Print Page | Close Window

WinISD, Model Two Sets of Subs

Printed From: the12volt.com
Forum Name: Car Audio
Forum Discription: Car Stereos, Amplifiers, Crossovers, Processors, Speakers, Subwoofers, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=55988
Printed Date: March 29, 2024 at 12:39 AM


Topic: WinISD, Model Two Sets of Subs

Posted By: dwarren
Subject: WinISD, Model Two Sets of Subs
Date Posted: May 18, 2005 at 5:57 PM

I have been trying to model up two sets up subs on this program and I am having some issues with it.

So far I have entered the parameters of both drivers I am interested in; MTX 7500 12" svc 4 ohm and the Image Dynamic s IDMAX 12" dvc 2 ohm.

1. I am unable to view the upper parts of the graphs, i.e. the spl chart. It doesn't go past 103 db or so.

2. I am unable to enter the box volume manually. And is the box volume in cu ft or liters?

3. Why does the MTX have a lower EBP (43) and they recommend ported while the ID has a higher EBP (49) and they strongly suggest sealed.

4. Power input stays at 1 watt per foot or do I change that to my available power to 1 foot?

Thanks, hopefully something will get answered. It's long , sorry.

-edit- I think I have figured out the big difference, istead of looking at the max spl, I compared the two between the normal freqs. of about 35hz up to 80hz and the ID has the MTX beat by 10db's all the way through, does that sound about right? (both sealed enclosures whith optimum air sapce)

-------------



Replies:

Posted By: stevdart
Date Posted: May 18, 2005 at 7:11 PM

( Note:  the only version of WinISD I'm familiar with is THIS ONE, the newest version.  If you have an older version the following might not help...)

1.  You can adjust the chart by going to the pull-down toolbar, click File > Options > SPL.  Enter the start and stop numbers you want  to use for the range.

( Read the Help section "Using WinISD Pro" > "Graph 'Types Explained" )

2.  When you open a new project, and then select the driver you entered in the database, a small dialog box appears on the screen.  It has tabs "driver", "box", "vents", etc.  Open the "box" tab, double-click the number showing in the "volume" window to highlight it, and type in the volume you want.  You can use either cu. ft or liters, and you can always change any of the units of measurement by placing the cursor on top of it until it become a pointing finger, and clicking.

( Read the Help section "Using WinISD Pro" > "Designing your box" )

3.  Who recommends vented with an EBP of 43?

4.  In the dialog box I mentioned above, another tab is "Signal".  Open it, double click the 1 watt to highlight it and type in the Rms watts that will be going to the subwoofer(s).

( This is explained in the Help section under "Designing your box" )

dwarren, you should continually refer to the Help section for each new issue you are faced with...until you are completely familiar with how the program works.  No, I don't think there will be a 10 db difference if everything for both drivers is entered correctly.  That would mean that the efficiency of these two drivers is 10 db apart, which I'm sure is not the case.



-------------
Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.




Posted By: dwarren
Date Posted: May 18, 2005 at 9:27 PM

Well stevdart you never cease to amaze me. (I am laughing while typing this). Your answers are very similar to what my professors answer me with, "go look it up" type answers. I  do respect this because it teaches me learn and get what I need to know. Yhis answer is like the one I have posted in misc. for my thesis question. Are you a teacher now or previously?

Ok some answers to your questions, yes it is the most recent version that is free, I downloaded it the other day from that very site. I think, unfortunatley I am not at the same computer.

Next, MTX tech recommends using ported boxes for their woofers, and in fact they sell ported prefabs. They gave me specs for my box. I called them today and asked them why they would recommned these subs in ported boxes, and they didn't really answer the question.

So I will be giving those help sections a thorough look over. Thanks



-------------




Posted By: stevdart
Date Posted: May 18, 2005 at 9:50 PM

https://www.mtxaudio.com/caraudio/products/subwoofers/TechData_T7512-04.pdf

This looks like the PDF for the MTX sub you described.  Look at a couple of fishy-looking parameters:  the Fs is very high at 45 Hz.  The Vas is extremely low at 23 liters.  This is a set of parameters that would make me walk away quickly.  I don't know much about the MTX lineup, but I would guess that this Thunder 7500 series is a lower line sub marketed for beginners who just want some subz.  With an Fs of 45 Hz, it seems that SPL, not SQ, is the goal with these....but by the same token the meager Vas indicates that the field of sound from this sub is small.  Probably a good reason why they are emphasizing the vented box to get 3 more db's out of it.

Unless you've already made a purchase, consider looking at subs (whether MTX or another) in a higher line.  Do this quick comparison to these MTX subs:  https://www.mtxaudio.com/caraudio/products/subwoofers/TechData_T5512-04.pdf

Look at the difference in the Fs.  The 29 Hz on this one is more like something I would want to work with.  Here's a list of term definitions.

Edited to add:

I'm not a teacher but I play one on the internet...                         posted_image

......and did you write a good essay?



-------------
Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.




Posted By: dwarren
Date Posted: May 18, 2005 at 10:06 PM

hmmm, I do own these subs. They were a quick replacemnet for some older MTX subs I had.

I wish I could look at you have linked but the computer I am using doesn't have adobe so I will assume the obvious and take what you said. The definitions are great though I am happy to see that. Thanks for that.

What its boiled down to is that I want better sounding subs, I don't want this to turn into "what is the best sql sub" but I am considering the IDmax's because I can get them at cost (along with MTX gear). I want to have good dB levels in a sealed enclosure, but again at this point I am begining to lean towards the sq side of things (it's called maturing, it's amazingposted_image)

Thank you, internet professor.



-------------




Posted By: sedate
Date Posted: May 19, 2005 at 9:36 AM
Yo Stevdart:

2/3 of the way down on that definition link you gave I found:

SAF     Spouse Acceptance Factor

What? does that mean?
..I can't come up with an audio-related definition..

-------------
"I'm finished!" - Daniel Plainview





Print Page | Close Window