How much power is really needed?

[NBPK402]

 

Just wondering what yall see out there on how much you really need? 

About the same, ~5 watts, and almost entirely in the sub channel.  ~100mV across the L,C, & R at wide-open throttle. 

 

The discussion between amps and "How much?" often falls short because what's really at play is often times not power delivery, but rather the transient behavior of each device. Almost no data, from any manufacturer, is ever provided in that regard. Even fewer people have the tools, knowledge, and time to investigate that, in particular case by case.

 

There's a lot more to it than just raw, calculated power numbers.

 

Curiosity makes me ask (great discussion for learning)... since you have measured... If a 5 wpch amp will get you to reference levels continuously (which we only need for peaks).... How much more power is needed for transients? Would transients be covered with the 5wpc reaching peaks, or is something else coming in to play? 

[homeskizzle]

 

Just wondering what yall see out there on how much you really need? 

About the same, ~5 watts, and almost entirely in the sub channel.  ~100mV across the L,C, & R at wide-open throttle. 

 

The discussion between amps and "How much?" often falls short because what's really at play is often times not power delivery, but rather the transient behavior of each device. Almost no data, from any manufacturer, is ever provided in that regard. Even fewer people have the tools, knowledge, and time to investigate that, in particular case by case.

 

There's a lot more to it than just raw, calculated power numbers.

 

Oh I agree Quiet_Hollow! That's where my own particular experience changes and I'll be the first to admit it. There is more than just numbers - it's about the experience. 

 

I was just curious to know how much power I was actually using. For me - the audio experience is still amazing and powerful, but I just don't need as much power as I thought I needed. I haven't changed anything in the way I operate my system - but wanted to share my findings. 

[garyrc]

 

Just wondering what yall see out there on how much you really need? 

About the same, ~5 watts, and almost entirely in the sub channel.  ~100mV across the L,C, & R at wide-open throttle. 

 

The discussion between amps and "How much?" often falls short because what's really at play is often times not power delivery, but rather the transient behavior of each device. Almost no data, from any manufacturer, is ever provided in that regard. Even fewer people have the tools, knowledge, and time to investigate that, in particular case by case.

 

There's a lot more to it than just raw, calculated power numbers.

 

 

I agree.  The amount of power you need is enough to cover transients.  Power consumption, long term, is another animal.

[pite]

Klipsch speakers range from 97dB to 105dB, which is way more efficient than any respected brand available on the market. If designed correctly, horn based/loaded speakers are inherently efficient. I'd wrote a white paper couple of years ago explaining how it works and can post here or create a thread for fellow Klipschers if interested.

[Quiet_Hollow]

How much more power is needed for transients?

 Arguably none...once again, so long as the system isn't doing something else with the signal. There's quite a wide margin for error in the chain than simply not making enough power.

 

Would transients be covered with the 5wpc reaching peaks, or is something else coming in to play?

Yes and yes...

 

In regard to something else coming into play, I use a Panasonic XR to drive my system. There's two caveats to using this thing for ultimate HT sound:

 

1. It doesn't have the chipset to digest the HD (ie. un-compressed) bitstreams on Blu-Rays. It can only handle the lossy core. So it ends up sounding a little more crispy than it's capable of, unless the source has a 5.1 un-compressed PCM audio track available. Regardless of that, the unit falls prey to...

 

2. The high pass filter has less than stellar transient performance. If it tries to pass a full-scale signal, like a low freq test tone, it kicks off a whole bunch of high-frequency noise in the process (IMD). This makes for bass transients, when played back at spirited levels, sounding much more harsh than they should be. Especially if the source track is clipped to begin with. 

 

So there we go. Two things that make the unit sound harsh in practice that are completely unrelated to power requirements or capability. 

 

Power consumption, long term, is another animal.

Also agreed.

 

That, and we can watch everyone turn ghost white while somebody tries to investigate the actual, intended duty cycle of their product.

[garyrc]

If a 5 wpch amp will get you to reference levels continuously (which we only need for peaks).... How much more power is needed for transients?

