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Old 23rd March 2007, 04:19 PM   #101
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Thomas,

What happens if you change the shape of a EnABL rectangular patch to a perfectly round circular shape, the pattern layout and spacing otherwise identical?
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Old 23rd March 2007, 04:41 PM   #102
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mamboni asked this in post #94 and BudP responded in post #96. It's Bud's idea and pattern so I don't want to speak for him out of my respect for his research and knowledge of his EnABL pattern. Heck - BudP holds the patent - so input from him is good as it can get!

One sure way to find out - go do it!!

If the round blocks don't work they will make good markers for where you want to place the squares - so no harm done. I wouldn't try it out on your favorite $500.00 super speakers until I had done a little learning on the Pioneer speaker that mamboni recommends. It's a $45.00 speaker that has been proven to work with his felt triangles.



Thomas

BTW - I just got my funding request approved by my higher authority (Spousal Unit) so I'm ordering speakers and looking for a local source of SonoTube. YEA!!!
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Old 23rd March 2007, 04:46 PM   #103
BudP is offline BudP  United States
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Utopix,

Sorry, I was so tired last night that I did not notice how far I had strayed from your idea, until this morning, when I awoke from a dream about being lectured for short sightedness.

The one piece panel that you are talking about will work. I suspect it needs to be made from vinyl and might best be made with a sign makers vinyl cutting machine. although I have never even seen one of these to know if it will cut rectangles in the middle of a space, rather than have it slice to the spot and then cut the rectangle.

I am willing to provide a specific pattern size for you to experiment with. Because of the number of times that you will have to peel and reattach you may need more than one application of the 3M tack adhesive Thomas was talking about.

Again I apologize for stomping all over your idea last night, I will probably do it again though.

Bud
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Old 23rd March 2007, 05:33 PM   #104
BudP is offline BudP  United States
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rcavictim,

I did perform an ad hoc wave tank test many years ago, and made simple line drawings of the results. If you would like to analyze them I will dig them up and put them into a pdf for you to look at. I will caution you that the effect they portray caused my high energy physicist friend who witnessed them, to claim they were the same as magic... something happening in front of his eyes that he not only did not understand but could not believe he was seeing.

A short description is a set of blocks, meaning two from one ring and a center set from the adjacent ring were cut from two pieces of 3/8" thick wood, as fingers sticking out from the edge about 1/2 inch. In other words every thing but the fingers was cut away and the resultant blocks followed the pattern array dimensions shown in the patent.

These block holders were sized to fit stiffly between the narrow walls of a 8 inch by 4 foot fish tank, half filled with water, about 6 inches deep Fluorescent lights were positioned underneath, lengthwise, and a piece of white cardboard was hung a couple of feet above the tank, to show the shadows of any wave action in the tank. A 6 inch wide dipping paddle was used to agitate the water at one end of the tank and the pattern holders were positioned six inches away from the dipping end of the tank, with the fingers into the water about a quarter of an inch. I make no claims about scientific rigor being used here, I just wanted some idea of what the heck was going on!

When the dipper was agitated, mostly up and down, without the pattern blocks pushed down into the water the expected choppy surface with waves that eventually became quite chaotic in direction arose after a few moments of agitation and took a few tens of seconds to completely dissipate and allow the water to become calm again.

When the pattern was shoved into the water that quarter inch and the dipper agitation restarted, a checkerboard pattern arose between the pattern and the dipper and from the other side, seemingly in perfect sync with each of the dipper strokes, a smooth, straight line of wave appeared from the pattern edge shadow, flowed to the end of the tank and dissipated without any obvious reflections. This pattern of activity held until you stopped dipping and the last wave occurred with the last dipper stroke and the water surface quickly became calm again.

All of this was clearly shown on the white cardboard surface as shadows. There was a pretty wide range of dipping cycle speeds that provided this effect, as the dipping was done by hand. I did not explore the out of range effects at the time so I cannot report on the failure modes.

Round pattern dots work fine, down to about 4 kHz and out to beyond my ability to measure. Below this vague cut off point the square edged shape begins to become necessary, though these "square" edged blocks usually are not all that square edged, but definitely not round either. I am quite certain, through some experimentation, that many "shapes" will work, some better than others at certain frequency ranges on certain materials, other than paper.

The rectangular in spirit blocks seem to work across the frequency band though at this late date I no longer try to make rectangular shapes on small high frequency drivers. Round dots, thankfully, work here very well. In fact I just treated a set of Pioneer piezio electric film tweeter to use to top off the high frequencies from the Radio Shack Linnaeum, baby cheek, soft horn wall tweeters I use. These only provide signal out to 13 kHz and the Pioneer half round "can" shaped devices are on a 0.22 mfd induced slope to match and extend out to 30 kHz or so..

Bud
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Old 23rd March 2007, 06:13 PM   #105
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Hi Mamboni!

I have the Pioneer speakers on order along with the caps and resistors and adhesive as per your spec's.

I have located some sources for felt but then I realized that I'm not sure exactly what type of felt I'm looking for!

Are there any guide lines as to thickness or density? From your photo's I'm guessing about a 1/4 inch (6 mm) thickness of medium density was used. Is the type of felt used critical?

Thank You!

Thomas
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Old 24th March 2007, 12:10 AM   #106
Utopix is offline Utopix  Canada
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Quote:
Originally posted by BudP
Utopix,

Sorry, I was so tired last night that I did not notice how far I had strayed from your idea, until this morning, when I awoke from a dream about being lectured for short sightedness.

The one piece panel that you are talking about will work. I suspect it needs to be made from vinyl and might best be made with a sign makers vinyl cutting machine. although I have never even seen one of these to know if it will cut rectangles in the middle of a space, rather than have it slice to the spot and then cut the rectangle.

I am willing to provide a specific pattern size for you to experiment with. Because of the number of times that you will have to peel and reattach you may need more than one application of the 3M tack adhesive Thomas was talking about.

Again I apologize for stomping all over your idea last night, I will probably do it again though.

Bud
BudP

I was just reading your first post and on this subjet and I was feeling that something was not clear. Sometimes its my writing that is not enough precise (English is not my first language) . Now,I think that we are in sync.

Thanks for your offer for providing some test pattern for me to experiment with. I will definitively come back to you on this subject in approx. 2 months. I have in front of me some major renovation project at my place and I feel that all my weekends will be spent on this. But beware, my interest in this topic is growing each and every day. Maybe I will be able to make some Sonotube enclosure before the end of April and be ready before May hopefully.

Cheers

Utopix.
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Old 24th March 2007, 03:35 AM   #107
mamboni is offline mamboni  United States
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Quote:
Originally posted by c2cthomas
Hi Mamboni!

I have the Pioneer speakers on order along with the caps and resistors and adhesive as per your spec's.

I have located some sources for felt but then I realized that I'm not sure exactly what type of felt I'm looking for!

Are there any guide lines as to thickness or density? From your photo's I'm guessing about a 1/4 inch (6 mm) thickness of medium density was used. Is the type of felt used critical?

Thank You!

Thomas
I used standard felt cloth that is used in craft projects. You can buy it by the yard at Kmart or Fabric Barn. The same felt goes by the name Kunin felt. It's about 2mm thick by eye, as thick as a nickel. But, I don't think the exact thickness is critical - my guess is that there is a lot of play in how much damping is required to render the woofer cone non-resonant. 6mm sounds like very thick felt - more than you need.
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Old 24th March 2007, 03:45 AM   #108
mamboni is offline mamboni  United States
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Quote:
Originally posted by BudP
rcavictim,

I did perform an ad hoc wave tank test many years ago, and made simple line drawings of the results. If you would like to analyze them I will dig them up and put them into a pdf for you to look at. I will caution you that the effect they portray caused my high energy physicist friend who witnessed them, to claim they were the same as magic... something happening in front of his eyes that he not only did not understand but could not believe he was seeing.

