Newbies got a question about ohms

[jkohman 0]

I have 2 sony xplod 10 inch 1200w SVC(330w RMS, 4ohms) subs in a sealed boxed with a sony xplod 1000w 2 ch amp.

Specs on the amp

Model Number: Xm-1652z

165w rms x 2 @ 4 ohms

200w rms x 2 @ 2 ohms

400w rms x 1 @ 4 ohms

OK so i have the subs hooked up to the terminals on the box normally (+ to +, - to -) but i bridged it to the amp. Now my question is since i put both the postive wires from each sub directly into the bridge (BTL +) postive on the amp and the same with the negatives, would that be series or parallel? And would it be 2 ohms or 8 ohms, I know it should be 8 ohms on a 2 channel amp thats not 2 ohm stable bridgeable with 2 4 ohm subs and if it is 2 ohms how has my amp been able to handle this? its been like this for about a year now and hasnt had any problems, I'm bringing it up now because I wanted to see all the different ways to wire subs but i havent seen anyone do this so wondering what you guys think. Thanks

[Jmac 24]

It would be parallel. How has your amplifier been able to handle it? It's all about current. You can safely run 400 Wrms continuously on that amplifier at 4 ohms bridged (40V x 10A). Using Ohm's Law (Power = Current^2 x Impedance or 200 = 10^2 x 2), you can see that you can still safely get 200 watts continuously out of the amplifier at 2 ohms bridged. Also keep in mind a few other factors. First, your subwoofers have a 4 ohm nominal impedance, but that number will actually fluctuate depending on a number of factors (frequency being played, enclosure size, voice coil temperature, etc.) and, in most cases, they will have an impedance higher than 4 ohms each. The other thing is that music is dynamic, so you can exceed voltage and current limitations of the amplifier over short periods of time without causing damage, blowing fuses, etc.

Of course, this is nowhere near an ideal situation. You should think of upgrading your amplifier to something that can operate optimally at 2 ohms ...

[jkohman 0]

Ok now is that 200 watts divided between the subs, meaning each sub gets 100 watts or is each sub getting 200 watts?

And yes i have been thinking about upgrading to a mono block around 650w rms at 2 ohms or just get another one of these amps and just bridge each sub into them. Gonna depend on which ones cheaper. Eitherway should get me to about where i want to be shouldnt it? The only issue is that my lights dim pretty bad during bass drops already and the big 3 has already been done with 4 gauge wire. So i dont know if my alternator can handle an extra amp or a bigger one for that matter.

And i got a little story for you guys, so when i bought my car (98 v6 mustang) the system i have came with the car, and after having issues with it working one day and not the next, i decided to check over everything and opened the inline fuse on the power wire from the battery and noticed that whoever owned the car before me (must have been cheap and/or just plain dumb) somehow used an 8 gauge wire as a fuse and the fuse block was melted. So i cut that one off and put in an 80 amp fuse block (i had lying around) and never had a problem again. Im suprised the thing didnt start on fire it was like that for a month after i had owned it and god knows how long before that.

[Jmac 24]

Yes, it would be 100W per sub. You're better off going with a stereo setup since it would be able to produce more power before audible distortion and be more efficient, so you probably wouldn't have as much of a dimming issue.

The amplifier you're using is a Class AB, which is typically around 50-60% efficient under ideal conditions (of which your setup is not). A modern Class D mono amplifier will be upwards of 90% efficient.

Sony lists the current drain as 40A at 14.4V to produce 165W x 2 @ 4 ohms stereo, which would make it 330/(14.4*40) = 57.3% efficient and that's a best case scenario. It's tough to speculate exactly what the efficiency is of your current setup, however. If I had to venture a guess, I'd say it's likely under 30%, especially since you said it blew the previous fuse to the point where it melted in the fuse block.

If you take a conservative number of 80% efficiency for a Class D amp at 2 ohms producing 650W, that's a current draw of 650W/(14.4*0.8) = 56A. That's probably around the same draw you have from your current setup but with 3 times the power output.

[jkohman 0]

Ok thanks thats some good info, you guys really know your stuff, I'll put it in stereo and leave it til i can get a better amp. Again thanks you really cleared this stuff up for me.

[Aaron Clinton 2,372]

James has always been quite knowledgeable. Welcome to SSA.

[jkohman 0]

Sorry guys i got one more question, with the amp as stated above it has a level adjuster, its starts out (clockwise) 1, .5(BTL), .3v, 6, 4, and 2, Now im thinking this is to match the hu's preout voltage. correct? And since the hu's preout voltage is 2v, then the level adjuster should be set at 2. Am i correct on this?

[Aaron Clinton 2,372]

There is no law saying you have to match it. Also, there is usually a little voltage drop in the run from the HU to the amplifier.