Simple! [message #45745 is a reply to message #45732] |
Sat, 06 November 2004 02:56 ![Go to previous message Go to previous message](/forum/theme/AudioRoundTable/images/up.png) ![Go to next message Go to next message](/forum/theme/AudioRoundTable/images/down.png) |
Mike.e
Messages: 471 Registered: May 2009
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Illuminati (1st Degree) |
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Simple concept! I heard of John doing this on a certain basshorn-but didnt see how it was implemented I think that if the Vtc,and Vrc are similar and not too different the loading will be equal. (infact perhaps the loading wont change just the individual horn parameters) -off to town to hear 1" HF horn + 15" and quiet bass! Regards Mike.e
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Re: Simple! [message #45746 is a reply to message #45745] |
Sat, 06 November 2004 02:58 ![Go to previous message Go to previous message](/forum/theme/AudioRoundTable/images/up.png) ![Go to next message Go to next message](/forum/theme/AudioRoundTable/images/down.png) |
Mike.e
Messages: 471 Registered: May 2009
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Illuminati (1st Degree) |
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Oh also have you considered a version with 2 10" drivers such as CSX10" peerless,which have a decent displacement with shorting rings -cheap value for money drivers,and with 2 of them on one horn will result in low displacements.Cheers!
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Re: 12π and 15π horn loudspeakers [message #45748 is a reply to message #45739] |
Sat, 06 November 2004 13:42 ![Go to previous message Go to previous message](/forum/theme/AudioRoundTable/images/up.png) ![Go to next message Go to next message](/forum/theme/AudioRoundTable/images/down.png) |
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Wayne Parham
Messages: 18748 Registered: January 2001
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Illuminati (33rd Degree) |
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I've run into two issues, one of which represents another possible improvement to existing designs. Brad Litz mentioned that having the cooling vent in the throat might make noise, and that's a good point. But this represents an opportunity too. One of the things that plagues other large high-power basshorns is that the cooling vents are restricted. They are vented into relatively small rear chambers, and sometimes very near a wall so that flow is obstructed. So doing something to plumb those vents to outside air is probably a good idea.![](http://www.pispeakers.com/12Pi_external_cooling_vents.gif)
I'm thinking of doing something like shown above. I'll have the vent hole on the speakers fitted with a pipe fitting. It can be threaded, but I think a press fit is sufficient for no more pressure than we're talking about here. I'll also mount an exit fitting on the back of the cabinet and run a large rubber hose between them. Something like a heater hose, using the same diameter as the speaker vent. I'm thinking that this approach should really help keep the voice coils cool, and prevent unwanted noise at the same time. It's not a very difficult thing to do either, just a couple of fittings and a hose between them. The other thing I'm thinking of is how to mount the drivers. They can have access panels or the entire motor assembly can be removable, and fasted with a series of studs, somthing like mounting the head of a car to the block. I'd probably make the horn complete all the way to the throat and then have a matching cutout in the plenum. The drivers can be accessed through that cutout. That would allow the entire assembly to be made solid and without access panels, which would probably make for a better seal. The two surfaces that meet would employ a rubber gasket, and they would be pulled together tightly using a series of fasteners like head bolts.
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Re: 12π and 15π horn loudspeakers [message #45754 is a reply to message #45748] |
Sun, 07 November 2004 07:56 ![Go to previous message Go to previous message](/forum/theme/AudioRoundTable/images/up.png) ![Go to next message Go to next message](/forum/theme/AudioRoundTable/images/down.png) |
GrantMarshall
Messages: 77 Registered: May 2009
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Viscount |
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Hi Wayne.Regarding heat removal could you offer options depending on what the persons most common use for the speaker is? One thing I realize is that you don't have a "typical" user for some of your designs and what is "best" for one person isn't for the next. Adding some noise might be a tradeoff worth making if it provides much better cooling for some people. Having test numbers to compare options would help people make their choices. I like the idea of quick access panels over removable assemblies. Removable assemblies open up opportunities for vibration, poor fit if building isn't percise, and loosening up over time. Enjoy your Sunday. Grant.
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Re: 12π and 15π horn loudspeakers [message #45755 is a reply to message #45732] |
Sun, 07 November 2004 10:32 ![Go to previous message Go to previous message](/forum/theme/AudioRoundTable/images/up.png) ![Go to next message Go to next message](/forum/theme/AudioRoundTable/images/down.png) |
freddyi
Messages: 48 Registered: May 2009
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Baron |
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Hi Wayne (my apologies for not replying to note - am miserable) nice idea/simple to build & plenty of path - for home use driver requirements could be laxed - got any sims for 12" version w. couple diff TS? Best, Freddy
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Re: 12π and 15π horn loudspeakers [message #45758 is a reply to message #45757] |
Sun, 07 November 2004 16:31 ![Go to previous message Go to previous message](/forum/theme/AudioRoundTable/images/up.png) ![Go to next message Go to next message](/forum/theme/AudioRoundTable/images/down.png) |
GrantMarshall
Messages: 77 Registered: May 2009
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Viscount |
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I understand it's intended for high power users. I think a LOT of work has been done on heat reduction by speaker producers though and if a simple vent fixed the problem there wouldn't be the effort/cost to make things more durable. Drivers would never die from heat. It will be interesting to see if there is much of a difference with this system once you test it. Best wishes. Grant.
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Re: 12π and 15π horn loudspeakers [message #45759 is a reply to message #45758] |
Sun, 07 November 2004 18:47 ![Go to previous message Go to previous message](/forum/theme/AudioRoundTable/images/up.png) ![Go to next message Go to previous message](/forum/theme/AudioRoundTable/images/down.png) |
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Wayne Parham
Messages: 18748 Registered: January 2001
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Illuminati (33rd Degree) |
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You're right about the work on power handling. Just twenty-five years ago, the maximum power handling of drivers was about 200WRMS. Once they added a vent, those numbers doubled and even quadrupled. Some of the newer drivers are practically the same as an older model with a vent added.But the problem is that when a driver is mounted in a very small box, it starts to contain the heat. If the box is very small, it acts like the vent weren't there at all. So horns with small rear chambers are likely to suffer from heat related problems. In a horn with a small rear chamber, there is less heat exchange because the back chamber air gets hot and can't dissipate. I imagine it gets pretty hot in there at full power, and then the vent doesn't provide much cooling. Some have used metal chamber panels in an effort to conduct heat to the surrounding air, but it seems to me that a better solution might be to just vent to outside air in the first place. I guess the real test is to plumb the system for outside venting and see what happens to power handling. Then we'll know how much benefit it brings.
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