NAD C275BEE in bridge mode and speaker impedance

[Sabaselfsit]

Got 2 of these lovely power amps that I run in bridge mode. In the user manual they recommend=

"In BRIDGED MODE, the C 275BEE will produce approximately 330W into an 8 ohm loudspeaker. In this mode, the amplifier sections will react as though the speaker impedance has been halved. Low impedance speakers (under 8 ohms) are not recommended when using Bridge Mode as these may cause the amplifier’s thermal cut-out to operate if played at high levels".

I currently have my eyes on a pair of 6 ohm speakers (CERWIN-VEGA XLS-15). So these will then obviously be 3 ohms when connected to one bridged amp each. 1 ohm less than recommended. Will this be all right? Anyone have any experience with 6 ohm speakers on these amps bridged? :scratch:

[Puffin]

As far as I understand it (and others may say differently) when you bridge it increases the current draw and gives double the power (or more it is said) into half the non-bridged rating. So as you say the amps will be seeing potentially 3 Ohms or less. If you run the amps with these speakers and they get ridiculously hot then you may want to think again, if they don't then you may be ok.

[Dauntless]

You need to be careful. I tried bridging with a pair of A500's into XTZ floorstanders that are rated 4/8 ohms. One A500 closed down and now has an intermittent fault on it. Most makers of amps that support bridging seem to spectify 8 ohm speakers.

[Firebottle]

I'd agree with this. The equivalent load on each channel is 4 ohms, so if the amp doesn't have specifications for 4 ohm load beware.

The current flow is doubled with 4 ohm loads (8 ohm in bridged) so best not go below.

The other worry could be that a nominally 6 ohm speaker may have dips a lot lower in parts of the frequency range.

[Sabaselfsit]

Thanks guys. I hear you and agree. I will not go below 8 ohms, whatever I will hook them up to in the future.

[Hudz]

I believe the speakers are Bi-wireable so why not just connect them as vertical bi-amped, the Nads should still have more than enough grunt in stereo mode.

Apologies if this seems a bit like teaching your granny to suck eggs but my 270s never ran out of steam in mono or stereo mode

[Sabaselfsit]

Apologies if this seems a bit like teaching your granny to suck eggs but my 270s never ran out of steam in mono or stereo mode

:lolsign:

One amp driving the 15"s and the other amp driving the midrange and tweeters?

[struth]

quite liked Vertical Wiring myself.

[Hudz]

Sounds like it's worth a try, interesting looking speakers those, be a shame to miss out on trying them.

Keep us informed if you get them:popcorn:
:lolsign:

One amp driving the 15"s and the other amp driving the midrange and tweeters?

[Hudz]

:lolsign:

One amp driving the 15"s and the other amp driving the midrange and tweeters?

Yes and that way you get level controls if you use the variable inputs so allowing better room integration or possibly:gig:gig stylee:partytime: bass:D if that floats your boat

[Dauntless]

Andre, please see your private messages re a question about Bergen Hi-Fi dealers:)

[Sabaselfsit]

Sounds like it's worth a try, interesting looking speakers those, be a shame to miss out on trying them.

Keep us informed if you get them:popcorn:

Yes, I have been listening to them in the test room in the shop. Very impressed. If you want your hair to stand out, but at the same time good sound quality I think there is not much else that play better for the price. They were test winners in the biggest hifi magazine here in Norway. Here is a translation of the review=

"XLS is the name of the American manufacturer's new top series, and XLS-15 is the second largest model with its 15-inch woofer. Even greater is XLS-215 with two 15". They are also much larger and require more amplifier power than XLS-15 to function optimally. Then it quickly turns expensive.

XLS-15 is more than big enough. 103 cm in height, while they build as much as 43 cm in width and 47 cm in depth. For optimal control you can BIAMP them, thanks to double terminals.

Sound quality: Cerwin-Vega's are something for themselves. Where the other speakers can be a little round in the bass and well cautious in the midrange, the XLS-15 have a totally different style of play. There are a lot's of midrange while the bass are hard hitting as Lennox Lewis.

Bass response is by no means the deepest, but in return there is extreme snap in the in between bass area, where the bass drum feel at home. And the bass is so fast, it enables the speakers to stand up to the back wall. With these it is actually an advantage as the bass becomes fuller.

Rage Against the Machine rock hard, both bass guitar and drum set are planted in the chest. Besides guitar riffs sound better than with the other speakers, except perhaps JBL ES100. In addition, the roaring voice of lead singer Zach de la Rocha are more right in the face for us with CV.

Cerwin-Vega are also the most time-linear speakers in the test, the treble and midrange hit your ears at the exact same time, which is important for the psychoacoustic placement of instruments. Listen to Frost's "Days Like These", a quiet electronic tune with a big synth landscapes that surround the voice of Aggie Frost. XLS-15 placing her voice better in the center than both Dyna Voice Finale 10 and Fence Boost 212, while synth sounds are clearer around her.

The CV is missing, an airy treble. Little bit muted at the top, making the soundscape less than we would like, and if you are fond of listening to triangles and harps, this is not the speakers for you. They also have a resonance in the lower midrange, which can specifically be detected with the slightly dark timbre of male voices of the deeper kind. Nevertheless, it has little impact on us. The speakers can play insanely loud and with fun factor of dimensions.

There is something very special about the sound of Cerwin-Vega and XLS-15 is no exception. These are speakers that hit you so hard that you almost get scared. The bass is not as deep, but it beat rock hard and reinforced between bass gives the illusion of deep bass.

All music is very entertaining on XLS-15. Besides, the speakers are very phase correct so that the instruments are placed punctual in the soundstage. Not the most airy treble reproduction gives a more narrow stereo perspective, but on the other side it also makes these speakers not sharp cutting your ears when it's loud. This in our ears the best in the test."

Amp used in the test= Hegel H200. Other speakers in the group test were= Fence Boost 212, JBL ES100, Dynavoice Finale 10 Tower, MTX TP2400, Jamo S 608, Magnat Monitor Supreme 2000.

[Macca]

Looks like a lot of speaker for the money. http://www.cerwinvega.com/home-audio/floorstanding-speakers/xls-15.html