Korg X50 transpose 1 tone down randomly....

[Saltis]

Hi all !!

I am father to a 17 year old girl that plays synth in a band.
We bought a used X50 to her, some time ago.

In the middle of a performance the synth was transposing one tone down.
She went extremely upset as it was a competition and the performance was ruined.

We went to the shop where we bought the X50 and we could borrow a brand new one.

At the rehearsal today, it happend again (with the new one).
In the middle of the melody, suddenly the synth transposed one tone down.
She has not been changing any settings and she claims that she has not touched any buttons.
She says that it happens when the synth is connected to the PA but never at home.
She has a feeling that it might have a relation to the usage of the damper but she is not sure.


So...
Synth: Korg X50
Sound: Stereopiano mf/f
Problem: The synth transpose suddenly one tone down

Thanks in advance!

[X-Trade]

vibrations could cause some of the knobs to send out values.

I don't have my TR any more (same programs as the X50), but I think for that program when the knobs are in assignable mode (B mode) one of the knobs adjusts the tuning/pitch of the sound. I would check that and when performing make sure it is centred, or edit the program to turn that knob off (in the controllers page).

[Saltis]

I have talked to my daughter again.
This has happens 4 times and she is convinced that she has not touched the knobs on the left side.

Why only on stage and never at home?

She connects the analogue outputs to the PA.

[wendyl]

hi Anders

I have had the exact same problem with my X2-and on a gig too which was just awful-so I sympathise with your daughter

I found turning it off and on was the only thing to bring it back to normal but had to keep stopping playing of course.

I wonder if you have had any success in curing this problem? I haven't managed to sort it out yet. I also thought it was related to the damper pedal so i took it out but it still did it. I do think maybe it is a vibration problem-or a playing it harder related problem.

Anyway, I would appreciate it if you could let me know if you had any luck with sorting it out.

Wendy

[xmlguy]

She says that it happens when the synth is connected to the PA but never at home.
She has a feeling that it might have a relation to the usage of the damper but she is not sure.

You need a stereo DI Box. The problem is most likely an electrical ground loop between the PA and the keyboard. It's possible that the damper could effect the ground loop by electrically connecting the pedal to the floor or through her foot-body-chair-floor. Does she use the damper with a bare foot? The DI box should have a ground lift switch. It should be stereo so that she has the option of running stereo to the PA, when available. If you get a mono DI, then stereo isn't an option.

It's also possible that a static electricity discharge is occuring through the keyboard, but this is less likely than the ground loop because of what you describe.

Even if there isn't a ground loop, she should STILL have a stereo DI box when hooking to any PA that she doesn't own and control. By the way, ground loops can be dangerous and cause electrocution, particularly if there is a malfunction in the PA system. Someone can even be electrocuted when hooking up a cable from a PA into a keyboard or amp. Never fully trust that a PA system won't shock you. Even though this doesn't happen very frequently, it DOES happen. I have personally been shocked hooking up keyboards up to a PA, so I don't think I'm exaggerating the risk. You never want to make your body become a good conductor to ground, such as by holding any metal railing, stand, metal keyboard when grabbing an input jack to a PA - the shock can go right across the chest and put the heart into fibrillation with less than 1 amp of current. When you have a DI box, you can hook it to the keyboard, then let the soundman or roadie plug the PA into it, that way they get the shock if their gear is screwed up.

She has not been changing any settings and she claims that she has not touched any buttons.

Well that's a separate problem. She should be changing settings and touching buttons. The more she learns about the synth, the better she can make use of it in a band.

Is she afraid to learn how it all works? If so, that could greatly limit her potential to explore and to advance musically into synthesis. I know this isn't the primary reason you're writing, but I think that anything that you can do to encourage her to conquer any fear she has will be a great accomplishment. It's like helping a kid to overcome the fear of water by teaching them to swim one step at a time, rather than being thrown into the water. Being given a powerful synth like the X50 can be very intimidating.

[wendyl]

trust me xmlguy, when you're on a gig and your keyboard tranposes down a tone at any moment it chooses you are paralysed with fear that no knowledge of knobs and buttons on your keyboard could possibly cure.....

I think what Anders meant was that his daughter hadn't INADVERTANTLY touched any buttons to CHANGE the key not that she was scared of her keyboard. I kid you not however, I am now scared to death of mine and until someone can tell me why it's happening will be going back to my trusty Technics for future gigs.

[xmlguy]

Are you using a DI Box? If not, then you should be afraid. A DI box helps to protect your gear.

[XeRocks81]

I have had the same issue happen to me a few times recently. Just today, I was rehearsing with a band, playing through a small amp, not a PA, and I was already transposed 3 half-steps down. All of a sudden it changed the tuning without me doing anything other than playing.

[xmlguy]

I have had the same issue happen to me a few times recently. Just today, I was rehearsing with a band, playing through a small amp, not a PA, and I was already transposed 3 half-steps down. All of a sudden it changed the tuning without me doing anything other than playing.

Ground loops can occur just as easily with amps as with PA systems. I've personally experienced many bad effects of ground loops on amps, including receiving one hell of a shock from a keyboard attached to an amp with an internal short and floating ground. Static shocks can also cause strange behavior, particular in the summer when it's windy and dry. Without actually having a DI box, it's very hard to determine if a ground loop condition exists unless you know electronics and how to test for it. Static is also hard to determine because it's hard to know when static builds up to the point that you actually feel or hear the shock discharge. But if you are aware of these possibilities then you can observe any conditions that might contribute to the problem.

[Alex_G]

So I just happened across this forum and might be able to answer these questions, and a few others related to seemingly random changes occuring on the x-50.

