Ohms question

[pinhedgtr]

I have a Makie 1400i power amp for my PA system, I was wondering, since there is no ohms selector (like on m guitar amp) does the amp just automatically detect what ohms my speakers are? Hope that makes since.

B

[DrJones]

Originally Posted by pinhedgtr

I have a Makie 1400i power amp for my PA system, I was wondering, since there is no ohms selector (like on m guitar amp) does the amp just automatically detect what ohms my speakers are? Hope that makes since.

B

It is rated @ 850w@8ohms
1260w@4ohms BRIDGED

Depends on your output wiring

[warble]

Originally Posted by pinhedgtr

I have a Makie 1400i power amp for my PA system, I was wondering, since there is no ohms selector (like on m guitar amp) does the amp just automatically detect what ohms my speakers are? Hope that makes since.

B

Yes.

If you have two 8 ohm speakers, the amp will know this and power accordingly. I wouldn't go below 4 ohms with the amp - or really any amp. I know there are amps that have pretty good protection for driving loads like 2 ohms, but I'd never do it myself. Always 4-8 ohms (but check your amps documentation FIRST).

[littledog]

Does water "know" to flow downhill? Not really - it just is obeying the laws of nature. Same with your amp. It doesn't "know" anything about ohms - it just follows the laws of electricity.

Think of a large tank of water sitting on a table. We'll call that our amp. You poke a small hole into the bottom (we'll call it an 8 ohm hole), and a thin jet of water starts to squirt out. We notice it shoots out about 12 inches from the bottom of the tank. Now you make the hole twice as big (we'll call that a 4 ohm hole). A thicker stream of water flows out, but it only shoots about six inches from the bottom of the tank. To get the thicker stream/bigger hole to go 12 inches, we need a bigger tank (amp) with more water in it. (More watts).

I'm not an electrical engineer - so I my analogy may be a little screwed up. I welcome corrections from any real tech guys out there. But I think it basically illustrates the point that a tank of water doesn't "know" anything... it's just a tank of water subjected to the forces of gravity.

[Farview]

Generally, solid state amps are not picky about the ohm load (above the lowest rated load) Tube amps however, have to be matched.

[pinhedgtr]

Cool thanks for your help guys, I have been wondering about this for a while now and the documentation did'nt say anything about it. The reason I was wondering is that I have one of my 1400i's running an 8ohm sub and it does'nt sound like it's pushing it very hard (at least compared to the amp pushing the 4 ohm mains).

Thanks,
B

[littledog]

Just also remember that an 8 ohm speaker means that it works best at 8 ohms. It doesn't mean that they magically convert any resistance to 8 ohms. If you hook up two of them in series, they will be running at 4 ohms.

[pinhedgtr]

Yeah, good point. Right now I am only using 1 sub.

[Farview]

It also takes much more power to reproduce low end than it does mids and highs.

[$a1Ty]

run that amp in bridged mode, that'll give the sub more guts, careful though depending on the power rating of the sub

hell i've ran an australian monitor 1k2 amp in bridged mode thats about 1000W through a bose 502 sub hehehehe

[littledog]

Unless you are cranking the amp to ten and sending a highly compressed signal, I wouldn't worry about the power rating of the sub too much. More speakers are damaged from underpowering them than overpowering them.

What happens is, in an effort to squeeze every bit of loudness out of an underpowered amp, you produce clipped wave forms, which are extremely hard on the speaker - because you have all these flat extended periods of maximum volume.

An "overpowered" signal going to an amp may have very high transient peaks, but that is the point - they are transients which are extremely short in duration and will not damage the speakers in most cases.

[pinhedgtr]

Originally Posted by littledog

Unless you are cranking the amp to ten and sending a highly compressed signal, I wouldn't worry about the power rating of the sub too much. More speakers are damaged from underpowering them than overpowering them.

That's good to know, I thought I read somewhere that its okay to put about twice as much power than a speakers RMS rating. So if the speaker is rated at 300 watts then 600 watts of power won't hurt it. I think my sub is rated at 300 watts, and if I put the amp in bridge mode then it will be pushing 1000 watts at 8 ohms. I think I'll try this and hopefully I won't blow up my speaker

[gecko zzed]

Originally Posted by $a1Ty

run that amp in bridged mode, that'll give the sub more guts, careful though depending on the power rating of the sub

hell i've ran an australian monitor 1k2 amp in bridged mode thats about 1000W through a bose 502 sub hehehehe

i regularly run a similar aussie monitor into a pair of 50watt speakers, no worries!

[$a1Ty]

my aim is to destroy that bose 502 sub, if anyone has used them you'll know what i'm talking about they are bootch

[pinhedgtr]

Put it in bridged mode last night, now that thing pounds! Thanks!

B