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Old 26th September 2006, 03:05 PM   #1
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Default For modelling open baffle: MathCad v Excel

Martin K or anyone

I want to be able different drivers in different baffle sizes, and needed EQ > effective efficiency.

FYI I would *really like to work out exactly how to use these, that I have:

MidBass
Hz say 90 - 480
Bl 17
Mms 70
Phase Plug Yes
cone Very stiff coated paper
Profile Curvilinear
faraday ring Yes
Le 0.2
VC mm 51
max power 300
1W Spl 98
Sd 855
Linear Xmax 3.3
Mech Xmax 10
Re 6.6


Midrange
Hz 480 *2500



Qts 0.4
Bl 8.9
Mms 7
cone paper
Profile Curvilinear
faraday ring Yes
Le 0.5
VC mm 38
max power 160
1W Spl 100
Sd 150
Linear Xmax 1
Re 5.3


If you are good with Excel, how long might it take to learn MathCad, and is there a license fee?

Thanks
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Old 26th September 2006, 03:51 PM   #2
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Martin charges a nominal fee for his MathCad worksheets, but they are dead-easy to use -all you do is enter the parameters, and adjust to get the desired response. They are also staggeringly powerful, and by a long way the best software available to the DIY builder. LSPCad is great if you're feeling rich (or so I gather), but I know I certainly can't afford it, nor does it offer the background on many different types of enclosures like TLs, open baffles and horns that Martin does. I cannot recommend them highly enough -in fact, I'd call them an essential tool for any DIY speaker builder.
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Old 26th September 2006, 04:38 PM   #3
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Open baffle and modelling. You guys are trying to ruin the fun of OB experimenting. If it doesn't include room dimensions and speaker placement in the model, then why even bother? Once you take the drivers out of a box, then the room becomes an integral part of the speaker, especially in the bass frequencies.
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Old 26th September 2006, 05:17 PM   #4
MJK is offline MJK  United States
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MathCad vs. The Edge

The Edge models drivers on a wide variety of baffle shapes and predicts the influence of the baffle on the SPL response. It does both open and closed box baffles. It does not include T/S modeling of the driver so the drivers fs and 12 dB/octave roll-off will not be included in the plots. The interface is very good and the run times are extremely quick (I am envious). It is a great tool and I use it often to sanity check my own results.

MathCad is not as slick an interface but all you really need to do is enter numbers and let it calculate. It runs longer than the Edge and will not do anything other than rectangular baffles at this time. But it does include the driver's T/S low frequency performance and some ideal crossover behavior (think active crossovers) between multiple drives on the same baffle. The MathCad OB worksheets also include reflections from the room's floor and rear wall. If one assumes that the sound radiating to the side is minimal, then these reflections can be though of as the early reflections from the room. This is an incremental step beyond a free space solution, but I think it is in the right direction.
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Old 26th September 2006, 05:55 PM   #5
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Martin since you've got floor and rear wall reflections covered, my days of just winging it are numbered. I've already ordered the stuff I need to start doing measurements necessary to go active and multi-way. Now I need to upgrade to your latest program from the old free version that I've been using.
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Old 26th September 2006, 06:26 PM   #6
MJK is offline MJK  United States
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Ohhh, I think there is still plenty left to wing.
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Old 27th September 2006, 03:01 PM   #7
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Hi Martin

It factors in driver Vd, Qt etc. . baffle size . .

On the one graph, can it plot the response of a driver, open baffle v vented?
and horns too, specifying M factor?

System requirements?

Sounds great, how much is it?

Thanks

Richard
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Old 27th September 2006, 03:52 PM   #8
MJK is offline MJK  United States
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Quote:
On the one graph, can it plot the response of a driver, open baffle v vented?
and horns too, specifying M factor?
There are separate models that do each of these enclosures, you can put them on the same plot by copying and pasting to form a graphic overlay. I have seen this done but never done it myself.

All the information you need to test your PC system and see what the software looks like and how they perform are on my site. Follow the link to the advanced MathCad models page.
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Old 28th September 2006, 03:24 PM   #9
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Default MathCad v 13

Anyone know how stable (lack of bugs) MathCad is in version 13?

Or where to check this?

Thanks
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Old 28th September 2006, 03:50 PM   #10
MJK is offline MJK  United States
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I have MathCad 13 and it is reasonably stable, much better then 12. It has occasionally crashed on me, which 2000 and 11 almost never did, but not very often.
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