Belle upgrades questions

[brians7]

I have been wanting to upgrade my Belles and changing the K500 squawker Horn in not a option. So some thoughts are first replacing the woofers with Eminence Kappa-15C. Then second replace the tweeters with ALK and Fastlane Audio Eliptrac HF horn with B&C DE120. And third here is the question is there any reason to not rise the crossover to 600Hz on the woofer now that the Kappa-15c easily can reach that high and lowering the tweeter to 4000 sense the K500 horn will not be changed? Also would there be any noticeable difference switching to the new A-55G Midrange Drivers?  Thanks Brian

[Chris A]

See:

This will give you the greatest upgrade in the sound of your Belles without changing any horns or drivers. 

 

If you want to change horns and/or drivers, using an active crossover will give you the ability to correct the frequency response, delays, and crossover frequencies to accommodate any of those changes.  I recommend a 2-in, 6-out crossover if you are using a stereo pair of Belles. I don't recommend Behringer DCX2496. If you use miniDSP, I'd recommend a money-back guarantee if it's too noisy.  Battery power to miniDSP apparently solves noise issues.

 

Here is a USB microphone that you can use with REW freeware to find the correct settings for your active crossover using new horns or drivers: https://www.minidsp.com/products/acoustic-measurement/umik-1

[Chris A]

1 hour ago, brians7 said:

And third...is there any reason to not raise the crossover to 600 [Hz] on the woofer now that the Kappa-15c easily can reach that high and lowering the tweeter to 4000 [Hz] since the squawker will not be changed?

While you can get the Belle to cross at even higher than 600 Hz, note that the tradeoff is mismatched bass bin polar coverage angles to the midrange polar coverage angles in the crossover band.  This is audible.

 

Lowering the tweeter crossover below 5 kHz is an issue of how the tweeter sounds, I've found experimentally. It sounds rough to my ears.  I recommend 4.9 kHz using steeper slope crossover filters (24 dB/octave Linkwitz-Riley or steeper filters). 

 

I recommend a Beyma CP25 tweeter, for instance, to cross-over at a lower frequency. 

[brians7]

I recommend a Beyma CP25 tweeter, for instance, to cross-over at a lower frequency

Yea but the Beyma  tweeters are not a bolt in replacement driver and would require modification to the tops. That's why the ALK and Fastlane Audio Eliptrac HF horn with B&C DE120 are the ones I am looking at.

 

While you can get the Belle to cross at even higher than 600 Hz, note that the tradeoff is mismatched bass bin polar coverage angles to the midrange polar coverage angles in the crossover band

I crossed my LaScalas over at 700Hz actively using a Marchand XM44 and ALK Universal crossovers and still think that's how they sounded the best. It could have ben the 24db slope that made the deference. I am not wanting to cross higher than 600Hz just asking if anyone had so thoughts or experience crossing Belles at 600Hz  might there any improvement crossing 600Hz over 500Hz     

[Chris A]

I crossed using 500 then 600 using EV Dx38: the frequency response and phase were smoother using 600 Hz. The bass bin-midrange polar coverage mismatch got worse, however.

 

Have you measured this in the past on your Belles?

 

I've found the the "choosable" interference bands of both crossover regions of the Belle are not very wide - less than 1/4 octave effectively in choosing the crossover points, and really less than 1/6th octave of latitude when you actually listen to the results: mono is the best way to hear issues.

 

Chris

[brians7]

OK using REW how do you measure polar coverage? And than you for helping Me Chris

[Chris A]

I used a turntable - outside.  It consisted of the base of a bar stool...

 

Works well, and stows nicely after you're over taking the measurements into nice furniture. 

 

When you measure the distance between the mouths of the Belle bass bin, at the point where that center-to-center distance equals 1/3 wavelength--that's where the polars narrow considerably and the "lobing" becomes a real issue.  At 17 inches (give or take), that's about 270 Hz when things start to lobe.

[brians7]

LOL it a little late to take the Belles outside tonight

[Honeybadger]

I would stick with the OEM woofer if it is in good operational condition and replace the tweeter and replace or recap crossover like your original plan.

 

Whatever you decide, enjoy those Belles.

 

Side note, keep all of the oem parts in case you need to go back to stock.

 

HB

[brians7]

So I ordered the new John Allen A-55G Midrange Drivers from Bob. I am looking forward to listing to them with my new amps http://www.diytube.com/phpBB2/viewtopic.php?f=3&t=6914

Guess the next upgrade will have to be tweeters  Fastlane Audio Eliptrac HF horn with B&C DE120.

[brians7]

Here is a link to the schematic http://www.audiokarma.org/forums/index.php?threads/parallel-kt88-se-by-kegger.650780/#post-8669164 if any one is interested