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Old 3rd December 2012, 12:03 AM   #301
iko is offline iko  Canada
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Originally Posted by planet10 View Post
I was/would be very interested in how you get along if you proceed
dave
I still think I'll do it. But I'm not used to be so much in the dark regarding the design. If it becomes clearer how the B200 fit in the 4x4 boards then I'll go ahead with it.

Meanwhile I think I might give it a try and build something that's been done here already.
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Old 3rd December 2012, 12:07 AM   #302
xrk971 is offline xrk971  United States
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Originally Posted by Cal Weldon View Post
OK, so I added a little stuffing to the throats and that really helped with the bass horny hump above 100 Hz. I also placed them 12" away from the wall and that was another plus. I am thinking that further stuffing of the throats and returning them closer to the wall will be the cat's meow. I'll find out another day as I have to wrap it up but the improvements were huge, heck even SWMBO took an interest which is almost unheard of. I listened to my regular test tunes and then I put on Jimmy...

That's where I've been for the last couple hours.

I don't know what to say, I'm near speechless. For those who know me that's something they wouldn't believe for a second.

Cheers.
So it's not just me thinking that the sound from these spirals is unlike anything else and amazing? I'm glad you like them. I put some high quality classical recordings through them and trios and quartets and chamber stuff sound amazing. The track slow like honey by Fiona Apple is just unbelievable. SWMBO finally came down to the rec room and she said they sounded really good and much bigger than they look.

Last edited by xrk971; 3rd December 2012 at 12:09 AM.
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Old 3rd December 2012, 12:25 AM   #303
xrk971 is offline xrk971  United States
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Originally Posted by planet10 View Post
There is a relation between Vas, Q, volume of the air cavity, and the throat area that determine the low pass function. Youdon't want too much HF coming out the horn mouth

Further. the difference in path length between the direct radiation and that from the back of the driver to your ear should be an odd number of half wavelengths of the nominal f3 of the acoustic LP of the throat/air cavity.

Efficiency (horn gain) is not high on the list of parameters to design for -- more of interest in front horns. Cal's build ilustrate that as long as you have enuff or more than you need horn gain can be adjusted with stuffing. You want the fall-off of the driver & baffle-step losses to be compensated for by the gain of the horn. With no baffle steptodeal with this horn needs less gain, the big bonuses coming from the ability to get lower bass out of asmall driver, and reduction in excursion at those frequencies.

dave
I got read up on this theory - do you have a good reference that describes the equation which you speak of? However, I purposely put sharp turns on the inner passages of my design to filter and low pass the horn output.
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Old 3rd December 2012, 12:42 AM   #304
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Originally Posted by xrk971 View Post
For portable stereo sound, try the simple one fold wall hanging transmission line mentioned earlier in this thread but scale it down. It sounds very good with super bass extension and a nice even round feeling that everything is all there. To make more compact, maybe fold it three times but keep it fairly flat circa 2.5 to 3 inches. Check out Cal's sig line in his projects he has several portable speaker systems. My fav is the Pentagon tower with 5 sides each with what looks like 3 in drivers and a tweeter with the amp inside the tower. Not sure how he manages stereo with 5 sides???


thanks for the input. basically, stereo isnt an issue for my laptop, just as long as both signals are present. as far as laptop sound goes, i also produce dance music, so kinda need a bit of kick to the sound for when i occasionally want to produce something on-the-run.. beyond that, its mostly for times when im playing a basic setlist (im also a mobile DJ) for friends at small friendly gatherings. so need somewhat decent volume as well.

generally speaking, since sealing my little horn, it sounds so much better than what i had just sitting on the carpet. (that you were spot on about! and i kinda knew in the back of my mind as well) but, doesnt quite have the low bass extension that im looking for.

