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Old 31st March 2007, 05:26 PM   #481
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Enjoy. Well worth the outlay.

Re the different mouths, there's beauty in simplicity but it can be taken too far. The existing profile was quite carefully shaped. Bruce & Loreena's expansion for example has a parabolic section which smooths the response slightly. Your ideas are interesting though -you might want to try one out. Just be careful to get the flares right & ensure the correct degree of end correction, which they're currently somewhat out on.
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Old 6th April 2007, 08:49 AM   #482
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Is there any performance difference between having the stepped horn mouth and doing the alternate? My gut tells me no, but then why would you have put that on the plans
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Old 6th April 2007, 09:53 AM   #483
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Quote:
Originally posted by Glowbug
Is there any performance difference between having the stepped horn mouth and doing the alternate? My gut tells me no, but then why would you have put that on the plans
The only affect the alternate should have is to save wood at the expense of having to make some cuts that aren't 90 degrees.

There is also the cosmetic consideration.

When we build Aiko we are going to do the 45s...

Click the image to open in full size.

BTW: let me introduce the newest (& smallest Spawn family member -- daugher of Mikasa. For the Lyeco LY401F (this desigb qon Scott a pair over on the Full Range Forum) althou FE108eS should drop right in.

dave
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Old 8th April 2007, 06:54 PM   #484
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Hi,

I am considering building myself some full-range speakers to replace my current 3-ways. I like the look of the tall double horns. I am a little confused about the way to choose drivers though. I understand from the "single driver website", http://www.melhuish.org/audio/horndriver.html, that the criteria for apropriate horn drivers is a low Qts (0.2 to 0.3), really low xMax, and a strong magnet (high Bl?). Fostex sigmas seem pretty good for this. I have noticed though that some of the drivers people are using in these horns dont have the properties I just described and are getting good results. How much do the measurements matter and what will give the best results with the BVR style horns?

Thanks for the help,
Mark
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Old 8th April 2007, 07:34 PM   #485
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Hi Mark

Would that there were a simple answer. Frankly, within reason, you can use anything if you design the cabinet to suit it. Dave & I have done a BVR for the Visaton B200 for example (Oscar: v. similar to Loreena), which has a 0.7Qt and high 102 litre Vas).

Of course, the BVRs aren't like 'normal' horns (whatever that means) -in reality, like PA scoop-bins, they're reflex cabinets with, er, slightly larger than average vents. Of course, the presentation is rather different to the average BR box -they couple to a large quantity of air, just like other horns do, so their presentaion is very similar, although they can't go as loud without distorting. OTOH, many longer path designs have inherently higher ripple as they too are compromises (i.e. not 'real' horns, but hybrid QWRs / horns) and cranking them loud won't erradicate that, so in some cases you could arguably end up in a much of a muchness situation

As a rule, a nice mid-Q unit with moderate Vas is good for BVR loads, just as it would be for their more common, small vent-cousins, primarily because they're easy to work with, and you can keep the cabinet size reasonable.

For long path horns, a low Q is useful (although not mandatory) as you've got a powerful motor there, and ergo, potentially superior dynamics.

Hope some of that helps
Scott
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Old 8th April 2007, 07:37 PM   #486
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Quote:
Originally posted by markgoespop
How much do the measurements matter and what will give the best results with the BVR style horns?
BVR stands for Big Vent Reflex (or as my buddy says BAVR), so they really need to be looked at as bass reflex when choosing a driver. This is why Fosex FExx7, Lyeco LY801 & Visaton B200 can work in these (and often better than the FExx6 brethern). You will note in the Harvey sims how the cabinet almost completely dominates the horn's performance -- we figure these should be pretty versatile.

Scott is better prepared to say how the Qts/Vas affects things.

dave
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Old 8th April 2007, 08:02 PM   #487
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It's an interesting issue. Higher Q can actually allow a smoother response on occasion. Martin noted in one of his BLH papers that the resistive impedence of the horn can be quite effective at damping the high Q unit's ringing response. Of course, that's very much dependant on the design. But the trade-off is a reduction in dynamics, as Ron has described elsewhere.

FWIW, one of the things I've found working with pipe horns is that you can play off Q against Vas. Normally, high Vas demands a large box, but if the motor strength is sufficiently low, you can get away with a smaller Vb than you might expect. The opposite applies -high Q will work, if Vas is low. Low Vas, low Q is OK too. The nightmare is high Vas, high Q, which demands a downright monster of an enclosure. As a quick ROT, the same thing applies to hybrid QWR / horns, though I'm sure there are exceptions.

The BVRs OTOH, are relatively forgiving, as seen by the B200 cabinet we've done. More so than small vent reflex cabinets actually. If you can get sufficient Vb, the large vents appear to act as Martin describes above, and damp out the response. Generally mid Q, mid Vas make for an easier / more compact life and design though, just as they would for a smaller vent reflex cabinet.

BTW -Dave, did my emails get through OK this time? I'm going to try to shift over to the Frugal-horn address either this evening or tomorrow, if I can persuade my PC to play ball for once it its life... At the moment, hotmail appears to be down yet again, which is pretty much the last straw, and makes me wonder just how many of my emails over the past couple of days to different people have actually got through.
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Old 8th April 2007, 08:49 PM   #488
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Quote:
Originally posted by Scottmoose
BTW -Dave, did my emails get through OK this time?
I got a Volt one, and an OB one... busy cleaning up the house, etc for Easter dinner... oops gotta go light up the oven...

dave
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Old 8th April 2007, 09:02 PM   #489
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A-ha. One might be lost in the machine somewhere. Not too critical though luckily.

Cooking -I know that feeling... my skills are a trifle limited, but I can do some good cakes, which has its uses at Christmas & Easter etc. Enjoy the meal Dave!
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Old 8th April 2007, 09:54 PM   #490
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Quote:
Originally posted by Scottmoose
Enjoy the meal Dave!
Same from here Dave! And as to emails...either they are being sent through leaky pipes or, for Harry Potter fans, the owls can't navigate. Plus (Scott knows this) my owl doesn't carry heavy loads. Some union regulation I presume.



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