On the break up issue of woofers. I will also note that when working with driver manufacturers on new drivers there have been times when the upper break up ranges are not acceptable. I am a bit of a stickler for that stuff. More upper level break up means more is needed in the way of the crossover to control it, and I hate that.
To solve this I often see the driver manufacturer use various methods to dampen the cone to control the break up. I have seen doping to the back side of the cone near the surround using various materials and in one case I had a driver manufacturer correct some break up present on an 8" woofer. I asked him what he did to correct it (because I expressed it as a problem and he made efforts to correct it that did correct some of it) and he said that he used a different type of adhesive to hold the surround on the cone. It was an adhesive that dried softer and not has hard as the adhesive that he used before.
So there are things that can be done to the cone to minimize break up effects and in some cases server ringing issues. Typically a brushed on damping material is added to the back side of the cone near the surround and is much thicker and heavier than the EnABL'd treatment.
The amount of material added to the EnABL'd drivers is not much more than what would be added by a magic marker. It is a really thin layer of material and not enough to add any real measured amount of mass that would be beyond normal tolerances of the moving mass itself. Also, what little there is added to the cone would certainly be more likely to have more of an effect on a smaller lighter weight cone than one as large as a 5.25" woofer.
Anyway, after seeing no real measured differences in the decay rates of the EnABL'd drivers I went on to listening comparisons.
My listening comparisons are a little different than Bud's. I set both woofers up in an enclosure with the woofers side by side. They are both hooked up to a high quality switching box to allow instant switching via spring loaded switch that is hand held from the listening seat. Identical speaker cable was used. The front end is a highly modded DAC 60 getting info from a CEC transport. I also use the Dodd battery power tube pre-amp that has gotten the killer reviews. I then used one of my mono-block tube amps also from Dodd Audio (yes the big blue monsters).
I would focus on a particular section of a piece of music (8 to 12 seconds at a time) and play it back about 6 or 8 times to really memorize every subtle detail. I then switched woofers and compared differences using the same process. This can go back and forth numbers times.
First I had to get past the full range playing woofer. The no tweeter top end isn't that bad, but the baffle step loss is a little harder to swallow. This leaves a little lack of body to the vocal range. There just isn't enough real weight. I don't know how anyone can stand to listen to those full range drivers without a compensation network. Never the less, it was not hard to make comparisons.
After many back and forth's, that even including swapping the inputs and swapping the two woofer locations to make sure placement had no effect (even though they were side by side), I began to reach some obvious conclusions.
The EnABL'd woofer sound like a fairly fresh woofer (little to no burn in). Vocals still had a slight edge or boxy sound to them and the piano had a little too much trailing edge ring to it compared to the other woofer.
The other woofer (the stock woofer) was one of the woofers that had been burned in for 48 hours. It clearly had a more relaxed vocal range and sound more transparent. The piano was cleaner and had less over ring to it as well. It had a smoother and more relaxed sound just as it should. It sounded just like a woofer than had some time on it.
I wondered if there might be any real difference between the EnABL'd woofer and a fresh out of the box woofer but not enough to go through this again with a fresh woofer. The EnABL'd woofer certainly didn't stand out as being better in any way, much less different from the norm, and the burned in woofer clearly sounded better.
If the EnABL'd woofer would have showed me any real differences running it full range then I would have tried the pair of EnABL'd woofers in one of my A/V-3 demo speakers and compared it side by side with the other A/V-3 speaker. But I felt that if I can't hear any differences running it full range I certainly wasn't going to hear any differences where the woofer was limited to playing no higher than 2.5kHz in range.
So I got ahold of Bud again and asked him how many hours of play time the woofers received during his listening. Much to my surprise, he said it was only about an hour. So there was good reason why the EnABL'd woofers sounded as if they had no time on them (like a fresh woofer), because they really didn't have much time on them.
In talking further with Bud, he suggested that I look at the off axis response measurements. He felt like the real difference would be in the off axis response.
I felt like that if the texture of the EnABL'd process was great enough to create some real ridges then it could have some effect in the off axis, but the height of the brushed on material was hardly thick enough to feel. So even the shortest wavelengths would pass by with no effect. Plus my woofer doesn't play up high enough to cover the shortest wavelengths of the top octaves. So I was pretty skeptical, but I tried it anyway.
I picked the EnABL'd woofer that had a response curve that nearly exactly matched one of the stock woofers and both stock woofers. I made off axis measurements at 20, 40, and 60 degrees off axis and saved spectral decays of each woofer. Bud suggested I go out to 90 degrees off axis, but that seemed a bit pointless as the further you go off axis the less the woofer covers the upper ranges. If the EnABL'd process were to show any differences at all then I felt it would show up in the top octave to began with.
To cut to the chase. I could see no real differences between the three woofers in the off axis responses that varied enough to make one really different. I did find that there were subtle differences between the three woofers but nothing more than standard tolerances. Another interesting note was that variations as little as 2 to 3 degrees off axis also made subtle changes to the spectral decay. So I really tried to make sure each response curve was dead on 20, 40, and 60 degrees off axis, but there was certainly a variance of a couple of degrees that had subtle effect on the measurements.
Again I raised the data to above the 0 line. So 0 is really -5db down already and -25db is really -30db down. This was to see what was below -25db down. Considering the driver to driver variances and a plus or minus 2 degrees (possible) variance in direction I really see nothing that stands out.
Another thing to consider in the off axis measurements is that I feel that the surface reflections from the side of the cabinet are contributing as well. A resonance tends to be a resonance regardless of direction. It should be there in the on and off axis responses. Surface reflections vary with direction, and when a new decay line appears that wasn't there before then it is likely to be caused by a surface reflection or edge diffraction.
Here are the 20 degree off axis measurements:
Here are the 40 degree off axis measurements:
Here are the 60 degree off axis measurements:
In conclusion, I can't see, from my measurements, anything that would lend me to believe that the EnABL'd process had any effect on the M-130/16 woofers. I also heard nothing that would make me think that it changed anything subjectively. I did see some burn in effects in the spectral decay, that while not conclusive, does indicate that the burn in process does have more of a measurable effect in the drivers output than many might have thought. This warrants further study.
I also believe that "if" the EnABL'd process were to have any effect then it would be more noted on a smaller and lighter weight full range driver only, and only if enough of more material were applied to the edges of the cone. I don't see where the pattern of the EnABL'd process would have any effect.
Your mileage may vary.
