Hey so i got rid of the mofo and picked up a L7, its 10 times better than the mofo, but i have a question... It has dual 4ohm voicecoils, so i have it wired down to 2ohm, is there anyway to wire it down to 1 ohm without having a second sub??? Ive never heard of such a thing but i figured id ask...
Replies (9)
swez on 03/6/2009 04:13:07
Nope, not possible unless you change to the 2+2 DVC version Kicker L7. This sub wired in parallel nets 1 ohm.
What amp are you running now?
Swez
glower0024 on 03/6/2009 13:03:50
Im still running the directed 2400d
swez on 03/6/2009 13:31:51
The Directed 2400D is not 1 ohm stable, but at 2-ohms, it can deliver 2,000 + watts.
Even than, if you went with dual L7 subs, they'd have to be the 2+2 version. These net 2-ohm when wired series/parallel.
Also, these subs love a huge sealed or ported enclosure. If sealed, that's about 2.5 cf/sub. If ported, 5-6 cf/sub are often used. These are heavy and large subs/boxes bud. It takes a large SUV or van to handle such large enclosures. Do you have that kind of space?
Think this over carefully before making a commitment to such a project on this scale. These subs are heavy and a large box will put massive weight into the vehicle. If the suspension cannot handle that weight, adverse handling issues will be an issue. (Sloshy ride)
Swez
glower0024 on 03/6/2009 15:52:45
My amp is 1ohm stable its a mono block amp, i had the mofo 15 wired down to 1 ohm when i had it, but the box i have the kicker in is pretty big, it takes up pretty much the whole trunk of my grand am, what would the measurements for a 5 cubic foot box be?? heres some info on my amp http://www.drdetailshop.com/dd2400.htm
swez on 03/6/2009 19:24:31
Good, that link cleared up the confusion as I found another Directed amp 2400D that stated 2400 watts @ 2 ohms, an not 1 ohm stable.
Again, the Kicker 15" L7 is rated at 1000 watts RMS. The difference in output SPL with 800 vs 1200 RMS is only 1.5 dB. (too little for the human ear to detect above 110 dB of SPL) Adding a 2nd sub will not do much either so that's basically a wash and 2 huge chambers.
A little homework for you so you can learn how box calculations work.
1. Height x Width x Depth/1728 = Gross External Dimensions
2. Then we have to factor in wood thickness, port and sub displacements too. (1" mdf)
3. In a box with large panels, internal bracing is often needed too. We have to factor those in as well.
Example: 24" x 24" x 24" = 13,824/1728 = 8.0 cf (Externally)
This nets a 6.16 cf airspace inside the box minus the sub, port and bracing displacements. By the time these are all factored in, you'll be pretty close to a 5.5 cf box.
FYI: You can manipulate H, W & D numbers as needed for proper fit into the space available. Here's a copy of the manual for 15" SL7:
http://akamaipix.crutchfield.com/Manuals/206/20688L74.PDF
Note the power handling of the sub in a sealed box is 1000 watts RMS. I the ported system, power handling drops to 750 watts RMS.
Read the manual carefully,
Swez
glower0024 on 03/6/2009 22:54:44
i got the measurements of my box and did the math, my box is 5.6cf, another question, when i have my music on at higher volumes the amp will cut out for a second and then cut back on, thats probly from lack of power right???
swez on 03/6/2009 23:30:34
That's one possibility. When voltage drops to an unsafe point, (under 11.5 volts) many quality amps will shut down until voltage comes back in range. Your cars' voltage monitor may not be reacting fast enough to show on the dash voltage gage. Using a remote meter to test realtime changes will give a much better picture of what is really going on.
Another factor is heat. All quality amps have thermal protect circuits. When the operating temperature exceeds the preset limits, the amp will shut down to cool and come back on later. Here, it's best to dial up the amp gain by 0.25 - 0.5 volts and see how the amp reacts. It's difficult to give such details w/o observing the conditions and monitoring what's really going on.
Finally, your box is in range for large sealed or ported use. If the bass is crisp, tight and goes pretty low, you're in the ballpark as is. Where is the amp mounted now? (Trunk, under a seat or other?)
Comments?
Swez
glower0024 on 03/7/2009 15:51:23
when i have the music on while the car is in park the capacitor says 11.3, and my amp is on the back of the box
swez on 03/7/2009 18:22:29
Yep, low voltage is your culprit here. When the engine RPM's are low, so is the supply voltage from the ALT/BAT. (Watts to your amplifier) When you add headlamps and brake lights to the equation, the voltage drops even more and the amp will shut down.
We often recommend the Big 3 wiring upgrade under the hood and that may give you a full 1.5 volt step up at idle. That helps, but most stock ALTs are 50-60% power output until over 2,000 RPM.
One trick guys use, is an under-sized pully on the ALT. (Smaller diameter) This allows the engine RPM to remain low, but more ALT rotational speeds at low RPM. Here, the ALT will put out more watts/voltage at low engine RPM as it spins faster than the crankshaft pully. Hense, more output at low engine RPMs.
