[Xan7hos]

Been spending the better part of my work hours researching enABL process, which attempts to eliminate standing waves on both drivers AND cabinets.

Here's the article written by Bud Purvine, who's pretty big about it over at the DIY audio forum

I came across this through various discussions, particularly using it to dampen Grado drivers/cups. Though I'm not sure how one can use the enABL process to dampen the driver, the cup seems more feasible, as dampening the cups have been used since the PS-1. Another commented on a RS-1 that was enABL (both driver and cup) and remarked at a very noticeable change. While I haven't been able to contact Bud (can't get an email ...stupid DIYaudio post policies), I was wondering if anyone has any information about the enABL process as it applies to headphones?

 

[dsavitsk]

Bud is hpurvine at gmail

 

[Xan7hos]

thanks a million

 

[mattcalf]

Let us know how it goes, very interesting stuff!

 

[Xan7hos]

While people I've spoken to have said that Bud has experimented with enABL and headphones, he explains its a very daunting task, if not fatal for the headphones

Here's the response I got over at the DIY forum:

Treating headphones is a particularly daunting task.

The diaphragms are very delicate and easily disarrayed to the point of inoperable junk. Forget all Sony devices, you cannot get to the driver surface without wrecking the things. Grado HP's can be treated and according to J. Grado, who has a pair, it is more than worthwhile to do. It is, however, even more fraught with danger than others, due to the extreme thinness of the diaphragm. It took a bit to talk Grado out of applying the process by hand 10 years ago, in their plant, due to the absolute need to use Rapidiograph pens to apply the patterns. They could not convince the Japanese firm, that apparently makes everyone's diaphragms, to pre-print the plastic sheet before shaping, so the Grado project went nowhere.

Taking a set of Grado phones apart is relatively easy, but there are a lot of interference fit pieces that use a light liquid to stick them together. Once you have the driver assembly isolated it will come apart, but the coil connection wires are VERY exposed and you can easily break them. Grado will sell you another driver assembly however. I would recommend you not tackle Grado headphones first. Probably better to attempt some of the Koss Pro 4 A repop's in stead.

Just to get the hang of working with the thin diaphragms, those cheap molded sets that came with various portable CD players over the last 15 years work very well. They also sound a lot better once treated. I have also treated older, cheap, ear buds quite successfully, though you must carve off the protection plate..

If there is interest we could start yet another thread, just to cover headphones. They are very rewarding to treat and if you have the technical pens and a little 75% cut gloss coating material, it is fairly quick, once you can access the driver surface. For many units you must cut away the protective plate to do this, as they are securely glued together.

Bud

 

[smeggy]

I don;t see why this couldn't be used for newer orthodynamics as they're flat sheets between magnet arrays and pretty easy to take apart/reassemble

 

[atothex]

Whoa, I need to get my ass over to there. This is VERY interesting to me. EnABL and orthos? Yes, please!

 

[JadeEast]

I was always of the thought that the Ortho drivers had an advantage of some self dampening of internal and surface energy with the circular voice coils and driver surface being together. Not sure if they would benefit as much as a regular old dynamic driver may.

 

[Xan7hos]

For those not already checking out the DIYaudio thread, here's Bud's response in regards to applying the enABL process to cups

"Put on your imagineering hat before reading the following.

In a general sense there are two types of "cup".

For an enclosed cup, with solid walls, I would EnABL the inside surface of the outer edge of the cup, about a full pattern width below where the bezel stops when it is mounted. Treat it just as you would a cabinet EnABL in that the entire distance around the shape is the length of the pattern rings, just as the circumference of a cone is the "length" for a pattern set applied to it. I would do this before thinking about adding dampening material to the cup. If you need any it will be far less than would be the case without the EnABL pattern in place.

You should also treat both sides of the driver mounting bezel, again using the rules laid out for patterns applied to cones as a guide for size.

You could experiment with another pattern ring about 2/3 of the distance down the cup, towards the center of the cup. I am sure there are resonant nodes that need to be disrupted, but finding them may be a real chore. You can try the tap test we use on cones to find these nodes, but no guarantee of success here. Take a thin solid rod, the end of the pen nib holder for the calligraphy pens works well, and tap in a radial line from center to outer EnABL patten ring. If you can find the nodes in this fashion there will be a slight but noticeable change in "direction" of the decay from the individual tap. Right at the point where this decay changes needs to have an EnABL pattern applied. I have ho experience here, so you will have to decide for yourself. Just learning to distinguish the decay and direction of the decay is time consuming. Might be best to try to discover one on a cone first.

The other type of "cup" is that found on Grado and other open air headphones. For these you need to think of EnABL as a release agent for every edge that the sound wave detaches from, as it expands and encounters new surfaces. You can treat everyone of these and have a noticeable improvement in clarity, but some of them will be a real problem to get done. As a general rule I treat the surfaces that will be flat to my ear, just before they join to a vertical surface and just after they begin from an opening that has a vertical surface that goes toward the driver surface. This eliminates most of the need to treat those vertical surfaces, even though doing so will provide greater clarity too. Some of these surfaces are very narrow, just the edge of a tube basically, but it is important to pattern them if at all possible. If it is not possible then resign yourself to patterning the end of the tube nearest your ear, on the inside of the tube surface.

Now, before we go further I think the moderators should decide whether we need to start a new thread. Cal?

Bud"

 

[audiowize]

I have met with and spoken to Bud, and I have listened to treated drivers. While I respect Bud's transformer design capabilities and actually really really like him in a social setting (really, this guy is relaxed and chatty), the tweaky stuff he does smells more of a mirage than anything to me.

We spent some time discussing some $80 speaker add-ons that look like 3" of shoe lace with a single banana plug on the end. His assertion is that these enhance electron flow yaddah yaddah yaddah...

Anyway, electron flow is not improved by tacking something on that is out of the circuit loop. I discussed this at length with a small signals engineer (PhD in Physics) who built circuits with a noise floor of 10 electrons (so yes, this stuff does get countable) and we had a good laugh about it.

Adding mass with these dots also seems very counterproductive...