Help With Amp/Sub

[SxC-32]

Hey peoples

I have a PPI2240 Amp the power ratings are:

60w x 2 @ 4 ohm, 120w x 2 @ 2 ohm, 240w x 1 @ 4 ohm

Would this be a enough to run a MTX 12" 500W Sub?

Thanks

[Fhrx]

Like any subwoofer of this genre it could always use more power but that amp is certainly enough to get it thumping away!

[SxC-32]

thanks heaps man

[Fhrx]

No probs dude.

[Ouch]

you wont have problems running the sub, but its certainly underpowered. Whether or not u'll notice it depends on how picky u n ur ears are. If you want spl, its really fallen short; if u want sq you'll probably be happy for a while but u may find it a bit muddy after a while (or maybe not, depends on how picky u are); or u may be completely happy with the sound...... yes yes, very vague but hope it gives u an idea, cos i kinda had the same thing happening. I eventually had to/am going to change to a more powerful amp

[SxC-32]

im not that picky

my car stereo is not a high priority

ill try it out with the PPI amp and maybe later as your doing now upgrade the amp to a more powerful one

thanks

[SxC-32]

just heard that underpowering any type of speaker will damage it

is this true?

[Fhrx]

Okay, there is a long reply and a short, the short is; No, having little power won't harm your speakers if your sensible with the volume knob.

The long answer is this; In most systems when you hears the speakers ‘distorting’ it’s not the speaker that is struggling, it’ the amp. Speakers are quite simple devices, all they do is reproduce the sound given to them regardless of what that sound may be.

When you ask an amp to do it’s job, it takes a relatively small sound wave and amplifies it before sending that bigger signal to the speakers. If you ask it to do more than it’s capable of (by turning the volume up full blast), it still tries to do what you have asked, but the new amplified sound wave becomes rough and sketchy. This sketchy sound wave jerks the speaker engine around violently and erratically which causes it to heat up and / or break…

Imagine for a second a weight lifter. He is on the bench doing bench presses. With 100 pounds his movement will be nice and smooth and he’ll be almost faultless in his technique. Now you throw on another 300 pounds. He may still just be able to do it, but his arms and legs shake, his breathing becomes irregular and it looks woeful to watch.

You amp does the same, it still attempts to do what you have asked of it, but it sounds dreadful and you get that ‘distortion’ everyone talks about. And here lies the biggest problem – most people assume the speakers are dying, so they go and get a SMALLER amp and as you can imagine from reading above, the problem is just amplified (sorry, couldn’t resist throwing that pun in! ). Anyway, it gets worse.

Now don’t get me wrong, you can fry your speakers with too much power, but there is only two ways – bottoming the voice coil out damaging the speaker internals and believe me, you will hear when you do that. The other way is to thermally overload it – in other words cook it, fry it, burn it – say it how you will.

But the volume will be way louder than your comfortable with I imagine before that happens.

[darkhalf]

if distorting, you are prob just running the preamp and end transistors in the amp at the top end of their limits

isn't a speaker basically a long thin piece of wire coiled? how does having a lower voltage output (even with distorted signal) cause overheating in the speaker coil?

the current consumed by the speaker is constant and the voltage (which is underspecified in this case - hence wattage is lower) so you shouldn't burn out the speaker, the amp would die first

[Fhrx]

I didn’t say low volume distortion hurts speakers. Extreme volume distortion damages them.

When it comes to in-car audio issues, I reply basing my answers on twenty years of installation and journalism (testing etc for magazines) experience rather than scientific formulae. We (installers) run with what does work, not what should in theory…