The best fix is a H.O. ALT that delivers full power at 1500 RPMs and above. These are common in Hot Rods and DB Drag competitions.
I'll stop here and let that sink in,
Swez
Replies (9)
swez on 03/6/2009 04:13:07
Nope, not possible unless you change to the 2+2 DVC version Kicker L7. This sub wired in parallel nets 1 ohm.
What amp are you running now?
Swez
glower0024 on 03/6/2009 13:03:50
Im still running the directed 2400d
swez on 03/6/2009 13:31:51
The Directed 2400D is not 1 ohm stable, but at 2-ohms, it can deliver 2,000 + watts.
Even than, if you went with dual L7 subs, they'd have to be the 2+2 version. These net 2-ohm when wired series/parallel.
Also, these subs love a huge sealed or ported enclosure. If sealed, that's about 2.5 cf/sub. If ported, 5-6 cf/sub are often used. These are heavy and large subs/boxes bud. It takes a large SUV or van to handle such large enclosures. Do you have that kind of space?
Think this over carefully before making a commitment to such a project on this scale. These subs are heavy and a large box will put massive weight into the vehicle. If the suspension cannot handle that weight, adverse handling issues will be an issue. (Sloshy ride)
Swez
glower0024 on 03/6/2009 15:52:45
My amp is 1ohm stable its a mono block amp, i had the mofo 15 wired down to 1 ohm when i had it, but the box i have the kicker in is pretty big, it takes up pretty much the whole trunk of my grand am, what would the measurements for a 5 cubic foot box be?? heres some info on my amp http://www.drdetailshop.com/dd2400.htm
swez on 03/6/2009 19:24:31
Good, that link cleared up the confusion as I found another Directed amp 2400D that stated 2400 watts @ 2 ohms, an not 1 ohm stable.
Again, the Kicker 15" L7 is rated at 1000 watts RMS. The difference in output SPL with 800 vs 1200 RMS is only 1.5 dB. (too little for the human ear to detect above 110 dB of SPL) Adding a 2nd sub will not do much either so that's basically a wash and 2 huge chambers.
A little homework for you so you can learn how box calculations work.
1. Height x Width x Depth/1728 = Gross External Dimensions
2. Then we have to factor in wood thickness, port and sub displacements too. (1" mdf)
3. In a box with large panels, internal bracing is often needed too. We have to factor those in as well.
Example: 24" x 24" x 24" = 13,824/1728 = 8.0 cf (Externally)
This nets a 6.16 cf airspace inside the box minus the sub, port and bracing displacements. By the time these are all factored in, you'll be pretty close to a 5.5 cf box.
FYI: You can manipulate H, W & D numbers as needed for proper fit into the space available. Here's a copy of the manual for 15" SL7:
http://akamaipix.crutchfield.com/Manuals/206/20688L74.PDF
Note the power handling of the sub in a sealed box is 1000 watts RMS. I the ported system, power handling drops to 750 watts RMS.
Read the manual carefully,
Swez
glower0024 on 03/6/2009 22:54:44
i got the measurements of my box and did the math, my box is 5.6cf, another question, when i have my music on at higher volumes the amp will cut out for a second and then cut back on, thats probly from lack of power right???
swez on 03/6/2009 23:30:34
That's one possibility. When voltage drops to an unsafe point, (under 11.5 volts) many quality amps will shut down until voltage comes back in range. Your cars' voltage monitor may not be reacting fast enough to show on the dash voltage gage. Using a remote meter to test realtime changes will give a much better picture of what is really going on.
Another factor is heat. All quality amps have thermal protect circuits. When the operating temperature exceeds the preset limits, the amp will shut down to cool and come back on later. Here, it's best to dial up the amp gain by 0.25 - 0.5 volts and see how the amp reacts. It's difficult to give such details w/o observing the conditions and monitoring what's really going on.
Finally, your box is in range for large sealed or ported use. If the bass is crisp, tight and goes pretty low, you're in the ballpark as is. Where is the amp mounted now? (Trunk, under a seat or other?)
Comments?
Swez
glower0024 on 03/7/2009 15:51:23
when i have the music on while the car is in park the capacitor says 11.3, and my amp is on the back of the box
swez on 03/7/2009 18:22:29
Yep, low voltage is your culprit here. When the engine RPM's are low, so is the supply voltage from the ALT/BAT. (Watts to your amplifier) When you add headlamps and brake lights to the equation, the voltage drops even more and the amp will shut down.
We often recommend the Big 3 wiring upgrade under the hood and that may give you a full 1.5 volt step up at idle. That helps, but most stock ALTs are 50-60% power output until over 2,000 RPM.
One trick guys use, is an under-sized pully on the ALT. (Smaller diameter) This allows the engine RPM to remain low, but more ALT rotational speeds at low RPM. Here, the ALT will put out more watts/voltage at low engine RPM as it spins faster than the crankshaft pully. Hense, more output at low engine RPMs.
The best fix is a H.O. ALT that delivers full power at 1500 RPMs and above. These are common in Hot Rods and DB Drag competitions.
I'll stop here and let that sink in,
Swez
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