Sound pressure, is that the same?

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One ten watts, non distorted amplifier, reproducing a clean 100 hertz sine wave, into a 10 inches diameter speaker mounted in a very big panel (no phase cancellation). the cone movement will be 10 milimeters each half cicle..... 20 milimeters compliance.

Now, a hundred watts, non distorted amplifier, reproducing a clean 100 hertz sine wave into a 10 inches diameter speaker mounted in a very big panel (no phase cancellation). the cone movement will be 10 milimeters each half cicle... 20 milimeters compliance.

This way, speaker factory made new coil, better heat dissipation, more magnetic power and the same chassis with a bigger magnet on it.... suspension the same, also paper cone the same.

Same distance to metering..... can i suppose that i will have the same audio result.... same volume in music?.... in others words, 1 watt audio in a 1 watt full movement speaker will be same as 1000 watts audio in a 1000 watts full movement speaker?

Speaker can have more compliance...... but this have a limit, and this makes sinusoidal into square wave audio when over excited.

So, a bigger compliance speaker with 1 watt can be better than a 100 watt speaker that have lower compliance?

Can i understand that power do not matter..... and everyone making big amplifiers to have more power?.... maybe it will effective only if someone uses more speakers to have more "piston" area pulling air molecules.

Can i understand no need of power?.... that i need hi compliance speaker adequated to the amplifier characteristics to have the best we can have (related sound pressure, volume, decibels) in sound reproduction?

This is real a "stupid" question.... but maybe not so stupid.

Please, let me know what you think.

Carlos
 
Hi,
I guess it's the 'sensitivity' of a speaker you're talking about? I suppose that is the result of variations in compliance and cone construction and materials etc.
So 1watt played through 82dB/W/m speakers will produce the same SPL as 2watts through 89dB/W/m or 4watts through 86dB/W/m. I think that's how it goes anyway, as a 3dB represents a halving/doubling of power.
I think that was what you were getting at
Steve
 
I think you get it, bagstevo82

My English is unclear, i know that...but you get it.

I am asking the people that, do not agree, to explain me some.

And i am trying to say that; if you have a very good an clean 10 watts amplifier, and some speakers very soft suspension.... the one you can move with your breath on it.... you will have a very good air compression.... good sound.... efficient system... adequate power from amplifier and speaker capacity do dissipate the energy, and transform a big amount of energy into mechanical movement to compress air particules, and also rarify, to produce what we capture, and understand, as "sound"

The opposite idea, is when we have a 100 watts amplifier, clean audio and a very hard to move speaker suspension....this way, you will have to spent 100 watts to move this speaker, making the same amount of air pressure than the first one!.... so.... spending power to nothing.

Of course i believe in high compliance units that needs hi power to move it.... but also believe in high compliance units that needs not hi power to move it too.

As i am not sure.... i am asking people....i have my own ideas and i want to check them, or modified them depending people's input.

Thank your kindness to answer my question...you get it!...my idea!

Carlos
 
Hi,
I guess it depends on what kind of sound you're trying to achieve, for example i doubt you'll find many home theater subwoofers running on a single ended 2a3 amp. The system just has to be matched, if you have 100watts available you dont need efficient speakers, if you only have a few, then you do. Each can sound as good as the other potentially I guess, apart from lower power amps being able to use simpler nicer sounding topologies
Steve
 
I think you are on the right track, but have the physics of loudspeakers slightly wrong.

The mechanical parameter that determines the cone excursion in the main frequency range is the moving mass, not the compliance. A high mass will lead to small excursions, a small mass to the opposite. This mass, in combination with the driving force and its frequency will determine the excursion.

But you are right in that the cone excursion, or rather its acceleration determines the sound pressure level. It does not matter if it is accomplished by a heavy cone and a strong driving force, or by a light cone and a weak force. At least that is the basics.
 
Indeed Svante,

And to add to that the bare cone is not matched very well to the acoustic impedance of the air it has to move. So it will always be an inefficient system unless you use an impedance transformer like a good horn or use a cone as light as air ;)

Cheers
 
It is not only the stiffness of the suspension, which brings down
the efficiency of some modern speakers.

The goal is to work with small cabinets.
They offer only small air volume inside. The smaller this
volume is, this air will behave.
In a closed box this acts like an additional spring which is directly paralleled to the suspension of the speaker.
f you gave a speaker with very soft suspension and low moving (that's the next point...), the resonance frequency of this system will become quite high.
The stiffness of the resulting suspension and the moving mass will determine the resonance frequency system.
In vented boxes it is more complicated (two coupled mass/spring systems), but also here you will need a high moving mass in order to work with small cabinets.

