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Old 06-04-2008, 10:02   #16
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Class 'A' Amplifiers

I guess it is worth mentioning that if you have an external amplifier and it is called a 'class A' amplifier there is a good chance that it draws the same on min/max setting, that is how those function.

It is not normal to use calss a on built in car stereo systems but might be worth finding out.


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Old 06-04-2008, 10:10   #17
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This has been one of the more enlightening questions that I've ever asked... Thanks guys!

Alan, if the wave is being sent to the speaker, but the speaker can't utilize it, could one open up a program that shows an MP3's wave pattern, and simply cut out what the speaker, or ear can't hear?

So I have another question... If one wanted to measure the watt output for decibels at one meter, and they had a decibel meter and a clamp on amp meter... (mines not fancy enough to think in RMS) arrive at a figure close to the 1watt/1m and decibel output? (I assume I'd need to use an oscilloscope to get into units divisible by 50 or 60 hertz that my meter thinks in?)

Alan, when the current reverses does it do so with an equal amount of power? (Trying to figure if I'll need to clamp more than one wire with an amp meter... If both wires are simply alternating with the same charge for each and every transition between out and in I can deal with that. I'll claim black magic if theres a vector!)

Steve, Good point on heat, I'll check into that.
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Old 06-04-2008, 13:45   #18
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Wow, lots of questions. I try and pick through them. I better tell my secratery to hold all calls for a while.

Quote:
'Efficiency (1W/1M): 90dB' as Sony has 90 for theirs as well. Is that good
I am surprised you found that. And yes, for domstic product, that is not bad at all. BUT! do they say what frequency. Now here's the next piece of carpet they hide specs under. No speaker, or enclosure is perfect in freq response. Each has a "tone" or "voicing". Some may like the tone, some may not. But a speaker or enclosure that delivers a flat response often sounds 'lifeless". However, that "voicing" is due to frequncies that are louder and softer over the spectrum. So some manufacturers use the "peaks" of the response to gain their figures. "Real" manufacturers will give you a range of figures, or even a "Response Curve". That is a graph that shows the entire spectrum the speaker reproduces and how well it does. Yet another series of traps in that though. The figures they print are often unreadable or are not correct terms and could show you are nice reponse curve, but in reality isn't.
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Old 06-04-2008, 13:57   #19
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6"9 is in my opinion a little 'hard' on the consumption so i like the round ones around 5".
No the shape, size and colour makes no difference at all. Size makes no difference to how low a speaker can operate. Bass is created by moving huge volumes of air. Air is moved in two ways. The square area of the cone and the distance it can travel. The ability of reproducing a low frequency sound we can actually hear, is a result of the motor(the magnet and Voice coil) and the box it is in. Each speaker desing requires a specific volume of airspace behind it to make it work. Bass speakers for concerts used to be the size of Mini's. The speakers I used for concerts were quarter of that size and could put out more sound with one than 8 of those big ones. Micheal Jacksons famous concert in the Desert used only 8 of them. And 7 Diesel electric trains to supply the power by the way. These special sub boxes are also being used in Airports around the world to combat noise from jets taking off. The jet at take off is picked up through a microphone and fed through the speakers out of phase. The result is the sound is canceld out and the people don't hear the jets. Same techneque is used in some cars today to make the inside really quite to road noise. Ooops, I'm off again.
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Old 06-04-2008, 14:04   #20
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'class A' amplifier there is a good chance that it draws the same on min/max setting, that is how those function.
No not quite. Yoyu are correct that the output device draws a current and the current is the same fully on and fully off. But that is the operating current for the device(transistor) itself. The actual current driving the speaker is constantly changing. It's another one of those, incorrect use of terms. To understand it correctly, all Modern Amplifiers are Voltage amplifying devices. Not current. But that is complex and huge and I won't bore you all by going there.
Someone has already answered correctly that power consumption of a head unit is high due to a lot of wasted power used fro display's etc.
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Old 06-04-2008, 14:09   #21
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Alan, if the wave is being sent to the speaker, but the speaker can't utilize it, could one open up a program that shows an MP3's wave pattern, and simply cut out what the speaker, or ear can't hear?
If the player has such a facility, then yes absolutly. Cut the lower range off and the upper range. It will allow you to go louder with less power used.

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Alan, if the wave is being sent to the speaker, but the speaker can't utilize it, could one open up a program that shows an MP3's wave pattern, and simply cut out what the speaker, or ear can't hear?
Yeah pretty much. Place the meter 1m away from the speaker and send a tone to the speaker. But know what watt is what is very difficult and requires a lot of test gear to ensure you have the right power. A current meter will give you a close guess. The main thing is if you are testing a range of speakers, use the same test tone and current for each. It may not be accurate in one respect, but will be over the group.

