How Many Watts am I using?

[yepimonfire]

A -20dB reading on the volume would be 65 dB average level, 85 dB peaks. (10dB more for the LFE channel). That Crown calculator is more suited to venue use than home....

My mistake. Got basic math wrong lol. And yes it is, there's a peak spl calculator out there somewhere but I can't find the link.

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[lovinthehd]

My mistake. Got basic math wrong lol. And yes it is, there's a peak spl calculator out there somewhere but I can't find the link.

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The peak spl calculator link is in post # 6.

 

[yepimonfire]

If you can experiment with speaker placement, I strongly recommend it. Mark the present location and move each one in small increments to find their sweet spot. I did that a couple of years ago and it made a huge difference in the sound of my system, the apparent location of vocals and instruments, the frequency response and it actually sounds better at low SPL than it did at ANY level before I did this.

At the moment, the Pandora station I'm listening to is playing 'Girl From The North Country' from Joe Cocker's Mad Dogs & Englishmen and I would be very surprised if my amp is pounding it out at more than 1/2 Watt/channel but the details are far from lost. Another interesting thing is that the high and low frequencies don't lack anything- the current song is 'Sucker Row', by Mark Knopfler and the cymbals & bass guitar come through very nicely, as do the electric guitars (not a loud song), drums and vocals. The next song is 'The Lucky Man' by Allison Krauss & Union Station- everything is crystal clear.

I find the equilateral triangle rule doesn't work well with a lot of speakers, especially klipsch, the sound thins and imaging becomes amorphous.

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[PENG]

A -20dB reading on the volume would be 65 dB average level, 85 dB peaks. (10dB more for the LFE channel). That Crown calculator is more suited to venue use than home....

I told you.

 

[PENG]

The easiest way is to assume your avr is only going to put out 70% of its claimed 2ch power ACD. Figure up your speakers sensitivity rating for each set, then figure out how loud you listen. Assuming you've properly calibrated your speakers to all play at 75dB at the listening position, if you've got a receiver with a relative volume control (measured in minus dB), subtract that from 105dB, so say you watch movies at -20dB, that'd be 95dB. If you don't have a relative volume control, just turn it to what you normally listen at, and use rew to generate pink noise at -3dBfs, then measure that using a C weighted spl meter at the main listening position. That's your maximum peak spl requirement. Once you've figured that out, head over here and plug the numbers in http://www.crownaudio.com/en-US/tools/calculators#amp_power_required

You'll need to do that for each speaker set if they're different sensitivity ratings and distances.

You'll either find out you need a whole lot less power than you thought or a whole lot more. This is one reason I suggest using pro audio amps if your receiver isn't up to snuff. Adding a 150w amplifier in place of the internal 100w amp is going to give you a lousy 1.5dB gain. Some people rationalize that adding an amplifier to the fronts takes a load of the receiver to handle the center and surrounds, and while this is true, you're still limited to that maximum 2ch driven. You're not gonna get more than that, even if the power supply is up to snuff, the voltage rails can't supply more than the maximum value their built for without clipping.

If you're running 3-6dB below what you need, you should probably invest in a 200-400w amp. If you're at the higher end of that range, it might be time for some bigger more sensitive speakers. A set of bookshelves may be rated at 85dB, while their floor standing counterparts might be 89db, or even 91dB, in addition, they can handle the extra power for peaks without frying.

A huge misconception is that you only need to focus on the front two channels since they supposedly carry the weight, that's completely false. I've pulled the audio tracks off of blu rays for several movies and opened them up in Reaper to see how much content is in each channel and at what volume. Even in dramas and comedies, the surrounds are doing just as much work as the front left and right for at least 80% of the time, if not for effects, for music, the center channel is doing about 60% of the entire soundtrack, including full range effects, not just dialogue. If you can find the space and have the budget, I strongly suggest making sure your surrounds are just as competent and large as your fronts, obviously using a tower speaker as a center channel isn't practical in most cases, so just get the biggest one you can find to match the power of your fronts.

The hard truth is unless you're using a budget receiver rated at 50wpc, upgrading your 100wpc receiver for a 120wpc receiver isn't going to help if you're really hurting for power.





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Wow, I normally agree with you but not this time, not even close, may be 10%..

 

[PENG]

my speakers are supposed to be 8 ohms. I don't know anything different.
My new Salks are going to come in between 4 and 6 ohms and I will cross that bridge when they arrive.

When I have a moment I can get you the conversion figures from my spreadsheet, at 0.25 ohm intervals, that should be close enough.

 

[PENG]

I have located a nice digital Fluke Meter. It may take me a week or so to swing by and borrow it. I will then try this again with a 1Khz tone, a suitable db listening level, and a digital meter. I will see if we can't refine the number just a bit , or at least come up with a process that the brain trust thinks is worthy of the effort. I think the 1khz tone is doable and helps, and the digital meter will help a bit too.

