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post #1 of 24 Old 09-02-2015, 01:11 PM - Thread Starter
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Looking for some clarification on speaker power handling

I'm trying to get a better understanding of speaker component power handling. As this is my first proper set of speakers I'm trying to be over-cautious so I don't wreck anything.

I have Polk LSiM 705(2),706c(1),703(4). In the manual it only lists recommended amp as "250w". I've tried emailing them to clarify, but received no response. I'll have to call sometime during the day.

From my calculations if we assume the 250w is peak power handling, that would put the maximum distance to attain reference level at 6 feet from listening position. Obviously this number is "fluff" and would depend on the frequencies.

One thing I need a better understanding of is how speakers handle peaks. Audyssey can boost by up to 9db, which is incredibly sketchy from my lay perspective. From running a 30hz-20khz ~88db REW sweep on my surrounds with crossover disabled, it made them bottom out. (Stupid mistake on my part)

Obviously for bass I'll have crossover enabled and I can physically see how much excursion is happening roughly. What I'm worried about is a 9db boost in tweeter or midrange frequencies. If I play at reference, does that extra 9db narrow boost suddenly smoke my tweeter? Or, do tweeters handle peaks differently than woofers?

Also, assuming there is no boost, if I am running my speakers crossed over, and they're not having issues with the woofers, does that mean I can move them further away, or will the tweeters also be near their limits. Basically I'm wondering if tweeters have more output potential and woofers are the limiting factor on most speakers. I understand this is relatively hypothetical without the specific driver information for my speaker.

Thanks for your help. I realize it's very specific. If there's something I can read to understand better that would be great too, I just don't know what term to google, as everything I've searched hasn't returned anything useful.

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Last edited by boifido; 09-02-2015 at 01:21 PM.
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post #2 of 24 Old Yesterday, 12:15 AM
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Your speakers have the longest warranty of anything in your stereo for a reason: they are the least likely part to break. As long as you use them as intended, typical living room music and movie use, you should be fine. If you turn up the sound to the point of clipping and leave it there, or go even higher, then you can fry them, but why on earth would you do that?

It comforts people to buy speakers and pair them with amps under the assumption that "If my speaker can take X watts, and I buy an amp that is just shy of X watts, then I've optimized my system", but it isn't as simple as that. To truly describe what the power handling is of a speaker it takes at least a paragraph of text. What's that? No current manufacturer does that? Yes true, because that's not what people want to hear. They want to hear one number, maybe two, and think that it covers everything they need to know. Sorry, but it's not that simple. Lucky for you it also pretty much doesn't matter because sane people don't crank their amps up to the point that they distort ("clip"). Buy a receiver/amp with the features you like and be happy.

Want an example of what such a paragraph would contain? Read what the power handling is in the manual of this very nice Allison speaker for an example, but before you do, I'm warning you there will be a test afterwards, and I'm even going to let you cheat by giving you the multiple choice question beforehand, making it easy:

What is the power handling capability of the Allison CD-9 loudspeaker, expressed in watts, as per the manufacturer?
A) 20
B) 40
C) 90
D) 190
E) 750
F) all of the above

http://www.classicspeakerpages.net/l...anual_pg4.html
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post #3 of 24 Unread Yesterday, 05:43 AM
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Quote:
Originally Posted by boifido View Post
I have Polk LSiM 705(2),706c(1),703(4). In the manual it only lists recommended amp as "250w". I've tried emailing them to clarify, but received no response. I'll have to call sometime during the day.
The specs on line state the "recommended amplifier power" is 20-250W.
Quote:
Originally Posted by boifido View Post
From my calculations if we assume the 250w is peak power handling,
"recommended amplifier power" is not the same as "peak power handling". It's a nonsense spec. The actual figure would have to be stated as a maximum RMS power vs time. Pro speakers have this spec, often stated per driver.
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Originally Posted by boifido View Post
that would put the maximum distance to attain reference level at 6 feet from listening position. Obviously this number is "fluff" and would depend on the frequencies.
I got 7.2 feet.
Quote:
Originally Posted by boifido View Post
One thing I need a better understanding of is how speakers handle peaks. Audyssey can boost by up to 9db, which is incredibly sketchy from my lay perspective.
They limited the boost for reasons of power availability. Even if there were an area of response boosted that much (usually not) the actual power demands required in that area are program dependant, and thus highly time and amplitude dependant. It works out statistically.
Quote:
Originally Posted by boifido View Post
From running a 30hz-20khz ~88db REW sweep on my surrounds with crossover disabled, it made them bottom out. (Stupid mistake on my part)

Obviously for bass I'll have crossover enabled and I can physically see how much excursion is happening roughly. What I'm worried about is a 9db boost in tweeter or midrange frequencies. If I play at reference, does that extra 9db narrow boost suddenly smoke my tweeter?
Energy distribution always has tweeters receiving a fraction of the total power. It's not a problem. Do you read reports of Audyssey routinely blowing tweeters? Of course not.
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Or, do tweeters handle peaks differently than woofers?
Yes they do, they burn out more quickly when their maximum is exceeded. However, spectral energy distribution ensures they don't get but a fraction of the total power in any common audio signal. Sweeps and tones are the exception, and should always be run at low levels.
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Originally Posted by boifido View Post
Also, assuming there is no boost, if I am running my speakers crossed over, and they're not having issues with the woofers, does that mean I can move them further away, or will the tweeters also be near their limits. Basically I'm wondering if tweeters have more output potential and woofers are the limiting factor on most speakers. I understand this is relatively hypothetical without the specific driver information for my speaker.
You are overthinking this. SPL vs power calculations are based on nominal figures, broad band. You have lots of fudge room. Moving your speakers to 10' may result in slightly lower than 85dB + 20dB maximum capability, but in practice, nobody uses that at home. The Polks are not made to do it, and are not THX certified. Big deal. They'll still play loud enough. Most home listeners are at -10dB re: reference, or below. Reference is a large venue figure only.
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Originally Posted by boifido View Post
Thanks for your help. I realize it's very specific. If there's something I can read to understand better that would be great too, I just don't know what term to google, as everything I've searched hasn't returned anything useful.
Link if embed doesn't load
There's a small error in the spreadsheet somewhere, but I can't tell where from just the image. Check it with a few of the on-line SPL calculators.
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m.zilch makes some excellent points. (Edit: So does jaddie, who posted whilst I was typing.) Here are a few more points (not saying they are anything like excellent).

