I have had my 4 x 18" FI sub in place for 4 years now.
Here is the build thread: It is the Christmas Build: http://www.hometheatershack.com/for...fer-build-projects/63366-christmas-build.html
Nobody has been able to answer this question and I have not seen an answer for it anywhere.
It just does not have the mid bass oomph as other super high quality subs with less drivers and smaller drivers. I am a bass SNOB and I can't stand even a tiny bit of boom in my bass. So - explanations that start with - other sub woofers just boom away and just sound louder and with IB subs they are quieter because of no boom are not expected as I have had a large IB sub for years now. I a fully taking this into account. I have Magnepan speakers and can't stand boxy sound either...
I understand that drivers where the volume of air behind and in front of it is greater than 10 x VAS are limited by excursion and not by heat.... I understand that you can't pump as many watts into and IB sub compared to non-IB all things equal...
OK, so... so what? Assuming an IB sub is following the wave front and rising and falling based on the current going through it... Assuming a SEALED sub is doing the same thing....assuming that this test would be within the limits of both the subs. I am thinking that if you took a super slow motion video of them side by side - they would both be moving in unison - when one is up the other would be up - responding to the current....therefore essentially making the same sound pressure differences in the room...
So..... as you turn it up - eventually one of the subs hit it's excursion limits. So, let's only turn it up to just before that happens. I would still think both the sealed sub and the IB sub would be giving out similar sound pressure....
BUT this appears not to be the case. The sealed sub is much louder. I just can't figure out the mechanical reason why my IB sub with twice as much xmax as a sealed sub does not play as loud and does not seem to pressurize the room in the same way. Again, I understand that the sealed sub has the air pressure to help control the cone.
Basically, assuming the an IB sub as a larger xmax - what is the mechanical reason why an IB sub needs more drivers than a sealed sub with smaller xmax? Please don't just say - because a sealed sub can handle more watts because of the back pressure and because of thermal reasons. That does not give me a mechanical reason why that is the case.
Am I being clear? I have just been considering going back to non-IB because of this. I have borrowed a JL audio f113 that has a single 13.5" driver that is boom free, but gives me a ton more mid bass.
The only think I can think of is that the sealed sub's cone may start moving up a curve that would lead it to a much greater xmax...but the air pressure or the voice coil restricts it so it does not complete it's journey to match the voltage going through the voice coil the same way it would in an IB sub. This would mean that the sound is essentially clipped, so to speak, because the driver does not go as far out as it should. Basically, a plot of a sinewave of a sealed driver would cause the sinewave peaks to be flatten out, but have a much faster rise time between and THAT would account for the increase in loudness?????
This has been bugging me for years!!! Please help.
Here is the build thread: It is the Christmas Build: http://www.hometheatershack.com/for...fer-build-projects/63366-christmas-build.html
Nobody has been able to answer this question and I have not seen an answer for it anywhere.
It just does not have the mid bass oomph as other super high quality subs with less drivers and smaller drivers. I am a bass SNOB and I can't stand even a tiny bit of boom in my bass. So - explanations that start with - other sub woofers just boom away and just sound louder and with IB subs they are quieter because of no boom are not expected as I have had a large IB sub for years now. I a fully taking this into account. I have Magnepan speakers and can't stand boxy sound either...
I understand that drivers where the volume of air behind and in front of it is greater than 10 x VAS are limited by excursion and not by heat.... I understand that you can't pump as many watts into and IB sub compared to non-IB all things equal...
OK, so... so what? Assuming an IB sub is following the wave front and rising and falling based on the current going through it... Assuming a SEALED sub is doing the same thing....assuming that this test would be within the limits of both the subs. I am thinking that if you took a super slow motion video of them side by side - they would both be moving in unison - when one is up the other would be up - responding to the current....therefore essentially making the same sound pressure differences in the room...
So..... as you turn it up - eventually one of the subs hit it's excursion limits. So, let's only turn it up to just before that happens. I would still think both the sealed sub and the IB sub would be giving out similar sound pressure....
BUT this appears not to be the case. The sealed sub is much louder. I just can't figure out the mechanical reason why my IB sub with twice as much xmax as a sealed sub does not play as loud and does not seem to pressurize the room in the same way. Again, I understand that the sealed sub has the air pressure to help control the cone.
Basically, assuming the an IB sub as a larger xmax - what is the mechanical reason why an IB sub needs more drivers than a sealed sub with smaller xmax? Please don't just say - because a sealed sub can handle more watts because of the back pressure and because of thermal reasons. That does not give me a mechanical reason why that is the case.
Am I being clear? I have just been considering going back to non-IB because of this. I have borrowed a JL audio f113 that has a single 13.5" driver that is boom free, but gives me a ton more mid bass.
The only think I can think of is that the sealed sub's cone may start moving up a curve that would lead it to a much greater xmax...but the air pressure or the voice coil restricts it so it does not complete it's journey to match the voltage going through the voice coil the same way it would in an IB sub. This would mean that the sound is essentially clipped, so to speak, because the driver does not go as far out as it should. Basically, a plot of a sinewave of a sealed driver would cause the sinewave peaks to be flatten out, but have a much faster rise time between and THAT would account for the increase in loudness?????
This has been bugging me for years!!! Please help.