converting stereo power amps to mono

Do you like the Sonance 260?

Not all amps can be "bridged" and it does not always have desirable results even if it can be done.

I guess my real question is the effect of splitting the output from my pre-amp so that the same information is delivered to the left and right sides of each power amp. Your thoughts?

Thanks for replying.

Cheers,
Jon

I'll answer your question in the next paragraph. But first let me be sure that you realize that if the amp isn't designed for bridging, putting the same information into both channels of one amp, and then connecting a speaker between its two "hot" outputs, will result in essentially zero sound from the speaker (since there will be essentially no voltage difference between its terminals). A properly bridged amp will invert the phase of one channel, and will do that without introducing significant time delay differences between the channels other than the phase inversion.

To answer your question, though, feeding one output channel of the preamp into two input channels of a power amp should not be a problem, provided that the rated input impedance of the power amp is considerably higher than the output impedance of the preamp. With two channels fed, the effective input impedance of the power amp will be half what it is normally.

Also, it would probably be best to do the split at the preamp output, so that you are in effect bi-wiring to the power amp. If you just run one cable from preamp to power amp, and then a short jumper to the other power amp input, the lower combined input impedances of the two amplifier channels might magnify any cable-related degradations of the signal, particularly at high frequencies.

Regards,
-- Al

As a follow-up to my previous post, I took a look at some front and rear photos of the Sonance 260x3, and I see no bridge-mode switch, or any other indication that it is bridgeable.

Regards,
-- Al

Almarg,
Did you mean feed the same signal (mono) to each channel of a stereo amp? If so, you are correct that the output between the 2 hots will be essentially zero, showing only the channel imbalance....which should be inaudible.
If, however you feed a stereo amp a stereo signal THAN go from hot 2 hot, you will get an output. Back at the 'dawn' of multichannel....QS / SQ matrix and such, I would connect a pair of speakers normally as fronts, and another pair, from hot to hot.....put 'em in the back of the room and instant ambiance. No fine tuning possible, but as proof of principle, it worked. I think that was the principle behind the original 'dyanquad'....the speaker adaptor they sold.

Hi Magfan -- Yes, I was referring to feeding a single channel signal identically into both channels of the amp, because that appears to be what the op was asking. I think he was envisioning using two stereo amps, one per channel in bridged mono mode, to get greater power per channel. My basic point was that you can't do that unless the amp is designed for bridging, which would mean that it is capable of being set to invert phase on one channel.

I do recall the technique you are referring to. I think the adapter you are referring to was a David Hafler thing, and the technique was generally attributed to him. I had no experience with it, though.

Regards,
-- Al

In every case where I have tried two lesser quality amps as opposed to one higher quality amp, the single, better quality amp has outperformed the pair. I would recommend finding an outstanding stereo amp. Get one with vastly higher power, and the presentation will radically change for he better.