Poultrygeist
Lunatic Member
2.5 watts were plenty for the Zu's. I'm sure I never used a full watt with them.
Why so much Wattage ?
- Thread starter Kevin C
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Ok, ok so a 300, 400 500 watt amp is not unreasonable for someone with 82-90 db speakers that sits 3 feet away from the speakers. Who listens at, at least 80spl with music that has 12 db peaks.
I need a sticky for this....
One of the main points to consider about amplifier power ratings as it relates to sound pressure levels developed by speakers is dynamic range. No one purchases a MC601 or MC1.2Kw to push a continuous 600 watts or 1200 watts into speakers. What the additional power ratings allow an amplifier to deliver is unclipped and undistorted musical peaks. Nearly all well designed speakers thrive on "clean"power but will fail quickly with clipped output from amplifiers. Reserve output power is essential to accurately reproduce the complex wave forms of music.
Music is not a constant tone and volume is not a constant level unless you are amplifying test tones. Music is a continuous stream of peaks and valleys with an average level that is typically consistent. It is not unusual for momentary peaks in a musical performance to rise above the average level by 10 to 12 decibels. These same peaks are often fleeting but require substantial output power to reproduce without clipping the waveforms. We know that for every 3dB rise of input signal the output power will double. Using this information it is easy to understand why an amplifier with plenty of power becomes necessary. As an example lets say you are enjoying a performance at an average level of 25 watts output and a sudden crash of drums or blast of horns generates a 12dB peak above your average level. 3dB above 25 watts would require 50 watts, 6 dB above 25 watts would require 100 watts, 9dB above 25 watts would require 200 watts, and 12dB above 25 watts would require 400 watts of reserve power in order to faithfully reproduce the peak level of 12dB above your average listening level without clipping the output signal. Knowing this, it doesn't seem like such a stretch to have 400, 500, 600, or even 1200 watts on tap.
Another point to take into consideration is almost all speaker manufacturers measure speaker sensitivity at a distance of 1 meter on axis (39.37 inches) directly in front of the speaker. These measurements are most often taken with the speaker placed inside an anechoic chamber where it is completely silent and there is no reflected sound for the microphone to hear. That's not exactly real world conditions that represent a typical end user. In addition, for each added meter of distance from the initial measurement point the audio level typically drops by 3 decibels. Looking at this another way, picture yourself listening to 96 decibels with one watt of amplifier power while sitting in front of a speaker at a distance of 1 meter. Moving your seat away from the speaker to 4 meters distance without increasing the amplifier output you will now be hearing an 87 decibel sound level. At this 4 meter distance you will need to increase the amplifier output to 8 watts to achieve the same volume level at your ears as was present when you were seated only 1 meter in front of the speaker. Move back 1 additional meter to 5 meters distance from the speaker and the amplifier power requirement will double to 16 watts for a 96 decibel sound pressure level at your ears. Even though a highly efficient speaker that produces 96dB with 1 watt at 1 meter is selected, mating it with an amplifier of 25 watts output can be a detriment or not depending on the distance you place your seat from the speakers and at what sound pressure level you commonly enjoy. Remember this, there needs to be sufficient power reserves (headroom) on tap to reproduce the dynamic differences above average level. If it takes 2 watts to sustain your desired average listening level at your selected seating location, you will still need something on the order of 30+ watts available to handle the dynamic range that is present in many recordings.
Changing the speaker efficiency to 86 decibels at 1 meter with 1 watt the perimeters differ dramatically. If you wish to listen at an average level of 95dB at a distance of 4 meters with this speaker, you will need 64 watts of output power not including reserve powerfor dynamics. To faithfully reproduce a 12 dB peak above 95dB average level with this speaker you will need 1024 watts, something a MC1.2KW amplifier can deliver in stride, as can a MC601 on momentary peaks. Both of these amplifier's power ratings are considered by many to be exorbitant but in fact they are necessary with this particular arrangement.
