Combine 4 amplifier channels into one?

[thylantyr]

How do you combine 4 amplifier channels into one powerful
channel ?

http://www.arkada.com/items/gravity8g1000.pdf

Technical data
RMS Output power in single mode @ 4 Ohms: 8 x 83 Watts
RMS Output power in single mode @ 2 Ohms: 8 x 130 Watts
RMS Output power in bridge mode @ 4 Ohms: 4 x 260 Watts
RMS Output power in parabridge mode @4 Ohms: 2 x 330 Watts
RMS Output power in parabridge mode @2 Ohms: 2 x 520 Watts
Peak output power: >1500 Watts total
Max input Current (@13,8 V): 100 A
Idle current (no signal): 1,2 A
Fuse: 2x40 A
Total Harmonic Distortion (THD): <0,05 %
SNR: >89 dB(A)
Freq.Response (bypass mode): 7 Hz-50.000 Hz
Stability (single/bridge/parabridge): 2 /4 /2 Ohms
Input Sensitivity: 250 mV-6 V
Warranty: 1 Year

Parabridge mode:
Due to the spezial crossconection of those 4 Amp sections in 1 Channel mode the combined solution is again 2 Ohm stable.

http://ampguts.realmofexcursion.com/Xetec_Gravity_8G-1000/

 

[Nelson Pass]

If you run the channels series and parallel, you can quadruple
the output even into as low an impedance as a single channel
would drive. I've done it a few times, and it works like glue

 

[Leolabs]

search for"AN1192".

 

[thylantyr]

I was wondering if they used a different methodology.

 

[consort_ee_um]

Could it be this technique?
http://www.edn.com/index.asp?layout=ednPDF&file_name=/contents/images/330071.pdf

 

[gtforme00]

It appears as if the "modules" for that amplifier simply change the input topology to set the channels up for bridged, or bridged parallel mode.

The end result is what Nelson described above, two amps in parallel bridged with two additional amps in parallel having opposite phase.

In reality it can be difficult to balance the bridged configuration, and that is where Leolab's recommendation for reading AN1192 will be useful.