changed.....

You're not grasping what I'm saying.

Both subs don't move at the same xmax with the same force. This is what separates cheap, good excursion subs from higher power, less excursion subs. Imagine holding your hand against the cone of both subs. The higher motor strength sub will take more pressure from you to hold it back from moving outward.

Take the old XXX for example. Spectacular xmax and xmech due to the xbl^2 design, but didn't meter worth a darn when compared to other subs with less excursion.

DD's are known for not moving nearly as much as other subs, but they can be considerably louder. Why? Because of high motor strength and efficient soft parts.

SPL is not always about excursion, most of the time it's about the enclosure.

Just to give you a concrete example, my DD with 700 watts will do a 149.8 in the kick. At this point the sub is barely moving. Drop in a Q and the score drops over 3 dB with the same amount of power. It takes more than double the power, and subsequently much more excursion, for the Q to catch up to the DD. Moving both subs peak-to-peak (with the DD being the lesser of the two) and the DD is still ahead by over 2 dB. Excursion does not equal SPL. (but to be fair, I haven't tried different enclosures for the Q yet, which could make a considerable difference)

Honestly it's a difficult conversation to have because of all the variables involved. Plus I don't consider myself very knowledgeable on woofer design to really be able to give specific and factual responses to everything.

I just build and test. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[T3mpest 10+ year member]

You're not grasping what I'm saying.
Both subs don't move at the same xmax with the same force. This is what separates cheap, good excursion subs from higher power, less excursion subs. Imagine holding your hand against the cone of both subs. The higher motor strength sub will take more pressure from you to hold it back from moving outward.

Take the old XXX for example. Spectacular xmax and xmech due to the xbl^2 design, but didn't meter worth a darn when compared to other subs with less excursion.

DD's are known for not moving nearly as much as other subs, but they can be considerably louder. Why? Because of high motor strength and efficient soft parts.

SPL is not always about excursion, most of the time it's about the enclosure.

Just to give you a concrete example, my DD with 700 watts will do a 149.8 in the kick. At this point the sub is barely moving. Drop in a Q and the score drops over 3 dB with the same amount of power. It takes more than double the power, and subsequently much more excursion, for the Q to catch up to the DD. Moving both subs peak-to-peak (with the DD being the lesser of the two) and the DD is still ahead by over 2 dB. Excursion does not equal SPL. (but to be fair, I haven't tried different enclosures for the Q yet, which could make a considerable difference)

Honestly it's a difficult conversation to have because of all the variables involved. Plus I don't consider myself very knowledgeable on woofer design to really be able to give specific and factual responses to everything.

I just build and test. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

hmm. So even at tuning the DD's tend to move less than the Q? when just playing a test tone? I was always under the impression high xmax subs dont' tend to meter well because they don't move when it matters for actual SPL scores, when trying to excite a port near tuning. That's why I thought BL and high power handlign was so important. BL makes a speaker move further near resonance with less power and more power handling allows for more excursion in a now usually power limited situation... I dont' have any real-world experience with SPL per-say, more physics and general speaker knowledge.

 

[tommyk90 5,000+ posts]

hmm. So even at tuning the DD's tend to move less than the Q? when just playing a test tone? I was always under the impression high xmax subs dont' tend to meter well because they don't move when it matters for actual SPL scores, when trying to excite a port near tuning.... I dont' have any real-world experience with SPL per-say, more phsyics and general speaker knowledge.

From a peak-to-peak aspect, yes the DD is different from the Q, as are pretty much all other subs out there.

If I had the ability to measure excursion at different power levels I would love to have those numbers.

You probably have more speaker knowledge than I do, I'm still learning about all that. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

In reality all that stuff I posted was just my thoughts and opinions. I really don't know if everything I said is exactly true. //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif

 

[T3mpest 10+ year member]

From a peak-to-peak aspect, yes the DD is different from the Q, as are pretty much all other subs out there.
If I had the ability to measure excursion at different power levels I would love to have those numbers.

You probably have more speaker knowledge than I do, I'm still learning about all that. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

In reality all that stuff I posted was just my thoughts and opinions. I really don't know if everything I said is exactly true. //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif

A laser pointer and a clamp would get you close... Clamp to match actual power levels going to the woofer, burp at your box tuning and compare with a laser sight. Heck you could simply use the laser sight to make simply make sure the DD was moving more or less and then compare scores. If I'm right assuming they have the same actual surface area on the cone, anytime the DD moves further it should meter louder too.