What Watt? eh?

[womble]

Sorry for the simpleton questions but I'm a newbie, and with all the talk on here of blowing speakers and overheating amps, it seems all to easy and now I'm scared of doing my first gig!

If I have a 1000w amp and 2x 300w RMS speakers does that mean I should only be running my amp at 60% capacity so as not to overload the speakers?

Also - with that setup what kind of room size should I be looking at as a maximum? I'm guessing I'm not going to be doing the MEN Arena without an upgrade... *winky thing*

Ta,
Chris.

[Tom]

Its not all about watts. You need to know the resistance (ohms) of the speakers also.

You say you have 300 watt speakers. Are these 4 or 8 ohms?

Maby if you tell us what amp and speakers you use then people will know your system to give advice. :)

As for power (watts) I would use an amp that is 400 watts rms at either 4 or 8 ohms, depending on what the speakers are and back down the amp. This means you can run the full rms in to the speaker to get the most output.

You will not blow your speakers up like this. The only way you will kill your speakers is if you clip the amp, get a distorted signal in the input and output from the mixer, or if you add too much eq, which would then increase the gain.


As for setups, 300 watts will be fine for most gigs. At the end of the day its not the watts you want to look at, its the efficiency. The higher the max spl, the louder the speaker will be.

If you need output, then just a pair of bass bins and this will increase the overall sound.

To the human ear, 3db is twice a loud, just so you know.

[womble]

I have the Class D SP12SP speakers 300W RMS, max spl is 122dB, 8Ohm impedance.

My amp is actually an AKA 1500w which sends 2x500W @ 8 Ohm (or 2x750W at 4Ohm). So if I plug one speaker into each channel I'm sending 8Ohms to each, I assume, and therefore the power at full whack would be 500w, so do I need to make sure my amp is turned down to about 60% of full power?


I also have a prosound 1000w amp as back up, which I know nothing about and have no manual for so don't know what output it gives at 8ohm, 4ohm or anything. I was thinking of using this to power one Class D CD1220 Bass Bin (of which I have two) at the gigs where a bit more sound is needed. Again, as I'm not sure of the output from the amp (although I know it's a poor one) I'm not sure what level to run this at. The Bass bin has two speakers inside it, would I run one channel into each, or a bridged channel into one and then daisy chain the other across?

[Tom]

With the AKA amp, just turn it down and everything will be ok. Its good to have a little bit of head room.

For the prosound amp, have a look at the maplins website or search for the manual online. I don't think that amp would be good for bass at all. If it was me I would invest in something better as I got a feeling the prosound amp will run out of puff quickly and in fact will make the sound a lot more quiet than what they should.

As for the double bass bin, I reckon it will be wired in parallel so you will only need to feed the cab with one input.


Also, if you do not have one, I would highly recommend you get some kind of crossover.

This will improve the sound of your system a lot. It also means you can turn your speakers up louder providing they don't distort but this is not recommend if you do not know what you are doing, so I would stick to the max rms input, play it safe and everything will be ok. :)

[Bouncy Dancefloor]

by the way, turning the amp volume to number 6 instead of 10, is NOT 60% volume, there is no real way of knowing you are putting out 60%

[womble]

Yeah - I was thinking that, the dB level is exponential or something isn't it?

[rob1963]

Sorry for the simpleton questions but I'm a newbie, and with all the talk on here of blowing speakers and overheating amps, it seems all to easy and now I'm scared of doing my first gig!

If I have a 1000w amp and 2x 300w RMS speakers does that mean I should only be running my amp at 60% capacity so as not to overload the speakers?

Also - with that setup what kind of room size should I be looking at as a maximum? I'm guessing I'm not going to be doing the MEN Arena without an upgrade... *winky thing*

Ta,
Chris.


I have the Class D SP12SP speakers 300W RMS, max spl is 122dB, 8Ohm impedance.

My amp is actually an AKA 1500w which sends 2x500W @ 8 Ohm (or 2x750W at 4Ohm).

Hi Womble,

If your amp puts out 2 x 500 watts rms into 8 ohms, and your speakers are also 8 ohms and rated at 300 watts rms, then there's no way your amp will blow your speakers, even at full volume.

