Axiom Home Page Forums General Discussion Technical Questions HELP! Need Ammunition.

Recently, in two different threads about Axioms over at AVS, one vociferous poster has attacked Axiom based on his perceived discrepancy between the stated frequency response on the Axiom website and the accompanying graphs for the M22s, M60s, and M80s. I hesitated to post this, because I didn't want it to seem I was inviting people over to AVS to join in the unpleasantness. But both threads were eventually, and mercifully, locked by the moderators.

Here is one of his posts:

"So according to those graphs, as I read them:
m22ti are +/- 3dB from 77Hz to 18kHz
m60ti are +/- 3dB from 65Hz to 17.5KHz (or +/- 4dB from 37.5 to 18.5k depending on how you want to see it)
m80ti are +/- 3.5dB (I'm generous!) from 55hz to 17.5hz

Axiom's specifications (on their webpage):
m22ti: Freq Resp +/-3dB: 60 - 22kHz
m60ti: Freq Resp +/-3dB: 37 - 22kHz
m80ti: Freq Resp +/-3dB: 34 - 22kHz

no one explained that to me yet Axiom has the graphs on their webpage (graph link right next to their FR specs). Can they not read their own graphs?! I still don't get that, either I'm reading the graphs wrong, or Axiom is publishing false information...

Its very large differences... lower extension: 17 Hz for m22ti, 25+ hz for m60 and ~20 hz for m80... Highs, off by 4000Hz, as they all drop at around 17500Hz and not 22000Hz like spec'd by Axiom...

They don't say 'non-anechoic', but even if it did, it doesn't seem to hold up since I can't see a room which wouldn't mess up the +/- 3dB, & increase highs & lower extension..."

And from a later post:

'Just as a consumer, I don't enjoy being lied to... I believe that if you say your product does X and Y, it should do X and Y...."

It pains me to see a company I respect, and people I respect and like, being characterized as "liars" who are "publishing false information." I don't have enough technical expertise, or know enough about reading graphs to confirm or deny the person's assessments. So, I'd be grateful for any ammunition you can provide so the next time this comes up, and I suspect it WILL come up again (he seems to have made it his personal crusade to save the world from the evil Axiom empire) I can respond to him with cold hard facts.


M22 Freq Resp +/-3dB: 60 - 22kHz


M60 Freq Resp +/-3dB (Hz): 37 - 22kHz


M80 Freq Resp +/-3dB (Hz): 34 - 22kHz

I have been there and seen that post. I have actually read many posts there of people bashing Axioms without even listening to them. I have posted there several times in defence, but don't have the specific knowledge to deal with those graphs.

I think that is the same guy that Craigsub has battled against on many occasions in defense of Axiom. I believe he is using old charts.

Maybe we should all go on there and show him who the boss is

In reply to:

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Maybe we should all go on there and show him who the boss is

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No, that's what I want to avoid. The only way to win with guys like him is to refute his arguments with facts, not personal attacks.

Indeed, his usual opening gambit is the posting of links to the out of date graphs available on SoundstageAV.com. But his above posts are in reference to the current graphs I posted.

Actually, one never really wins with these guys. It can only be hoped that their agenda is transparent to the casual reader. The Pyrrhic victory comes in being sure that those casual readers, the ones who are just looking for some honest information, get exactly that; honest information.

And, yes, it's the same few guys that we have done battle with over and over again. It is, really, a waste of time. But, Craig is right. As his signature over at AVS says "All it will take for trolls to own the boards is for reasonable people to do nothing."

