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SPL vs. SQ - db difference
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sinister audio
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High Society
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sinister audio
- Master of My Domain
- Posts: 2562
- Joined: Sat Mar 19, 2005 9:00 am
- Location: Watertown, South Dakota
- Contact:
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sinister audio
- Master of My Domain
- Posts: 2562
- Joined: Sat Mar 19, 2005 9:00 am
- Location: Watertown, South Dakota
- Contact:
It's not so much an issue of "the product used" - but rather conceptually, what do you want it to sound like?
Very, very often, that "SQ product" is actually more efficient (read: potentially louder) than a heavy-duty, high moving mass SPL sub with that stuff suspension and heavy duty sets of voice coil windings on it... that product is simply built to be abused, where a SQ customer wouldn't even be pushing his product near it's limits ever - it's more a function of what product suits the user's intents - it's not that the "SQ sub is limited in loudness".
It's as simple as this - SQ guys want the frequency response of their system to be equal all across the frequency spectrum, so that it plays recordings accurately and realistically - and that means you're only talking about 110dB, 120dB levels... maybe 130dB - and at that point, you are truly talking about "rock concert" sound levels - if your WHOLE SYSTEM can reach those output levels, you could actually damage your hearing!
On the other hand, the basshead is looking to build a system that has a frequency response that's way exaggerated on the bottom end... how many systems have you heard that have had multiple subs, ported boxes, thousands of watts of power to the subs... and then a pair of coax's (or even factory speakers) running off the HU?
...probably couldn't even break 110dB without tremendous distortion and breakup across eight entire upper octaves... but from 80hz and down, the car is capable of hitting in the 140dB range.
THAT is the difference between SQ and SPL, primarily - not the product.
I would add that typically SQ guys like sealed boxes, because they have a smoother response, that rolls-off earlier, which combines well with the car's cabin gain to yield an overall "flat response".
...sealed boxes work better with subs that are designed with lower resonant frequencies, and lower motor strength, so as not to be overdamped and sound dull.
...ported boxes work better with subs that have high motor strength (the sub must "fight" it's way through the increased pressure forces inside a ported box due to the air mass moving in the port - hence also why ported boxes are larger than sealed ones), and resonant frequency can be higher, since you could always use your port tuning to extend frequency response lower.
Without that alignment, the sub can sound ugly and boomy, not having the control to battle those slightly-out-of-phase pressure forces - I'm sure you've heard bad ported setups before.
So that is ONE consideration with respect to the product differences...
...but the rest of them are more tweaky than fundamental.
I could take an SQ sub and make it hit big numbers, and I could take an SPL sub and use it within it's limits to yield at least a decent SQ system type of sound.
Very, very often, that "SQ product" is actually more efficient (read: potentially louder) than a heavy-duty, high moving mass SPL sub with that stuff suspension and heavy duty sets of voice coil windings on it... that product is simply built to be abused, where a SQ customer wouldn't even be pushing his product near it's limits ever - it's more a function of what product suits the user's intents - it's not that the "SQ sub is limited in loudness".
It's as simple as this - SQ guys want the frequency response of their system to be equal all across the frequency spectrum, so that it plays recordings accurately and realistically - and that means you're only talking about 110dB, 120dB levels... maybe 130dB - and at that point, you are truly talking about "rock concert" sound levels - if your WHOLE SYSTEM can reach those output levels, you could actually damage your hearing!
On the other hand, the basshead is looking to build a system that has a frequency response that's way exaggerated on the bottom end... how many systems have you heard that have had multiple subs, ported boxes, thousands of watts of power to the subs... and then a pair of coax's (or even factory speakers) running off the HU?
...probably couldn't even break 110dB without tremendous distortion and breakup across eight entire upper octaves... but from 80hz and down, the car is capable of hitting in the 140dB range.
THAT is the difference between SQ and SPL, primarily - not the product.
I would add that typically SQ guys like sealed boxes, because they have a smoother response, that rolls-off earlier, which combines well with the car's cabin gain to yield an overall "flat response".
...sealed boxes work better with subs that are designed with lower resonant frequencies, and lower motor strength, so as not to be overdamped and sound dull.
...ported boxes work better with subs that have high motor strength (the sub must "fight" it's way through the increased pressure forces inside a ported box due to the air mass moving in the port - hence also why ported boxes are larger than sealed ones), and resonant frequency can be higher, since you could always use your port tuning to extend frequency response lower.
