What happens when two drivers with slightly different specs are in the same airspace?
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THATpurpleKUSH
5,000+ posts
Fuckyou
Glad to see another CSVT enthusiast on here //content.invisioncic.com/y282845/emoticons/suave.gif.858fc102f7646e678ee8af7e1fbc41d1.gif
Moble Enclosurs
10+ year member
Box Designer/Builder
Unfortunately, it is not just about the given specs that will determine the output of this idea. You have it sort of correct when you say they may couple and average, but not all parameters will have a large leniency in volume and port characteristics, so in a sense, the modeling of it may be quite inaccurate, or not far off from a single one being modeled in the same air space. The problem you encounter in some cases is each drivers ability to provide specific frequency limitations for each tone played. What this says is that there will be frequencies where the accuracy of a calculated model will be null due to phase issues and db levels due to mechanical specs from each driver. The normal increased output from adding a second driver is the common known 3db audible increase, but this may vary depending on the specific phase of each driver and when they are in phase and out of phase and by how much.
This can cause small dips and peaks in the entire response that if you have the right parameters and design specs, will be audible. The ones that are inaudible will have an increased amount of low frequency distortion and can possibly, under extreme circumstances, cause a wobble effect depending on the time delay of each drivers contributing response characteristics.
Most effects of this will be inaudible to the common ear, especially when the specs are not far off from each other, but it is unlikely that every specification will be nearly identical, though possible. That being said, I think others will agree that two separate drivers of different parameters are not recommended for those reasons.
One of the possible noticable effects will be tuning characteristics shown through excursion movement. You may notice, if the parameters are off enough from each other, that during the calculated tuning, one will be on key, and one may be off a bit for minimal xmax at resonance in a conventional design and even in tlines. This can be bad because if excursion control is not equal, the ability to determine cutoff is null and the c,calculation of max power applied will limit the in tuned driver to control the xmax limitations of the out of tune driver so not to damage it. So, a possible Loss on output may be needed to operate both under usable conditions.
These, of course, are extreme measures, but possible and too much of a risk when dealing with different specs needing different parameters of volume and area to control response, phase, xmax, power handling, impedance, etc.
Not something I would calculate for though it is possible through testing. And I have done a bit of testing on it already to find a lot of inaccuracies in the calculations to achieve a given response. This was done with two drivers of even the same model with one broken in and one not....with identical results.
Bottom line.....not worth it.
This can cause small dips and peaks in the entire response that if you have the right parameters and design specs, will be audible. The ones that are inaudible will have an increased amount of low frequency distortion and can possibly, under extreme circumstances, cause a wobble effect depending on the time delay of each drivers contributing response characteristics.
Most effects of this will be inaudible to the common ear, especially when the specs are not far off from each other, but it is unlikely that every specification will be nearly identical, though possible. That being said, I think others will agree that two separate drivers of different parameters are not recommended for those reasons.
One of the possible noticable effects will be tuning characteristics shown through excursion movement. You may notice, if the parameters are off enough from each other, that during the calculated tuning, one will be on key, and one may be off a bit for minimal xmax at resonance in a conventional design and even in tlines. This can be bad because if excursion control is not equal, the ability to determine cutoff is null and the c,calculation of max power applied will limit the in tuned driver to control the xmax limitations of the out of tune driver so not to damage it. So, a possible Loss on output may be needed to operate both under usable conditions.
These, of course, are extreme measures, but possible and too much of a risk when dealing with different specs needing different parameters of volume and area to control response, phase, xmax, power handling, impedance, etc.
Not something I would calculate for though it is possible through testing. And I have done a bit of testing on it already to find a lot of inaccuracies in the calculations to achieve a given response. This was done with two drivers of even the same model with one broken in and one not....with identical results.
Bottom line.....not worth it.
- Thread Starter
- #4
Great to be here and awesome cars. A 3L CSVT with LSD would be my ultimate thing of beauty //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif
- Thread Starter
- #5
Whow that was a lot of wonderful information. Much thanks. After thinking about it a lot, I think I will use the drivers but just put them each in their own chamber, tuned to what they should be tuned to. This way it will remove any 'worry' from the back of my mind. One thing I have not done is to fully break in the drivers. Even though they are older, I have not really used them much so I should probably put them through a test CD for a day or so at a medium volume - close the door and ignore any noises //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif Maybe after the break-in, they will be closer in spec.
CAT MAN
5,000+ posts
Banned
you need to start typing with less enthusiasm. It really hurts to read all that.
hispls
5,000+ posts
CarAudio.com Veteran
You've just hit on one of the reasons I argue with "break in" nonsense. Those sort of differences in specs are consistant with manufacturing tolerances from one speaker to the next. I highly suspect you'd never notice the difference if you were to hand select two drivers with precisely the same specs.
Also keep in mind you may not have even gotten accurate measurements when you tested. Run the same speaker a few times and you'll probably get some degree of varience just there.
