Vifa XT25 and 2 x P13WH-00-08 project

[fury]

Well i've just aquired 6 x P13WH-00-08's, and I already have 2 x XT25's left over from my car (need another obviously).

My front speakers are currently in the process of being built (Dyn/Morel drivers), but i'm now wanting to create rear and center channels with the above drivers, so I can get them painted at the same time (for consistency).

So anyway, i'm wondering if there are any projects that use the above drivers, or if anyone has a good box or crossover design for them?

I'm thinking a sealed MTM design, so that they all look the same (with the center lying on its side). I understand bass extension will be lost (as they are only 5" drivers), but it will help keep the enclosure small. (note: i havent modeled these yet, just getting ideas first, but i've read they suit 6ltrs sealed).

Cheers

[JC Fardo]

Try to trade the xo schematics with the designer

John Eekels ME2

Good luck

[JC Fardo]

Or you may consider a pair of MT´s for surounds

SDS Okara

[clm811]

Just noticed the thread...

In 2002 I was looking for a replacement tweeter for my ME-2 louspeakers (my kids had pushed in the domes of the D29's, plus the sticky coating had accumulated a lot of dust and fuzz).

I came across the XT25 at Speaker City USA, and it looked interesting. Other than the 4ohm impedance, the specs looked about right for use with the Ariel crossover; However, using the original crossover for the Ariel/ME-2, it didn't sound quite right.

Thanks to Jonmarsh, I tried a conjugate network and it seemed to help. Several crossovers tried were 2nd & 3rd order B'worth as well as a few unconventional topologies; Naturally, some worked better than others. Listening comparisons narrowed the choices down to three nice-sounding contenders:
1. 2nd order* symmetrical B'worth;
2. 3rd order* symmetrical B'worth;
3. Asymmetrical 1st order* L.P. + 2nd order* H.P.(mod of Ariel)
* electrical (vs acoustic)

In 2004 I was fortunate to meet with members of the Northern California DIY club http://www.ncdiyaudio.com/, and attended a meeting for loudspeaker listening and measurements. It was great fun and thanks to Mark K I now had measurements for my MTM's with three crossovers. It happened that the flattest amplitude response was obtained with the symmetrical 3rd order Butterworth at 3kHz. There were a few small ripples in the highpass that I couldn't account for, since they were above the crossover and were not part of the drivers' responses. These were later determined to be due to diffraction effects.

Four years later I'm still enjoying these speakers, of which I've built several pairs, experimenting with various panel damping and baffle configurations.

Attached is a photo of the latest version I'm using for the front R+L channels of a multichannel audio system.

Any questions or commments are welcomed.

-chas

[jtsaudio]

Nice looking cabinets; Interesting baffle shape!
What kind of wood are they made from?

-JT

[gainphile]

The Aethers

http://undefinition.googlepages.com/diy-aethers

[clm811]

Nice looking cabinets; What kind of wood are they made from?

Started with the commercially-made MTM cabinets of 0.75" MDF , enlarging holes to fit my drivers;

Then added additional bracing and then damped the cabinet walls with a layer of Soundcoat and attached convoluted foam to enclosure walls;

Installed compact port tubes (90 degree PVC pipe elbows), inserted trimmed port tubes in each end and filled gaps with clay-like material, then attached radiused port ends. These worked well, but the response ripples due to diffraction still needed addressing;

Subsequently, I made dams from layers of tape and cast a mixture of polyester resin and limestone powder 0.5" thick onto baffle for a final thickness of 1.25". Molded and then sanded to desired contour. Enclosures were then painted matte black.

Finally, 0.75" solid oak "cheeks" were attached with cabinet bolts.

A lot of work, but it paid off with very well damped (and heavy)enclosures with flush mounted drivers and minimal diffraction.

-chas

[clm811]

Reviewing old back issues of Speaker Builder and AudioXpress, I noticed an article on diffraction (ACOUSTIC DIFFRACTION: DOES IT MATTER? by James Moriyasu). He had performed several tests & measurements using a midbass and a tweeter on a flat IEC baffle as well as other shaped baffles, and documented results.

After experimenting, I settled on an asymmetrical combination of a 2”radius on one side coupled with a dual chamfer (22 degrees, transitioning to 45degrees) across 2". Together with the existing driver offset, this yielded a smoother response from my drivers and enclosures. The right and left channel baffles are mirror-imaged.


Here's a close-up of the baffle profile from above:

[fury]

Very nice work!

Glad to see people still experimenting with these.
I put my project on hold currently, but have a pair of these running in my car and am very happy with the sound in a less ideal environment