Without that alignment, the sub can sound ugly and boomy, not having the control to battle those slightly-out-of-phase pressure forces - I'm sure you've heard bad ported setups before.
So that is ONE consideration with respect to the product differences...
...but the rest of them are more tweaky than fundamental.
I could take an SQ sub and make it hit big numbers, and I could take an SPL sub and use it within it's limits to yield at least a decent SQ system type of sound.
Also - I'd differentiate one more thing in your mind -
it's not just "SQ vs SPL"...
...it's also "SPL vs Boom Car".
Quite fundamentally, most competitive SPL systems will not work well as a streetable daily-driven system - too much on the line with respect to port tuning and power.
And similarly, a good boom-car will never work well as a competitive SPL car. Compromises exist between the two cars:
SPL competitors are looking to keep every last tenth of a dB worth of sound energy INSIDE the car so it can stimulate the mic. SPL cars are usually not too loud, if you hear them from the outside - but they hit about 30dB higher than your typical boom car that you'd hear from 5x farther away.
Boom car drivers want it to hit with whatever CD they have, whatever frequency... from low bass make-me-sick-inside, to midbass kick-me-in-the-ribs. That means they need to build a box tuned low enough to handle most of that energy, while still giving them a bit of an efficiency gain.
Note that ported boxes reduce excursion when you play the sub at the box tuning frequency - you might have observed a sub playing loudly at some frequency that didn't look like it was moving much -
SPL competitors on the other hand exploit this. They tune the box specifically to the one frequency that they wish to burp at - which corresponds to some resonant peak in their car they can exploit, and usually up there - above 50hz... creating a one-note-wonder that also creates a great risk of overexcursion at even low power levels below that tuning frequency. Not satisfying for a daily driver, for a real competitive system.
As a result, an SPL subwoofer is one that basically is "all about motor strength", actually benefitting from a high resonant frequency, and who really cares about excursion? It's needed, but what you are left with after fully trading off excursion capability for motor strength is just fine for SPL, thank you.
On the other hand, a boom car sub has a higher requirement for excursion - possibly a lot of it, if you are really going to be cranking it and getting maximum loudness from a single sub - at frequencies that aren't just that one "tuning frequency of the box". It's also going to be able to handle a lot of power - but you'll be using it under its power ratings, not 4x or 5x in excess of it like an SPL competitor would.
If anything, there's a bigger difference between an SPL competition sub and a "boom car" sub, than there is between an SPL competition sub and a SQ sub, actually.
it's not just "SQ vs SPL"...
...it's also "SPL vs Boom Car".
Quite fundamentally, most competitive SPL systems will not work well as a streetable daily-driven system - too much on the line with respect to port tuning and power.
And similarly, a good boom-car will never work well as a competitive SPL car. Compromises exist between the two cars:
SPL competitors are looking to keep every last tenth of a dB worth of sound energy INSIDE the car so it can stimulate the mic. SPL cars are usually not too loud, if you hear them from the outside - but they hit about 30dB higher than your typical boom car that you'd hear from 5x farther away.
Boom car drivers want it to hit with whatever CD they have, whatever frequency... from low bass make-me-sick-inside, to midbass kick-me-in-the-ribs. That means they need to build a box tuned low enough to handle most of that energy, while still giving them a bit of an efficiency gain.
Note that ported boxes reduce excursion when you play the sub at the box tuning frequency - you might have observed a sub playing loudly at some frequency that didn't look like it was moving much -
SPL competitors on the other hand exploit this. They tune the box specifically to the one frequency that they wish to burp at - which corresponds to some resonant peak in their car they can exploit, and usually up there - above 50hz... creating a one-note-wonder that also creates a great risk of overexcursion at even low power levels below that tuning frequency.
Not satisfying for a daily driver, for a real competitive system.As a result, an SPL subwoofer is one that basically is "all about motor strength", actually benefitting from a high resonant frequency, and who really cares about excursion? It's needed, but what you are left with after fully trading off excursion capability for motor strength is just fine for SPL, thank you.
On the other hand, a boom car sub has a higher requirement for excursion - possibly a lot of it, if you are really going to be cranking it and getting maximum loudness from a single sub - at frequencies that aren't just that one "tuning frequency of the box". It's also going to be able to handle a lot of power - but you'll be using it under its power ratings, not 4x or 5x in excess of it like an SPL competitor would.
If anything, there's a bigger difference between an SPL competition sub and a "boom car" sub, than there is between an SPL competition sub and a SQ sub, actually.
