EnABL

[chris661]

So you're inducing cone ringing, figuring out which direction the resonance propagates, and then drawing patterns to...?

Do you want to stop the resonance propagating, or damp the resonance out altogether?
What if the resonance doesn't propagate radially, instead following a more complex pattern?

I'll admit that I'm skeptical of enabl, but willing to listen to explanations. The physicist in me is curious.

I'm trying to figure out a way of seeing the way a cone bends, too. High-speed cameras would need reference points, but using laser interferometry and mapping the cone pixel by pixel could produce useful results, especially if it can be mechanised.

Chris

PS - its important to note that a seperate set of reflections appear from the cabinet, on a milli-second timescale. These must be eradicated too.

[IslandPink]

It's definitely the sort of information I needed, Bud. At the moment I can't say for sure I'm hearing it the way you are, enough to fix on a particular radius . So far I've been using an empty plastic pen, or a 3mm twist-drill ( blunt end ) to do the tapping. I should try & find or whittle a piece of wood I suppose.
What I'm hearing so far is a sort of a deeper tone with more of a note , when I'm tapping in the interior of the cone ; this then transitions to more of a neutral or brighter tone as I go outwards. Trouble is, the transition is just gradual from centre to edge.
I will do some more later & see if I can get my ear to be more educated .

Chris, I think the resonance does propagate radially and around the cone - it's just that there may be a bias inwards or outwards depending on how far you go out . If the cone is symmetric , there shouldn't be much of a difference in its behaviour as you go round the cone ; except that I can definitely hear differences to the decay in the area where the little briaded wires connect to the cone .....

[BudP]

Mark, I do think your current taping devices may be a bit too massive. Go and find a fine line artists paint brush and use that wand end for your exciter. Best to not tap near the wires glued into the cone. As for what you are hearing, it is likely you are using more force than is needed, you really do want a very light stroke, just enough to excite the local area and you want a wand with mass suited to bouncing off the cone from a single stroke.

So you're inducing cone ringing, figuring out which direction the resonance propagates, and then drawing patterns to...?

Drawing patterns to disperse that null zone. Once the pattern has been applied the null zone disappears and all resonance decay moves in an outward, towards the surround, direction. The patterns, once set, do provide a local area discontinuity and applied circumferentialy are enough to eliminate the problem. What you hear, with intelligible signal, is a lack of lobbing to discreet frequency bandwidths. Dispersion becomes gradual in it's frequency component change, if you move your listening point back and forth across the driver. Intelligible signals include pink, white and musical noise.

Do you want to stop the resonance propagating, or damp the resonance out altogether?

I want to control how the resonance propagates. Rather than a number of torus shaped emission rings, with recirculating information structure, I want one large torus shaped emission out into the room. Do look at the youtube video to actually see the circulation of driven particles above a resonance torus

What if the resonance doesn't propagate radially, instead following a more complex pattern?

I think the patterns are eliminating the basic structure that allows more complex patterns to form. I also think the basic structure we are after is created by emission of transverse waves, from their containment within the cone. I think these emissions cause all of the effect that we call "break up" because that also audibly disappears. And, all of this change in activity does cause measurable, though subtle, changes in typical test portrayal.

[IslandPink]

Mark, I do think your current taping devices may be a bit too massive. Go and find a fine line artists paint brush and use that wand end for your exciter.

Good tip . I found a paintbrush upstairs, that I use for retouching photos.
With this I reckon I can hear what you're describing . There is a more localised change of the character of the sound . It seems to be around 60% of the way out from the dome 'joint' to the cone edge , on the FE103E . I'll do more tapping tomorrow .

So, I guess the next question ( no doubt covered in the many threads ) is what's the material for the EnABL patterns ? ( also there's these special roller pens that are required ..will read up on this ) .

[BudP]

For the least obvious pattern we use a clear, flat, acrylic model train/car paint. This material will provide a small lump when dry, about 0.002" high, which is just enough. The pens have no rollers or other expensive apparatus, just an A series calligraphy pen.

You can purchase a set of pens and some of the acrylic paint from Ed LaFontaine here. http://www.diyaudio.com/forums/showthre ... genumber=1

A series of pictures that show how to use the pens here. https://plus.google.com/photos/11328970 ... -N6Dz-O8Vg

General tutorial is here. http://www.diyaudio.com/forums/multi-wa ... ost1460272

[chris661]

I think the patterns are eliminating the basic structure that allows more complex patterns to form. I also think the basic structure we are after is created by emission of transverse waves, from their containment within the cone. I think these emissions cause all of the effect that we call "break up" because that also audibly disappears. And, all of this change in activity does cause measurable, though subtle, changes in typical test portrayal.

I can see what you're getting at, though your use of the term "null zone" confuses me a little - there's a couple of physics research papers that mention the term, but not much else.
From the context, though, I'd guess you mean a bit of the cone that is not vibrating.
Then the wave continues in a radial direction, to be dissipated by the surround. So you're getting the surround to dissipate a little more energy.

I wonder if it'd be possible for a wavefront to propagate ~circularly. That could end up being your longest decay mode once the radial ones are taken care of.


I need to break out my FE126E drivers treated by Dave. I think my biggest gripe with them is increasing harmonic distortion as you get above girl & guitar listening levels, though I suspect the ridiculously tiny motor is at least partly to blame for that.

Chris

[IslandPink]

Chris, those drivers had about the best female vocal quality I've ever heard - and from CD source !

Bud, just bought a pen on EBay.
http://www.ebay.co.uk/itm/351398901182
Not easy to find all the nib options on Speedball pens from the UK, but this kit has some A and B nibs - hopefully enough for my purposes. I'll look out for some acrylic paint at the weekend while shopping in Warrington.