 

There are peaks (transients), then there are peaks (transients).  

 

In my former house, with a Yamaha power amp that had what they claimed was a peak reading meter, and Klipschorns (some of the world's most efficient home speakers), the power output was often less than ~ 1 watt, but would read 6.3 watts fairly often on peaks, and, occasionally, just below 25 watts on climaxes like that of Fanfare for the Common Man.  A klipsch forum poster of a few years ago determined that a rim-shot would require more power than almost any amp/speaker combo could provide, if it was recorded fairly close up. 

Edited March 6, 2015 by garyrc

[NBPK402]

 

 

Just wondering what yall see out there on how much you really need? 

About the same, ~5 watts, and almost entirely in the sub channel.  ~100mV across the L,C, & R at wide-open throttle. 

 

The discussion between amps and "How much?" often falls short because what's really at play is often times not power delivery, but rather the transient behavior of each device. Almost no data, from any manufacturer, is ever provided in that regard. Even fewer people have the tools, knowledge, and time to investigate that, in particular case by case.

 

There's a lot more to it than just raw, calculated power numbers.

 

 

I agree.  The amount of power you need is enough to cover transients.  Power consumption, long term, is another animal.

 

Correct me if I am wrong please, Power consumption long term would be less, correct?

[garyrc]

 

 

 

Just wondering what yall see out there on how much you really need? 

About the same, ~5 watts, and almost entirely in the sub channel.  ~100mV across the L,C, & R at wide-open throttle. 

 

The discussion between amps and "How much?" often falls short because what's really at play is often times not power delivery, but rather the transient behavior of each device. Almost no data, from any manufacturer, is ever provided in that regard. Even fewer people have the tools, knowledge, and time to investigate that, in particular case by case.

 

There's a lot more to it than just raw, calculated power numbers.

 

 

I agree.  The amount of power you need is enough to cover transients.  Power consumption, long term, is another animal.

 

Correct me if I am wrong please, Power consumption long term would be less, correct?

 

 

I think so. 

 

Some amps can squeeze out quite a bit of peak power for a brief moment.  I used to think that they would put out 2 times their rated power output (3dB), because that's the way manufacturers' peak power specs tend to read, but it may depend on how long the peak is.   Klipsch and Keele, in a 1977 Dope from Hope on SPL said that good amps can pass brief peaks 10 dB higher than their rated power without clipping, but they didn't say how brief.  It happens that a 10 dB increase is about 10 times the power in watts!  That seem like lot to me, but I'm not an engineer, and they both were.

 

The power needed for a peak of a given SPL depends on the loudspeaker, the room size, the distance at which the SPL of the peak is measured, etc.  The loudest brief peaks I've heard in a home required a bit less than 25 watts each into each of two Klipschorns, if my old Yamaha power amp "peak reading meter" really was a peak reading meter.  If I was running two B&W 801Fs instead of Khorns, it would have required something like 2,500 watts into each channel for the brief moments of those peaks.  That doesn't mean I would have required a 2,500 w.p.c. power amp, though.  If Klipsch and Keele were right, I might have been able to limp along with a 250 w.p.c. amp.

 

McIntosh used to make a three chassis power amp that was about 2,000 watts rated power.  They advertized that it could put out 8,000 watt brief peaks.  They advised turning on their amp first, without any other components on, then (after charge up?), turning the other components on one by one.

[babadono]

Remember a 10dB increase in sound intensity most would judge as TWICE as loud, but 10dB more out of your amp is 10 times more power. To double the intensity again would require 100 times the power.

Headroom is a good thing.

[Ski Bum]

For those without a multimeter but with an spl meter, try this calculator.  I've found it to be pretty close to actual electrical measurements.  Be sure to select "near a wall" in the speaker placement box, as the calculator seems to produce more accurate results in my experience, and also use real/realistic/conservative sensitivity numbers.  