It is extremely unlikely anything like that kind of power is going to be used in the treble region. Look up Fletcher-Munson loudness curves. The tweeters generally have far less power-handling capacity than the woofers and they do not need it. HF sounds are typically 1/10 (-10 dB) to 1/100 (-20 dB) or less the power of LF signals.

105 dB is very, very loud; so it is 85 dB for that matter. I've never understood the rationale that everyone must listen at "reference". Furthermore, those peaks are very brief, more than likely only during explosions and such, when SQ is pretty much a don't care.

Chances are good that any decent AVR will power your speakers to ear-splitting levels.

I seriously doubt your surrounds are rated down to 30 Hz and that is probably why they bottomed out.

Most conventional speakers handle power the same way. Too much continuous power and they overheat, which can cause problems like burnt/warped voice coils, delamination of the coil and bruning/breaking of the glue, open wires, and magnetic force reduction from overheating the magnet. Excessive excursion can damage cones and surrounds as well as the voice coil and such. Connecting wires (from connectors on the speaker to the voice coil itself) can break. And so forth.

The best thing you can do for headroom and dynamic range is to get a good sub to go along with the speakers.

IME/IMO - Don
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Quote:
Originally Posted by boifido View Post
From my calculations if we assume the 250w is peak power handling, that would put the maximum distance to attain reference level at 6 feet from listening position. Obviously this number is "fluff" and would depend on the frequencies.
Quote:
Originally Posted by jaddie View Post
Check it with a few of the on-line SPL calculators.
Using the Crown Audio Calculator, I get 4 W to get to reference using the information below.

Listening Distance: 1.8288 m (You can tweak the distance since you know exactly were you will be listening from. Be sure to convert to meters.)
Sound Pressure Level at listening position: 85 dBSPL (THX reference level)
Speaker Sensitivity: 88 dB (Taken from speaker the LSiM 705 spec sheet)
Headroom: 4 dB

I've included an older post of a response to another member that had a question about amp sizing here.
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post #6 of 24 Unread Yesterday, 10:20 AM - Thread Starter
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Originally Posted by jaddie View Post
The specs on line state the "recommended amplifier power" is 20-250W.
"recommended amplifier power" is not the same as "peak power handling". It's a nonsense spec. The actual figure would have to be stated as a maximum RMS power vs time. Pro speakers have this spec, often stated per driver.
Right, I was just hoping it was conservative and meant it definitely could handle 250w program as calculated.

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Originally Posted by jaddie View Post
They limited the boost for reasons of power availability. Even if there were an area of response boosted that much (usually not) the actual power demands required in that area are program dependant, and thus highly time and amplitude dependant. It works out statistically.
Energy distribution always has tweeters receiving a fraction of the total power. It's not a problem. Do you read reports of Audyssey routinely blowing tweeters? Of course not.
Right, I was still cautious as if most people are playing at -10 or less, then the even a large range boost wouldn't affect them. I'm aware a 6db boost on the low end would double excursion so I was thinking something similar might happen on midrange and tweeter. I still need to learn about narrowband/peak speaker response.

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Originally Posted by jaddie View Post
You are overthinking this. SPL vs power calculations are based on nominal figures, broad band. You have lots of fudge room. Moving your speakers to 10' may result in slightly lower than 85dB + 20dB maximum capability, but in practice, nobody uses that at home. The Polks are not made to do it, and are not THX certified. Big deal. They'll still play loud enough. Most home listeners are at -10dB re: reference, or below. Reference is a large venue figure only
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Originally Posted by DonH50 View Post
105 dB is very, very loud; so it is 85 dB for that matter. I've never understood the rationale that everyone must listen at "reference". Furthermore, those peaks are very brief, more than likely only during explosions and such, when SQ is pretty much a don't care.

I've been playing at -5 and not finding it excessively loud for most movies. I could see being fine at reference which is why I was asking. For dynamic classical it might need 105db too. It's not that I'd listen to it all the time, I'm just trying to learn the limits of my system. (Never turn past -5 for example)

Since reference level is calculated per venue it shouldn't mean large venue only? Are you saying sound pressure in a small room is inherently louder perceived? Or is it that people sit far away with small speakers and use -10 because anything more distorts too much? I know just from playing with my room and placement I've gotten louder sounding not "too loud"

donH50: 85db is pretty loud too, which is why the dialnorm spec for no adjustment is -31db A weighted (~75DB). That should cover most of the damaging frequency range for ears as far as I'm aware, and it doesn't matter as much if 20hz is hitting 100db.

"Dolby Digital decoders standardize average loudness to -31 dBFS Leq(A), (31 dB below 0 dB full-scale digital, averaged over time)When a decoder receives a relatively quiet input signal, such as a feature film with a dialogue level setting of -31, it is assumed that the program
already matches the target level of -31 dB Leq(A) and therefore requires no further attenuation." (Same for DTS. Basically DialNorm on receivers is aiming for ~75db A weighted at reference, Which is why if some movies are mixed loud it will attenuate 4db for example.)"


Quote:
Originally Posted by DonH50 View Post
It is extremely unlikely anything like that kind of power is going to be used in the treble region. Look up Fletcher-Munson loudness curves. The tweeters generally have far less power-handling capacity than the woofers and they do not need it. HF sounds are typically 1/10 (-10 dB) to 1/100 (-20 dB) or less the power of LF signals.

I seriously doubt your surrounds are rated down to 30 Hz and that is probably why they bottomed out.

Most conventional speakers handle power the same way. Too much continuous power and they overheat, which can cause problems like burnt/warped voice coils, delamination of the coil and bruning/breaking of the glue, open wires, and magnetic force reduction from overheating the magnet. Excessive excursion can damage cones and surrounds as well as the voice coil and such. Connecting wires (from connectors on the speaker to the voice coil itself) can break. And so forth.

