Humming when run over MIDI

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Surprisingly, DIN MIDI is very fast and you'll probably never notice any slowness, even with MPE chords. I think people think it's slow largely because manufacturers have been very successful at blaming MIDI for the slow software or processing speeds in their products. But they don't have Geert. :)

I'm not aware of any USB hubs that are optimized for MIDI, only USB hubs. Note that many USB hubs internally slow down the USB data or limit the power to each USB port, so I'd recommend not using them unless you need more physical ports, and then I'd put other peripherals on the hub and connect LinnStrument direct to the computer.

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I was thinking of something like this: http://www.iconnectivity.com/products/midi/mio4

"USB Host Port supports a USB MIDI Class-Compliant device (add your powered USB hub and connect up to eight devices)"

I wouldn't consider the DIN MIDI response to be lacking. I would be adopting something like that specifically to avoid the clicks.

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That's a MIDI interface, not a USB hub. A USB hub is a device that provides multiple USB A ports (flat rectangular jack) for peripherals from a single USB B port (square jack) connected to a computer. It is used if you have need of more USB ports than your computer has.

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Roger_Linn wrote:That's a MIDI interface, not a USB hub. A USB hub is a device that provides multiple USB A ports (flat rectangular jack) for peripherals from a single USB B port (square jack) connected to a computer. It is used if you have need of more USB ports than your computer has.
When I said a "USB MIDI hub", I was talking about a device which can route USB MIDI to USB MIDI, as the iConnectivity gear does.

Since USB hubs cannot route MIDI to one another without a computer, I assumed that was obvious 8)

In retrospect the word "hub" caused confusion.

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Well, I don't know if it was putting the plugs into the same banks, connecting the computer to the Furman as well, or a change in my favor in the grand cosmic radiation, but after some more extended testing over the last 24 hours I haven't noticed it in normal play.

So I'm going to consider this "fixed" for now until I hear otherwise from Kurzweil support.

Thank you everyone for your suggestions and support and especially to Roger for his patience and thoroughness.

Now, back to this trumpet patch!

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Perhaps it's voodoo. :) I'm glad it's solved and you can get back to making music!

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So, it turns out that I'm not crazy. In fact, I've turned up a bug in the Forte that made its way undiscovered all the way until now.

From Kurzweil operational support:
While I cannot comment on future product plans I can confirm that there is an audible noise (all be it very low level) induced when triggering the Forte via MIDI DIN IN. This appears to be due to the proximity of certain internal components to the A out DACs (predominantly the right channel) post the MIDI port optoisolator. This went unnoticed by all (up till now, thanks for the report) largely due to the low level and how much gain is thus required to make this audible to a noticeable degree.

So the good news is your unit is physically fine/normal. The downside is this is normal - but hopefully low enough level that it does not impede typical work conditions. The alternatives (which I think you too found) are to either use the USB MIDI functionality instead (if possible) and/or route the audio to the B outs which do not appear effected (the Global mirroring mode for Out Pair B makes this a one switch fix - manual ref. pg 12-5).
I can confirm that the issue is not present on the "B" outs.

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Aha-- that makes sense. That's what I meant when I wrote "It could be due to crosstalk between the digital and analog signals inside the Forte". Good for Kurzweil support for actually tracing down the source of the problem and humbly admitting the truth, which is rare. I suspect the reason it hasn't been noticed is that few Forte users stretch it beyond its main use as a stage keyboard. You may the first to use it for continuous MIDI control beyond pitch bend. It's the continuous pressure control of note volume that often exposes the warts because you hear what happens between silence and whispers.

