Speaker vs Amp power, who is right?

[wwwid]

I am trying to find out should I get a amp that's more powerful than my speakers or the other way around. I've came across 2 articles on the internet that seem to say the opposite things. But who is right?

Amp should be 2 x more powerful
http://www.jblpro.com/pages/general_faq.htm

Speakers should be 2 x more powerful
http://www.amplifiedparts.com/tech_corner/speaker_impedance_power_handling_and_wiring

Thanks

 

[RobinKidderminster]

In most domestic.systems no need to worry. Usually the speakers will exceed the amp in terms of max wattage. Others will elaborate but may need clarification regarsing your spwcific requirements.

 

[alienmango]

If you're going too use a hifi as domestically intended and treat it with respect then do not worry too much.

If you may push the boundries I'd reccommend the amp is more powerful. I've messed around a lot in my time and have never had a speaker fail but I've seen many amps overheat and shut down (sometimes permanently).

From what I've seen with smaller 2 way speakers you're much more likely to experience mechanical damage from overexcursion if there is content below the tuning frequency. For example from my experience with both budget and midrange (£150 and £500) bookshelves they can take much more power thermally than they can in reality: they just suffer from overexcursion at relatively low levels of rms power.

There are exceptions everywhere obviously...but with larger speakers (or music without low bass) you're more likely at higher volumes to overheat (and clip) the amp or if you really crank it like an idiot potentially you could cause thermal failure of the woofers/crossover/tweeter.

For music with a lot of dynamic range you want an amp that can deliver high amounts of power for short burst of time or you will get amp clipping, distortion and potentially damage to speakers. In these circumtances amps that can deliver this will lead to great, dynamic, undistorted sound.

Hope this helps.

 

[davedotco]

I think the real question is how do I make sure that I don't damage my loudspeakers.

The simple answer is to use a little common sense, but it helps tremendously if you have a basic understanding of how an amplifier drives a loudspeaker.

Take a decent 50watt integrated amplifier, one with honest spec, decent power supply etc, etc. Such an amplifier will deliver around 70 watts peak, after which the amplifier will clip. On recorded music with even a limited dynamic range the average power will be in the region of 5-10 watts, and this is with the amplifier running flat out.

It us unlikely that the continuous power being delivered by such an amplifier would develop enough 'heating' power to damage any speaker.

But this is in 'normal' use, ie mainstream music being played at sensible (even pretty loud) levels.

The problems arise when we step outside of the above scenario, bass heavy music, excessive use of volume and particularly bass controls can very quickly drive the amplifier into overload or clipping.

When this happens all kinds of things start to happen, squared off (clipped) signals contain huge amounts of high frequencies, sufficient in fact to burn out tweeters in some cases but the really big issues happen at the bass end.

Transient DC offset, produced by some amplifiers in extremis, can destroy a bass driver in a fraction of a second but even well behaved amplifiers can cause problems by overdriving them on low bass signals, often distorted by bass boost. Many ported loudspeakers have minimal 'loading' in the low bass, causing excessive cone excursion which can also destroy bass units pretty quickly.

The primary issue is misuse, learning and understanding the limitations of your, or any, system is the key, if you don't overdrive the system you will have no problems.

 

[MeanandGreen]

Impedance matching is the crucial element here. Technically a speaker doesn't have a specific power handling capacity, and a lot of manufacturers give a recommended amplifier power guide as a rating (for e.g 50w-100w range). This is because it is usually under powered amps running beyond their capacity and clipping/distorting the music signal which then leads to loudspeaker damage.

You are very unlikely to 'blow' a speaker rated at 50w with a 80w amp for example, but if you run a 20w amp at full capacity into the same 50w speaker then you'll have trouble.

As long as you match the impedance of amp and speaker (8 ohms for example) and don't run your amp up to clipping levels you'll be fine with pretty much any amp/speaker wattage.

 

[Thompsonuxb]

I'd go with more powerful amp.

I have a 5.1 reciever rated at 90wpc rms - driving a pair of 200w into 6ohm stereo speakers (all unused channels off). when driven the amp does not distort and it maintains control of the drivers stopping & starting on time so music does not sound 'loud'

outside the room the music does sound loud.

I had a stereo amp recently, rated at 60wpc it was unable to control the same speakers past the 9o'clock position on the volume dial and it did sound loud (distortion) - but I suspect it would have eventually damaged my speakers - never driven to cutting out.

low power speakers can handle high power amps, but big speakers will suck the life out of a small amp.

the rx is old now and I suspect the design provided a lump of a psu able to deliver when all channels at 90wpc are been driven (modern rx having multiple amps) which can only guess it makes the amp capable when driving just the front channels.
while the stereo amp psu must be smaller and less capable.

 

[wwwid]

Thanks for all the replies.

I do want to push the system to the limit (or very close to it) without disrupting the sound, so should I get more Amp power or more powerful speaker?

 

[Thompsonuxb]

er.... amp power..... previous post

don' be put off reading through the replys because of these scientist and engineer....... :roll:

 

[MeanandGreen]

Amplifier power is what you need to prioritise. Speakers do not have power unless they are active speakers the power rating is an amplifier guide.

impedance matching (ohms) and high sensitivity speakers (db/w/m) combined with an amplifier capeable of delivering clean undistoreted power output will give a system capeable of high volume levels without equipment damage or strain.

 

[davedotco]

Thanks for all the replies.

I do want to push the system to the limit (or very close to it) without disrupting the sound, so should I get more Amp power or more powerful speaker?

As I said above, it is all about common sense. It simply depends on the levels you want to play at and the kind of music you want to play.

The real answer to you question is to buy an amplifier/speaker combination that will allow you to play the music you want to hear at the volume levels that you want to play it at without having to 'push the system to the limit'.

Any half decent amplifier and speaker combination will work fine if kept within normal operating limits but many will fail, often catastrophically, if pushed beyond them. If you are determined to have an answer to what is a somewhat simplistic question, then, generally, the more powerful amplifier the better.

That said, understanding how hi-fi works and taking steps to optimise the performance to suit your particular requirements is the real answer.

If you can't be bothered with that and want something that is pretty much foolproof, I would point you at some of the active monitors mentioned in other recent threads, not only do they go pretty loud for the money but they will usually have limiters or some other form of overload pratection built in.

 

[jazul]

The JBLPro advice is meant for sound reinforcement use, where very high dynamic ranges can be found for live music, and tries to maximize the Sound Pressure Level while not risking the life of the speakers.

For canned music, lower amplifier powers can be used, as peak power is the limiting factor here.

On overengineered home systems that do not get pushed to the limit, it is not that critical. For outdoor use (occasional party(, sometimes it's easy to push the system too far and blow a transducer, so it's important to listen and avoid distortion, that may signal inminent trouble.

 

[RobinKidderminster]

Why would you 'want to push a system to its limit'?? I always push my Ferrari to its limit and drive around town at 190mph. I always felt happier taking my Reliant Robin to its limit of 50mph but felt a need for more power.

Maybe buy a system to suit your needs comfortably rather than worry about breaking it. :wall: