Disconnect the passive crossover of a 803S or 804S?

[Horacio]

I'm looking at upgrading to 803S or 804S for stereo hi-fi. I've been also reading about the benefits of bi-amping, and how I would need to use an active crossover and remove/disconnect the passive crossover that is built into these speakers. Has anyone done this? How? What were the results? What active crossover did you use? Is this easier to do in the 803S than in the 804S?

Thank you guys!

Horacio

[RobP]

Horacio, You can Bi-amp these speakers without bypassing the passive crossover, which I would suggest, B&W has done a great job in designing the crossovers for these systems. Here is what B&W says about active systems.

Can I make my speakers active?

There is no doubt that active crossovers offer greater flexibility than passive types. You can do exotic things like put in delay to compensate the difference in distance to each driver's acoustic centre or even steer the optimum response quite readily. You can put in variable controls to partly compensate room acoustics. The complex speaker load does not interact with the filter response, as is the case with passive designs, so it is easier to get the shapes you want without worrying about the speaker system impedance.

However, a fully active design is more expensive to execute, it removes the customers ability to choose a different electronics brand and the ability to use the same amplifier to drive another set of speakers in another room. So passive designs have their place and, designed properly, give excellent results.

When considering converting to active, you have to remember that good crossovers, be they active or passive, are custom designed for the drivers used and the particular enclosures in which they are mounted. You can get off the shelf active crossovers, but we do NOT recommend these for high quality audio unless they are purpose designed for the system. If they are not, they will not have the correct in-band equalisation for the drivers' natural responses, compensate for the acoustic centre positions, or match the phase through the crossover region.

There is often a good deal of hacking required to the speaker itself. You have to remove the passive crossover and give direct connection to each of the drivers. You may be into serious woodwork if, for example, you have a 3-way speaker that only has two pairs of terminals for bi-wiring.

The bottom line is that, unless you have access to the facilities to properly design and execute an active circuit for yourself and measure the acoustic results, don't do it! We cannot unfortunately offer active designs equivalent to our passive ones.

[Horacio]

Thank you, Soundgravy.

So it seems all I've been reading about the significant sonic advantages of actively bi-amping are pretty much only practical for DIY enthusiasts building their own pieces.

Have you passively bi-amped 803S or 804S? With two identical amps? Did you find a meaningful difference in sound? Some sources encourage the use of identical amps, while others recommend using solid state for bass and tube amps for mids and highs. Any thoughts?

Thank you again!
Horacio

[RobP]

Hello Horacio, I myself have not done this, I do believe that a couple of guys here have, and it really took the sound to another level, but they would have to chime in here and tell you the benefits from their perspective.

Robert P.

[NonSense]

Horacio

Active Crossovers are not limited to DIYers, but the user must have made this decision at the onset of choosing their system components which would readily allow this type of configuration. Even B&W has produced speakers with external crossovers, but only in their limited edition signatures or Nautilus showpiece.

Regarding Bi-Amping with passive networks, the benefits can only be realized by trial and comparasin. Your ears will let you know.

Keep in mind ever situation is different. If you have the amps on hand or just wish to add a 2nd amp, this is one scenario. However, if you are starting from scratch and are addressing your power needs I would strongly suggest that you also consider a single higher quality amp instead of two lower quality.

Many people will attest for example that a single $2x(dollar) amplifier will outperform two $1x(dollar) amps in a passive bi-amp arrangement. Since the manufacturer doesn't need to spend additional resources on a 2nd chassis and packaging material you see the benefit if much of the additional resources being placed into higher quality components. (On the downside, many of the higher priced products will suffer from lower volumes impacting higher fabrication costs) It's always a trade, but in general, many attest that a single higher quality amp will outperform two inferior amps.


Enjoy your research