The best thing you can do for headroom and dynamic range is to get a good sub to go along with the speakers.
Quote:
Originally Posted by jaddie View Post
Yes they do, they burn out more quickly when their maximum is exceeded. However, spectral energy distribution ensures they don't get but a fraction of the total power in any common audio signal. Sweeps and tones are the exception, and should always be run at low levels.
I definitely have 2 subs and am using a 100hz crossover for the mains currently. That's why I'm more worried about the midrange/tweeter. The sweep example was just to give an idea of what I'm worried Audyssey would be doing similarly to the tweeter/midrange. Too much excursion too fast due to an 8db boost from ~60hz down.

Right, music is like pink noise so by the time you get to the tweeter range it's down in decibels a bunch. As you said though, tweeters have much less power handling as they are expecting a spectral distribution like that. So boosting/playing 10db louder would still scale equally. (If woofers expect arbitrary number 10, and get 10, and tweeters expect 2 and get 2, then doubling the requirement put on either one is still going to be the same issue even though the tweeter receives less.)

Quote:
Originally Posted by DonH50 View Post
Furthermore, those peaks are very brief, more than likely only during explosions and such, when SQ is pretty much a don't care.
Right, I don't care about a quick peak having distortion, I'm worried solely about breaking something. I guess my question I'm really trying to figure out is if short peaks past the limit of the speaker will cause it to break. For woofers I assume yes if the excursion caused something to rip. For tweeters/midrange I'm unaware.


Quote:
Originally Posted by jaddie View Post
There's a small error in the spreadsheet somewhere, but I can't tell where from just the image. Check it with a few of the on-line SPL calculators. I got 7.2 feet.
Quote:
Originally Posted by dmarqueset View Post
Using the Crown Audio Calculator, I get 4 W to get to reference using the information below.

Listening Distance: 1.8288 m (You can tweak the distance since you know exactly were you will be listening from. Be sure to convert to meters.)
Sound Pressure Level at listening position: 85 dBSPL (THX reference level)
Speaker Sensitivity: 88 dB (Taken from speaker the LSiM 705 spec sheet)
Headroom: 4 dB
jaddie: I meant to mention I was using numbers from a review which shows it's 5ohm nominal (or 86.5db/w). You might notice in the manual the spec is 2.83v, not 88db/w. I'm aware of manufacturers can pull the number out of their rear or twist specs.
dmarqueset: As above I was using 86.5db/2.83V


In my setup since I can have the speakers as close as I want, I'll need to find the minimum distance to get driver cohesion and then find a trade off with close placement output vs loss of seat to seat consistency which would benefit from far placement.

I guess the real lesson from all of this: For my next setup, say when I hit my 30s, I'll be looking at building a baffle wall with high efficiency drivers and active crossovers.
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Tweeters have the same failure mechanisms as any other driver.

Pink noise is equal energy per octave. It does not include things like target curves and such.

I'm a musician now and then so tend to be cautious with my ears. Listen as loudly as you wish.
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http://www.parts-express.com/in-line...older--070-609

In A/V reproduction accuracy, there is no concept of "accounting for taste". We don't "pick" the level of bass, etc., any more than we pick the ending of a play. High fidelity means an unmodified, neutral, exact copy (or "reproduction") of the original artist's tonal balance, timing, dynamics, etc..
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^Oh wait, this solution is simple and extremely inexpensive, you only need one per speaker, so that automatically makes it "audibly" unacceptable to audiophiles, yet they have no double blind listening tests to back their claims. Nevermind.

In A/V reproduction accuracy, there is no concept of "accounting for taste". We don't "pick" the level of bass, etc., any more than we pick the ending of a play. High fidelity means an unmodified, neutral, exact copy (or "reproduction") of the original artist's tonal balance, timing, dynamics, etc..
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Quote:
Originally Posted by boifido View Post

Since reference level is calculated per venue it shouldn't mean large venue only?
Reference is reference, it does not change because of the size of the venue.
Quote:
Originally Posted by boifido View Post
Are you saying sound pressure in a small room is inherently louder perceived? Or is it that people sit far away with small speakers and use -10 because anything more distorts too much? I know just from playing with my room and placement I've gotten louder sounding not "too loud".
Sound in a small room is perceived louder for a number of reasons. It's well known that home listening typically is done at a calibrated volume setting of -10 (re:reference) or less.
Quote:
Originally Posted by boifido View Post

"Dolby Digital decoders standardize average loudness to -31 dBFS Leq(A), (31 dB below 0 dB full-scale digital, averaged over time)When a decoder receives a relatively quiet input signal, such as a feature film with a dialogue level setting of -31, it is assumed that the program
already matches the target level of -31 dB Leq(A) and therefore requires no further attenuation." (Same for DTS. Basically DialNorm on receivers is aiming for ~75db A weighted at reference, Which is why if some movies are mixed loud it will attenuate 4db for example.)"
Dialog reference, and the Dialnorm metadata are not the same thing as reference level, and do not change the maximum requirements of playback at reference level.
Quote:
Originally Posted by boifido View Post

Right, music is like pink noise so by the time you get to the tweeter range it's down in decibels a bunch.
Not really. Pink noise is shaped so that its spectral distribution will display as "flat" on a real-time spectrum analyzer with fixed fractional octave bandwidth filters with prescribed characteristics. If you look at music on an RTA, it'll never be flat, and has much less energy at the top.
Quote:
Originally Posted by boifido View Post
As you said though, tweeters have much less power handling as they are expecting a spectral distribution like that. So boosting/playing 10db louder would still scale equally. (If woofers expect arbitrary number 10, and get 10, and tweeters expect 2 and get 2, then doubling the requirement put on either one is still going to be the same issue even though the tweeter receives less.)
Again, spectral distribution is not a constant. Looking at gains ahead of drivers will not predict how they handle power, or how much power they will have to handle.
Quote:
Originally Posted by boifido View Post

