Eclipse W520R-8/RS28F MTM

[johnnyrichards]

Not sure when I will get around to measurements - maybe tomorrow evening. 0.5 cubes, ~60Hz tune.

[Jim Holtz]

Very nice JR! I'm looking forward to hearing them at Iowa.

Jim

[meniscus]

Just be sure to connect both woofers.

[johnnyrichards]

Just be sure to connect both woofers.

[johnnyrichards]

As far as making it to Iowa, that remains to be seen. I only have the one pair and at the moment I lack the means to purchase a second pair to complete the other speaker. I will try and move some stuff via classifieds in order to procure the funds to get the other two drivers.

I will say this: so far, they are very impressive. They took considerably mechanical break-in (30 minutes at 60Hz@3mm), but afterwards have a very impressive quality to the midrange. I can see why Jeff was impressed at their performance in the Continuum environment.

Meniscus has another winner on their hands with this one - now if we can get Mark to design a 4-5" midbass designed for wideband use with highish sensitivity, say one that fits the same cutout as the CSS VWR126X..

[JasonP]

Meniscus has another winner on their hands with this one - now if we can get Mark to design a 4-5" midbass designed for wideband use with highish sensitivity, say one that fits the same cutout as the CSS VWR126X..

+1!

This is good to hear about the driver, I was excited when I first saw it on the table at InDIY. The world can always use another excellent small woofer IMO.

[johnnyrichards]

Well - the second pair is on the way, will ask forgiveness tomorrow lol!

These are pretty special little drivers, you guys.

[johnnyrichards]

Have a couple different options in the works - including one that crosses at 1100Hz. Monster crossover on that one, though - gets spendy pretty quickly. Still playing with tweeter levels and swapping a tweeter LCR comp in and out. I think it needs one at this Fc, but not yet 100% convinced.

Another option in the works is a five element design crossed around 2500. The low XO version has 11 - and some of them are pretty big value caps. I'll be spending some time with both iterations this weekend. Progress.

[johnnyrichards]

I ended up with a different XO than the one pictured above - similar XO point, shallower null but flatter through the that region.

These will be at IowaDIY in October if anyone is interested in listening to them. I will reiterate my early impressions of the driver, but add that the breakup proved to problematic in this application. Fortunately, the breakup doesn't propagate as odd order distortion to any meaningful level, so the issues I was presented with dealt more with destructive summation in the treble region.

Anywhoo, some pictures...

Finished system. Drivers are flush mounted, and construction details (along with details of the previous project inhabiting this) are found here: http://techtalk.parts-express.com/showt ... -named-MTM.



On axis with individual driver responses:



A little distortion action:



On-axis over impedance:



Some horizontals, it is my opinion that the way this changes off-axis demonstrates how important it is to A: take horizontal measurements, and B: don't over-obsess with "filling in the blanks" - in this case the so-called BBC dip going on there.



Assembled crossovers. Coils wound down to within 1/2% of spec and caps selected to meet spec in appropriate series/parallel wiring configuration. I used my DerEE LCR meter to do the measuring.



I tried three different padding resistors - I am personally using the 6 ohm resistor. Since the tweeter covers such a large range (cuts in around 1150), the small differences in padding values have a bigger than typical impact on overall tonal balance.



Coils are both 18awg, with the woofer using a laminated core. For illustrative purposes, I showed the 5.5 hooked up but as stated, I am using the 6 ohm option. The caps are all common enough values, as are the coils.



Cabinet is approximately 0.6 cubic feet, with final tuning in the very low 50's. Impedance curve indicates a so-called "optimally" flat tuning. I used Black Hole 5 all over inside it - expect to do serious experimentation if you use that product. It eats up a lot more internal space than one might think. Worth it for the benefits it brings. If doing a more traditional cabinet construction, all four of my woofers measured within 10% of advertised (actually closer) so I would consider using supplied T/S adequate for modeling purposes.

All-in, using Solen caps is just over $400 - not a cheap project and right smack in the middle of a lot of serious contenders. However, the $400 does offer a couple of advantages such as the increased output potential of a 4 ohm MTM, and the low XO point makes it less objectionable for horizontal center channel use.

Great job on this driver, guys - keep 'em coming!!!

[kenny_k]

Can't wait to hear them at Iowa.

[JasonP]

Looks great, will be awesome to hear these at Iowa!

[meniscus]

Johnny,

Do these have a name yet?

Mark

[johnnyrichards]

Hey Mark, still working out the details as far as a name. Will update soon.