I'm in the process of replacing the GK3 kit I installed in Arkieboy's Hexacaster with a GK5 kit. I'd planned to reuse the 13-pin socket location as it has the same size socket panel so would physically fit back in the same place.
Apart from Boss unhelpfully changing the push-fit header connector sizes so I can't simply plug the old wiring (where appropriate) into the new board, the output lead from the GK5 kit board to the jack socket is stupidly short IMO.
On a Strat you've pretty much got to rout out a cavity for the board in the location where its shown in the photos, which means there's no way with the ferrite bead on as it is, that it will reach the location I'd want it to and I'd pretty much have to drill another hole in the side of the guitar if I used it as-is.
So my question is, if I get another ferrite bead and just do a single pass for each one, would that do the same job as the double pass though a single bead? There's enough length in the cable if I do that.
Cable with ferrite bead removed:
I feel the answer should be yes, but it's not something I'm really up on.
Or would I be better swapping the existing ferrite for one of a higher impedance value e.g. 75 ohms rather than the 45 ohms at 100MHz (for a single turn)?
Would it be possible to identify the type of connector that plugs into the board? Buy an inline plug and socket and make up an extension you can plug in. I can't clearly see the connection at the jack socket, but it might be possible to make up a longer replacement cable in the same way.
Often the loop is just to stop the ferrite from sliding up and down the cable! But it should really be as close as possible to the source of RF energy — the circuit board — rather than half way down the cable.
Personally, I would open it and take out the loop to gain extra cable length. Re-attach the ferrite as close to the board as possible and secure in place with a cable tie if necessary to prevent it sliding down the cable.
If you find you have an RF emissions problem later on you could replace the original ferrite with a larger (higher impedance) one if necessary.
Technical Editor, Sound On Sound...
(But generally posting my own personal views and not necessarily those of SOS, the company or the magazine!)
In my world, things get less strange when I read the manual...
Andy, the cable is carrying a 50Mbits/s signal, so I wouldn't want to extend it. If you could do that, it would be just as easy to simply make up a longer cable. And it's easier to get someone who has the right crimping/cable insertion kit to do that rather than try and do it yourself.
Still don't know why they couldn't have used a slightly longer cable!
Last edited by Wonks on Fri Jun 13, 2025 2:59 pm, edited 1 time in total.
Inductors in series add, just like resistors, in terms of inductance (unlike capacitors, where capacitance adds when you parallel them) so I would have thought, given the primary role of this bead is just to suppress radiated interference, that a single bead with the cable passed through would suffice. Otherwise two beads should, in theory, have approximately the inductance of one bead with two turns, at least for this application, which is not a tuned circuit or anything where the exact inductance matters much.
Frankly even without the bead its unlikely to be an issue, it was probably fitted to ensure FCC certification rather than to fix a specific problem. Heck, a lot of USB3 cables radiate enough energy at 2.4GHz to cause wifi issues as it is.
Nor are you dealing with a transmission line where you need to ensure an impedance match to avoid reflections.
A cheap and cheerful way to check interference is to purchase a UVK5 radio, for the ridiculous sum of under £20. These have a highly sensitive front end that couples to a rubber antenna and work over a pretty wide frequency range; certainly they will pick up stuff from 100MHz and up to around 1GHz surprisingly effectively (they are very useful for checking wireless mics and stuff).
They will easily pick up e.g my waveform generator set to 60MHz with a little bit of wire poked into the front BNC connector, from the other side of the house. Some rather nice free firmware turns them into a serviceable RF spectrum analyser. Yeah, they are not exactly Rohde and Schwartz test equipment but... they do definitely pick up radiated crap.
The GK5 kit is now all fitted and the ferrite bead has a single pass. The lead was just long enough to reach to the output socket with just a bit of slack.
I only had Arkieboy's GM-800 to test it with, so I know the synth pickup works with it. I know the guitar side works without the GK pickup gubbins working (it's wired so inserting a jack plug into the normal jack socket disconnects the passive pickups from the GK electronics to keep the impedance the pickups see just as before). But because the GM-800 was set up for synth-only output, I couldn't tell whether the GK gubbins added any noise to the straight guitar pickup sound.
When setting up the GK hex pickup sensitivity on the GM-800, you can hear the straight hex pickup sound, which was very 'plinky' - but that's not surprising given how close it is to the bridge. But it didn't come over as being noisy.
Arkieboy will be getting at back at rehearsal tomorrow, where he'll reinstate the GM-800 in his rig alongside the VG-800 where he can break out the guitar signal and hopefully see if that sounds OK.
All is working perfectly. Acoustics are clean without excessive noise, regular guitar sounds fine. I had a touch of instability on the GR-300 emulation in rehearsal but when I got home I realised I'd not set the string sensitivities - the GK5KIT6 has much more poke than a GK3KIT through the serial convertor. Having set them now, all is good.
Also Wonks put a green Sharpie to great use touching up the guitar body and kept his black Sharpie well away from the headstock so things are shiny again!
I'm much happier overall with the GK Serial setup than with the 13 pin. Cable is much better and the connectors feel less fragile and more reliable.
