Speaker for Bi-Amping

[mikegm47]

Hi All,

First ever post . . . . .

I've been considering exploring bi-amping and active crossovers.

I thought I might use a pair of Wharfedale 505.2 that I have but I can't see how to open them up to remove the passive crossover, etc. They have no visible external fixings - not even around the drive units. Surely they're not completely glued together ?

So can anyone tell me how to open them up without damaging them ?

OR can anyone suggest a sensible LS that is amenable to modification. Ideally it would have to be a 2-way unit because I would prefer to build four channels of electronics rather than six. It would also have to be good enough to show some benefit from the modifications and be readily available on the second hand market.

BTW I'm considering the Elliott Sound Products MOSFET amplifier, Project 101 here:
http://sound.westhost.com/projects-1.htm
and an active crossver either from ESP or one of the ones on the Linkwitz web site.

All comments and suggestions gratefully received.

Mikegm47

[sreten]

As far as I recall The 505.2 uses a bayonet mounting
arrangement for the drivers, (similar to a camera lens).

To remove them you need to arrange some method
of twisting the drivers in a circular fashion.

IMO a 2 way is not particularly worth bi-amping,
and you can't simply substitute an active c/o with
classical filter functions for a passive 2 way crossover.

IMO a 3 way is a much better idea but with a mid/treble
passive crossover, however if the Mid has BSC ideally this
should be removed and implemented actively.

Class A or valve for mid/treble would be nice.

But what speaker ? a fair conumdrum.

TBH I can't think of a particularly suitable good loudspeaker.

Edit :
http://www.richersounds.com/index.ph...l.php&p=301821

At the price could be worth a punt - there's lots you could
do to them to improve performance if you know what you
are doing.
If the bass / mid crossover is first order (more than likely)
then you could use passive line crossovers at the input to
your amplifiers, which would make adjustment easy.

sreten.

[mikegm47]

Thanks sreten,

Bayonet mounting of the drivers is consistent with some strange blind holes in the metal ring around the drivers, probably for locating a removal tool.

With regard to the crossover itself, I had two thoughts. The first was to extract the original one and then measure or calculate it's response and use it as a starting point. Alternatively, measure the response of the individual drivers in the enclosure and design a suitable crossover from scratch.

Although neither approach is particularly easy, it should be easier than designing a passive crossover because of the isolation between the active crossover and the driver load.

The LS from Richer Sounds certainly look interesting !

Best regards,

mikegm47

[mikegm47]

sreten,

BTW, Why do you say that two-way units are not worth bi-amping ?

My thinking was that the benefits of bi-amping were: better behaviour around the crossover frequency, better driver damping and arguably the possibility of phase coherence. These should be equally applicable to 2-way and 3-way units ?

Best regards,

mikegm47