question about WINISD.. about ohm values

[vehementSPL 10+ year member]

You know I have always used WINISD and I feel ashamed to ask this honestly. But I wonder if I have been wrong on this the whole time. When you are entering the watts for the graph it ask for series resistance.. But on all the graphs I have always done I put the resist of what I was going to have the speaker wired at whether or not it was series or not. Should I always put the series resistance of the sub no matter what is the final load of the amp. does apply with multiple subs as well.... The reason I ask is because when you change that number it GREATLY changes the graph. (now I know in car response will be different)But just curious which input I should be putting it because I am designing a box for my wall now and This actually changes the design I wanna do a good bit . So somebody chime in please that knows a good amount about car audio . thanks for the help

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[helotaxi 5,000+ posts]

Series resistance in the signal portion of the WinISD tabs is for the series resistance of the wire inline with the speaker. It has zero to do with the speaker itself. 0.1 or whatever the default value is, is usually where you should leave it unless you are actually wiring in a resistor.

 

[vehementSPL 10+ year member]

really crap I didn't know that. I still have been doing it wrong. ok WHAT is series resistance of a wire?

 

[ngsm13 5,000+ posts]

I only use winisd to double check port length... everything else is merely inaccurate...

nG

 

[helotaxi 5,000+ posts]

Actually it's very accurate for theory. Nothing is going to model real world in car response without a lot of work. For home enclosures it's fairly close.

 

[vehementSPL 10+ year member]

Actually it's very accurate for theory. Nothing is going to model real world in car response without a lot of work. For home enclosures it's fairly close.

Yeah and for walls pretty accurate ( maybe not max spl) but musical response pretty close since the speakers are right behind you

 

[vehementSPL 10+ year member]

Oh yeah. One more question. When comparing spl between two subs in winISD(i know vehicle matters) is it accurate to tell which sub is louder or is that just crap. It seems that it couldn't . just curious if anybody has done any real world test between two subs that was both graphed on winisd and if it was correct between the differences

 

[helotaxi 5,000+ posts]

Not at all accurate for walls, actually. You shouldn't be comparing anything out of WinISD really other than basic response, and even when doing that you need to understand what the car is going to add to the equation or at least have a good idea. Without knowing what the cabin gain curve looks like, it's impossible to determine which setup is going to be louder using WinISD, unless the SPL tab curves are not even close. If the difference is that glaring though, you shouldn't need a computer program to tell you because something is going to be hugely different between the tw setups.

 

[Immacomputer 10+ year member]

I'm pretty sure that Winisd just takes your sensitivity value and uses that for its SPL graphs. I wouldn't trust it at all. Try modeling some 6.5" speaker sealed with low excursion and compare it sealed with some 18" sub with a good amount of throw. Plot the same power and see which one says will get louder. If I remember correctly, it will say which ever has the highest sensitivity will get louder. That's just not true in many cases.

The theoretical responses aren't too bad to use to get an idea of how things will sound but trying to model them with specific transfer functions would just be too difficult.

 

[vehementSPL 10+ year member]

Not at all accurate for walls, actually. You shouldn't be comparing anything out of WinISD really other than basic response, and even when doing that you need to understand what the car is going to add to the equation or at least have a good idea. Without knowing what the cabin gain curve looks like, it's impossible to determine which setup is going to be louder using WinISD, unless the SPL tab curves are not even close. If the difference is that glaring though, you shouldn't need a computer program to tell you because something is going to be hugely different between the tw setups.

Yeah I understand that. But as far as response go just me personally all the walls I have done response wise graphed pretty close to the T on what WIN ISD said it would be. no trunks hell no! Now with windows up on the meter no but for daily musical windows down yes. And I was asking box comparing to box. if one says it is louder will that box be louder in person. It doesn't seem that it could know that BUT I will say most of the boxes I have done that it said would be louder was. but could be just dumb luck. Cause I haven't done enough of them compared to be a safe assumption

 

[helotaxi 5,000+ posts]

WinISD uses small signal T/S parameters and given non-nearfield large room response. A wall is both nearfield and small room. The plot isn't going to be accurate in the slightest.

For the SPL plots, it's all going to depend on how you set it up. If you tell it to run the same power to the 6.5 and the 18 then it will go with sensitivity but it will limit stuff on the max SPL plot for power handling. The other thing to consider is freq involved. The 6.5 just isn't going to have the low freq SPL of the 18 and is going to hit Xmax sooner. If you know what you're looking at, it's a good tool, if you don't...

 

[vehementSPL 10+ year member]

Well it for sure seems you know more about box programs than I do. But i am 100 percent positive the wall in the taurus and explorer and explorer all peaked within 1 hz of what the program said it would. could just be luck