Good reply's guys.
Carpenter, the problem with OB is not covering, it's having to move them so far from the walls to get good sound. I like OB sound. Just don't want to have to move them around constantly.
Zobsky, I looked into the Selah Symetrica. The thing I'm trying to get around with what I asked about earlier is the driver spacing Vs. wavelength problem. Steve Slater turned me on to your thread when I asked him about the cheapie Apex tweeters. as it stands now if I by the closeout 5.25" drivers, I pretty much have to roll my crossover in the low to mid 2k range, according to your tests the tweeters roll off pretty steeply at 3k. My hope was to not imitate the JBL style like Selah, but to double up the woofer line with a 1/2 offset to try and raise the level that comb lining begins. I whipped up a sketchup drawing only to illustrate what I'm thinking of.
If the Two lines will act as a point source, then I have reduced my spacing from 5.25" to 2.625"
John
Carpenter, the problem with OB is not covering, it's having to move them so far from the walls to get good sound. I like OB sound. Just don't want to have to move them around constantly.
Zobsky, I looked into the Selah Symetrica. The thing I'm trying to get around with what I asked about earlier is the driver spacing Vs. wavelength problem. Steve Slater turned me on to your thread when I asked him about the cheapie Apex tweeters. as it stands now if I by the closeout 5.25" drivers, I pretty much have to roll my crossover in the low to mid 2k range, according to your tests the tweeters roll off pretty steeply at 3k. My hope was to not imitate the JBL style like Selah, but to double up the woofer line with a 1/2 offset to try and raise the level that comb lining begins. I whipped up a sketchup drawing only to illustrate what I'm thinking of.
If the Two lines will act as a point source, then I have reduced my spacing from 5.25" to 2.625"
John
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zobsky said:
Plan is to put these in the far corners next to the roll up doors, my workbench and the area I usually utilize for projects is between 12 and 24 feet away
John
Great drawing! Do it. 🙂
With regards to OB in your work space, I've been hammering out an idea that may be of interest:
The 18" tapped horn is about 36 inches on the diagonal. I'm going to set the line array above the tapped horn's port and let the rear radiation from the array reflect against the horn. It should bounce to the adjacent walls and back towards the front of the baffle. I can adjust my wings forward if required.
With regards to OB in your work space, I've been hammering out an idea that may be of interest:
The 18" tapped horn is about 36 inches on the diagonal. I'm going to set the line array above the tapped horn's port and let the rear radiation from the array reflect against the horn. It should bounce to the adjacent walls and back towards the front of the baffle. I can adjust my wings forward if required.
Attachments
mightym said:
Disclaimer: I don't really know nothin about nothin. This is just some stuff I made up that sounds like it might be true.
I'm guessing that the two lines will only act like a single line up as far as... the line of individual drivers acts like the initial line. That is to say, only to 5.25" wavelength (~2.5 khz sez MM). The same logic that dictates when the individuals act as a line will dictate if the two lines act as one. Above that, you'll start inducing an interference pattern in the horizontal plane. But what do I know?
Are y'all running your line arrays full range, or do you low-pass 'em? I was planning to run mine full open.
In other news, I'm getting prepped to run my 20 examples of these woofers through my dayton woofer tester. I'll post about it when I'm done... The OB-LA shouldn't need the numbers, but it would be nice to see 'em, and I may make something else with a few extras.
AdamThorne said:
Do post at least some of your results, since those are the drivers I intend to use too.
BTW what did the shipping run on those?
John
mightym said:
I'm looking forward to checking the impedance sweep for any oddities. New Baby makes it hard to do anything quickly, but I'll throw up the results when I got 'em.
mightym said:
'bout $15, cheapest option. Looks like a carton = 24 drivers.
AdamThorne said:
Congrats on the new baby!
I should see 24 of those India drivers today. Along with a few other things $22 shipping to Southern Maine. Not bad.
Well, I've been saved from a lot of work and disappointment.
I was still wondering about the effects of adding a second line of woofers, only offset vertically 1/2 Dia. and whether this would sum to the line source or not.
I wasn't willing to experiment without at least some confidence that it would work.
I sought out someone who builds, and sells Line arrays. When I put the question to him, his response was short and to the point, I would only be adding another line of drivers which would add more lobing issues.
