SPRODIO Single Stereo to Mono Converter, RCA L/R Audio Adapter Stereo to Mono summing Cable Adapter SC21

Well built and does exactly what it's suppose to do. While this device is extremely simple with just two small resisters inside, it's an important thing to use when mixing outputs to ensure you are not causing undo stress on the source audio device's output amplifiers.

FINALLY, a solution for mono output from stereo mix. Looked everywhere for a way to convert stereo output from a basic DJ mixer into a mono feed to a single PA speaker for a mobile rig. Thought this would be easy, but no one seemed to have a simple answer. Sweetwater was baffled, B&H had nothing. Y-cables with adapter had horrible phase issues. Then this little thing did what no one else could do. Stereo to mono, perfect sound. Problem solved.

It works ok but I don't like the fact that the jack colors are swapped from what they show in the picture. The left side is red and the right side is white. Normally, you'd have the right side red and the left side white like the product images show. I know it doesn't really matter but I would have gone with another brand if I had known.

Yes it attenuates, but note that it attenuates a *lot* more if you put it in backwards. It's symmetric and will "work" if you accidentally hook the stereo input up to the mono output side and the mono output side to the stereo input side, so you might not notice. If you're seeing extreme attenuation, check the wires and labels.

If you’re like me and live in an older house with some vintage tech (in my case, a home intercom/radio system from the 70s), you know how fun it is to impress guests with the fact that it still works. The only downside is being stuck with radio ads… or songs you absolutely hate. Fortunately, my unit has an AUX-in via a single RCA connection, and I didn’t have anything that outputs a true single-channel signal. Adding this inline has been a big improvement—rather than just passing one L/R channel through to the speakers, it properly combines the audio and has noticeably reduced the static/crackle I used to get when playing music from my record player or Alexa. Definitely recommend if you’re trying to clean up a noisy connection on older audio gear.

Like a few other folks, the output of this sounds like one channel clobbers the other or some variation of that. My setup is from my turntable to amp to this then a single studio monitor. My Mono 45s sound great. Stereo sound mid at best. Could be some of these are better than others. I wish I’d tested it earlier. I would not recommend this, and am considering just making the enclosure work to accommodate a second monitor and forget mono all together.

I have had trouble combining two stereo channels to make one mono channel for my woofer. The circuit is simple, but building it myself led to a lot of noise in the channel. This little box does the conversion without introducing any appreciable noise to the output signal. I suggest buying the best cables you can find for connecting to the box. I wasted a lot of time trying to diagnose a problem that was just a poorly made cable.

After an hour of troubleshooting, assuming that my stereo output or my speaker were at fault, I finally did continuity testing on the unit. No continuity on the positive side. In fact, all four RCA jacks were missing the contacts for the positive terminal. You'd think they could at least test the product before boxing it up.