Right, I don't care about a quick peak having distortion, I'm worried solely about breaking something.
But the two are related...
Quote:
Originally Posted by boifido View Post
I guess my question I'm really trying to figure out is if short peaks past the limit of the speaker will cause it to break. For woofers I assume yes if the excursion caused something to rip. For tweeters/midrange I'm unaware.
Both woofers and tweeters have a power dissipation/heating issue. Woofers also have an Xmax issue. The power dissipation/heating limit is a level vs time curve, but different for all drivers of all kinds.
Quote:
Originally Posted by boifido View Post

jaddie: I meant to mention I was using numbers from a review which shows it's 5ohm nominal (or 86.5db/w). You might notice in the manual the spec is 2.83v, not 88db/w. I'm aware of manufacturers can pull the number out of their rear or twist specs.
dmarqueset: As above I was using 86.5db/2.83V
Well, I'm not going to try to confirm that, but in a quick search I did not come up with an impedance plot.
Quote:
Originally Posted by boifido View Post
In my setup since I can have the speakers as close as I want, I'll need to find the minimum distance to get driver cohesion and then find a trade off with close placement output vs loss of seat to seat consistency which would benefit from far placement.
So...going to run some polars, eh?
Quote:
Originally Posted by boifido View Post
I guess the real lesson from all of this: For my next setup, say when I hit my 30s, I'll be looking at building a baffle wall with high efficiency drivers and active crossovers.
...and a great big room!

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Power handling is intended to guide you about the maximum power the speaker can dissipate without damage. As mentioned above, it is more useful if it defines the power measurement and the time involved. Most speakers can handle far more power than your ears and room can handle. It is a specification you can safely ignore.

Understand also that the power calculators fail to consider room gain because they don't know anything about your room. So the calculators tend to suggest about 4 times the power you will actually dissipate in actual use in a typical home. For example, the highest level of power dissipation I have measured on my own system is 18 watts per channel and that was during an explosion in a movie sound track. My average power dissipation is less than one watt. If you have a system and/or room that would require more than the standard 50 to 100 watt per channel amplifier, you have an unusual situation to say the least.
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Quote:
Originally Posted by m. zillch View Post
^Oh wait, this solution is simple and extremely inexpensive, you only need one per speaker, so that automatically makes it "audibly" unacceptable to audiophiles, yet they have no double blind listening tests to back their claims. Nevermind.
I'm no audiophile (as in buying acoustical energy stones). From a quick search it looks like it would have to be placed after the crossover to protect the tweeter specifically, and fuses might not blow fast enough. I'll have to look into it more. Thanks for the interesting suggestion!

Quote:
Originally Posted by jaddie View Post
Reference is reference, it does not change because of the size of the venue.
Right I was meaning the perception of it

Quote:
Originally Posted by jaddie View Post
Sound in a small room is perceived louder for a number of reasons. It's well known that home listening typically is done at a calibrated volume setting of -10 (re:reference) or less.
I find theaters sound way louder and grating than my system at -5. That's why I was thinking home listening perception might also have to do with reflections/driver distortion. Maybe our local theaters are just terrible.


Quote:
Originally Posted by jaddie View Post
Dialog reference, and the Dialnorm metadata are not the same thing as reference level, and do not change the maximum requirements of playback at reference level.
Right, maximum requirements would be 105 still. I was making the point that the average at reference is apparently supposed to be 75db leq(a) long term, which would mean listening at reference level shouldn't cause hearing damage as ~85db is permissible 8 exposure. It was in response to DonH50 and his hearing damage comment.


Quote:
Originally Posted by jaddie View Post
Not really. Pink noise is shaped so that its spectral distribution will display as "flat" on a real-time spectrum analyzer with fixed fractional octave bandwidth filters with prescribed characteristics. If you look at music on an RTA, it'll never be flat, and has much less energy at the top.
Again, spectral distribution is not a constant. Looking at gains ahead of drivers will not predict how they handle power, or how much power they will have to handle.
Right but pink noise loses 3db an octave correct? I should have just said that music and real world content has a similar downward slope in intensity over frequency.

Quote:
Originally Posted by jaddie View Post
But the two are related...
Both woofers and tweeters have a power dissipation/heating issue. Woofers also have an Xmax issue. The power dissipation/heating limit is a level vs time curve, but different for all drivers of all kinds.
Well, I'm not going to try to confirm that, but in a quick search I did not come up with an impedance plot.
So...going to run some polars, eh?
...and a great big room!
I was just meaning I wasn't worried about slight distortion on a peak from being in a marginal range, so much as going past that point and blowing the driver. Obviously they are both related. So tweeters would be mostly susceptible to heating failure?

Measurement I'm basing calculations off of. Even if it's wrong that's only a 1.5db change anyways. Clearly for my next system I need 95+db/w efficiency as worrying about a decibel is close to the limit anyways.

Maybe for now I'll just assume peak program handling is 500w, cross over the speakers, get an emotiva or maybe something like an iNUKE NU4-6000. That would put reference at 8 feet. I'll cross my fingers that nothing catches on fire :P but most likely I'm just being overly cautious.

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Originally Posted by boifido View Post

Right, maximum requirements would be 105 still. I was making the point that the average at reference is apparently supposed to be 75db leq(a) long term, which would mean listening at reference level shouldn't cause hearing damage as ~85db is permissible 8 exposure. It was in response to DonH50 and his hearing damage comment.
Yeah, loud as it is, playing at ref doesn't damage hearing. Reference is 85, never 75. LeqA is not a measurement of reference level.
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Right but pink noise loses 3db an octave correct?
No, the "pinking filter" looses 3dB/oct, which is required to get pink to display flat on an RTA. Unfiltered white noise would display as rising 3dB/octave. Remember that an RTA has bands that are based on fractions of octaves, meaning that with flat white noise, the total energy in each band increases with frequency. Pink is just white compensated for spectrum analyzers.
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I was just meaning I wasn't worried about slight distortion on a peak from being in a marginal range, so much as going past that point and blowing the driver. Obviously they are both related. So tweeters would be mostly susceptible to heating failure?
Yes, not enough excursion to hit their magnets, usually.
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Maybe for now I'll just assume peak program handling is 500w, cross over the speakers, get an emotiva or maybe something like an iNUKE NU4-6000. That would put reference at 8 feet. I'll cross my fingers that nothing catches on fire :P but most likely I'm just being overly cautious.
What do you think might happen if you hit them with 500W?

