What Affects a Woofer's Bass Response?

[form109]

Originally Posted by MaVo

A big magnet, strong motor means that the speaker will need less watts to achieve the same excursion than a with a weaker motor, its more efficient. This often goes hand in hand with a lower qts value since membranes are not necessarily made heavier when motor strength increases. This in turn means that you can have a flat response in a smaller cab. But if you design all cabs for flat response, a weak motor and a strong motor will sound the same, just the cab size wil be different. Terms like "control over the cone" are misleading, as they make you think a strong motor is needed for sound quality, while this is absolutely false, as it all boils down to correct implementation of the driver.

The Two Drivers most in Question are the JVC Woofer and the Walmart House Brand Car Audio Sub,both have Nothing Special about the Motor Design.

of course with the Walmart Brand sub being a 12",a Lower FS had to be expected.

does Suspension Compliance also count?

the 12" woofer has a Very Compliant Suspension...while the 8" is Very..Very Stiff!

[MaVo]

You can see what influences q here: Thiele/Small - Wikipedia, the free encyclopedia see unter "small signal parameters"

[Borat]

Originally Posted by form109

i have several speaker drivers laying around,and ones ive Experimented with in the Past...


it seems to me that a Weak Motor with a Very Compliant Suspension produces lower bass than a Weak Motor with a Very Stiff Suspension.

it also seems that a Stronger Motor Paired with a Stiff Suspension still goes Fairly low...the Apex Jr Super 8" is a good Example of this to me...(FS around 50 because of stiff suspension,but still able to respond strongly to low Frequencies.)..some Examples Below.

JVC 8" Woofer

Paper Cone,2" Voice Coil,Aluminimum Former,Non Vented Motor.

Foam Surround,Stiff Suspension,Simple Motor

the Woofer's FR drops noticebly below 50 Hz.

No Name 6.5" Woofer

Paper Cone,.75" Voice Coil,Thick Paper Former,Non Vented Motor.

Foam Surround,Very Flexible Suspension,Simple Motor

the woofer's excursion and FR increase Below 50 Hz...and
a fairly low amount of power causes large cone excursion.

Walmart 12" Generic Brand Car Audio Subwoofer Driver

Poly Cone,2" Dual Voice Coil,Aluminimum Former,Grilled Pole Vent.

Rubber Surround,Very Flexible Suspension,Simple Motor.

The Woofer responds strongly to low bass below 30's...sometimes the
excursion seems sloppy and i get the impresion the woofer i doing little
more than Flopping around,(Not Tightly Controlled)

Doe Anybody Have an idea what im getting at?

factors involved for sealed box:

BL^2/Re
MMS
SD
Compliance ( combined - box & suspension )

now while this is only a very small number of factors there are many scenarios for them to interplay which is why most patterns people identify are false.

the closest to capturing the interplay between all these factors in a single equation is the Hoffman's law but it is also not perfect. i have posted my critique of it on AVSForum once.

the approach i advocate is to understand precisely the effect of each of those 4 factors. that is the simplest design approach which is comprehensive.

unfortunately i haven't bothered to write about the correction that Hoffman's law requires on my site but you can read other relevant material to your question there:

DIY-AV • View forum - Electromechanical

[markus76]

Originally Posted by davygrvy

The room be damned, IMO. Consider the placement loading, pi*x, and be aware of your room gain, but please don't modify your response to adjust for a room modal issue. FIX YOUR ROOM INSTEAD.

Good speakers in a bad room make for lousy sound. Modified speakers to suit the room modal issue makes for worse speakers.

Fixing the room comes first but then EQing can help tremendously (if you only need to correct for one listening position). This little device gives great results: DSPeaker-Anti-Mode 8033

Best, Markus