4 ohm Or 2 ohm? Trying To Weigh The Pros and Cons...

dako · Post by **dako** » Mon Sep 22, 2008 9:54 pm

I'm strongly considering ditching my Alpine Type-Rs and going with a pair of RSDC124s. Here's my question, If I get the RSDC124s and wire them at 8 ohms each (sealed box w/separate chambers and terminals for each sub), and then run each sub to a set of inputs on my Tantrum 1200.1, the amp will see a final load of 4 ohms, correct? I know the amp terminals are wired in parallel, but I don't want to second guess anything and cause a disaster.

Also, does anyone have an opinion on a 4 ohm load vs. a 2 ohm load? I've heard it said that a 4 ohm load will "allow for better SQ" and create less of a burden on the electrical system. I'm not really sure how ohms play into sound quality reproduction though. Since I'm trying to tailor my system strictly for SQ, this would be a huge bonus if there were some validity behind it. Right now I feel like I'm unnecessarily taxing the amp with a 2 ohm load, especially when it'll make the same power at 2 or 4 ohms.

So if two RSDC124s to the amp will yield a total 4 ohm load, I'd be looking at around 650rms to each sub, putting them right there in a pretty comfortable range. Gahh, it's almost 2am...No wonder I can't figure this out on my own. Thanks in advance for any help and advice. I just got a set of RSD65CS comps and a Tantrum 500.2 to run them, so going with the RSDC124s seems like the next logical progression in my setup, especially with all the good reviews they seem to be getting everywhere I read about them.

fordtough1 · Post by **fordtough1** » Tue Sep 23, 2008 2:46 am

I don't know on the Tantrum amp if it will make a huge difference on electrical draw or not. When I was running a Ti 1000.2 (big A/B class amp) at 2 ohms, it was hard as hell on my electrical system. I'm now running a Xenon 1200.1(big class D) at 2 ohms, and my electrical system has thanked me for it.

I don't know about the sound quality difference though...

dako · Post by **dako** » Tue Sep 23, 2008 6:09 am

That's what I was kind of figuring, since the Tantrum is technically a Class-D (or T) amp. I only get headlight dimming when the volume is to the point of ridiculous and I usually don't flog the system too badly, just a little here and there.

Hopefully someone can chime in on any SQ differences that might be perceptible. Or would it really even matter since we're talking Class-D amplification?

fordtough1 · Post by **fordtough1** » Tue Sep 23, 2008 7:10 am

Yeah I don't know. Honestly I couldn't tell the difference sq wise between the A/B, and the D class on the subs, but then again my hearing isn't so good after years of working in an auto shop.

Post by **stipud** » Tue Sep 23, 2008 7:58 am

It will sound worse, the amp will get hotter, and you won't get a noticeable increase in power. With your amp, stick to 4 ohms.

scorpio86 · Post by **scorpio86** » Tue Sep 23, 2008 9:49 am

then what about 4 vs 8 ohm.. same thing.. ?? les power.. but less current demand and more headroom..??

Post by **stipud** » Tue Sep 23, 2008 9:59 am

Half the power... doubt you could hear a difference in SQ (better on paper though).

maka78 · Post by **maka78** » Tue Sep 23, 2008 10:07 am

So are you saying that since I'm running 2 TI12D elites parallel at 1 Ohm on 1 amp @ 2400w, I'm getting horrible SQ compared to running, let's say 4 amps @ 4 ohms/amp @ 600w/amp? or 2 amps @ 2 ohms/amp @ 1200w/amp?

Post by **stipud** » Tue Sep 23, 2008 10:33 am

maka78 wrote:So are you saying that since I'm running 2 TI12D elites parallel at 1 Ohm on 1 amp @ 2400w, I'm getting horrible SQ compared to running, let's say 4 amps @ 4 ohms/amp @ 600w/amp? or 2 amps @ 2 ohms/amp @ 1200w/amp?

No. FOR HIS AMP, 4 ohm load is the best. It's rated to produce its full power at 4 ohms, so a 2 ohm load would require it to restrict itself, making the amp chug back lots of power only to produce more heat with it, and very little extra power.

Theoretically though, higher impedances do offer more control over the speaker, so they are generally considered to sound better. You might find your subwoofers would play "tighter" getting the same power at a higher impedance.

Post by **fuzzysnuggleduck** » Tue Sep 23, 2008 11:00 am

Pro audio gear tends to run at 8ohms if that means anything to the SQ argument.

bretti_kivi · Post by **bretti_kivi** » Tue Sep 23, 2008 11:19 am

... but again, with less power, but tendentially better efficiency. Less heat.
which is why I'm going to see whether the 8ohms off of a QX180.2 is enough, it might be, but theory and practice are two sides of the same coin. 25W per side for Midbass ain't much, especially if there's 500W on the sub.

There's always going to be a load for which an amp is designed. D is more efficient (80%) as opposed to the 50% of A/B, but D involves the PWM of the signal (i.e you create a signal and provide it for 80% of the time to get an 80% signal) rather than a different output voltage. Depending on the frequency and design, you might get interference (as reported in some cases on early Alpine PDX 4.100s). Since a sub really will ignore such high frequency information....

Hope this helps.

Bret

KHPower · Post by **KHPower** » Tue Sep 23, 2008 11:29 am

I always heard that the 3 ohm subs and speakers are best suited for sound quality and I have always wondered about ohm load vs SQ as well.

I guess alot of it would have to do with the amp

dako · Post by **dako** » Tue Sep 23, 2008 11:38 am

Thanks for all the info so far guys. I just placed an order for a set of RSDc 12's and will be wiring them for a 4 ohm final load.

KHPower · Post by **KHPower** » Tue Sep 23, 2008 12:17 pm

dako wrote:Thanks for all the info so far guys. I just placed an order for a set of RSDc 12's and will be wiring them for a 4 ohm final load.

You should be quite happy with em

I still have a BNIB one that I am trying to figure out what to do with it.

cojones · Post by **cojones** » Wed Sep 24, 2008 6:45 am

The impeadence in SQ comes from Dampening. Dampening is better at higher impeadences. That is why interior speakers are 4ohms rather then 2. Dampening is the speakers ability to stop after a electrical pules. Sorry I saw this post late.

ferrariboy150 · Post by **ferrariboy150** » Wed Sep 24, 2008 11:30 am

if the rsdc's sound good ported ill take that off your hands khpower

KHPower · Post by **KHPower** » Wed Sep 24, 2008 11:31 am

ferrariboy150 wrote:if the rsdc's sound good ported ill take that off your hands khpower

Send me a PM