Confused about Speakers

[moy71]

Please help me understand.   I have a 100W amp.  But my speakers are rated at only 50W 8ohms 96db sensitivity.    Should i get a speakers with higher watts?

[David A]

I wouldn't have thought a 100w amp would be an issue if your speakers are rated at 50w power handling. A bit of extra headroom isn't a bad thing. The bigger risk is under-powering the speakers and driving them into clipping. But just to check, what amp and speakers do you have?

[moy71]

Thanks for the reply.

The amp i am using is an Audiolab 8200P and the speakers i plan to get is an 80s vintage KEF Concerto with only 50w.

 

The current speakers i have is a Klipsch 610F which is 340w.   

 

My concern is the amp maybe  too much for the KEF speakers?

 

 

 

 

[sir sanders zingmore]

Frankly I usually completely ignore the power ratings on speakers - who even knows what they mean?
They might mean the long term power handling ability, in which case if you are pumping more than 50w into 96 db speakers long term, you are probably more in danger of damaging your hearing than anything else (transient peaks are fine). 

On the flip side having an underpowered amp might mean that you need to turn it up so high that it clips. Sending a clipped signal to your speakers is a sure way to damage them. 
In short, as long as you are sensible with the volume control, you are better off having an amp that can deliver more power than you need as opposed to one which delivers less power than you need. 

[aechmea]

7 hours ago, moy71 said:

Please help me understand.   I have a 100W amp.  But my speakers are rated at only 50W 8ohms 96db sensitivity.    Should i get a speakers with higher watts?

No. Sensible use of the volume knob is all that is required.  Better to have an over powered amp than not enough.

 

It is a common situation for people to have an amp that can't reproduce the peaks without it clipping.  A clipped signal contains a lot of high frequencies (that weren't there before clipping) which can be damaging to tweeters.

 

 

[moy71]

Understand thank you all, makes perfect sense.  

[almikel]

I agree with all the responses above - be cautious with the volume knob and keep a sympathetic ear out for signs of stress when the wick is turned up.

 

The guideline of having a bigger wattage amp than the speakers can be taken too far.

 

A 500W amp could easily destroy speakers designed for say 25W if someone without a sympathetic ear gets hold of the volume control with a few drinks on board

 

OTOH a 25W amp will likely never blow the tweeters on 500W speakers without deliberate abuse. Any reasonable listener will hear objectionable distortion due to clipping of the amp, and turn it down (hopefully!)

 

Numerous times I've discovered blown tweeters and woofers on the morning after a party

 

Mike

[Ars Paart]

50W into those speakers are going to be *very* loud in any normal listening situation. 

[almikel]

2 hours ago, Ars Paart said:

50W into those speakers are going to be *very* loud in any normal listening situation. 

agreed - that's what the volume knob is for 

[rantan]

One of my pet hates is the often stated subject of speakers having a 100 or 150 or something RMS power rating.

Without meaning to offend anybody it should be blatantly obvious that loudspeakers are passive devices and have NO output power of their own.

Without an amplifier they cannot make a sound and yet we see all the time statements like speaker output 150 watts RMS.

 

I have noted this in particular with a (no name mentioned ) local speaker builder,  with a label on the back stating  " 100 watts RMS," and  many others who also do that.

 ALL of them should know better.

 

One often hears lay people saying things like  "jeez these are great they put out 150 watts"

An actual power handling figure is almost meaningless and during my career in the audio industry I cannot count how often people would visit us  saying these are 150 watt speakers and my amp is only 50 and still they got blown up". ( I will leave you good people  to work out why )

 

My point is that we should move away from the Power rating for speakers as 99% of people never even use 20 watts of a 100 watt amplifier in domestic situations for listening and quite often not even that much.

[almikel]

23 minutes ago, rantan said:

One of my pet hates is the often stated subject of speakers having a 100 or 150 or something RMS power rating.

Without meaning to offend anybody it should be blatantly obvious that loudspeakers are passive devices and have NO output power of their own.

Without an amplifier they cannot make a sound and yet we see all the time statements like speaker output 150 watts RMS.

 

I have noted this in particular with a (no name mentioned ) local speaker builder,  with a label on the back stating  " 100 watts RMS," and  many others who also do that.

