box rise question

[LBC]

On the contrary...I'm not sure I've saved my past graphs here, but I'll fire up WinISD and my DATS this evening, if that's what your wanting to see...

Software is NOT worthless - (your putting words in my mouth).

I've asserted that a software plot is quite helpful, and stand by that. You obviously have your own methods for planning a woofer enclosure, and that's fine, but I thought we were having a civilized conversation here.

You have the scorn in your voice of someone that's spent countless hours planning something out, and been disappointed with the actual result (such is the life of SPL'er - I know...), but I believe you are referring to conditions way outside the scope of the original question.

P.s. I consider myself political affiliation Independent - will have to save your Obama hatin' for another thread. =)

Posting graphs is only half of the battle. I too can produce WINISD graphs. What I'm not willing to do is go clamp my woofers at all frequencies just to prove you wrong. You're not going to do it either, so it's not to the contrary. Again, what I'm saying is undisputably true yet you're attempting to skew the facts. The software itself is not worthless. The impedence plot IS worthless. In a real-world scenario (as you have admitted) that graph won't represent the REAL impedence plot. You've already admitted it, and you're continuing to argue. I don't really care what the readers of this thread or forum members think about me. We have both proved me correct. i will no longer be responding because any further discussion is as worthless as your impedence plot.

 

[n8skow 10+ year member]

The only thing you've proven is that you have a somewhat short temper, and don't like being disagreed with (in which case the interwebs is gonna be a harsh ride for you, my friend).

Clamping woofers at all frequencies - indeed - that takes some time, and I'm sure you've got other things to do - (besides following up with supporting data)... good thing I picked up a DATS, takes it about 10 seconds... //content.invisioncic.com/y282845/emoticons/graduate.gif.d982460be9f153bb54e5d4cb744f6ae8.gif

For everyone else - here's a couple graphs I grabbed this evening (please forgive the scale between the two being a tad off):

Daily beater box, Impedance plotted in WinISD

WinISD is showing a predicted port tuning around the 34hz area (the lowest impedance dip to the right of the peak on the left) with impedance maxing out around the 58hz area

And here's what the DATS actually sampled in the car - (*a few words about that below the graph)

DATS is showing a similar shaped curve with tuning in the low 30s, and a shift to the left for the upper impedance peak. Why is this? Cabin gain (aka transfer function), as previously mentioned. Different vehicles are going to accentuate/attenuate different frequencies - and thus affect the impedance of the system.

*concerning my note above, this enclosure weighs around 150 pounds, not going to be able to get a out-of-car measurement at the moment. However, based on my experience, the impedance is going to raise slightly, and the peaks shift to that matching more closely the predicted WinISD curve.

So to sum up, top graph - took about 5 minutes of work at the keyboard.

Bottom graph - took about 3.5 hours of box building.

Now is that top graph 'close enough' for planning a box design? I suppose everyone has to decide that for themselves...

Posting graphs is only half of the battle. I too can produce WINISD graphs. What I'm not willing to do is go clamp my woofers at all frequencies just to prove you wrong. You're not going to do it either, so it's not to the contrary. Again, what I'm saying is undisputably true yet you're attempting to skew the facts. The software itself is not worthless. The impedence plot IS worthless. In a real-world scenario (as you have admitted) that graph won't represent the REAL impedence plot. You've already admitted it, and you're continuing to argue. I don't really care what the readers of this thread or forum members think about me. We have both proved me correct. i will no longer be responding because any further discussion is as worthless as your impedence plot.