The only way to hit reference in a room is with speaker efficiency/sensitivity. Look at any THX Ultra2 speaker, if they spec sensitivity, it's up in the low 90s at least. Reducing the listening distance gets you to near field of some speakers way to soon, and most aren't designed for near field operation.

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From a quick search it looks like it would have to be placed after the crossover to protect the tweeter specifically, and fuses might not blow fast enough.
Although there are speakers out there which fuse their tweeters only, I would suggest installing some suitable fuse holder, not necessarily the one I happened to link to, to the incoming full range signal. It's easier (which of course means "bad" in some audiophile camps).

What value fuse? Well use fast blow, not slow blow, for the most protection, and buy a bunch with the intention of purposefully blowing them as you step by step increase their values playing loud music for several minutes.

Random Example:

Step #1 Insert .5 Amp fuse and play very loud music. Wait.... 30 seconds later the fuse blows.
Step #2 Insert 1 Amp fuse and play very loud music. Wait... 2 minutes later the fuse blows.
Step #3 Insert 1.5 Amp fuse and play very loud music. Wait...4 minutes later fuse blows.
Step #4 Insert 2 Amp fuse and play very loud music. Wait... 10 minutes go by and the fuse just refuses to blow. Bingo! We have a winner!

Leave 2 Amp fuse in place and install the same in all the remaining speakers.

Obviously never play speakers at a volume which causes audible distress either due to limitation of the speakers or the amp. If you follow this adivise it is unlikely you even need fuses. After all, only .01% of speaker owners use them. If Polk blew up a lot they wouldn't be able to give you a 5 year warranty and they've been around for decades. [They may actually have protective circuits already built-in to their crossovers, beyond just filtration, by the way. Many companies do.]
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85 dB is too loud for me most of the time but that's preference. I typically listen 20 dB or so below the 0 dB reference on my pre/pro. We can tolerate much louder volume at LF (and very HF) than in the midrange. Long term hearing damage can occur for shorter, louder peaks repeated (or just once if loud enough) over the course of the music or movie.

These comments seem at odds, ironically:

Quote:
As this is my first proper set of speakers I'm trying to be over-cautious so I don't wreck anything.
Quote:
In the manual it only lists recommended amp as "250w".
Quote:
Maybe for now I'll just assume peak program handling is 500w, cross over the speakers, get an emotiva or maybe something like an iNUKE NU4-6000. That would put reference at 8 feet. I'll cross my fingers that nothing catches on fire :P but most likely I'm just being overly cautious.
It sounds like you want to listen at loud enough volumes that you should consider a more efficient (higher-sensitivity) set of speakers as jaddie suggested. 3 dB higher speaker efficiency requires 1/2 the amplifier power.

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Originally Posted by FMW View Post
Power handling is intended to guide you about the maximum power the speaker can dissipate without damage. As mentioned above, it is more useful if it defines the power measurement and the time involved. Most speakers can handle far more power than your ears and room can handle. It is a specification you can safely ignore.

Understand also that the power calculators fail to consider room gain because they don't know anything about your room. So the calculators tend to suggest about 4 times the power you will actually dissipate in actual use in a typical home. For example, the highest level of power dissipation I have measured on my own system is 18 watts per channel and that was during an explosion in a movie sound track. My average power dissipation is less than one watt. If you have a system and/or room that would require more than the standard 50 to 100 watt per channel amplifier, you have an unusual situation to say the least.
Right, and I'm purposely ignoring room gain in my calculations. I'm really going for over-engineering and in reality I'm being a worry wart haha.

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Originally Posted by m. zillch View Post
Although there are speakers out there which fuse their tweeters only, I would suggest installing some suitable fuse holder, not necessarily the one I happened to link to, to the incoming full range signal. It's easier (which of course means "bad" in some audiophile camps).

Obviously never play speakers at a volume which causes audible distress either due to limitation of the speakers or the amp. If you follow this adivise it is unlikely you even need fuses. After all, only .01% of speaker owners use them. If Polk blew up a lot they wouldn't be able to give you a 5 year warranty and they've been around for decades. [They may actually have protective circuits already built-in to their crossovers, by the way. Many companies do.]
Thanks for the advice. I'll look into that further.

For the audible distress would it affect the overall sound if only the peaks were an issue? I just don't have the real-life experience to know yet. Since the only time I'd be hitting 0 digital scale would be music/movies with huge crest factor. (I hope that's the right word) I use replaygain in foobar, so most music is scaled down. I'm aiming for 85db, so electronic music, for example would be scaled down by ~-10db making the peaks a non issue.

Basically I am worried about playing a classical piece absolutely fine, and then horns+kettle drums+singing all come in fortissimo with a huge peak above the average level where I'm hearing no distortion, and it goes from no distortion to blown.


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Yeah, loud as it is, playing at ref doesn't damage hearing. Reference is 85, never 75. LeqA is not a measurement of reference level.
No, the "pinking filter" looses 3dB/oct, which is required to get pink to display flat on an RTA. Unfiltered white noise would display as rising 3dB/octave. Remember that an RTA has bands that are based on fractions of octaves, meaning that with flat white noise, the total energy in each band increases with frequency. Pink is just white compensated for spectrum analyzers.
Yes, not enough excursion to hit their magnets, usually.

What do you think might happen if you hit them with 500W?

The only way to hit reference in a room is with speaker efficiency/sensitivity. Look at any THX Ultra2 speaker, if they spec sensitivity, it's up in the low 90s at least. Reducing the listening distance gets you to near field of some speakers way to soon, and most aren't designed for near field operation.
Well reference is technically 105db peaks, it's just calibrated using an 85db signal scaled -20 right? It would depend on the program content how loud it was. Which is why I was posting the quote about movies aiming for 75db leq(A) solely to make the point about hearing damage. Not power handling. Either way it's sort of an offtopic hearing damage discussion haha.

I'll have to learn more about pink noise then. And the analog side in general. Digital I'm pretty good with.

