Budget $400. Suggestions for a subwoofer driver for $150???

[Kevin Haskins]

What else do I need to look show for someone to say whether this is correct (for IB), or not?

Looks good.... I don't advocate running IBs without an subsonic filter. The simulations are all fine and dandy but even with high stroke large displacement drivers you can bottom them with 10Hz information. Its an expensive mistake when you find the limits of your drivers by trial and error.

I use a 15Hz-18Hz 2nd order subsonic on all IBs.

[Mazeroth]

I use a 15Hz-18Hz 2nd order subsonic on all IBs.

How many IBs do you have?! :B

[JonMarsh]

I'd say that's a judgement call based on how hard you push the particular system, and how much headroom it has. A tunable subsonic filter is MANDATORY for EBS alignment ported systems, for example, IMO. Experience with 4-12 driver IB's that are not EQ'd in an attempt to force them flat to 15 Hz, and with realistic size living rooms, indicates to me personally that this filtering is usually not necessary, and has audible side effects.

Perhaps ThomasW, the operator of the Cult of the Infintely Baffled, and an experienced IB builder, will have additional comments.

I do understand your concern for protecting a system, which is one reason to take some time matching the amplification to the load, so that one is unlikely to over power the system.

Unfortunately, there is that percentage of users for whom their favorite system setting is "11" on a scale of 1-10....

[zzzz]

Before I start cutting the wood, could someone confirm with me how I need to mount the driver. I plan on gluing the inner and outer baffles (each 3/4" MDF) and bolt the driver into place.

I'm also unsure what diameter bolts I need. Looks like 4mm or so.

Also, if I mount the driver on the front of the baffle ie not flush mounted how far away does the grille have to be?

[---k---]

If your driver has a rubber ring on it, get rid of it. Get some weather stripping from lowes or HD - I like the Automotive/marine grade stuff. Then use either drywall screws to hold the driver in place or 1/4" bolts with t-nuts. I'm a convert to just using dry wall screws. it works and it is so much easier.

But, if you use t-nuts, glue small squares of real plywood to the back of the mdf and then pound the t-nuts into the plywood. t-nuts just don't grab well in mdf.

[Kevin Haskins]

How many IBs do you have?! :B

None... don't even have one in my house. I have done three installs with them though and every one I've used a subsonic filter to keep from having to come back and replace overdriven systems. When your selling or installing something you take extra measures that you may not do for yourself.

I'm just covering my butt and making sure people understand that the drivers are not protected by an acoustic high pass filter like you have in a sealed box. Some people just don't understand that the drivers are much easier to overdrive in an IB setup. I don't want them to learn the hard way.

[whoaru99]

Looks good.... I don't advocate running IBs without an subsonic filter. The simulations are all fine and dandy but even with high stroke large displacement drivers you can bottom them with 10Hz information. Its an expensive mistake when you find the limits of your drivers by trial and error.

I use a 15Hz-18Hz 2nd order subsonic on all IBs.

That's a very real concern if one would get carried away. The amp I have is a QSC PLX3402...

[whoaru99]

That's in the ball park- about 108 dB at 10 Hz, about 115 dB at 20 Hz with 600W total (150 W /driver).

To improve the accuracy of the Unibox simulation, calculate the actual volume you would have to work with for your IB space, and use that as your working volume, not 99,999 liters. The Q will be a bit higher, the Fb a bit higher, and there will be a bit less output in the very low frequencies for this same drive level.

The IB space is the back volume, I assume? If I did the math right, the actual is about 110,000 liters. It's the whole unfinished partial basement...

[JonMarsh]

That's a very real concern if one would get carried away. The amp I have is a QSC PLX3402...

Yes, that's quite capable of overpowering a 4X IB sub with this driver, depending on your wiring configuration. The ideal setup would be an amplifier and VC wiring configuration that limits power to not much over 150 watts per driver. Unless you need 115 dB+, in which I'd go with Kevin and make the infrasonic filter mandatory. I'd suggest using the lower power, though, as you'll be putting much more stress on the drivers for only a few dB more output level.