I will leave the slide rules in my display case. I try never to use lube unless I'm really, really serious about getting the wood to move.....................

What model number? If you have the 87v digital meter, it can handle high frequencies and remain accurate within a few %. It is also true rms so no problem even with some music signal, just suffer further on accuracy that's all. The multi meter is easier to use and interpret than an oscilloscope. By the way, slide rules can do just about anything but gets way difficult for something like this.

 

[highfigh]

I find the equilateral triangle rule doesn't work well with a lot of speakers, especially klipsch, the sound thins and imaging becomes amorphous.

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I usually shoot for Isosceles, with the altitude roughly 50% higher than it would be if it was equilateral, the distance between the speakers remaining constant. I have written about a system I listened to that really should sound much better than it did, given the price of the equipment and the size/shape of the room. The speakers aren't where they should be and there's really no middle to the sound- a lot of vocals should come from dead center and with this system, almost nothing.

I prefer textile dome tweeters and that's what I usually sell. Occasionally, I'll use a different material if the application warrants it (like outdoors), but it's rare that I use metal domes and when I use some kind of horn, it's because the space is large and I'm trying to prevent sound reflection from the walls- in that kind of application, separation & imaging aren't important because it's a distributed audio system that requires even coverage, not stereo. I can't comment about newer Klipsch speakers since I haven't listened to them in a long time.

 

[highfigh]

Again, the sensitivity for 1W and 2.83V will not be the same unless the load impedance is 8 ohms.

Right, but if people knew that they only need to use P=E²/R, this wouldn't be an issue. That way, 1W could still be used and nobody would care about the impedance not matching the old typical impedance of 8 Ohms.

 

[highfigh]

I have located a nice digital Fluke Meter. It may take me a week or so to swing by and borrow it. I will then try this again with a 1Khz tone, a suitable db listening level, and a digital meter. I will see if we can't refine the number just a bit , or at least come up with a process that the brain trust thinks is worthy of the effort. I think the 1khz tone is doable and helps, and the digital meter will help a bit too.

I will leave the slide rules in my display case. I try never to use lube unless I'm really, really serious about getting the wood to move.....................

Mahogany, or Bamboo? My first one is plastic and yes, I know exactly where it is, but I haven't used it since high school. I thought I had another one, but it's nowhere to be found- it was bamboo & ivory.

 

[Verdinut]

Again, the sensitivity for 1W and 2.83V will not be the same unless the load impedance is 8 ohms.

Wouldn't it be better if all manufacturers were honest when publishing the specs, and quoted apart from the nominal impedance, the lowest impedance reading with the corresponding frequency above the fs of the driver? As you know, a low impedance at a low frequency is quite more critical for an amplifier than if it occurs above 500 Hz.

I think that this would simplify matters to some extent, and someone would know more about the feasibility of trustfully using an amplifier with a certain transducer.

 

[Verdinut]

If you ever need a reasonably-priced 6.5", look at their HDS-P830874- I'm using them in 2-1/2 way towers and they work extremely well.

SB Acoustics have very good transducers too. I installed some SB15MFC30-8 (5 inch mid-bass drivers) in a pair of 3-way speaker enclosures with excellent results.
Here is the link: http://www.sbacoustics.com/index.php/products/midwoofers/mfc/5-sb15mfc30-8/

They also have a smooth response and are very well built. They are also very affordable and worth considering for future building projects.

 

[Bucknekked]

Mahogany, or Bamboo? My first one is plastic and yes, I know exactly where it is, but I haven't used it since high school. I thought I had another one, but it's nowhere to be found- it was bamboo & ivory.

I have slide rules in various flavors of wood, aluminum, plastic and whatever else they made slide rules with. I have a lovely loadmaster slide rule for a DC3. The loadmaster used the slide rule to calculate load weights and positions on a DC3 cargo plane. Very interesting application. I also think I had (have) an artillery masters slide rule: yep, lobbing them shells. Lots of specialty ones that I have traded off over the years. I also have one in cyrillic: Russian. I need to go check and see if there's one for audio. There were audio nerds back in the day so I won't be surprisded if I find one

 

[Bucknekked]

I usually shoot for Isosceles, with the altitude roughly 50% higher than it would be if it was equilateral, the distance between the speakers remaining constant. I have written about a system I listened to that really should sound much better than it did, . I can't comment about newer Klipsch speakers since I haven't listened to them in a long time.

I have seen a couple of suggestions for adjusting my speaker placement. Not sure why that came up in this thread, but its a valid suggestion. Here's the deal though, my room is a cube: 10x10x10. If you lay that out on the ground, you will immediately find out many options employed in larger spaces just aren't available here. My Klipsch speakers get boomy and the stereo image gets flat as a pancake if I place them close to the walls. Also, if close to the corners, that boomy bass thing happens.

That drives me away from the back wall and side walls as far as I can get. At the other end of the room, I can only put my listening chair just so far back. If I'm too close to the back, I hit a node where there's no bass at all. Scoot forward a bit, and the bass comes back.

