Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Posting-Version: version B 2.10.2 9/5/84; site edison.UUCP
Path: utzoo!watmath!clyde!burl!ulysses!gamma!epsilon!zeta!sabre!petrus!bellcore!decvax!ittatc!dcdwest!sdcsvax!sdcc3!sdcc6!ncr-sd!ncrcae!ncsu!uvacs!edison!dca
From: dca@edison.UUCP (David C. Albrecht)
Newsgroups: net.audio
Subject: Re: on crossovers - active vs. passive
Message-ID: <574@edison.UUCP>
Date: Mon, 21-Oct-85 12:02:42 EDT
Article-I.D.: edison.574
Posted: Mon Oct 21 12:02:42 1985
Date-Received: Sat, 26-Oct-85 04:46:17 EDT
References: <1259@tekgvs.UUCP>
Organization: General Electric Company, Charlottesville, VA
Lines: 20

> 	Put a long-duration pulse to the speaker (long duration being
> several times longer than 1 over the resonant frequency). The cone
> moves out, then moves  back. But when it moved out, it probably
> over-shot the "correct" location and oscillated into place, finally
> getting to where it was supposed to be. Thes oscillations generate a
> "back emf" (remember that from your power engineering classes?) that
> tries to drive the amplifier.

I'm kind of interested in this also.  I did see a circuit in a TI
application guide which used a 5534 as driver for a low powered
amplifier < 20 watts directly connected to a speaker.  The unusual
thing about it was the circuit used current feedback from the
speaker by puting a 0.5 ohm resistor in series and feeding back
the voltage to the 5534.  I was curious if anyone had comments
on the use of such feedback in multi-amp speaker designs (i.e.
general usefulness, should it be used only for the bass drive
or is it good across the spectrum, etc.).


David Albrecht