When I play my keyboard thru platinum I get this hollow'y' sound like it's playing back thru my midi rack synth twice at the sane time.
Sounds ugly.
Anyone know what's going on? And I'm sure it's taxing on cpusage.
Thanks for any insight, and I apologize if I'm sticking this where it don't belong
Joni

What type of Keyboard do you have?  Is it an actual hardware synth capable of generating its own sounds with it's audio routed back to Sonar somehow.  If so, do you have LOCAL ON enabled on that synth?

How is your Keyboard actually connected to Sonar. Is it driving a softsynth.  Are there any effects on the track containing the synth sound.  Maybe turn off effects to make sure no effects are actually affecting the sound.

Turn off input echo

I use a controller. The controller is hooked to a motu midi express XT usb. This feeds both the daw via USB and my rack synth via midi. The rack synth's sounds go into a motu 828mk3 hybrid via toslink.
So, either the toslink signal is making a double round trip or the midi is.
I'm also getting hanging notes, which I know is a midi issue. I had this problem before and fixed it, but now it's popped up again since I just added the 828mk3 hybrid.
(No effects are being used)

And I did turn off echo

Thanks for your input

My guess is the issue will be in the Motu. The midi is leaving your DAW, into the Motu, out to the sound module returning to the Motu and being looped back again. Get out your Motu owners manual! 
 
If you unplug that TOS link cable from the module what happens? 

Sound like you have the external synth mod and the Sonar soft synth both playing when you hit a note.The doubling is the latency of the soft synth. :)
 

-to 11DREAMS~ I have no soft synth up and running. Only the hardware xv5080.

-to CACTUS~ 1, if I unplug the toslink I'm not gonna hear the synth at all in the motu 828.
Also the 828 toslink outs aren't connected to anything and are muted in the settings so I don't think the toslink audio is being re-fed back into the daw...but that sounds like what would cause this to happen. But due to the settings, there's no way it can.
I have echo turned off, but I still feel it has something to do with a midi signal being looped.
But then again, I don't have a midi connection to the 828. All the midi runs from the motu midi express XT USB to the synth module. Ugh...but even then, I have no connections going from the midi outs of the module.
I've only had the 828 a few days and I know there's a lot to learn about it, as this isn't the only issue I'm having.

Headphones into the xv5080 will tell you whether the doubling is done in the xv5080. If so, it is receiving doubled MIDI. If not, the audio is being doubled with a bit of time shift somewhere else.
 
There are a few ways doubled MIDI could happen. Most likely this: you've suggested the motu midi express XT is routing your controller's MIDI to both your xv5080 and your DAW. Then the DAW could also be sending it to the xv5080. Another possibility might be some other routing anomaly in the motu midi express XT. Yet another possibility is multiple tracks in the DAW echoing identical MIDI. Also, do you have any MIDI thru ports connected to the XT?
 
It is actually most conventional to make the keyboard not drive the synth directly (in the studio, that is; live might be different). Of course you want the DAW's MIDI to drive the xv5080. For keyboard synths, the way to accomplish this is "local off". In your case, the way to do it is not use the midi express to route keyboard MIDI to rack synth directly, but let it go through the DAW. 

Bvideo, you hit it.
Of course!
You got me thinking and 'eureka' I think you got it.
I can totally see that.
Simple. Don't make the virtual connection to the 5080 in the midi xt.

Thank you so much, and thank you to everyone who chimed in.

1 down, 99 to go..

Thank you, bvideo,
Joni

HARDDRlVER
When I play my keyboard thru platinum I get this hollow'y' sound like it's playing back thru my midi rack synth twice at the sane time.
Sounds ugly.
Anyone know what's going on? And I'm sure it's taxing on cpusage.
Thanks for any insight, and I apologize if I'm sticking this where it don't belong
Joni

Turn off LOCAL on your keyboard