I too prefer the 15 but in general I am not a fan of highly damped drivers. If you need a little box then the 12 would seem the obvious choice but you will have to go ported to get reasonable bass out of it.
My quick modeling of the 12 indicates that with and extended bass shelf (larger than "normal" box with lower than "normal" tuning to extend bass response) you could get relatively strong output down to about 30Hz but then falling like a rock with 20Hz level down about thirteen dB and off the charts gone by the time you get to the low C of a 32' organ pipe. This box is only a couple of cubic feet so easily withing your size limits and this is an advantage.
Now by contrast the 15 in IB as it is intended gives strong output down to 25Hz only 5dB down at 20Hz and still holding -15dB at 10z. But alas you need a bit smaller box. Your limit was about 3 cubic feet as I recall so in a sealed enclosure of that size we have -5dB at 30Hz and about 14dB down at 20Hz (similar to vented at this freq). However the low C is only down about 18dB compared to more like 22dB in the vented 12". Now the wrinkle is a 3dB bump at about 55Hz. If you are into rock/rap you might actually find that to be a plus. However most would want to tame that.
If you are willing to double the size of the box that bump would be tamed significantly to only about 1dB at 50Hz and the bass is extended significantly. The ideal box is about 10 to 15 cubic feet of course.
Now here is what you could try. Build a 3 cubic foot box for the 15 and put an aperiodic port in it and play with the stuffing and see what you get. You should be able to retain much of the advantage of the sealed box and tame the bump a little bit. Just build a crude box out of scrap and experiment. It won't cost much to try it out and you may just like the results.
Keep in mind that room gain will raise the output on the bottom end somewhat so that you may get significantly better results than the open air results that we have simulated here.
Just another 2 cents from the peanut gallery.
BTW a 5 or 6 cubic foot enclosure doesn't have to be intrusive if you plan it as part of the decor. A coffee table is often used. I happened upon a rather unique way myself. I was able to acquire the wooden mantle frame from a defective electric fireplace. I sealed the joints with caulking and glued in a baffle plate where the heater was and braced it up a bit. I ended up with a bit over 5 cubic feet. I mounted a 12" driver with moderate Q and the performance is rather good for about $30 invested.
mike
My quick modeling of the 12 indicates that with and extended bass shelf (larger than "normal" box with lower than "normal" tuning to extend bass response) you could get relatively strong output down to about 30Hz but then falling like a rock with 20Hz level down about thirteen dB and off the charts gone by the time you get to the low C of a 32' organ pipe. This box is only a couple of cubic feet so easily withing your size limits and this is an advantage.
Now by contrast the 15 in IB as it is intended gives strong output down to 25Hz only 5dB down at 20Hz and still holding -15dB at 10z. But alas you need a bit smaller box. Your limit was about 3 cubic feet as I recall so in a sealed enclosure of that size we have -5dB at 30Hz and about 14dB down at 20Hz (similar to vented at this freq). However the low C is only down about 18dB compared to more like 22dB in the vented 12". Now the wrinkle is a 3dB bump at about 55Hz. If you are into rock/rap you might actually find that to be a plus. However most would want to tame that.
If you are willing to double the size of the box that bump would be tamed significantly to only about 1dB at 50Hz and the bass is extended significantly. The ideal box is about 10 to 15 cubic feet of course.
Now here is what you could try. Build a 3 cubic foot box for the 15 and put an aperiodic port in it and play with the stuffing and see what you get. You should be able to retain much of the advantage of the sealed box and tame the bump a little bit. Just build a crude box out of scrap and experiment. It won't cost much to try it out and you may just like the results.
Keep in mind that room gain will raise the output on the bottom end somewhat so that you may get significantly better results than the open air results that we have simulated here.
Just another 2 cents from the peanut gallery.
BTW a 5 or 6 cubic foot enclosure doesn't have to be intrusive if you plan it as part of the decor. A coffee table is often used. I happened upon a rather unique way myself. I was able to acquire the wooden mantle frame from a defective electric fireplace. I sealed the joints with caulking and glued in a baffle plate where the heater was and braced it up a bit. I ended up with a bit over 5 cubic feet. I mounted a 12" driver with moderate Q and the performance is rather good for about $30 invested.
mike
Oh gosh, This is way over my head..WAY over my head.
Ok, first I like to thank everyone on the input and sorry if I sparked some issues within menbers.
Second, I'm still dicing on the unit to use...I will do more reserch on all this tech talk, and hope to get some nice bottom end.
I mostly listen to jazz and live recordings.
this is the one of the specs that came with the 15.
Ok, first I like to thank everyone on the input and sorry if I sparked some issues within menbers.
Second, I'm still dicing on the unit to use...I will do more reserch on all this tech talk, and hope to get some nice bottom end.
I mostly listen to jazz and live recordings.
this is the one of the specs that came with the 15.