So, I now need to find another Tweeter that can be effectively crossed in at 2.5K or less, or reduce woofer diameter.
I hope that this does not discourage anyone, it didn't me. Just need to back up and re think the problem.
Anyone know of a cheap small tweeter comfortable with a 2K crossover out there, preferably with a fairly high efficiency?
John
I was still wondering about the effects of adding a second line of woofers, only offset vertically 1/2 Dia. and whether this would sum to the line source or not.
I wasn't willing to experiment without at least some confidence that it would work.
I sought out someone who builds, and sells Line arrays. When I put the question to him, his response was short and to the point, I would only be adding another line of drivers which would add more lobing issues.
So, I now need to find another Tweeter that can be effectively crossed in at 2.5K or less, or reduce woofer diameter.
I hope that this does not discourage anyone, it didn't me. Just need to back up and re think the problem.
Anyone know of a cheap small tweeter comfortable with a 2K crossover out there, preferably with a fairly high efficiency?
John
I bought the cheapest piezo PE had to go with these drivers, just to experiment with. But after thinking about it for a while I think I would be tempted to go with either
http://www.parts-express.com/pe/showdetl.cfm?Partnumber=272-104
or
http://www.parts-express.com/pe/showdetl.cfm?Partnumber=270-050
http://www.parts-express.com/pe/showdetl.cfm?Partnumber=272-104
or
http://www.parts-express.com/pe/showdetl.cfm?Partnumber=270-050
I did a little looking around this AM before I went to work, I'm leaning toward this one:
www.parts-express.com/pe/showdetl.cfm?Partnumber=272-115
It has more efficiency than I think I'll need, not knowing how much woofer efficiency is lost if the notch filter is used. I calculated that a 16 driver per side array would yield 103Db/1W if wired to 4 Ohm final impedance. Since the use of a single Tweeter per side will loose 6Db per doubling of distance, whereas the line will loose only 3Db (nearfield) , the efficiency miss-match can be adjusted to your listening position with an L-Pad. I have no experience with these tweeters, but they were well reviewed. They also seemed like a fair guess at $ for SQ without breaking the project.
I'm curious to know what the notch filter looks like, The one they sell to go with the buyout drivers ( in the related items tab on the driver's page ) lists components (a cap, inductor, and resistor ) but I can't recall the values right now.
John
www.parts-express.com/pe/showdetl.cfm?Partnumber=272-115
It has more efficiency than I think I'll need, not knowing how much woofer efficiency is lost if the notch filter is used. I calculated that a 16 driver per side array would yield 103Db/1W if wired to 4 Ohm final impedance. Since the use of a single Tweeter per side will loose 6Db per doubling of distance, whereas the line will loose only 3Db (nearfield) , the efficiency miss-match can be adjusted to your listening position with an L-Pad. I have no experience with these tweeters, but they were well reviewed. They also seemed like a fair guess at $ for SQ without breaking the project.
I'm curious to know what the notch filter looks like, The one they sell to go with the buyout drivers ( in the related items tab on the driver's page ) lists components (a cap, inductor, and resistor ) but I can't recall the values right now.
John
Carpenter, do you have the model nomenclature for the driver used in your bass horn?
IIRC you said it was a Mach 5 18"?
I wanted to plug your horn into Hornresp and play with it, try to scale it down to a 10-12" driver.
John
BTW in your illustration your show the Line Array placed in front of the bass horn, but with the wings apparently facing forward? am I misinterpreting the diagram?
IIRC you said it was a Mach 5 18"?
I wanted to plug your horn into Hornresp and play with it, try to scale it down to a 10-12" driver.
John
BTW in your illustration your show the Line Array placed in front of the bass horn, but with the wings apparently facing forward? am I misinterpreting the diagram?
There are a few details you may want to know--feel free to ask.
Yes, the 18" driver is a Mach 5 unit.
Yes, the 18" driver is a Mach 5 unit.
Audio Circle has a whole section on Line Arrays in the archives, that circle died about a year ago, is much good info there including projects by Zobsky!
John
John
Not wanting to jack this thread entirely, I started a different one for discussion of those cheapo peerless drivers, if any of you guys are interested...
http://www.diyaudio.com/forums/showthread.php?s=&threadid=141832
http://www.diyaudio.com/forums/showthread.php?s=&threadid=141832
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