This is because the speaker rating of 300 watts rms means they can take 300 watts at a constant level. However, music is not constant, as it has peaks & troughs. Therefore, your 300 watt rms speakers will ACTUALLY handle up to about 500 watts music power.

Hope this helps.

:)

[nigelwright7557]

You will get many points of view on amps and speaker wattages.

Having worked in an audio shop for a while I have replaced numerous sets of drivers for people who overdrove their speakers.

I am from the school of using a less powerful amp with a higher powered set of speakers. I have yet in 33 years of DJing and playing guitar to blow up a speaker.
I also have never had anyone tell me to turn it up !

The clip LED is on an amp for a purpose so why not use it.

[Tom]

There is a way you can work out how many watts you are sending to your speaker.

You can measure the volts by using a multi meter.

If I am correct, 300 watts is 23 volts. If you can turn the amp up or down to get 23 volts output then that will be the max input for the speaker before you get speaker damage.

[nigelwright7557]

There is a way you can work out how many watts you are sending to your speaker.

You can measure the volts by using a multi meter.

If I am correct, 300 watts is 23 volts. If you can turn the amp up or down to get 23 volts output then that will be the max input for the speaker before you get speaker damage.

That only works for a sine wave.

Music is a complex waveform.

[Tony Scott]

Run the AKA with the potentiometer at Max (8ohm - 500w) and keep it below the clip threshold(red light) and you will be ok...just make sure you keep your mixer and amp out of the red! :)

[Solitaire Events Ltd]

Alternatively, use your common sense, which unfortunately a lot of DJs don't appear to have.

[Excalibur]

I have the Class D SP12SP speakers 300W RMS, max spl is 122dB, 8Ohm impedance.

My amp is actually an AKA 1500w which sends 2x500W @ 8 Ohm (or 2x750W at 4Ohm). So if I plug one speaker into each channel I'm sending 8Ohms to each, I assume, and therefore the power at full whack would be 500w, so do I need to make sure my amp is turned down to about 60% of full power?


I also have a prosound 1000w amp as back up, which I know nothing about and have no manual for so don't know what output it gives at 8ohm, 4ohm or anything. I was thinking of using this to power one Class D CD1220 Bass Bin (of which I have two) at the gigs where a bit more sound is needed. Again, as I'm not sure of the output from the amp (although I know it's a poor one) I'm not sure what level to run this at. The Bass bin has two speakers inside it, would I run one channel into each, or a bridged channel into one and then daisy chain the other across?

The Prosound is for back up purposes only. ;) As our resident technical expert Rob tells you below, don't worry about the tops with that amp. They'll be fine. In a perfect world, a crossover and a second amp at least as big as the first would be ideal. As the 1220's are shown as 4ohms, run one per side on a decent amp. That'll do to be going on with. ;) :D


Hi Womble,

If your amp puts out 2 x 500 watts rms into 8 ohms, and your speakers are also 8 ohms and rated at 300 watts rms, then there's no way your amp will blow your speakers, even at full volume.

This is because the speaker rating of 300 watts rms means they can take 300 watts at a constant level. However, music is not constant, as it has peaks & troughs. Therefore, your 300 watt rms speakers will ACTUALLY handle up to about 500 watts music power.

Hope this helps.

:)
Wow! :eek: Either you've been taking electronics for beginners nightclasses, or reading what I write on here. :D :D



You will get many points of view on amps and speaker wattages.

Having worked in an audio shop for a while I have replaced numerous sets of drivers for people who overdrove their speakers.

I am from the school of using a less powerful amp with a higher powered set of speakers. I have yet in 33 years of DJing and playing guitar to blow up a speaker.I also have never had anyone tell me to turn it up !