 

[LBC]

The only thing you've proven is that you have a somewhat short temper, and don't like being disagreed with (in which case the interwebs is gonna be a harsh ride for you, my friend).
Clamping woofers at all frequencies - indeed - that takes some time, and I'm sure you've got other things to do - (besides following up with supporting data)... good thing I picked up a DATS, takes it about 10 seconds... //content.invisioncic.com/y282845/emoticons/graduate.gif.d982460be9f153bb54e5d4cb744f6ae8.gif

For everyone else - here's a couple graphs I grabbed this evening (please forgive the scale between the two being a tad off):

Daily beater box, Impedance plotted in WinISD

WinISD is showing a predicted port tuning around the 34hz area (the lowest impedance dip to the right of the peak on the left) with impedance maxing out around the 58hz area

And here's what the DATS actually sampled in the car - (*a few words about that below the graph)

DATS is showing a similar shaped curve with tuning in the low 30s, and a shift to the left for the upper impedance peak. Why is this? Cabin gain (aka transfer function), as previously mentioned. Different vehicles are going to accentuate/attenuate different frequencies - and thus affect the impedance of the system.

*concerning my note above, this enclosure weighs around 150 pounds, not going to be able to get a out-of-car measurement at the moment. However, based on my experience, the impedance is going to raise slightly, and the peaks shift to that matching more closely the predicted WinISD curve.

So to sum up, top graph - took about 5 minutes of work at the keyboard.

Bottom graph - took about 3.5 hours of box building.

Now is that top graph 'close enough' for planning a box design? I suppose everyone has to decide that for themselves...

You just proved me right.... again. Do you realize that? I haven't shown a short temper at all. You have merely been lying. Now you have proved as such. Im not sorry that I pointed that out. The impedence, the waveform, the peaks, etc ALL are different. The only thing you can say it "at first glance they sort of look similar". Surely you are trolling me and you are not serious.

 

[n8skow 10+ year member]

Lying about what sir?

Your perpetuating this myth that the enclosure can not be planned out virtually before making any sawdust...

My stance from the beginning has been software (in this case WinISD) can give a close enough plot to show where the peaks and valleys are going to be - and thus able to design your box with... WinISD predicted a tuning of about 34hz - and when built to the same specs, the real-world box had at tuning of 32hz (in-car)... 2hz difference - pretty dang close. As I mentioned, I can't pull the enclosure out of the car at the moment, but plotting the response again in the open - the curves are going to be even closer to the projected... What part of this are you taking so much issue with?

 

[LBC]

Lying about what sir?Your perpetuating this myth that the enclosure can not be planned out virtually before making any sawdust...

My stance from the beginning has been software (in this case WinISD) can give a close enough plot to show where the peaks and valleys are going to be - and thus able to design your box with... WinISD predicted a tuning of about 34hz - and when built to the same specs, the real-world box had at tuning of 32hz (in-car)... 2hz difference - pretty dang close. As I mentioned, I can't pull the enclosure out of the car at the moment, but plotting the response again in the open - the curves are going to be even closer to the projected... What part of this are you taking so much issue with?

I made the statement that the real world impedence curve cannot be calculated.... not what you are trying to frame my argument as. Everything you have thus far posted has confirmed what I've said. You are continuing to behave as though you are correct in saying I was wrong. Thus you're lying to save face. You have proven yourself wrong several times. You have accused me of being mad when I'm not. not even close to mad actually. I find your whole charade to be quite entertaining.

Also, winisd predicts the impedence to be highest at the peak frequency of the enclosure. The impedence spikes sub-30 on both of your graphs there. On the winisd prediction it assumes 5.2 ohms. On your "real world" measurement you get to exactly 4 ohms. The winisd predicts about 28hz. "Real world" is about 24hz. You have cited 2hz but your graphs show otherwise. Also the slopes, the bandwidth between peaks, EVERYTHING is different. It not just slightly off. It's quite far off. They simply look similar at first glance. You either have absolutely no idea what you're talking about or you're trolling. I haven't figured out which yet.

 

[n8skow 10+ year member]

Nothing in my argument has changed since post #11 ... whatever your implying I'm trying to cover up isn't making any sense. We both agree it's not going to be a PERFECT match. I simply pointed out it was going to be REASONABLY close. What you are arguing is a philosophical discussion on what constitutes 'reasonable', which I'm not going to get drawn into.

As I explained - the bottom graph is an 'in-car' reading (which affects the results).

The 'out-of-car' reading will be even closer to the WinISD plot.

