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Multi-Way Conventional loudspeakers with crossovers

New user. First speaker build. All the usual questions!!
New user. First speaker build. All the usual questions!!
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Old 15th February 2020, 01:39 AM   #11
Galu is offline Galu  Scotland
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Was just trying to keep it simple Dave!

A Qts of 0.87 is best suited to open baffle mounting, but I didn't want to go there.
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Old 15th February 2020, 01:41 AM   #12
jjams82 is offline jjams82  United Kingdom
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Yeah, goofy specs from goofy drivers eh. The inter door panel of a car, if properly sealed, would probably be about right. It certainly was close in my MX5. Their 2 part with external crossover will freak me out sometimes shaking my trousers about in the current car. They can't pump out huge power without breaking up at the low end though.

Anyways.. It seems that anything about 16-17 litres or above breaks into the -3db 60's.

15.38 litres gets 69.04hz -3db, so they don't have to be huge to meet up with a sub of some sort. I'll likely go a bit bigger and lower into the 60's but it's good to know it'll be a simple job and I can whack it together fairly straightforward without obsessing over wether it's 22.5 litres or 22.6 litres. It's all good enough.

I had I can live with that for an almost zero cost weekend project. If it works out, mid 60's ain't a bad spot to meet up with a sub.

@planet10, - I have no idea what the F6/F10 are, this calculator doesn't show it, but i suspect it rolls of fairly steep after the 60hz ish zone.

Final couple questions for anyone who has an opinion:

--Any thoughts on damping material? I have some old fluff that'd do the job nicely enough for free.

--Aside from sturdy bracing, is there anything worth doing inside the box, or should I just stick it together simple at right angles with simple bracing?

Quote:
Originally Posted by Galu
Was just trying to keep it simple Dave!

A Qts of 0.87 is best suited to open baffle mounting, but I didn't want to go there.
Yes... Simple is what I need for this first mess-about with drivers I have laying about idle! I don't want to get into the world of open baffle funny-business, I'm happy if they just sound half decent in their deliverable frequency range[/quote]

In fact, as a first-timer a sort of ok-ish result with room for improvement is about the perfect way to get me wondering how they might be improved upon in v2.0... And so it goes.
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Old 15th February 2020, 01:46 AM   #13
nigelwright7557 is online now nigelwright7557  United Kingdom
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I would go for sealed too.
You can get over extension with ported boxes.
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Old 15th February 2020, 03:26 AM   #14
planet10 is offline planet10  Canada
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Quote:
Originally Posted by Galu View Post
Was just trying to keep it simple Dave!
But a useless piece of info (except for use in a filter) is not very simple.

dave
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Old 15th February 2020, 03:31 AM   #15
planet10 is offline planet10  Canada
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Originally Posted by jjams82 View Post
@planet10, - I have no idea what the F6/F10 are, this calculator doesn't show it,
If your modeler does not give you a graph to read, throw it out. The shape is as important as the numbers.

A woofer with that high a Q can be put into as large a sealed box as you can live with, and if it is still underdamped, you can make it aperiodic to push the Q lower..

dave
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Old 15th February 2020, 12:02 PM   #16
Galu is offline Galu  Scotland
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Quote:
Originally Posted by planet10 View Post
But a useless piece of info (except for use in a filter) is not very simple.
By 'trying to keep it simple', I was referring to my admittedly way too simple description of a system Q of 1.0. I do know what that really looks looks like on a graph of dB against frequency.

Ideally, I would have recommended designing for a system Q of 0.7, but the simple calculator to which I referred did not provide a sealed cabinet solution when inputting a Qts of 0.87.

As to the inappropriateness of using f3 to describe the bass extension, I stand ready to be educated. I do see bass extension nowadays being quoted thus: '41Hz (-6dB re. 200Hz)'.
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Old 15th February 2020, 12:17 PM   #17
Galu is offline Galu  Scotland
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Quote:
Originally Posted by jjams82 View Post
--Any thoughts on damping material? I have some old fluff that'd do the job nicely enough for free.

--Aside from sturdy bracing, is there anything worth doing inside the box, or should I just stick it together simple at right angles with simple bracing?
Fill the enclosure loosely with BAF wadding and adjust the amount by ear (the contents of an old pillow would suffice).

A small box is rigid and may not require bracing. A larger box would benefit from an open bracing shelf placed horizontally across the middle of the box.

Again, that's keeping it simple.
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Old 15th February 2020, 12:25 PM   #18
jjams82 is offline jjams82  United Kingdom
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Quote:
Originally Posted by planet10 View Post
If your modeler does not give you a graph to read, throw it out. The shape is as important as the numbers.

A woofer with that high a Q can be put into as large a sealed box as you can live with, and if it is still underdamped, you can make it aperiodic to push the Q lower..

dave
I'd also been playing with another, results below in the pics.

Aperiodic is a term I'm not familiar with and with my lack of knowledge google isn't much help - can you give me the right terms to search or a link that explains it to an idiot?

Quote:
Originally Posted by Galu View Post
Fill the enclosure loosely with BAF wadding and adjust the amount by ear (the contents of an old pillow would suffice).

A small box is rigid and may not require bracing. A larger box would benefit from an open bracing shelf placed horizontally across the middle of the box.

Again, that's keeping it simple.
Excellent simple advice. I will do just that. Many thanks.

Now... Do I get around to slapping this up today?? Hmmm... day off work lazing in bed, or day making cool stuff based on the internet's usefullness... We shall see
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Old 15th February 2020, 12:33 PM   #19
jjams82 is offline jjams82  United Kingdom
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Originally Posted by jjams82 View Post
I'd also been playing with another, results below in the pics.
Ooops, forgot the pics. Here they are. Not the best curve, but it'll do for a first try right?
Attached Images
File Type: png Screen Shot 2020-02-15 at 12.16.17.png (67.1 KB, 54 views)
File Type: png Screen Shot 2020-02-15 at 12.16.39.png (66.3 KB, 55 views)
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Old 15th February 2020, 01:49 PM   #20
AllenB is offline AllenB  Australia
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New user. First speaker build. All the usual questions!!
Those curves look ok.
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