soongsc,
Look at the last post, #30 on the third page of this thread, for a patent drawing of how to treat a dome and mounting plate. Then look at the third post from bottom on page 8. Post #78, of this thread to see an almost complete treatment of the front surface of a dome and cone/dome system by ultrakaz. He also posted on another thread, on page two, about treating a pair of Fostex drivers with both Mamboni and EnABL and what his subjective responses were.
http://www.diyaudio.com/forums/showthread.php?s=&threadid=100391&perpage=10&pagenumber=2
Then go to Positive Feedback Online, here:
http://www.positive-feedback.com/Issue21/standingwaves.htm
Scroll to the bottom of the article and look at the three sets of comparisons of abstracted CSD plot time points of a cheap paper cone tweeter. The last comparison is the actual benefit of the EnABL process, though amplitude differences and frequency smoothing can also be found in most drivers. Not the purpose of the process, however.
Bud
Look at the last post, #30 on the third page of this thread, for a patent drawing of how to treat a dome and mounting plate. Then look at the third post from bottom on page 8. Post #78, of this thread to see an almost complete treatment of the front surface of a dome and cone/dome system by ultrakaz. He also posted on another thread, on page two, about treating a pair of Fostex drivers with both Mamboni and EnABL and what his subjective responses were.
http://www.diyaudio.com/forums/showthread.php?s=&threadid=100391&perpage=10&pagenumber=2
Then go to Positive Feedback Online, here:
http://www.positive-feedback.com/Issue21/standingwaves.htm
Scroll to the bottom of the article and look at the three sets of comparisons of abstracted CSD plot time points of a cheap paper cone tweeter. The last comparison is the actual benefit of the EnABL process, though amplitude differences and frequency smoothing can also be found in most drivers. Not the purpose of the process, however.
Bud
BudP said:
I was wondering whether thickness of the pattern makes significant difference. But it seems like I will have to try myself (as always). The examples are all non-metal coned drivers, so they are irrelevent to my test. I suspect the painted drivers alone improves the spectral decay and frequency response.
I might even do an FEA on a cone just to figure some things out. Man, I wish driver designers would do better work at this.
soongsc,
Sorry, forgot that detail.
On metal cones, of which I have treated probably 50 plus, including the original Ohm F's this pattern was developed on, the dried paint thickness does not exceed .003 inch and is usually less than .002 inch. The added mass is negligible. I do coat the metal drivers with the Micro Gloss product from MicroScale products. Typically just over the pattern area, thus adding about another .002 maximum to the block height.
Ultrakaz used a much thicker acrylic paint to form the blocks on the Fostex driver and since there was already a varnish applied to the paper, sealing it, the height and likely also the mass would have been greater than I normally use.
Again we are controlling the emitting surface only, even though that has a profound effect upon the performance of the driver it is only surface effect, boundary layer interaction, that the EnABL pattern id useful for.
Bud
Sorry, forgot that detail.
On metal cones, of which I have treated probably 50 plus, including the original Ohm F's this pattern was developed on, the dried paint thickness does not exceed .003 inch and is usually less than .002 inch. The added mass is negligible. I do coat the metal drivers with the Micro Gloss product from MicroScale products. Typically just over the pattern area, thus adding about another .002 maximum to the block height.
Ultrakaz used a much thicker acrylic paint to form the blocks on the Fostex driver and since there was already a varnish applied to the paper, sealing it, the height and likely also the mass would have been greater than I normally use.
Again we are controlling the emitting surface only, even though that has a profound effect upon the performance of the driver it is only surface effect, boundary layer interaction, that the EnABL pattern id useful for.
Bud
Bud,
What I'm trying to figure out overall effect. For example, reynolds number will be part of the factor determining the boundary layer thickness and whether we have a turbulent or laminar boundary layer depending on surface roughness. With the type of paint that I had used in the past, 0.5cc would amount to around 0.25g of dry paint which also effects a small metal cone driver. So these are some of the things I try to figure out. I also try to be prepared to restore original driver characteristics if the results are not what I expect.
In this case, I will be using alcohol removeable paint. I have used toothpaste for some tests as well.
What I'm trying to figure out overall effect. For example, reynolds number will be part of the factor determining the boundary layer thickness and whether we have a turbulent or laminar boundary layer depending on surface roughness. With the type of paint that I had used in the past, 0.5cc would amount to around 0.25g of dry paint which also effects a small metal cone driver. So these are some of the things I try to figure out. I also try to be prepared to restore original driver characteristics if the results are not what I expect.
