New subs what do you think?

[jeffsg4mac]

Hey guys, I am thinking about redoing my subs just because I can. Can one or more of you double check my figures and see what you think or suggest. I have worked up with Bass Box pro an isobaric with 2 titanic 12's. Box is 30x17x17 external, slot is 1.5x15.5x46. I get an f3 of 20hz, peak VV 14.7 m/s, everything else looks real good too. Any suggestions or comments would be appreciated.

 

[annunaki]

Hey guys, I am thinking about redoing my subs just because I can. Can one or more of you double check my figures and see what you think or suggest. I have worked up with Bass Box pro an isobaric with 2 titanic 12's. Box is 30x17x17 external, slot is 1.5x15.5x46. I get an f3 of 20hz, peak VV 14.7 m/s, everything else looks real good too. Any suggestions or comments would be appreciated.

Hi Jeff,

What power level did you model the vent velocity with? To ensure you are well out of range I always model with the full RMS of the driver or whatever it will tolerate without exceeding xmax. This way I am sure vent velocity will be a non issue.

 

[jeffsg4mac]

Hi Jeff,

What power level did you model the vent velocity with? To ensure you are well out of range I always model with the full RMS of the driver or whatever it will tolerate without exceeding xmax. This way I am sure vent velocity will be a non issue.

Input was 500 watts

 

[Guiria]

Hey guys, I am thinking about redoing my subs just because I can. Can one or more of you double check my figures and see what you think or suggest. I have worked up with Bass Box pro an isobaric with 2 titanic 12's. Box is 30x17x17 external, slot is 1.5x15.5x46. I get an f3 of 20hz, peak VV 14.7 m/s, everything else looks real good too. Any suggestions or comments would be appreciated.

Just curious, what is the current configuration of your subs? What makes you interested in running an isobarik configuration?

I also have a pair of titanic 12" subs so your thread has immediately caught my interest.

 

[jeffsg4mac]

Just curious, what is the current configuration of your subs? What makes you interested in running an isobarik configuration?

I also have a pair of titanic 12" subs so your thread has immediately caught my interest.

I am running two titanics now. One up front and one and the rear. You can see them here. Boxes are 45x17x15 and have an f3 around 20.5hz. I am just looking to reduce the box size a little. They are big. Isobaric seems like the best way without making any sacrifice and adding a little power handling. Of course if anyone has a better suggestion for these drivers by all means lets hear it.

 

[BoredSysAdmin]

Ever heard expression - if isn't broken - don't fix it

Seriously thou - Didn't you went thru same thing before ??
http://forums.audioholics.com/forums/showthread.php?t=73301&highlight=Isobaric
http://forums.audioholics.com/forums/showpost.php?p=639845&postcount=38

Or is this the time of year to talk about it again ?

 

[jeffsg4mac]

Ever heard expression - if isn't broken - don't fix it

Seriously thou - Didn't you went thru same thing before ??
http://forums.audioholics.com/forums/showthread.php?t=73301&highlight=Isobaric
http://forums.audioholics.com/forums/showpost.php?p=639845&postcount=38

Or is this the time of year to talk about it again ?

I did? I can't keep track of what I was thinking about before, and yeah the weather is getting really nice to be outside making stuff. Not too hot.

 

[Guiria]

I am running two titanics now. One up front and one and the rear. You can see them here. Boxes are 45x17x15 and have an f3 around 20.5hz. I am just looking to reduce the box size a little. They are big. Isobaric seems like the best way without making any sacrifice and adding a little power handling. Of course if anyone has a better suggestion for these drivers by all means lets hear it.

Love your theater room btw.

Seems like each titanic with it's own amplifier channel would have more power than the pair of them in a single sub. If you ran the ep2500 at 2 ohms isn't that too much power for a pair of titanic subs?

Maybe I'm wrong, just asking thought provoking questions to make sure you've covered your bases before you decide to mess with an already ideal setup IMO.

I modeled a single 7.5 cubic foot box at 20 Hz for those subs that shows impressive results in WinISD. If you'd like I can PM you the file. Just another idea. You could make your center channel stand a little bit bigger and run dual 12" up front???

 

[jeffsg4mac]

Love your theater room btw.

Seems like each titanic with it's own amplifier channel would have more power than the pair of them in a single sub. If you ran the ep2500 at 2 ohms isn't that too much power for a pair of titanic subs?

Maybe I'm wrong, just asking thought provoking questions to make sure you've covered your bases before you decide to mess with an already ideal setup IMO.

I modeled a single 7.5 cubic foot box at 20 Hz for those subs that shows impressive results in WinISD. If you'd like I can PM you the file. Just another idea. You could make your center channel stand a little bit bigger and run dual 12" up front???

Thanks,

I am running each sub on it's own channel(onkyo has dual sub outs) so amp is only seeing 4 ohms not 2 and it is stable into 2 ohms stereo or bridged so no bigee either way.

The idea is to reduce box size not increase it. I am thinking about buying two more titanics. I would never just have one sub in the room. You are correct two subs one up front and one in the back give a much better room response then a single sub anywhere in the room. Isobarics let you reduce box size somewhat and still keep your f3 the same or lower as well as increased power handling. Not that I need increased power handling now but smaller boxes would be nice.

To be clear I did not plan on just having only one sub. I would buy two more drivers and start over. The goal being to keep the f3 at 20hz and reduce the box size. I am just wanting someone else to run the drivers and see if what I am planning is a good or not.

 

[annunaki]

Hi Jeff,

One thing to remember is that the efficiency with isobaric drops way off. You need double the power for one isobaric enclosure as what you would with a single sub in a vented application to get the same output.

Yes, you do in fact lower f3 significantly with the enclosure size, but it comes at the cost of efficiency as I highlighted in the last thread about this topic.

I would go with what I recommended last time in the other thread for the isobaric option. Please note my vent size however as it was different than yours.

 

[jeffsg4mac]

Yes, you do in fact lower f3 significantly with the enclosure size, but it comes at the cost of efficiency as I highlighted in the last thread about this topic.

I would go with what I recommended last time in the other thread for the isobaric option. Please note my vent size however as it was different than yours.

Oh jeesh, I forgot about that other thread. What about doing a sixth order box? I have never played with those.

 

[annunaki]

Jeff, are you referencing a sixth order isobaric bandpass enclosure?

If so your degree of complication will greatly increase as well as possible size. You will have multiple vents to contend with also. Being off on volume by as little as .05ft^3 in a 6th order design can throw off tuning & response.

Rough modeling the enclosure does not appear to gain any thing except a larger enclosure size.

 

[jeffsg4mac]

Jeff, are you referencing a sixth order isobaric bandpass enclosure?

If so your degree of complication will greatly increase as well as possible size. You will have multiple vents to contend with also. Being off on volume by as little as .05ft^3 in a 6th order design can throw off tuning & response.

Rough modeling the enclosure does not appear to gain any thing except a larger enclosure size.

Thanks, I was thinking of sealed box with a boost. Never built one and not sure if the tradeoffs are worth it. It is looking like the isobaric bass reflex is the best bet for low end with smaller box though unless you have any other ideas.

 

[lsiberian]

you might look at a P-R build. Not sure if you are are interested, but they do reduce size.