Power requirements for speakers to maximise performance.

tebbo65

Well-known Member
Having a bit of a re-config of my system and need advice on power requirements for speakers to maximise performance. What's got me thinking is a fellow AVF member suggested my LCR are under driven and would benefit from more power to improve dynamic range etc, even at lower volume? He also suggested XTZ's power rating is quite conservative.
See below more info on my present set up for initial advice. Note, I do need all channels driven by external power amps as I am about to introduce 2 x MiniDSP ddrc88BM's to try out Dirac.

So my question is, given that I may well be going to a 9.1.4 config (wides will be XTZ M6's), so will need an extra 2 channels of amplification what wattage rated power amps should I be looking at and should bi-amping the LCR be a consideration? Or am I over thinking it and what's in place is good enough?

Typical listening volume max -12dB.
All speakers crossed over with subs at 80Hz, so subs handle all the heavy lifting in the bass/sub bass region.
Distance from the LCR to the MLP is approx. 10ft.

Set up. (7.2.4)

  • LCR (XTZ M8's) 91,2dB 600w Peak 350w Cont 4-8 Ohm
  • Side Surrounds (XTZM6's) 89dB 300w Peak 150w Cont 4-8Ohm
Above currently powered by a Emotiva XPA-5 gen 2.
200w per channel; all channels driven; into 8 Ohms.
300w per channel; all channels driven; into 4 Ohms.
  • Rears (XTZ M6's) 89dB 300w Peak 150w Cont 4-8 Ohm
  • Over heads (XTZ S2's) 86dB 150w 75w Cont 8 Ohm
Above currently powered by a Nak AVP-1.
110w per channel; all channels driven; into 8 Ohms.
170w per channel; all channels driven; into 4 Ohms.

Thanks in advance.
 
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rccarguy2

Distinguished Member
You have to plenty already. That other person is talking crap. You don't need to replace those amps

Even a good stable 50w will provide enough clean SPL output.

There are dB calculator.availble just enter in details and it'll give back number's
 
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tebbo65

Well-known Member
You have to plenty already. That other person is talking crap. You don't need to replace those amps

Even a good stable 50w will provide enough clean SPL output.

There are dB calculator.availble just enter in details and it'll give back number's
Cool, thanks for that 👍🏻. Don't suppose you could post a link to a dB calculator could you?
Ta.
 
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kenshingintoki

Distinguished Member
I'd say your power reserve is plenty. If you're not happy or fancy a change, the next logical step up would be changing your speakers for some new ones IMO.
 
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tebbo65

Well-known Member
I'd say your power reserve is plenty. If you're not happy or fancy a change, the next logical step up would be changing your speakers for some new ones IMO.
Perfectly happy just need to think about extra amplification when I put wides in.
Love my XTZ's
 
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kenshingintoki

Distinguished Member
Perfectly happy just need to think about extra amplification when I put wides in.
Love my XTZ's
Perfect. I'd just continue as is then mate. :)

Switching amps is not going to transform the XTZ. Mild mild improvement/change. Changing speaker will if you ever fancy it.
 
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kenshingintoki

Distinguished Member
Perfectly happy just need to think about extra amplification when I put wides in.
Love my XTZ's
Interestign question.

Whats going to sound better?

a) £5,000 speakers with £1,000 amplifier which has enough power to play them well above reference.
OR
b) £2,000 speakers with £4,000 expensive amplifier.


I think its really really easy to fall into b) very quickly.
 
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tebbo65

Well-known Member

Interestign question.

Whats going to sound better?

a) £5,000 speakers with £1,000 amplifier which has enough power to play them well above reference.
OR
b) £2,000 speakers with £4,000 expensive amplifier.


I think its really really easy to fall into b) very quickly.
True but slightly flawed in that really expensive speakers can sound crap.
But totally get want you say.
 
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kenshingintoki

Distinguished Member
True but slightly flawed in that really expensive speakers can sound crap.
Bit totally get want you say.
Which expensive ones have you heard which sound crap?
 
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tebbo65

Well-known Member
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tebbo65

Well-known Member
Which expensive ones have you heard which sound crap?
Didn't mean this to get into a speaker debate....whoops!!! Obviously that's down to subjective personal opinion.
Was just looking for a bit of power vs speaker advice which your good self and @rccarguy2 have answered perfectly thank you 👍🏻🤛🏻.
 
