Hi guys. My Mod Duo X has a very strange issue - in main outputs 1 and 2 I get sound that is just bypassed from inputs, completely ignoring the pedalboard. Original input sound still goes through even if I remove all the pedals and connections. Even master volume with a right endless knob is ignored, as well as outputs gain.
Meanwhile, sound from the headphone jack behaves normal, responds to changes in pedalboard and master volume.
I have already tried reinstalling the 1.13.5, factory reset with 1.13.4 and upgrading again to 1.13.45 from the web interface, and it’s still the same.
That’s really wierd, considering that I remember that it was mentioned that headphone output mirrors main outputs no matter what, and does not have any separate representation in software, except for CV usage.
Basically, this problem renders device useless, and I have no ideas on further troubleshooting…
Hope we still have somebody alive here to help.
Hmm. After disconnecting everything including power and usb for 10 minutes device is kinda back to normal. But it is not clear to me what is the root cause.
I joined this forum because I’m having the exact same issue. I spent 3 hours yesterday trying to get any effects at all out of the out 1 and 2 from my newly acquired MOD Duo X.
Headphones works as expected with the effects presents. But no matter what I try, there simply is no effects on the Out 1 and 2.
My last resort before totally out of ideas is that, since the Duo X has balanced outputs and my XR18 mixer also has balanced inputs, to try to use balanced cables between the Duo X and the XR18.
I have so far only used regular unbalanced 6.3 instrument cables.
Can perhaps someone with more technical knowledge tell me if this can actually be the issue? The only thing I can think of is that the unbalanced cable is somehow shorting the balanced in/out between the Duo X and XR18, and therefore removing the effects. But is this even realistic of me to think? Why is the clean signal going through with not even a touch of effects in signal?
(Not currently at the Duo X, so need to try this later…)
Those are not engaged, but engaging them let’s me pass the audio through to OUT 1 and 2 at least. So the outputs at least works, but not through any effects.
Edit: The hardware buffer switches has no effect at all. See below for update.
Ok, that’s a good test at least! and gives a bit of an idea where in the signal path there is an issue.
Not that I have an immediate explanation or solution though …
Unfortunately balanced cables from out to my mixer did not make any difference. But I’ve narrowed it down some more I think.
The hardware bypasses has no effect at all. It is as the hardware bypasses are stuck on indefinitely.
Any ideas how to continue troubleshooting? Is MOD audio still active/alive and offering support…?
My issue is exactly as OP described in the first post and I’ve taken same steps without change.
Pretty bummed currently since I was really looking forward to using and getting to know this device…
Another desperate thought. Can non-grounding cause the hardware bypasses to not disengage?
According to the manual the hardware bypasses are enabled when the MDX is powered off and supposedly disengaged when a pedalboard is loaded. It seems that the relays are never disengaged in my case.
Looking at the schematic for the MDX bottom board I see that the hardware bypass relays have a ground connection.
The thing is. I live in Sweden, and here it is not uncommon at all that older houses still have some rooms where the wall sockets are not grounded, and some rooms (bathroom and kitchen usually) have been modernized with grounded outlets.
I’m currently running my gear in one of the old rooms without the grounded outlets. Leaving me to think that perhaps, perhaps this can cause the relays to not disengage. Can it be that simple? That if I connect my gear to an grounded outlet, it should help with disengaging the hardware bypasses?
To my understanding the MDX relies on grounding (reading about the different ground loop issues and touching the input with ground from the output in some thread I read etc.)
Is there perhaps a way to manually force the hardware bypasses to disengage? Since the software buttons do not work or do anything currently in my case.
In general, for your issue, if you go to the device settings and activate/deactivate the Hardware Bypass, can you hear some clicks coming from the device itself?
If you don’t, you can already pinpoint the issue to the relays not engaging.
Speaking of ground loops, you might try to eliminate one by powering the device from a powerbank.
And I double jon’s mentioning of the clicks and a whole idea of relays being related to the root cause. I have suspicions that i did not have clicks when issue was reproducing for me, but was not sure (because idea of that appeared only when device started working with a click, and I could not tell if I was not just paying enough attention before)
Relays, btw, can be switched with a magnet strong enough as I’ve seen at lockpicking videos:
Interesting, that there are two relays, and issue happens for both channels in the same time. Therefore it should not be physical relay problem, but rather something that controls them got confused, as it is unlikely that they both broke simultaneously.