The stiffenss of the speakers suspension is reflected in the Vas value of the speaker. Soft suspensions give large Vas. Vas is simply the volume of air which would give the same suspension....

Back to the fundamentals.
If you increase the moving mass, you only get one advantage (lower resonance frequency), but immediately two drawbacks:
-damping gets poor
-efficiency drops

Both can be compensated by designing a very strong magnet and
coil (==> High BL product).
Typically they are designed so that you get again a good damping behaviour. Unfortunately the efficiency drops by the square of the moving mass! So still with a strong motor the efficiency is getting poor.

If we now consider that the resonance frequency does only move with a root function....

It is no fun to get low frequencies and high sound pressure from a small box.....
But with modern speaker designs and power amps you can get amazing results.

Cheers
Markus
 
bagastevo82,Magura,Svant,Pjorl,Chocoholic

Thank you all, the kindness of answer my questions. You put more strengh in some ideas, and also gave me new ways to understand the Whole problem. Not so simple i was thinking off.

I could understand that (I do not read Nelson Pass article yet) are there more complications that needs my reflection... i already put weigth on speaker diafragms, and already burned some holes in centering "spider", also sand papper to make units more easy to move..also i put more magnets, the ones you you can find to increase speaker's magnetic properties (just glue it over the first one certain position).. and also tryed to tune enclosures with PCV tubes (ports, ducts) using sinusoidal generators, amplifier and just hearing the best 35 hertz sound reproduction....lowering ressonance i suppose.

Also discover that box cannot make sound, may be strong and heavy.... 2 inches thickness, and columns from side to side, rounded ones and not so big in diameter...glued boxes and screwed each 4 centimeters with long screws, and also heavy pieces of dampening material alike cotton and PVC glue inside panels... this way, results, are normally reasonable.

Problem is when Misses Eliza, living one floor up related mine, starts to play drum and bass with their giant amplifiers and almost 7 foot high speaker enclosures!, with almost 4 units 15 inches diameter!.... that's i was thinking Eliza where using.... deep bass shackes deeply some objects in my appartment.... till the day i go there and asked Eliza to see the "monster" equipment.

What a shame, but she will never knows the size i imagined, was a small Sony Portable, 8 clean watts RMS each channel, plastic speakers, a cube shape with one 2 inches long thrown driver and a very long plastic tube, going deeply till almost half inches from the internal limit (bottom).

To my protection i said to myself "this is ressonance"... unknown reinforcement....hummmm..... wave length......hummmmm!....bad construction.....hummmm!.....weak construction..... a phenomen... a strange result of material conspiration against my incredible 240 RMS clean power generator (my amp) and my 15 inches long thrown woofers.

I prefered to say thanks and scape as fast as i could from the next shame...I had no time enougth, she turn it on....not appartment ressonance!!, not wave length!, not construction!...just a wonderfull deep bass came from those ligth plastic damn boxes..... if you put your hand in front of duct will feel strong breath of air... and no noises of plastic vibrating.

That sittuation made me re- evaluate my ideas of power and size.

This way, your inputs are all them making sense to me, and together will make me change a lot of things here in my audio system.... and this is fun!

Thank you all, Chocoholic always welcome and others, please take your places to have a virtual coffee with me too.

Chocoholic.... i am thinking in apffel struddell.....das is gut!

Carlos
 
Hehe, funny story :)
Drum n bass, tut tut, at least give that little amp something a bit more challenging to play with!
I expect your system sounds a whole lot cleaner and defined though!! Though if youre speakers have 15" drivers on the bottom end, im imagining them to be some pretty huge 4ish+ way speakers that may need more than 240W to drive them well...
Steve
 
Really bagstevo82, i use a very crazy

I use a very crazy audio system.... 2 channels i assemble using a Sony TA-F30 schematics, an old amplifier, if you look it deeply, you will see P3A there, and many others too, because thopology is almost the same in seventies... those are for bass with 47 plus 47 volts from a giant transformer, and around 30000 uF filter condensers. Mine modified unit goes to not more than 70W RMS-8 ohms, clean audio, each channel.

