I just did a clean install of Platinum.  But I was testing Superior Drummer 3, and there's crackling when it plays.  I went to Audio/MIDI setup within Toontrack, and it has ...
Device Type:  ASIO
Audio Device: Focusrite  (my interface)
But it has the source as Audio rather than MIDI.   I guess I thought since it's Toontrack, it should be MIDI.
 
I need to fix the crackling.  What do you suggest?
 
Thanks!
Greg

Hi. Try upping the MIDI playback buffer to 500 ms, in Preferences.
IIRC ,it defaults to 250.
All the best.

No VST instruments are audio output. MIDI triggers the sounds. 
Crackling audio is usually an indication of a problem with the audio driver. 
 
Have you run Latency Monitor? 
Optimized your system?
Up to date drivers for the interface?
Wireless internet OFF?
Buffers set in the middle or Normal ( 256) 

Focusrite have released new drivers (dated 11th January 2018) for their Scarlett range.  Might be worth an install to see if the resolves your issue.  You might also need to increase your audio buffer size.  Mine is set to 256 samples and I have have no issues.

Note: this is for 2nd generation, but it looks like 1st generation uses the same driver.  To be absolutely sure, select the right generation from the drop down.

https://global.focusrite.com/downloads?product=Scarlett+2i4

Thanks, guys, for your input.  I did install the Focusrite drivers about 2 weeks ago.  
 
But I'll look into your other suggestions and check back in.
 
Thanks!
Greg

greg54
Thanks, guys, for your input.  I did install the Focusrite drivers about 2 weeks ago.  
 
But I'll look into your other suggestions and check back in.
 
Thanks!
Greg

The driver promidi is referring to was release 3 days ago.

Also worth trying a different USB2 port.

I checked the Focusrite driver and it was the newer one - 4. something, I think.  Ever since I installed it, I've been having minor issues.  After doing a clean install this morning, it began crackling.  On my Focusrite products page it only has the newer driver.
 
But I had downloaded the old one onto a flash drive a couple of years ago.  I installed that, and now everything is fine.  But I did increase the buffer size to 500ms.
 
Thanks for everyone's input and help!  I really appreciate it!
Greg

OK, I thought this was done with, but I'm still having issues with audio.   I don't get crackling anymore.  But when I hit "play," sometimes it pops.   Not all the time, but sometimes.   What causes it to do that?  Is that still a driver issue?
 
Thanks!
Greg

What sample rate are you using?