Humming when run over MIDI

[ceasless]

Hey all! First, let me just say what a privilege it is to be playing a Linnstrument! It's as awesome as I thought it would be.

So awesome, in fact, that I felt it deserved a partner in hardware that could keep up. In terms of processing inputs, I didn't find anything more powerful than VAST when it comes to hardware. Now there is a Kurzweil Forte to go with the LS. Time for some FUNs!

Yet I noticed yesterday that triggering a pad on the LS causes audible crackly distortion in the Forte. I can trigger this just by pressing a pad. A crackly-buzzy humming starts immediately. I tried switching MIDI cables (didn't work) and trying other MIDI sources (MPC; didn't cause the distortion).

This distorted hum occurs also directly out of the headphone jack on the Forte. From theses tests I my preliminary conclusions are: this comes from the LS (didn't happen with the MPC) and they are not related to later stages of the routing.

I ready about some users reporting humming here: viewtopic.php?f=263&t=458870&p=6406828& ... m#p6406828

But I don't know if this is the same thing. Mine is audible through an attached sound module, rather than from the surface of the LS.

Does anyone else have some ideas?

[Roger_Linn]

Hi ceasless,
I'm glad you're enjoying your LinnStrument. A brief recording would help to identify the problem, but my guess is that LinnStrument's high volume of expressive MIDI data is overloading your Forte, which tends to occur more on hardware synths. On the LinnStrument FAQ page, there's an FAQ giving some helpful tips on ways to reduce the MIDI data density. It's the 3rd FAQ under "Troubleshooting". Also keep in mind that the standard presets on synths are optimized for the on/off switches of MIDI keyboards, so for example your selected preset may be expecting pressure data only when you press a key hard instead of LinnStrument's full pressure range from light to heavy touch. Turning off LinnStrument's pressure sensing may solve the problem.

[ceasless]

Hey Roger,

I had ruled this issue out because it responds properly and without noise when routed over USB without any adjustments necessary. I'm also only in single channel mode at the moment.

MIDI handling also isn't mentioned as a constraint in the setup instructions for earlier model Kurzweils that is on the LinnStrument site, so it would be a bit of a head scratcher if the Forte had issues in that regard. Though, now that you mention it, I'll try it full-on MPE with ten fingers and six toes over USB to see how it handles.

By the way, the LS is connected directly to the computer. The Kurzweil is plugged into a Furman PL-8CE -- I haven't always had the best power conditions in my studio. I wonder if it could be a small disturbance in the force related to balanced power cables in my setup? That's a new factor here.

[Roger_Linn]

Please post a brief recording. "Hum" can mean different things to different people. To me, it only means a constant low frequency AC 50/60 hz tone.

[ceasless]

Sure thing. Describing sounds with words has never been an accurate form of transmission anyway.

Here is a short video on Google Drive: https://drive.google.com/open?id=0B1qZr ... mNfY1l5LTQ

I've pumped the trim on the audio interface in order to get a better recording, so this is not the "normal" level for the distortion. But it is audible enough to be heard on headphones even with less insane gain staging.

Thanks for your help!

[Roger_Linn]

I hear the buzzing sound when you play in the recording. Questions:

* The noise occurs in the phones output of the Kurzweil, so it must be coming from the Kurzweil and nowhere else. If this is a recording of the Forte's output, why is the Forte producing no instrument sound when you play?

* You mentioned that all works fine when routed over USB, so I assume you are connecting LinnStrument directly to the Forte using a MIDI cable. I assume also that when you connect via USB, you are connecting LinnStrument via USB to computer, then computer's MIDI interface to Forte's MIDI In jack. Is this correct?

* What happened when you turned off LinnStrument's sending of continuous X, Y and Z data as described in the FAQ I gave you above? If you haven't yet done this, please do this before responding. Turn off all 3 first, then if the noise goes away, turn on one at a time to learn which one the Forte has trouble handling. By the way, Forte is intended for piano-like sounds so it wouldn't surprise me if it has trouble handling much more than one continuous stream of pitch Bend.