In this case, I will be using alcohol removeable paint. I have used toothpaste for some tests as well.
Because some squares aren't as shiny/pronounced as the others. Like they've been soaked up a little.
I did these without templates..(as you can see)..just outer pair start with overlap....inside pair of squares start parallel with last outside pair...repeat.
An externally hosted image should be here but it was not working when we last tested it.
I did these without templates..(as you can see)..just outer pair start with overlap....inside pair of squares start parallel with last outside pair...repeat.
I asked this before and got no repsponse. Why not use adhesive back felt for the Mamboni process? It is available at many hardware stores and also at McMaster-Carr online. You would probably be able to remove it, if it was not to your liking and not ruin a cone.
Bud, on the EnAble I have the same questions. Why not cut out small rectangles from adhesive tape, scotch tape, packaging tape, adhesive back mylar, etc. It would then be removable. You could lay out a long peice of 2" wide tape on a clean hard surface and cut a line of grids throug the tape with a sharp exacto blade and then peal each one up and place with some tweezers or something similar. Maybe the rectangles are too small for the inner side of the cone, but it seems like it could work for the outer edge. I'm thinking mostly of using this kind of application on a smooth, metal cone drivers. Any thoughts?
Bud, on the EnAble I have the same questions. Why not cut out small rectangles from adhesive tape, scotch tape, packaging tape, adhesive back mylar, etc. It would then be removable. You could lay out a long peice of 2" wide tape on a clean hard surface and cut a line of grids throug the tape with a sharp exacto blade and then peal each one up and place with some tweezers or something similar. Maybe the rectangles are too small for the inner side of the cone, but it seems like it could work for the outer edge. I'm thinking mostly of using this kind of application on a smooth, metal cone drivers. Any thoughts?
Hi Gang,
Polly S is available from the Testor web site: http://www.testors.com/catalog_brand.asp?brandNbr=2&ictNbr=57
Microscale is available at http://www.microscale.com/Merchant2/merchant.mvc?Screen=CTGY&Category_Code=FINPROD
Hope this helps.
Polly S is available from the Testor web site: http://www.testors.com/catalog_brand.asp?brandNbr=2&ictNbr=57
Microscale is available at http://www.microscale.com/Merchant2/merchant.mvc?Screen=CTGY&Category_Code=FINPROD
Hope this helps.
I used this...I suppose ANY acrylic paint will work...and ANY modelstore should have acrylic paint.
Cost me all of € 1.75
An externally hosted image should be here but it was not working when we last tested it.
Cost me all of € 1.75
Wow, leave you guys alone for a day and look what happens....
soongsc,
Yes, by all means use an acrylic paint so that you can experiment. For small diameter metal domes I use technical drawing pens with a 50% water cut acrylic paint so that the material will flow properly. The blocks will only be as thick, in width of strip, as the pen point. As you get below 20 mm of block ring diameter, the blocks change to dots, work just as well and do not block the entire space alloted to them. Working with Titanium, the blocks retain this character, that of being smaller than their alloted space, right out to many 100's of mm of block ring diameter. So the Reynolds numbers do control how much area is swept by a block. Thickness seems less important than interruption and pattern, regardless of surface and material.
Bud
Dan,
I apologize. I remember your question and I did think on it for a while and those thoughts did actually cause me to choose a particular path on the upcoming Lowther treatment. The Mamboni triangles are currently being put on with a PVA glue. This material, for what ever reasons, does not act as a damping agent. Instead it acts as an enhancement to boundary layer activities, on soft surface paper. It is pervasive by the way, if you put it over an EnABL pattern it swamps the patterns effectiveness, but, putting the EnABL pattern over PVA works quite well. It does requires a full, single , cost of Micro Gloss.
If the glue on the felt is a relatively stiff material I suspect it would work fine, but, I have no experience with any of the Mamboni processes yet. As for the tape process I see no reason why it would not work, at least initially. You would need to have a flattened conic section with pattern printed on it to get curved blocks from. Straight line blocks will probably work, but, again I have no experience here. From other tape fiasco's I will warn you to seal the edges with the Micro Gloss to keep the adhesive from oxidizing and allowing the tape to peel. Most tapes are about .003 thick so that may or may not be a problem and the Micro Gloss will help with the edge transition. I think you should try it and report back. I will make a conic section for you, to your measurements. These do not ever fit on first pass so you will need some soft ware to manipulate the images with and if you have Corel Draw that will be perfect.