It depends on if that recommended amplifier spec for the polk was meant as rms or peak. And they wouldn't be hit with 500w due to crossovers, it's just me trying to over-engineer again. I would guess lots of flames would be the result

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Originally Posted by DonH50 View Post
85 dB is too loud for me most of the time but that's preference. I typically listen 20 dB or so below the 0 dB reference on my pre/pro. We can tolerate much louder volume at LF (and very HF) than in the midrange. Long term hearing damage can occur for shorter, louder peaks repeated (or just once if loud enough) over the course of the music or movie.

These comments seem at odds, ironically:

It sounds like you want to listen at loud enough volumes that you should consider a more efficient (higher-sensitivity) set of speakers as jaddie suggested. 3 dB higher speaker efficiency requires 1/2 the amplifier power.
I find for normal listening to music I like -10, meaning I'm listening at 75db (with music offset aiming for 85db at reference)



And to both you and Jaddie, it sounds like I should set -5 as the limit for these speakers, and for my next setup in say, 10 years, go for much higher efficiency designs to handle very high crest factor content. I'm happy with -5 anyways, and like the sound quality, so these weren't a terrible purchase, and a good learning experience. The 4 way design of the mains caused me to learn quite a bit about phase as integrating without cancellation with my subs was quite an ordeal.


Thanks everyone for your input!
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Well reference is technically 105db peaks, it's just calibrated using an 85db signal scaled -20 right?
Reference level is 85dB SPL. Maximum peak capability is theoretical, reference +20dB. Reality is much different, though. Real peak max is very hard to measure, you can't do it with tones or noise, or an SPL meter, so it's usually just generally calculated.

Reference is to be measured with the right pink noise signal, and a true RMS meter. Hate to open this can-o-worms, but the Dolby noise is 2dB off (because they used the wrong kind of meter years ago), so ref is technically 83dB SPL, and maximum peak is 103dB. But what's 2dB among friends and industry experts?
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And to both you and Jaddie, it sounds like I should set -5 as the limit for these speakers, and for my next setup in say, 10 years, go for much higher efficiency designs to handle very high crest factor content. I'm happy with -5 anyways, and like the sound quality, so these weren't a terrible purchase, and a good learning experience.
-5 relative to what? What are you setting anyway? BTW, what you want to do is design so you can reproduce a 0dBFS signal across the audio band without distortion, relative to reference level. You don't design for crest factor, you design for maximum, and let the crest fall wherever it is.

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The 4 way design of the mains caused me to learn quite a bit about phase as integrating without cancellation with my subs was quite an ordeal.
The splice is one of the dodgy spots.

And let me say, it's refreshing to hear from someone your age that is so engaged in this hobby. That's not typical, and most of us could easily be your dad or grandfather.

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For the audible distress would it affect the overall sound if only the peaks were an issue? I just don't have the real-life experience to know yet.
Remember how that Allison CD-9 speaker I linked to, the one that has pretty much the only meaningful power handling spec, a whole paragraph, which mentioned it was still comfortable with most frequencies at even 750 watts, if for only a tenth of a second? That's a peak. Speakers are usually quite forgiving of high level input if just for a peak. It is sustained, high level, not very dynamic music [highly compressed] which kills them.

Speakers blow up for only two reasons:

A) overpowering which causes a mechanical failure due to physical stress, such as over excursions ripping the voice-coil away from the spider or the cone smashing against the back plate [=My friend has a great name for this. He calls it "stamping". Ha!]

B) overpowering which heats up the voice-coil and melts it clean through [you get a puff of smoke and then zero sound] or the heat melts or warps some nearby structure, such as the bobbin, which causes the voice coil to rub, an audible problem which will continue even when lower more modest playback levels are attempted.

People who listen to classical music, even loud Mahler, are the least likely to damage their speakers, in my experience. They hear the onset of distortion, back down on the volume knob, and then are OK. No damage unless the volume knob is in another room and it took them a minute to run back to the living room to turn it down.

The main groups who get into trouble are:

A) Kids who don't care; they are at a dance party and they don't own the speakers themselves, so mild audible distress occurring ever 10 seconds or so, repeatedly for many minutes, on the louder sections doesn't phase them and they continue on until the speaker fries.

B) People who listen to, I think it is called "grunge", not sure, where there is so much distortion already dialed into the recording itself, inherent to the recording at any playback level, that to a new listener not familiar with the tune they might mistake the added distortion they are causing by overpowering their system as being "normal" for that song. Here's a good example. Although there is a lot of intentional distortion in the song it gets especially bad at about 5 minutes 30 seconds in:


See, if you don't know the song you wouldn't know if the sound you are hearing is "correct" or due to your excessive use of your volume knob! That's the danger. Distortion masks distortion.

On a side note, I remember when this album came out one reviewer said, "I can get better sounds out of my sink's garbage disposal". I think he was referring to the part I was highlighting. Haha. [I like this song though.]
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Originally Posted by jaddie View Post
Reference level is 85dB SPL. Maximum peak capability is theoretical, reference +20dB. Reality is much different, though. Real peak max is very hard to measure, you can't do it with tones or noise, or an SPL meter, so it's usually just generally calculated.

Reference is to be measured with the right pink noise signal, and a true RMS meter. Hate to open this can-o-worms, but the Dolby noise is 2dB off (because they used the wrong kind of meter years ago), so ref is technically 83dB SPL, and maximum peak is 103dB. But what's 2dB among friends and industry experts?
Haha I saw that thread. That type of pedantry is exactly why I love this forum so much. I'm referring to the digital side. So 0db would be loudest and the 85db tone should be scaled -20 relative to that. In analogue you might not hit 105 in actuality due to power compression and what have you. Is reference level really 85db SPL? As an average, not as the test tone. I was talking specifically about the decibels your ears would experience listening to a movie. In which case from what I can find it appears the goal is 75db leq(A) long term average on a system calibrated for 85db tone scaled -20 digital (Reference Level). (feel free to replace 85 with 83db spl in this paragraph )

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-5 relative to what? What are you setting anyway? BTW, what you want to do is design so you can reproduce a 0dBFS signal across the audio band without distortion, relative to reference level. You don't design for crest factor, you design for maximum, and let the crest fall wherever it is.
-5 setting on the receiver meaning theoretical max would be 100db. That would put 10 feet placement as the limit for 250w peaks. (Once again a disclaimer that I realize all these numbers are "fluff" since I'm having to base it off "recommended amp power" and real world program content is varied)

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The splice is one of the dodgy spots.