I have taken the "golden triangle" thing and moved the speakers all the way from the corners (not good) in small increments all the way to where they are now and then some non symmetric placement as well. For a small room, there are a lot of variations to try. I spent a fair amount of time, days actually, experimenting with not only placement, but height and toe in (or toe out) as well.

After all that moving and shakin', I ended up where I am now. When I crank back the home theater listening recliner, my feet are actually between the speakers. I have a near perfect (to my humble and care worn ears) stereo sound field that is very pleasing. The downside is the sweet spot is very small.

I hope when the Salks arrive I can do some more experimenting (for sure) and get them pushed back and further apart. The only question will be : do I buy a new amplifier just because I want one?

 

[PENG]

Wouldn't it be better if all manufacturers were honest when publishing the specs, and quoted apart from the nominal impedance, the lowest impedance reading with the corresponding frequency above the fs of the driver? As you know, a low impedance at a low frequency is quite more critical for an amplifier than if it occurs above 500 Hz.

I think that this would simplify matters to some extent, and someone would know more about the feasibility of trustfully using an amplifier with a certain transducer.

Agree, and I want them to provide an impedance vs frequency graph instead of just nominal and minimum. As it is now they can't even agree on the definitions of nominal. Some goes with 1.25 x minimum, some use the DC resistance that's basically the minimum, and others do whatever they like.

At the end of the day, it is still futile because between the sensitivity, room dimensions, seat position, room acoustic, how loud one listen to, and other factors, that often render the impedance factor not the most important in the overall picture.

 

[Bucknekked]

What model number? If you have the 87v digital meter, it can handle high frequencies and remain accurate within a few %. It is also true rms so no problem even with some music signal, just suffer further on accuracy that's all. The multi meter is easier to use and interpret than an oscilloscope. By the way, slide rules can do just about anything but gets way difficult for something like this.

Apparently the guy I can borrow this from thinks all meters are Fluke meters.
The actual meter is a Bluepoint DMSC683A

 

[PENG]

Apparently the guy I can borrow this from thinks all meters are Fluke meters.
The actual meter is a Bluepoint DMSC683A

It's like in the old days all analog meters are AVO, all radios were Grundig or Telefunken, all receivers were Sansui.

That $45 meter is not going to be true rms type. The Fluke 87v cost $500.

 

[Swerd]

Agree, and I want them to provide an impedance vs frequency graph instead of just nominal and minimum. As it is now they can't even agree on the definitions of nominal. Some goes with 1.25 x minimum, some use the DC resistance that's basically the minimum, and others do whatever they like.

At the end of the day, it is still futile because between the sensitivity, room dimensions, seat position, room acoustic, how loud one listen to, and other factors, that often render the impedance factor not the most important in the overall picture.

I agree with PENG. There are so many variables that it can be useless to try to calculate a wattage or even a wattage range.

Another important variable is the time frame. Are you thinking of continuous average power or very short lived high power peaks? The average power in music is what most affects how loud the program sounds to us, while the level of the much-higher peaks is an indication of the amount of dynamics in the music. These higher peaks can be so much higher than the average that power amplifiers are often in danger of clipping. This can happen even when one is not listening at an ear-splitting volume level. This can especially be the case when loudspeakers of low to average power sensitivity are used.

I once saw a demonstration by a guy named Bob Cordell where he measured both continuous average power (over 15 seconds if I remember) and very brief but high power peaks, such as a single snare drum thwack. The difference between the two can be big. An amp which appeared more than adequate if you looked at continuous average power was going into clipping only on those brief moments when high power peaks occurred.

He describes the details on his website http://www.cordellaudio.com/instrumentation/power_level_meter.shtml

I don't propose that Bucknekked go build one of Cordell's meters. But it was after his demonstration that I first began to believe that there might be a good reason to own a big-iron amp. Something I had never considered before.

It does come down to price. I don't know what a reasonable price in $/watt is today. And what is reasonable also depends on a buyer's personal financial state. So there is no simple answer to this question.

 

[Bucknekked]

These higher peaks can be so much higher than the average that power amplifiers are often in danger of clipping. This can happen even when one is not listening at an ear-splitting volume level. This can especially be the case when loudspeakers of low to average power sensitivity are used.

An amp which appeared more than adequate if you looked at continuous average power was going into clipping only on those brief moments when high power peaks occurred.

So there is no simple answer to this question.

Swerd
So you're saying there's a chance I might need a new amplifier? Bless you my son.
I'd love an excuse to add more power. I am not wasteful, but, I am slobbering over more power.
If this exercize justifies a new amp, I know just where I'd go. If it doesn't justify one, but does leave the door open for one, I'm just as happy.

 

[lovinthehd]

There's really only one way to see if the big amp will change much for ya....get one and see. I've gone that route and no longer use my power amps on my avrs (except for subs) but then I'm also not listening at levels I used to. As always, YMMV.