Bud
Bas,
Welcome and nice workmanship. What did you use as an applicator? Were you able to get 36 sets of blocks? Should you wish to experiment, using drastically fewer blocks will shelve high frequencies, beyond the pattern, pretty severely. I use a six block pattern, around a central dot, on domes, to kill the typical beaming from the tip of the dome. I then place a drop of PVA right in the center, using the barrel of a round toothpick, that is cut in half, for an applicator. Then one coat of Micro Gloss over than whole pattern. The PVA controls the rest of the domes emitted wave front shape, much as a phase plug will, only better and without any side effects.
I do occasionally re coat a block that seems to sink more than the rest. Often it is best to wait till all have dried to a tacky surface, before doing this. Be careful in your choice of coatings to go over the blocks, If it is not as hard or harder than the Micro Gloss you can end up with a cone slow enough to actually alter the pitch of the sound. I discovered this on a guitar speaker I treated, with a regular spar varnish overcoat. Also, flat paints seem to work best due to the amount of material suspended in the paint, as Moray James has suggested.
Thanks C2C, as usual, the right stuff, just in time.
Bud
soongsc,
Yes, by all means use an acrylic paint so that you can experiment. For small diameter metal domes I use technical drawing pens with a 50% water cut acrylic paint so that the material will flow properly. The blocks will only be as thick, in width of strip, as the pen point. As you get below 20 mm of block ring diameter, the blocks change to dots, work just as well and do not block the entire space alloted to them. Working with Titanium, the blocks retain this character, that of being smaller than their alloted space, right out to many 100's of mm of block ring diameter. So the Reynolds numbers do control how much area is swept by a block. Thickness seems less important than interruption and pattern, regardless of surface and material.
Bud
Dan,
I apologize. I remember your question and I did think on it for a while and those thoughts did actually cause me to choose a particular path on the upcoming Lowther treatment. The Mamboni triangles are currently being put on with a PVA glue. This material, for what ever reasons, does not act as a damping agent. Instead it acts as an enhancement to boundary layer activities, on soft surface paper. It is pervasive by the way, if you put it over an EnABL pattern it swamps the patterns effectiveness, but, putting the EnABL pattern over PVA works quite well. It does requires a full, single , cost of Micro Gloss.
If the glue on the felt is a relatively stiff material I suspect it would work fine, but, I have no experience with any of the Mamboni processes yet. As for the tape process I see no reason why it would not work, at least initially. You would need to have a flattened conic section with pattern printed on it to get curved blocks from. Straight line blocks will probably work, but, again I have no experience here. From other tape fiasco's I will warn you to seal the edges with the Micro Gloss to keep the adhesive from oxidizing and allowing the tape to peel. Most tapes are about .003 thick so that may or may not be a problem and the Micro Gloss will help with the edge transition. I think you should try it and report back. I will make a conic section for you, to your measurements. These do not ever fit on first pass so you will need some soft ware to manipulate the images with and if you have Corel Draw that will be perfect.
Bud
Bas,
Welcome and nice workmanship. What did you use as an applicator? Were you able to get 36 sets of blocks? Should you wish to experiment, using drastically fewer blocks will shelve high frequencies, beyond the pattern, pretty severely. I use a six block pattern, around a central dot, on domes, to kill the typical beaming from the tip of the dome. I then place a drop of PVA right in the center, using the barrel of a round toothpick, that is cut in half, for an applicator. Then one coat of Micro Gloss over than whole pattern. The PVA controls the rest of the domes emitted wave front shape, much as a phase plug will, only better and without any side effects.
I do occasionally re coat a block that seems to sink more than the rest. Often it is best to wait till all have dried to a tacky surface, before doing this. Be careful in your choice of coatings to go over the blocks, If it is not as hard or harder than the Micro Gloss you can end up with a cone slow enough to actually alter the pitch of the sound. I discovered this on a guitar speaker I treated, with a regular spar varnish overcoat. Also, flat paints seem to work best due to the amount of material suspended in the paint, as Moray James has suggested.
Thanks C2C, as usual, the right stuff, just in time.
