FOSTEX 127 E
Here is a surprise for all of you. You can now tease Planet 10 for his courage in supplying the victims.
This is a curvilinear cone, rather than a straight conic section as is true of Lowthers. Because of this I have only provided treatment rings and photos.
The tool set has an additional requirement, over that found with the Lowthers. You must now purchase, or unearth, a Rapidiograph or Mars technical drawing pen. The Fostex needs the number 2, Red, 0.65 pen tip from Rapidiograph. I do not know the equivalent size number from Mars. The flat Poly S Acrylic paint must be cut by 50% with pure water. You need to be ready to treat all of the drivers on the inner block rings at one sitting just to keep from having to clean and refill. In addition you need to move fairly quickly through the treatment, to keep the tiny passages from setting up and clogging. The reload shake, that is needed with heavy India ink in these things, is even more important with the paint. Plus you will need to use a finger nail to clear dried paint from the tip, step cut and barrel end, as you go along.
Use the two block sets in the upper cone ring to aim the lower block ring that sits between and below them. After the ring on the cone and the ring on the epoxy joint have been applied apply the center dome lower ring, aligning it with the ring on the cone, across from it. Your eyes must be clear for this and it is better not to drink coffee until after you are done.
You will see in the pictures that there is a set of rings, reduced to three block sets per ring, around a spot placed more or less on the top center of the dome. Absolute centering is hard to do and does not seem to be needed, but, close to center is good.
The cone outer ring is straight forward and you can align it with the inner ring if you wish to. Misalignment will be meaningless here. The pen used on this outer ring set is an A 4 tip.
I will be coating these with Micro Gloss tomorrow, along with applying a PVA droplet on top of the center spot on the dome. I will report back on the number of coats of Micro Scale Gloss coat needed, but I expect it to be a nominal three to one coating ratio, for cone to dome. However, I am planning on using a 50 % cut with water to Gloss coat material for the center dome. This will allow me to approach the proper ratio in two steps, just to keep the high frequencies from becoming predominant.
Here is the link to the photos for the cone and dome patterns and I have attached a PDF of the treatment rings. This PDF has a ring for the backside of the cone that I am not planning to use here as the cone material is almost as thin as that of the Lowthers and I do not think a backside pattern will be needed.
http://picasaweb.google.com/hpurvine/Fostex127ETreatment
Bud
Here is a surprise for all of you. You can now tease Planet 10 for his courage in supplying the victims.
This is a curvilinear cone, rather than a straight conic section as is true of Lowthers. Because of this I have only provided treatment rings and photos.
The tool set has an additional requirement, over that found with the Lowthers. You must now purchase, or unearth, a Rapidiograph or Mars technical drawing pen. The Fostex needs the number 2, Red, 0.65 pen tip from Rapidiograph. I do not know the equivalent size number from Mars. The flat Poly S Acrylic paint must be cut by 50% with pure water. You need to be ready to treat all of the drivers on the inner block rings at one sitting just to keep from having to clean and refill. In addition you need to move fairly quickly through the treatment, to keep the tiny passages from setting up and clogging. The reload shake, that is needed with heavy India ink in these things, is even more important with the paint. Plus you will need to use a finger nail to clear dried paint from the tip, step cut and barrel end, as you go along.
Use the two block sets in the upper cone ring to aim the lower block ring that sits between and below them. After the ring on the cone and the ring on the epoxy joint have been applied apply the center dome lower ring, aligning it with the ring on the cone, across from it. Your eyes must be clear for this and it is better not to drink coffee until after you are done.
You will see in the pictures that there is a set of rings, reduced to three block sets per ring, around a spot placed more or less on the top center of the dome. Absolute centering is hard to do and does not seem to be needed, but, close to center is good.
The cone outer ring is straight forward and you can align it with the inner ring if you wish to. Misalignment will be meaningless here. The pen used on this outer ring set is an A 4 tip.
I will be coating these with Micro Gloss tomorrow, along with applying a PVA droplet on top of the center spot on the dome. I will report back on the number of coats of Micro Scale Gloss coat needed, but I expect it to be a nominal three to one coating ratio, for cone to dome. However, I am planning on using a 50 % cut with water to Gloss coat material for the center dome. This will allow me to approach the proper ratio in two steps, just to keep the high frequencies from becoming predominant.
