Members Mudbass Posted November 13, 2003 Members Share Posted November 13, 2003 http://www.lenardaudio.com/education/14_valve_amps.html Came across this article and found some claims I'd never heard before, in particular... "Solid-state amplifiers behave in 'Voltage Drive'. This acts as a short circuit (zero output impedance, or 100% damping factor) across the speakers, causing excessive damping, which reduces efficiency, limiting responsiveness. Valve amplifiers behave in 'Current Drive'. This represents an open circuit across the speaker without over damping, allowing maximum response and efficiency". ...and "Solid-state amplifiers are inherently nonlinear. They have a very large 'open loop gain' approx 20,000. The amplifier output is (feedback) to the comparator input to reduce the gain to approx 50. Therefore 99.9% of this feedback corrects all instability and non-non-linearity of the amplifier, as explained in amplifiers. The speaker also acts as a large microphone. All non-linear movements and vibrations within the speaker cone, (caused by reflected nodes, chaotic resonances etc) of which there are many, are regenerated back into electricity by the voice coil. This re-generated signal from the voice coil is inadvertanetly fed-back to the solid-state amps comparator input, and re-amplified back to the speaker as recycled distortion". Fact or junk science? Link to comment Share on other sites More sharing options...
Members agedhorse Posted November 13, 2003 Members Share Posted November 13, 2003 Yes and no. Solid state amps are a voltage source, with very low source impedance. This means that the voltage that the amplifer's output defines remains constant regardless ofthe load. The current will change to achieve that voltage. Tube amps are similar to solid state amps in that they also require feedback to stabilize. Generally the open loop gain is not as high, but it can be. Their inherent output impedance means the the output voltage will change with load somewhat. Neither SS or tube amplifiers are really more non-linear. They exhibit some different characteristics, but the overall design plays a large role too. Link to comment Share on other sites More sharing options...
Members Daniel Smart Posted November 14, 2003 Members Share Posted November 14, 2003 The speaker also acts as a large microphone. As I remind people every time they plug the wedge into 'line in' on the powered monitor instead of 'speaker out' and wonder where the feedback is coming from -Dan Link to comment Share on other sites More sharing options...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.