OK, so I have an update to the KZ bluetooth cable shielding mod posted here:
https://www.head-fi.org/f/threads/k...essions-thread.698148/page-1282#post-13621972.
It turns out the problem is the length of the antenna. It is too short (24mm total). I have no clue how or why they came up with that length, but that is NOT the correct length for a generic PCB-trace style bluetooth antenna.
The CORRECT length for a quarter-wavelength bluetooth antenna should be 31mm, not 24mm.
If you want to read more about the topic, here is some info that explains the details:
http://bluflux.com/bluetooth-antenna-design-guide-step-1/
If you don't understand any of the nerdy mumbo jumbo, don't sweat - the takeaway is that the KZ antenna is 7mm too short.
Anyways, to correct the problem, all you have to do is extend the stock antenna with a piece of wire.
1. Pop the case apart and remove the board. For details about how to do that, read the shielding mod link I posted above. Next scrape away the coating at the very tip of the antenna until about 1mm of bare copper is exposed (I used an Xacto blade). Don't scrape away too much or too hard or you will scrape the copper trace right off the board.
2. Now you need to solder some sort of small piece of wire to the exposed "pad" you made on the antenna. The best thing to use is the leg from some sort of through hole component (an LED, carbon resistor, etc). I used a small piece of wire, but only because I was lazy to find an unneeded through-hole component. Antennas should really be solid core wire, not stranded wire like I used. But I wasn't even expecting this to work so I really didn't care at the time. When I repeat the mod on my 2nd KZ bluetooth cable, I'll use the leg from a resistor.
3. Anyways, once you have the piece of wire soldered on, trim it to
exactly 7mm longer than the end of the stock antenna. Why not cut it before soldering? It's easier to solder a longer piece of wire and cut it down than to try and solder on a tiny piece of wire. Plus the wire needs to be 7mm longer than the END of the stock antenna, so cutting it after soldering ensures that you aren't counting any material that overlapped the stock wire at the solder joint. In other words, when you look at the photo below, the wire is actually about 8mm long, with 1mm of that length overlapping a section of the stock antenna for soldering purposes. Make sense?
4. Once the wire is soldered, pull the battery away from the back of the board (it's held on by some sticky tape), and wrap the antenna extension around the board. Stick the battery back on the same spot and reassemble the board into the plastic case. The wire is small and thin enough that the case needs no modification whatsoever.
5. Because I've had my case apart a number of times now, the clips don't hold as well as they did the 1st time I put it together. So I just used a few strategically placed drops of super glue to hold the 2 halves of the case together and I was done. Note that you shouldn't need any glue if you've never had the case apart. I only needed a few drops of glue because I've had the case apart numerous times.
What are the results of the mod?
How about DOUBLE THE RANGE with ZERO skipping and interference indoors or outdoors! Yeah for science!
Now that I've seen what's going on, I believe this was the issue all along. There is no need to shield the bluetooth chipset with foil like I showed yesterday. Just do the antenna mod outlined here and you're golden.
Here's a few photos. The 1st photo shows the extension wire soldered onto the end of the stock antenna (after trimming to 7mm). The 2nd photo shows the antenna folded over onto the back side of the board.
You're probably thinking - what a PITA for a $7 bluetooth cable. KZ could have just as easily designed the antenna correctly from the get go. I agree, but at least I can finally use my cables without any annoying skipping, so in that respect it was worth the trouble spent.
The mod itself is technically easy, but you would want to have decent soldering skills, a sharp pointed soldering iron, and good eyesight because the wire is so small. If you've never done anything like this, have someone help you or do it for you. Total time from start to finish was about 20 minutes.
Enjoy!