Question

Running a 1/8" stereo mini plug out of the headphone jack on the back of the computer into the Line In on the mixer. I'm using a stereo mini into a stereo quarter inch adapter. When we play back some audio we don't get the full frequency range and in some YouTube videos we get decent background music but the audio is really garbled and distorted. Unintelligible. When I pull the 1/4" plug part way out I get full range and the audio is corrected. We are running into one channel for each of two computers. Any ideas?

Answer 1

If you are  connecting a stereo signal into a mono channel you will get what's called a phase cancelation. Phase cancellation occurs when two signals of the same frequency are out of phase with each other resulting in a net reduction in the overall level of the combined signal. If two identical signals are 100% or 180 degrees out of phase they will completely cancel one another if combined.
Here are a couple of ways to correct this. The optimal choice is to to utilize the Stereo Line In inputs on the mixer (if available) which are usually Left and Right RCA connections. If so, use a 1/8" stereo to RCA cable to connect the computer or other audio device to the mixer. Here's an example of the cable:

https://www.walmart.com/ip/Monster-Cable-MusicConnect-1-8-Mini-jack-to-RCA-Cable-for-iPhone-iPod-Smar/144097133?wmlspartner=wlpa&selectedSellerId=6914&adid=22222222228057717247&wmlspartner=wmtlabs&wl0=&wl1=g&wl2=m&wl3=161636121003&wl4=pla-269356546771&wl5=9025385&wl6=&wl7=&wl8=&wl9=pla&wl10=115059300&wl11=online&wl12=144097133&wl13=&veh=sem.

Otherwise, you'll need to use a 3.5 mm to dual 1/4" cable as shown here:

https://www.google.com/imgres?imgurl=https%3A%2F%2Fwww.goodworlddeals.com%2Fwp-content%2Fuploads%2F2016%2F04%2FNEW-Hosa-CMP159-Stereo-Breakout-3.5-mm-TRS-to-Dual-14-in-TS-10-Feet-BRAND-NEW.jpg&imgrefurl=https%3A%2F%2Fwww.goodworlddeals.com%2Fproduct%2Fnew-hosa-cmp159-stereo-breakout-3-5-mm-trs-to-dual-14-in-ts-10-feet-brand-new%2F&docid=QFoZNFS6XSpR_M&tbnid=QtlhOojAn101fM%3A&vet=10ahUKEwju7NXChPfTAhVjzoMKHX3sCvsQMwhTKAEwAQ..i&w=500&h=250&itg=1&safe=off&client=ms-android-verizon&bih=609&biw=360&q=3.5%20mm%20to%20dual%201%2F4&ved=0ahUKEwju7NXChPfTAhVjzoMKHX3sCvsQMwhTKAEwAQ&iact=mrc&uact=8.
You'll connect each 1/4 " connector into individual line in channels on your mixer then pan the channels opposite each other.  The only setback is that you use up 2 channels instead of just one.

Hope this helps!