Ajax,

Inevitably this is the problem with posting graphs and why I really do not like doing it. Understanding how a speaker will perform and establishing its specifications requires interpreting a family of curves (amongst many other measurements and tests). In the case of the graphs in question here there are two issues that require further information than these graphs provide and one problem with this posters interpretation of the decibel spread. These are the standard on axis amplitude response graphs measured in the anechoic chamber at the NRC in Ottawa and represent what would arguably be the most important and most common measurements of a speaker’s performance. Below are the three issues:

1) Since the anechoic chamber at the NRC is rated to be accurate to 85 Hz we also look at measurements done in free space to figure out the true response of the speaker below this frequency. There is a correction curve written for the chamber at the NRC below 85 Hz and it does work fairly well (it is incorporated into these graphs) but not to the point of being able to rely on it within a few db.
2) Multiple microphone positions within a narrow range, which we refer to as the listening window, will also create small changes in the response including some fairly high Q changes above 14 kHz. These sorts of changes need to be interpolated to eliminate anomalies that are not part of the actual listening experience and to decide on the specifications.
3) +/- 3 db means 6 db from the highest point on the curve to the lowest point on the curve. This would mean that since the highest point on both the M22 and M60 curves is 90 db the lowest allowable point would be 84 db. This would be 70 Hz on the M22 and 40 Hz on the M60.

In the case of the M80 I would come up with 55 Hz also within a spread of 86 db to 92 db. And here we have an excellent example of why the family of curves is so important when figuring out how a speaker will actually perform and establishing its specifications. As I am sure many on this board have experienced first hand, the M80 has more and deeper bass than the M60 (a quick listen test will show that clearly), but if we only look at these graphs then our specifications would have the M60 going down to 40 Hz and the M80 only going down to 55 Hz. Specifications that most closely represent the performance of the speaker cannot be built on a single graph.

Another reason why i have pretty much given up on the audio section of avsforum. I find this forum and audioholics much better for all around advice and opinions. Too many jerks on avsforum. A shame too because there are some really nice and helpful people there if you can find them.

Interesting this topic should arise. I found a similar thread 2 days ago on Audioholics. Link Gene at Audioholics added some clarifing information to the thread that you might find informative. ...Oh, never mind, Ian posted more useful information.

While the discrepency between test condition results and real world is interesting, I found the discussion just a little too technical for me to feel like digging into. Specifications aren't everything. I'd swear my M22's provide more base than the Energy C-3's I was using even though the published specifications are the opposite. However, I have yet to run direct comparison tests to verify my first impressions.

On the treble side, I found something interesting with the Energy C3. The "listening window" curve for the C3 was reasonably flat up to 20 KHz while the corresponding curve for the Axioms dropped a fair amount between 15 and 20. The listening window is several curves averaged together so I took a look at the individual curves. Aha -- the C3 spikes UP fairly sharply between 15 and 20 KHz on axis, is flat slightly off axis and rolls off sharply further off axis. The result is a flat curve when you average together at the cost of pumped up high treble when listening on axis (which IMO is what matters).

Thank you, Ian, for taking the time to clarify things. Unfortunately, playing devil's advocate for a moment, all this guy is gonna see is that, in his opinion, the graph doesn't match the published specs. Whenever the Axiom name pops up in a thread he will continue to attack and point out speakers, like the Ascend CBM 170, whose graph confirms their published specs. Interestingly, I find the Ascend graph considerably more confusing than any Axiom graph due to the weird vertical dB scale.

Ascend CBM 170 Frequency Response (Anechoic) 69Hz - 20kHz +/- 3dB



Perhaps it would be worthwhile to clearly differentiate between an anechoic frequency response graph, and in-room, or other, frequency response specs.

Montclair, thanks for posting that link. I can't get over the difference between the civilized Audioholics thread, and the vicious AVS thread. Reading Gene's comments sure helped.

After that thread got locked, I decided to do some more investigation myself, and pretty much got the same explination that Ian gave. Unfortunatly, if I post it, it will create another bad thread because I have no hard evidence.

I will have to disagree with Jack, he just used Axoim as an example, also, the thread was about Axiom. When you get in to a defense mode(a bad mode to be in especially when you are defending) you tend to think it is all about you.

As I see it, just like Jack's example of using Ascend(that is Ascend's own published graph although the Soundstage graph is similar), Soundstage and the NRC need to publish measuring anomalies and, IMO, comparison to spec and reasons for discrepency. Otherwise, the issue will never be put to rest.