How Do Gramophones Amplify Sound with No External Power?

[1832vin]

from what i see, only the vinyl disc is giving energy to the Gramophone; so how does it has a gain in amplitude?
does the shape has anything to do with it, because i notice the same thing with shells

 

[jtbell]

how does it has a gain in amplitude?

That's what the electronics attached to the turntable are for: the phono preamplifier and the power amplifier in particular. The signal that comes out of the phono cartridge itself (stylus and magnetic coil) is very weak.

 

[voko]

The original Gramophone, as per US patent 564586, used copper disks for reproduction. The stylus was mechanically connected to a diaphragm, that would vibrate and thus emit sound. The energy was stored in the spring, that rotated the disk and forced the stylus to undulate. The spring had to be wound manually.

 

[256bits]

If you are inquiring about the early sound reproduction machines, such as the one featured in the famous picture of a dog looking into the horn of a phonpgraph, where there is no electrical amplification, then what is being used to amplify the acoustics is horn technology. You might be familiar with megaphones used by cheerleaders and those long horn type tubes used at soccor games - I forget the name of those things, and the bullhorn used at public address systems. Even the high frequency speaker or tweeter uses horn technology ( as does the woofer but there the absence of a noticible horn is the main feature )
The horn works by acoustic impedance matching. The sound reproduced at the narrow end is limited to a small area which gives a high impedance ( ie higher pressure ) for the reproduction. And as the sound moves through the horn it spreads out, and the wave pressure drops. If you remove the horn assembly and just try to listen to the needle scratching the surface, you will get an idea of why impedance matching is important.