Taming the Yamaha THR10 Whine(s)

The THR10 is a nice practice amp and even for recording.  I've used mine with Lead Guitar, Bass and Rhythm Guitar. 
 
However, it has two separate whine/noise problems.  The first one is a high pitched whine and is a routing problem with a wire and detailed (and fixed) in this thread: Yamaha THR10 Squealing Noise Fix | Pick Roar

The "pickroar.com" fix, fixes the whine when on battery mode. I was getting the whine through my Roland Studio-Capture and could easily hear it on my studio monitor speakers. Moving and securing the wire as shown in the "pickroar.com" fix took care of that problem.

However, when using the AC power adapter (it is a switching power supply and puts out 15VDC) I had a louder "whine" and noise. After testing, I found placing a D.I. box between the output of the THR10 (Headphone out - the only output jack) and the recording interface unit (Roland Studio-Capture) and lifting the ground removed the AC power whine and noise. It is not a ground loop hum but more a higher frequency somewhere above 1Khz (I didn't measure it).   I also tried my Ebtech hum eliminator and although it is NOT a ground loop problem, the Ebtech also fixes the problem.

For those that are using this unit, keep these fixes in mind if you encounter the same problems.

The high pitched whine problem has a lot of hits if you google it.  The fix from the pickroar.com site is the fix referenced on several different sites.
 
 

Yes, thanks firebird for posting this. I have a THR10c and thankfully I have not had this issue, but if I do I have bookmarked the link you provided. It seems to be a fairly straight forward fix.
 
Cheers,
 
Billy Buck