UPDATE:

I just tested another cheapo Y-cable that i managed to grab.
It introduced the exact same issue.

So i can rule out the cable issue.

One interesting point - I just noticed that if i minimize RME Fireface mixer, the soft clicking noise is almost eliminated but there is still a noise floor and the signal is still low (hence bad signal-to-noise ratio).
Also harddrive seeks seem to introduce some noise.

Looks like shielding issue; the cable picks up interference from the surrounding electronics (flash elements on screen, harddrive seeks)

I was quite sure the Mogami cable i use "should" be built of high quality materials, including the shield inside.
But maybe that's pure limitation of the unbalanced connectivity. Go figure...
The Mogami cable i use now is 12 feet long. Not too long but not extremely short either.

One more thing - regarding the low signal volume:

I read somewhere:
"..Balanced connections reduce noise but the signal level WILL be less if the recording interface is balanced and you use an unbalanced signal.."

And from my RME FF400 guide:
"..The Fireface has balanced line inputs as 1/4" TRS jacks on the back of the unit.
The electronic input stage is built in a servo balanced design which handles unbalanced (mono jacks) and balanced (stereo jacks) correctly, automatically adjusting the level reference.."

What do you guys think ? Is there any workaround for this issue ?

From what you say, you have the correct type of cable and are connecting it up correctly. The line input jacks on the FF400 are true differential inputs, so will handle either balanced or unbalanced signals without quality loss. I'm assuming you have tried connecting something like a portable CD player or a mobile phone (both via a 3.5mm to 6.25mm adaptor), and respectable levels and quality are received at the FF400. It would be normal to have to increase the FF400 line input gain above the default +4dBu setting.

I've never seen the type of problem you describe with a keyboard, but I was once called in to diagnose something similar on a computer motherboard 3.5mm headphone output. The motherboard would drive headphones without a problem, but gave virtually no signal when feeding a hi-fi stereo input. It turned out that the motherboard monitored the impedance of whatever was connected to its jacks and used the result to make unwanted adjustments to what was sent or received from the connector. I demonstrated that by using a Y-splitter and plugging both the headphones and the hi-fi into it, a strong signal was received at the hi-fi. Rather than leaving headphones squawking on the floor, I made up an adaptor cable with a couple of 33 Ohm 1W resistors soldered from the signal lines to ground, and all was well.

I'm not saying that this is necessarily your problem with the keyboard, but in order to break the problem down, I do think it's worth experimenting with a 6.25mm TRS Y-piece feeding the headphones and the FF400 inputs at the same time. To ensure that you outwit the keyboard, I would use an external Y-piece for this test rather than use both the keyboard's headphone jacks. If the test makes no difference, we can take it further from there.

First, you can't use a TRS on a TR connector. If you have TRS to TR connection to make, use a mono TR cable at both ends.
Aux out and Line out aren't properly amplified for headphones. So your solution would be to use the realtime mixer of the FF400
Connect the keyboard line out to the Fireface 400 line-in inputs and in totalmix make sure those inputs are redirected to the FF400 headphone output.
Just come back with the results and we will see what to do next.

BTW, if you want to connect more than one headphones to the FF400, use the line outs to a headphone amp and assign it in totalmix acordingly

That is indeed an expensive Insert cable. All other things being equal, I would have also expected that to work as you intended.

From a quick scan of the manuals it appears the YDP-163 is equipped with a USB port for a variety of uses, including; "as a controller and/or sound source with a variety of music creation applications." And according to the Computer-related Operations guide for the YDP-163, "You can record your keyboard performance as audio data to a Music Production software on your computer", or "you can record your keyboard performance as MIDI data", using the USB port. You may, or may not, need to install the correct drivers for it to work properly.

Please let us know if there any new developments.

Good luck!

The snag here is an impedance mismatch - the keyboard output is design to drive 8-16 Ohm headphones paralleled at a fairly high level - common requirements for sales to schools. The interface is expecting a high impedance load, so your keyboard is seen as an almost short circuit - which lump loads the input circuit drastically reducing the available gain - most of the keys output is lost, so you having to apply too much gain, which lets the very small (usually) hash on the signal line from the keyboard become a problem. First thing I'd try is a proper DI box - where there is a transformer in the circuit. These usually respond better to very low driving impedances than a solid state device.

Remember - expensive cable is sold under close to false pretences -

Looks like a great high quality cable to capture the great sound of my piano.

Cable is a passive component, and cheap cable performs just as well as expensive cable. Hence why the cheap insert cable, which is exactly the same as the expensive ones. Try a cheap DI first. One thing to watch out for is that these keyboards rarely record very well. The frequency response is optimised for the small speakers they have and rarely sound convincing in a recording. The noise floor is masked in the headphones and missing from the small speakers - plug into a wider bandwidth device and you start to hear the things you're now discovering made worse by the mismatch.

Wow....
Many useful replies and tips here..
Thank you all so much for reaching out !
I will go through each idea you guys pointed out and try it out and will report back.

