Previously High on Technology has written about USB-C cables and the various permutations of the connectors, conductors and wires. Now we’re going to look at a USB cable tester capable of analyzing what is going on inside your cable. This product integrates the basic function testing of data cables, internal cable construction testing, internal resistance testing, and Type-C eMarker reading. How many conductors are wired to the plethora of connection-contacts? Power handling, data handling and more can all be tested but it requires more than a DIY battery and LED combination. There are at least two Treedix models I found, in this review we’ll be looking at the more expensive model which has a tiny CPU for doing the heavy lifting. Ready for some surprises?
HELPFUL USB-C CABLE INFORMATION
Cables for Thunderbolt-1, 2 and similar looking Mini-DisplayPort are not supported or testable with this tool.
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If you’ve ever grabbed a USB-C cable - patched something in with it, only to discover it does not work - then you’ll understand why having one of these little test boxes in your studio arsenal is a very good thing. As we previously covered here, USB-C cables can look very similar on the outside but have very different wiring combinations on the inside. With the exception of Thunderbolt USB-C cables there is no consistent marking on the outside to help the user discern what exactly you’re using or getting. Thunderbolt cables have little lightning bolts printed on them for identification (and to help justify their higher prices).
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| THUNDERBOLT CABLE, Notice the little lighting bolt on the plug, Click to enlarge |
HARDWARE PHYSICAL DESCRIPTION
The Treedix USB C Cable Tester III is tiny and very light weight (it weighs less than most USB cables and can be pulled off the bench easily by the weight of the wire if you’re not careful). It’s powered by a single internal AAA battery (which it comes with but you need to remove the plastic wrap for it to work) or you can power the tester from an external 5V USB power supply. I’ve been using ours on battery. The manual says it will operate for about 2-hours on a fresh battery.
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Dimensions - the tester itself is a little less than three-inches wide, two-inches high and half an inch thick. On the front is the display screen which is a 2.4-inch TFT color screen with LED backlight.
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| Port-A connections |
It comes in a tiny box and has a surprisingly helpful printed manual in several languages. You'll find a copy of the full manual at the end of this review.
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| Port-B connections |
HARDWARE DETAILS - connectors, button and switch
- On the right side (PORT A) are two USB connectors, one is Type-C and one is Type-A.
- On the bottom are five more connectors (PORT B) which include Lightening, Mini-B, Type-C, MioroB 3.0 and MicroB 2.0.
- On the left side is the “Function Button”, Power Supply Switch and Type C 5V power supply input in case you want to power it from an external source other than the internal battery.
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| Controls and power inlet, Click to enlarge |
There are four different screens that you can move through to get information about the cable you’re testing. To get from one screen to another you press the single very tiny button on the left side of the tester (controls) - a single press moves you to the next screen - after the eMarker test (the last one of the four) another press takes you back to screen one.
To test a cable you connect one end to one of the two Port-A connectors and the other end to the appropriate Port-B connection across the bottom, turn the tester on and almost instantly you’re looking at screen 1 referred to as Basic Function Test. The presence of a green LED next to each data type indicates the cable under test is capable of delivering this function. For full descriptions of all the functions refer to the photos from the Treedix user manual.
TESTING FUN
If you’ve been in the computer game for more than a month you’ve probably got some USB-C cables and adaptors for dealing with the evolution of desktop computing and cellphones. Now that we have these C-to-C USB/Thunderbolt cables that eliminate gender and polarity, plus they all look the same on the outside (typical USB-C style cable)… Treedix to the rescue - finally I can test a cable and find out what it really can do with power and data.
I worked my way through a pile of odd cables very quickly. Here is what I discovered in my cable box:
- Power only - no good for USB 2 or 3 data. Use them for charging hand warmers.
- USB-2 type data, a slower, older digital stream
- USB-3 deluxe
- Thunderbolt-4 passive
After testing I tagged each cable so I could tell the best application for it when I come looking in the stash. The Thunderbolt-4 cable from OWC is not cheap. It is marked with the appropriate lightning bolts on the connectors but could easily be lost in the sea of cables without a tag.
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I recently bought some more-expensive USB-C cables and as soon as they arrived I ran them on the Treedix tester. I was happy to see the performance of the more expensive power and data cables justified their higher price (they look identical to some cheaper cables that test lower with USB-2 data rate).
ADAPTOR(S)
If you have peripherals and need to go from USB-A to C or similar bridges to cross, you may have bought some inexpensive little adaptors to make your existing cable work. I have several USB adaptors here and many of them dramatically cut performance of the cable I adapted with them. Repeatedly I found that a small “C to A USB adaptor” downgraded a cable from “USB-2 with power delivery capability” to power-only. It costs more to buy cables that don’t need adaptors but it seems that adaptors can introduce errors and problems so it kind of matters how much your time is worth to you trying to sort all this out. The Treedix tester made learning the truth much easier and faster. I threw away about a dozen inexpensive adaptors after testing. 
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| Premium OWC Thunderbolt USB-C cable under test, Click to enlarge |
EPILOGUE
I really like this little tester, it has empowered me to do more with my studio gear and help troubleshoot when something is not working. I’ve been testing a bunch of different audio interfaces lately and they all need a connection to the computer - the last thing I want is problem cables. Good old USB-2 is fast enough to easily handle an 8-channel interface at 96kHz. The new SSL Alpha-8 has eight line input and output channels and can sail along at 192kHz (which technically still would work in USB-2; but it is pushing the boundary). The USB-3 input to my computer is a classic type-A 3.1 hole but the USB output on the Alpha 8 is USB-C. To eliminate adaptors I bought a premium USB C to A cable, before use I tested it on the Treedix and then put it into service and it worked flawlessly. I love when things just work!
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I bought my Treedix from Amazon, the price there floats around from $45 to $55. Buy yours wherever you like to buy computer accessories. The Treedix USB Cable Tester III is a winner, if mine died I’d order a replacement immediately.
Thanks for reading High on Technology, Good Music To You!
©July 2026 by Mark King, it is NOT ok to copy or quote without written permission from the author.
Originally published July 10 2026
TREEDIX USB CABLE TESTER III - User Manual, click on the photos to enlarge them.