Here is the link to the photos for the cone and dome patterns and I have attached a PDF of the treatment rings. This PDF has a ring for the backside of the cone that I am not planning to use here as the cone material is almost as thin as that of the Lowthers and I do not think a backside pattern will be needed.
http://picasaweb.google.com/hpurvine/Fostex127ETreatment
Bud
I've bought a couple cheap fullrange speaker (around 3.5 USD each) with surprisingly good sound and quality !!!, I'll try Enabl pattern after I got some things sorted out here.
current problem : I don't know where to buy acrylic paint and the conformal coating(floor wax) in China
so this might take a while. and buying 1 large can of floor wax is a bit wasteful.
Hartono
current problem : I don't know where to buy acrylic paint and the conformal coating(floor wax) in China
so this might take a while. and buying 1 large can of floor wax is a bit wasteful.Hartono
Hello Hartono,
I'm up a bit earlier than BudP because I'm in a different time zone and thus able to provide you with an answer a bit earlier due to the time difference.
The acrylic paint that BudP uses is made by a division Testors and is called Floquil - http://www.testors.com - it is used by railroad model builders and should be available at most hobby stores that carry paints for models. You want to get one of the "flat" (not gloss) colors because of the amount of solid particles that are mixed into the paint. I don't think the color matters much as long as it is a "flat" finish. BudP might have more to say on that tho -.
The conformal coating is made by Microscale Industries Inc. - http://www.microscale.com - and has properties similar to floor wax - but it is not floor wax - that was a description by BudP to describe some of it's physical properties - it is a conformal coating and it should be available at model shops as well.
Hope that this helps you!
I'm up a bit earlier than BudP because I'm in a different time zone and thus able to provide you with an answer a bit earlier due to the time difference.
The acrylic paint that BudP uses is made by a division Testors and is called Floquil - http://www.testors.com - it is used by railroad model builders and should be available at most hobby stores that carry paints for models. You want to get one of the "flat" (not gloss) colors because of the amount of solid particles that are mixed into the paint. I don't think the color matters much as long as it is a "flat" finish. BudP might have more to say on that tho -.
The conformal coating is made by Microscale Industries Inc. - http://www.microscale.com - and has properties similar to floor wax - but it is not floor wax - that was a description by BudP to describe some of it's physical properties - it is a conformal coating and it should be available at model shops as well.
Hope that this helps you!
Bud,
I think obtaining better designs really take lots of effort, and there are few people that really take steps necessary to do so. I am interested in communicating with people primary of this cartegory. People that study on their own, and may bring up subjects for discussion in order to obtain a better design. Gaining more recognition is not my primary goal. Many people discuss audio related issues either purely from an art point of view or purely from a theoretical point of view. While these may be good subjects to talk about, but normally do not get to the real guts of what's happening, and generally achieve nothing new. I think if people are serious enough about this, they will get the proper equipment, I started out with freeware (speaker workshop), a WM61 capsule for the mic, a $5 mic preamp, a $10 chip power amp, and basic computer hardware. This is not much. So when I see people take steps, then I will post appropriate information.
When I started out tuning drivers, I started out from an energy transmission and dissipation point of view which involves conflexure, and damping. Like you, I started playing around with different patterns and locations to find out whether general improvements can be made just from understanding and feeling of basic physics. Once I hit a sweet spot, then I did some measurements to see how it differed from the standard driver. Once I sorted out some trends, I started working on measurement of the different patterns to see how various tuning changed the measured data. Lots of these require experience to some sense to understand what I might explain. If people have not gone through the measurements, I can talk about lots of things and waste my time, and people still can't understand.
Concerning the phase lead issue, I played with one driver and added an outer pattern first, took a measurement, put on the inner pattern without removing the driver, and took another measurement. The major changes were in the phase response. I do not see this phase change alone to cause flattening of soundstage. If this phase change was caused by different motor design, then it would be a different issue.
Normally flattening in perceived space and instruments indicate that a different cone breakup mode or resonance is formed. You really need to look at measurement data to verify this.
Any new concepts or considerations that I may have missed in the past, I will explore to some degree. Idealy if I can find existing drivers that have the qualities that I am looking for, I will apply them to commercial designs. If modification of existing drivers work, then I will ask to see if driver suppliers can do some modification. If there are some processes the manufacturer cannot do, then I will find a way to get it done if possible. I am trying to develope good performance speakers, without making them too expensive. I believe this is possible with a little more care in the design and manufacturing process.