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Alan, when the current reverses does it do so with an equal amount of power?
Yes and no. If you feed a pure tone in, then yes it is equal. But Music and voice are not equal. Otherwise you wouldn't hear differences, it would all be plain pure tones.
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Old 06-04-2008, 15:14   #22
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How about this??

The power consumed by a stereo is mostly proportional to the "loudness" coming out the speakers. So the louder you want it, the more Battery power used. Low frequencies take the most power, so thumping bass is soaking up your battery power quickly. To be able to hand crank something to produce music, it would be more like, crank for an hr to listen to a few minutes of Audio. There are small hand crank charged Transistor radios available. Personly, I think you would be best to use something like an Ipod and in ear phones. Batteries last awhile and you get good sound.
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Old 06-04-2008, 21:04   #23
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Alan, your my hero. I feel enlightened.

Any particular designs for enclosures one should look for, or build to amplify whatever sound is around? Like putting a 5" midrange speaker at the back of a megaphone, sort of like ye olde hand crank record player?
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Old 07-04-2008, 01:09   #24
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Like putting a 5" midrange speaker at the back of a megaphone,
Well that isn't a silly idea. So not silly, that it is exactly what they did do way back. Because speakers and amplifiers simply were not big enough. My biggest Rig was 100KW. The big amplifiers I use were 2500W each channel. That system comfortably handles around 20,000 people for a Rock concert. My biggest crowd was 65,000, but it was not a rock concert. However, a Friend of mine was one of the engineers at Woodstock. Yep that's the original woodstock. The biggest amplifier they had in those days was just a meesly 80W. The speakers were not much different. So they had to use lots of them. Lots of 80W amps and the speakers were all mounted on Horns. Great enormous exponential plywood Horns. I used to have some in my very early days. The boxes were big enough to stand up in. Damn near big enough to set a bed up in actually. A few companies that have no clue still play with horns today. And you will see them on somen Warfedal home speakers. The problem is, sound is a variance in sound pressure. It comes from the speaker to the ear in a series of waves. Each freq, has a different wave length. Just like an ocean wave. In fact all aspects of the Ocean wave are the same as sound. The louder the sound, the higher the wave. The closer the wave( or more waves in a given distance), the higher the sound freq. A horn is just like a harbour entrance that has a breakwater. The big ocean waves won't get through the narrow gap, but the smaller waves will. Well if you turn that around, the smaller waves can fit out the gap easier than the bigger waves. So being the same in sound, the Horn makes some sounds more prominant and other sound less. So the box gets harsh and nasty. Then there is quarter space loading, half space loading and on and on it goes. It is all important to gain the understanding, but I am speaking from years and years of experiance and I will go right over all your heads, if I haven't already. But I have to say, it was one hell of a ride playing with sound and the physics of it at the level I was at. Believe it or not, although much of the ground work in physics of sound was laid down many many years ago now, the ability to get great sound was beyond the industry for the last 40 years. Even right up untill now. It is only in the last couple of years that we have finaly reached what I would consider the holy grail in sound. That is being able to create a "sound stage" to the listening Audiance that if they were all blindfolded, they shouldn't be able to tell the difference between a CD and the real thing. For me, it was a very special privialge to have been able to work with the top guy's in the world on audio design. Lookign back, it was rather special that some huge manufacturer woudl actually listen to what me and a few other guys in the industry had to say. They would ask questions on designs of the equipment and then a year later, would release some new console that had everything we had suggested on it. That was really something. But the special part for me, was working with beam stearing and phase technology in speakers. Don't get me wrong, there are guy's out there way beyond me in the Brains department. But they woudl get me to field test. Allow me to modify their programmes, listen to my comments, go back to the drawing board and come backout the next season with improvements. The result was, we are seeing speakers today that go louder, cover a wider frequency range, and are much smaller in footprint. Today we are no longer talking about a 50Hz-16Khz Concert range. Some guys are playing with freq's. upto 30Khz. We don't hear them, but apparently we sense them. I was taking my concert low end down to 20Hz. Some are down to 18Hz. Once again, it is a sensation. You don't hear 20Hz, but mate do you feel it.
Ooops, I've done it again. Sorry folks, I really apologise. I am addicted to sound. But a wee story before I finsih. I have a mate that designed my bass bins. He is an amazing man. Anyway, he had to build a Bass box to reproduce the Sonic Boom of the Space shuttle on re-entry. The box he created shifted a two story building six inches off it's foundations. The speaker, if you could call it that, created a frequency of 3Hz at some 170dB. The loudest sound that can be supported by our air is about 180dB. After that the air cavitates and the sound crackles. You may hear that crackle in the sound of the shuttle at lift off. Now here is an amasing fact. A Whale (can't remember which one) can produce a sound underwater of 180dB. That is loud enough for other whales to be able to communicate thousands of miles away.
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Old 07-04-2008, 01:45   #25
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What a legend set of posts Mr Wheels. After all these years of thinking one way to find out I've been conned in my search for more power, well dB's anyway, I feel suddenly a pile more enlightened. Been looking at car/marine audio numbers and there does seem to be a pile of, well nothing substantial really. None seem to have any power consumption numbers of any sort. Makes me wonder how much they do actually suck and I'm suspecting it could be big numbers.

