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Re: EP-600 Review thread.
#109247 11/07/05 02:37 AM
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axiomite
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Let's start a "wave"...


M60ti, VP180, QS8, M2ti, EP500, PC-Plus 20-39
M5HP, M40ti, Sierra-1
LFR1100 active, ADA1500-4 and -8
Re: EP-600 Review thread.
#109248 11/07/05 02:55 AM
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You guys crack me up.

Re: EP-600 Review thread.
#109249 11/07/05 02:56 AM
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axiomite
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I loathe "the wave". It was invented by and for people who are disinclined to actually watch the game they paid to attend.

However, I do deeply appreciate Bridgeman's synopsis, Craigsub's candor and Jack's eloquence.

The Axiom forum remains my online home for these and many other reasons.

I loved the observation about numbers not telling the whole story. Has anybody looked at Dave Krieg's career stats?


bibere usque ad hilaritatem
Re: EP-600 Review thread.
#109250 11/07/05 03:31 AM
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I just want to know how what happened at the Axiom plant………when are those results going to be shared?

Re: EP-600 Review thread.
#109251 11/07/05 05:57 PM
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Ian Offline
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Thank you for the summary of the discussion at AVSForum. As you may have gathered, we have an issue with the test procedures used, which I brought up before these tests began. At the time, I was assured that these problems were going to be worked through together before any data went public; unfortunately that agreement and the opportunity to increase the accuracy and relevance of the results being tested were ignored after the subwoofer was shipped.

The two main problems with the procedure are the linearity accuracy and the relationship of THD & Noise to real world conditions. First for linearity; the frequency response measurement used by Ilkka, and quite a few others, utilizes a smoothing calculation. The problem with this is that products that are linear simply remain linear (and in fact may even be worsened by smoothing), by pulling down information at the crossover or filter points. The smoothed graph of the EP600, for example, shows a gentle sloping decline or roll-off at the filter points of 15Hz and 100Hz which does not appear in reality with precise measurements. Products that are not linear, however, are made linear by this technique. Linearity is a paramount indicator of the quality of the end performance and should never be modified by using smoothing, or a low number of data points, both of which will hide anomalies in frequency response.

The THD & Noise methodology used in the Finland test is to plot a graph of 7 points from 20 to 80 Hz at a max level of 10% THD. There are a number of problems with this. First, the general problem of noise occurring during the listening experience, such as woofer bottoming, happens below 20 Hz. So in order to relate such measurements as this to the listening experience two things need to be done: one is to establish at what level of THD & Noise the listener experience will be compromised, and two is to then apply this level to all frequencies. We use 100 data points between 150Hz and 10Hz to determine THD & Noise.

Once a level of volume is attained that has audible distortion - at any single frequency - that is your maximum SPL for all frequencies, because the distortion that occurred will intrude on the listening experience each time that frequency is produced. Obviously, listening to movies or music is a dynamic experience, and frequencies change constantly, so that volume is defacto the maximum logical usable SPL output. The method of plotting distortion at various frequencies, and then connecting those points like a response curve, is not a measurement that can be translated into any usable real world condition. For us at Axiom, we have determined through extensive listening tests that this level is when the THD & Noise exceeds the signal frequency. Neither the EP500 nor EP600 will allow the THD & Noise to exceed the signal level at any frequency no matter the volume level setting. If the tester decides that 10% THD & Noise is the level at which audible distortion will occur in the listening experience (our tests have never shown this to be the case), then this, at the very least, needs to be applied to all frequencies.

As you can see, this is a fascinating subject that has spawned numerous Audio Engineering Society papers and decades of research at the National Research Council (NRC). The real fun begins when you start to prove out each measured number utilizing scientifically controlled listening tests. I can hardly believe I have been doing this research for 25 years now but I look forward to continuing to discover more over the next 25 years.



Ian Colquhoun
President & Chief Engineer
Re: EP-600 Review thread.
#109252 11/07/05 06:47 PM
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axiomite
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Thanks so much for commenting, Ian. That Ilkka failed to honor his word is very disappointing. In my mind, this only confirms the belief that his goal was to disparage the EP600, rather than do an honest review. Hopefully, down the road, his irresponsible behavior will cause him more discomfort than it has you and Axiom.


Jack

"People generally quarrel because they cannot argue." - G. K. Chesterton
Re: EP-600 Review thread.
#109253 11/07/05 06:53 PM
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Ian, thank you very much for not only taking the time to share your observations and educate us, but also for doing so in such a gracious manner.

Two things to me are worth noting. First, that you have, in fact, been conducting this type of scientific research under controlled conditions for your entire professional career. Your sustained success and proven talent in loudspeaker design deserve corresponding respect. Such pursuits are extraordinarily complex, and extend well beyond the experience and expertise of a talented hobbyist with a microphone in a Finnish parking lot.

Second, I could not resist the opportunity to underscore
In reply to:

not a measurement that can be translated into any usable real world condition




This phrase again reminded me of the nugget attributed to Twain or Disraeli - "There are three kinds of lies: lies, damned lies and statistics". It has been proven repeatedly, in this discpline and in others, that numbers simply do not tell the entire story, and that methodology and motive ought to be considered by astute readers.

Try as we might to reduce music and its reproduction to numbers, it retains creative and artistic components that defy simple quantitative analysis. For me, the joy is in the listening, not in the testing. For the products that provide that ongoing joy in my life, and for the way you conduct your business, I thank you.


bibere usque ad hilaritatem
Re: EP-600 Review thread.
#109254 11/07/05 07:22 PM
Joined: Feb 2005
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axiomite
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In reply to:

This phrase again reminded me of the nugget attributed to Twain or Disraeli - "There are three kinds of lies: lies, damned lies and statistics". It has been proven repeatedly, in this discpline and in others, that numbers simply do not tell the entire story, and that methodology and motive ought to be considered by astute readers.

Try as we might to reduce music and its reproduction to numbers, it retains creative and artistic components that defy simple quantitative analysis. For me, the joy is in the listening, not in the testing. For the products that provide that ongoing joy in my life, and for the way you conduct your business, I thank you.



Very, very well said Tom!

In reply to:

For me, the joy is in the listening, not in the testing.



I couldn't agree more. Sometimes all it takes is a step back, a closure of the eyes along with a little imagination and these Axioms has a way of putting me into a completely different, and pleasant place.

Thanks Ian and your whole Axiom crew, you folks are great!


Rick
Our Room

smile
Re: EP-600 Review thread.
#109255 11/08/05 03:30 AM
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I have absolutely no idea what all you said means Ian, not a clue, but thanks! It sounds great!

I just hope it wasn't my inquiry that inspired you to put that much effort into a reply.

I was just curious to how the visit went with the other AVS fella at your factory. Jakeman??

If it means anything, I'm buying a 600.

Re: EP-600 Review thread.
#109256 11/08/05 03:56 AM
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C
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Ian has been great to work with during this whole process. There will come a time when I post a detailed enough response to everything that has transpired through this process. For now, it has been quite a learning experience. Ian's patience with me has been ... amazing.

Wonderful subwoofer, too.

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