[PHY6]

It's deffinately a ground loop problem.
I've had this behaviour with a synth once. All I had to do is change the synth to another power outlet.

Is your Linnstrument powered by the computer usb ? Maybe try with a power suply on another outlet.
And offcourse try another midi cable, if you didn't allready.

Good luck !

[ceasless]

I hear the buzzing sound when you play in the recording. Questions:

* The noise occurs in the phones output of the Kurzweil, so it must be coming from the Kurzweil and nowhere else. If this is a recording of the Forte's output, why is the Forte producing no instrument sound when you play?

I have the LS pointed to a channel where I've put a VAST program that has no sound source.

Otherwise the speakers would have blown at the gain setting I was running.

* You mentioned that all works fine when routed over USB, so I assume you are connecting LinnStrument directly to the Forte using a MIDI cable. I assume also that when you connect via USB, you are connecting LinnStrument via USB to computer, then computer's MIDI interface to Forte's MIDI In jack. Is this correct?

The LS and the Kurzweil are communicating both over USB MIDI connections routed through various hosts on the computer. Both connections go straight to the computer.

* What happened when you turned off LinnStrument's sending of continuous X, Y and Z data as described in the FAQ I gave you above? If you haven't yet done this, please do this before responding. Turn off all 3 first, then if the noise goes away, turn on one at a time to learn which one the Forte has trouble handling.

I'll be damned. Each of them introduces additional "clicks" into the audio at more or less the same amount (depending on what I'm doing with my fingers, of course).

Sorry I didn't do that earlier, Roger.

However, even with all axes disabled I still hear a single click. So it doesn't disappear entirely when the X, Y, and Z data are disabled. I tested with an MPC (oh, thanks also for that one too man! ) and the messages are clicking there as well.

I'll let you know what Kurzweil support says.

I'll continue to investigate how it is responding over USB. I never heard any issues and the continuous data didn't seem to be an issue...

By the way, Forte is intended for piano-like sounds so it wouldn't surprise me if it has trouble handling much more than one continuous stream of pitch Bend.

While it may have been released and marketed as a stage piano, it was always a VAST synth under the hood. In that sense it cannot really be said to have been "designed" in any specific way for playing the piano. That design/tuning happened at the program level and in broader gestures of the hardware and OS design.

Previously the editing was only available from software, but recent OS releases have opened VAST editing directly from the front panel. The screen makes VAST editing quite enjoyable and was a major factor in why I got it.

I took a look at some of the options and VAST seemed like a natural fit for the LinnStrument and expressive controllers in general due to the complexity of processing you can do to the inputs via FUNs.

Obviously I will have to re-evaluate this.

(As a trivia, somewhere on the internet there's a link to a customs slip for a Kurzweil shipment to NAMM some years ago citing "K3000 Stage Pianos". From what it looks like to me, they had the hardware and the sounds ready for a real upgrade to the K series, but the software was a number of years away from being ready. So they delivered a stage piano but have been upgrading it steadily.)

[Roger_Linn]

Thank you tracing down the problem. It could be due to crosstalk between the digital and analog signals inside the Forte, or a ground loop between all of your connected devices. It is not a problem with MIDI overload in the Forte because it occurs with only Note On and Note Off meassages, though MIDI overload may also occur with normal MIDI message volume.

What did you mean by the following?:

"it responds properly and without noise when routed over USB without any adjustments necessary"

Also, do you hear the noise during normal play of the Forte? If you only hear it by setting the Forte to an empty preset and turning the volume up very high, you may be casting a spotlight on something that is not really a problem.

[ceasless]

Thank you tracing down the problem. It could be due to crosstalk between the digital and analog signals inside the Forte, or a ground loop between all of your connected devices. It is not a problem with MIDI overload in the Forte because it occurs with only Note On and Note Off meassages, though MIDI overload may also occur with normal MIDI message volume.

While I cannot rule out grounding, I've taken just about every step I can to mitigate this. The Kurzweil and the audio interface are plugged into two different zones on my power conditioner.

