Win ISD help please.

**cradeldorf** · January 29th, 2011, 05:38 PM

Hi Guys, I finally got around to trying out the win ISD program and attempted to model the design I posted a while back. I guess one of the questions I have is what am I trying to achieve? What does a good plot curve look like compared to a bad one? I'm posting 2 pictures of the plot, one showing the port and one showing the box volume. Also if you have any idea on what the end correction thing means on the port window I'd be interested in knowing what that is too. I added the cabinet design so you know what I was talking about.
Thanks.

**gvasale** · January 29th, 2011, 06:37 PM

If I'm seeing what you see, there is really no difference. Scale at 20hz and at 50hz and also at 200hz are virtually identical. I don't know what this software is, but if is a curve to see what has been gained by porting the enclosure, there has been no change. Or the test method isnt set up correctly. Just my guess.

**cradeldorf** · January 30th, 2011, 01:18 AM

Originally Posted by gvasale

If I'm seeing what you see, there is really no difference. Scale at 20hz and at 50hz and also at 200hz are virtually identical. I don't know what this software is, but if is a curve to see what has been gained by porting the enclosure, there has been no change. Or the test method isnt set up correctly. Just my guess.

It's a program where you put in your drivers parameters and your box parameters and your port size and the program plots out the performance of the three as a unit....I think. What your seeing is the same one I just switched windows so you could see the parameters of the box volume and the port settings. my question is what is an optimum looking curve and what is the significance of the -3db range? What would an optimum curve look like? or am I not trying to shoot for an optimum curve?

**Earl K** · January 30th, 2011, 09:54 AM

Good to see you are starting to take a more measured approach to this ( rather than just building boxes & hoping for the best ) .

Ultimately ( after playing with all the permutations & combinations / ie; alignments or tunings ), you're going to find that all 604 variants, generate the most extended bass response when used in a large enclosure ( ie; in a Bass Reflex box that means up to about 9.5 cu ft and typically no smaller than 7 cu ft ).

- Yes, you are looking for a "good" curve that extends well down into the LF areas .
- Your curve can be considered "bad" , if you are expecting reasonable bass response .
- OTOH, your curve can be considered "good" / if there's a "helper" woofer handling the bass duties .

I consider the following curve "good" / especially considering the size of box / as well as after factoring in a bit of LF room gain ;

cheers

**604man** · January 30th, 2011, 09:59 AM

Why don't you use the on line CAD here Loudspeaker enclosure calculating with Thiele Small parameter
It's hard to see the graphs on your post, What speaker are you using? what is Vb?
....GC

**westend9** · January 30th, 2011, 10:06 AM

Earl pretty much nailed it. Did you know that you can drag the curve (a point on the curve, actually) to have a better alignment? So.....if you want the rolloff of the bass to be steeper, you can choose the -3db point and drag that to the left side of the screen.

Two tips: Make sure you have the exact T/S parameters of your driver entered into the program, don't rely on the Winisd params. Try increasing or decreasing box sizes and alignment numbers to get a port that will will be friendly with your drivers and allow for the best rolloff characteristics. The 172" port length is not going to work.

Good luck with your enclosures.

**cradeldorf** · January 30th, 2011, 10:38 AM

So what Earl is saying is if I want good Bass response I want the curve to cross the -6db line at as low a frequency as it can? Right?... That is if I want the house to jump off of it's foundation...which I do. : )

**cradeldorf** · January 30th, 2011, 10:46 AM

Originally Posted by westend9

Earl pretty much nailed it. Did you know that you can drag the curve (a point on the curve, actually) to have a better alignment? So.....if you want the rolloff of the bass to be steeper, you can choose the -3db point and drag that to the left side of the screen.

Two tips: Make sure you have the exact T/S parameters of your driver entered into the program, don't rely on the Winisd params. Try increasing or decreasing box sizes and alignment numbers to get a port that will will be friendly with your drivers and allow for the best rolloff characteristics. The 172" port length is not going to work.

Good luck with your enclosures.

Thanks Westend, They didn't have the 604 in the list so I had to put it in manually. I used the T/S parameters from the altec literature and filled in as many as I had. The only one that might be iffy is when I described the speaker magnet size I guesstimated it at 6 inches in dia and 7 inches long. I had read about the dragging of the curve but hadn't tried it, makes good sense though.

**voice of the theater** · January 30th, 2011, 11:27 AM

I think it's great that you're going to build some new cabinets for your 604's--you'll need to build larger cabinets than the black ones you're currently using to get the most out of those drivers. From your previous posts I recall that cabinet size was a concern due to the amount of space there is in your listening room--sounded to me like you wouldn't be comfortable with cabinets that are larger than the Heathkit cabs you own (that are currently gathering dust?). I would recommend that you modify your Heathkit cabinets and compare their sound to the new cabs that you build--you might be surprised that the Heathkits sound better than the ones that are currently on the "drawing board" and it wouldn't be much work to "fix" those Heathkit cabs. You might even want to consider modifying the Heathkit cabinets first--and you may decide you don't need to build a new pair. From your previous posts it sounds like the tuning of your Heathkit cabinets is WAY off. If they were mine, I'd first remove the "shelves" that someone added--that would get them closer to their "stock" configuration. Then, I'd reduce the port size (most likely by quite a bit) either by using your computer program to determine the optimum port size and/or fine tuning by ear (or even designing an adjustable port). I think those Heathkit cabs, with the right port size and no "shelves" would sound amazing......

**cradeldorf** · January 30th, 2011, 11:37 AM

Thanks Vott....and yes they are collecting dust....in the kitchen.

You wouldn't believe me...well you probably would but this morning I thought there was something wrong with one of the speakers so I tried adjusting the balance and realized that it was way over to one side....I'm not sure when that happened but I'm betting it was way back when I switched to the big square ports. I remember switching it back and forth between a big square port and the original round hole I had put in them. needless to say i think all this time it was off. I also noticed that ever since I switched the ports it didn't do any soundstaging like they used to...I think it was because I had the balance way off. I can be rather retarded at times....well most of the time. Now I'm gonna have to do more listening to see what I really have.....they do sound a lot better now though.