I just finished reading the whole thread (took almost 2 hours and I read pretty fast) and didn't learn anything past about the 10th page. The executive summary is :
- Craig and Ilkka both did excellent reviews; Craig focused more on listening tests while Ilkka focused more on measurements
- They came to somewhat different conclusions. The main issue was THD; Ilkka's THD numbers on the 600 were suspiciously high, to the point where many suspected a problem with the measurements. Ilkka concluded the problem was "Axiom's wimpy driver", which seems both premature and probably wrong to me
- many pages of vitriol, including accusations that both Craig and Ilkka had falsified their measurements to let their favorite vendor win. To me, this seems insane and childish to boot; both are doing this as a hobby; neither would even consider fudging the numbers to affect the outcome
- several pages of confusion between "Axiom confirmed that the EP600 was typical" and "Axiom agrees with all my measurements" resulting in nearly everyone being pissed off
- it does seem possible that the spiffy DSP firmware in the 500/600 is kicking in on test tones (but not on real movie/music content) and mucking up the results. Axiom has revised the firmware at least once to fine-tune the limiter code which some interpreted as an improvement and others claimed were a clear sign that Axiom was shipping defective product. Not worthy of comment unless you think Axiom is the only company to ever release a firmware upgrade
- there has apparently been a slight change in the port characteristics on the 600. Details are conflicting -- seems to involve lowering the tune point a few Hz, which presumably might require a corresponding update in the DSP firmware
- a couple of EP600 owners piped in, including at least one owner ("jakeman") who also owns an SVS Ultra. Jakeman contacted Axiom to get more info and ended up visiting (he lives pretty close to them) which inflamed the avsforum people even more
- decision to organize an impartial test at NRC, presumably initiated by Craig (I'm guessing here), with invitations sent to both Axiom and SVS in case they want to participate directly
- another round of muck-raking, to the point where now people are questioning whether the NRC would be impartial because Ian used to be involved with their research (as were the technical leads of Paradigm, PSB and Energy)
- a couple of suggestions that a fist-fight between Craig and Ilkka might settle things
- a side discussion on body fat % that I still don't fully understand
Anyways, hopefully this will all settle down. After reading 23 pages of posts my personal impressions haven't changed at all, being :
- if you ripped out the DSP from the EP600 and just compared hardware, the Ultra would probably outperform the 600 by a small margin in terms of maximum clean SPL around 20 Hz. Since Ilkka's tests focused on single tones, his conclusions leaned the same way. Even so, his THD readings (>10 % at pretty much all frequencies and SPLs) seem suspect. There was some discussion that background noise (wind ?) might have been a factor.
- playing real content, the 600 seems to be a stellar performer and multiple people have indicated that it seems to outperform an Ultra in many listening tests, giving the perception of more headroom and more useful output over the Ultra
Which is better ? No easy answer there.
