Bush thug Posted May 19, 2021 Share Posted May 19, 2021 I have changed speakers from focal 826w 30th anniversary to sonus faber cremona m and I had it pretty loud but no louder then I have had the focals but the amps switched off and where really ridiculously hot. glad after about 2 minutes they powered back on and started working again. is there different rules with 4 ohm speakers. the amps are abrahamsen v4.0 up and are bridged so I have 2 mono blocks. I have never had this problem before. is it best to unbridge them. thanks steve Link to comment Share on other sites More sharing options...
Fangzie Posted May 19, 2021 Share Posted May 19, 2021 I think you may be right and unbridging them might prove necessary. The Sonus Faber shouldn't be a terribly difficult load per se, but are a 4 ohm speaker and my understanding is that bridging amps can make driving lower impedances more difficult, noting in particular that your amps do not provide a rating below 4 ohms, at least at a quick glance at the manufacturer's website. Link to comment Share on other sites More sharing options...
andyr Posted May 19, 2021 Share Posted May 19, 2021 What the man said ^ ^ ^, @Bush thug. Bridged amps and 4 ohm spkrs don't play together well. But the specs on your amp (that I could find) said: "2 x 70 watt into 8 ohm | 2 x 140 watt into 4 ohm" - so in its normal stereo state ... I would think it should handle your SF Cremona well. Andy Link to comment Share on other sites More sharing options...
Bush thug Posted May 20, 2021 Author Share Posted May 20, 2021 awesome thanks. that was my thoughts Link to comment Share on other sites More sharing options...
Bush thug Posted May 20, 2021 Author Share Posted May 20, 2021 just another quick question please cause 4 ohm is new to me on the sonus faber cremona m they say they are a 50 to 250 w rating. is that a rating in 4 ohms so I would take the 4ohm rating from my abrahamsen it would be giving them 140w of power instead of the 70. is that correct Link to comment Share on other sites More sharing options...
andyr Posted May 20, 2021 Share Posted May 20, 2021 Just now, Bush thug said: I would take the 4ohm rating from my abrahamsen - it would be giving them 140w of power instead of the 70. is that correct Correct! 1 minute ago, Bush thug said: just another quick question please cause 4 ohm is new to me on the sonus faber cremona m they say they are a 50 to 250 w rating. is that a rating in 4 ohms Spkr mfrs generally design their specifications to confuse ... rather than enlighten. So I can't answer that for you! Possibly others will be able to give you a definitive answer? Andy Link to comment Share on other sites More sharing options...
Steever Posted May 20, 2021 Share Posted May 20, 2021 (edited) I was lead to believe a stereo amp bridged into a 4 Ohm load actually behaves as if it's driving a 2 Ohm load. I recently had to run one of my car audio amps in stereo (thus less power) into a two Ohm load so it wouldn't overheat. Sure it was less power but I didn't have heat and shut down problems. I ended up changing my amp to better suit the load so no problems now. Edited May 20, 2021 by Winno 1 Link to comment Share on other sites More sharing options...
rantan Posted May 20, 2021 Share Posted May 20, 2021 1 minute ago, Winno said: I was lead to believe a stereo amp bridged into a 4 Ohm load actually behaves as if it's driving a 2 Ohm load. This is correct . Bridging always tends to create more problems than it solves ( if any ) The improvements it brings are really the wrong ones in that WPC is increased,but this is far less important than high current capability into lower impedances. 1 Link to comment Share on other sites More sharing options...
Grimmie Posted May 20, 2021 Share Posted May 20, 2021 Perhapsthis would give you the opportunity, once un-bridged and back to 2 X stereo, to bi-amp your Sonus fabers. I presume this is possible with them. Saves wasting a couple of chanels too. Link to comment Share on other sites More sharing options...
Bush thug Posted May 20, 2021 Author Share Posted May 20, 2021 took the amps out of bridged mode it actually sounds much better bass is alot bigger and tighter and I don't think I have lost any volume at all. thanks everyone for your help much appreciated 9 minutes ago, Grimmie said: Perhapsthis would give you the opportunity, once un-bridged and back to 2 X stereo, to bi-amp your Sonus fabers. I presume this is possible with them. Saves wasting a couple of chanels too. no bi amp option unfortunately 1 Link to comment Share on other sites More sharing options...
Bush thug Posted May 20, 2021 Author Share Posted May 20, 2021 Any benefit in using just one channel on each amp Link to comment Share on other sites More sharing options...
