Joyo PXL8 Pro Switcher

[Big Monk]

Ladies and Gents.

I have no schematic from Joyo as of yet but maybe the collective can help me out.

I found out the hard way last night that my Joyo switcher has an input buffer. Plugging the Monk Face prototype into it made the fuzz sound like shit. No cleanup, all high end gone. Took the fuzz and plugged it straight in and it was glorious as expected.

I already have a specially tailored buffer on the wah to play nice with the fuzzies and in searching the web, this is a known issue with the Joyo.

So, I opened it up and Lo and behold:



I’d really love to put the buffer on a switch but with the surface mount stuff, I may need to just pull it all out.

 

[Big Monk]

Without the schematic, I have a few ideas:

1.) I believe Omron G5V-1 and any of it's corresponding circuitry are used by the Mute switch to turn on the Tuner jack and Mute the whole switcher. So I believe that can safely stay or be ignored.

2.) I think my efforts in tracing should be centered around the JRC4580. That seems an obvious choice for the buffer.

3,) As a secondary choice, Q5 may need to be investigated as well, but I have not brought this to the workbench to try and read the case under magnification.

I have room next to the D Bank footswitch to put a short lever toggle for switching the buffer in and out if that is feasible.

 

[Big Monk]

Dear Diary,

Not sure if anyone out there is listening or cares.....( )

I did some exploratory probing () abd came up with a few things:

1.) The Omron relay is associated specifically with switching the input. I verified the switching contacts are attached to the tip of the global input jack. This makes sense as the switcher allows for Muting of the whole audio chain.

2.) The next jack over is the Tuner In and the Tip is couple directly to +IN2 of the 4580. So the input for the Tuner is buffer exempt as well.

3.) So the buffer first hits the send of the first loop. So I'll focus my area there. Good news is that there is a through hole film cap there at the input of the buffer and some through hole electros near where I imagine i'll find the output. This means i should be able to easily bypass the buffer on a switch.

BREAKING NEWS!!!!

Pin 7 of the 4580 is connected to a through hole 1uf electro. Which means my input and output path touched a through hole component and I should be able to use a switch to jump around that.

 

[SillyOctpuss]

Excellent stuff. Keep us updated this is definitely relevant to my interests. I've been looking at the joyo for a while. We'll to be honest I've been looking at the gigrig quartermaster but those are definitely not in my range at the minute. I'd be wanting to either remove the buffer or put it on a switch too.

 

[Big Monk]

This is the only switch I have right now so I am going to test with this and then replace with a short toggle when I order the new replacement jack for the broken Loop 1 send from Tayda.

As a side note, there is also a buffer on the send of Loop 8, but i am less concerned about that one.

 

[Big Monk]

Excellent stuff. Keep us updated this is definitely relevant to my interests. I've been looking at the joyo for a while. We'll to be honest I've been looking at the gigrig quartermaster but those are definitely not in my range at the minute. I'd be wanting to either remove the buffer or put it on a switch too.

The QuarterMaster is a major, major stepdown in functionality from the PXL8. The Quarter Master is basically just a fancy true bypass switcher. The Joyo is programmable and has trigger outs, tuner out and muting.

For the price, it's built like a brick shithouse as well.

EDIT: To expand on my statement, the Joyo has 4 banks of 8 programmable presets, 4 trigger outputs for amp switching, Strymon favorite switching, etc, a dedicated Tuner in, and a Mute switch. Obviously the Quartermaster does have flip-flop capability over the Joyo, but on the used market or even brand new, the Joyo is pretty extensive in it's capabilities.

Be aware that even the narrowest flat plugs are unlikely to work on this as the jacks are so close together.

 

[Big Monk]

Here’s a quick question for anyone tuning in:

I was planning on making special cables with pull-up resistors across the Tip/Ring of a TRS plug to kill the lag when using the trigger outs on the Joyo as favorites for my Strymon pedals.

Since I’m inside and soldering anyway, any reason not to just solder the resistors directly to the jacks inside the switcher?

 

[swyse]

I have no idea about the resistors from a proper protocol standpoint, but I thought this thread was interesting and I enjoyed my read.

 

[Big Monk]

I have no idea about the resistors from a proper protocol standpoint, but I thought this thread was interesting and I enjoyed my read.

The requirement to reduce the switching lag when using the triggers as favorite switches for the Strymons is to tie a resistor from tip to ring on a TRS plug AT the Strymon.

It seems functionally equivalent to simply strap a resistor AT the trigger out jaclnon the switcher.

I don’t know. Can’t hurt to try!

 

[Feral Feline]

I don't understand how adding a resistor will reduce lag. I would've thought it would introduce more lag.

 

[Big Monk]

I don't understand how adding a resistor will reduce lag. I would've thought it would introduce more lag.

It’s my u derstbading that with the digital switching happening between the switcher and the Strymon, that a pull up resistor is required to eliminate any switching lag.

Won’t pretend to fully understand the solution in this case.

 

[Big Monk]

Welp, it’s wrapped up:

 

[Big Monk]

@Feral Feline Thinking about the pull up resistor thing a bit more.

I think the issue is that the trigger outs of the switcher, which on the Joyo is a lot similar to even the more expensive options like Boss and GigRig, are at a different (higher) potential than the Strymon. The pull-up resistor minimizes the delta V, which is the cause of the switching lag.

 

[Feral Feline]

Okay, that's starting to make more sense now. Thanks.

I'll have to read up on this stuff a bit more, and the Delta V.

 

[Big Monk]

Buffer bypass is a total success.

I was certain I messed the whole thing up at first because there was a TON of noise with the Fuzz in a loop and the buffer on but I then switched in my Paragon Mini and there was only a marginal change and mo noise.

I still need to test the digital switching lag on the triggers but the buffer bypass is good to go.

I didn’t realize that noise was also an issue with high impedance into a Fuzz Face but now I’ve heard it for myself.

 

[Big Monk]

So after some testing, the El-Cap is still exhibiting switching lag.

The Flint is not.

So I’m fashioning a makeshift TRS cable with an additional 470k ohms to see if that improves or worsens it.

If it improves it, one of two things is occurring:

1.) The resistor needs to be at the plug going into the Strymon;

2.) 470k ohm on the jacks of the switcher was not enough.

 

[Big Monk]

So, The patch cable with the extra 470k resistor reduced the lag on the El-Cap.

This is not definitive though, as I'm unsure whether it's a combined 1M that is helping, whether the 470k on the switcher jack is even working at all, etc.

I'm going to run a quick test this week and put 10k, 100k and 1M on 3 of the jacks to test whether the hardwired resistor inside the switcher is working and what value works best.

Worst case scenario, I'll just make some cables up. I was hoping the resistors wired internally would work so I did not need anything special but I'm not too concerned if I have to.