EnABL'd woofers tested

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Danny Richie

EnABL'd woofers tested
« on: 17 Sep 2008, 08:31 pm »
I did a fairly thorough set of testing and listening test to a couple of my woofers that had this EnABL'd process done to them. It will take a while to post all the measured data, explanations, and listening comparisons, but if there is enough interest I will do so.
« Last Edit: 22 Sep 2008, 04:45 pm by Danny »


Re: EnABL'd woofers testing
« Reply #1 on: 17 Sep 2008, 08:36 pm »
What is your subjective opinion Danny?  Also, which drivers were enabled?



Re: EnABL'd woofers testing
« Reply #2 on: 17 Sep 2008, 08:50 pm »
I'm very interested as I was considering doing this to the midrange drivers in my HT8's.


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Re: EnABL'd woofers testing
« Reply #3 on: 17 Sep 2008, 08:57 pm »
By the way he said that, I am betting its not conclusive, nor universal...


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Are: Enabled woofers testing
« Reply #4 on: 17 Sep 2008, 10:08 pm »
I'm interested. It seems that the majority of people who have tried it have reported favorable impressions. The sceptics, those who havn't tried it, are good at shouting down the devotees because the scientific evidence has been thin to nonexistent. Its curious that such an innocuous technique has generated such ardent stances on both sides of the fence. WTF is going on here Danny?


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Re: EnABL'd woofers testing
« Reply #5 on: 17 Sep 2008, 11:06 pm »
I'm interested.


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Re: EnABL'd woofers testing
« Reply #6 on: 18 Sep 2008, 09:16 am »
very interested


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Re: EnABL'd woofers testing
« Reply #7 on: 18 Sep 2008, 01:09 pm »
I'm very interested too.  This process was on my radar scene late last year but seemed to fad from the forums.  I speculated it was because the process was non reversable and not enough hard data to support the time and effort to perform.   Thanks for doing the grunt work for us...again.   :icon_lol:

So, this is what has been keeping you so busy and not working on my servo request.  :duh:


Danny Richie

Re: EnABL'd woofers testing
« Reply #8 on: 18 Sep 2008, 02:11 pm »
So, this is what has been keeping you so busy and not working on my servo request. 

We decided to honor your request.

Danny Richie

Re: EnABL'd woofers testing
« Reply #9 on: 18 Sep 2008, 04:07 pm »
Okay be ready for some reading:

One of my customers had a couple of M-130/16 woofers treated with this process and sent to me.

I also contacted Bud and asked him about the process and his subjective evaluations.

Bud really liked the M-130 woofer, by the way. It will really only play out to about 10kHz but he really liked it as a full range driver. Unlike a lot of other drivers it really doesn't have much in the way of stored energy or upper end break up. So I kind of wondered if it was really a poor candidate for a treatment designed to minimize stored energy or break up issues. Bud did say though that the process appeared to improve the sound of the driver to him.

I then asked Bud about how he went about listening and comparing the sound of the driver before and after treatment. I really figured he'd leave one driver untreated as a control and then treat the other one to compare, but he said he treats them both together being careful to do the same thing to each driver. I must admit that it is pretty artistic in the way it is applied. However treating both woofers doesn't allow for a control (one treated and one not treated).

Bud said he would listen to the woofer, then apply some treatment. He would then listen again, and apply more treatment and repeat the process until it sounded right. He also noted that there would be about 30 minutes of time passing from the time he listened, till the time he treated it, and listened again. Another thing to note was he listened to it in free air with no enclosure.

I kind of suspected that what he could be hearing that was different (if he indeed was hearing something different) was due to the amount of play time it got between each treatment. In other words the driver was burning in more and more the more he played it and he was noticing the smoothing out and relaxing of the sound due to that effect.

So I started out measuring each woofer in an A/V-1 box (small ported enclosure) playing full range and took the measurement with 1 watt and at 1 meter.

I also measured a fresh out of the box pair. So I had a pair of each.

The frequency response was a little off (not in a bad way) on one of the EnABL'd woofers from the other three (off a little but within a normal tolerance range). The other EnABL'd driver had nearly an identical response curve to one of the stock woofers. So there was nothing out of the ordinary with the response curves. All were within a normal range, but you can't see stored energy in a response curve.

I then looked at the spectral decays of each of the four woofers. Differences were pretty minor and well within normal tolerances for these drivers. None of them stood out as being different.