 ALL of them should know better.

 

One often hears lay people saying things like  "jeez these are great they put out 150 watts"

An actual power handling figure is almost meaningless and during my career in the audio industry I cannot count how often people would visit us  saying these are 150 watt speakers and my amp is only 50 and still they got blown up". ( I will leave you good people  to work out why )

 

My point is that we should move away from the Power rating for speakers as 99% of people never even use 20 watts of a 100 watt amplifier in domestic situations for listening and quite often not even that much.

and let's not forget that rms relates to current and voltage not power!

there is no such thing as rms power.

[rantan]

57 minutes ago, almikel said:

nd let's not forget that rms relates to current and voltage not power!

there is no such thing as rms power.

 

100%

 

I should have mentioned that but in my haste to vent about something that annoys me, I forgot to mention it.

 

Thanks

[aussievintage]

14 hours ago, rantan said:

One of my pet hates is the often stated subject of speakers having a 100 or 150 or something RMS power rating.

Without meaning to offend anybody it should be blatantly obvious that loudspeakers are passive devices and have NO output power of their own.

Without an amplifier they cannot make a sound and yet we see all the time statements like speaker output 150 watts RMS.

 

 

I never had a problem with it, coming from the perspective of the electronics hobby, and playing guitar in a band.  As far as I was concerned, speakers were labelled with the amount of power they could tolerate without burning out.  So for a 60 watt guitar amp, two 30 watt speakers in a cabinet were what was required for reliability.  Of course, you could put more, say 100 watts worth of speakers in the cabinet if you wanted - opposite of what is said these days where underpowered speaker systems are used, based on the assumption you won't turn it up past where it distorts.

 

I never once thought it was an indicator of them being anything other than passive. 

 

In the home, it was less clear, only because they started lying about power handling, and developed new terms like  watts of music handling ability (can't remember the actual term used, but it implied they could handle more power because music was an intermittent 'soft' source).  I think the term "Watts RMS" was a kickback on this,  trying to emphasise that the speaker was rated in terms of true electrical power, not some marketing term.

[muon*]

It's just a "recommended" amp wattage range to use, nothing more or less.

 

For instance mine are 20 - 300W recommended.

[aussievintage]

15 minutes ago, muon* said:

It's just a "recommended" amp wattage range to use, nothing more or less.

 

For instance mine are 20 - 300W recommended.

 

Yes, but that method of rating speakers is modern, and particular to hifi stuff.        It really did start out as a maximum electrical power thing, and people sized PA systems, and instrument amps accordingly.  Always had to have speakers rated more than the amp was going to put into them.

[rantan]

Ok, so here's the thing.

If we look at the two sets of specifications listed, the set for the KEF speakers states " Maximum allowable input 50 watts music".   This is at least somewhat clear in stating  that the speakers can operate effectively with a maximum continuous input from the amplifier of 50 watts, although I am sure everybody here knows that during the vast majority of domestic listening levels we never even get close to a 50 watts output from the amplifier.

Then take a look at the specs from Klipsch which state "power 340 watts" which frankly is not only ridiculous but also entirely meaningless.

Please remember that this curious stat is on a speaker that has a sensitivity rating of 94 dB and an impedance of 8 ohms, so god-only-knows what they are trying to say

What does it actually mean and what can your average non enthusiast glean from it? I venture to say nothing except some macho idea from the marketing department.

It is completely un necessary and only further confuses its target market.

 

I shall shut up now but I think you catch my drift.

[moy71]

Thank you all for the valuable input.   Just as an update, the Kef concerto speakers are now home and connected to the amp.  Wonderful sound and at the amp volume knob setting of -25db, its already pretty loud.   Happy days.

[bob_m_54]

1 hour ago, aussievintage said:

In the home, it was less clear, only because they started lying about power handling, and developed new terms like  watts of music handling ability (can't remember the actual term used, but it implied they could handle more power because music was an intermittent 'soft' source).  I think the term "Watts RMS" was a kickback on this,  trying to emphasise that the speaker was rated in terms of true electrical power, not some marketing term.

