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Question for crossover gurus.


Dave A

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I have been rebuilding AA crossovers for the DE120 and either disconnecting or removing the Zener diodes since I figure with the higher wattage capacity of the DE120's they are not needed anymore. In the tweeter side is there a reason to stay with the AA and the two 2uf caps and the .245uh coil or would switching to an A type with just the single 2uf be just as good?

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13 minutes ago, tigerwoodKhorns said:

I am no crossover guru, but I have built type As and added the same fuse that ALK used in his design.  I needed it once, at relatively low volume a pot on my old Peach preamp made some noise and blew the fuse.  I had the volume pot replaced and only needed to replace a fuse, not a tweeter too.

What type of tweeter?

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Dave,

  The slope of the crossover is different. The steeper slope is better measurement wise. Some feel the lower order crossovers match better at the crossover frequency and cause less phase shift. 

   I like the lower crossover point and steeper slope. Have owned speakers with first order crossovers and speakers with 2nd, 3rd, and 4th order filters. Implementation seems to be the main factor. Well done they all can sound good. 

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The fuse on the Universal was for the woofer, not the tweeter. He no longer uses it.

 

The Type AA images better because there is less overlap, and will not send the tweeter into distress as soon. The Type A is great, but best reserved for those who listen at lower levels.

 

Zener diodes and the 561 autobulb are best for tweeter protection.

 

With these new tweeters that everyone is using, why not move to the correct first order value -- which is 3.3uF.

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6 hours ago, Dave A said:

I have been rebuilding AA crossovers for the DE120 and either disconnecting or removing the Zener diodes since I figure with the higher wattage capacity of the DE120's they are not needed anymore. In the tweeter side is there a reason to stay with the AA and the two 2uf caps and the .245uh coil or would switching to an A type with just the single 2uf be just as good?

 

No, the Type A is not better and the Type AA filter has EQ built in it to smooth and attenuate the 105 dB K-77-M. Depending on the horn its bolted to, the DE120 probably doesn't need the eq.  I'd be looking at a 3rd order Butterworth for it.  Then, I'd look at dropping the crossover to 4500 +/- 500 Hz and rolling off the squawker at that frequency with at least a 1st order filter. You'd want to test to see where your tweeter blended the best.  With care you might even match the horizontal dispersion of the 2 drivers. 

 

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51 minutes ago, JohnA said:

 

No, the Type A is not better and the Type AA filter has EQ built in it to smooth and attenuate the 105 dB K-77-M. Depending on the horn its bolted to, the DE120 probably doesn't need the eq.  I'd be looking at a 3rd order Butterworth for it.  Then, I'd look at dropping the crossover to 4500 +/- 500 Hz and rolling off the squawker at that frequency with at least a 1st order filter. You'd want to test to see where your tweeter blended the best.  With care you might even match the horizontal dispersion of the 2 drivers. 

 

This is precisely what I'll be doing with my Super Cornwall and Super Heresy 2.0 mods. I'll be updating the SH2.0 with DaveA's gorgeous new Walnut Machined Tweeter Horn Lenses (MWHLs).

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The de-120 is 106dB/2.83v, so it's well suited for the AA. 

 

I didn't like the sound with the 4500 crossover point, and neither do a lot of other people. I quit offering the option years ago because I got tired of the complaints. Four full octaves out of the midrange sounds nice, and moving 25% of the signal to the tweeter really changes the character of the top section. The AK-4/5/6 gets away with it because of very steep slope.

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5 hours ago, Deang said:

The fuse on the Universal was for the woofer, not the tweeter. He no longer uses it.

 

The Type AA images better because there is less overlap, and will not send the tweeter into distress as soon. The Type A is great, but best reserved for those who listen at lower levels.

 

Zener diodes and the 561 autobulb are best for tweeter protection.

 

With these new tweeters that everyone is using, why not move to the correct first order value -- which is 3.3uF.

Replace both 2uf's with these? What do you think of using the DE10 with the AA?

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I was talking about the Type A. Change the single 2uF to a 3.3uF. Also, run it off input positive instead of the backside of the 13uF. It's worth a listen. Don't do this with the K-77. 

 

I have no experience with the de-10. I'll check the cut sheet. 

 

Edit: de-10 curves ugly, and it's pretty hot on the lower end of its response. 

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9 hours ago, Deang said:

I was talking about the Type A. Change the single 2uF to a 3.3uF. Also, run it off input positive instead of the backside of the 13uF. It's worth a listen. Don't do this with the K-77. 

 

I have no experience with the de-10. I'll check the cut sheet. 

 

Edit: de-10 curves ugly, and it's pretty hot on the lower end of its response. 

Going by the manufacturer's curves is only ONE side of the data. My curves are based on that particular driver bolted to DaveA's ACTUAL Large Horn Lens, the "other half" of the sonic equation. They are not ugly. They are the best and cheapest driver to use with that lens, if you have the space.

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It's understood that it wouldn't plot the same on a different horn - I was just comparing both drivers on the same horn by the manufacturer. I don't see enough price difference between the two drivers to justify dropping back to what might be an inferior driver. 

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  • 1 month later...

Please excuse my jumping in here but I have a very similar scenario as I wrap up a re-build of my Speakerlab Khorns and associated crossovers.

On 4/9/2019 at 8:00 PM, Deang said:

I was talking about the Type A. Change the single 2uF to a 3.3uF. Also, run it off input positive instead of the backside of the 13uF. It's worth a listen. Don't do this with the K-77. 

 

I was going to initially just do a Type A build with better caps, but after reading this it sounds like I may want to take advantage of the Crites CT-120 tweeters with a few tweaks.  Deang, what are you saying with that 2nd sentence?

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On 4/9/2019 at 9:21 PM, Deang said:

The de-120 is 106dB/2.83v, so it's well suited for the AA. 

 

I didn't like the sound with the 4500 crossover point, and neither do a lot of other people. I quit offering the option years ago because I got tired of the complaints. Four full octaves out of the midrange sounds nice, and moving 25% of the signal to the tweeter really changes the character of the top section. The AK-4/5/6 gets away with it because of very steep slope.

Were you using a big choke on the mirange for using that tweeter that low?? Too much overlap from the natural rolloff of a K-55 otherwise, especially the one without the solder lugs. In the case of the lower Xover point to the tweeter, the DE-10 would be a better choice as would be the Faital Drivers.

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