[KL] Signal Noise PC3K8

['David Berriman' [e-mail] [KurzList]]

Hi. I’ve found that with certain chords, my PC3K8 gives off noticable signal noise, buzz, etc... I kept trying to different chords and bingo, I found one that worked without the buzz.

Is this a problem with the keyboard? Should I have it serviced or should I make sure to use only the right kind of cable. And if it’s just the cbale, PLEASE let me know what it is so that I can go get a couple more in varying lengths.

Dumb question, I know. Thank you.

Dave Berriman

[[e-mail] [KurzList]]

Question is a little vague. Troubleshooting is always divide and conquer.

So I would be asking:

Is this an effect? Is the KFDX just doing its thing? Switch it off until you find the cause. Select Patch 999 which does not use it.

Next, are you using the phones, master or digital out? Which outputs can you hear the fault on?

Try the phones first, can you still hear it?

Ringing on ALL outputs can be caused by MIDI loop. With patch 999, and go Master / Utils / Voices press a signle note, you should see a single "block" on the screen. More than this and you have a loop. 999 is a single monophonic voice. So double blocks means double triggering. If you unplug your MIDI cables and the ringing goes, this would also indicate a MIDI Thru is active somewhere downstream routing PC3 notes back to the unit, causing a second note to fire, causing phasing issues between the two notes in the audio.

"Digital" ringing will be a clock mismatch between the PC3K8 and your DAW audio interface. The PC3K8 requires an incoming SPDIF signal to clock to, and you have to adjust the Master / Output / Digi Out settings to get the PC3K8 to track incoming SPDIF. Get that wrong, and you will get all manner of artifacts in the audio.

If you cannot hear it in the phones, but you can hear it from your DAW/Mixer then the issue is not in the PC3.
Audio ringing can also be caused by phasing through your outboard. If not look at your outboard carefully. Have you pathed the audio directly and ONLY to your outboard mixer, or are you sending via more than one route (subtle but possible)? Are all but a single stereo route disengaged? Zero Auxes. For example, a Buss or Aux routed out and back, an bypassed external processor, all cause issues. Any EQ or Phase swapping on that can cause issues.

The effects you describe can also be caused by poor stereo pathing - are you running your audio hard L and hard R into yoru DAW, or into a mono stage? Phase cancellation can occur easily if you attempt to run a stero unit into a mono system. Unplug one lead, if using a Mono system.

Do let us know if you can narrow the question down trying these things out.

[[e-mail] [KurzList]]

And in my other reply, I am assuming you have covered the extremely basic checks off?

- Volume about 75% of the way up?

- Master and Aux Cables are "balanced" TRS style?
Note - an unbalanced "guitar lead" CAN badly affect or kill your audio, depending upon what you are connecting to...

- Mixer has bal/unbal detecting TRS inputs?
Check the manual. A clue would be if you are having to push the gain right up to hear anything at all on the receiving end, you are essentially listening to a massively phase cancelled audio signal and some earth noise, caused by non-sensing input on your mixer. You can solve this by making up your own TRS to TS lead, leaving the R disconnected. TRS end goes to the PC3, TS end to mixer.

- You have confirmed the cable works in another situation, and is not faulty?

- You have tried an alternate lead, just in case?

- Movement of the physical socket does not affect sound (which would indicate a physical socket fault).

etc.

[[e-mail] [KurzList]]

And in my other reply, I am assuming you have covered the extremely basic checks off?

- Volume about 75% of the way up?

- Master and Aux Cables are "balanced" TRS style?
Note - an unbalanced "guitar lead" WILL kill your audio, you have to use a TRS to TRS lead.

- Mixer has bal/unbal detecting TRS inputs?
Check the manual. A clue would be if you are having to push the gain right up to hear anything at all on the receiving end, you are essentially listening to a massively phase cancelled audio signal and some earth noise, caused by non-sensing input on your mixer. You can solve this by making up your own TRS to TS lead, leaving the R disconnected. TRS end goes to the PC3, TS end to mixer.

- You have confirmed the cable works in another situation, and is not faulty?

- You have tried an alternate lead, just in case?

- Movement of the physical socket does not affect sound (which would indicate a physical socket fault).

etc.

[[e-mail] [KurzList]]

[[e-mail] [KurzList]]

Lawrence, no. Not on TRS outputs.

T + R = 0. Because R = -T. Therefore T + (-T) = 0.

That's kinda the whole point of a balanced send. So if you plug a TS lead to a TRS output, you get 0 + noise, at the other end.

But you are probably thinking of TRS inputs, which may be unbal/balanced. They do this by typically earthing the R, leaving you with T - (-0) as your input signal, ie, just T which will be half the voltage you would have got had you summed T and -R.

[[e-mail] [KurzList]]

Aagh! My bad. Let's try that again!


If you connect TS into a TRS output, R earths, in theory leaving T. You just lose half the voltage on the input to the next stage. Balanced inputs invert R and add: so your signal = T + (-R) or 2T (since R is = -T).

However, theory aside, I have had situations where the Kurzweil would not work, plugged into downstream systems, and it was resolved by custom TRS to TS leads. I have a number of effects procssors which also have odd anomalies and need R disconnected as opposed to earthed.

Given a choice I would run TRS to TRS and a DI box.

And if by some bizarre mistake you connect T and R you will get 0 + noise...!

['David Berriman' [e-mail] [KurzList]]

Thanks for the replies. Balanced TRS cables is the right idea. Clean as a whistle now. Thank you.


From: ***@yahoo.com [KurzList]
Sent: Monday, December 04, 2017 3:07 PM
To: ***@yahoogroups.com
Subject: Re: [KL] Re: Signal Noise PC3K8


Aagh! My bad. Let's try that again!


If you connect TS into a TRS output, R earths, in theory leaving T. You just lose half the voltage on the input to the next stage. Balanced inputs invert R and add: so your signal = T + (-R) or 2T (since R is = -T).

However, theory aside, I have had situations where the Kurzweil would not work, plugged into downstream systems, and it was resolved by custom TRS to TS leads. I have a number of effects procssors which also have odd anomalies and need R disconnected as opposed to earthed.

Given a choice I would run TRS to TRS and a DI box.

And if by some bizarre mistake you connect T and R you will get 0 + noise...!