craigsub said:
Ilkka, Until you actually make blind testing a part of your subwoofer tests, you are running half a test.
This is going way OT, but I'll answer to these questions.
Yes, I agree that blind listening (or even open listening) would add more info to my measurements, but unfortunately it's just not possible. You can not compare my "shootouts" to for example Ed Mullen's subwoofers reviews. They are totally different. Yes, we take almost exactly same measurements, but Ed does it only for a single subwoofer at a time, I prefer to measure as many subwoofers as possible. First time I measured eight different subs/different tunings, all in around 5-6 hours. I have lined up around 12 subs for my next session and I'm planning to measure them in less than 6 hours. It is just impossible that I could listen to all of those subs in my own room. Or even outside like Yates did, I just don't have enough time for that. I have already tested my own subs, so all the upcoming subs will belong to my friends or forum members, who will be driving them to my measurement session. I can't just take their subs and keep them in my room (also space is one issue) for several weeks, which proper listening would require. I don't also get paid for doing this (for example like Ed or Yates), so I'm not willing to do that amount of free work, which proper listening would require. At least here in Finland most of the forums members where I have posted the results, have been very surprised how I even do this amount of free work. They understand that listening them is just literally impossible. But don't get me wrong, if someone wants to give me the subs and pay a reasonable amount of money, I will gladly do a similar test like Yates did, it would be very fun and instructive.
Same thing with AV Talk. They just CAN'T add any listening tests, since most of the subs belong to the fellow forum members.
You also set abritrary test parameters which favor SVS. For example, you decided to use this "10 % THD + N" for your max output charts ..
Yet, in comression tests, the EP-600 delivered 99 dB @ 20 Hz ... Someone looking at this chart would think the EP-600 to be a poor performer. You KNEW this when you posted that chart.
I originally choose the <10% THD+N test because both Tom Noussaine and Ed Mullen are using it. I didn't know if it would favour SVS or any other brand. It was also chosen because I (or anyone else using TrueRTA) didn't know how to take THD sweeps. I completely agree that <10% THD+N tests doesn't tell the whole truth about subwoofer's performance and that's why I also used the other kind of test to measured THD levels, especially at lower levels, because we don't always listen to your subs at max or near 10% THD level. But the program I used for these "poor man sweep tests" turned out to deliver skewed results, if one would adjust the output level from the wrong place. This happened with Axiom (I take the full responsibility of this error, but it was VERY cold out there and I hurried..and made an error). I also made the error that I posted that graph (which I later deleted), which I shouldn't have done. I didn't look at it so carefully when posting it, but when you pointed out the errors, I knew it couldn't represent its true performance.
You should also know that I won't be using the <10% THD test anymore in my future measurements. We have developed a new test and it will show subwoofer's THD level at all measured levels and frequencies, from bottom to top. Just wait for the new shootout results, I think you will like them very much. And since EP-600's "THD sweeps" results were skewed, I will be measuring it again using these new tests we have developed. Also there will be much more subs to be tested at the same time than SVS PB10.
I, along with several dozen other people (including Bossobass, who knows a few things about subwoofers) in our home, AND every other reviewer who has experienced the EP-600 has raved about its performance. At NO time is distortion audible with the EP-600.
I don't believe EP-600's distortion can be heard when using program material. I have only measured the numbers using sine waves, but never claimed it would have audible THD when using program material. I have claimed that one can separate a 10% THD at 20 Hz from 1% THD and I stand behind that statement.
And yet, Ilkka, I have seen several e-mails in which you told people about it having "cone cry, farting ... etc ..."
That is impossible with the EP-600. The DSP will not allow that to happen.
Maybe you don't remember this, but I explained this to you over at AVS in a PM discussion we had around a month ago. When I got the EP-600, I had some difficulties in achieving a flat in-room FR. I tried the same place where for example Ultra produces a quite flat response, but still I couldn't get a good response. Then I thought it must be related to EP-600's front firing configuration and therefore I placed some books under its each end and used it as a downfiring sub. Surprisingly FR was better, but the performance was lacking badly. Of course I couldn't tell this by then. I ran many tests between it and the Ultra, using the same TrueRTA "peak hold" method as you use, and of course was listening at the same time. During those tests I heard cone cry, farting and the performance was clearly lacking. There was a good 2-3" distance between the driver/port and floor, but apparently this wasn't enough or maybe the DSP didn't like the downfiring configuration. After those tests I wrote that ONE e-mail to Jakeman, who was at the time still my friend, where I wrongly blaimed it for bad performance, when it actually was caused by me. After those tests I found out a really good spot for it (corner) and was surprised of its enhanced performance. I also wrote a correction mail to John, but you probably never saw that one. I haven't heard any additional noises from it since.
The EP-600 will deliver, @ 20 Hz, a 99 dB signal @ 2 meters ground plane with no audible distortion. The 86 db you list in the chart is totally mis-leading.
I can not change the "rules" for every sub I test. I chose the 10% THD test and of course every sub was measured using same criteria. But as I said, there will be new tests and you won't see those 10% numbers any more in the future. It is okay for us to develop and make our tests and measurements better?
The comparison tables using the data from 10% THD tests were made for you all. They were made to help comparing the clean output of tested subwoofers, but as I said, 10% THD doesn't necessarily represent the "clean" output limit especially at lower frequencies.
You also still have this diatribe in your review ...
You cannot do a listening evaluation with the EP-600 ?
I have tried to replicate the problem you had with the Avia disc, TrueRTA, Emotiva Test Tones ... etc ... it is no harder to calibrate than any other subwoofer.
It's not hard to calibrate it, if the output level is high enough. It's the gain which doesn't stay linear. Like I said in my review, subwoofer's output jumps suddenly ~10 dB at a certain output level, which is around 80 dB in my room. And it doesn't depend on subwoofer's gain setting or receiver's sub output level. Ian Colquhoun explained to me that EP-600 has this kind of function, with it tries to bring the noise level lower. Unfortunately it also affects on test signals and music signals too, at least with my EP-600. If you have a larger room, meaning you will have to calibrate it to a higher level (above this jump level), one could easily miss this behaviour.
Finally ... you promised, in writing, to send the subwoofer back to Axiom. That promise is still in your review.
Yes I did. I said it because I suspected that there might be something wrong in my unit. But since then I have heard at least two other units having this same odd behaviour, so I'm thinking it is perfectly normal. I don't see why I would need to send a working sub back? It just doesn't work well in my small room and with strong room gain it has. I am going to sell this unit soon, so maybe the next owner has a better luck with it. If not, he can probably contact to Axiom and see if they can think a fix. I have been humiliated and accused of having bias and God knows what else by Axiom, so I don't want to have any kind of businesses with them anymore.
