Nuforce STA200

Thanks randy, I am hoping someone owns/has owned the little amp and could share their experience, but does not seem very popular.

Thanks jl35, that is good to know.  If you don't mind give your thoughts after break in is complete.

Thanks again jl35 and aberyclark for providing your listening experiences.  

mrdecibel, I purchased a STA200 about a month ago when Audio Advisor received them back in inventory again.  As was discussed previously, the amps high gain resulted in me only being able to turn up the volume on my tube preamp about 1/3 of usual.  At someone's recommendation, I purchased the Schitt Sys passive for less than $60 including shipping and put it between my pre out and amp, and that did the trick perfectly.  I have had only tube amps for a long time, but I am enjoying the STA200 quite a lot.  At $499 I am quite happy.

mrdecibel, what is the item that is on the stock STA200 power cord just below where the cord attaches to the amp?  I assume it doesn't impact ones choice of power cord? Thanks

Thanks mrdecibel, I have seen them often, but I never knew that they were all basically the same device inside the cover, performing the same function. Live and learn.

I guess adding to the above, and I have not looked into it at all, I get the impression that the STA200 is the only non class D amp they make?

I am not concerned one way or the other, but based on the above and the link, do you believe that the Nuforce and Job are more or less similar amplifiers?

Yes, but at what point does having, as you mentioned above, different caps, resistors, power transformers and RCA jacks override the similarity in sound from having similar circuits?

Not a concern one way or the other to me, I like the amp.

Thanks, jl352.  Incidentally, I was lucky to not have the preamp/speaker mismatch. I guess the three pairs of speakers I have used the amp with were not so efficient to create any (hiss/volume control)  problems.

I did end up purchasing the simple little Schitt sys which I like experimenting with just for fun, but most of the time I have it set full volume so as to not impact my tube preamp signal going to the amp.

I have had no problem powering either my 6 ohm 89db or 6owhm 85db speakers, but neither are crazy loads.  Also, not sure if its because I have a tube preamp or not, but no obvious gain problems.  Maybe just lucky.

Before anyone askes, yes I do realize there is a large price difference.

mrdecibel or anyone else who may have heard both amps.  I noticed that Audio Advisor is blowing out their Parasound A21's due to the new model A21+.  If I purchase the A21, what and where do you believe would be the level of improvement over my STA200?  Two pairs of speakers are both 6 ohm, one pair being 85db and the other 86db.  I am using pair of SVS subs.  Volume is currently not a problem in my listening area. Thanks in advance for any input.

jl35, thank you for your response, decisions, decisions.

mesch, in layman’s terms, please explain exactly what are you being cautious about? Are you worried about the amp being driven into oscillation?  How does the fact that the amp produces the same power at 8 and 4 amps create a potential problem? If neither of these are the concern, what is the worry? Thanks in advance.

aysancorluhan,, I already have the STA200, and the truth is worrying about it blowing up is the last thing I am doing.  I have not popped the hood to look myself, but it sounds like you are saying it is not fuse protected, which seems unusual.
 
While I am not currently thinking about new hard to drive speakers, I was really wanting someone to provide their input (thank you jl35) regarding the sound quality differences between the STA200 and a Parasound A21.  For example, does one image better than the other, better separation of instruments, anything else at all you can relate.

Here's a bump to mesch, or anyone else.  We have a first time poster declaring his amp blew up, and mesch stating he will use his amp with caution.  I am not savvy enough to understand or otherwise translate from above what "the degree of attenuation becomes too low overdriving the input stage" means or how it creates a situation that can be hazardous to the amplifier.  Since it has been brought up as a potential danger, lets hear what the danger is?  There are not that many posts on A'gon where using an amplifier for its stated purpose can create a potentially dangerous situation, that perhaps an amplifier has been built without normal protections built in, since this has now been brought up, lets hear the background behind it and potential danger.  Thanks in advance.

Mesch, I have two pairs of nominal 6 ohm speakers, both probably in the 85db range.  One is a 2&1/2 way with two 7 1/2" or so scanspeak mid/woofers.  I can run the unit all day, with the STA200, being fed by this tube preamp, http://www.divertech.com/coplandcta305.html and the amp never is even warm to the touch.  I have a Schitt sys, but honestly it is set to not reduce the output to the amp at all as it is not needed.  In other words, the volume control can be turned up far enough (high enough) from the zero position with the sys in or out of the system to not worry about the preamp volume control not being high enough to function fully.  I don't understand the impedance matching thing to know if I happen to have a more compatible preamp than normal or what.