Both of these scenarios are examples of how speaker sensitivity, listening distance, and amplifier power ratings correlate into delivering satisfying listening experiences. It is clear that having additional amplifier power is an asset to reproducing undistorted, unclipped music, thereby protecting our speakers from the damage caused by inadequate power. One needs to consider speaker sensitivity, listening distance from the speakers, typical average music levels required and necessary headroom before deciding on amplifier output power.
The original 16 ohm Altec A7-8 Voice of the Theater speaker had a sensitivity of 101dB at 3 feet with 1 watt. This is the kind of sensitivity one needs to look for when planning to use low output amplifiers. It is all about the proper mating of amplifier power to speaker sensitivity and the sound pressure levels you wish to achieve at your listening position. These things must be considered to take full advantage of any particular sound system.
I hope it helps you understand the relationship of input versus output power and why high powered amplifiers may be necessary, particularly as it applies to your speaker's sensitivity and your common listening levels.
Bill Ferris
Lunatic Member
Dan...have 90 dB speakers in my secondary system powered by 50 wpc and listen at a distance of 13'.
One morning I was playing a CD The Mikado by Gilbert & Sullivan which contains a lot of thunderous orchestral passages which I enjoying playing LOUD and the meters never registered full output (meter reading of +3 dB is 50 watt on an MC2505) on the loudest of orchestral "crashes" which include cymbals, tympani, an array of double basses and chorus. The nearest house to mine is 75' away and it was still loud enough that the police were summoned.
I've had these same 90 dB speakers since 1989 and were used with a 40 wpc receiver up until 10 years ago. They have also been played extremely loudly many times over those years and never experienced driver failure or overload in all that time.
Also don't forget two channels and two speakers means +3 dB above the sensitivity rating for one speaker. So pair of 90 dB speakers at 1/w/m would produce 93 dB SPL at 1w/m.
That's a old post by a friend of mine on another site that writes and speaks better than me. I have it saved, I copy/ past it all the time because this question is always asked. I feel his post is so dead on and easy to understand for someone new thats it's always worth pasting in threads like this.Well put, Dan.
And thank you for going to the effort to convey here, Sir.
damacman
Resident Psycho
Although it fails to address the point I raised as it pertains to having more power than one needs, @Poultrygeist got it - lives it.
Audio, as a hobby, is full of wives tales, mis truths, half truths, slick ad copy, and conjecture. At what point do we stop parroting the same ol' line and ask ourselves - can science itself support what I believe to be true?
The idea that many enthusiasts embrace that having 1.2kw on tap (say via bridged MC2600s - ironic, I know ... ) where 1.2wpc is all that's required to meet the demands as outlined above could in some way make the presentation more engaging, dynamic, or lifelike is simply untrue. However, sitting in ones easy chair looking at 1.5hp/ch of power available and realizing the amps are loafing along is much the same to our psyche as watching two dozen tubes glowing in the dark, watching 10.5" reels spinning at 15ips, or having the grilles off of your speakers - this simply adds to the overall moment. But, let us not allow this euphoria to drive us to a conclusion at which we cannot prove to be true with the laws of physics.
Dan - not pickin' on you ... you know I love ya!
Poultrygeist
Lunatic Member
Many folks who appreciate low wattage amps are SET users. It comes with the territory and I've yet to hear another amp that can resolve detail at low levels like the flea watt single ended triodes.
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Bill Ferris
Lunatic Member
You`re a good man, especially giving the proper credit to the author, as you did, Sir.
Well there sure is NEVER any VANITY involved with big boy toys.......and the inverse.....
At SydAudCom training for pro sound contractors, we were taught to work the system out backwards.
How much dynamic range does the source have, what volume is expected at the numerous seating locations, how much residual noise is present, etc. etc.
Of coarse intelligibility was always paramount because passing AlCons were always part of the specifacations.
It is kind of like how much horsepower do you need to get a ticket......or in this case cause hearing damage.