The 2hz off I was citing is at port tuning - your looking at the curve below tuning - and yes, it's a bit further off (the 4hz you've pointed out). That's a pretty reasonable margin of error, wouldn't you say? (Again, 5 minutes vs. 3.5 hours... I'll still take option number 1.)

You still haven't disclosed your method for box planning, or shared any notes from your numerous builds to show why this method is so unusable.

In fact, didn't you duck out of this conversation 5 posts ago?

 

[n8skow 10+ year member]

Here are the two graphs superimposed over each other - and corrected for scale.

The biggest discrepancies actually being in the higher frequencies - where the transfer function of my vehicle is having a big impact.

Outside of the car, the peaks in the blue curve (DATS real-world recording) are going to move up a bit - and shift to the right.

I'll see if I can get the enclosure pulled out this weekend and snap another screenshot if your interested in discussing this further...

 

[quackhead 10+ year member]

so my buddy says that the smaller the box the less the rise and the larger the more rise.. is this true?

in my modeling software, it shows impedance rising with a bigger box, but not very noticeable inside of 1 cube increments, what is noticeable though are the change in frequencies at which peak impedance rise occurs above and below tuning on a ported enclosure as vb increases or decreases.

 

[n8skow 10+ year member]

What program are you using? What woofer(s) are you modeling for?

I'd be interested in seeing your results.

in my modeling software, it shows impedance rising with a bigger box, but not very noticeable inside of 1 cube increments, what is noticeable though are the change in frequencies at which peak impedance rise occurs above and below tuning on a ported enclosure as vb increases or decreases.

 

[quackhead 10+ year member]

What program are you using? What woofer(s) are you modeling for?I'd be interested in seeing your results.

I just pulled up a SSA ICON 15 D1 on winisd in 3 cubes tuned @30hz, it shows @ 1.9 ohms rise at tuning, the pre tune spike is at @ 48hz...same sub in 5 cubes @ 30hz, it shows @ 2.2 ohms rise at tuning and the pre tune spike is at @ 44hz..

 

[LBC]

Nothing in my argument has changed since post #11 ... whatever your implying I'm trying to cover up isn't making any sense. We both agree it's not going to be a PERFECT match. I simply pointed out it was going to be REASONABLY close. What you are arguing is a philosophical discussion on what constitutes 'reasonable', which I'm not going to get drawn into.

It's not a philosophical discussion. If you care what your rise is(spl only as it varies with frequency and is only necessary to know when you're playing but 1 frequency and NEED it to rise because you're wired uber low), being off at all is unreasonable. It's the difference between killing your amp and it performing normally. Logic > You.

As I explained - the bottom graph is an 'in-car' reading (which affects the results).

The 'out-of-car' reading will be even closer to the WinISD plot.

Out of car matters for nothing. It will never be played there is and completely irrelevant.

The 2hz off I was citing is at port tuning - your looking at the curve below tuning - and yes, it's a bit further off (the 4hz you've pointed out). That's a pretty reasonable margin of error, wouldn't you say? (Again, 5 minutes vs. 3.5 hours... I'll still take option number 1.)

You're claiming that you're getting an impedence peak at just below 30hz and this peak is BELOW tuning? I just want to be clear. You said you wouldn't get involved into a "philosophical debate on what is reasonable" yet you just asked me if being off 2hz is reasonable, even though 2hz is not relevant to the discussion. It's clear that you're full of it and trying to save face.

You still haven't disclosed your method for box planning, or shared any notes from your numerous builds to show why this method is so unusable.

In fact, didn't you duck out of this conversation 5 posts ago?

I told you I wouldn't disclose any of my notes on page 1. I did say I wouldn't be back. I changed my mind. I did just win a World Title in SPL Sunday. Does that count for anything?

