On Thu, Jul 28, 2011 at 05:30:55PM -0700, Robert Greene wrote: > I am not an electronics designer but I think the causes of > current limiting and voltage limiting are in effect different. > Of course the one actually happens when the other happens: > an amp cannot maintain voltage without maintaining current too > (and vice versa). But I think the causes of limiting into high impedance > and low impedance are different. > Current strength(which is what gives out in this informal sense into low > impedances) is attached to big power supply storage and (I think) lots > of output devices paralleled , and voltage(which is what limits when the > speaker impedance is high, again in this informal sense) is attached to > the rail levels or the voltage limits of the output devices.
Correct. Output voltage is limited by the voltage of the power supply and any voltage lost in circuit elements. If you try to go above it the signal will simply be clipped. More sophisticated amps will monitor this and stop you from driving their high power parts into saturation by limiting the input voltage. Current is limited by what the power supply can deliver, and in almost all amps is *actively* limited regardless of that to protect the amp itself, both against excessive current AND excessive internal power dissipation. For the latter, the current limiting is usually made dependent on output voltage: more current is allowed when the momentary output voltage gets higher (and voltage drop over the output devices delivering the current gets lower). This can lead to an amp having problems driving a reactive load. Very high power amps as used in PA do monitor all of this, they are well aware of the impedance they are driving and have data interfaces reporting a variety of performance data to a centralised monitoring and control application. But in all cases, as long as they are working within their normal limits, they are supposed to be voltage sources, with the resulting current being whatever it takes. Ciao, -- FA _______________________________________________ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
