PAP Trio 15 and DIY - Discussion

It has been a while since I last posted in this thread - most of the experimentation was put on hold as it was a huge PIA to rig up multiple power amps to try and tweak the crossover points as the calculated crossover didn't work particularly well.



I pulled the RAAL tweeters out and returned them to the monitors which now still collect dust



but I added in the vintage horn tweeters I picked up from someone local

I also decided it was time to embrace some pro gear to help the tweaking phase and added the following bits to the inventory

The Behringer Ultradrive Pro ( stock images )



and a compact amp to keep the simplicity of tweaking : The Crown CP 660 - only bought one, which gives me six channels with a whole lot of flexibility ( web images for purpose of posting )



this allows for relatively simple crossover configurations and adjustable levels at the amp level as well as through the crossover.

sadly had this all set up to test last weekend when I fell off a ladder and dislocated my knee - not been up to any lifting never mind these heavy beasts. When time comes, I will be testing various combinations of midrange units and bass units.

..dB

 

Back a few pages in this thread there was some experimenting with the Eminence Beta that seemed to have some good results. Eminence Alpha has been used in some open baffle projects, but is not really ideal.

 

The “classic” 15” OB driver is the eminence alpha, It has a higher q than other eminence 15”, and that lends itself to OB. It does have a weaker motor and more limited excursion than the neo’s from PAP. It’s inexpensive too.

higher performance? Acoustic Elegance dipole woofers are designed specifically for OB and come in 10”,12”,15” and 18”. The 15” has 15mm xmax (!!!). They claim operation to 2khz. $459 each though.

There are many other options here.

 

Yesterday I discovered that suspending my fullrange baffles with wide bungee cords that you normally use atop your car...completely removes any bass driver vibrations coming from the mounting frame, even at very high volumes.

You never know what direction experiments might take you. Have yet to figure out how this might be best exploited. When and if I do I will post pix.



I will post pix and measurements of my results I’m guessing in about 2 weeks.

 

For those with the two piece metal frame on trio 15...I discovered yesterday that inserting a small wood block to apply pressure between the woofer magnet and the back spine of the frame reduced frame and overall bass vibration significantly.

 

As i have been researching more into open baffle with the intention of owning a set soon and just working through exactly what i should buy as a one off purchase. So far it seems that the Voxativ 1.6 driver is much superior to the TB W8 and Dayton PS220. There were mentions of the Lii Crystal 10 which is getting good reviews and that Leonidas had created a crossover for. Wondering if anyone here have tried the Crystal 10 in place of the Voxativ? it would be a great saving $ wise from the Voxativ.

 

I have heard others praise Alpair drivers as well. (The 10p model is the one I’ve seen most used in discussion forums). It isn’t expensive.

I do expect the voxativ would be best piston driver choice, but wonder if, for the money, a quality ribbon or AMT might be better?

 

I've only ever heard the Heil AMT optioned Trio 15. I like it quite a bit but will eventually try the TB or possibly something from Audio Nirvana. As mentioned before, The Heil is the oddball of the group and can't use the Leonidas Xover. So eventually I'll probably build or buy a Leonidas.

I spoke to Thomas from PAP last week. They tried a few of the Audio Nirvana drivers but prefer the Tang Band over them. I've got the itch to try a pair of Audio Nirvanas in a different box speaker just to play with single drivers. If I have a pair in house, i'll probably try them in the PAP anyway for the heck of it.

 

I’m getting close on the tangband with its magnet mount. Yesterday I created a front to back board across the top mount position upon which the magnet mount tangband sits. That board can be suspended with elastic members (will try that today) so it is vibration isolated. Already bass vibrations on fullrange are greatly reduced...and the fullrange baffle isn’t loaded with fullrange energy. The new FR baffle is only about 11” wide at front, with 20 degree wings backwards.

image is much improved.

will post photos once I’m happy with it.

 

I tried yesterday reinstalling the passive crossover that came with my trios, and measured phase. It diverges from zero by about 90 degrees max.

I tried applying FIR filters to eliminate even that 90 degree phase shift. Discovered that FIR can 100% align phase to zero up to about 6 kHz, and after that the tangband phase disruptions can’t be controlled with FIR filters.

I think that says you can’t expect full fidelity above 6 kHz with the tangband, and it implies crossing to a quality tweeter will help imaging.

 

This may be a silly question, wouldnt flush mounting the full range driver will result in smoorth upper frequency?

 

I agree it does...any discontinuity from flush will create early reflections you will hear. So I cover the baffle with felt to make the path from cone to baffle edge as smooth as possible.

what I have recently observed is that when I try to adjust Tangband fullrange phase response above about 6khz or so (using FIR filters) I cannot achieve precision. That tells me the fullrange isn’t under full control above 6 kHz, and likely the listening experience would be improved with a real tweeter.

so I tried that yesterday, using a 1970’s 1” titanium dome pulled from an old pair of Canton Fonum 200 bookshelf speakers. Crossed that in at 2500 hz, 24 dB/octave and yes, there is more upper end detail now.

https://photos.app.goo.gl/vMsM5ZKA2BDvr5w79

using the Tangband over full range sounds great...swapping in a real tweeter to replace its top end does make a noticeable improvement, both in perceived detail and dramatically improved dispersion.

 

Pure Audio Project has announced the ' Trio15 Coax10" ', looks like its now a three-way with a 10" coaxial mid / tweeter replacing the center panel driver. There's an upgrade price available for current owners.

http://shop.pureaudioproject.com/product/trio15-coaxial-open-baffle-speakers/

 

Looks quite interesting! Wonder how it sounds.

 

I wonder how a Tannoy dual concentric coax would sound in that position?

 

The biggest issue I had with the Trio 15 was the laser-like focus of the treble from that middle driver. If it wasn't aimed just right both horizontally and vertically it was weird, and if it was exactly dialed in the treble got a bit hot.

I suspect the Tannoys would retain some of that but I think it could only be an improvement.

 

Do you think positioning it at the top would ameliorate this?

 

I did a mini write up on that earlier in this thread. It created a suck-out in the mids and the treble becoming even more prominent.

 

From my experience it seems many high efficiency wideband drivers have narrower directivity in the treble. Many circular horn tweeters too. I think this is the trade off for their higher efficiency

 

So this might be an argument for the Heil AMT. It takes a more complicated Xover than the standard Leonidas, but I never noticed any ultra narrow directivity with it. Horizontally It seems to be more forgiving than Maggies with a ribbon or quasi-ribbon tweeter. Or Klipsch Heritage models for that matter. Maybe that's not saying much. I had contemplated trying out the Tang Bands but maybe they're not for me.

I also can't hear much above 13-14k, so I can't comment on if the Heils are wrong for the overtly sizzle sensitive. My only other reference is that my buddy (of the same vintage as I and similar deafness) never thought they sounded hot either.

I can also concur that tweet on top sounds...strange. My old audiofool biases tell me that the mid placed tweeter should come up a few inches, but the listening confirms that it sounds about the same even when you sit up straight or slouch down a few inches. But again this is with the Heil.