Highly appreciated,

Best,
Gary

Hey Paulears,

Your explanations sound most reasonable. I was quite busy since my last post here and unfortunately had not chance to bother with this issue; but now I do want to get going with this. So I am now looking for DI boxes but all of them convert Hi-Z to Lo-Z impedance which is the opposite of what I need in my case; assuming I understand the issue correctly now.

Could you advice me which DI box to begin with? Even an example of one capable to suite my needs would be good place to start....

Cheers,
Gary

Garygo, post: 460502, member: 51264 wrote: Hey Paulears,
So I am now looking for DI boxes but all of them convert Hi-Z to Lo-Z impedance which is the opposite of what I need in my case; assuming I understand the issue correctly now.

First, the headphone out isn't the best output to use, we should all agree on this to start with. But since you don't have a choice (unless you can record via the USB cable)
You will need 2 things, the headphone ouput is a stereo ouput so, you'll need a Y cable to split it in to mono signal (your insert cable can do the job), then you send those to a stereo DI (or 2 mono Di) which convert them to XLR sent to the Fireface 400 xlr inputs.

Start with the volume to zero and while playing push the volume up until it sounds good and you have healthy recording levels.
Radial DIs are the best I own.
This one seems to make sens :

Or this one :

Concur 100%

paulears, post: 456636, member: 47782 wrote: The snag here is an impedance mismatch - the keyboard output is design to drive 8-16 Ohm headphones paralleled at a fairly high level - common requirements for sales to schools. The interface is expecting a high impedance load, so your keyboard is seen as an almost short circuit - which lump loads the input circuit drastically reducing the available gain - most of the keys output is lost, so you having to apply too much gain, which lets the very small (usually) hash on the signal line from the keyboard become a problem.

Sorry, Paul, but this is completely wrong.

The standard headphone output of a keyboard can drive low-impedance headphones, but is quite happy driving anything of a higher impedance, including an open circuit.

The line input of an interface such as the RME FireFace400 performs best when driven by a low impedance source such as zero Ohms, and will happily accept the keyboard headphone output. Since the FF400 line inputs are true differential, they perform the same when driven by balanced or unbalanced sources.

None of the keyboard output is lost by connecting things in this way, but see my previous post about some devices auto-detecting whether they are driving headphones or line inputs, and altering their output characteristics.

Despite the above, use of a DI box may indeed be appropriate in this instance for acting as a ground isolator between the keyboard (probably powered by a cheap mains pwer supply) and the interface. I don't see it being needed for signal conditioning.

I had to pick up on this, as the thread could be read by many other people trying to connect a keyboard to an interface.

pcrecord, post: 460504, member: 46460 wrote: First, the headphone out isn't the best output to use, we should all agree on this to start with. But since you don't have a choice (unless you can record via the USB cable)
You will need 2 things, the headphone ouput is a stereo ouput so, you'll need a Y cable to split it in to mono signal (your insert cable can do the job), then you send those to a stereo DI (or 2 mono Di) which convert them to XLR sent to the Fireface 400 xlr inputs.

Start with the volume to zero and while playing push the volume up until it sounds good and you have healthy recording levels.
Radial DIs are the best I own.
This one seems to make sens :

Or this one :

How about Radial JPC? Trying to understand which one would be better suited?

Boswell Would you consider the JPC better equiped by design to help with a headphone amplified signal or a strait Di is ok ?

pcrecord, post: 460509, member: 46460 wrote: Would you consider the JPC better equiped by design to help with a headphone amplified signal or a strait Di is ok ?

I have several different Radial boxes, but not the JPC. This is mainly because I've not met PA or recording situations where I have suffered from hum or buzz that could not be solved using either other types of Radial boxes or ones of my own design. However, the JPC looks to be an excellent unit, and if I had to carry around a minimal number of DI boxes, I would probably include a J48 for instruments and a JPC for connecting stereo consumer gear.

In the case of the keyboard in this thread, my feeling is still that there is a signal level problem, and once that has been identified and dealt with, then to remove any remaining background noise, hum and buzz may indeed need something like the JPC.

Boswell, post: 456627, member: 29034 wrote: I've never seen the type of problem you describe with a keyboard, but I was once called in to diagnose something similar on a computer motherboard 3.5mm headphone output. The motherboard would drive headphones without a problem, but gave virtually no signal when feeding a hi-fi stereo input. It turned out that the motherboard monitored the impedance of whatever was connected to its jacks and used the result to make unwanted adjustments to what was sent or received from the connector. I demonstrated that by using a Y-splitter and plugging both the headphones and the hi-fi into it, a strong signal was received at the hi-fi. Rather than leaving headphones squawking on the floor, I made up an adaptor cable with a couple of 33 Ohm 1W resistors soldered from the signal lines to ground, and all was well.

There's a fair chance this is happening with this keyboard too, as it is a Yamaha. Lemme see if I have schematics...

cyrano,
Did you come up with the schematics for this keyboard? I am interested to read your take on this...

Sorry, mate. Nothing much on this Yamaha.

Your case just reminded me of another one, a while ago. In that case, the manufacturer admitted that there was something wrong with the output. Later on, I stumbled upon the schematics and found out what kind of IC was driving that output.