I recently bought a Integra DTR-70.1 a/v reciever and i have the option of 4ohm or 6ohm. 6ohm include 6 to 15ohm impedance speaker. So i have a pair of M80 from and VP150 center so is there any problem to set my speaker to 4ohm or should i stick with the option 6ohm ?

Also, this amplifier can be bi-amped, does it really affect something for stereo listening to my M80, anyone has notice an improvement ?

Thanks

Hi Philippe - Most of the opinion I've seen here (and to which I subscribe) is that you should leave your receiver at the 8ohm setting (I suppose the 6ohm setting in your case) and that biamping is very unlikely to be useful, especially when you are using the same power supply for all the channels.

Agree, on both counts.

I concur with all that has been said about this topic. Yamaha use to put these ohm switches on their AVRs which was a waste of space, accomplished nothing in the process and just confused the owner. Reviewers constantly complained that all these switches did when set to a lower ohm level, was restrict the power supply.

Over the years, I have outboard power amps and tried both bi-wiring and bi-amping with many different speakers and quite frankly, if there is any difference in the sound quality, I have yet to hear it.

Haven't tested myself bi-amped mode but indeed i guess it wont change anything anyway. The signal just go out of the amplifier no matter the section so.
I am sure in a blind test no one could tell the difference.

Philippe, both of these points have been discussed here on several occasions. The lower impedance switch or menu setting should never be used, despite the language in the manuals. It's a UL required fire-prevention measure to make overheating less likely. It does this by limiting the voltage output, which as a result limits current and power because of Ohm's Law(maximum power is cut roughly in half). So, the possibility of overheating is reduced, but at the expense of reducing the maximum designed performance.

Again, despite any manual language, the DTR-70(and others making similar claims)can't be bi-amped. There's only one amplifier with one main power supply section outputting through several channels of output transistors which act as valves to send each speaker the amount of voltage required at any instant in time. Connecting a speaker through two sets of output transistors rather than one doesn't double the available power, as some imagine, or increase it by any amount.

Thanks for you time and your answer John.

I've always wondered why someone doesn't take these companies to court on these false technologies if they truely have no merit?

Expert witnesses who can clearly explain how the claims are false are themselves expensive.

Sometimes doing something a little outrageous can avoid the costly court case. I am not sure if anyone remembers but back a few years ago the retired magician, "The Amazing Randy" disputed a cable companies claim of superior performance by offering $1 million dollars to the company if, in a blind listening test, hand-picked mutually agreed upon experts could tell the difference between this so-called high-end cable(it retailed for $7500!)and a run of the mill audio cable purchased in any store. Given the whole episode stretched out over a period of weeks, it got all kinds of publicity in the CE press. Needless to say after agreeing to the test, the company at the last minute, backed out never to be heard from again.

A pretty effective way to get rid of the false claims.

Randy, something I continue to marvel at the irony of is the fact that the one thing in audio that has specific legal regulations, i.e., amplifier power ratings under the FTC regs, and which if ever violated could be the subject of a simple complaint filed even online, is often a subject of suspicion. This is seen on some other boards among the naive who accept, or at least are willing to take seriously, claims about the "sound" of pieces of wire.