With the currently available PLX3602, I'd wire the individual VC's in series, and connect two in parallel on each channel. This would give a total stereo max output of ~775 watts, about 190 watts max per driver. That would make full use of your drivers with over 700 watts, compared to the Unibox sim with 600W (do you NEED more than 120 dB above 30 Hz?) and still be fairly safe without external limiting. Otherwise, plan on that infrasonic filter for safety.

[ThomasW]

Before I start cutting the wood, could someone confirm with me how I need to mount the driver. I plan on gluing the inner and outer baffles (each 3/4" MDF) and bolt the driver into place.

I'm also unsure what diameter bolts I need. Looks like 4mm or so.

Also, if I mount the driver on the front of the baffle ie not flush mounted how far away does the grille have to be?

It's always a very good idea to have the drivers in hand before doing any cutting.

[Kevin Haskins]

That's a very real concern if one would get carried away. The amp I have is a QSC PLX3402...

What Jon said.

You guys have to understand... I'm the guy who gets the drivers back that have been overdriven with someone saying "it just broke, I need warranty work!". I have an obligation to give safe advice in terms of installs.

Just a note on power ratings also..... they are not always as reported. Fortunately, the numbers are typically overstated but its terribly difficult to perfectly match an amp to clip in the region where the driver is going to overload. Typically you will be power limited above a certain frequency and excursion limited below (depending on the install). In that case... you may be safe with >30Hz content but the sub killer movie with LOTS of 10Hz information may take out a driver or two even with a lower power amp than you thought was necessary.

Also as Jon stated, typical 2nd order Butterworth subsonic filters with the corner up around 18-20Hz will rob some output. Worse... unless you design and build the filter yourself they are not the most accurate and the corner can vary +/- 2Hz or more. The DSP based systems should allow a steeper high-order subsonic that you can set lower (maybe around 14-15Hz) and they will have less effect on your usable output and give better protection. They are also VERY accurate. I'm designing a variable 2nd or 4th order subsonic for our new subwoofer filter tool and it is dead-on accurate with the ability to dial-in the 4th order filter with great accuracy. That will allow setting it deeper, getting more usable output and better overall protection.

[whoaru99]

No offense taken, or meant to you, but I don't play that game. If I think I wrecked it I don't try to claim warranty or play dumb.

I actually deal with warranty on totally non-related products and I certainly know where you are coming from with the "I don't know what happened; it just broke" line.

Now, sometimes from the customer perspective that's true, but other times it's clearly and obviously not the case. :lol:

I do appreciate all the advice - now I just have to decide to pull the trigger. Been spending $ like a rock star lately so I'm sort of waffling on it. The trusty old Servo 15 is holding me over, but...I've heard and read so much about IB subs...

[ahaik]

Got my XJ-15, it will be some time untill I will build the sonosub for it. That gives me time to shop around for and amp (I prefer to buy second hand) and maybe an equalizer.
I know the Behringer amps are considered good for the task looking at the driver specs, its 600 watts RMS (depends on the application).
So, Behringer EuroPower EP1500 is probably overkill, but the E500 is a little on the low side.
I will appriciate any other recomendations for an amp.

Thanks,
Asi.

[ThomasW]

If you don't mind the fan noise get the EP-1500 and let it loaf along... :T

[Kevin Haskins]

That is a THERMAL rating. About 98% of damaged subs are damaged by driving them past their mechanical limits so your real concern should be matching them to the appropriate box/amp.

With a 300L sonosub tuned to 16-18Hz 500W@4 Ohms will get you pretty much to max output. I prefer to have an amp that will clip right before you can overdrive the transducer. Clipping won't kill it so you end up with a nice safety mechanism built-in via power limiting. You can still kill it under port tuning but your much safer with that low of a tuning frequency.