I think obtaining better designs really take lots of effort, and there are few people that really take steps necessary to do so. I am interested in communicating with people primary of this cartegory. People that study on their own, and may bring up subjects for discussion in order to obtain a better design. Gaining more recognition is not my primary goal. Many people discuss audio related issues either purely from an art point of view or purely from a theoretical point of view. While these may be good subjects to talk about, but normally do not get to the real guts of what's happening, and generally achieve nothing new. I think if people are serious enough about this, they will get the proper equipment, I started out with freeware (speaker workshop), a WM61 capsule for the mic, a $5 mic preamp, a $10 chip power amp, and basic computer hardware. This is not much. So when I see people take steps, then I will post appropriate information.
When I started out tuning drivers, I started out from an energy transmission and dissipation point of view which involves conflexure, and damping. Like you, I started playing around with different patterns and locations to find out whether general improvements can be made just from understanding and feeling of basic physics. Once I hit a sweet spot, then I did some measurements to see how it differed from the standard driver. Once I sorted out some trends, I started working on measurement of the different patterns to see how various tuning changed the measured data. Lots of these require experience to some sense to understand what I might explain. If people have not gone through the measurements, I can talk about lots of things and waste my time, and people still can't understand.
Concerning the phase lead issue, I played with one driver and added an outer pattern first, took a measurement, put on the inner pattern without removing the driver, and took another measurement. The major changes were in the phase response. I do not see this phase change alone to cause flattening of soundstage. If this phase change was caused by different motor design, then it would be a different issue.
Normally flattening in perceived space and instruments indicate that a different cone breakup mode or resonance is formed. You really need to look at measurement data to verify this.
Any new concepts or considerations that I may have missed in the past, I will explore to some degree. Idealy if I can find existing drivers that have the qualities that I am looking for, I will apply them to commercial designs. If modification of existing drivers work, then I will ask to see if driver suppliers can do some modification. If there are some processes the manufacturer cannot do, then I will find a way to get it done if possible. I am trying to develope good performance speakers, without making them too expensive. I believe this is possible with a little more care in the design and manufacturing process.
Fostex 127 E
I have finished applying the Micro Gloss coatings.
The main cone took three coats. All were applied with a 1/2 inch wide flat sable brush, full strength. It took 6 brush loads, each was a full bristle depth dip with both sides tamp drained. With a tamp drain off of a brush head you slide the brush up the end of the bottle neck while pushing lightly into that bottle edge and draining the excess back into the bottle.
The second coat was also full strength but took only four brush loads to accomplish. The brush strokes for both of these were from epoxy ring, between cone and dome to final edge, in a radial stroke.
The last coat was done with a 50% water / gloss coat mixture. I divided it into two sessions. The first half of the final coating had the brush moving in a circle, around the cone. This took three brush dips. The final coat was again applied in a radial direction and three brush dips were needed. Allow at least 4 hours after the first coat and 1 hour after each succeeding coating for the material to out gas.
The dome was done with one coat, split into two sessions. I used a 50 % mixture again and a thin fine tipped water color brush. Both coats were single brush dips, applied with minimal tamp draining and just sort of slathered on, without worry about a particular application pattern, just a general over brush until all of the material appeared to be evenly applied.
The sound, after a two hour period of out gassing, is crystal clear, with amazing sound stage and dispersion, just sitting on the floor, propped up on a 60 degree angle, no baffle. The speakers were easily able to throw a believable sound stage up to ear height and above, with a "huge" character to the sound. I expect them to be better than this tomorrow.
They have to be, because they will be on display for a possible meeting that might end up in a commercial venture to clear up the sound of all of those horrid talking books and dolls and tanks and other toys..... or not, who knows? But that would be an improvement in our in home environments... at least the ones with children still raising the dust up from the cracks between the floor boards!
Came about from a patent search too, but, considering the nature of Dame Fortune, this probably had to be given away first. Certainly almost no one has ever been interested before.
Bud
I have finished applying the Micro Gloss coatings.
