Ohms my god

[cara]

reading through the ohms thread i'm still none the wiser can anyone explain it in s.i.m.p.l.e. terms please? pretty please

here's my set up:

a yamaha emx5000 powered mixer with a spec of 500W+500W/4ohms
325W+325W/8ohms 1000W/8ohms bridge

i have 2 x 350w class d tops & 2 x 500w class d bass bins

so if i use my 2 tops and 2 bass bins what power output would i be getting from my mixer? and what ohms would it be?

and if i just used the 350w tops what power output would i be getting? and what ohms would it be?

if you could try and keep your answers short and sweet guys so i can grasp it in simple terms

i feel if i can understand what my setup is producing then i may be able to get what ohms are.

merci:beer1: :beer1:

[mikeee]

S.I.M.P.L.E.

I assume your speakers are 8 ohm cabs??

Top cab on it's own = 8 ohms = 350w from mixer (Speaker handling 350w)

Top cab linked to bass cab = 4 ohms = 500w from mixer (Speaker handling 350w + 500w = 850w).

Other than the fact the amps may be over working a little bit at the 4 ohm level (amp delivers 500w, speakers handle 850w), if your careful you should not have any major problems on a "normal" function. If you do bigger function that need all the power you can muster, them the amps might start to get a bit warm :). In this instance I would probably suggest using the mixer / amp to drive the top cabs and a second amp (500w + 500w into 8 ohms) to drive the bass bins. IMHO

[spin mobile disco]

Ohms = resistance
Thinks of a pipe carrying water the smaller the pipe is the more resistance so the harder a pump has to work to push water through. The pump is your amplifier.
Your amp can only push so much power out like the water pump. When the ohms are high ( 8 ohms for example) it can only push less water through the pipes. So you get lower power hence why at 8 ohms you get less power from your amp than at 4 ohms.
At 4 ohms imagine the pipes are wider and it can now push more volume of water through so more gets through than at 8 ohms.

Now if you link 2 speakers togther in parallel for example 2 8ohm speakers. It becomes a 4 ohm load. Reason is there are now twice the 'pipes to take the volume of water. So you can now get the higher volume from the amplifier.

Most amplifiers have 2 or three modes of operation 2 4 or 8 ohms depending on the type of amp. Most amplifiers prefer to run at 8 ohms and 4 ohms with 2 ohms being really a short term thing.

Hope this helps.

[sleah]

SOther than the fact the amps may be over working a little bit at the 4 ohm level (amp delivers 500w, speakers handle 850w

Not strictly true. The amp won't work any harder if the speakers are 850W or 500W (assuming both 4ohm), it's the operator who's tempted to push them that little harder to get the max out of the amp:rolleyes: , so the amp will give up before anything happens to the speakers.

However if you have 300W worth of speakers on said 500W amp, you won't be pushing the amp quite so hard, if you do then the speakers will catch fire before the amp gets upset.

This is why I advocate having speakers rated the same or higher than the amp. You can see when a (decent) amp is clipping, and it may start to sound odd, so you can turn it down a little before it overheats, but it will probably be too late when a speaker tells you it's unhappy....i.e. when a speakers sounds bad - it's knackered.

At the end of the day, regardless of ratings, plug it all in, turn it up slowly, and if it sounds good and the amp isn't exesively hot, then chances are your OK. If at any stage the amp gets very hot or sound is distorted or simply doesn't sound as clean as it did at lower volume, then there is something wrong and you need to turn it down quick!

[mikeee]

The original post said Keep It Simple. It is very easy to start over driving if it don't sound as loud as it should, hence the amp's might get a bit warm :)

The other point is to get the best sound (as close as) the amp should be more powerful than the speakers. I personal use a QSC RMX 2450 in to a pair of Carlsbro Beta 115's, this gives 500w into a 300w speaker. You are only, under normal usage going to get close to 500w on the peaks, and normal good quality speakers will handle that without breaking a sweat.

[Andy Westcott]

The simple figures:
Your system will develop a maximum of around 325 watts a side of undistorted sound, and you amplifier will be operating into a nice, safe and reliable 8 ohms.

Now the BUT bit:
This assumes the cabinets are 8 ohms.
It also assumes there is a crossover working to split the low frequencies from the high, as otherwise the bass units & the tops will be in parallel.

Also we must remember that loudspeakers, especially ported bass bins, only exhibit the minimum 8 ohms impedance at port resonance, and will have a higher reading than this above & below, reducing the power the amp can push into them.

It's getting complicated now, which you didn't want! :)

[Excalibur]

The simple figures:
Your system will develop a maximum of around 325 watts a side of undistorted sound, and you amplifier will be operating into a nice, safe and reliable 8 ohms.

Now the BUT bit:
This assumes the cabinets are 8 ohms.
It also assumes there is a crossover working to split the low frequencies from the high, as otherwise the bass units & the tops will be in parallel.

Also we must remember that loudspeakers, especially ported bass bins, only exhibit the minimum 8 ohms impedance at port resonance, and will have a higher reading than this above & below, reducing the power the amp can push into them.

It's getting complicated now, which you didn't want! :)


Agreed totally, thank you for posting that, I have got weary of doing that, and then dodging the missiles! There is however, a but if......................................

But if you wish to go for maximum power, you could feed the tops directly from the amp, and run your subs in parallel, ( Plugged into the normal sub input, NOT the high out), thus giving 4ohms impedance, and
250w per cab, which is also an acceptable figure. I am not saying I recommend this, just that it is another option.