Bud
BudP said:
I think the concept is beginning to make sense. Since the wave travelling across the cone is at sound speed, small disruption should cause separation. But it also seems sticking clean edged cutouts should be more effective than paint. Also we would probably need more separation for a convexed surround than a concaved surround.
BudP said:
Bud,
I downloaded your pattern file you originally posted and simply messed with the printing percentage until I got a conic size that matched the dia of my woofers, right at the inside edge of the surround. The pattern was, of course, sized right along with it. Is this an appropriate method? If so, I can print the pattern on adhesive back mylar and simply cut the 36 pairs out from that. Does that make sense?
I will have to read back to see what the process is and when to apply the Micro Gloss. The driver is an aluminum cone, very thin and does have a satiny black, smooth, non-sticky coating, though I have no idea what it is. Would the pattern alone possibly suffice or is the Micro gloss layer an absolute?
I have a pair of 15" JBL woofers on which the Manboni/enABL treatment could be beneficial. Here are the response curves: http://audioheritage.org/vbulletin/showthread.php?t=10655
There is a huge peak at around 1.7Khz and I wonder how the treatments discussed work there. I am inclined to begin with the Mamboni treatment on the back.
I have a tube of JBL "Moyen RS-3087 Cement" glue (which is the one used by jbl to construct the drivers). Would it work well with the mamboni treatment or what sort of PVA glue should I get. I see the glue is applied in such a way that it extends toward the center of the cones beyond the felt triangles: is this done on purpose?
(Sorry if this have been covered before, I have read a lot of the two or three treads where these things has been considered, but found few comments about the particular glues (other than the one from Partsexpress) and felts being used or that are appropriate. As I am in Germany I would like to source everything locally (many Train-model fans here, so I guess sourcing the materials for the enABL should not be that difficult.)
There is a huge peak at around 1.7Khz and I wonder how the treatments discussed work there. I am inclined to begin with the Mamboni treatment on the back.
I have a tube of JBL "Moyen RS-3087 Cement" glue (which is the one used by jbl to construct the drivers). Would it work well with the mamboni treatment or what sort of PVA glue should I get. I see the glue is applied in such a way that it extends toward the center of the cones beyond the felt triangles: is this done on purpose?
(Sorry if this have been covered before, I have read a lot of the two or three treads where these things has been considered, but found few comments about the particular glues (other than the one from Partsexpress) and felts being used or that are appropriate. As I am in Germany I would like to source everything locally (many Train-model fans here, so I guess sourcing the materials for the enABL should not be that difficult.)
Dan,
That is the correct approach. You do want a about a block width of space between the lower edge of the surround and the top edge of the top row of blocks.
I would listen to the cone, if possible, before applying the Micro Gloss. The decision point here, for me, is what amount of "constraint" or "repression" does the sound now have. If it sounds as if the energy is just not getting off of the cone then coat the area of pattern blocks on both the cone and blocks. I am fairly sure this will be needed, but if I were doing the work, I would proceed in this fashion.
Sorry to use such spongy terms but audio sound is not like snow sound and the Aleut people, where every format of snow is carefully described and everyone has the same information for qualitative differences. After just a short exposure to this treatment process you will know exactly what I mean with these words.
Also, you might try hooking the driver up and playing some soft music through it, to gain some experience with what changes occur as you near completion of the pattern rows.
Don't ignore the inner row and dome. Go back to page 8 of this thread and look for post #78 where I posted treatment done by ultrakaz on a Yamaha speaker.
Bud
That is the correct approach. You do want a about a block width of space between the lower edge of the surround and the top edge of the top row of blocks.
I would listen to the cone, if possible, before applying the Micro Gloss. The decision point here, for me, is what amount of "constraint" or "repression" does the sound now have. If it sounds as if the energy is just not getting off of the cone then coat the area of pattern blocks on both the cone and blocks. I am fairly sure this will be needed, but if I were doing the work, I would proceed in this fashion.
Sorry to use such spongy terms but audio sound is not like snow sound and the Aleut people, where every format of snow is carefully described and everyone has the same information for qualitative differences. After just a short exposure to this treatment process you will know exactly what I mean with these words.
Also, you might try hooking the driver up and playing some soft music through it, to gain some experience with what changes occur as you near completion of the pattern rows.
Don't ignore the inner row and dome. Go back to page 8 of this thread and look for post #78 where I posted treatment done by ultrakaz on a Yamaha speaker.
Bud
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