The main cone took three coats. All were applied with a 1/2 inch wide flat sable brush, full strength. It took 6 brush loads, each was a full bristle depth dip with both sides tamp drained. With a tamp drain off of a brush head you slide the brush up the end of the bottle neck while pushing lightly into that bottle edge and draining the excess back into the bottle.
The second coat was also full strength but took only four brush loads to accomplish. The brush strokes for both of these were from epoxy ring, between cone and dome to final edge, in a radial stroke.
The last coat was done with a 50% water / gloss coat mixture. I divided it into two sessions. The first half of the final coating had the brush moving in a circle, around the cone. This took three brush dips. The final coat was again applied in a radial direction and three brush dips were needed. Allow at least 4 hours after the first coat and 1 hour after each succeeding coating for the material to out gas.
The dome was done with one coat, split into two sessions. I used a 50 % mixture again and a thin fine tipped water color brush. Both coats were single brush dips, applied with minimal tamp draining and just sort of slathered on, without worry about a particular application pattern, just a general over brush until all of the material appeared to be evenly applied.
The sound, after a two hour period of out gassing, is crystal clear, with amazing sound stage and dispersion, just sitting on the floor, propped up on a 60 degree angle, no baffle. The speakers were easily able to throw a believable sound stage up to ear height and above, with a "huge" character to the sound. I expect them to be better than this tomorrow.
They have to be, because they will be on display for a possible meeting that might end up in a commercial venture to clear up the sound of all of those horrid talking books and dolls and tanks and other toys..... or not, who knows? But that would be an improvement in our in home environments... at least the ones with children still raising the dust up from the cracks between the floor boards!
Came about from a patent search too, but, considering the nature of Dame Fortune, this probably had to be given away first. Certainly almost no one has ever been interested before.
Bud
BudP said:
plan as it currenty stands is that when Chris goes down to pick them up he will bring down a set of undrivered Fonkens and a pair with our standard driver. That will alu to listen tp both our drivers & the one you have just done up in boxes designed for them.
That should be very revealing.
dave
PS: Thanx Bud for doing this.
After reviewing data on the JX92S, I may spend some time to improve it using the EnABLE process. Anyhow, here is a reference picture resulting from a series of messing around. This does not indicate this is the solution, but just showing what options I added to see what changes occurs.
An externally hosted image should be here but it was not working when we last tested it.
Having printed out so much stuff form your site, I only recently started to catch up with this link. Lynn's " Beyond the Ariel " has now exceeded a ream.
Anyway on post " 43 ", Lynn mentions his " Progressive Loss Mesh ", on the front baffle, where perhaps thousannds of small holes are drilled out. It occured to me that a natural product may already exist, namily cork. This has been used on various speakers in the past, I pressume for cosmetic reasons. Tannoy used cork in the 70-80's, e.g, Balmoral - Devon, and looked very nice.
Cork, untreated, come in a variety of textures. If you look at say a close graine type, it comprises of a multitude of randomly shaped grains with many tiny holes between them. This may provide a similar " Loss Mesh "you discribed ( ? ) I have read that one cubic inch of cork consists of 200 milllion air cells measuring 1/1000 of an inch in diameter, try and drill that lot out !
There is an interesting link on, " www.audiotweaks.com / collection " , where Franco Lucignani discribes his use of cork on his front baffles which also provides the recess for flush mounting the drivers. He then goes on to say that it helps the speaker to " disappear "
He states that " the drivers seem to work with less interferance. The propagation of the sound wave on the baffle is quickly absorbed by the cork by the uneven surface that breaks up the wave front. " The sound wave boundry layer arrives spent on the corners, providing a more focussed sound stage ". He says he has seen this tweak on the " Yamaura Churchill horns ". externally and interernally.
I do not Know if the discription of the results is accurate or if cork would fulfill the " Loss Mesh " criteria, but I would be very interesed in Lynn,s and Buds comments.
Cork does have additional qualities, and is used extensivily for its sound deadening properties to reduse noise transmission in buildings etc. It seems to be overlooked in the diy speaker area. On last pair of speakers I built, though I stuck to veneer I did use Cork on the back panel. Using the highly scientifc method of " laying of hands " the vibrations always seemed quieter, so perhaps I should have covered the whole enclosure
Roy
Anyway on post " 43 ", Lynn mentions his " Progressive Loss Mesh ", on the front baffle, where perhaps thousannds of small holes are drilled out. It occured to me that a natural product may already exist, namily cork. This has been used on various speakers in the past, I pressume for cosmetic reasons. Tannoy used cork in the 70-80's, e.g, Balmoral - Devon, and looked very nice.