the new horn design (according to your maths) @~1meter extends to 85hz, which still i think isnt enough, so ill redraw again and see if i can get more length. i think even another 25-35cm will get me into the 60hz range. (good luck with that hey... lol)

as for the computer inside the house, id love a set of reference speakers for doing mastering edits on. i have a small range of different speakers i could utilise for this. ill post up when im ready.
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Old 3rd December 2012, 12:48 AM   #305
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Originally Posted by xrk971 View Post
she said they sounded really good and much bigger than they look.
Bingo.
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Old 3rd December 2012, 12:56 AM   #306
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OT for the moment.

xrk, because you showed an interest, the Pentagon is a bi-amped dual chamber system with 6.5" woofer on the bottom and the 2X3" + tweeter in the front.
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Old 3rd December 2012, 01:04 AM   #307
xrk971 is offline xrk971  United States
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Originally Posted by klampykixx View Post
thanks for the input. basically, stereo isnt an issue for my laptop, just as long as both signals are present. as far as laptop sound goes, i also produce dance music, so kinda need a bit of kick to the sound for when i occasionally want to produce something on-the-run.. beyond that, its mostly for times when im playing a basic setlist (im also a mobile DJ) for friends at small friendly gatherings. so need somewhat decent volume as well.

generally speaking, since sealing my little horn, it sounds so much better than what i had just sitting on the carpet. (that you were spot on about! and i kinda knew in the back of my mind as well) but, doesnt quite have the low bass extension that im looking for.

the new horn design (according to your maths) @~1meter extends to 85hz, which still i think isnt enough, so ill redraw again and see if i can get more length. i think even another 25-35cm will get me into the 60hz range. (good luck with that hey... lol)

as for the computer inside the house, id love a set of reference speakers for doing mastering edits on. i have a small range of different speakers i could utilise for this. ill post up when im ready.
Klampykixx,
If you only have 1 meter, make a mass loaded transmission line rather than horn. You can reach down to 55 Hz easily by constricting the exit port (opposite of a horn) and stuffing the first 2/3 of the line densely. It helps to have a driver with high Qts to do this, read Bjorn Johanessen's TABAQ thread and you will see the performance that can be achieved with limited path length. If you don't need stereo, place both left and right drivers right net to each other at the 1/3 (from closed end), double the cross section and vent area and you should have it. Bjorn recommends that the cross sectional area of the transmission line be 4x the Sd. For two 3 in drivers, make the cross sectional area about 40 square inches x 36 inches long. See post 268 in this thread to get an idea. TABAQ TL for Tang Band.
Regards,
Xrk971

Last edited by xrk971; 3rd December 2012 at 01:10 AM.
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Old 3rd December 2012, 01:05 AM   #308
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I just checked the local dolllar store. No foamboard. Michael's (on theotherside of the grocery store has 20x30" for $5 a sheet, 2x for ones with flat colour or some patterns including glittery metallic.

Each sheet good for 4 4.5" wide 30" strips.

CAD program says the short sporals are 1585mm (62.4"), the long ones 2234mm (88") so total of 7.638m = 301"

9 strips for the short, 12 for the long, 6 sheets = $30, $10 more for a colour or patterned board in the exit area.

I'll continue to check other stores.

dave
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Old 3rd December 2012, 01:08 AM   #309
xrk971 is offline xrk971  United States
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Quote:
Originally Posted by Cal Weldon View Post
OT for the moment.

xrk, because you showed an interest, the Pentagon is a bi-amped dual chamber system with 6.5" woofer on the bottom and the 2X3" + tweeter in the front.
Very cool, I thought you had drivers on all five sides for an omnidirectional deal, so couldn't figure out how to do stereo on that. What 3 in driver did you use?
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Old 3rd December 2012, 01:09 AM   #310
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Originally Posted by ikoflexer View Post
I still think I'll do it. But I'm not used to be so much in the dark regarding the design. If it becomes clearer how the B200 fit in the 4x4 boards then I'll go ahead with it.

Meanwhile I think I might give it a try and build something that's been done here already.
This thread has shown how to build these quickly and cheaply. Chris tells me it easier to build and try than futz around with the theory sometimes. That has already successfully been done twice in this thread.

And if the B200 does't work out, you can try other drivers.

dave
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