I'll give a test from a different outlet at some point. I've also reached out to Kurzweil support.

Thanks for your help, by the way.

What did you mean by the following?:

"it responds properly and without noise when routed over USB without any adjustments necessary"

I mean that channel per note mode works fine with all three dimensions and I do not hear any distortion. I just spent the afternoon crafting a Linnstrument specific patch and testing this further. This issue with clicking aside (I've been using USB MIDI today), it is behaving as awesome as I expected it to. I can't wait to share some demos with the community.

Also, do you hear the noise during normal play of the Forte? If you only hear it by setting the Forte to an empty preset and turning the volume up very high, you may be casting a spotlight on something that is not really a problem.

I noticed this while playing expressively

Take CC#11. When things are quiet, the buzzing sticks out. Then even when things get louder I can still hear it because it is sticking out to me.

In other words, it is audible in normal patches as well. The keymap I created to debug the issue was only to be able to prove its existence beyond the shadow of a doubt.

[BobDog]

If you remove the usb cables from both the Forte and the Linnstrument and use direct midi cables does the problem go away?

[Roger_Linn]

Sounds good. Please let us know what Kurzweil says.

Regarding power, it's best for all devices to be powered from the same power strip. I don't know what your power conditioner's zones are, but the goal is to have the grounds of all devices connected as close together as you can.

And thanks for your thanks. You are very welcome and I look forward to any videos you are willing to share.

[ceasless]

Sounds good. Please let us know what Kurzweil says.

Regarding power, it's best for all devices to be powered from the same power strip. I don't know what your power conditioner's zones are, but the goal is to have the grounds of all devices connected as close together as you can.

Power is one of those things I have researched where I feel helpless to ever make real heads or tails of it all.

FWIW, I'm referring to the "isolated banks" referred to at the Furman site: http://www.furmansound.com/product.php?div=03&id=PL-8CE

Both banks should be connected to the same ground, though, I suppose. I mean, there is only one plug out of the back.

Speaking of power and confusion, even Furman gear is apparently quite controversial to some people. They claim it is nothing but a power strip that has been racked. Then there are reviews from gigging musicians who call it a game changer mentioning how they wish they had had it at the gig where their gear blew up.

I'll try plugging them into the same bank as well as trying with the computer plugged into the Furman as well.

And thanks for your thanks. You are very welcome and I look forward to any videos you are willing to share.

My idea was to launch it with a two-part Forte/LinnStrument review. Still have a fair bit of leveling up to do first, but I'll get there!

@PHY6 and @BobDog -- thanks for jumping in!

I've been meaning to get a dedicated power supply for the LS. I'll let you know how it goes without the USB MIDI interconnect once I do. I might also just try it with a USB charger plug, though it feels fiddly to do so somehow. "USB charger plugs are for micro, not mini!", says an irrational corner of my brain.

[Roger_Linn]

Regarding a power supply, I'm aware of very few people who use them with LinnStrument, which is why I removed the power supply input on the LinnStrument 128. USB is the new standard power source for low-power digital devices like LinnStrument, phone and tablets, and only requires one cable to your computer. And USB power works for all of LinnStrument's power needs, regardless of whether you're using USB MIDI or DIN MIDI, computer or iDevice sound source.

[ceasless]

Regarding a power supply, I'm aware of very few people who use them with LinnStrument, which is why I removed the power supply input on the LinnStrument 128. USB is the new standard power source for low-power digital devices like LinnStrument, phone and tablets, and only requires one cable to your computer. And USB power works for all of LinnStrument's power needs, regardless of whether you're using USB MIDI or DIN MIDI, computer or iDevice sound source.

True. I guess I'm old school. When I was looking at the 128 I was a touch disappointed at the missing power port.

That said, I've had it a month and not gotten a charger for it yet, so...

But on the good side, I was playing the trumpet patch I've been working on for a while today and I didn't notice the clicks. So it might be a non-issue, as you said.

Also I can eventually pick up a USB MIDI hub. That would be the best option for serious standalone play anyway, as then the LinnStrument can run at full speed.