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kenshingintoki

Distinguished Member
Didn't mean this to get into a speaker debate....whoops!!! Obviously that's down to subjective personal opinion.
Was just looking for a bit of power vs speaker advice which your good self and @rccarguy2 have answered perfectly thank you 👍🏻🤛🏻.
Was just curious mate. Every time I've heard something more expensive from a good brand, its always sounded better. Audio for me and AV in general as long as u stick to the true and trusted manfuacturers, seem to always give u what u pay for.

except speaker cables lol
 
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Mr Wolf

Well-known Member
This calculator is actually very unreliable as it assumes a dispersion loss of 6dB per doubling of distance which would only be appropriate if you were listening outside. In a room this dispersion loss is much less due to reflected sound energy and typically between 3dB and 4dB per doubling of distance (I've measured mine as being 3.2dB if the speaker is on axis at the MLP).

THX Ultra amp/speaker certifications effectively say you need to feed 100W into an 89dB speaker to be able to cleanly hit 105dB cinema reference level in a 3,000Ft3 room at 12Ft distance. As you have 2dB more sensitive speakers and listen at -12dB, that's 14dB less amp gain you need which requires only 4% of the power requirement. So you should need no more than 4 watts into 8-Ohms amplifier power per channel even on the loudest possible peaks.

The reality is that most people need far less amplifier power than they think.
 
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dlaloum

Member
This calculator is actually very unreliable as it assumes a dispersion loss of 6dB per doubling of distance which would only be appropriate if you were listening outside. In a room this dispersion loss is much less due to reflected sound energy and typically between 3dB and 4dB per doubling of distance (I've measured mine as being 3.2dB if the speaker is on axis at the MLP).

THX Ultra amp/speaker certifications effectively say you need to feed 100W into an 89dB speaker to be able to cleanly hit 105dB cinema reference level in a 3,000Ft3 room at 12Ft distance. As you have 2dB more sensitive speakers and listen at -12dB, that's 14dB less amp gain you need which requires only 4% of the power requirement. So you should need no more than 4 watts into 8-Ohms amplifier power per channel even on the loudest possible peaks.

The reality is that most people need far less amplifier power than they think.
The exception, is where speakers have low impedance "troughs" in their frequency range - areas where the impedance drops below 4ohms - or below 2 ohms in the case of my speakers...

Many quite powerful amps, are simply not stable into 2 ohms - and start to generate various nasties.... (distortion).... it is one of the main reason amps can sound different into SOME speakers.

An ideal perfect amp should put out twice the Watts into 4 ohm (as compared to its 8 ohm rating) - and then double again into 2 ohm.
So a 100W amp, should in theory, put out 200W into 4 ohm and 400W into 8ohm

My Gallo speakers are "nominally" 8ohm according to their specification - but if you check out tests - they actually drop to 3 ohm in the bass and 1.6 ohm at the high end....

This can make them quite tough to handle for many amps!

Look for amps that double down as described above (rare and very expensive) - or more commonly for high current amps, they will multiply by around 1.7x into 4ohms and then 1.5x more into 2 ohm.... at the very least the amp should state that it is "Stable" into 2 ohm.

In some amps case, the actual power amp circuits can do the job, but the power supply can't maintain it for long (low impedance requires HUGE current) - so you will find some amps with "peak" or "dynamic" power ratings that get close to the ideal, while the continuous ratings don't - often such amps will do fine...
 
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rccarguy2

Distinguished Member
Class a amps typically have perfect power output for every halving of speaker load
 
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Mr Wolf

Well-known Member
The exception, is where speakers have low impedance "troughs" in their frequency range - areas where the impedance drops below 4ohms - or below 2 ohms in the case of my speakers...

Many quite powerful amps, are simply not stable into 2 ohms - and start to generate various nasties.... (distortion).... it is one of the main reason amps can sound different into SOME speakers.

An ideal perfect amp should put out twice the Watts into 4 ohm (as compared to its 8 ohm rating) - and then double again into 2 ohm.
So a 100W amp, should in theory, put out 200W into 4 ohm and 400W into 8ohm

My Gallo speakers are "nominally" 8ohm according to their specification - but if you check out tests - they actually drop to 3 ohm in the bass and 1.6 ohm at the high end....

This can make them quite tough to handle for many amps!

Look for amps that double down as described above (rare and very expensive) - or more commonly for high current amps, they will multiply by around 1.7x into 4ohms and then 1.5x more into 2 ohm.... at the very least the amp should state that it is "Stable" into 2 ohm.

