As both a nearly 2 year old Tyros owner & former PSR2000 owner myself, I've NEVER experienced 'out of norm' VH distortion problems with 'my' Tyros. In fact, in a side by side comparison with the PSR2000,the Tyros harmonizer was dramatically improved (clearer more distinct harmonies).

Mike, Chony, Frankieve: I suspect one of two reasons for this possibly occuring on your Tyros keyboards.

1) Microphone (brand/model) used:
My experience has shown that a mic which includes a very high (HOT) output) signal is most critical when used with a keyboard built-in VH harmonizer unit. The hotter signal going into the board the less you need to boost the signal with the mic trim knob (back of the keyboard) or mic volume knob (on top of the keyboard). My question is at what level do you have the 'mic trim' and 'mic volume' knobs set at? Both of mine hover at around (more or less) the 1:30 position.

I've tested several mics with my Tyros and found that Electro-Voice brand mics provide the highest signal output, and deliver the best VH results (without distortion or harmony dropout). I recommend the model ND767a: http://www.electrovoice.com/Electrovoice/products.nsf/allpages/937B84C17B940EBE 86256B96005D42AD

2) VH Harmonizer (defective part)
If the mic knob settings or low mic signal output is not the issue, then, if you have updated to the latest Tyros OS 1.40, I would suspect it to be a Vocal Harmonizer HARDWARE problem, and perhaps a bad production run that may have included a batch of faulty parts.

I recommend that each of you email Steve Deming at ycasupport@yamaha.com and OFFICIALLY report the problem, as:

"that's the ONLY way" you have a chance of getting your Tyros VH problem fixed.

Yamaha will then assign you a case number. Keep track of that number. The more cases of this problem Yamaha receives the sooner they will act. I know because I've gone thru this song and dance routine.

I admit I had to hop, skip and jump thru at least a few hoops and wait (a LONG time (months) ) but Yamaha did finally come thru, acknowledged & corrected the Tyros USB hardware connection problem I was having (and thankfully with Yamaha covering all expenses (including shipping) as well . If the problem indeed is a wide spread (faulty) hardware problem, I'm pretty sure Yamaha will cover it under warranty, even if your specific unit is past the warranty period. At least that was the case with the USB hardware problem I encountered.

Good luck and please keep us informed.

Scott