{"id":4976,"date":"2012-05-03T16:49:28","date_gmt":"2012-05-03T20:49:28","guid":{"rendered":"http:\/\/www.engineeringradio.us\/blog\/?p=4976"},"modified":"2023-04-29T08:51:23","modified_gmt":"2023-04-29T12:51:23","slug":"summing-to-mono","status":"publish","type":"post","link":"https:\/\/www.engineeringradio.us\/blog\/2012\/05\/summing-to-mono\/","title":{"rendered":"Summing to Mono"},"content":{"rendered":"\n

It is surprising to me how many times I have seen this done incorrectly in the field. Summing a stereo source, whether it is balanced or unbalanced is not simply twisting a couple of wires together.\u00a0 This will effectively reduce the impedance of the outputs by one-half. With newer, active balanced outputs, this may cause damage to the output amplifiers.<\/p>\n\n\n\n

The parallel resistance formula is thus:<\/p>\n\n\n\n

\"\"<\/a><\/figure>\n\n\n\n

Therefore a 600-ohm stereo output tied together would look like this:<\/p>\n\n\n\n

Rt = 1\/(1\/600+1\/600) or 300 ohms.<\/p>\n\n\n\n

It also creates an impedance mismatch with the next piece of gear, which will affect the common mode noise rejection of the circuit.<\/p>\n\n\n\n

The best way to sum is through a resistive network.  That way stereo separation is maintained, the impedance of the output circuits is maintained and the output amplifier will not current cycle.  That looks like this:<\/p>\n\n\n\n

\"resistive<\/a>
resistive summing network<\/figcaption><\/figure>\n\n\n\n

Pretty easy to fabricate in the field.  It is good to do things the right way, it sounds better on the air too.<\/p>\n","protected":false},"excerpt":{"rendered":"

It is surprising to me how many times I have seen this done incorrectly in the field. Summing a stereo source, whether it is balanced or unbalanced is not simply twisting a couple of wires together.\u00a0 This will effectively reduce the impedance of the outputs by one-half. With newer, active balanced outputs, this may cause … Continue reading Summing to Mono<\/span><\/a><\/p>\n","protected":false},"author":4,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[4],"tags":[306],"class_list":["post-4976","post","type-post","status-publish","format-standard","hentry","category-tech-stuff","tag-audio"],"_links":{"self":[{"href":"https:\/\/www.engineeringradio.us\/blog\/wp-json\/wp\/v2\/posts\/4976","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.engineeringradio.us\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.engineeringradio.us\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.engineeringradio.us\/blog\/wp-json\/wp\/v2\/users\/4"}],"replies":[{"embeddable":true,"href":"https:\/\/www.engineeringradio.us\/blog\/wp-json\/wp\/v2\/comments?post=4976"}],"version-history":[{"count":5,"href":"https:\/\/www.engineeringradio.us\/blog\/wp-json\/wp\/v2\/posts\/4976\/revisions"}],"predecessor-version":[{"id":11607,"href":"https:\/\/www.engineeringradio.us\/blog\/wp-json\/wp\/v2\/posts\/4976\/revisions\/11607"}],"wp:attachment":[{"href":"https:\/\/www.engineeringradio.us\/blog\/wp-json\/wp\/v2\/media?parent=4976"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.engineeringradio.us\/blog\/wp-json\/wp\/v2\/categories?post=4976"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.engineeringradio.us\/blog\/wp-json\/wp\/v2\/tags?post=4976"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}