Raising Subwoofer impedance

[Zach Hutkin]

I have two rockford fosgate p1 4 ohm subs and an mtx thunder 302 amp powering them. The amp is two channels and puts out 75x2 watts rms at 4 ohms or 300 watt rms bridged into 4 ohms. right now i am using one channel per sub, but the subs are 150 watt rms. would it be beneficial to try and increase the impedance of the subs to 8 ohms, bridge the amp, and run the subs in parallel. If so how could I increase the impedance?

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[-01limited- 10+ year member]

You cant just change the impedance. You can wire them to get different ohm loads. But this is all dependent on the number of coils your sub has and what ohm they are.

 

[Bettr n' Revrse 5,000+ posts]

O dear where to start.... Ummm you cant change the impendance of a sub onless you change the VC... If you could run them at 8 ohms it would give you less power not more... and dont bridge the amp if you wire them together since that will put your amp at 2 ohms which it is not stable at 2 ohms bridged

 

[ahole-ic]

I say bridge them. You are getting a little cancellation running them in 2 channel mode. If you have 2 single 4 ohm woofers you're correct in assuming they will be at a 8 ohm final impedence. It won't decrease your power output. It will be the exact same as it is now. Each channel is seeing 4 ohms now.

Anyways, to achieve this, on your amp it should tell you what terminals to use to bridge. You are going to only use 1 positive and 1 negative. Take the positive and go to the positive of one sub. Take the negative and go to the negative of the OTHER sub. Then wire the remaining terminals of the subs (each sub should still have a terminal not connected to anything) to each other. So, you can see that the current must flow out of the amplifier, through one subwoofer, into the other woofer, and then back to the amplifier. This is series wiring.

Enjoy your newfound deebeez.

 

[Bettr n' Revrse 5,000+ posts]

Could just get a new amp that will actually work well for them

 

[ahole-ic]

Could just get a new amp that will actually work well for them

He may not have the cash for that.