converting stereo power amp to balanced mono block

[tannoydc]

Hello
I have two nad c272 power amps and I was wondering if they could be run as balanced mono blocks. The input hot signal would go to the left amp input and the cold to the right and ground to ground. The output of the left + terminal would go to the + speaker terminal and the right + terminal would go to the - speaker terminal and the amp's - terminals would be joined. I don't know if this is possible and would appreciate some input.
tannoydc

 

[stratus46]

Hello
I have two nad c272 power amps and I was wondering if they could be run as balanced mono blocks. The input hot signal would go to the left amp input and the cold to the right and ground to ground. The output of the left + terminal would go to the + speaker terminal and the right + terminal would go to the - speaker terminal and the amp's - terminals would be joined. I don't know if this is possible and would appreciate some input.
tannoydc

Look up 'bridge amplifier'. Not all amplifiers are suitable for this mode. Remember that in bridge mode, each amplifier 'sees' 1/2 the impedance of the load so your 8 ohm speakers look like 4 ohms to each channel. No paralleling of speakers in this mode (there are some amps OK with this). That's the bad news. Good news is the power quadruples so a 100 watt amp becomes 400. It will get _hotter_ too.

G²

 

[tannoydc]

Thanks for taking time to reply stratus46,
The nad c272's are bridgeable, but what I am wanting to know is if they can be used as a balanced not bridged mono block. The reason being is that I have balance outputs on my dac and cd player and I want connect the system up balanced from source to preamp to power amp to loudspeaker.
tannoydc

 

[stratus46]

Thanks for taking time to reply stratus46,
The nad c272's are bridgeable, but what I am wanting to know is if they can be used as a balanced not bridged mono block. The reason being is that I have balance outputs on my dac and cd player and I want connect the system up balanced from source to preamp to power amp to loudspeaker.
tannoydc

I'm sure you can do that if you're only using the one source but you would need a balanced preamp with balanced inputs though most source gear is unbalanced. It's best if the balance is truly balanced as you don't want one half of your amp clipping before the other half though in reality, you never want it to clip. Certainly no harm in what you want to do though I believe marginal. But it will make you feel better and I don't mean 'feel' as a pejorative. We all do some things that way.

Just as an FYI, commercial routing switchers for balanced audio nearly universally convert the inputs to unbalanced and convert it back into balanced at the output. If you think about it, a 256x256 router has 65536 crosspoints and going balanced would quadruple that and nearly nobody would be able to tell the difference - except the accountants!

G²

 

[tannoydc]

Hello stratus46,
It seems your bridging idea is correct, one channel must be out phase to the other. This is done internally in the c272 when you switch to bridge mode and the only difference is that I will be doing it externally. Thanks very much for your help.
tannoydc