Attachments
nunayafb said:
to be honest i didn't notice that its a 4 ohm subwoofer. i kinda assumed that since its a 15" its a pro-wannabe woofer and pro woofers are 8 ohm. but even for 4 ohm woofer a BL of 10 is too low.
yes i think BL is very important ... but it has to be considered in relation to RE, SD, MMS.
high Qts is merely a consequence of Large SD, high MMS and low BL^2/RE
i have a 15" RCF woofer and a 18" TC Sounds woofer that both have Qts of around 0.25 - 0.3 but RCF achieves it through a combination of moderately high BL (27 @ 8 ohm) and moderately low MMS, while TC Sounds achieves it through BL^2/RE alone ( around 30 @ around 4 ohm )
of course when you overdo it this way you end up with a driver from which it is hard to extract the bottom octave but i think the savings in box size are more important.
the RCF i would say is the optimal driver as it perfectly balances its own cost against the cost of the enclosure that it needs and the amplifier that it needs ... its like an average looking wife who is also well educated and works a decent job
TC Sounds is a very "high maintenance" subwoofer ... its as if its saying "if you think you can afford me you better also get a 3000W amplifier and a bunch of DSP processors to get me to put out bass" ... its like a girlfriend who refuses to work but looks like a supermodel ... its a lot of pain in the neck but if you can deal with it - it can be worth it
and then we have our 15" in question ... my god ! i almost wrote an essay on it that was full of profanity, sexism and even racism ... but i decided not to post it because i was already warned by moderators
"and then we have our 15" in question ... my god ! i almost wrote an essay on it that was full of profanity, sexism and even racism ... but i decided not to post it because i was already warned by moderators "
Wow, good essay.
:bs:
"I have punched the specs into UniBox and on a vented arrangement of 100L I’m getting an Fb of 16Hz and F3 31Hz..does this sound ok??"
I think you'll be more ok with a sealed box rather than vented, for both 12" and 15".
Wow, good essay.
:bs: "I have punched the specs into UniBox and on a vented arrangement of 100L I’m getting an Fb of 16Hz and F3 31Hz..does this sound ok??"
I think you'll be more ok with a sealed box rather than vented, for both 12" and 15".
"sorry if I sparked some issues within menbers."
Dont be, It's not your fault,
And I'm not surprised, I've been reading this site since 2001, And it's not always like this.
People here are friendly and loves peace, Except for some very very insecure few, Who looses control over an online discussion without any reasons.
Dont be, It's not your fault,
And I'm not surprised, I've been reading this site since 2001, And it's not always like this.
People here are friendly and loves peace, Except for some very very insecure few, Who looses control over an online discussion without any reasons.
'No offense intended, but when you say these things it shows you don't know how to design an enclosure."
Non taken and of coarse, no problem.
But if I were to build it, I would use sealed box and electronic augmentation, Like I always do, to save space . The power requirement is not an issue , cause there are plenty of high powered plate amp available.
Non taken and of coarse, no problem.
But if I were to build it, I would use sealed box and electronic augmentation, Like I always do, to save space . The power requirement is not an issue , cause there are plenty of high powered plate amp available.
marchel said:
The 12" seems like a good candidate for an LT, but the 15" would be better sold to some kid to put in the back of his Honda. It doesn't have the motor for an LT and probably doesn't have the excursion.
He could then buy a better driver, paying attention to it's specs this time.
Here is my sub - 2 x 18" driven by a Linkwitz Transform eq'ed 550watt amp.
Sealed, of course, 100 litre box.
Attachments
marchel said:
LT and amplifier power can do nothing to increase linear displacement of the woofer. if you have a large and highly linear driver it will work well in a sealed box with LT, otherwise its going to be weak no matter how much power you pump into it.
here is my LT sub
of course i moved the amp since then, but the sub is still in the exact same spot. also its not me in the pics.
Why is BL important? What is the importance of the relationship with RE, SD and MMS? I keep reading statements from you about this but you wont elaborate as to why, what are the equations or software that you use to determine box size and tuning using the above parameters? I am not going to be convinced based on "I have these two drivers and their BL^2/Re is blah, blah blah!" Anyone on this forum could tell you about the low end reduction of a low Qts driver, it is the nature of an overdamped mass/spring/damper system.
What is this based on? What are the equations used to derive Qts from the other parameters you mentioned? Which one of those parameters factor in the stiffness of the suspension (surround and spider)?
What is the difference between a driver with Bl=50, Mms=5 Sd=50 Re=8...... and a driver with BL=100, Mms=10, Sd=50 and Re=8?
Which of those drivers is better? Why? What size box would they need?
The original poster asked a legitimate question and you are throwing anecdotal evidence at him based on unsound theory. I would gladly study your theories if you could answer any of the questions asked, and convince me you are not making up these "important relationships"
Hmm, maybe I should have vented on you the other day when you insulted everyones equipment in the "System Pictures & Description" post.
-J
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