Also keep in mind you may not have even gotten accurate measurements when you tested. Run the same speaker a few times and you'll probably get some degree of varience just there.
05trailblazer
10+ year member
k33p groaning son :)
would it hurt the subs...
- Thread Starter
- #9
Hmmm I think that breakin is not always nonsense. I have a pair of Vifa P17WJ and Vifa M13SG that were measuring with FS twice as high as they should. After an overnight of near full excursion with a 40Hz test tone, they came within 10% of what the manufacturer claimed. I think sometimes the change can be massive and other times it wont change at all. I think it depends on the driver and what materials were used during manufacturing. The Vifa P17 were registering 69Hz before breakin and they should have been 37Hz. I'm sure that would have been a bit audible (as being bass shy).
I should do what you suggested though and measure each one a few times. I only twice with some small changes each time. I should re-measure now and see if anything has changed.
I should do what you suggested though and measure each one a few times. I only twice with some small changes each time. I should re-measure now and see if anything has changed.
THATpurpleKUSH
5,000+ posts
Fuckyou
Very nice, I could go for the same thing with the addition of a Nautilus turbo kit. Are you on CEG?
Moble Enclosurs
10+ year member
Box Designer/Builder
less enthusiasm? No, that's ok. I'm good with being passionate about my hobbies. I'm sorry it hurts your head though. Maybe read slower?
CAT MAN
5,000+ posts
Banned
i read it when i get to a big screen... but seeing that post on a phone is scary stuff lol
CAT MAN
5,000+ posts
Banned
i read it when i get to a big screen... but seeing that post on a phone is scary stuff lol
Moble Enclosurs
10+ year member
Box Designer/Builder
Break in is not nonsense. Any changes in parameters need changes in design work. You cannot rely on just what is audible. Yes, the degree of change is not a huge deal in what you will hear as much as what physical effects will likely happen, but this is very sensitive to that degree of change that modeling the differences would be too much of a loss in time from what the ear will consider acceptable sound.
It would be tough to argue the presence of the effects when our ears are very forgiving. But in some cases, and by far not all, the changes can make enough of a difference to give you an "off" feeling in the reproduction accuracy. Most will never care about this as again, the ear is forgiving, but as a designer, I cannot leave that to chance. It becomes at this point, a personal preference of accuracy. Not just pure science anymore. So, arguing that it is or is not an issue is at this point irrelevant. But for me, I will always be able to see those differences and correct them, as a designer.
---------- Post added at 11:31 PM ---------- Previous post was at 11:31 PM ----------
Break in is not nonsense. Any changes in parameters need changes in design work. You cannot rely on just what is audible. Yes, the degree of change is not a huge deal in what you will hear as much as what physical effects will likely happen, but this is very sensitive to that degree of change that modeling the differences would be too much of a loss in time from what the ear will consider acceptable sound.
It would be tough to argue the presence of the effects when our ears are very forgiving. But in some cases, and by far not all, the changes can make enough of a difference to give you an "off" feeling in the reproduction accuracy. Most will never care about this as again, the ear is forgiving, but as a designer, I cannot leave that to chance. It becomes at this point, a personal preference of accuracy. Not just pure science anymore. So, arguing that it is or is not an issue is at this point irrelevant. But for me, I will always be able to see those differences and correct them, as a designer.
It would be tough to argue the presence of the effects when our ears are very forgiving. But in some cases, and by far not all, the changes can make enough of a difference to give you an "off" feeling in the reproduction accuracy. Most will never care about this as again, the ear is forgiving, but as a designer, I cannot leave that to chance. It becomes at this point, a personal preference of accuracy. Not just pure science anymore. So, arguing that it is or is not an issue is at this point irrelevant. But for me, I will always be able to see those differences and correct them, as a designer.
---------- Post added at 11:31 PM ---------- Previous post was at 11:31 PM ----------
Break in is not nonsense. Any changes in parameters need changes in design work. You cannot rely on just what is audible. Yes, the degree of change is not a huge deal in what you will hear as much as what physical effects will likely happen, but this is very sensitive to that degree of change that modeling the differences would be too much of a loss in time from what the ear will consider acceptable sound.
It would be tough to argue the presence of the effects when our ears are very forgiving. But in some cases, and by far not all, the changes can make enough of a difference to give you an "off" feeling in the reproduction accuracy. Most will never care about this as again, the ear is forgiving, but as a designer, I cannot leave that to chance. It becomes at this point, a personal preference of accuracy. Not just pure science anymore. So, arguing that it is or is not an issue is at this point irrelevant. But for me, I will always be able to see those differences and correct them, as a designer.
Moble Enclosurs
10+ year member
Box Designer/Builder
lol, yea I don't doubt it. //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif scroll,scroll,scroll, lmao. I typed it on my phone too.
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