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bypassing old intercom system (45ohm + 150ohm resistors)
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<blockquote data-quote="Craig Hauber" data-source="post: 88939" data-attributes="member: 272"><p>Re: bypassing old intercom system (45ohm + 150ohm resistors)</p><p></p><p>One of your 200-ohm speaker/resistor combos works out to about 25W on a 70V line. The 45-ohm speaker by itself is around 110W. </p><p> Figure out a way to series a few of them and put them all on a basic 70V paging amp with no transformers needed.</p><p></p><p>Finding a line transformer for a 45-ohm voicecoil won't be easy as I think 45-ohm speakers were designed for direct connection to 25V amplifiers as normally used in school intercom systems (around 15W when on a 25V line) </p><p></p><p>When we use shielded twisted pair for speaker lines (not very often) I generally ignore the shield</p></blockquote><p></p>
[QUOTE="Craig Hauber, post: 88939, member: 272"] Re: bypassing old intercom system (45ohm + 150ohm resistors) One of your 200-ohm speaker/resistor combos works out to about 25W on a 70V line. The 45-ohm speaker by itself is around 110W. Figure out a way to series a few of them and put them all on a basic 70V paging amp with no transformers needed. Finding a line transformer for a 45-ohm voicecoil won't be easy as I think 45-ohm speakers were designed for direct connection to 25V amplifiers as normally used in school intercom systems (around 15W when on a 25V line) When we use shielded twisted pair for speaker lines (not very often) I generally ignore the shield [/QUOTE]
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