PAP Trio 15 and DIY - Discussion

TWO gigantic toroids. Jantzen is his sponsor. They don't pay him anything, but he gets XO parts for free.

 

It looks like the goal was to live with -3dB @ 50Hz and get agile bass in return.
He has expressed dislike towards high Qts drivers, even for OB.

 

I'm glad you mentioned this Faital driver. Just yesterday my buddy said to take a look at it after a discussion about the notch needed on the top end of the Neo15. The frequency response is a lot smoother than the Neo15 and had it worked, would have simplified the Xover a lot. Unfortunately, when I pulled up the specs, the Qts is about half of what is needed for an OB design.

I looked through about 3/4 of the 15s that Parts Express sells and found that a woofer with low Fs + high Xmax + Qts>.7 is a real rarity. I guess this is why PAP commissioned their own woofer, despite their imperfections.

 

What about the Hawthorne Audio 'Augie'? You can actually still get these new.

https://www.amazon.com/gp/offer-listing/B01C7HVG1A/ref=dp_olp_0?ie=UTF8&condition=all

They are selling them until they deplete their stock. I have no idea how this is in a WTW configuration though. But I've seen plenty of builds where the baffle is as narrow as a PAP.

According to AMZN specs

Fs: 27Hz
Xmax: 7mm
Qt: 0.92

 

I couldn't find a frequency plot on those to see if they're any better than the NEO15s. One website said they're only 88dB efficient which is a significant drop over the NEO15s being in the mid 90's that's kind of a deal breaker to me. The Augies are also more expensive.

 

Augie FR plots and review... http://www.enjoythemusic.com/magazine/equipment/0107/diy_loudspeaker_project.htm

 

From skem's link

Which based on this:

means you are looking for something that doesn't seem possible

 

Beyond Troels, it seems others have found low Qt woofers to be ok in OB implementations, in some cases beneficial, provided you can tame the FR. See reply 15 here.
https://www.audiocircle.com/index.php?topic=147509.msg1577937#msg1577937

 

The subs Linkwitz uses for his LX521 have a QT of 0.27. Of course he applies a lot of DSP too

 

You don’t want too high of a Qts on OB woofers. Perfect example: the Carver Amazing Loudspeaker from the 80-90s. It used these cheap shit woofers with dinky magnets to create a high Q to compensate for some of the dipole cancellation. Their bass was muddy and sloppy.

I recommend 0.5 - 0.7 from my experience.

 

@ultrabike I derped. I thought the time-delay from the woofer would be enough to screw up the FR in the crossover region even with 2nd order filters. After you banned me last Monday I ran a quick simulation and realized that this was most likely not the case. Again, all of this was based on my experience with the first order slopes (which I knew this was not) and my own measurements of the acoustic centers of the drivers that I have here. I assumed there would be a Z-axis offset of about 4 inches which I thought you hadn't put in your models.

Anyway, thanks for providing your files. I might try to model it in PSD-lite, too.

That's just the difference between 120mm Z-offset and no offset for the first order slopes at around 360Hz. The widebander has some excess phase because of the whizzer cone which is why the null is particularly bad in this case afaik. IME the null really is that bad when putting both drivers on the same baffle without any offset. The crossover would have to be totally different for the PAP design than for my baffles.

@crazychile, I had no idea the crossover was that expensive. I wouldn't have suggested that you should simply buy the original crossover, especially when I'm highly sceptical of the Leonidas crossover in the PAP speakers with widebanders. The ESS AMT one less so since the measurements I've seen looked better than those of the PAP. I forgot where I found them and they're not the most accurate, but they are available publicly somewhere. Or maybe I confused them with some other PAP speaker.

Sorry folks, I misread the first post because I was tired and I have a bad habit of sometimes getting really salty when someone else gets angry with me. I'll try not to post late at night again. Lots of noise could've been avoided.

 

Problem with Alpha15 was tiny magnet. The high Q does fetch you more bass extension on paper. Sometimes less is more.

 

I played around with PSD-Lite for the first time last night. I imported the .frd and.zma files that @ultrabike provided for the Heil and PAP drivers a few pages back. Even when I put in the exact Xover component values, the summed response looked a lot different. The overall output was lower across the spectrum except it climbed up from the midbass down to the sub-100Hz region. When I opened up the T/S parameters screen they looked way off from what PAP provides for the woofers. I havent checked the T/S for the Heil yet.

I set the project up as a 3 way since there was no option for a 2.5 way. I also selected the open baffle option. I rearranged the drivers into a WTW configuration, but the graphics for the "midrange" had a box around it that I couldn't get rid of. I wasn't able to get the baffle size and driver displacement numbers entered in precisely yet.

If anyone has any idea as to what I'm doing wrong, I'm all ears.

Despite the issues, PSD-Lite is still pretty intuitive compared to the others I've tried.