The input has a passive filter...only bass goes to those channells and speakers is under my Bed.... i will find bed scratch to put it here...i like deep bass frequencies vibrations... alike 15 hertz or something you do not listen, only feel. I am fat and heavy, also the bed is heavy too, and a lot of speakers in home made enclosures and also brand factories, are pointing up to shake my body... the hole bed had 1/2 inches "feet", so, sound passes under bed to room. Standard room apartment sized here... 4 to 5 meters maximum, and floor is covered with white shinny ceramics (BAD!). then i put small carpets surrounding the bed (My surround sistem...hahaha).

In front and up two small, very small, around 4 inches square MDF enclosure with Japanese screaming speakers... these ones you find in small home systems, and those are connected to a separated amplifier, two channels using TDA7265 (8 volts clean audio... more than 18 volts awfull sound).

A Brazilian small audio system Philco (Yes, the american one, old radios and tv sets, the name still alive here!), internal boards chinese, those "cheng kung chei fung " strange factories without adress knowed origin place, inside TDA7265 chips with agc, impossible to distort... very interesting AGC (i want a schematic this way... do not makes audio quality interference, but volume do not answer when reach small distortion levels.. you can turn it up!). This audio system give some voice under bed to broadcasting radio listening of voices... another TDA7264 (almost the same TDA7265) is used in another stereo amplifier, home made too, and this one only to treble... two small triangle boxes with a hi frequency driver (Pionner) is used. So i have 6 volumes controls, 6 channells and the main amplifier using 16 ohms resistor (non inductive) in parallell to their 8 ohms speakers, and audio is taken from the normal system's speaker output. Volume in adjusted in low levels when distortion is 0.3% maximum.

A lot of other amplifiers and Systems i have in the house..JVC, Sony and Sansui ... all them using STK4142II chips inside.... reasonable audio...but cannot hear them long time...put me nervous... something disturbs me... do not know what!

I prefer my bed system, because i can adjust separatelly, and speakers do not be "confused" with others frequencies ordering alike "Goes down!... when main interested frequency order goes front!" also amplifiers are not too much beeing confused (all them passive filters in the input)

But the Sony portable, model 757 is better when listening close and distant... that's the ashamed reality... i tried to discuss with myself and i loose this discussion... also i win it !(crazy?...of course...all of us!)

A dear friend, a very respectable Engineer gave me this input.... and this was so easy to understand that was a very good cooperation... he said:


"Sound will be the same, however it's difficult to get very good and linear speakers
with a sensitivities 100 dB/1W - specially good woofers are hard to get.
Normally only PA speakers are rated with this sensitivity, however these kind of
speakers are normally not suited for HifI, as distortion and reflection from these
are to high for near field listening."
 

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Hmmmm, there's plenty of horn loaded speaker systems about that are well over 100dB, though the horns have to be huge to extend to low frequencies well...
Check the concrete horns!!
and so quite often end up being used with a seperate sub to fill in the 'missing' bass. I'm surprised you were so impressed with that lil sony's bass though, though i guess the clarity and cleanness of sound could have been better. I'm not too much of a fan of mixed and matched speakers and amps all over the place, although multichannel sacd and the like may change my mind on that one.
I'm only 21 so I haven't been exposed to much in the way of real high end stuff (apart from at shows, heard the Audio Note Gakuoh's a few months back :D), but I have a diy 50wpc pp KT88 tube amp running one pair of 91dB floorstanders, which eeeeeeeeeasily blows away any mainstream 'midi' system I've heard. My housemate has well over a kilowatt of home theater stuff in his room (all rotel amps so you can trust the ratings), and I still prefer my setup, so I guess a lot of it is down to taste as well. He's also in the process of making the switch over to lower power single ended triode amps, and making some new more sensitive speakers.
by the way, heres some mainstream speakers well over 100dB efficiency, haven't heard them but they seem to have a pretty good reputation...(no afiliations etc)
http://www.livingvoice.co.uk/airscout.htm
I know theyre nearly 25k, but similar kind of things are still perfectly achievable DIY :D
Steve
 
That's quality, reality.

The sound with real quality passes emotion... when fast rithm put you to dance, when hearing the music you like, you cry...if not!.... its a noise machine....sometimes powerfull, sometimes not, sometimes pretty, sometimes ugly...but, if do not make you "feel".
I think is something that has no identification....like Uerintêingsharenhouser....no meaning, no language!

If you valve sound, passes feelings, and you feel clearly in you mind and in your body...no matter how many Interharmonic subdistortion from a divided rate in fifth instance of farenhouser it will measure.... this is a good sound!

Carlos
 
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