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ceasless, did you know that you can comfortably power Linnstrument from "Storage" USB connector of Forte with USB cable? I've realized the same some months ago with my PC3K. That and direct MIDI DIN connection to Kurzweil should rule out any buzz. I was experiencing similar sound issues when routing MIDI via USB from LS through iConnectMIDI4 through another MIDI patchbay to Kurz. I never sorted it out but direct MIDI DIN connection solved it for me. I'm now also using digital output of PC3K which is perhaps helping with the audio clarity too, being routed to RME UCX.
In my experience USB MIDI is more prone to ground loops as it is not opto-coupled as MIDI DIN is, especially when routing gets complicated. Had similar problem with OP-1 which is USB MIDI only.
Some people report success with USB isolator cables.

I'm looking forward to your experience with VAST. I was neglecting Kurz in last months but you are right that it's total power-horse when it comes to flexibility of modulation mappings etc. Ideal partner for LS.

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Hi 48cube,
Note Kurzweil's admission that the problem is due to crosstalk between the digital and analog signals inside the Forte, not ground loops. In other words, when Kurzweil laid out the circuit board, they placed the digital USB traces too close to the analog traces, causing a small amount of radio frequency leakage of the digital signals into the analog traces.

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48cube wrote:ceasless, did you know that you can comfortably power Linnstrument from "Storage" USB connector of Forte with USB cable? I've realized the same some months ago with my PC3K. That and direct MIDI DIN connection to Kurzweil should rule out any buzz. I was experiencing similar sound issues when routing MIDI via USB from LS through iConnectMIDI4 through another MIDI patchbay to Kurz. I never sorted it out but direct MIDI DIN connection solved it for me. I'm now also using digital output of PC3K which is perhaps helping with the audio clarity too, being routed to RME UCX.
In my experience USB MIDI is more prone to ground loops as it is not opto-coupled as MIDI DIN is, especially when routing gets complicated. Had similar problem with OP-1 which is USB MIDI only.
Some people report success with USB isolator cables.

I'm looking forward to your experience with VAST. I was neglecting Kurz in last months but you are right that it's total power-horse when it comes to flexibility of modulation mappings etc. Ideal partner for LS.
Hey 48cube,

That's a great trick with the storage connector! In fact I suggested they figure out a way to turn it into a USB MIDI host port, but I somehow failed to realize that it's already transmitting power.

Fortunately it is not a ground loop issue in this case. Considering what I paid for this Furman, I'd be royal. It's solvable on board by using the B outs. If it had digital outs those would be fine as well.

I'll be sharing what I've learned so far eventually here when its polished. However if you would like to watch it unfold in more detail you should check out the Mastering V.A.S.T forums.
Roger_Linn wrote:Hi 48cube,
Note Kurzweil's admission that the problem is due to crosstalk between the digital and analog signals inside the Forte, not ground loops. In other words, when Kurzweil laid out the circuit board, they placed the digital USB traces too close to the analog traces, causing a small amount of radio frequency leakage of the digital signals into the analog traces.
Ah, is that what they meant by "the proximity of certain internal components" ? I just assumed it was a small botch strictly between output A and the MIDI In optoisolator.

But it makes sense that it would actually be a digital line messing with the analog lines, including what I am assuming are MIDI DIN ports with properly functioning optoisolation.

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On the kurzweil Forte 88 key unit when I use trs balanced cables,I get fluttering noises when I use the alpha dial, use the sliders,press global button then more > then tools then more>
and last either state or voices either one will flutter until I get until I press another button other than those 2,also when I press other buttons,a thump noise is made . Also a transformer like hum noise is continually happening. I have used a Roland kc500 and Roland kc 220 keyboard amps,a Leem pro104 stereo pa head we 2 community 15" 2 way speakers. When I used unbalanced cables, there are no noises. Weiser sound and kurzweil american music and sound and kurzweils Jean Bellafe, they all say,they have never heard of this before. Weiser sound said there should be less noise when using balanced cables. My other keyboards have no problems at all when using balanced or unbalanced cables. No one can tell me what is wrong. This is my 3rd unit with similar problems. What do you think the problem is ? I even changed outputs rooms . All outlets in the home are grounded.

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