A short description is a set of blocks, meaning two from one ring and a center set from the adjacent ring were cut from two pieces of 3/8" thick wood, as fingers sticking out from the edge about 1/2 inch. In other words every thing but the fingers was cut away and the resultant blocks followed the pattern array dimensions shown in the patent.

These block holders were sized to fit stiffly between the narrow walls of a 8 inch by 4 foot fish tank, half filled with water, about 6 inches deep Fluorescent lights were positioned underneath, lengthwise, and a piece of white cardboard was hung a couple of feet above the tank, to show the shadows of any wave action in the tank. A 6 inch wide dipping paddle was used to agitate the water at one end of the tank and the pattern holders were positioned six inches away from the dipping end of the tank, with the fingers into the water about a quarter of an inch. I make no claims about scientific rigor being used here, I just wanted some idea of what the heck was going on!

When the dipper was agitated, mostly up and down, without the pattern blocks pushed down into the water the expected choppy surface with waves that eventually became quite chaotic in direction arose after a few moments of agitation and took a few tens of seconds to completely dissipate and allow the water to become calm again.

When the pattern was shoved into the water that quarter inch and the dipper agitation restarted, a checkerboard pattern arose between the pattern and the dipper and from the other side, seemingly in perfect sync with each of the dipper strokes, a smooth, straight line of wave appeared from the pattern edge shadow, flowed to the end of the tank and dissipated without any obvious reflections. This pattern of activity held until you stopped dipping and the last wave occurred with the last dipper stroke and the water surface quickly became calm again.

All of this was clearly shown on the white cardboard surface as shadows. There was a pretty wide range of dipping cycle speeds that provided this effect, as the dipping was done by hand. I did not explore the out of range effects at the time so I cannot report on the failure modes.

Round pattern dots work fine, down to about 4 kHz and out to beyond my ability to measure. Below this vague cut off point the square edged shape begins to become necessary, though these "square" edged blocks usually are not all that square edged, but definitely not round either. I am quite certain, through some experimentation, that many "shapes" will work, some better than others at certain frequency ranges on certain materials, other than paper.

The rectangular in spirit blocks seem to work across the frequency band though at this late date I no longer try to make rectangular shapes on small high frequency drivers. Round dots, thankfully, work here very well. In fact I just treated a set of Pioneer piezio electric film tweeter to use to top off the high frequencies from the Radio Shack Linnaeum, baby cheek, soft horn wall tweeters I use. These only provide signal out to 13 kHz and the Pioneer half round "can" shaped devices are on a 0.22 mfd induced slope to match and extend out to 30 kHz or so..

Bud
Bud:

It sounds like the blocks are acting as an interferometer or diffraction grid. I wish you had some photos - sounds fascinating. The ideal way to eliminate resonance is to introduce controlled destructive interference, a no efficiency-killing mass need be used.
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Old 24th March 2007, 03:48 AM   #109
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Hi Mamboni -

I resorted to consulting with a shopping expert ----- that being my spousal unit.

It took her almost 2 nanoseconds to say the crafts section at WalMart!

Go Figure

Parts should be here in about a week - located a local source for Sonotube - which was more difficult than I thought and I finally wound up calling Sonotube to get hold of a local distributer. The 14 inch size I want to use is not a common item. 12 inch and 16 inch are common tho -



Thomas
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Old 24th March 2007, 05:17 AM   #110
BudP is offline BudP  United States
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Mamboni,

I have always thought of them as a diffraction grating, but working with a vertical vector that is unusual in ordinary wave tank experiments, so, I had to modify my thinking just a bit.

We are both involved in this same process and using effectively the same tools, just arrayed differently and applied with different measures, same thoughts though. I am pretty sure that a combination of the two, along with treating both sides of the dome tweeter diaphragms with EnABL, will take your current 90% of the ohm model 5's performance and turn it into about 180%

I too wish I had some pictures of this earlier time in my life, especially one of Bill's face, the physicist friend, to show to you, when I asked him what he thought was going on.... a priceless memory I will carry to my grave.

Bud
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