So far I've found it hard to duplicate my active XO's as well. I've gone through a couple of iterations to try to match the sound of the active XO but still come up a bit short. I haven't been able to actually measure the speakers with the active XO yet, only the passive. I'm hoping to do some measurements soon to compare the active and passive XO's directly to figure out why they sound different.
the HM170Z18 is one of Audax's aerogel drivers. I think it's some kind of mix of plastic and carbon fiber. It seemed to disappear when Audax bowed out of the DIY market but I noticed they showed up at Madisound again recently:
Audax HM170Z18 6.5" Aerogel Cone from Madisound
For the most part it is fairly flat. The first iteration was passive and I targeted 4th order LR slopes at 2kHz based on 1m on axis measurements. It measured well on axis but sounded bad, kind of tinny and gave the impression of too much high midrange/low treble. At some point I tried active equalization and inserted something like a BBC dip. Things sounded much better. After taking measurements off axis and playing with XO's in Allocator, the issue seemed to be that the directivity of the Audax started narrowing around 2k compared to the tweeters. This caused a bit of hole off axis at the crossover frequency followed by a hump around 3-4 kHz where the tweeter had wide dispersion. Reducing the output of the tweeter in the 3kHz range gave the dip on axis but smoothed things out off axis. At some point in this process I noticed that some female vocals and trumpet had a slightly forward and fatiguing sound. Other speakers I had on hand, namely the Paradigm Atoms, didn't have this quality despite sounding much brighter in the treble. Unintuitively, I found that increasing the tweeter level did make female vocals less fatiguing at the expense of an overall natural tonal balance. I've read comments here about the HM170 that are similar to my impressions so I suspect it may be the culprit. However, I can't be sure it's not some kind of power response issue mating a 6" woofer to a 1" tweeter. I'm experimenting with lower XO points to see if I can get a smoother on/off axis balance. The next step in the process will probably we to go 3 way with a 4" driver or a 2" dome for the mids.
I agree, however the hard part is that different people can have very different subjective impressions, and one's own subjective impression can be different at different times. Compared to StigErik, I feel the bass of the HD580's is the one spot that is slightly overemphasized. Their treble does not sound rolled off to me, but very extended and natural. Maybe we have different references or tastes, but it shows that sometimes listening for yourself is the only way to determine how something sounds subjectively. No matter how many reviews you have access to to help understand how a speaker sounds, you might end up with a totally different impression when you hear it.
Dan
Get an equalizer and set it to this?
An externally hosted image should be here but it was not working when we last tested it.
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