Direct Boxes (DI’s) with Stereo to Mono Summing


In my article, The Stereo to Mono Summing Cable that No One Makes, I described how to build (or buy) a cable that will take a stereo unbalanced signal and sum it to mono for connection to a PA system (mixer, power amp, etc.). You can connect the output end of such a mono-summing cable directly to a regular line 1/4″ line input. If, however, you need a balanced signal for connection to an XLR mic input on a mixer, you’ll need to use a mono-summing cable in conjunction with a DI box. Since writing that article, there have been several DI boxes that have hit the market that do something similar to what the mono-summing-cable-plus-DI-box combo do, so I thought it might be good to provide a quick overview of some of them. I’ve decided to list these in the order of the selling price from least to greatest. (more…)

Summing Two Mic Signals


One of my most popular articles has been The Mono Summing Cable that No One Makes. I’ve been contacted by more readers regarding that article than probably any other that I’ve written. That article details why it’s a bad idea to use a regular Y-cable or TRS-to-TS cable to sum two (usually stereo left & right) line-level signals to mono by simply shorting the outputs together. It’s ok to use such a cable for SPLITTING a signal, but not for COMBINING or SUMMING two signals. That being said, it can work ok on some devices, but on others it can cause distortion, weird phasing artifacts, and possibly even damage the outputs of your gear. However, combining the outputs of two dynamic microphones is a different story, and in some applications it’s ok to do so with a regular XLR Y-cable, as we will soon see. (more…)

Balanced Line-Level Stereo to Mono Summing Box


One of my most popular blog posts has been The Stereo to Mono Summing Cable that No One Makes. I get contacted pretty much on a weekly basis from someone who wants to buy or build that cable to connect their iPod, phone, laptop, etc. to their PA system. I decided to take the concept a step further and build a balanced, line-level stereo to mono summing box. Just like the mono-summing cable, it appears that there aren’t any readily-available, off-the-shelf products that do exactly what this box does. There are some mic combiners (e.g., Galaxy Audio’s JIB/C) that are made for connecting two microphones to a single input, but those use much lower-value resistors, making them unsuitable for line-level signals (I even contacted Galaxy about the JIB/C, and that’s what they told me). (more…)