Btw, if you tried to power off device for a long time as me, did you keep the power switch on to drain all the charge?
I will test the grounded outlets later when at the gear. But it will probably make no difference is my gut feeling. I will report back later.
I will listen for clicks when engaging the software bypasses. I already did so yesterday because I read in some thread that I would be able to hear a click. But I didn’t hear anything yesterday… Then I was in the firmware release notes that read an earlier firmware allowed for “silent bypass enabling” and thinking that was the reason I didn’t hear anything. But that note was perhaps regarding something totally different.
I am running the latest firmware right now, and I definetly hear the sound. (when powering on the box) Maybe it is less loud, I do not know, but it is there for sure.
UPD:
Clicks are happening when i click bypasses in webui as well
I also have a naive idea that maybe it is the power supply, sagging under the load and not providing enough voltage for switching. But probably computing module consumes much more.
Yeah, it seems highly unlikely that both relays break at the same time…
But currently I’m out of ideas. You reckon replacing the relays with new ones would solve it, or is this more likely an side effect of another issue in my device?
Do you think a usb ground loop could be a potential cause?
It is not a dead end, I think, you always can go hardcore.
And I guess that before replacing stuff you might need to gather more info with oscilloscope/multimeter, without doing any really invasive procedures.
And as soon as we actually have schematics, it is much more doable.
From top of my head it would be:
Find this relay datasheet, and determine which pins are responsible for what and map that to MDX schemattics.
Knowing pinout - find how controlling signal behaves, is relay even getting proper command to open/close? Is it stuck permanently in one state?
If relay gets enough voltage to work
Look if all condensers are fine - I am not a seasoned electronics expert, but for what I know these guys are usually the first to die of age or just because they like toi.
For example - you see that controlling signal is fine, in that case it is relays or their power supply (or maybe some condenser is dead and does not handle consumption peak during switching) .
Or for example you see that control signal does not change, in that case changing relays would not help,.
In the almost-worst case, if there would be no other options - you might be able to get rid of the relays at all and hardwire connections in a permanently “on”, no-bypass state, loosing the hardware bypass ability. (I actually never used it, so it would be feasible for me for example). Bypass the bypass, in other words.
P.S. Also before resoldering stuff, I would try to make sure that everything had been dischaged completely, including condensers, maybe even my shortening them out with resistors to dischage, because from my gut feeling (and based on fact that both relays are refusing to work and long poweroff helped me) some chip that controls the relays got confused, and full discharge of chips sometimes helps to restore them to a normal state.
Leaving the physical power switch on (for draining the residue power) without anything else connected to it for 4 hours had no effect at all (+ another 14 hours until today).
There’s still no audible clicks when engaging/disengaging the hardware buffers. And no clicks when powering on the unit.
What I found out is that the person selling the device to me sent me an underpowered power adapter with 12V and only 1A center positive.
But even though changing to a power adapter with 12V and 2A center positive, and then factory restoring it followed by updating to the latest firmware version, also had no effect what so ever on anything.
So now the question is if using an underpowered power adapter have caused physical damage to my unit? From what I read it shouldn’t physically damage things, only that things can misbehave. Is this correct?
Edit: the seller offers me to refund part of what I paid for it and sell it to me as an “for repair device”. @ignis32 and @jon, what are your seasoned thought on this? Do you think it is repairable semi easily, or can what I mention above have caused micro chips etc. to take damage and we are talking about replacing actual circuit boards and whatnot inside it?
I guess here lies the answer to your problem. We really recommend 2A for the devices (as you can read here). I can tell you from some experiences on my side that I talked with the team, anything below 1.5A it’s not really reliable, even if sometimes it works all good.
It’s not impossible that the use of that power supply somehow damaged something that takes care of those relays.
Normally, no, but maybe the repetitive use of that messed up with something. You may still be able to recover it somehow, but I’m not really skilled enough to tell you any idea from the top of my head.
I would say that yes, although I can’t offer you much help. I would go back to the multimeter/oscilloscope and check if every component of those relays circuit is doing what it should do.
