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Multi-Way Conventional loudspeakers with crossovers

Loudspeaker volume
Loudspeaker volume
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Old 12th March 2018, 05:11 PM   #11
nomis514 is offline nomis514  Canada
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So I guess the question is :

I know Hoff. iron law is saying that: efficiency = F3 x volume^3 but does that apply only while considering the same driver?

Let's say I am able to find a driver that is more efficient by 3db than the one I have on paper and with a smaller F3, would it be more sensitive in the same enclosure?
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Old 12th March 2018, 05:37 PM   #12
scottjoplin is offline scottjoplin  Wales
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Probably, impossible to say without the parameters, find the specs of some suitable drivers and have a play with this, it will give you a good idea of what to expect mh-audio.nl - Home
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Old 12th March 2018, 06:14 PM   #13
Scottmoose is offline Scottmoose  United Kingdom
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Originally Posted by Presidentovich View Post
Sorry for my question but what loudspeakers are this???
I think it is a waste of resource, why want we to build large loudspeaker with poor WAF and use maybe only half the speaker volume???
A large number of commercial floorstanders have internally partitioned off cavities -these can often be filled with dried sand, lead-shot or similar. While in some ways it might seem inefficient engineering, it can actually be quite practical. Some (many) prefer the appearance of an integrated enclosure to a physically smaller box sitting on a pair of stands. And since most loudspeaker stands aren't likely to win any awards as pieces of objet d'art, it's understandable. In the same way, it's not necessarily wasting resources -depending on implementation it can actually use fewer than a pair of standmounts with a pair of stands when you account for materials, finishing, packaging, shipping etc.
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Last edited by Scottmoose; 12th March 2018 at 06:27 PM.
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Old 12th March 2018, 06:44 PM   #14
nomis514 is offline nomis514  Canada
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Originally Posted by scottjoplin View Post
Probably, impossible to say without the parameters, find the specs of some suitable drivers and have a play with this, it will give you a good idea of what to expect mh-audio.nl - Home
Can I use this calculator even if my loudspeaker is open/ported?
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Old 12th March 2018, 06:53 PM   #15
planet10 is offline planet10  Canada
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Loudspeaker volume
Every driver has its own range of volumes that it is happy to live in. This dictates how big the speaker can be. If it is not large enuff to reach the floor the sides can be extended down to the floor creating an empty cavity — this should be fileld with something (sand, kitty litter…).

Also note that a tower speaker is often an ML-TL. It may look on the surface to be a reflex enclosure but it has different behaviour and has to be treated differently.

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Old 12th March 2018, 07:12 PM   #16
scottjoplin is offline scottjoplin  Wales
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Originally Posted by nomis514 View Post
Can I use this calculator even if my loudspeaker is open/ported?
If you click on "calculators" at the top, a list comes up with different loudspeaker calculators on the left, I don't know how accurate they are, not very I wouldn't imagine, but it will give you an idea
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Old 12th March 2018, 08:12 PM   #17
chrisb is offline chrisb
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Originally Posted by nomis514 View Post
Thanks a lot for your replies.

I did not know about the Hoffman's Iron law. Makes a lot of sense.

I am now thinking what can be done for my current bookshelve. Obviously, I won't be able to touch the enclosure volume. I am wondering if I can replace the woofer by one producing lower bass. I guess I'll have to compromise on the sensitivity. I curently have a VifaPL11WH09. The guy is suggesting this one.

What do you guys think?

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I'd stick with the Vifas - you have them on hand, and in an appropriately designed enclosure, they should yield quite acceptable performance. Unless you're keen to make using any of a number of modeling programs part of your learning curve, I wouldn't be surprised if designs in any of the popular flavors haven't already had all the math done. Of course I'm famously lazy in that regard, but I'd imagine that a speaker design program that doesn't allow for different types of alignment / loading is probably worth passing by?



Personally, I always prefer a floor-stander for the reasons already listed above, and unless complicated internally, don't find them any harder to build than a bookshelf - the difference in material costs to do so is generally far less than a "decent sounding" pair of stands.
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Old 12th March 2018, 10:41 PM   #18
Ron E is offline Ron E  United States
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Quote:
Originally Posted by nomis514 View Post
I know Hoff. iron law is saying that: efficiency = F3 x volume^3 but does that apply only while considering the same driver?
An iron law applies to all drivers.

Quote:
Originally Posted by nomis514 View Post
Let's say I am able to find a driver that is more efficient by 3db than the one I have on paper and with a smaller F3, would it be more sensitive in the same enclosure?
See above. You need to start asking less general questions you have a chance at understanding the answers to.

So you have a PL woofer, how big of a box? what is the tuning frequency? what is the crossover? what is the tweeter? Why do you want to change the woofer? Why not just get a subwoofer?

The Scanspeak woofer is lower sensitivity and it has a sizeable peak at the top end that will have to be dealt with.
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Old 13th March 2018, 12:21 AM   #19
Ron E is offline Ron E  United States
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Here is a visualization of hoffman's iron law:
Vb vs F3 plotted for 4 different sensitivities: 84, 87, 90, 93 dB

Note that you can gain 3dB in sensitivity by increasing box size by 2, or by increasing F3 by 1.26 times. In order to have a lower F3 and a larger sensitivity, you must have a larger box.

This is what is meant by low F3, small box, high sensitivity, pick 2.

If you want high sensitivity and low F3, you need a big box
If you want a small box and a low F3, you need low sensitivity
If you want high sensitivity and a small box, you need a high F3.
Attached Images
File Type: png hoffmans iron law.PNG (43.1 KB, 49 views)
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Old 13th March 2018, 09:35 PM   #20
nomis514 is offline nomis514  Canada
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Quote:
Originally Posted by Ron E View Post
Here is a visualization of hoffman's iron law:
Vb vs F3 plotted for 4 different sensitivities: 84, 87, 90, 93 dB

Note that you can gain 3dB in sensitivity by increasing box size by 2, or by increasing F3 by 1.26 times. In order to have a lower F3 and a larger sensitivity, you must have a larger box.

This is what is meant by low F3, small box, high sensitivity, pick 2.

If you want high sensitivity and low F3, you need a big box
If you want a small box and a low F3, you need low sensitivity
If you want high sensitivity and a small box, you need a high F3.
Ok let's say I want : "A small box and a low F3, you need low sensitivity" How can I achieved this? I guess have to replace the woofer right? That's why I asked earlier if it would be possible to find a woofer of "better quality" to cope for the lost in sensitivity and get bass extension at the same time.

Last edited by nomis514; 13th March 2018 at 09:42 PM.
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