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Drivers and their enclosures

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odc04r View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote odc04r Quote  Post ReplyReply Direct Link To This Post Posted: 18 January 2017 at 11:04am
Well the same principles apply, HiFi guys tend to be less about maximum SPL and more into other exotic details of designing enclosures but the fundamentals are the same.

T/S parameters are very useful for modelling a system at small signal levels, where driver and magnetic gap behavior remains linear. They are also most useful for under ~400Hz modelling although can be extended higher if you are more careful. Under there you can generally assume the wavelength of sound is much larger than your cabinet dimensions and so doesn't interact with it much in terms of resonance.

They will not predict large signal effects so well necessarily, and they can't really tell you anything about the particular way some drivers sound compared to each others. There is also a statistical distribution of parameters over drivers due to manufacturing tolerances and that parts of them will loosen up slowly over time as they are used.

So in summary, they are massively better then nothing at all and allow you to get within 90% of your design goals I'd say. But at some point you need to build a prototype, account for real world effects + adjust, then perhaps build a better mk2 model with what you have learned.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote George1234 Quote  Post ReplyReply Direct Link To This Post Posted: 18 January 2017 at 12:37pm
In terms of parameters, surely the designs for a full scale rig can be scaled down to suit any size of driver?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote DMorison Quote  Post ReplyReply Direct Link To This Post Posted: 18 January 2017 at 12:50pm
Originally posted by George1234 George1234 wrote:

In terms of parameters, surely the designs for a full scale rig can be scaled down to suit any size of driver?
 
Not in all cases, no.
 
Some of the ways in which cabinet design features affect the sound are based on the wavelength of the sounds you want to reproduce, as well as the drivers used - horns in particular are very dependant on wavelength related principles.
So if you want a horn to go down to 40Hz, it has to have a minimum path length and mouth area, regardless of whether you put a 5" hifi driver at the start of it or a 21" PA sub.
 
(There are slight exceptions based on sub-types of horns etc (eg tapped horns are less dependant on mouth area) and acoustic environment, but you don't want to start learning to design by relying on exceptions, you're better to learn the fundamentals first.)
 
HTH,
David.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote George1234 Quote  Post ReplyReply Direct Link To This Post Posted: 18 January 2017 at 1:01pm
Ah okay, Im very interested in all of this - having only started looking to what actually goes into a speaker, I dont know what these fundamentals are, can you help? 
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odc04r View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote odc04r Quote  Post ReplyReply Direct Link To This Post Posted: 18 January 2017 at 6:17pm
If you really want to learn fundamentals your best bet is to buy some second hand textbooks and read 'em! The internet is a great resource but sometimes nothing beats an actual book. If you are good enough at maths to understand complex numbers then get 'The fundamentals of acoustics' by Berenak. Otherwise look for something a little less technical.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote fat_brstd Quote  Post ReplyReply Direct Link To This Post Posted: 18 January 2017 at 11:29pm
Originally posted by odc04r odc04r wrote:

If you really want to learn fundamentals your best bet is to buy some second hand textbooks and read 'em! The internet is a great resource but sometimes nothing beats an actual book. If you are good enough at maths to understand complex numbers then get 'The fundamentals of acoustics' by Berenak. Otherwise look for something a little less technical.


This one? - https://en.wikibooks.org/wiki/Acoustics/Fundamentals_of_Acoustics
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Post Options Post Options   Thanks (0) Thanks(0)   Quote DMorison Quote  Post ReplyReply Direct Link To This Post Posted: 19 January 2017 at 12:44pm
Originally posted by George1234 George1234 wrote:

Ah okay, Im very interested in all of this - having only started looking to what actually goes into a speaker, I dont know what these fundamentals are, can you help? 
 

As odc04r says, Beranek is a benchmark for those with the math skills to follow it, unfortunately that does not include Me.

 

This is much more basic, and a little dated, but very easy to digest: https://www.amazon.co.uk/Introduction-Loudspeakers-Enclosure-Design-BP/dp/0859342018

 

Vance Dickason's "Loudspeaker Design Cookbook" (on about its 73rd edition by now I think) would be a little more intermediate, but doesn't cover Horns.

 

For more specific stuff about horns design, you might try some of the articles here: http://www.quarter-wave.com/Horns/Horn_Theory.html or this one: https://www.grc.com/acoustics/an-introduction-to-horn-theory.pdf

 

HTH,

David.

 

Edit - correct attribution / spelling



Edited by DMorison - 19 January 2017 at 12:52pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote DMorison Quote  Post ReplyReply Direct Link To This Post Posted: 19 January 2017 at 12:47pm
Originally posted by fat_brstd fat_brstd wrote:

Originally posted by odc04r odc04r wrote:

If you really want to learn fundamentals your best bet is to buy some second hand textbooks and read 'em! The internet is a great resource but sometimes nothing beats an actual book. If you are good enough at maths to understand complex numbers then get 'The fundamentals of acoustics' by Berenak. Otherwise look for something a little less technical.
 

 

Edit: un-buggered quotes


Edited by DMorison - 20 January 2017 at 2:00pm
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odc04r View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote odc04r Quote  Post ReplyReply Direct Link To This Post Posted: 19 January 2017 at 1:14pm
Yeah, that's the badboy. Good shout on the loudspeaker cookbook too, that's a little more digestible without spending hours.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote George1234 Quote  Post ReplyReply Direct Link To This Post Posted: 19 January 2017 at 1:32pm
Safe!

Cheers for the help - I'll keep everything posted, and ask for help accordingly!

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