ZD5 impedance curve mismatch

[zdr]

I've just setup my measurement jig for LIMP, so I gave it a go on ZD5. What came out is a huge mismatch in bottom end impedance curve. Could stuffing be causing this, since I double checked the crossover and imaging is spot on?

 

[Flaesh]

.. Could stuffing be causing this,..

(yellow curve with more mechanical loss)

 

[zdr]

Hm, should I be bothered with this? I managed to align the peaks by adding more stuffing into the box that was missing it, and now they are both the same inside out. Peaks are still much higher on one than on the other.

 

[zdr]

Erm, yes I should. There is audible difference between the two. The higher peak sounds brighter, pulling the image to the side. I just wonder what could be the problem... I am tripplechecking the stuffing and mechanics.

 

[Flaesh]

are drivers themself (w\o enclosure) identical?
are speakers w\o stuffing identical?

 

[sreten]

Hi, test the raw bass/mid drivers in free air, rgds, sreten.

 

[zdr]

Yep, just did, and switched drivers. Problem stays with the box... Stuffing is approximately the same, I will make it identical tomorrow.

 

[zdr]

Huh, I am really scratching my head on this one. Boxes and stuffing are now identical, and I still have a peak height mismatch. I even scalloped some more around the driver.

The one with higher peak definitely sounds more open and detailed. I am about to redo the crossover so that I can switch them between the boxes, to narrow down to box or crossover.

I don't know if it makes sense to switch XT25s...

 

[Flaesh]

can you definetly eliminate any leakage? gap between panels??

 

[zdr]

Yep, that was it. I made a test with rear panels removed, and curves aligned. It was a gap between removable rear panel and the box, caused by tiny dry paint drops.

 

[Flaesh]

ok!
and what about my http://www.diyaudio.com/forums/multi-way/173821-nonidentity-two-compression-drivers.html question?