I remember those massive horn type speakers and now I know why. Remember a specific Midnight Oil concert and at the front right by the speakers 'feeling' a lot more than we seemed to be hearing. Something a couple of us commented on afterwards. They were certainly pushing a lot of air around. Hearing took a while to come back, like a few days at least.

It took 7 trains to power a M Jackson concert? I can say I'm not a great fan of his music but I now love his sound crew and the power they sucked up. That's magnificent of the 1st order, a real 'More Power Tim' moment.

So now I'm about to annoy the crap out of Sony and a couple of other local suppliers for some real tech specs inc Response Curve's. Might be interesting to see what they come back with. They will regret your post as yet another enthusiastic amateur let loose on some poor unsuspecting stereo salesman

I remember something not too long ago about how they are teaching deaf people music by 'the feel' rather than the noise. They were glueing a small speaker (I suppose) to their heads and one to the belly and they could feel the vibes. Seemed to work very well for some.

Thanks and feel free to digress, you do it well and it's damn interesting.
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Old 07-04-2008, 01:54   #26
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That is amazing stuff Alan.

A sonic boom maker...

So for giggles and grins, if we took a megaphone and pointed it against a flat surface... and only wanted the sound that bounced off the wall, could we cross our fingers that the distortions happen less often than the clean waves and try to let those be canceled out?

Sort of like cutting out resonance in a car muffler, cut out just the frequencies that are off tone and leave the rest?
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Old 07-04-2008, 13:37   #27
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The problem with Walls and rooms is that they aren't so good at reproducing sound. A big mistake that is still made to day by the "amatures" in sound engineering, is trying to take out the problem reflections/vibrations in a room, by using a thing called a Graphic Eqauliser. Some car Audio have toy ones. They may have 5 bands of EQ filters. The real nmachines in our industry use 36bands and the real techy ones allowed you to tailor what freq and how much of it you wanted to change. Now the problem is, you can not use one of these to "tune" a room as is still often done. I flawed the adio world one day by making one of my typical tongue in cheek statments, that there is only one EQ in the world that can actually tune a room. It is called a D9 and is coloured yellow. I had people all over the world contact me askign were they could get one from. I linked them to a certain company. Anyone want to guess what a Yellow D9 room EQ is??? When they finaly clicked, it turned the world of proffesional sound upside down and the real pro's that know and understand this now, do things very differently.
The Sound Forum(much like this one) didn't take prisoner's. A smart comment like that one I made is expected. Remember, it is our carrers and we don't let go of the experiance easily. Many of the members were competitors. So letting go valuable info results in the competitor getting an edge against you. The big name live sound engineers would click onto things like that real quick. And you didn't mind them doing so. We learn't a lot from each other. But newbies were just mice and we were the cats. I made a lot of friends with sound guys from some of the biggest bands in the world. It was cool to be able to share information backwards and forwards. And for me, especially cool for this little Kiwi farm boy in the backwaters of NZ to be able to have some small minor part in the way an audiance hears a group like Red Hot Chillies for instance. I know there sound guy real well.
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Old 07-04-2008, 13:51   #28
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Perhaps to keep this on track of Sailing. I have 5.1 surround and sub system on the boat for movie's and a nice wee system in the aft cockpit that I love turning up Pink Floyd or Foofighters etc when sailing. Seafox and Marauder got a good tast of Floyd the other day. Learnign to fly is fantastic on the water when in the right conditions.
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Old 07-04-2008, 16:24   #29
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Perhaps to keep this on track of Sailing. I have 5.1 surround and sub system on the boat for movie's and a nice wee system in the aft cockpit that I love turning up Pink Floyd or Foofighters etc when sailing. Seafox and Marauder got a good tast of Floyd the other day. Learnign to fly is fantastic on the water when in the right conditions.
Alan,

Would you be so kind as to discuss a bit more about wattages of your system, the speakers you use and a bit on power management.
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Old 07-04-2008, 16:38   #30
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Can you get amphibious yellow D9's for tuning a sail boat ?

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