[garyrc]

For those without a multimeter but with an spl meter, try this calculator.  I've found it to be pretty close to actual electrical measurements.  Be sure to select "near a wall" in the speaker placement box, as the calculator seems to produce more accurate results in my experience, and also use real/realistic/conservative sensitivity numbers.  

 

The calculator is very good, but I disagree with his note later on concerning likely dialog SPL.  I believe that, excluding whispering and shouting, dialog in our HT is between 65 and 80 dB, probably averaging 70 -75, and we play back at about 5 dB below calibrated Reference level (using Audyssey).  He says the dialog level would be "at least 85 - 90 dB" in HTs capable of up to 107 dB at MLP.   Our HT is capable, according to his calculator, of about 120 dB at listening position, but Full Scale at Reference through the center speaker (where almost all of the dialog comes from) would be 105 dB and the filmmakers keep the dialog way below that.  I'll measure the dialog levels tonight when we run Game of Thrones at 5 dB below Reference, and post the results.

Edited March 6, 2015 by garyrc

[garyrc]

O.K., as promised, here are the dialog and other levels in our HT for Game of Thrones (season 4, episode 3 and 4, on Blu-ray) from main listening position, with the main volume set at 5 dB below calibrated Reference level.

 

Dialog (no screaming or whispering):  Center of needle swing 74 to 78 dB.  Range of swing 70 to 81 dB.  Most people on a variety of forums report running at a lower level than our 5 dB below reference.  The author of the calculator mentioned was concerned because he thought movie dialog level for people who have powerful HTs would be "at least 85 - 90 dB," and I guess his reasoning was that dialog runs all the way through most movies, and that would constitute long and dangerous exposure, but I don't think anyone would playback dialog at "at least 85 - 90 dB."

 

Just for comparison, the music and effects in these Thrones episodes ranged up to 102 dB, during the time I was measuring.  Of course, sound of this level was of very short duration.  There were a lot of drums in the score, and for music and effects (unlike for dialog), the subwoofer was involved.   

 

The maximum tolerable levels charts are referring to more or less constant levels at high SPL, not the transients in something as bland as dialog, or even movie music and effects, except in a few movies in which there are long sequences with very high dB levels like Transformers, or Pacific Rim.  For Rock/Metal concerts, no guarantees. 

 

I suspect that the mean and standard deviation for dialog level is pretty much the same for all dramatic TV productions and movies made in the last few years.  

[AaronH]

This is a post from the President of Emotiva. 

 

I want people to share their experiences and opinions here on the Lounge. I don't care what they talk about product wise. You like another product? Cool. We're not worried. We welcome comparison. If some guys think their AVR is all they need, well that's fine. Maybe it fits their needs and their budget. Some people do not like to feel like their decisions and opinions are being challenged. They get angry and defensive. Maybe that's the core of the issue there... All you have to do here is be civil and respectful... opinionated is fine. No taunting!!

Clearly they have not heard a system with real headroom. Headroom is what having big amps is all about; not playing as loud is you can stand it!

I'm thinking about doing a tech article on this very subject. I'd like to show how a typical "brand X" receiver behaves in a real world situation with typical speakers in an average listen room. You will be amazed to see how quickly you can run out of gas. I can drive an XPA-5 into mild clip quite easily with the right type of program material, so imagine what a receiver that makes less than half of its rated power with all channels drive will do.

Headroom is all about clarity, resolution and maintaining dynamics. You will be amazed at how much more you can hear when your system is not pushed to it's dynamic limits. power wise.

Stand by...

In the meantime, have fun kids!
Cheers,
Big Dan

[Paducah Home Theater]

Another thing that people don't think about when buying an am is... Amps are designed to run at a certain power (as an example say arbitrarily 2/3 of max), when you buy a large amp, and are say at 1/3 power you are listening to your amp at a higher distortion than if you had an amp that was matched better to your setup.

How much distortion are we talking about? I didn't realize this was an issue. They don't seem to make external low power home theater amps though. You get a 5-7 channel amp and it's nearly always going to be 125-200 watts per channel. Even with inefficient speakers and playing at pretty high levels you're not going to constantly be running it at 2/3 power.