Cork, untreated, come in a variety of textures. If you look at say a close graine type, it comprises of a multitude of randomly shaped grains with many tiny holes between them. This may provide a similar " Loss Mesh "you discribed ( ? ) I have read that one cubic inch of cork consists of 200 milllion air cells measuring 1/1000 of an inch in diameter, try and drill that lot out !
There is an interesting link on, " www.audiotweaks.com / collection " , where Franco Lucignani discribes his use of cork on his front baffles which also provides the recess for flush mounting the drivers. He then goes on to say that it helps the speaker to " disappear "
He states that " the drivers seem to work with less interferance. The propagation of the sound wave on the baffle is quickly absorbed by the cork by the uneven surface that breaks up the wave front. " The sound wave boundry layer arrives spent on the corners, providing a more focussed sound stage ". He says he has seen this tweak on the " Yamaura Churchill horns ". externally and interernally.
I do not Know if the discription of the results is accurate or if cork would fulfill the " Loss Mesh " criteria, but I would be very interesed in Lynn,s and Buds comments.
Cork does have additional qualities, and is used extensivily for its sound deadening properties to reduse noise transmission in buildings etc. It seems to be overlooked in the diy speaker area. On last pair of speakers I built, though I stuck to veneer I did use Cork on the back panel. Using the highly scientifc method of " laying of hands " the vibrations always seemed quieter, so perhaps I should have covered the whole enclosure
Roy
Hi Roy,
I have sent an email to Lynn asking him to answer your questions, I am not competent to do more than guess. You might just copy the post to his Ariel thread, where all of the baffle board terminus options are being discussed. I'm afraid I just have one hammer, a very good one and one that works so well that I just have not explored other avenues.
Bud
I have sent an email to Lynn asking him to answer your questions, I am not competent to do more than guess. You might just copy the post to his Ariel thread, where all of the baffle board terminus options are being discussed. I'm afraid I just have one hammer, a very good one and one that works so well that I just have not explored other avenues.
Bud
LOWTHER
Ok, I think it must be time for some ugly secrets to escape.
Limono has had his drivers for two days now. His private email to me showed he was under quite a bit of stress. This is directly related to the EnABL process.
No, it isn't a secret nerve damaging sorcery. It is just way more information than he was ready for. With gallons of details he has never encountered and absolute precision and a glossy, ultra clear presentation that never lets up, absolutely relentless in it's presentation of ALL OF THE INFORMATION.
This includes all of the tweaks and tricks he has applied over the years to get his system to perform in a reputable way before EnABL came along. For all of you who have performed this process, just keep getting rid of "solutions" to problems you had before. You will likely end up with far more neutral, wide band cables everywhere. You will probably end up with many fewer or at least less highly Q'ed components in your signal chain and you may occasionally wish for just a bit less information, until you get your system flat and dead neutral.
Poor guy has a full on, completely polite speaker system. One even my wife called "without distortion in the mids and high end" and "without time related errors".
Now he has to un-peak his system so that the sibilants don't overwhelm and the transients are settled back down to a more normal activity. It is going to take him a while to remember all of the things he has done to help, prior to asking for the need for help to be removed.
He has my sympathy. it is what has driven me to invent adjustable dynamic color cables and dead neutral output transformers, interstage transformers and input splitter transformers. Fully EnABL'ed speakers are also what have driven me to a four stage amplification system, with one capacitor and eight grid blocker resistors in the signal path. Everything else is just relentlessly revealed.
Seriously, you are facing perhaps 10 times the information you have ever had and greatly enhanced high frequency dynamic performance. Once your system is reconfigured to neutral you will find that every alteration and increase in information is faithfully reproduced.
I expect him to post here when he feels confident. Please pay very careful attention to all that he says, it will become your problem too.
So, take my words as fair warning and his stress as real, you can be sure his threat correlator is on high alert and that is tiring.
Bud
Ok, I think it must be time for some ugly secrets to escape.
Limono has had his drivers for two days now. His private email to me showed he was under quite a bit of stress. This is directly related to the EnABL process.