Thanks mesch for your clarification, truly appreciated.  From your earlier post I got the mistaken impression that you were saying that you knew of an identified amplifier design weakness that could result in possible serious amp failure.  I don't think this any longer.  These things do happen though, for example, I have a pair of Goertz alpha core speaker cables that without the use of zobel networks have resulted in some amps going into oscillation with not pretty results.

So blue skies on this end.

I have been on A'gon for a whole lot of years.  You will note that the poster with the blown amp has exactly one post on A'gon.  I have found throughout the years that people who post once or twice with something negative often have some beef somewhere down the line.  Not saying this is the case here about the poster, but I now think the risk of blowing an amp is pretty much the same as the risk of blowing any other amp lower powered amp.  By the way, in the old days SS amps often had much lower watts at all ohms than this unit.

Glad you happened by mrd, best to you and yours.  George

Mike, your making me laugh.  In the late 70's I answered a classified ad and purchased a used Sansui receiver and Cerwin Vega speakers, just for a back patio room. I just came to expect compliments on the sound of that low $ stereo, and never again on any other set-up, including some plus $20K systems.  I eventually gave it to a friend.

My STA200 was/is dead quiet.  I am told some systems could have a gain issue which from what I understand means that if you pair the STA200 which has a high gain with a preamp having high gain you can end up with the hiss you mention.  One fix for this is a Schitt Sys passive for $49 between the amp and preamp.  Its set once and forgotten.  Unfortunately it does not sound like you have time to work through all of this, and really may just have a "bad" amp and not an gain issue.  If I have this wrong someone please jump in and correct me.

I did not have the too high a gain preamp/amp mismatch with my tube preamp.  While we have certainly discussed this problem here and read about it, I am curious if anyone has actually experienced the gain issue and if so:

1. Did the problem create an auditory hiss? or if no hiss,
2.  Was the problem not being able to turn the volume control up high enough to adequately use the preamp's sweet spot?

Thanks in advance

Hi mesch, not to worry, you don’t come off as faulting the amp at all. The way I look at it, whatever faults it has, it doesn't owe me anything. 

Hi japol, waiting for Mr. D to chime in.  

But when you mention having a noise without any input connected.  Do you mean the noise is coming from the amp when there is no preamp or speakers connected?  If that is the case I would think it is defective and send it back and ask for a replacement.  But again, definitely wait for Mr. D.

Hi Japol, I hope Mr. D posts here quick to help you out as I don’t have enough experience with gain issues, so these are just random thoughts until the voice of experience chimes in. My first thought would be that to determine if you have a gain issue you should just hook up the Sys with the amp, and the amp to your speakers and with no sources connected see if there is a "hiss" caused by too much gain or the if there is still the "high pitched noise". If not, I would think, but may be corrected, that the noise issue is being generated by your sources, wiring or a ground loop.

If you determine that in fact these noises are the result of the amp I would not think twice of exchanging it for another one or if you choose a refund. If it was a noise floor thing I would think the "hiss" would be the same level from both speakers, and no matter what there should be no "high pitched noise". But again, wait for Mr. D.

Hi japol, if I understand your post above you have a hum with both the nuforce and with your sony integrated.  So you are not sure if you have two amps with a problem or the problem lies elsewhere in your system.  You have already determined that your speaker wires are ok. 

I only have a couple of thoughts.  One is are you using shielded interconnects and if shielded you are sure they are functioning properly?  The other is that I have the TV cable box connected to my preamp and this resulted in a hum through my speakers.  I had to purchase a cable tv ground loop isolator which eliminated it. 

You know, one person posted their amp had a problem, and that person never posted again when asked to.  Then an article came out that said the wattage at 8 and 4 ohms was the same and started some worry that this was a problem.  

I ran my amp for about 8 hours straight both days over the weekend.  My speakers are 85 db and nominal 6 ohms and the amp never got warm and has never been warm to the touch. At least with my amp there is no difference in temperature between on and off. 

Hi deseldin, really nice that you are enjoying the STA-200, it is a fun amp, and its funny that I believe it is the only AB amp they made, the rest being class D (AFAIK).  For me, without mrdecibel's input I wouldn't have purchased this inexpensive little gem.  

The SYS is a fun little toy, the first of its sort I have had.  Have fun.

Busy now, but agree it will be fun to use the little SYS as a standalone pre in the near future to gain that experience.  Thanks for the thought MrD.

mrD, your post made me laugh. Why would you want to add more weight to the SYS unit? According to the Schitt website it already weighs in at a heavy 1 lb. I’m guessing they rounded up to get there.