I've noticed that in previous posts that Chris says that you are best to have speakers MORE powerfull then amplifiers which you can do but it's not that safe.


I've always beeing told that the goldern rule for sound engineers is that your amplifier must be MORE powerfull then your speakers to get the best possible sound ie: Clean undistored sound and you have a much lower risk driving your speakers in to clipping. I believe in this.

I can support what I say, there is a nice article here on the JBLpro website http://www.jblpro.com/pub/technote/lowpower.pdf or http://www.jblpro.com/pages/general_faq.htm about having amplifiers more powerfull then speakers.

For an example. If you have a speaker rated at 8ohms and power output of 300watts RMS then you need to have an amplifier which is rated at 600w at 8ohms to get the best possible clean sound. Believe me you can hear the difference! I know this an expensive way but i've always been told it's the proper way. I have never had any problems when doing this or any such clipping!

Hope this helps some people.

Thanks,

Shaun Mintern

If it were possible to deliver 600Watts safely into a 300W speaker then no manufacturers would be building speakers above 300Watts. we'd all be happily running our 100W cabs from 1000W amplifiers .

I'm currently repairing a Peavey Black widow...the owner had the same idea until last night, when he literally blew it up.

For anybody who wants to try this...then i do some extremely competitive speaker repairs .

What you have basically said is that it is possible to deliver 600 Watts RMS from a 300 Watt RMS Loudspeaker

Like its also a good idea to draw 30 Amps from a 13 Amp socket!. Just because it's possible... doesn't make it safe or advisable.

Yes having a 3kw sound system and using it to deliver 700 Watts is a good idea and it will sound better since you'll only be using it at 25% of its design rating, so having a LARGER system than you need is good advice. But it's another matter entirely if you plug a 500W loudspeaker into a 1.5kw Amplifier then attempt to ask the speaker to produce 1500W.

However contact your loudspeaker manufacturer and ask them if they will cover your warranty if you connect an amplifier rated twice that of your loudspeaker.

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If you have a speaker rated at 8ohms and power output of 300watts RMS then you need to have an amplifier which is rated at 600w

Hi,

That sound's extra dodgy to me, no offense, but driving your speakers with a higher amp output is abit risky. It should be ok if you get the output of the amp at the right level, but if you go over it the speakers won't last long.

I think this is where the confusion arises, you wouldn't necessarily feed the speakers all the amp had to offer, it about having amplifiaction that isn't busting a gut sending nasties down the signal path.

If you've got a nice big beefier amp crusing along chances are you speakers will be singing and the bass will sound nice and full.

I've no problem with well matched amps and speakers. The problems arise from underpowered amplifiers that aren't up to the job being put upon . A short sudden clip can damge tweeters very quickly. If a big amp was pushing speakers too hard you'd probaly have enough time to turn it down.

Thanks for your replies here. Chris is pointing out the safe side here I suppose there are lots of arguements to this case.

Having an underpowerd amp for speakers makes the amp work very hard. Which causes a lot of heat build up in the mosfet transitors.

I see what you mean. It getting a lil complicated now. Speakers only use a little power as much of the power is lost in heat, crossover and cable so the speaker only gets small power amounts.

Thanks for your help.

Shaun

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The problems arise from underpowered amplifiers that aren't up to the job being put upon

However, problems also arise from underpowered speakers running on high power amps! Anyway, driving a 1k speaker is going to put almost exactly the same strain on the amp as driving a 500 watt speaker.

There are two schools of thought on this as we have seen. I personally drive my speakers around the same RMS value as the amps. ive never had any problems doing this. If you know what you are doing then using more powerful amps will be fine (most of the time) i would certainly hope you ouldnt greatly overpower a speaker without a limiter in teh chain somewhere.
It also depends what speakers you are driving - and what frequencies you are using - for example, an eminence delta 12", which is a 400 watt 12" pressed steel speaker - pretty standard - will happily provide 400 wattts RMS of 60Hz bass. However if you use it for midrange - say over 300Hz then its gonna happily sing along all night at 600watts or so - however i would still rather be on the safe side. Also, compression drivers are much less tolerant to higher power than bass cones.

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much of the power is lost in heat, crossover and cable

if you are using an active / decent passive crossovers and suitable cable then the power loss here will be minimal (almost non existant) some power is lost as heat tho.

Happy arguing
Regards
Steve

For some clarification at this point, what the JBL download was effectively saying, is that an amp rated lower than the speakers, is ok....

...Until, you drive the amplifier really hard (EG: whack the mixer Master output to maximum, turn up the BASS EQ to +15db...etc..etc..) at which point you could make the amp distort, or clip...

Even though this clipping, or distortion would be hitting the speakers at a WATTAGE that the speakers could normally handle, the clipping (and its associated distortion), could well have undesirable effects on the clarity/purity of the signal.

This is why I would recommend a limiter/compressor to anyone finding themselves in a situation of having to show concern for their speakers....which is all of us, right? Well, its those of us with more powerfuls amps, than speakers, or those with less amp output wattage than their speakers, but frequently finding themselves "pushing" the mixer to amp signals/levels.

[/QUOTE]
For an example. If you have a speaker rated at 8ohms and power output of 300watts RMS then you need to have an amplifier which is rated at 600w at 8ohms to get the best possible clean sound

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Shaun: I think the confusion arises due to the the way manufactuers label the specs on their cabs. Most pro speakers will give you two ratings for their speakers: RMS (also called continuous) & Program (Also called music). Prog rating is double the RMS rating. Hence a 300watt RMS speaker is also rated 600watts prog and can be fed 600watts of amp power. Most manufactures recommend this. e.g JBL Sound Factor series is rated 250watts RMS, 500watts Prog. JBL recommend 500watts of amp power for that cab. Peavey Hisys 2RX is rated 500watts RMS, 1000watts Prog. Peavey recommends 1000watts of amp power for the speaker. RMS rating is usually calculated using a continuous sine wave/pink noise signal which is far too demanding on speakers that a music signal. Therefore a prog rating is derived to allow for proper matching of amp power to speaker power.

If a big amp was pushing speakers too hard you'd probaly have enough time to turn it down.[QUOTE]

Martin:
Unless you are quicker than the speed of electricity you will damage the speakers if you exceed their limits, before you even realise.

[/QUOTE]
For an example. If you have a speaker rated at 8ohms and power output of 300watts RMS then you need to have an amplifier which is rated at 600w at 8ohms to get the best possible clean sound[QUOTE]

Shaun:
I think the confusion arises due to the the way manufactuers label the specs on their cabs. Most pro speakers will give you two ratings for their speakers: RMS (also called continuous) & Program (Also called music). Prog rating is double the RMS rating.

Hence a 300watt RMS speaker is also rated 600watts prog and can be fed 600watts of amp power. Most manufactures recommend this. e.g JBL Sound Factor series is rated 250watts RMS, 500watts Prog. JBL recommend 500watts of amp power for that cab. Peavey Hisys 2RX is rated 500watts RMS, 1000watts Prog. Peavey recommends 1000watts of amp power for the speaker.

RMS rating is usually calculated using a continuous sine wave/pink noise signal which is far too demanding on speakers that a music signal. Therefore a prog rating is derived to allow for proper matching of amp power to speaker power.