Dear Members,

I am new to bi-amping.
My sistem is as follows:

- home made preamp in class A (fet)
- one rotel rb970bx
- one yamaha m-70
- a cheap Denon cd player (soon to be replaced)
- an active crossover (2 way stereo)
- Mission 752 speakers

I decided to bi-amp the Mission 752 that I have and so I did the
following: I wired the preamp to the active crossover and then from the
active crossover I sent the wires to the two different power amplifiers
(Rotel for the bass, Yamaha for the midium-high).

I have just called Mission, the factory (+44 (0) 845 4581122) asking if
they can recommend me a particular frequency where to split the bass
from the rest. They did not know what I was talking about. I explain
what I did with the same words I used in this email and they told me
that I don't need the active crossover to bi-amp the speakers.

Maybe I missed something.

Can any of you shed some light on this?

I thank you in advance for your time.

David

Le Fri, 09 Sep 2005 03:50:00 +0000, dbavim a =E9crit=A0:

Dear Members,
=20
I am new to bi-amping.
My sistem is as follows:
=20
- home made preamp in class A (fet)
- one rotel rb970bx
- one yamaha m-70
- a cheap Denon cd player (soon to be replaced)
- an active crossover (2 way stereo)
- Mission 752 speakers
=20
I decided to bi-amp the Mission 752 that I have and so I did the
following: I wired the preamp to the active crossover and then from the
active crossover I sent the wires to the two different power amplifiers
(Rotel for the bass, Yamaha for the midium-high).
=20
I have just called Mission, the factory (+44 (0) 845 4581122) asking if
they can recommend me a particular frequency where to split the bass
from the rest. They did not know what I was talking about. I explain
what I did with the same words I used in this email and they told me
that I don't need the active crossover to bi-amp the speakers.
=20
Maybe I missed something.
=20
Can any of you shed some light on this?
=20
I thank you in advance for your time.
=20
David

Hi David,

there are two ways of bi-amping : passive and active.

- Active bi-amping (the filter feeds the amps) means the filter (either
active or passive) is between pre-amp and amp.

- Passive bi-amping (the filter is feeded by the amps) means the filter
(either active or passive) is between amp and driver (either inside or
outside loudspeaker).

If you have loudspeakers with built-in and non-bypassable filters (I gues=
s
this is the case for your Mission 752), you cannot bi-amp your
loudspeakers the active way, you have to bi-amp it the passive way.

That is you have to dispose of two power amps (identical ones, ideally)
with the same gain and the same sensitivity, or with level potentiometers=
..

Then your Preamp feeds two amps (in parallel) which themselves feed
directly the "bass" ins and "treble" ins of your loudspeakers. The first
amp is for bass (stereo : L+R), the second is for treble (stereo, L+R)

Hi Didier,

I did it: I disconnected the internal passive crossover and so I
managed to bypass it. The results are simply great: you cannot really
compare the sound.

I simply had the misconception that bi-amping implied bypassing the
crossover, but it was clearly not the case. I can now tell that the
best thing of the Mission 752 speakers is the fact that the crossover
is easy accessible (and so you can disconnect it easily!).

Thanks for your reply,

David