Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!mnetor!seismo!uwvax!uwmacc!uwmcsd1!shop From: shop@uwmcsd1.UUCP (Thomas Krueger) Newsgroups: net.audio,net.analog Subject: Re: Amp designs (Re: current-dumping amplifiers) Message-ID: <1263@uwmcsd1.UUCP> Date: Fri, 22-Aug-86 08:29:11 EDT Article-I.D.: uwmcsd1.1263 Posted: Fri Aug 22 08:29:11 1986 Date-Received: Fri, 22-Aug-86 21:13:46 EDT References: <7773@watlion.UUCP> <3376@jhunix.UUCP> <580@mhuxm.UUCP> <1257@uwmcsd1.UUCP> <581@mhuxm.UUCP> Organization: Computing Services Electronics Shop, UW Milwaukee Lines: 34 Xref: mnetor net.audio:2409 net.analog:833 > > > what is a "current-dumping" amplifier? > > > > Assume you have a 100W (rms) amplifier. If it is 100V at 1A, this is not a > > current dumper. If it is 10V at 10A this amp would be a current dumper, > > useful for driving speakers with very low impedances. (An example is the > > Acoustats with the older matching transformers). > > > Am I correct, then, in concluding that the label "current-dumping" has > nothing to do with the design of the amplifier (since merely putting > a transformer on the output would change the effective output impedance > from 100 ohms to 1 ohm, to use the above example)? Partially... in a solid-state amplifier, transformers are avoided because of the phase shifts and high frequency ringing involved are difficult to compensate for. Therefore, current dumping is not only a function of the output impedance but also of the power supply current capacity. If the power supply is capable of putting 2A into the load, no matter what, the voltage swing on the output would clip as drive to the output stage increased (along with the output stage melting down). If the amp is designed with high current output design with a low ouptut impedance (Accoustat amps come to mind) with a power supply stiff enough (like a lot of supply capacitance and a large power transformer) the amp will be able to 'dump' current without self destructing. As an aside, anyone ever think of desgning large complimentary solid state amplifiers with no power transformer for 120VAC? - Tom -- Thomas Krueger ...ihnp4!uwmcsd1!shop or University of Wisconsin Milwaukee shop@csd1.milw.wisc.edu Computing Services Electronics Shop 3200 N. Cramer St. (414) 963-5172 Milwaukee Wi 53211