Biwirable speakers, phasing

I'm currently performing a few experiments, since my system is now being seriously limited by room interactions.

Biwirable speakers give the option of running the drive units in the speaker out of phase, which seems to have some interesting effects. I have come to no conclusions yet, but I am going to continue experimentation...

 

Sonus Faber and Proac speakers have the drivers wired out-of phase, at least some of them, including those I have, to integrate better, they say...

 

It's a common practise, depending on crossover design.

 

Why would you want to run drive units out of phase? Surely that would sound cack? Like when I accidentally connected my car speakers out of phase, they sounded distorted and had no bass.

 

Paul - I mean running the tweeters in phase with one another, but out of phase relative to the bass drivers. Due to crossover design, you have a phase shift between these drivers anyway, and swapping the phase of the tweeters doesn't have the same effect that having one speaker out of phase to the other does.

 

If speakers are wired out of phase it will be the treble and bass units on each speaker, not the L&R channels out of phase.

I am not an expert, but a loudspeaker crossover can often introduce phase shifts. By wiring woofer and tweeter out of phase it is possible to get better driver integration.

 

Hmmm.... this topic has me intrigued to see what effect this would have on my 11L's, but I'm just wondering if running drive units out of phase can cause any damage?

 

No

 

I am sure it wont cause any damage...

 

Well my curiosity go the better of me and I switched my jumpers round to put the drivers in my 11L's out of phase. Having done a brief A/B/A/B comparison with a couple of CDs my preliminary impression is that treble seems less prevailing and upfront while the bass is more evident but at the same time not overbearing. However these impressions might just be the usual psychological desire to hear something different. I'll need to live with it for a while and possibly rope in some (un)willing test subjects to see if they can tell the difference .

 

I guess the question is why do you feel the need to play around with the phase of the tweeter? Are you unhappy with the sound in some way? If so, whats wrong? If you are already happy with the sound, i'd be tempted to leave the speakers working as the designer intended

 

I'm not unhappy with the sound. I guess I'm just one of these people who likes to experiment and play around with variables/settings to see what the various effects are and if there are any benefits . But I guess you're right, the designer probably has a better idea than me of how loudspeakers work.

 

Well, there's no harm in a bit of experimentation!

 

Yup.
The classic second order crossover design leads to a 180 degree phase shift at the crossover freqiency, so many manufacturers using this design reverse the polarity of the tweeter to give equal phase response through the crossover region, sacrificing the phase relationship between much lower and much higher frequencies.
It's a compromise, but it works.

 

We've been here before. Many speakers sound crap biwired, but designers still provide this ability.

 

Can someone tell me the point of bi-wiring? I can see that having a biwirable crossover is useful, as you can bi-amp the speakers - however whats the point of running two cables from the same amp, other than reducing the impedance of the cable? Ive got my AE 120s triwired and am only keeping the extra 25 miles of cable in the hope that one day I'll get a power amp.
Also can you use active crossovers with speakers that already are fitted with a crossover?