 

[keep_hope_alive Premium Member]

In the battle of

LBC

vs.

n8skow

decision:

n8skow

reason:

provided data

maintained a mature attitude

I did just win a World Title in SPL Sunday. Does that count for anything?

nope. in this thread your title means nothing. people who don't know you don't believe you until you produce data with documentation.

calculations are only as good as the assumptions you make to derive them. all calculations have assumptions. from your posts, it sounds like you don't understand what is happening and you just use trial and error and get lucky occasionally - which is true for most SPL competitors. if you understood, you would just apply the necessary corrections to the software predictions.

you are welcome to provide results and data to support your claims. your experience is not trivial, the question is if you have been paying enough attention to make it matter.

hell, just write your own modeling software.

it's ok to not understand the physics behind sound propagation at low frequencies in an enclosed space. have you ever solved wave equations? they are a PITA, and developing them takes much longer than 3.5 hours. you could spend 40+ hours developing an accurate prediction for the specific vehicle... if you love physics.

as to the question - is software modeling useful when SPL is the goal? yes - if and only if you understand what will happen once installed in the vehicle and correct the response curves for it. with enough experience and testing you can predict what the vehicle will do to impedance seen by the amplifier. or you can just use trial and error.

the use of tools to measure impedance once installed and compare to predicted is handy, and after a dozen or so iterations you may notice a trend that could be curve-fit - thus increasing accuracy.

 

[goingdef 10+ year member]

I would only rely on rise at one tone and for competing as for daily the last amp I tried to predict rise with caught fire while playing music and was producing less then rated power when it did it! so if rise and maximum output are that important to you look into an amp that supply's rated power across a wider impedance range.

 

[LBC]

In the battle of LBC

vs.

n8skow

decision:

n8skow

reason:

provided data

maintained a mature attitude

nope. in this thread your title means nothing. people who don't know you don't believe you until you produce data with documentation.

calculations are only as good as the assumptions you make to derive them. all calculations have assumptions. from your posts, it sounds like you don't understand what is happening and you just use trial and error and get lucky occasionally - which is true for most SPL competitors. if you understood, you would just apply the necessary corrections to the software predictions.

you are welcome to provide results and data to support your claims. your experience is not trivial, the question is if you have been paying enough attention to make it matter.

hell, just write your own modeling software.

it's ok to not understand the physics behind sound propagation at low frequencies in an enclosed space. have you ever solved wave equations? they are a PITA, and developing them takes much longer than 3.5 hours. you could spend 40+ hours developing an accurate prediction for the specific vehicle... if you love physics.

as to the question - is software modeling useful when SPL is the goal? yes - if and only if you understand what will happen once installed in the vehicle and correct the response curves for it. with enough experience and testing you can predict what the vehicle will do to impedance seen by the amplifier. or you can just use trial and error.

the use of tools to measure impedance once installed and compare to predicted is handy, and after a dozen or so iterations you may notice a trend that could be curve-fit - thus increasing accuracy.

Thanks for your opinion. The fact still remains that there is nothing available that can accurately predict impedence rise. The example provided was wrong. If you relied on it and went full tilt for spl you would blow your amplifier. Testing and "getting lucky" would be COMPLETELY required given his examples. So you defeated yourself with your argument and your "vs" statement and conclusion was biased and your assessment of maturity shows your lack thereof since I have done nothing immature. You provided no evidence or factual information which by your definition means you're wrong and should butt out. What you just said was that even though his data proved him wrong, and I showed that, that since I didn't provide any evidence (i didn't need to because his supported my argument) that I'm still wrong and he's right.

 

[quackhead 10+ year member]

Thanks for your opinion. The fact still remains that there is nothing available that can accurately predict impedence rise. The example provided was wrong. If you relied on it and went full tilt for spl you would blow your amplifier. Testing and "getting lucky" would be COMPLETELY required given his examples. So you defeated yourself with your argument and your "vs" statement and conclusion was biased and your assessment of maturity shows your lack thereof since I have done nothing immature. You provided no evidence or factual information which by your definition means you're wrong and should butt out. What you just said was that even though his data proved him wrong, and I showed that, that since I didn't provide any evidence (i didn't need to because his supported my argument) that I'm still wrong and he's right.

U mad, bro?

he mad.