Since the 1/4 inputs on all the current products are mono, can someone confirm that I should have no problem running this cable to connect my laptop to a single channel of a L1, F1, or T4s mixer. This way, I don't have to use takeup two inputs. It has a stereo on the 1/8 end (laptop) and 1/4 Mono on the other side that plugs into the Bose input.
Hello jaswrx,
The cable you refer to will work as far as the Bose equipment goes, however -- it is not a proper method to convert stereo to mono. It is hard on your laptop's output stage and may cause it to overheat and permanently damage it. The 1/8" TRS connector is wired to simply short the L and R signals together.
There are several devices designed to do what you want. They properly convert a stereo signal from a "consumer-level" device (laptop, tablet, phone or MP3 player) to a "pro-level" balanced mono signal suitable for any of the devices you mentioned.
I'm sure there are other manufacturers as well. You can find them on Amazon or a lot of music equipment websites. These devices provide the proper circuitry to sum the two separate stereo left and right unbalanced signals to one mono signal. (The LTI-1 and PC-DI can provide either one or two mono signals or individual left and right signals.)
As far as the T4S goes, I would highly recommend connecting via USB instead of an analog cable. You can route the left and right signals directly to main or channels 3 and/or 4 (to take advantage of the ToneMatch presets and individual volume control.) You can route both the left and right USB signals to one channel (either 3 or 4) to sum them to mono. (I know you're looking to use only one channel on your T4S, but for others reading along -- if you want to maintain true stereo output you can route the USB left signal to channel 3, panning it left, and the USB right signal to channel 4, panning it right.)
Does that help?
Thanks for confirming and for all the good info. I probably have gotten lucky that I have not messed yo my mac.
I assume those single adapters are no better.
Also, I know that all the Bose product's 1/4 is mono, but how often do other manufacturers have a stereo 1/4 input. I would assume only on an older home or prosumer stuff or are there plenty of popular professional devices with 1/4 stereo?
Could one use a stereo cable like this, and just set the computer or mp3 player that has the 1/8 connection to Mono or is this a no-go, b/c the 1/4" connection is still stereo going into the L1 and or T4s?
Hello again jaswrx,
I can't remember seeing any pro devices where the 1/4" inputs are stereo -- not to say they don't exist, but they're probably pretty rare. One the other hand, 1/8" inputs are very often use TRS connections wired for stereo (the Sennheiser bodypack being a noted exception.) 1/4" outputs are a whole different story -- lets of headphones use 1/4" TRS wired for stereo, and newer ones use 1/8" TRS wired for stereo. Then throw in the use of 1/4" TS connectors, XLR's, RCA's, splitter cables and everything else and you have a real connector salad!
I came across a handy web page that is a condensed version of balanced vs. unbalanced at this link from Datapro: DataPro's Guide to Unbalanced vs Balanced Audio It also lists the common usages of all the connectors. Add to this the fact that TRS connectors can be used for either balanced or stereo, and confusion can abound.
That's why manuals or diagrams explaining the exact specs of every jack or plug are very important when connecting one piece of equipment to another.
Thanks for the info.
So I just want to confirm that the little adapter posted above which converts 1/8 stereo to 1/4 Mono isn't really any different than the cable I originally posted as it could still damage my equipment.
Hello again jaswrx,
Yes, the adapter is the same as the cable: Shorts the L and R signals together.
Are you able to confirm if I use a stereo cable (1/8 to 1/4) and set my device's settings (laptop, phone) to MONO that it still won't work bc the cable is wired for stereo on both ends, although it would technically be dual mono with the setting engaged) but still going into a mono input (L1, F1, T4s)
Hello again jaswrx,
1/8" TRS to 1/4" TRS from a device set to MONO to an L1, F1, or T4S probably still won't work. Even though the sending device is set to MONO, it still sends that mono signal to both the Tip and Ring connectors on the jack. The receiving device sees activity on the Tip and Ring, thinks it's a balanced connection, and flips the Ring signal's phase causing the two signals to cancel each other.
This does raise a question that I don't know the answer to: I don't know how your laptop behaves using the 1/8" TRS to 1/4" TS cable from your original post when it's set to MONO. I don't know if having the Tip and Ring shorted is still bad for your laptop if both signals are identical. I'm leaning towards "still bad" as the L and R signals are still being amplified separately (even though they're now the same signal) and shorted together.
Really appreciate your detailed response.
Just on the conversation as the question has arisen in my recent work. It is unfortunate that there is a bad practice of directly connecting two audio sources (L and R of a stereo output in this case). I know of many who have done it with, I must admit, no negative consequence. That is probably because there is usually some sort of protection on the audio output drivers.
The cheapest way to do this correctly is to use a 1/8th stereo to dual mono 1/4 male jacks that can be plugged into the stereo input available on most mixers. Set the sending device output to mono and you are good to go. Otherwise, the devices referenced like fish-54 are the next step up. If you are ok dabbling with a soldering iron, a simpe 3-resistor circuit also works. See
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