Sub box volume

[badboy6120]

My subwoofer is Kenwood KFC3012 and I use this sub for my home application

My box measurements are :
Width : 14 inch
Height : 14 inch
Depth : 14.5

and as I measured the volume of this box if I wasn't wrong is around 1.5 Cubic feet ( as the sub's manual )

An externally hosted image should be here but it was not working when we last tested it.

but It doesn't have a loud voice

does anyone have any idea about this sub and its best box????

a picture from this sub in its box

An externally hosted image should be here but it was not working when we last tested it.

 

[GM]

This is a high Qt car audio 'one note' woofer, so even a 10x larger sealed cab won't help. It will do much better in a TL, but the trade-off will be a larger, more complex cab, so you up for making one, and if so, how large can you tolerate?

GM

 

[revboden]

What are you using to drive it?

 

[badboy6120]

yet a 250W mosfet amp, but I'm building a 400W for it that has this characters:

POWER RATING at 1KHZ with 0.1* THD = 320W/ 8 ohm, 400W /4 ohm
IMD= *0.008*
THD at 160W into 8 ohm *1 KHZ= *0.005*
THD at 160W into 8 ohm *20 HZ....20 KHZ= *0.05*
FREQUENCE RESPONSE [at 160W/8ohm, *0...-3dB]= 1.5 HZ.....125 KHZ
INPUT SENSITIVITY= 1Vrms
ΙΝPUT IMPEDANCE= 48K
SLOW RATE with input filter= 20V/uS
=SIGNAL TO NOISE RATIO [at 1W/8ohm] *99dBA
= DAMPING FACTOR at 8ohm [15HZ...25KHZ] 196

 

[revboden]

if the dimensions above are external you have ~1cf of volume.

 

[badboy6120]

no they are the internal parameters

 

[badboy6120]

What shall I do???
Do I have to change my woofer??
Do you know anything good?

 

[revboden]

Test it. got an ohm meter? check that the VC resistance is 3.4 ohms. then check that the amp (attached to the driver) is putting out the voltage it should. at half power it should be delivering ~15V AC

 

[bentoronto]

Since you've mounted the Kenwood upside down, you may have to connect the positive wire to the negative terminal to have the music sound right-side up.

 

[revboden]

Since you've mounted the Kenwood upside down, you may have to connect the positive wire to the negative terminal to have the music sound right-side up.

 

[chris661]

A couple of things to check.

If you run a low frequency signal (say, 10Hz), do you hear a whistling sound?
This would indicate a leak, so the cabinet won't perform as a sealed box.

Does the diaphram move visibly when you turn it up with music playing?

You can use bass eq to get more LF extension, but this driver isn't really suited to home use.

I suppose, with such a high Qts, you could try a simple open baffle or U-frame? This would probably give a flatter bass response, at the expense of a lot of efficiency.

 

[bjorno]

yet a 250W mosfet amp, but I'm building a 400W for it that has this characters:

POWER RATING at 1KHZ with 0.1* THD = 320W/ 8 ohm, 400W /4 ohm
IMD= *0.008*
THD at 160W into 8 ohm *1 KHZ= *0.005*
THD at 160W into 8 ohm *20 HZ....20 KHZ= *0.05*
FREQUENCE RESPONSE [at 160W/8ohm, *0...-3dB]= 1.5 HZ.....125 KHZ
INPUT SENSITIVITY= 1Vrms
ΙΝPUT IMPEDANCE= 48K
SLOW RATE with input filter= 20V/uS
=SIGNAL TO NOISE RATIO [at 1W/8ohm] *99dBA
= DAMPING FACTOR at 8ohm [15HZ...25KHZ] 196

Hi,

If you convert your amp to include negative resistance : See the picture where the Qts is set to ~0.5 by adding a negative resistance of -1.8 Ohm and when the box is either a OD-TL or a T-TQWT(extended BW type).

b

 

[bentoronto]

Not sure I follow the previous post (and can't read anything on those tiny thumbnails), but motional feedback (amp output the negative of driver impedance) sure is a great method for making sealed boxes play properly. Particularly appropriate to this speaker because it can suppress the rather high resonance but push the cone at frequencies below that resonance inherently by the design of MF.

Otherwise, there is a "disconnect" trying to drive this compromised speaker design based on a surplus speaker with an over-blown amp.

Ben

 

[bjorno]

Not sure I follow the previous post (and can't read anything on those tiny thumbnails), but motional feedback (amp output the negative of driver impedance) sure is a great method for making sealed boxes play properly. Particularly appropriate to this speaker because it can suppress the rather high resonance but push the cone at frequencies below that resonance inherently by the design of MF.

Otherwise, there is a "disconnect" trying to drive this compromised speaker design based on a surplus speaker with an over-blown amp.

Ben

Hi Ben,

To magnify the thumbnail: Click on the X-cross at the lower left corner.

b

 

[bentoronto]

Thanks. Looks interesting.

I'm in the "usability" business and I love to fall victim to outrageously stupid interfaces. In this case, I had no idea you could magnify the thumbnail until I ran my cursor over the low corner, as bjorno suggested, because that option was invisible (AKA known as alternate modes).

Ben