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So I got this AVR a few days ago to pair with the 683's and I have to admit I LOVE the sound. I assigned the back two channels to bi-amp the speakers. Everything is great, but when I bring it up about -10 on volume the AVR goes into auto protect. The people at NAD said this is due to the fact that my speakers are going below the ohm load that the AVR can handle (4 ohms appears to be the lowest NAD can handle) and if I want to listen at that volume I should get a separate 2 channel amp. I'm honestly ok with that down the line, but i just want to make sure this receiver isn't defective. Is this something that should happen with my set up? I figured for sure this AVR could handle my speakers. 
 

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I have a pair of KEF R900 powered by a NAD T777 and every once in a while mine does the same....NAD support mentioned the same to me about the receiver being 4 ohm stable and that my speakers may dip below 4 ohms at times and trigger the auto protect. I checked my speaker specs and although they are listed as 8 ohm nominal the minimum is listed as 3.7 ohms....checked the specs on your 683s and they re also 8 ohms nominal but list a minimum of 3 ohms. I was also wondering the same thing then saw your post which seems to confirm my situation as well. I had an additional issue that required a firmware update and NAD support ws great in that regard in getting me the firmware - was able to do the update myself. I do love the sound as well .
 

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hi guys i recently purchased the NAD T758 and i have B&W CM8's and had exactly the same issue, not sure about your speakers but mine are 4 pole and the NAD representatives solution was to bi amp the speakers and this worked for me and also improve performance, thought i would just make the suggestion as it may help. 
 

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Quote:
Originally Posted by benji100  /t/1521478/nad-t758-b-w-683#post_24710625


hi guys i recently purchased the NAD T758 and i have B&W CM8's and had exactly the same issue, not sure about your speakers but mine are 4 pole and the NAD representatives solution was to bi amp the speakers and this worked for me and also improve performance, thought i would just make the suggestion as it may help. 

The KEFs alaso are 4 pole speakers and can be bi-amped or bi-wired. I may try this as well as mine continues to shut down during what I think are relatively moderate listening levels. The CM8's actually have a minimum impedance listed as 3.0 ohms whereas the R900s I have are listed at 3.7 ohms (Bother are 8 ohms nominal). How often were the CM8's causing the T777 to shut down?
 

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I know this is an old thread but i m considering buying a Nad T758 for my B&W s600 speakers, has this problem been solved? or the avr still goes to auto protect at high volume?


Thanks.
 

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I know this is an old thread but i m considering buying a Nad T758 for my B&W s600 speakers, has this problem been solved? or the avr still goes to auto protect at high volume?


Thanks.
The way to solve it is to buy a power amp that is 2-ohm stable, or at least "known to be stable at 3 ohms" (amps are very rarely rated to 3-ohms and usually have a rating that is a power of 2) or to not listen loud enough for it to attempt to draw too much current from the T758

While I don't have those speakers to verify, I would also say if the NAD can't handle it, I doubt many other receivers would, either, but this is not an absolute statement by any means. Maybe an Anthem receiver could do it? I don't know.

But you can't increase current handling with firmware, and there is no way to increase the resistance of a speaker short of redesigning it or putting a wasteful and inefficient series resistor in series with it.
 

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I know this is an old thread but i m considering buying a Nad T758 for my B&W s600 speakers, has this problem been solved? or the avr still goes to auto protect at high volume?


Thanks.
Hi blackspider, I still have my 758 and have had further issues thanks to Nad but that was a different issue altogether (4k) my solution for the high volume shut off was to bi-wire the front speakers which is fine if your only using 5.1 as I do.

Hope this helps. I'd look for something else though i'm not super impressed with Nad, look at Rotel
 

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Hi blackspider, I still have my 758 and have had further issues thanks to Nad but that was a different issue altogether (4k) my solution for the high volume shut off was to bi-wire the front speakers which is fine if your only using 5.1 as I do.

Hope this helps. I'd look for something else though i'm not super impressed with Nad, look at Rotel
hmmn, i will be using it with dolby atmos setup 5.2.1, so no bi-amp for me. Guess i m screwed then?

i got the s684 s2, dunno if those will give an issue as well. At what volumes did it trigger your NAD to shutdown & go to auto protect?


Thanks.
 

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Seriously not that loud which is why I was not impressed, it was getting up to almost as loud as you would want to go but not to the point where your ears bleed! I mean previous to the Nad i had a £500 once which ran them better and because it was pre digital amps and protection circuits it never cut out just got warm, but you would never listen to it at that volume for long periods just occasionally if your like me i listen to my music in 2 channel and sometimes wanna listen loud.

The Nad went back to sevenoaks and they tested it on their cm8's and the same happened and one thing that really annoyed me was Nad's customer service basically there isn't any, they just tell you to take it back to your retailer. I spoke to b&w about it and they were fantastic i spoke with a guy for around an hour and a half on the phone and we went thru testing my speaker impedances etc to check they are what they should be and as I'm an electrician i had the knowhow to do this, i mean b&w wouldn't comment on the and as its not their product etc but they were far more helpful than nad. He also mentioned most of their speakers run at low impedances under 4 ohms so perhaps the 684's would be the same.

If you want my advice don't touch Nad with a barge pole! Ive tried to sell mine 3 or 4 times and can't shift it so I'm stuck with it and I'm not prepared to just go and spend 1500-2k on replacing it and lose a grand that it cost me.

If i were buying now i would seriously consider the Cambridge CXR these are powerful and clean, after that your into big money like a hotel or anthem or naim.
 
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