The rating in Peak power in R.M.S. has been around since well before the P.M.P.O. (which I think is what you're talking about) ratings started coming out. The Peak Music Power Output came about in the late 80s, when cheap amps & Boom Boxes started to appear with ridiculous figures like a 2000W PMPO, which has no actual recognised way of being measured.

 

But as you say, Most vintage stuff was marked with Peak Power XXW, and/or Peak Power XXW RMS, basically as a warning that if your amp can output more that that, you need to be careful with the volume setting. As in these Sonics AS-350 speakers from the early to mid 70s.

 

 

 

[sir sanders zingmore]

12 hours ago, rantan said:

" Maximum allowable input 50 watts music".   This is at least somewhat clear in stating  that the speakers can operate effectively with a maximum continuous input from the amplifier of 50 watts,

You are probably correct but, I interpret that very differently. Perhaps because "watts music" sounds to me like the old meaningless "5 billion watts peak music power output " which was something like the maximum power available for a femtosecond.

I guess to me it just shows how confusing these things can be when they aren't clearly defined

[almikel]

On 11/10/2024 at 9:54 AM, rantan said:

If we look at the two sets of specifications listed, the set for the KEF speakers states " Maximum allowable input 50 watts music".   This is at least somewhat clear in stating  that the speakers can operate effectively with a maximum continuous input from the amplifier of 50 watts

I agree with @sir sanders zingmore - if you delivered 50W of power to the KEF speakers continuously - say with pink noise split appropriately across the spectrum according to some standard of typical music - I think the voicecoils on one of the drivers would overheat and fail fairly quickly.

The KEF spec says "Maximum allowable input 50 watts music". - this does not mean continuous!

 

20 hours ago, sir sanders zingmore said:

I guess to me it just shows how confusing these things can be when they aren't clearly defined

Unfortunately, these things can't be easily defined

Drivers within speakers have 2 limitations - excursion limits and thermal limits.

 

Excursion limits are easy to understand - especially for anyone that's heard a woofer driver hitting Xmech and heard the driver "poling", ie mechanically hitting things beyond its expected travel.

 

Thermal limits are harder to detect in advance of driver failure ...IMVHO our sense of smell is vastly underrated in detecting stress in speakers and amps...

...If I'm pushing my system hard (which is pretty often), I keep an eye out for clip lights and driver excursion, but I will turn it down when I can smell the gear is working hard...

 

...it's about being sympathetic to your gear - hear/see/smell stress - turn it down!

 

Mike

 

 

 

 

[andyr]

On 11/10/2024 at 11:31 AM, moy71 said:

Thank you all for the valuable input.   Just as an update, the Kef concerto speakers are now home and connected to the amp.  Wonderful sound and at the amp volume knob setting of -25db, its already pretty loud.   Happy days.

 

Excellent!  

 

Just as a matter of interest ... what does a "volume knob setting of -25db" mean, in terms of your Audiolab 8200P's output?  (1/18th of its rated output of 100w  =  ~6w?)

 

[moy71]

The amp's volume knob isnt scaled from 0 to whatever number.  Instead, there is an LED display with the  lowest volume at -78.  Max volume is +8.   I have no idea what output  power that translates to.

Edited October 12, 2024 by moy71

[aussievintage]

9 hours ago, moy71 said:

Max volume is +8.   I have no idea what output  power that translates to.

 

My hope would be that 0 corresponds to claimed output power as per the specifications.  +8 would be greater than that by 8 db but exceeding the disortion figures.  no guarantees though  

Edited October 12, 2024 by aussievintage

[sir sanders zingmore]

18 minutes ago, aussievintage said:

 

My hope would be that 0 corresponds to claimed output power as per the specifications.  +8 would be greater than that by 8 db but exceeding the disortion figures.  no guarantees though  

I imagine that’s correct if the input is at the voltage require for full output. 
 

I imagine the +8 is for situations where, say the voltage required for full output is 2.5v but your DAC can only send 1.5 volts. In that case you might need to turn it up higher than zero (and possibly still not hit maximum output depending on how much voltage your DAC can send)

[aussievintage]

7 minutes ago, sir sanders zingmore said:

I imagine that’s correct if the input is at the voltage require for full output. 

 

If the meter is showing the input signal, than yes. ( For some reason I got the impression it was showing the power out.)