And let me say, it's refreshing to hear from someone your age that is so engaged in this hobby. That's not typical, and most of us could easily be your dad or grandfather.
It seemed like a good investment for us as we always found concerts/movies/clubs too loud/distorted/uneven-response. Now we have total control, can have our own snacks, and get a much better sound quality. Tickets to 1 event can be $200. If we get 10 years out of this system, and use it daily, that's pretty darn good value in my book.

With the trend towards sound bars and -4db rms EDM hopefully enough people in my generation convert eventually to proper setups. I understand the current mastering trend is seeing how the song sounds on iPod earbuds. It would be a shame if some audio companies died due to lack of demand.

I've ruined modern music for my wife now too. With replay gain, playing a modern song after Steven Wilson, Classical, etc. is eye opening. Completely lacking in impact and sounds grating on the ears.

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Originally Posted by m. zillch View Post
Remember how that Allison CD-9 speaker I linked to, the one that has pretty much the only meaningful power handling spec, a whole paragraph, which mentioned it was still comfortable with most frequencies at even 750 watts, if for only a tenth of a second? That's a peak. Speakers are usually quite forgiving of high level input if just for a peak. It is sustained, high level, not very dynamic music [highly compressed] which kills them.

Speakers blow up for only two reasons...

People who listen to classical music, even loud Mahler, are the least likely to damage their speakers, in my experience. They hear the onset of distortion, back down on the volume knob, and then are OK. No damage unless the volume knob is in another room and it took them a minute to run back to the living room to turn it down.

The main groups who get into trouble are...

See, if you don't know the song you wouldn't know if the sound you are hearing is "correct" or due to your excessive use of your volume knob! That's the danger. Distortion masks distortion.

On a side note, I remember when this album came out one reviewer said, "I can get better sounds out of my sink's garbage disposal". I think he was referring to the part I was highlighting. Haha. [I like this song though.]
I missed clicking on the manual the first read through. Even the impedance is better defined. They must be the one of the only companies to do that. I'm well aware of Klipsch and their 98db efficiency claims. (On their modern speakers not the old horns)

I appreciate the description of the types of damage that can occur. It's reassuring to know that I should hear distortion in the classical music before anything negative happens. Great write up!


Thanks again everyone! I think my question has been answered as well as it can be. (Especially given that the speaker manual isn't like the Allison)
It seems to me getting a power amp for the front 3 might still be a good idea. Just because my receiver is dealing with 7 speakers, and if the review is correct they are 5ohm nominal, ~3ohm minimum. I understand modern receivers don't do well with higher current draw.

Next on the agenda is room treatment!

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Haha I saw that thread. I'm referring to the digital side. So 0db would be loudest and the 85db tone should be scaled -20 relative to that.
Yes, but reference (85/83/pick one and live with it) an acoustic reference level you measure in the LP. That makes it very analog, and subject to the type of analog meter used.
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In analogue you might not hit 105 in actuality due to power compression and what have you.
"Power compression"...another subject of myth and conjecture. Don't count on it.
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Is reference level really 85db SPL? As an average, not as the test tone.
Yes, it's really 85/83dB SPL, and as measured only with a test signal. Otherwise, "reference" has very little meaning. Having it sets up system gains, but doesn't guarantee you'll actually have a lot of audio at 85dB SPL playing any given program material.
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I was talking specifically about the decibels your ears would experience listening to a movie. In which case from what I can find it appears the goal is 75db leq(A) long term average on a system calibrated for 85db tone scaled -20 digital (Reference Level). (feel free to replace 85 with 83db spl in this paragraph )
Don't get too wound up in dailnorm. The average you get is still the result of the mix, and all the "art" that goes into that. (note the quotes)
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-5 setting on the receiver meaning theoretical max would be 100db. That would put 10 feet placement as the limit for 250w peaks. (Once again a disclaimer that I realize all these numbers are "fluff" since I'm having to base it off "recommended amp power" and real world program content is varied)
Theory and practice don't always match. You can calculate it to death, there are still variables you don't know about. It's only good to get you in the ballpark. Wait until you deal with acoustics, if you like variables. I had a client who spent days calculating even room mode distribution with spreadsheets, tuning it by math. He built the room, it wasn't much like he figured. The variable was, the calculations were based on highly reflective wall composition, which real walls aren't.

I don't obsess. Just about every speaker designed for home theater, and any respectable AVR will provide enough volume in the average room for anyone but the critically deaf.
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It seems to me getting a power amp for the front 3 might still be a good idea. Just because my receiver is dealing with 7 speakers, and if the review is correct they are 5ohm nominal, ~3ohm minimum. I understand modern receivers don't do well with higher current draw.
There's a whole lot more to it that just that. Try the AVR alone first. And where's this impedance curve? Can't find it. Just because it dips to 3 ohms, or averages 5, doesn't mean an AVR can't drive them.

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Just about every speaker designed for home theater, and any respectable AVR will provide enough volume in the average room for anyone but the critically deaf.
There's a whole lot more to it that just that. Try the AVR alone first.
Agreed. Modern AVR's have more power than ever and thanks to the fact that we off load the burden of the deep bass, the hardest most power bobbling part of the music off to the powered sub, even modestly priced AVRs usually have plenty of juice.

There's a trend for lots of audio hobbyists to beef up at least the front channels via outboard amps connected to the AVR's preouts [I hear this is mostly an American thing] quite needlessly, in fact when you crunch the numbers their claims of "Now that I have the extra power, 50-60 more watts, I can really feel the added punch and effortless ability to more loudly reproduce my 2ch music, especially the momentary, transient peaks" usually amounts to a piddly 1dB higher maximum output SPL, two or so, tops.

