[Paul McNeil]

I recently tried bl-aming one of my 3.6 Maggies, in use as a center channel, with a Crown XLS 2500, using the passive crossover connections supplied on the box containing the crossover. Not much improvement, and not surprising.

Then I bi-passed that box, and used the electronic crossover built into this Crown amp, at 2600 Hzt, after removing the box and all of that passive stuff..

Amazing transformation. Transparency reigns. Center channel voicing is now crystal clear.

The only quibble was that now I could rattle the panel with low bass input. I now have the cross-over set at 80 Htz, and no more rattle.

That passive cross-over is worth getting rid of, in my opinion.

[Jazzman53]

Glad to see another convert to active bi-amping.  There's nothing like getting rid of that passive inductor and giving control the bass to the amp for a change, not to mention restoring correct phasing between drivers.     

[Davey]

Paul,

Your post doesn't make much sense.  The external crossover box for the 3.6 handles the woofer/mid transition and the crossover frequency is near 200Hz.
The midrange/tweeter crossover is internal to the speaker and up at a higher frequency.  (Near 2600Hz.)  It can't be disabled without breaking into the speaker and rewiring.

Also, the Crown XLS amps (IIRC) only have the capability for LR4 electrical slopes.  This would be quite a bit different than those implemented by the stock mid/tweet 3.6 crossover for either woof/mid or mid/tweet slopes.

Here's an interesting active equivalent crossover for the 3.6 I posted on the MUG forum about 16 years ago.  It shows the transfer function plot of the stock crossover.
http://www.integracoustics.com/MUG/MUG/tweaks/davey/mg3.6xo.htm

I suggest to revisit your thinking on this and make sure you're really doing what you think you're doing.

Cheers,

Dave.

[Paul McNeil]

Thanks, Dave, for doubting me!

I chose the crossover frequency based on the Magnepan manual..."Set your electronic crossover at the following points and slopes: Low Pass: 18dB per octave at 250Hz
High Pass: 6dB per octave at 200Hz".

But I realize this does not translate perfectly to the Crown's spec, though it may by chance to my room.

Nevertheless, I am sure that I like what I hear, and that it is much better than what I heard through that box (containing the passive crossover).

I'm also sure that any fuss about amps and cables, etc., pales by comparison to my (amateurish} replacement of that passive crossover.

I'll have a look at your post, but am technically-challenged...

[Letitroll98]

So I'm a little confused here.  First you set the low pass filter on the amp for 2600 Hz and then lowered it to 80 Hz because the bass panel was buzzing?  Then you state the Magneplaner recommendation is for 250 Hz?  I have to be missing something here, can you help clear it up?

[Paul McNeil]

My apologies, the x-over on the Crown is set at 260 htz, NOT 2600.

The pre/pro low passes (80 htz) bass to the subwoofer.

[Davey]

Paul,

That does make much more sense now. 

My comment above regarding slope change still applies though.
You should try reversing the polarity of your woofer connections (while leaving the main panel connections the same.)  Since you've altered the roll-off slopes from stock, the Magnepan relative wiring polarity between woofer and main-panel is no longer correct...theoretically.  This polarity reversal will correct the panel integration to properly match the LR4 slopes your Crown amplifier has.

Dave.

[Paul McNeil]

Thanks, Davey, I'll definitely give that a try and get back to you. Thanks!

[Paul McNeil]

"You should try reversing the polarity of your woofer connections (while leaving the main panel connections the same.)  Since you've altered the roll-off slopes from stock, the Magnepan relative wiring polarity between woofer and main-panel is no longer correct...theoretically.  This polarity reversal will correct the panel integration to properly match the LR4 slopes your Crown amplifier has"

Dave, This IS an improvement. Audyssey no longer measures a major deficit centered around 2600 htz (why this frequency range). And I have improved clarity at lower volume especially off axis (important, as I'm using this Maggie as a center channel, behind a sound transparent screen). So, Many thanks! Paul

[Davey]

Confusing again.  At this point I can't tell if you're messing with me or not.
Whatever.  Good luck.

Dave.

[G Georgopoulos]

"You should try reversing the polarity of your woofer connections (while leaving the main panel connections the same.)  Since you've altered the roll-off slopes from stock, the Magnepan relative wiring polarity between woofer and main-panel is no longer correct...theoretically.  This polarity reversal will correct the panel integration to properly match the LR4 slopes your Crown amplifier has"

Audio signal is AC,polarity of driver is neutral with ac signal,sorry but don't have experience with crown amps,
even in multi-driver speakers polarity doesn't matter,
mho 

[Davey]

Audio signal is AC,polarity of driver is neutral with ac signal,sorry but don't have experience with crown amps,
even in multi-driver speakers polarity doesn't matter,
mho 

Yet another topic you're clearly in over your head with.
You're an entertaining fellow though. 

Dave.

[G Georgopoulos]

You're an entertaining fellow though. 

Dave.

Thank you Sir, I appreciate...

[*Scotty*]

A start on understanding phase shift in crossovers. Read more about it!
Here's the link: http://sound.whsites.net/ptd.htm
Scotty

[G Georgopoulos]

A start on understanding phase shift in crossovers. Read more about it!
Here's the link: http://sound.whsites.net/ptd.htm
Scotty

Hi Scotty

I was reffering to single driver polarity on ac and driver freq domain

[Paul McNeil]

"Confusing again.  At this point I can't tell if you're messing with me or not.
Whatever.  Good luck.

Dave."

Dave, no, I wasn't messing with you. And yes the severe 2600 htz centered deficit before reversing polarity is confusing for an electronics-challenged idiot like me, but, if Audyssey is accurate, real.

Have you been 'messing' with me?

Paul

[Paul McNeil]

"A start on understanding phase shift in crossovers. Read more about it!
Here's the link: http://sound.whsites.net/ptd.htm
Scotty"

Thanks, Scotty, had a look. It seems to me the ripples shown in Fig. 6 could explain my problem. But I have to admit that this stuff is a bit above this head.

Paul

[JohnR]

Screenshots would probably help, assuming you're asking for advice.

[Davey]

The existing mid/tweet crossover has been left intact this whole evolution, yes?  If so, then polarity changing the woofer only should have caused a measurable change only in the woof/mid crossover region.....approximately 250Hz.
With your Audyessy setup in the mix it seems you have too many variables at work and are confused with the results.  I suggest to disable the Audyessy setup (and any other external processing) to properly evaluate JUST this response change associated with the altered crossover alignment.

Dave.

[Davey]

Hi Scotty

I was reffering to single driver polarity on ac and driver freq domain

Your trolling of these threads with obfuscating and ignorant remarks is not appreciated.

Dave.