A little background on the guts:
If you take it apart you will notice that the ground rail is actually an aluminum sheet running the length of the board. The purpose of this is to establish a common ground by which all circuits (controls, power supply, processor, etc) can be grounded. The ground is effectively the reference by which all other signals are measured (0V). If a circuit (say a control circuit) becomes temporarily disconnected from this aluminum ground, the circuit loses its reference, and can (will) send incorrect signals to the processor. These can range from key transposition to master volume, and many others listed on these forums.

Once any point is taken off ground, the processor is "confused," (charge has built up, ground is no longer 0V) and the only way to restore them is to shut off and turn on the keyboard, re-initializing the ground @ 0V.

The cause:
The keyboard is simply flimsy (I don't mean to knock it, I own and love an x-50 myself), and any sort of hard playing can cause these ground disconnections. The left side of the board in particular is very susceptible to this.

xmlguy's ground loop idea is certainly plausible, but I would say unlikely. The ground variations in a PA can be huge (100V+), which would fry any microprocessor (and your lips on the mic, as many of us can attest). Korg knows this, and designs circuits to be isolated from any outside signals (there is basically a one way "valve" on all the outputs to protect the board). Furthermore, I have seen this x-50 problem when I have been editing patches with only headphones and power plugged into the board, suggesting the PA is not the cause. I would guess that your daughter simply is playing harder when plugged into a bigger sound system (don't we all?).

The solution:
a. don't play so hard (or)
b. take apart the x-50 and reinforce the ground rail (the aluminum sheet). I put some polyester foam (extra padding from a case) underneath the sheet, forcing it to maintain contact with the circuitry on the top side of the board.


For whatever reason Korg wanted to make this board super lightweight. I don't really get why anyone needs a 4kg keyboard (or why it needs handles) but that's for another discussion. Since reinforcing my x-50, I have hammered away at it without any problems.

Good luck, feel free to PM with questions on the mod. It is by far the easiest "hardware" mod (if I can even call it that) I've ever done, on anything.

-alex

[xmlguy]

Alex, you very well could be right about pressure and flex. I use my X50 only on solid surfaces or on the second tier of my V-Stand, which is adjustable so that I can put the supports in a position that minimizes flex. On an X-Stand that is set wide, then all the pressure is distributed to the case of the X50 instead of being supported by the stand.

[Alex_G]

Yeah, I could never really nail down the exact move to trigger it (pressure vs. flex vs. jarring it). Having an adjustable stand would certainly go along way to get rid of the problem, that is actually a very good suggestion for someone who doesn't want to rip their board apart just yet.

This is an upper deck board for me when I use it live, and I've never had any issues then (as I don't have a strong attack that high up). Only when I put it on a low table, (or even programming it in my lap) do I see this. It is always when I inadvertantly play it too hard.

[keeverw]

Are you using a DI Box? If not, then you should be afraid. A DI box helps to protect your gear.

The output of the X-50 is a line-level output. A DI box is completely unnecessary, and the only advantage it might offer is a ground-lift switch, which might help eliminate ground hum if there is any.

And a DI box would certainly not solve her automatic transposing problem.


I have had this exact same problem by the way, and I don't know what's causing it.

I have played the keyboard hours on end in my garage, and the first time I took it to play at church through their PA, it did it in the middle of a song during rehearsal. You can just rotate the wheel to go to the next instrument, and then roll it back to the piano (or whatever you were originally playing) and it should go back to normal. But that is certainly not a permanent fix, because it still interrupts your playing.

The weird thing is it happened at the same point in the song the next time we played it. I am pretty positive I wasn't hitting anything but the keys at the time.


But no offense, as an electrician of 12 years and a musician and sound-tech of about 15 years, I promise you there is no possible way a DI-box could fix this problem.

[Alex_G]

Keererw, you may be confused about how a DI box works. The signal path from the x-50 is a line level, high impedance singal. A DI box receives that and outputs a balanced, low impedance signal to the PA (the guts are almost identical to an AC transformer). These are informally referred to as instrument level and mic level signals, respectively.

A line level instrument should always be run through a DI. Always. (You don't need a fancy, active DI, a $25 passive one will work great).

[xmlguy]

Are you using a DI Box? If not, then you should be afraid. A DI box helps to protect your gear.

The output of the X-50 is a line-level output. A DI box is completely unnecessary, and the only advantage it might offer is a ground-lift switch, which might help eliminate ground hum if there is any.

And a DI box would certainly not solve her automatic transposing problem.


I have had this exact same problem by the way, and I don't know what's causing it.

I have played the keyboard hours on end in my garage, and the first time I took it to play at church through their PA, it did it in the middle of a song during rehearsal. You can just rotate the wheel to go to the next instrument, and then roll it back to the piano (or whatever you were originally playing) and it should go back to normal. But that is certainly not a permanent fix, because it still interrupts your playing.

The weird thing is it happened at the same point in the song the next time we played it. I am pretty positive I wasn't hitting anything but the keys at the time.


But no offense, as an electrician of 12 years and a musician and sound-tech of about 15 years, I promise you there is no possible way a DI-box could fix this problem.

So you're saying that a DI box doesn't protect the gear, which is what I said above? Ground lift helps to protect gear. So does audio transformers or active electronics to protect from phantom power inadvertantly applied to the output of a synth.

Lets say the mixer has +48V phantom power on all mic channels, all mic channels are sent through a snake to the stage, then someone plugs an XLR to 1/4" adapter from the snake to the keyboard output. Is this something you'd want to try with your own keyboard? Many soundman prefer a balanced line level keyboard output, which the X-50 doesn't produce without a DI box, having groundlift and a pad is nice too. That probably why keyboardists and soundmen buy DI boxes for keyboards as well as for highZ instruments that need them for impedance matching and to get a balanced output for running through a snake.