Here's an example, also by way of another quiz. How much louder can a top of the line Yamaha RX-A3050 [ 9 x 150 W/ch (8 ohms, 0.06% THD) ~$2,000] play in stereo compared to their more modest RX-V677 [90 W per channel, 7ch, 8 ohms, 20 Hz-20 kHz, 0.09% THD, 2-ch driven ~$330 street]?

A) Gobs and gobs louder, night and day
B) about 2.2 dB louder for the extra $1670, not double, but rather six times the price

Now walk over to your existing receiver, hopefully with a volume knob showing dB, and turn up the music 2.2 dB. Is that added boost worth six times the smaller AVR's price, or an additional $1670?
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Text...
I was just throwing out words with the power compression. I haven't read anything about that area of speakers anyway.

Yes reference level is analog defined, I was just making an argument based on the digital side which I can observe, that listening at reference level is potentially not in the hearing damage range based on long term levels. You're right, I'll have to look at an actual file, instead of basing it off the dolby encoder dialnorm specs. Either way that's all sort of offtopic!

And yea, the analog side is much harder to deal with. That must have frustrated your customer. It's why for my next system the idea of FIR digital filters vs passive crossovers seems so appealing. Analog has many more unknown variables.

No phase graph I can find. I'm basing it solely off the one review which could be wrong. I'll have to figure out how to take measurements for myself. Bug my engineering buddy for equipment.

"Impedance measurements (also performed with the Clio FW) indicate that these speakers may be a little tough to drive for inexpensive receivers. All have a fairly low measured nominal impedance of 5 ohms. The tower is the toughest load, hitting a minimum impedance of 2.8 ohms at a low frequency of 66 Hz with a fairly reactive phase angle of -32°... The center and surround present a somewhat easier load. The center hits minimum impedance of 3.5 ohms at 9.5 kHz/+4° phase angle, while the surround’s minimum is 4.0 ohms at 7.2 kHz/+1° phase angle."

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Agreed. Modern AVR's have more power than ever and thanks to the fact that we off load the burden of the deep bass, the hardest most power bobbling part of the music off to the powered sub, even modestly priced AVRs usually have plenty of juice.

There's a trend for lots of audio hobbyists to beef up at least the front channels via outboard amps connected to the AVR's preouts [I hear this is mostly an American thing] quite needlessly, in fact when you crunch the numbers their claims of "Now that I have the extra power, 50-60 more watts, I can really feel the added punch and effortless ability to more loudly reproduce my 2ch music, especially the momentary, transient peaks" usually amounts to a piddly 1dB higher maximum output SPL, two or so, tops.

Here's an example, also by way of another quiz. How much louder can a top of the line Yamaha RX-A3050 [ 9 x 150 W/ch (8 ohms, 0.06% THD) ~$2,000] play in stereo compared to their more modest RX-V677 [90 W per channel, 7ch, 8 ohms, 20 Hz-20 kHz, 0.09% THD, 2-ch driven ~$330 street]?

A) Gobs and gobs louder, night and day
B) about 2.2 dB louder for the extra $1670, not double, but rather six times the price

Now walk over to your existing receiver, hopefully with a volume knob showing dB, and turn up the music 2.2 dB. Is that added boost worth six times the smaller AVR's price, or an additional $1670?

When I searched before I was unable to find an answer for how much load a high pass would take off. From my memory I was told a negligible amount and it only helped for speaker distortion. Previously I was thinking that highpassing at 100hz, say, would take some current requirement off the amp as normally the bass region is lowest impedance in my understanding.

The comment about getting an amp was not something I'm considering doing right now. I shouldn't have muddied the conversation. And yes, I realize that 120w vs 80w amp is negligible. You quickly go to 1000w to 2000w only being 3db gain, which is why high efficiency speakers seem so much better. In my current situation, going from 70w to 250w would be over 5db, which isn't nothing. Providing my speakers could handle it of course. That's why I was mentioning the pro amp, or something used. It would have to be under $500 to be even considered. My outlook when buying the equipment was completely agreeing with your point. Previously I used a 20w class D amp. I just also can't discount the fact that I don't have the real life experience to compare for sure. (Given I understand receivers are not made to handle low impedance and cap out at 8ohm recommended)
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Originally Posted by boifido View Post
When I searched before I was unable to find an answer for how much load a high pass would take off. From my memory I was told a negligible amount and it only helped for speaker distortion.
I helps in several ways. The amp runs cooler and has less burden on it but the music content matters. If all you listen to is flute solos, it won't make any difference at all, however if you listen to music with strong, deep bass, then it matters. Not a ton, but it matters.

If the stars are aligned perfectly in your favor, and you play content of hand selected music with a spectral content to show off how much greater SPL increase you can get, assume you'd get an effective boost of around 1.8 to 2 dB, or 3 dB at the very most in a theoretically perfect world [which would seem as if you had doubled your amp's wattage]. In real world use, with average music, it may be very little (90% of the time when there is no loud, low bass), say 1 dB or even less, which you might not even notice unless a technician using instrumentation dialed in a specific torture test that just barely started to strain the weaker setup audibly, yet the "stronger" one was still, just barely, able to keep up without audible strain.

Quote:
(Given I understand receivers are not made to handle low impedance and cap out at 8ohm recommended)
Not all, but many receivers don't make claims that they can do 4 ohm loads, yet in truth they can. See the problem is if you claim you can do it then your design has to go through UL/CSA testing at that stated load and it may generate so much heat that without springing for extra cooling fans, which ups the cost of production, you'll fail the test, on safety grounds, and not get UL/CSA certification.

Here's an example of a unit which has pretty good 4 ohm capability yet the maker claims 4 ohms is "not sanctioned", so they never had to undergo heat testing at that load and therefor skated through UL testing inexpensively [no internal cooling fan needed]: http://www.soundandvision.com/conten...ssE9c6IpC9a.97

In A/V reproduction accuracy, there is no concept of "accounting for taste". We don't "pick" the level of bass, etc., any more than we pick the ending of a play. High fidelity means an unmodified, neutral, exact copy (or "reproduction") of the original artist's tonal balance, timing, dynamics, etc..
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