[Paducah Home Theater]

Klipsch speakers range from 97dB to 105dB, which is way more efficient than any respected brand available on the market.

I'm sure it's more than usual but unfortunately the posted numbers seem to be bloated and exaggerated though. Good examples:

http://www.soundandvision.com/content/klipsch-thx-ultra2-speaker-system-ht-labs-measures

Measured at 92 db. 97 is what is claimed.

http://www.soundandvision.com/content/klipsch-reference-rf-83-speaker-system-ht-labs-measures

94 vs. 100 claimed.

For comparison, B&W CM9's measured at 92.5 from the same lab. Martin Logan Motion 40's are 91. Paradigm Monitor 11, Series v.5 were 93.5.

When you see 97 db on a KL-650-THX vs. 91 on a Martin Logan motion 40, 6 db sounds impressive but the same lab measured only 1 db difference, which I don't think you can even hear the difference.

Edited March 6, 2015 by MetropolisLakeOutfitters

[Ski Bum]

 

Another thing that people don't think about when buying an am is... Amps are designed to run at a certain power (as an example say arbitrarily 2/3 of max), when you buy a large amp, and are say at 1/3 power you are listening to your amp at a higher distortion than if you had an amp that was matched better to your setup.

How much distortion are we talking about? I didn't realize this was an issue. They don't seem to make external low power home theater amps though. You get a 5-7 channel amp and it's nearly always going to be 125-200 watts per channel. Even with inefficient speakers and playing at pretty high levels you're not going to constantly be running it at 2/3 power.

 

 

Don't get lost in the weeds.  All amps, even class A types, exhibit rising noise at diminishing power levels, as the inherent noise of the component parts starts to dominate thd/noise measurements at such micro-watt levels.  Fortunately, that's only a problem if you're running genuinely high sensitivity speakers (think active rigs with fully unrestrained cd/horns).  Once you go from micro watts to milliwatts, as would happen with less sensitive speakers, such potential problems are already in the rear-view mirror so to speak.

 

 

Klipsch speakers range from 97dB to 105dB, which is way more efficient than any respected brand available on the market.

I'm sure it's more than usual but unfortunately the posted numbers seem to be bloated and exaggerated though. Good examples:

http://www.soundandvision.com/content/klipsch-thx-ultra2-speaker-system-ht-labs-measures

Measured at 92 db. 97 is what is claimed.

http://www.soundandvision.com/content/klipsch-reference-rf-83-speaker-system-ht-labs-measures

94 vs. 100 claimed.

For comparison, B&W CM9's measured at 92.5 from the same lab. Martin Logan Motion 40's are 91. Paradigm Monitor 11, Series v.5 were 93.5.

 

 

This is exactly why I suggested "real/realistic/conservative" sensitivity numbers for that power calculator.  Forte II are ~95.5 db/w/m, not 99 as claimed.  It's pretty much that way across the board with Klipsch, at least the ones intended for domestic use.

[NBPK402]

 

Another thing that people don't think about when buying an am is... Amps are designed to run at a certain power (as an example say arbitrarily 2/3 of max), when you buy a large amp, and are say at 1/3 power you are listening to your amp at a higher distortion than if you had an amp that was matched better to your setup.

How much distortion are we talking about? I didn't realize this was an issue. They don't seem to make external low power home theater amps though. You get a 5-7 channel amp and it's nearly always going to be 125-200 watts per channel. Even with inefficient speakers and playing at pretty high levels you're not going to constantly be running it at 2/3 power.

 

A friend of mine works for a Company that designs and builds amps and he told me I should have went with smaller amps because of the efficiency of my speakers.  My bass bins are running around 1 watt on peaks with a 250wpc amp, and my horns are in the less than 100th of a watt with my 25wpc amps. One of the advantages of horns is low distortion and I hate to see that advantage go to waste by adding distortion back by getting too big of an amp. I too looked for low power amps for multiple channels and couldn't find any... I am assuming that they are not out there because most people do not have that efficient of a speaker, and people think more power is better.