[chris661]

I had them for a while crossed over around 500Hz to some mini-subs.
Problem was that, as you turn the volume up, the Fostex starts sounding louder than the other drivers - it was adding its own harmonic distortion, clearly audible if you just play a single tone.
Then you've got to mess with the relative levels to get it sounding balanced again.

If you run the Fostex driver on its own, its pretty damn good. You can't get much bass out of them, though. They're like flea-watt SETs - not the last word in oomph, but fit certain things really really well.

Chris

[BudP]

The pen tips are a start. You will end up needing a #2 and less often a #4. The paint needs to be a flat rather than a gloss. The material used to cut surface reflection sets up thicker than a gloss paint. You will get the best results from going to a brick and mortar plastic model or model train retailer. Ask for a clear flat paint with an acrylic base. Not to be confused with acrylic artist paints.

I wonder if it'd be possible for a wavefront to propagate ~circularly. That could end up being your longest decay mode once the radial ones are taken care of.

Every cone driver I have treated in the last 5 years, that was larger than a 6 inch nominal marketing diameter, had this rotating resonance out at the final 1/4 to 3/8 inch of the diaphragm. There is a subduction of the tap test resonance there, especially leading edge strike tone. The youtube video series shows them clearly. Called Raleigh waves I believe. They require a pattern at the lower edge of the subduction condition and a damping material on the back side directly under neath the width of subduction. An ever sticky damping material is most suitable.

I have attached a laundry list of various links for EnABL.

[Scottmoose]

A minor point, but in re the FE126E it actually has a outsized motor, not a 'ridiculously small' one, as amply revealed by its over-damped Qt. From a technical perspective their characteristics with excess electrical damping, short VC and gap make them horn drivers in the traditional sense (i.e. reactance-annulled front loaded types). Available BW for horn loading stretches from 9.5Hz - 518.5Hz assuming no other changes to system Q. Fostex were of course targeting the requirements of their primary Japanese market in its balance of properties, which made them intended for use on the end of high output impedance amplification, with reasonably efficient back loads in small rooms at modest average SPLs. The current En series unit seems to have eased back on these slightly; mechanical damping has dropped & total Q risen a little, likely reflecting the new design team's priorities & the increased popularity of solid state in addition to valves amongst Japanese wideband enthusiasts. It is what it is: a horn driver, that has been adapted for use in a related but different approach. You can get bass out of it run sans support if you're
a/ Prepared to accept a large horn. As in 'large'
b/ Prepared to partner it with suitable amplification to raise effective system Q & lower Fh < 300Hz (or employ digital delay) and
c/ Do not require high SPLs, since there's a limit to how much you can raise system efficiency & keep HD within manageable levels, which is a matter that varies with individuals, programme material & also cultures.

[IslandPink]

Well said Scott. These drivers can be very good used within their limitations. Hopefully I'll get to hear one of the new En drivers soon. There's an upgrade for the 103E when I need it !

Bud : Failed to get the paint this weekend as the two potential shops in Warrington have closed down. Will get some more locally on Friday, I reckon.
In the meantime, I just want to clarify how the 'mask' is used. I can scale the pdf file as appropriate once I've decided on the radius . What happens next ? - Do I put the mask in place on the cone and pencil-on the small rectangles onto the cone then remove it & paint ? ; or do I go straight in with the calligraphy pen and put the paint onto the cone ?
How do you keep the paper mask in place in close contact with the cone ?

[BudP]

I just want to clarify how the 'mask' is used. I can scale the pdf file as appropriate once I've decided on the radius . What happens next ? - Do I put the mask in place on the cone and pencil-on the small rectangles onto the cone then remove it & paint ? ; or do I go straight in with the calligraphy pen and put the paint onto the cone ?

Different mind set. The patterns are mere guides, nothing so important as masks or masques. Their use is as a guide, sitting just below or above, the location for the pattern. Please look at this particular set of photos to get a portrayal.

https://plus.google.com/photos/11328970 ... banner=pwa

How do you keep the paper mask in place in close contact with the cone ?

We can still use gravity and proper orientation here in the backwards, once colonies.

[IslandPink]

Ah, now I understand .
I have some small pots of the right type of paint now, and the pens.

[BudP]

Please practice using the pen held upside down when applying the marks. See here for hints.

https://plus.google.com/photos/11328970 ... -N6Dz-O8Vg

[IslandPink]

Well, I had a go at this eventually. I couldn't hear the specific transition Bud was describing, so I just took the picture of the FE126e from Bud's picture vault and scaled the percentage radii of the outer blocks in relation to the full cone diameter, and applied these numbers ( = 64 and 61mm ) to the FE103e .
I used a template , scaled , from Dave Dlugos to get the output markings in the right place combined (first) with pencil circles at the right radii done with a compass , with the point resting on a couple of layers of masking tape placed over the dome of the centre-cap . This worked well .
I found the Speedball pens pretty difficult to use . The No.3 square-tip one wasn't bad, but the No.5 one refused to dispense any paint most of the time or threatened to deposit a massive blob of paint, but nothing in between . I used the No.3 for the outside rings and the No.5 for the inner ring. I didn't spend any time agonising over where to put the little blobs on the inside ring - just went round free-hand keeping the first set pretty close to the inside near the glue.
Paint was Humbrol matt acrylic paint in a dark blue colour which looks completely black when applied to the cone

Anyway it's done on one driver ( pic below ) . Not bad if you don't look to closely. Hopefully it will be good enough functionally to do the Enabl 'thing' .

I will report back later this evening on the sound, once the paint has properly dried .