Help with sub and amp

[puss puss]

Hey, this random girl of msn is selling me a amp (lol she didnt even kno what it was) a kenwood jobbie 2/3/4channel i think. for 25 notes o.0!

Well i read it up, and it could put out about 220watt rated, if i bridged it to one channel.

The jbl gt4 sub i think it is can handle about 250 watts rated i been told, so all sounds good atm.

Yet the amp puts out 220 watt at 2ohms i belive it is.

But the sub wants 250watts are 4ohms!

so would this amp be able to run this sub lol? am a little bit confussled with the whole Ohms thing. I know that it is resistance but am not sure if it will damage either the sub or the amp.

Thanks for any replys Nathaniel :thumb:

[Jack]

Can the amp handle 4Ohm resistance? Often find they can do multi resistance (but it'll be a different power output); may also depend on how the sub is wired up to the amp.

If the amp can handle the higher resistance it'll just output a different power; if it can't then it could damage the amp or sub. A kid on the local kroooze forum recently broke his amp by apparently trying to run a 4Ohm sub on a 1Ohm amp.

Have you got a model number for the amp so we can look up manuals for specific specs?

[bump]

IIRC if the amp can handle a 4ohm load then the power output will halve.

[puss puss]

urgh if so what amp would u say i should get for that sub it is a jbl gt4 12inch sub =P

[philly]

anything really with atleast 600 watt rms or even max power

if you manage to get a jbl gt0 amp rated at either 600 and 800 it will make the best difference.

[Jack]

NO! 600WRMS is far too much for a 250WRMS sub!

GT4-12 is 250WRMS/1000WPMPO @ 4Ohms. Ignore the max power output figure, the RMS is the important one (also shows how limp JBL stuff is if its only 250W continuous power, but thats beside the point lol)

You need an amp that can match those figures - The Alpine MRV-T320 can be bridged to mono and puts out 1x 240WRMS @ 4Ohms when running on 14.4V (i.e. with the engine running).

[Lucky Luke!]

One of the most common reasons that subs blow is not through being overpowered but by being underpowered.

If you have a 250w rms sub with a 200w rms amp then most people think that you cant blow the sub cause the power rating is higher so they crank the amp right to the max. in actual fact this is what blows the sub, when you crank an amp over about 3/4 the amp starts to distort, its this distortion that leads to the overall destruction of the sub.

i would personally recommend about a 280w rms amp to run the 250w rms sub just dont turn the amp over 3/4.

[focus_neil]

Im with Luke on this one, alwys get an amp thats slightly more powerfull than the sub. This way the amp doesnt need to work mega hard to get decent quality :)

[puss puss]

ok thanks for all ya help, ill jus use that amp to run my front speakers den hehe, ill go with jack and get that amp :)

[mikey14sr]

All multi channel kenwood amps are 4ohm stable, but the one you describe will only put out about 100w rms bridged into a 4ohm load, the 220 into 2ohms qouted will be a peak figure.
I have a little 529 which says 250watts on the badge, but the only way to get that out of it is into a 2ohm load when bridged (and turned right up), In stereo mode it can just about manage 2x70w rms @4ohms.

[puss puss]

ahhh right looks like ill use this to drive some front speakers den, say no to 6 by 9s lol

[L14MNP]

NO! 600WRMS is far too much for a 250WRMS sub!

WTF! No it's not lol

ALWAYS get a more powerful amp than sub. Always.

It makes a lot more sense to have say an 800wrms monoblock amp running a singular 300wrms sub, at half gain (or below) than having say a 300wrms amp and a 300wrms sub with the amp on full gain constantly, this is bad news for the amp and the sub would run a lot better if the amp powering it were not straining to supply the power!

One of the biggest problems people make is buying underpowered amps IMO

[puss puss]

hmmm i see where you goin with this l14 makes sense

i supose jack is just saying that incase i turned its gain up to the max n blew the sub :P

[Jack]

A 300WRMS amp won't "strain" to reach 300W, hence why its rated at 300WRMS! Put the gain up to max and the amp will be pushing towards its PMPO figures, not its RMS figures. By all means get an amp thats more powerful than the sub and adjust the gain to match, but not excessively so.

My alpine amp runs about 75% gain to my sub and has never had any issues. Aside from my crappy wiring lmfao

[puss puss]

hehe yea i see what ya saying dude, so is there any decent sub n amp bundle out there now a dayz that a student can afford?

i brought that amp, i just got to get a head unit now lol!

[L14MNP]

I love PMPO figures lol

I wouldn't personally run 75% gain on my Soundstream Van Gogh (not the cheap looking $hit with the spider emblem!) 1000wrms 4ch which powers my focal utopia two ways and focal utopia 13" sub - but if you've had no issues then good stuff mate :) What comps and sub are your running Jack?

Can't beat my Novas ICE, standard dash speakers and a Sony MD HU (had to blow the dust off that one) lol

We can debate forever, the 'will it/wont it' of subs and amps, but consider any future upgrade you may do, it's a lot easier and cheaper buying a new sub than amp! If you 'over budget' on your amp you can improve on your sub and your fronts - if they are powered without buying another amp

puss puss, what kind of **** do you listen to dude? It makes finding the suitable amp/sub or package all the easier :)

[puss puss]

err well personally i listen to all types of music o.0, but i would say mostly dnb rip hop rap mc r n b dance, basicly things like that :D

[Jack]

What comps and sub are your running Jack?
Just cheap n' cheerful stuff really, dunno what the comps are - I assume they're std fitment. The JL 10W3 runs off an Alpine MRD M605, factory test chart shows it with RMS of something around 340WRMS iirc even though its only listed as 300WRMS lol

Both ebay specials which came up at the right time and right price, but work well together so I'm happy. Given the time and money I'd be temped to buy a similar setup for the nova, but perhaps more powerful kit :D

[bump]

I've gone for a Vibe Active unit. Not the cheapest but puts out a good solid low end and the amp is perfectly matched to the sub.

[Lucky Luke!]

A 300WRMS amp won't "strain" to reach 300W, hence why its rated at 300WRMS! Put the gain up to max and the amp will be pushing towards its PMPO figures, not its RMS figures.

RMS figures on a amp are at around 3/4's of the gain, past that is going up to its Max power output, thats when it starts to distort.

when it comes to audio, cheap stuff doesnt last anywhere near as long, we had one guy buy 3 12" JBL subs cos he kept blowing them, that money would have bought a nice 12" JL W3 which wouldn't have blown and sounded much nicer.

Dont skimp on quality if you cant afford decent stuff right away, save up until you can, you will be glad you did in the long run.

I would recommend a JL 12" W1 (it has W3 technology but with a W0 price tag)

and a JL A1400 monoblock amp.