Ohms?????!!!!!

[wolfracepunto]

On an amp im looking at it says-
200W RMS @4ohms mono
300W RMS @2ohms mono
500W RMS @1ohm mono

what does this mean? would i have to do anything if i wanted it to run at 500W RMS?

also reckon kenwood amps any good connected to a pioneer sub?

EVERYONE- SPRAY YOUR PUNTOS BLACK

 

[arseofbox]

THe mono bit means its thru one channel only.
The RMS Power figure in Watts is the average power the amp puts out.
The Impedence (the 4,2 or 1 ohm figure) is a measure of the output resistance of the amp.

Yu can get subs in 3 main impedances, 1 Ohm, 2 Ohm and 4 Ohm. Amps are usually rated to 4 Ohm or 2 Ohm, but some are 1 Ohm stable.
Ideally speaker impedences and amp impedences should be matched, to get the most power out.

What the info means is that running that amp with a 4Ohm speaker will oitput 200W, a 2Ohm ouptuts 300W and a 1Ohm outputs 500W

Best bet is to buy a speaker with a max power over the maximum power yu want to output, eg if yu want to max out at 500W, get a 700W sub. This gives some overhead in case it all goes fully pearshaped.


Tom (AofB)

95 Cinq Sporting - Rattly GrpN Catback Exhaust, <font color="black">Buckets</font id="black"> and 3pt Harnesses,Sexy VW styleé dials (that look great, but dont work!! D)), 10" Sub and 6x9's, ETech Wing. Lots of Dirt!
1242cc Engine to go in soon, boot delock soon, K+N still in garage!

 

[chrisunoman]

The ohm stuff that you can see on the amp is telling you the power it would produce using different ways of wiring up your subs.

For example, if you have a 4 ohm sub (the norm) with two voice coils, and wire up the voice coils to run in parallel, then the sub will now be 2 ohm. If you have two of these subs, and you wire them both in parallel as well, the amp load will then be 1 ohm.

That sounds like a decent amp as well, if it will run 500w rms at 1 ohm

 

[wolfracepunto]

thanks for the info- so it depends on the sub i buy.....

that amp is a kenwood mono for 155 quid. the sub i want says
'Dual 4-ohm voice coils: 2 or 8 ohm'
does this mean it will run at 2 ohm?

sorry if im being really thick........:I

EVERYONE- SPRAY YOUR PUNTOS BLACK

 

[chrisunoman]

yep, if you wire the voice coils in parallel, it will run at 2 ohm

youre not being thick dude, the amount of people i know who dont think that there are different configurations of running speakers is unbelieveable

 

[wolfracepunto]

lol cheers

so do u reckon 300W RMS would sound ok?
are the 1 ohm subs pretty expensive then?

thanks again

EVERYONE- SPRAY YOUR PUNTOS BLACK

 

[chrisunoman]

Yeh a 300w RMS sub would sound great.

To get a 1 ohm sub, you'd wire the voice coils of a 2 ohm twin voice coil sub in parallel.

2 ohm stable subs are a bit more expensive than 4 ohm ones and theres not as big a choice

Because your running the sub at a lower impedence, the amp will be workin a bit harder too

 

[wolfracepunto]

Sorry to bring this old thread back up, but im confused again

In about the last week ive changed my mind on loads of sub/amp packages I might get. I wanted a Kicker sub at first but to make things cheaper ive picked these-

Kenwood KAC-8152D Mono Amp
Rated power (4 ohm, 20 ~ 200 Hz, 0.5% THD) @ 14,4V : 300W RMS
Rated power (2 ohm, 100Hz, 0,9% THD) @ 14,4V : 550W RMS
Maximum output power @ 14,4V : 1100W

Alpine SWR-1222D - 12" 1500W subwoofer
Dual 2-ohm voice coils
Power handling: 200-500 watts RMS
Peak power: 1,500 watts

Its got those dual 2-ohm things which I still dont understand. Will that amp power the sub to 550W RMS?

If ive got that completely wrong can anyone recommend another package around 320quid and 500W RMS?

Thanks

 

[dave]

ohms is wiered 2+2 = 1 with ohms
http://www.the12volt.com/ohm/ohmslaw.asp

 

[wolfracepunto]

Does that mean I need an amp that is 1ohm stable :bang: lol

 

[chrisunoman]

Does that mean I need an amp that is 1ohm stable

Yes unfortunately

Or you could run the sub differently at 4 ohms.

 

[The Negotiator]

ohms is wiered 2+2 = 1 with ohms
http://www.the12volt.com/ohm/ohmslaw.asp

Dave, when working out total resistance (which ohms is a measure of) you use ohms law, V = IR (Voltage = current X resistance) and rearrange.

If two resistances are in series, the equation is: Rtotal = R1 + R2

If two resistances are in parallel, the equation changes to:

1/Rtotal = 1/R1 + 1/R2

If you have 3 resistances, series is Rtotal = R1+R2+R3 and so on.

Hence, if you wire in parallel a few resistances, the total resistance drops. Think of this in a way of water in pipes.

If you have one pipe with 2 valves half closed down it, the flow will be more restricted than if you have 2 separate pipes with a single valve in each half closed since you're allowing more paths for the water to flow. Now change water flow to electrons and voila

 

[chrisunoman]

Here we go:

http://www.caraudiodirect.co.uk/pro...d=4114&cadid=722c4344c3d615f216b2e21e9aaaafb6

The reason your amp wouldnt run the sub at 2ohm was because its a mono amp, and to run the sub at 2ohm you need to give each voice coil its own channel.

This amp would give each voice coil 250w rms at 2ohm and is Kenwood like you were after in the first place.

Hope this helps.

 

[wolfracepunto]

That does help, thanks again Chris.

With that amp (only 129.99 @ Caraudiosecurity ) it will power the sub at 500W RMS.

So how would it be wired- as in where each wire connects to. Ive seen pictures of both the sub and amp and they have 4 terminals, is it a case of one wire from each?

 

[chrisunoman]

Yeah thats right, one wire from each of the terminals, wiring each voice coil off its own channel.

Glad i can be of service

 

[wolfracepunto]

No doubt I will change my mind again but at least I know how the dual voice coils work now.