Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10 5/3/83 based; site hound.UUCP Path: utzoo!watmath!clyde!burl!ulysses!mhuxr!mhuxt!houxm!hound!rfg From: rfg@hound.UUCP (R.GRANTGES) Newsgroups: net.audio Subject: Re: Speaker Sensitivity Message-ID: <1451@hound.UUCP> Date: Wed, 30-Oct-85 23:37:19 EST Article-I.D.: hound.1451 Posted: Wed Oct 30 23:37:19 1985 Date-Received: Sat, 2-Nov-85 01:48:14 EST References: <480@uvaee.UUCP> <601@bonnie.UUCP> Organization: AT&T Bell Labs, Holmdel NJ Lines: 29 [] Well, one more bit of information. Its not the type of box, so much, folks (horns aside) but the sound pressure level the designer is aiming for. If you're not using a horn and you want loud sound at low frequencies, then you have to move a lot of air. For a given diameter cone, louder means more cone excursion (in and out). Speakers designed for big excursions (so called "long throw") have the problem, "How do you keep a long travel linear?" 1) You have to keep the suspension linear - solutions discussed earlier. 2) you have to keep the voice coil seeing a constant magnetic field throughout its travel. For long travels, the easiest most economical way to do this is to make the voice coil much longer than the magnetic field. That way however it moves the coil still sees the same field. However, it means that only a small part of the field of the voice coil is being used at any time. Hence, a loss of efficiency. If you decide to live with not so big excursions then you can still get your frequency response and efficiency in the small box, only don't play loud. Horns act like transformers and couple the speaker to the room. You can get loud sounds, large air motion, with small speaker excursions, hence no need for long throw design (but watch out for the speaker suspension when you drive the speaker below its cutoff frequency. -- "It's the thought, if any, that counts!" Dick Grantges hound!rfg