[ahaik]

That is a THERMAL rating. About 98% of damaged subs are damaged by driving them past their mechanical limits so your real concern should be matching them to the appropriate box/amp.

With a 300L sonosub tuned to 16-18Hz 500W@4 Ohms will get you pretty much to max output. I prefer to have an amp that will clip right before you can overdrive the transducer. Clipping won't kill it so you end up with a nice safety mechanism built-in via power limiting. You can still kill it under port tuning but your much safer with that low of a tuning frequency.

Well, I'm not a kidd and my blasting days are long gone. As long as one of the kids doesn't turn the knob all the way up it will be ok, I will probably keep the sub level on the processor low enough just in case.
I did some modeling using UniBox, but I'm still not sure about some of the features, I need to play with it some more, also Speaker Building 201 is on its way :T
Thanks Thomas and Kevin.

Asi.

[orbifold]

OK, ordered one. Will do a sealed I guess. I'll be watching to hear what develops as to using this sealed or ported. I have a small room, also, I can wait to see peoples' experience--it will be a while till cutting can start.
Great thread, some of you guys should really look into selling cars or something like that!

[zzzz]

Well I just calibrated and EQd the sub with the exodus xj 15 driver. It sounds phenomenal - to me. It's in an ugly 311 Litre enclosure - sealed not ported. I decided to go sealed to increase sound quality as I won't be able to listen very loudly - typically about 60-70 dB.

Tested it out on LOTR: FOTR and the sauron exploding, ring dropping and other early bass heavy scenes were great! Could feel as well as hear the bass. Doesn't hurt (except to my ears) that the sub is right behind the couch in an awkward spot I can't use for anything else.

Too embarrassed to post pics of the sub in it's current finish.

Many, many thanks for all the sage and wise advice I received here!

[Kevin Haskins]

Come on.... we love seeing bare MDF! :-)

[JonMarsh]

The barer the better! :T

[yousuredo2]

well, they are sold out I guess, all I can find now is the 12" xj-12
Any other good deals for large subs ?
the size of box can be large.

[ThomasW]

well, they are sold out I guess, all I can find now is the 12" xj-12
Any other good deals for large subs ?
the size of box can be large.

$235 including shipping is pretty good for an 18".

http://www.soundsolutionsaudio.com/shop/index.php?act=viewProd&productId=153

[Kevin Haskins]

How much stroke does that 18" have?

The Tempest-X will be in stock late Sept-mid October. I've not received a shipping date yet but they should be popping out of the oven soon. Shipped price will be in the $195 area.

[ThomasW]

How much stroke does that 18" have?

Xmax is 22mm

[BobEllis]

Gee Thanks, Kevin. I haven't even done anything with the XJ-15s I just bought...

[Kevin Haskins]

Gee Thanks, Kevin. I haven't even done anything with the XJ-15s I just bought...

You can never have enough subs.

[Kevin Haskins]

Xmax is 22mm

Thats 19.26 cm^3 per dollar. Looks like a good value and a good IB solution since the size isn't so much an issue.

[Curly Woods]

Would the 15" version of the DIY Cable subs (which I have purchased) work in a down firing cabinet or Sonotube setup?

[Kyle Richardson]

Yes, they will.

[Curly Woods]

Thanks Kyle!

[ahaik]

Looking at the XJ-15 driver parameters:

Fs = 25Hz
Qes = 0.673

EBP = 37

I'm a little confused, wouldn't the driver ring a lot ?
Isn't it more suited for a closed box ?

[JonMarsh]

It's best suited to a dipole, IB, or closed box. Ported box must be very large....

[ahaik]

It's best suited to a dipole, IB, or closed box. Ported box must be very large....

Thanks Jon.
I'm just wondering, woulden't a higher Qes means less back EMF and if put in a large vented box there wouldn't be enough cone control and the speakers wouldn't do as good in transitions ?