No, it isn't a secret nerve damaging sorcery. It is just way more information than he was ready for. With gallons of details he has never encountered and absolute precision and a glossy, ultra clear presentation that never lets up, absolutely relentless in it's presentation of ALL OF THE INFORMATION.
This includes all of the tweaks and tricks he has applied over the years to get his system to perform in a reputable way before EnABL came along. For all of you who have performed this process, just keep getting rid of "solutions" to problems you had before. You will likely end up with far more neutral, wide band cables everywhere. You will probably end up with many fewer or at least less highly Q'ed components in your signal chain and you may occasionally wish for just a bit less information, until you get your system flat and dead neutral.
Poor guy has a full on, completely polite speaker system. One even my wife called "without distortion in the mids and high end" and "without time related errors".
Now he has to un-peak his system so that the sibilants don't overwhelm and the transients are settled back down to a more normal activity. It is going to take him a while to remember all of the things he has done to help, prior to asking for the need for help to be removed.
He has my sympathy. it is what has driven me to invent adjustable dynamic color cables and dead neutral output transformers, interstage transformers and input splitter transformers. Fully EnABL'ed speakers are also what have driven me to a four stage amplification system, with one capacitor and eight grid blocker resistors in the signal path. Everything else is just relentlessly revealed.
Seriously, you are facing perhaps 10 times the information you have ever had and greatly enhanced high frequency dynamic performance. Once your system is reconfigured to neutral you will find that every alteration and increase in information is faithfully reproduced.
I expect him to post here when he feels confident. Please pay very careful attention to all that he says, it will become your problem too.
So, take my words as fair warning and his stress as real, you can be sure his threat correlator is on high alert and that is tiring.
Bud
From some experience on other drivers using boundary layer control techniques. One needs to be aware that each driver will require tuning so that the phase and frequency response are very close. If one driver leads in phase by more than 10 degrees, then you will hear some sort of imbalance with the image shifted slightly to one side.
Here are some SoundEasy measurement results of the JX92S with the MLS window starting at 86.717cm.
I am convinced if the cone breakup close to 12KHz is taken care of, then the JX92S will sound really smooth and clean. This breakup is probably the slight roughness that most people hear with the JX92S.
So if I can slip some time in, I'll try to tune the JX92S, and send it to someone already using the same driver as full range to see how they compare.
Here are some SoundEasy measurement results of the JX92S with the MLS window starting at 86.717cm.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
I am convinced if the cone breakup close to 12KHz is taken care of, then the JX92S will sound really smooth and clean. This breakup is probably the slight roughness that most people hear with the JX92S.
So if I can slip some time in, I'll try to tune the JX92S, and send it to someone already using the same driver as full range to see how they compare.
Cork
My impression is the cork and array of holes at the edge of the baffle would be complementary, since they do different things. Sound doesn't go through cork so much as get absorbed by it - and I would surmise much of the absorption would be at higher frequencies.
The scores or hundreds of randomly-drilled holes (not thousands) in a progressive-loss mesh are intended to provide a resistive path from the front to the rear of the baffle (through holes that are smaller than the shortest wavelength of interest). Air doesn't pass quite so readily through cork, otherwise it would be useless for wine bottles! I think most of the cells of cork are closed, not open, so air passes through rather slowly.
That said, cork would make a visually interesting and acoustically absorptive baffle covering, on both front and rear sides of a rigid baffle. It would definitely be useful to cover the exterior of the HF horn, so sound from the widerange driver directly beneath it wouldn't reflect off the outer surface. If you were really adventurous, you could put a thin layer of cork *inside* the horn, and see how that affected the impulse, frequency response, and directivity.
If a thin layer of cork was placed over the holes of the progressive-loss mesh, I don't know what it would do - alter the behaviour of the mesh in some way, I just don't know in what kind of way. You'd have to determine this by measurement and audition.
Roy Lewis said:
My impression is the cork and array of holes at the edge of the baffle would be complementary, since they do different things. Sound doesn't go through cork so much as get absorbed by it - and I would surmise much of the absorption would be at higher frequencies.
The scores or hundreds of randomly-drilled holes (not thousands) in a progressive-loss mesh are intended to provide a resistive path from the front to the rear of the baffle (through holes that are smaller than the shortest wavelength of interest). Air doesn't pass quite so readily through cork, otherwise it would be useless for wine bottles! I think most of the cells of cork are closed, not open, so air passes through rather slowly.