[Paducah Home Theater]

Another thing that people don't think about when buying an am is... Amps are designed to run at a certain power (as an example say arbitrarily 2/3 of max), when you buy a large amp, and are say at 1/3 power you are listening to your amp at a higher distortion than if you had an amp that was matched better to your setup.

How much distortion are we talking about? I didn't realize this was an issue. They don't seem to make external low power home theater amps though. You get a 5-7 channel amp and it's nearly always going to be 125-200 watts per channel. Even with inefficient speakers and playing at pretty high levels you're not going to constantly be running it at 2/3 power.

A friend of mine works for a Company that designs and builds amps and he told me I should have went with smaller amps because of the efficiency of my speakers.  My bass bins are running around 1 watt on peaks with a 250wpc amp, and my horns are in the less than 100th of a watt with my 25wpc amps. One of the advantages of horns is low distortion and I hate to see that advantage go to waste by adding distortion back by getting too big of an amp. I too looked for low power amps for multiple channels and couldn't find any... I am assuming that they are not out there because most people do not have that efficient of a speaker, and people think more power is better.

Tube amps for guitars are definitely like that but I have never heard of it being an issue with solid state home theater amps. With guitar amps I'd take a small tube amp that is almost wide open over a huge one that is barely running any day. Standard amplifier logic is the exact opposite it seems.

[garyrc]

 

 

Another thing that people don't think about when buying an am is... Amps are designed to run at a certain power (as an example say arbitrarily 2/3 of max), when you buy a large amp, and are say at 1/3 power you are listening to your amp at a higher distortion than if you had an amp that was matched better to your setup.

How much distortion are we talking about? I didn't realize this was an issue. They don't seem to make external low power home theater amps though. You get a 5-7 channel amp and it's nearly always going to be 125-200 watts per channel. Even with inefficient speakers and playing at pretty high levels you're not going to constantly be running it at 2/3 power.

 

A friend of mine works for a Company that designs and builds amps and he told me I should have went with smaller amps because of the efficiency of my speakers.  My bass bins are running around 1 watt on peaks with a 250wpc amp, and my horns are in the less than 100th of a watt with my 25wpc amps. One of the advantages of horns is low distortion and I hate to see that advantage go to waste by adding distortion back by getting too big of an amp. I too looked for low power amps for multiple channels and couldn't find any... I am assuming that they are not out there because most people do not have that efficient of a speaker, and people think more power is better.

 

Is he a designer?  An engineer?

 

I don't know, but I've heard that some amps have significantly higher distortion at very low output, and others don't.   Some early solid state amps (late '60s) had that reputation.  A few amp manuals have distortion graphs (e.g., my old Luxman).  I've also heard that THD+Noise graphs can be misleading.  I would hate to give up headroom.  I'm more or less in the dark about this.

[pite]

It's a good point, to have a decent discussions and not to be hostile.

 

That said, Klipsch speakers are inherently efficient, so one doesn't need to drive them hard in order to achieve desire low to medium SPL to the comparable speakers which are typically 87-90 dB efficient. I can speak of my own experience with RF-7 II, RF-83, RC-64 II and Palladium P-39F, which are efficient and not-in-your-face i.e. doesn't need too much of power to drive them for low to medium SPL. Now, if you want to drive them to highest SPL that these speakers can produce then you need that clean power. Most probably, if you need to drive them these loud in your home enviornment then probably one will be on the way to become deaf or is deaf - lol !!

 

Good amp with 0.05% or lower THD for low to medium SPL, the available 100-150w RMS power should be sufficient. It won't "Rock Your World", but for that one can use subwoofer.

 

If it's a high-distortion AVR or AMP then it's more like "garbage in - garbage out". But with decent amplifier, I'm happy to be proved wrong at low to medium SPL. I've auditoned quite a few high end AVR and seperates, but haven't heard so far the difference with high end Klipshes (no experience with Heritage line) - probably, I'm NOT audiophile !!!