In some amps case, the actual power amp circuits can do the job, but the power supply can't maintain it for long (low impedance requires HUGE current) - so you will find some amps with "peak" or "dynamic" power ratings that get close to the ideal, while the continuous ratings don't - often such amps will do fine...
I know the theory and overall agree with what you're saying. In fact with certain speakers it can be even more demanding than you're suggesting due to added power inefficiency presented by large phase angles.

That said, this potential impedance/current swing issue really needs to be put into perspective where the overall power requirement is still relatively low and well within a PSU's current capabilities. For example, take a situation like the OPs where he may need 4W output into 8-Ohms. That's a peak voltage to the speaker of 5.66V at 0.71A. Even in a 3-Ohm impedance dip that's still only a maximum power draw of 10.7W on 1.89A of current. That's the same amount of current that would be drawn when outputting 29W into an 8-Ohm load so it shouldn't be particularly demanding. And all this is happening in transient peaks that last fractions of a second so that the PSU demands can be smoothed by large capacitors.

If you're driving a system pretty hard with difficult to drive speakers then I agree that choice of amplifier can become very critical. Personally I try and stay away from those sort of speakers.

Out of interest, the THX Ultra standard requires amps to be stable into 3.2-Ohm loads and be able to cover maximum current swings of up to 18A.
 
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tebbo65

Well-known Member
I'm only leaving likes / useful / thanks etc and not commenting, because you boys sure know your stuff and it's technically way over my head.
But get the gist 👍🏻.
 
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rccarguy2

Distinguished Member
If the amplifiers are capable enough you don't need to worry about speaker impedance or efficiency then you can buy whatever speakers you like.
 
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D

Deleted member 901590

Guest
If the amplifiers are capable enough you don't need to worry about speaker impedance or efficiency then you can buy whatever speakers you like.

Whilst that's true, there has to be a sensible compromise between the two and that's where most people go.

Especially in early 2022 when we have all had notification from our energy suppliers of how much a kWh costs.

The tree huggers should be selling us electric cars and high sensitivity speakers 🤣
 
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Mr Wolf

Well-known Member
I'm only leaving likes / useful / thanks etc and not commenting, because you boys sure know your stuff and it's technically way over my head.
But get the gist 👍🏻.
The amp power need thing is an interesting subject that comes up a lot on here so it's always a useful discussion. IMO there's a large degree of misunderstanding which often leads to unnecessarily over-specifying system amplification.

Either way you don't need to worry. If you're listening at -12db while seated 10ft from a 91db speaker powered by a 200W power amp then trust me that you've got headroom on your headroom.

If the amplifiers are capable enough you don't need to worry about speaker impedance or efficiency then you can buy whatever speakers you like.
Nice idea (if a bit expensive) but it's actually not true as doubling power only increases output by 3dB and you'll soon hit amplification or speaker power handling limits if you choose very inefficient speakers and try to go very loud with them. It's far better to go with efficient speakers in the first place - buy those you can pretty much use any amplifier with them you want to.

If you want to see some maths on it, here's a table I created a while back that shows the amplifier power required for a speaker to be able to hit reference level (105dB) at 1M anechoically. In a typical room this would probably equate to the power required to support listening between 0dB and -7dB volume depending on room size/reflectivity and seating distance.

1647946240349.png


I hate to be the bearer of bad news but even a mid-range AVR using very efficient speakers can have way more SPL headroom than a beefy power amp on inefficient speakers.
 
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rccarguy2

Distinguished Member
I understand don't need gigawatts , I have amps between 60w and 200w into 8ohm, but there is sound quality issue with AVR just found they don't sound that great at higher volumes, even a good dedicated audiolab 8000sx outclassed AVR. So why spend money on higher end avr, put money into poweramps even iota 7ch is affordable and considering you may spend thousands on the connected speakers it's small percentage.
 
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tebbo65

Well-known Member
This has all been a great education and I thank you all 🙏🏻.
So going back to my original post #1. Considering my speaker specs, environment and listening habits, if I do eventually jump from 7 base layer channels to 9, if I drop out the Emotiva and replace it with an IOTAVX AVXP1 or a used Nak if it crops up, I'll be okay?
 
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rccarguy2

Distinguished Member
This has all been a great education and I thank you all 🙏🏻.
So going back to my original post #1. Considering my speaker specs, environment and listening habits, if I do eventually jump from 7 base layer channels to 9, if I drop out the Emotiva and replace it with an IOTAVX AVXP1 or a used Nak if it crops up, I'll be okay?

Emotiva, iota and nakamichi are all made by same OEM. They're pretty much same amp.

Why would you change one to anothrr?
 
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