That said, cork would make a visually interesting and acoustically absorptive baffle covering, on both front and rear sides of a rigid baffle. It would definitely be useful to cover the exterior of the HF horn, so sound from the widerange driver directly beneath it wouldn't reflect off the outer surface. If you were really adventurous, you could put a thin layer of cork *inside* the horn, and see how that affected the impulse, frequency response, and directivity.
If a thin layer of cork was placed over the holes of the progressive-loss mesh, I don't know what it would do - alter the behaviour of the mesh in some way, I just don't know in what kind of way. You'd have to determine this by measurement and audition.
Lynn,
Thanks, very clear answer, I wonder what happens if we drill holes in the cork glued to the edge area of the baffle? Especially if the cork was sunk to the height of the rest of the baffle.
Sonngsc,
Those are quite nice CSD plots!!!. I am captivated by the phase control in the high frequencies. I wonder what physical parameter determines where that change begins in the bandwidth. There is a very small difference in mid frequencies too, but that top end alteration is very intriguing. It has to be related to driver geometry and perhaps to details of pattern ring placement.
I also note that as each ring is applied the amount of time it takes the energy to decay is reduced by a small percentage but the overall frequency response does not seem to change at impulse and sustain. Plus the sustain band, from untreated to all pattern rings applied gets noticeably narrower, indicating quite a bit better decay structures, so ever better refinement in imaging and greater transparency. I think this will cause me to have to take up experimentation once again, to see if what you have discovered is as audible as it seems it must be. And, just what these measured changes bring to transparency and reveal of tonal emphasis. The more I look at these plots the more excited I get.
Thank you for posting these. This really is a validation of thirty years worth of blundering around trying to think my way through the problems.. I am just delighted.
Bud
Thanks, very clear answer, I wonder what happens if we drill holes in the cork glued to the edge area of the baffle? Especially if the cork was sunk to the height of the rest of the baffle.
Sonngsc,
Those are quite nice CSD plots!!!. I am captivated by the phase control in the high frequencies. I wonder what physical parameter determines where that change begins in the bandwidth. There is a very small difference in mid frequencies too, but that top end alteration is very intriguing. It has to be related to driver geometry and perhaps to details of pattern ring placement.
I also note that as each ring is applied the amount of time it takes the energy to decay is reduced by a small percentage but the overall frequency response does not seem to change at impulse and sustain. Plus the sustain band, from untreated to all pattern rings applied gets noticeably narrower, indicating quite a bit better decay structures, so ever better refinement in imaging and greater transparency. I think this will cause me to have to take up experimentation once again, to see if what you have discovered is as audible as it seems it must be. And, just what these measured changes bring to transparency and reveal of tonal emphasis. The more I look at these plots the more excited I get.
Thank you for posting these. This really is a validation of thirty years worth of blundering around trying to think my way through the problems.. I am just delighted.
Bud
Bud,
I normally tend to think in terms of energy. Whatever we do to the cone we think of how energy is tranferred and dissipated. So there are just too many factors that come into consideration to explain in a forum, and way beyond what most readers can comprehend. The plots really tell most of the story. Lots of people deal with equations etc. But without understanding and feeling for the functionality of things, equations can be wrongly applied. Klippel has a good cone related paper when they talk about their cone vibration module.
After some time in various forums, I like to present where information can be found, and let others study on their own.
I normally tend to think in terms of energy. Whatever we do to the cone we think of how energy is tranferred and dissipated. So there are just too many factors that come into consideration to explain in a forum, and way beyond what most readers can comprehend. The plots really tell most of the story. Lots of people deal with equations etc. But without understanding and feeling for the functionality of things, equations can be wrongly applied. Klippel has a good cone related paper when they talk about their cone vibration module.
After some time in various forums, I like to present where information can be found, and let others study on their own.
I posted this with an intention to show that while most people say that phase can be extracted using some sort of linear transform, in reality, you can see that even though the shape of the response does not change much, the phase changes quite noticebly. Where this change occurs depends on too many factors, especially for wide range drivers. In wide range drivers, the most difficult area to control is beyond 10KHz. One will be lucky to get two drivers that match well in this region for wide range drivers. but if you tune them to match, then the results are awesome.BudP said:
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