4ohm and 8ohm

[DANNY8]

I don't know much about stezza's.....but when I bought my old one (which got flogged after a while), the guy at the shop said if I got the 8ohm series subs, I could wire them in a series and run them bridged off the 2channel 4ohm amp. It ran sweet and the subs cranked.....then someone thought they needed them more then me and one night when the car got left out (next to the house instead of in the yard), someone helped themselves to it all.

It was a JL e2150 amp, and 2 JL 12WO 8ohm subs (more stezza gear got nicked, but this gear is all I need help with). Today I bought another e2150 amp off a mate, and a 4ohm 12WO, plus we already have another 4ohm 12WO.....I'm just wondering if we can still hook the 4ohm subs up and have them crank like my old 8ohm ones? Could I just hook each sub into one channel each (2 channel amp), would it sound the same as the old setup?

As soon as I make a box we'll start playing around with it, but just thought I'd ask.

[Ra1d]

not sure if i get what you mean here boss, a 4 ohm load is better that an 8 ohm load.

[commsirac]

Id of thought the two 8 ohm subs ought to be wired in parallel.

[DANNY8]

The old setup was a 4ohm 2ch amp, and 2x 8 ohm subs. I had one sub bridged off the amp, then the other sub was pretty much wired off the first sub, which apparently is called a 'series' or sumfin. But yeah it cranked hard.

The new system is the same but I have 2 4ohm subs instead of 8ohm. So as the only thing different between the subs is the voice coils being 4ohm instead of 8ohm, I figured I should be able to have cranking the same. If I did the same thing to these subs, bridge one sub off both channels then piggy back the 2nd sub off the first, then would it be 2ohm maybe? Coz the amp says '2ohm min' on it, so I guess it should still work?

Sry to be confusing

[commsirac]

The old setup was a 4ohm 2ch amp, and 2x 8 ohm subs. I had one sub bridged off the amp, then the other sub was pretty much wired off the first sub, which apparently is called a 'series' or sumfin. But yeah it cranked hard.

The new system is the same but I have 2 4ohm subs instead of 8ohm. So as the only thing different between the subs is the voice coils being 4ohm instead of 8ohm, I figured I should be able to have cranking the same. If I did the same thing to these subs, bridge one sub off both channels then piggy back the 2nd sub off the first, then would it be 2ohm maybe? Coz the amp says '2ohm min' on it, so I guess it should still work?

Sry to be confusing

The way you describe the connection: wired off the 1st sub, sounds like a parallel connection. Having two 8 Ohm subs wired in series would create 16Ohms of resistance which whether bridged or not wouldnt work too well with a car amplifier.
You really need to check what the specifications of your amp is for bridged mono operation. The 2 Ohm min, perhaps refers to stereo operation....it depends on the design of the amp. The safest way to go would be to just run the 4 ohm subs off each channel, or put them in series for bridged mode. However, if the amp is 2ohm capable in bridged mode you will get the most power using the two 4 ohm subs wired in parallel.

[SweetWagon]

The old setup was a 4ohm 2ch amp, and 2x 8 ohm subs. I had one sub bridged off the amp, then the other sub was pretty much wired off the first sub, which apparently is called a 'series' or sumfin. But yeah it cranked hard.

The new system is the same but I have 2 4ohm subs instead of 8ohm. So as the only thing different between the subs is the voice coils being 4ohm instead of 8ohm, I figured I should be able to have cranking the same. If I did the same thing to these subs, bridge one sub off both channels then piggy back the 2nd sub off the first, then would it be 2ohm maybe? Coz the amp says '2ohm min' on it, so I guess it should still work?

Sry to be confusing

The wiring your talking about is 'parallel'. by running the 8ohm subs in parallel it was creating a 4ohm load to the amp, which is only stable at 4ohm when bridged (although 2 ohm stable nominally per channel).

With your new 4ohm subs, by wiring them the same it will create a 2ohm load and overload the amp.
The subs are rated at 125Wrms(4 or 8ohm models i beleive)
amp is: 70 watts x 2 chan. @ 4 ohms
220 watts x 1 chan. @ 4 ohms (Bridged)

so you could try running each sub of individual channels (55wrms underpowed) or bridge one sub only (95wrms overpowed) and see what sounds best but make sure you adjust the gains.

either way its not ideal, and as you can see before with the 8ohm subs, when bridged they were only 25wrms from their recommended power handling.

[RUN41T]

A 4ohm stable 2 Channel isnt ideal to be running the 2 subs, maybe invest in a monoblock? Will make the subs come to life!!!!

[DANNY8]

Thx heaps for the help guys...I had another look at the amp last night and yeah it's only 4ohm stable when bridged, and 2 ohm minimum for each channel.

I'll build a box within the next few days, then when I get my van back 2morrow(hopefully) I can hook the amp and subs up and have a play.

[garfa]

not sure if i get what you mean here boss, a 4 ohm load is better that an 8 ohm load.

not really, there is better cone control (damping) with an amp driving a high impediance.