Nuforce STA200

Hi Mr.D.  I was hoping to hear from you.  Your comments about this amp are largely why I decided to buy a pair.  Apparently, RV used to recommend vertical biamping in his manuals, mine included.  He now recommends against it on his website and his newer manuals.  Here is a quote from RV himself on the “Ask Richard” section of his website:

”VERTICAL BI-AMPLIFING IS NOT RECOMMENDED AS MANY AMPS OSCILLATE WHEN NOT HAVING A GROUND RETURN DRIVING THE TOP END OF THE SPEAKER. THIS PART OF THE CROSS-OVER IS CAP COUPLED FOR BOTH THE MID-RANGE AND TWEETER THIS COULD CAUSE THE AMP TO OSCILLATE AT VERY HIGH FREQUENCIES. THIS COULD BE A PROBLEM AND DAMAGE THE TWEETER.”

This has me scared to try.  I wonder if this phenomenon is unique to his first order crossovers.  I have had my 2ce Sigs vertically biamped with Rotel for the past 13-14 years.  But I’m still scared of damaging something if I do the same with the STA200 I just ordered.  Thanks!

RV would certainly know best...give the company a call about your specific system

The NF STA 200 has a much wider bandwidth than the Rotels. What this means, I am not really sure, technically, because musically, the high frequencies on the NF are musically capable of reproducing much higher frequencies, with music signals. I still do not know what he has done differently, than 10 years ago. There must have been some folks ( likely just a handfull ), who had some issues, as it only takes one issue to raise a white flag. Same happened many years ago with a particular speaker wire, by Polk, that caused some amps to oscillate. I had these cables, and never experienced an issue. I know the STA 200 does not do well below 4 ohms, but this oscillation thing is completely different. If it were me, I would try it, as I have had very good luck, without things oscillating during my many audio years. But, this is me..........you can always replace tweeters, lol.....Seriously, I feel the STA200, based on all of the circuit research I did, would not go into oscillatio; The Vandys, as much experience I have had with them, never caused a problem to any amp I am aware of, except for a clipping issue, which is different than oscillation. It is your call. Could create a new purchase of a pair of tweeters. The Nuforce will likely be better, in sq, than the older Rotels. Like I said, if it were me......You, are not me....Enjoy ! MrD.

Thanks JL35 and Mr.D.  I think I’ll see if RV knows about the NF amp.  I might even ask, in a diplomatic way, whether his retraction was an overreaction to a minute number of incidents.  Thanks again!

I wanted to report back that I have now tried a pair of the STA200s vertically bi-amping my Vandersteen’s.  No oscillating!  Phew!  The amps sound great, but they’re still breaking in.