Documentation on Katana 50 FX Loop

Started by Romulusrex, August 24, 2023, 08:16:09 AM

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I've seen a bit of talk about this, and it seems at one point ColorMaker managed to successfully mod a katana 50 to include an fx loop, but since then they've gone silent on their youtube channel and in the forum, so I thought I'd open a new thread and see if we can work something out. To add a bit of value to the new conversation though, I did manage to find the katana 50 mkii service manual, as well as the 100 mki one.

As many guessed, it seems to be the unpopulated CS6 connectors that go to the send/return for the fx loop in the katana 100:

Here's the same drawing for the katana 50 populated up to pin 9:

So, question is - does anyone here know how to do this stuff?

Here's the full service manual files also. Can't find 100mkii unfortunately, but I don't think there's any changes to this part of the circuitry...

Has anyone got any good ideas about how to proceed from here? It'd be awesome if we could add fx loops properly. Alternatively if ColorMaker or anyone else who's succeeded want to let us know what they did differently, that'd be awesome too!


Colormaker wants $$ to share the info

And after performing this FX Loop MOD, good luck obtaining Service from any repair center today, as most will refuse to work on "modified Katana  amplifiers".  And given that bulk of Katanas are owned by young inexperienced guitarists, results in a situation with high likelihood of failure , as many have zero experience with electronics.  Katanas tend to fail if care is not exercised during disassembly/reassembly - just google search on  "Boss Katana - no sound"


You won't be able to use the Kat 50 empty component spaces on the board as the Send/Return is disabled in the firmware on the Kat 50.

I am sure the mod was simply cutting into the power amp line signal in the circuit board and installing a basic send/return
(which does not use the send D/A and return A/D converters, nor any software control over the levels).

Its really a job not worth the time & effort,
 if you were to send the katana 50 away to be mod'ed and returned,
 it would cost more than the value of the Kat 100 that you should have brought instead.   ;)
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Quote from: gumtown on August 25, 2023, 02:50:32 AMif you were to send the katana 50 away to be mod'ed and returned,
 it would cost more than the value of the Kat 100 that you should have brought instead.   ;)
Of course, I realise it costs a fortune to pay anyone else to do anything, but I thought the point of this forum was about working stuff out yourself, hence the DIY tag.

Can you elaborate on what you mean by a basic send/return before the power amp? I've done a lot of electronics, but not with audio before. I assume it's not just as simple as wiring in two female jack sockets into the power amp line-in cable?


Just google adding FX loop to amp , image search reveals a diagram .

While we provide DIY diagrams to add missing features on gear - in this case of Katana 50 FX Loop, its a world full of plentiful used  Katana 100 amps  available, skip the drill and soldering iron and high risk of failure,  best path is acquire a Katana 100 - sell Katana 50 , fund a used Katana 100  - would be lower expenditure of labor , tools, and better outcome with a usable fully adjustable Send & return level FX Loop in Katana 100

Pat the Brat

I use Strymon Reverb and Delay stereo pedal and i wonder if it would it be possible to have the Katana FX Loop modified to be Stereo?
Objevtives being when the stereo output of the last pedal is inserted in the modified FX loop, the stereo feed would be availalble through the REC OUT/HEADPHONES output? (which seem the only stereo output on the Katana)

I understand the sound from my Katana speakers would be mono (duh!) but this should give me possibility to have my pedals stereo feed properly placed in the sound chain and available for recording in Logic and (i assume) to be fed to a P.A in gig situation.

If this mod is possible, would it impact the overall sound quality now that pedal output goes through the amp circuitry and not directly from the pedal output?

Hope those are not a dumb questions.... and needless to say that i wouldn't dive in this modification myself.
(although this post is for the Katana 50, i have a KTN-100 in case that change anything to the awnser)

Thank you for your great collaboration!


Rec Out Headphones on all my Katanas is Mono - and very disappointing
( Big Reason I use Fender Mustang GTX , or NUX Mighty Space - both amps provide genuine Stereo FX on their Headphones outputs

Pat the Brat

That's too bad, indeed.
Thank you again for the reply


Hi all, just to say it's really not that bad adding the fx loop to the katana 50. I did it back in October shortly after starting this thread. Lot's of people saying it's super complicated, I'm not sure why.

I did it twice actually, the first way is much easier, but was after the main amp so you can't change the volume of the loop which I didn't want. So I then changed the position of the loop to being before the main amp.

1st version: easy access, lot's of space. FX loop after the main amp. 1. open up the amp 2. identify the cable shown below 3. cut cable 4. wire in fx loop in and out jacks at each end of the cut cable (you can solder or use whatever connecter you like, I used wagos at first while testing) 5. job done!

2nd version: more difficult access, but this is before the main amp so you can turn the volume of the loop up and down using the master volume and power control on the amp. Same steps as before, but the cable is more awkward. It also has some super sticky stuff around the edge which is difficult to get off. Just try to be gentle with it. I didn't take as many pictures this time round because I wanted to get it done mostly, but the cable to cut is this one below...

Don't do it if you're not a practical person, it is a bit fiddly, especially the second version before the main amp. That said, I'm certainly not an electrical engineer myself (as I'm sure lots of people will point out) but it wasn't very difficult. I'm not sure why so many people talking about this are suggesting it's rocket science. You're just splicing into a cable and adding two jack sockets.

Anyways, good luck!