It was really hard to see much in the way of anything adverse because there just wasn't anything bad going on with these drivers. So when viewing the spectral decays I bumped the level up above reference by blowing the top line off the scale so as to reveal more further down in range. In other words, 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. Now I was seeing 30db down ranges in the graph. Even still, the output was pretty much gone before anything reached much more than a 2.5 ms time frame.

I still suspected the sonic differences might be due to break in. I couldn't measure the EnABL'd drivers prior to the treatment so decided to measure the other two control woofers again and run spectral decays again after 48 hours of fairly hard play time. So those two woofers got a 50Hz sine wave for two days.

I then ran spectral decays again under the same conditions and set up. The spectral decay was a little bit cleaner on both woofers as some of the small traces moved around a little. What was really interesting is that both woofers had a little cleaner decay below 1kHz. This is very telling of what is often observed from burn in effects, and warrants further testing to see how much cleaner the spectral decay gets after burn in.

See two stock woofers after burn in:

BTW, I posted some new burn in data here that address some of the Internet based burn in myths: http://www.gr-research.com/myths.htm

It only makes sense that the woofer will have less stored energy after burn in as the compliance softens up. It is kind of like putting more or less air in the air shocks on a car. More pressure and a stiffer ride means that it bounces up and down a little longer before returning to rest. Less air pressure (a softer suspension) and it settles to rest quicker.

Interesting though the upper ranges remain relatively unchanged after burn in. Where the wavelengths get shorter the stored energy tends to be more in the cone itself rather than the suspension. The suspension becomes more in play as wavelengths increase and exertions get longer.

(This post exceeded 10,000 characters so I am having to break it up)

Danny Richie

Re: EnABL'd woofers testing
« Reply #10 on: 18 Sep 2008, 04:07 pm »
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.

Danny Richie

Re: EnABL'd woofers testing
« Reply #11 on: 18 Sep 2008, 04:11 pm »
One last pic:

There was also a shinny clear coat that was sprayed over the entire woofer.


Re: EnABL'd woofers testing
« Reply #12 on: 18 Sep 2008, 05:40 pm »
Was this the RA8 customer?

Personally I agree with you .We dropped the Enabl several months ago,but do my own treatments not Enabl.

Not surprizing results as others have noted the similar results with measurments.But well done Danny :thumb: :thumb:

Smaller drivers may have a advantage in the fullrange area.

OK Danny get the boys together and do a blind curtain listening test.

See if Art and others agree.People who do the treatments or have it done swear up and down there is a difference.

Again work you just needed to spend a few days doing and documenting :duh:


Re: EnABL'd woofers testing
« Reply #13 on: 18 Sep 2008, 05:52 pm »
WOW, killer w/u!   :thumb:


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Re: EnABL'd woofers testing
« Reply #14 on: 18 Sep 2008, 06:11 pm »
Good analysis Danny - thanks for taking the time to do it and write it up.  A couple of years ago, I was corresponding with Al re my idea to apply something to the cones of TB full-rangers.  Someone in Europe was using a very expensive compound (over $100 /ounce as I recall), and I had an idea to use something from the woodworking industry.  Al said I was sneaking up on the EU stuff.  I never did any testing, but used it on the few BozeBuster drivers I built.  It seemed to "sound" better, but that was completely subjective with no DB testing.


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Re: EnABL'd woofers testing
« Reply #15 on: 18 Sep 2008, 09:29 pm »

Great write up and thank you for testing this out for folks to review.  Danny, does it look like Bud coated the rear of the cone too?  IIRC, there were those who were experimenting with clear coating the rear also.

The design on the cone and dust cover sure looks purdie, but also looks like a bull's eye for children to zero in on if one were to go grill-less.  I have a nephew who would have shot his nurf gun at it within 18 seconds of being in my house.   :nono: :x

Danny maybe your next experiment could be to look at the Dr. Mamboni experiment?  Anyone out there do one of Danny's mid/woofers with the Dr. Mamboni treatment?  Just in case this is new to anyone here are some pictures -

Al, what treatment are you doing to your drivers?


Danny Richie

Re: EnABL'd woofers testing
« Reply #16 on: 18 Sep 2008, 09:40 pm »
Companies have been doing this stuff for years. Does this speaker look familiar?


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Re: EnABL'd woofers testing
« Reply #17 on: 18 Sep 2008, 09:57 pm »

Yes, Dunlavy made some amazing speakers...large and small sweet spot.

Here is another one done in red