RoHo Posted May 20, 2021 Share Posted May 20, 2021 1 hour ago, Bush thug said: just another quick question please cause 4 ohm is new to me on the sonus faber cremona m they say they are a 50 to 250 w rating. is that a rating in 4 ohms so I would take the 4ohm rating from my abrahamsen it would be giving them 140w of power instead of the 70. is that correct These power ratings are bordering on meaningless and IMO are mainly used as a disclaimer by speaker manufacturesrs. I interpret the above rating to mean "The speakers will definitely play loud enough on a 50W amp and won't blow up on a 250W amp." Which is not to say that a) you may be perfectly happy running them on a 20W amp or b) you may use a 1000W amp with care and the speakers will be fine 2 Link to comment Share on other sites More sharing options...
andyr Posted May 20, 2021 Share Posted May 20, 2021 8 minutes ago, Bush thug said: Any benefit in using just one channel on each amp Maybe! It depends if the 2 amplifier channels in a stereo amp share the one power supply ... or whether they have one each. If the latter - then there is no benefit in just having 1 channel connected to the spkr. If the former - then with the PS dedicated to just the demands of one channel ... the two amps will sound better than when the PS of just one amp is powering 2 channels. (A pair of Naim 135 monoblocs always sounded better than a (stereo) 250.) Andy 1 Link to comment Share on other sites More sharing options...
Bush thug Posted May 20, 2021 Author Share Posted May 20, 2021 alright so have changed everything thing now in different stages through out the day with small listening sessions of around and hour in between volume always the same. I am not sure if I am just imagining it pretty sure I am not but my report is switching back to a single stereo amp out of bridging playing stereo I noticed a huge improvement in bass response deeper and cleaner. then switching back to 2 amps only using one channel not bridged the soundstage grew quite a bit and gave more clean headroom. its an improvement on the bridged amps for sure. these are beautiful speakers and so glad I took a chance with out hearing sonus faber before. Again thanks again for your help cheers steve 1 Link to comment Share on other sites More sharing options...
andyr Posted May 20, 2021 Share Posted May 20, 2021 21 minutes ago, Bush thug said: alright so have changed everything thing now in different stages through out the day with small listening sessions of around and hour in between volume always the same. I am not sure if I am just imagining it pretty sure I am not but my report is switching back to a single stereo amp out of bridging playing stereo I noticed a huge improvement in bass response deeper and cleaner. then switching back to 2 amps only using one channel not bridged the soundstage grew quite a bit and gave more clean headroom. its an improvement on the bridged amps for sure. these are beautiful speakers and so glad I took a chance with out hearing sonus faber before. Again thanks again for your help cheers steve Interesting, Steve - this confirms what 'folk lore' said about a pair of Naim 135s vs. a 250. So it would seem your Abrahamsen amp is built with one PS shared by two channels? Andy Link to comment Share on other sites More sharing options...
Bush thug Posted May 20, 2021 Author Share Posted May 20, 2021 (edited) 15 minutes ago, andyr said: Interesting, Steve - this confirms what 'folk lore' said about a pair of Naim 135s vs. a 250. So it would seem your Abrahamsen amp is built with one PS shared by two channels? Andy yeah only one power supply for 2 channel Edited May 20, 2021 by Bush thug Link to comment Share on other sites More sharing options...
Dean Gale Posted May 20, 2021 Share Posted May 20, 2021 Don't get caught up on rating this or that other than Speakers rated at 4 ohm should not be used with amps in bridged mode . It says it plainly on the back of most amps use 8 ohm speakers or more in bridged mode. If the manufacturer says that there is a reason , it will overheat the amp eventually causing it to fail. If you run a 100 watts through your speakers continuously you will go deaf just before the speaker coils burn out as well. 1 Link to comment Share on other sites More sharing options...
Deepthought Posted May 26, 2021 Share Posted May 26, 2021 The actual impedance of the Sonus Fabers is very low and has a nasty electrical phase shift too: However, that amplifier must still be capable of delivering a goodly amount of current. Even though the Sonus Faber's impedance magnitude remains reasonably uniform at higher frequencies, it drops to 2.8 ohms through the upper bass, with a cruel combination of 4.5 ohms and a -53 degrees electrical phase angle evident at 73Hz (fig.1)."" https://www.stereophile.com/content/sonus-faber-cremona-loudspeaker-measurements I can see why your bridged amps are running hot 1 Link to comment Share on other sites More sharing options...
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