Will bridging an RB980 be similar to RB1090?

[Viper1]

Bridge RB980 specified @ 360-380 watts to a stereo RB1090 specified @ 360-380 watts be similar in power?

[Dmantis]

My question back is why?Sound quality is more important is it not?Only a side by side comparsion will tell you your real answer.I have listened to both amps and I believe the 1090 is the best sounding to dats amp I have heard from Rotel.
they both sound great.What kind of speakers are you driving?

[Aussie Geoff]

The RB-1090 will have twice the current reserves!

Viper1,

Rotel amplifiers tend to be stable under load for speakers rated to 4 ohms and cope with the small transient frequency dependent drips to 2-3 Ohms that often occur at points in the speaker bass resonance range or in the crossover area...

Now when you bridge an amplifier each channel sees 1/2 the impedance of a speaker - so an 8 ohm speaker looks like a 4 ohm speaker to each half of the bridged amplifiers. Typically you get a doubling or near doubling in power for each half through the 4 ohm load, so magically a 130w a channel amplifier like the RB981 (which I am familiar with) becomes a 360W mono amplifier...

Now for the not so good bit...

Essentially by bridging you use the majority of the amplifiers current reserves. You will find that the Rotel amplifier can't double again with a 4 ohm load (this looks like a 2 ohm load to each half) and indeed may sound hard or strained at volumes of difficult speaker loads. As a guide the rated power consumption of the RB981 (both channels driven) is 400W - so the 360W is very close to its limit....

Now lets consider the RB-1090. This is rated at 380W per channel into 8 ohm and 700w per channel into 4 ohms… It contains two 1500W transformers… On all but easy loads the RB-1090 will have twice the power reserves of the RB981 or similar and generally sound less strained and better for it….

All that aside – it depends what and why you are asking. For example if you have a RB-1090 for your front left and right channels then using a RB981 or simular for the centre channel is a reasonable move. However to use two RB981 (or similar) instead of a RB-1090 is (in my opinion) false economy…

The RB1090 is a great stereo amp and hard to beat for the money / power combination….

Geoff

[Viper1]

Will bridging an RB980 be similar to RB1090?

Just wanted to know if my existing amp in bridge mode will be "good enough" to power my speakers-SF Grand piano and if that extra cost/upgrade warrants it, If ever I decided to trade-in to the RB1090. I did notice that bridging the amp sounds a bit strained and distorted in the midrange although it plays LOUD.

I don't listen loud but I need amps that even at low level listening produce/controls the bass better.

I would like to purchase or trade to the RB 1090(if a good deal comes up) and/or maybe I'll keep and bridge them(3x RB980) instead to power the center and surrounds.

Thanks to those who contributed.