The clip LED is on an amp for a purpose so why not use it.
I've blown speakers over twice the rating of the amp, so nothings foolproof Nigel. ;)


Run the AKA with the potentiometer at Max (8ohm - 500w) and keep it below the clip threshold(red light) and you will be ok...just make sure you keep your mixer and amp out of the red! :)
Excellent advice, personally I ease the amp volume off a tad, but that's just me. :D
DON'T run any lights in the red, and you'll be just fine. ;)


Alternatively, use your common sense, which unfortunately a lot of DJs don't appear to have.
Hey mate, who sells that then? I could do with some of that. ;)

[Shakermaker Promotions]

I have never understood the whole OHMS thing. I have never blown any speakers etc but it does worry me to be honest.
If someone could tell me if I am doing some wrong from the following information then that would be cool.

At the moment..If I am doing small to medium sized gigs then I use the JBL JRX 125's with a Peavey CS3000 amp and I set that to about 12 or 2 o'clock on the volume.

If I do bigger gigs or if I am doing my regular nights where I want it a bit more beefier or a fuller sound then I use the same as above but also take the Crown XLS802 amp with a pair of simple Peavey Pro Sub Bass Bins. The amp is set to maximum and I control the volume to them via the Zone or Booth output on the mixer. Yes, I could get a crossover but for some reason I haven't bothered. The whole sound is more fuller. I know the crossover would take the bass away from the JBL's but I like it the way it is and I don't THINK I am doing any harm?

Any help or advice would be great. Cheers.

[Excalibur]

I have never understood the whole OHMS thing. I have never blown any speakers etc but it does worry me to be honest.
If someone could tell me if I am doing some wrong from the following information then that would be cool.

At the moment..If I am doing small to medium sized gigs then I use the JBL JRX 125's with a Peavey CS3000 amp and I set that to about 12 or 2 o'clock on the volume.

If I do bigger gigs or if I am doing my regular nights where I want it a bit more beefier or a fuller sound then I use the same as above but also take the Crown XLS802 amp with a pair of simple Peavey Pro Sub Bass Bins. The amp is set to maximum and I control the volume to them via the Zone or Booth output on the mixer. Yes, I could get a crossover but for some reason I haven't bothered. The whole sound is more fuller. I know the crossover would take the bass away from the JBL's but I like it the way it is and I don't THINK I am doing any harm?

Any help or advice would be great. Cheers.
You're not doing anything wrong. It's a viable way of achieving what you want. When I want a similar result, I use a second pair of full range cabs ( which have twin 15" drivers in, so they pass as subs in effect). It's easy and it works, which is I guess why you do it the way you do.
I'd suggest you try borrowing a crossover, and have a play with it. Its surprising how altering the controls on it can change things.

[Tom]

That only works for a sine wave.

Music is a complex waveform.


Yes, that is true, but Sine waves are louder than music, so if you can find out how many volts you are sending to the cab, then you know you will be safe with the max rms input and not fry a driver.

[Tony Scott]

......Sine waves are louder than music.....

Oh yes, get a nice sine wave sweep from 200hz to 30hz at around 8kW and watch the windows flex!! :D

[Tom]

Oh yes, get a nice sine wave sweep from 200hz to 30hz at around 8kW and watch the windows flex!! :D

:lol:

Bass....how low can you go. lol

[rob1963]

Hi Womble,

If your amp puts out 2 x 500 watts rms into 8 ohms, and your speakers are also 8 ohms and rated at 300 watts rms, then there's no way your amp will blow your speakers, even at full volume.

This is because the speaker rating of 300 watts rms means they can take 300 watts at a constant level. However, music is not constant, as it has peaks & troughs. Therefore, your 300 watt rms speakers will ACTUALLY handle up to about 500 watts music power.

Hope this helps.

:)


Wow! :eek: Either you've been taking electronics for beginners nightclasses, or reading what I write on here. :D :D

...or speaking to my brother, who happens to be an electronics engineer ;)

[Babybob]

Is Nigel your brother then???;) :p

[DJMaxG]

It depends entirely on the Amplifiers Ohms setting, and how you run it.

If the Amplifier and speakers are BOTH 8 Ohms, then you would use a 300 watt amp with 300 watt speakers.

However, If the speakers are 8 ohms, and the amp is running at 4 Ohms Stereo, then you would use a 1300 watt @ 4 ohms amp.


Alternatively, use your common sense, which unfortunately a lot of DJs don't appear to have.

I know exactly what you mean!

I have seen Club DJs go in the RED before.