At SydAudCom training for pro sound contractors, we were taught to work the system out backwards.
How much dynamic range does the source have, what volume is expected at the numerous seating locations, how much residual noise is present, etc. etc.
Of coarse intelligibility was always paramount because passing AlCons were always part of the specifacations.
It is kind of like how much horsepower do you need to get a ticket......or in this case cause hearing damage.
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Poultrygeist
Lunatic Member
And less can be more.
Don't have enough experience to provide a lot of wisdom, but can provide a personal account. I had an 85 watt per chan Yamaha amp driving 8 ohm Dynamo A25 speakers, which recommend 30 watts per chan minimum. I changed in a 30 per chan Onkyo and found it seemed to be straining and distorting running at the same level as the Yamaha.
I knew going in the Onkyo might not have enough power to please me, but as it had pre-outs I knew I could add a power amp if needed and run it as a preamp, as it has a lot of analog and digital inputs I need.
So, found an MC2120 at a great deal and its 120 watts per made a ton of difference. The punch and speed handling sudden transitions in the music, as well as great authority at low listening levels was back and then some.
Since we're doing analogies, I'd say a good one would be the difference between a small weight lifter and a larger lifter in a higher class. The little guy can push up 300 pounds but shakes, strains, yells and makes all kinds of ugly faces doing it. The big man lifts 300 pounds with ease, grace, silently, with a smile.
I knew going in the Onkyo might not have enough power to please me, but as it had pre-outs I knew I could add a power amp if needed and run it as a preamp, as it has a lot of analog and digital inputs I need.
So, found an MC2120 at a great deal and its 120 watts per made a ton of difference. The punch and speed handling sudden transitions in the music, as well as great authority at low listening levels was back and then some.
Since we're doing analogies, I'd say a good one would be the difference between a small weight lifter and a larger lifter in a higher class. The little guy can push up 300 pounds but shakes, strains, yells and makes all kinds of ugly faces doing it. The big man lifts 300 pounds with ease, grace, silently, with a smile.
... can the analogy of an exotic car idling around town with the A/C on and carboning up, running poorly, and a little Camry around town happily doing the same duty also be applicable?
Ever tried holding down and working the clutch in a Countach in the evening traffic-jam commute every evening? Makes for many leg-cramps.
Can you argue both sides of anything with enough abstract comparisons?
Ever tried holding down and working the clutch in a Countach in the evening traffic-jam commute every evening? Makes for many leg-cramps.
Can you argue both sides of anything with enough abstract comparisons?
Holy crap! Is my MC2120 going to carbon up if I don't keep it cranked?
Either you were at extremely high levels OR you are mostly comparing different quality and design in the amps mentioned.
Take 3 basically identical amps from the same designer and compare 30-85-120 watts and there will probably not be any noticeable difference at normal home listening levels.
I couldn't live the way I want to with 95 dB speaks and 10 watts of power.
Small power proponents continue to enjoy what they like and that is fine.
We're not changing so why bother trying?
I have small watt systems and enjoy them as well btw. Just listened to my Tamp connected to Pioneer S-510's last night by the bonfire. Sounded great and got some compliments about that system.
Small power proponents continue to enjoy what they like and that is fine.
We're not changing so why bother trying?
I have small watt systems and enjoy them as well btw. Just listened to my Tamp connected to Pioneer S-510's last night by the bonfire. Sounded great and got some compliments about that system.
I would have to disagree wholeheartedly on this.
Bill Ferris
Lunatic Member
My expression, and one of my motto`s that has never failed me through my adult life, is simply: Better to have more than you think you need, than need more than you have, and feel you need, or find out you need more for whatever task !!
That`s all I have to say about power, any type of power !!
Large amounts of reserve power can be beneficial or destructive, if misused/abused !!
That`s all I have to say about power, any type of power !!
Large amounts of reserve power can be beneficial or destructive, if misused/abused !!