Sub at 4 ohms vs. 1 ohm

[mafia29]

I have a JBL 1202D

I have it wired at 4 ohms

would it be better to wire it at 1 ohm?

Will it draw less current at 1 ohm?

According to my calculations

Current (I) = Voltage (V) * Resistance (R)
I = 12v * 1 ohm = 12 Amps
or
I = 12v * 4 ohm = 48 Amps

SO which draws more power or is that not relevant, as voltage is always constant supply at 12 volts?

[Corollacrazy42]

If your amp is on a higher independence it is going to be putting out less power which in turn will mean less current draw. More then likely the amp will be most efficient at its 1ohm setting if it is stable there. In all honesty it should be pulling pretty much the same amount though. My Blau is rated at 41amps and 4ohms bridged.. somewhere around 700w. If that gives you any sort of thing to go by.

[mafia29]

Using a factory HU

the amp is
JBL GTO75.2 II

97 watts RMS x 2 channel at 4 ohms
and ≤ 1% THD + N

145 watts RMS x 2 channel at 2 ohms,
14.4V supply and ≤ 1% THD + NSignal-to-Noise Ratio82 dBA (reference 1 watt into 4 ohms)
Dynamic Power190 watts at 2 ohms
Effective Damping Factor6.39 at 4 ohms
Frequency Response (-3dB)10Hz - 90kHz (-3dB)
Maximum Input Signal5.5V
Maximum Sensitivity230mV
Output Regulation.069 dB at 4 ohms

The sub is JBL 1202D

Power Handling, RMS300 WattsPower Handling,
Peak1200 Watts
Sensitivity93dB
Impedance1 or 4 Ohms depending on wiring

[thoughthard]

That amp has a 4 ohm minimum bridged...

[Curry]

1 ohm = bumpin

anything else = blah

[mafia29]

so i dont think i can put it at 1 ohm.. dont think my amp will handle it

thats what the best buy guyy said...
also what do i set the cross over freq. too?

[Curry]

80hz is usually what people set the crossover to for a sub.

FOrget everything and anything the best buy guy told you...

http://www.bcae1.com/

[javzbumpz]

going under the ohm rating will just cause your amp to clip and never really work. Yes its louder at lower ohms but if ur amp cant handle it its not a good idea. As for the frequency if u like ighter bass go for 80 or lower but if u like that dirty south rattling bass go higher.

[audionut71]

Bridge your amp and run the sub @ 4 ohms. Most likely if you tried to run the amp at 1 ohm it would go into protection or blow fuses (or burn up).
Start w/ the crossover @ 80 Hz and tweak from there, if you like how it sounds at 100, then leave it there, or if setting it at 50 Hz seems best to you then go with that. The point of the crossover is to help the sub blend with the mids and highs.

Your calculations are incorrect. Ohms law is for a steady state circuit, not an amps output. If you were to run an ammeter on your power wire running to the amp you would see that as your impedance drops, your current draw goes up. The amp will always have 12 volts from the battery, the way that it makes more power at lower impedances is by drawing more current. It will continue to do this until one of these things happen:
It blows a fuse (either at the battery or in the amp).
The protection circuitry kicks in.
It burns an internal component.
Which of these things occur first depends on the amp manufacturer and how they have designed the amp to perform. A competion grade amp will be overbuilt (beefier power supply, more/bigger output devices) and dropping to lower impedances will make it get louder and louder. A cheaper amp (that is not overbuilt) will most likely have protection circuits that kick in to stop the amp from melting down.
My guess (i'm not familiar with the JBL amp that you have) is that you are best off running at 4 ohms mono on the amp and 4 ohms on the sub. This (on paper) is the perfect amount of power for the sub (matches its RMS power rating) and it should last a long time this way. If its not loud enough, go get more subs and a bigger amp.
Hope this helps.

[javzbumpz]

i think u really earned the name audio nut. nice info

[mafia29]

thanks alot! it sounds great and thanks for your help!

[audionut71]

Glad it worked out for you.