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SVS PB12Plus/2 or Adire Tempest/Tumult DIY? (1 Viewer)

Eric Ha

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I have the SVS PB12Plus/2, but want to try my hand at a DIY sub. Would a Tempest or Tumult equipped sub get me the flat-to-16hz extension that I'm getting now? I'll use whatever power is needed, but don't want to go any bigger than the SVS enclosure if possible. I also do not need ANY more SPL than the SVS. It's more than plenty. I've read that the Tempest actually has better extension than the Tumult. True? Any suggestions?
 

MikeLi

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Stick with the SVS... I doubt your going to notice much difference... You have a great sub.
 

Eric Ha

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I love the sub, but would like to make one for the fun of it, as well as being able to put a better finish on it than the textured black of the SVS. After building some Adire speakers, I've caught the DIY bug. I don't however, want to lose any performance.
 

Dustin B

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The tricky part for your request is the enclosure size. Bass reflex enclosures are limited by the the output capability of the port around tuning. The larger the port, the more air it can move cleanly, the louder the sub can play around tuning. The problem is the larger you make the port, the longer it needs to be to maintain it's tuning frequency. Very quickly it will become too long to fit in the enclosure.

The Tempest is designed to work in rather large enclosures, and it will take more than one to beat a pair of SVS DB12 drivers.

What could be interesting would be a pair of Ascendant Audio Avalanche 15 ($299 each) drivers in a 5-6 ft^3 sealed enclosure goosed by 1.5-2kW (what this will cost could vary a lot depending on the amp you choose). Add a little EQ to bring up the bottom end and you should have something as loud as a PB12Plus/2 down to the bottom of the last octave that is a little bit smaller. Should also have the potential to sound quite a bit better.
 

Eric Ha

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Thanks Dustin. I could go with the SVS route of multiple smaller diameter port tubes to keep the cabinet size down, right?
 

Jack Gilvey

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The existence of the SVS line makes it difficult to justify DIY from a money-saving standpoint. Unless you have the tools already, you're likely going to spend more for a given performance level, at least with the lower-priced/more modest performing subs. When I got into it, this was not the case. There was no PB10-ISD then. ;)


Not from the perspective of port length. For a given port cross-sectional area (single large or multiple smaller), you need a specific length to tune a fixed box volume (Vb) to a specific frequency (Fb).
 

dave alan

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Dustin's idea...

"What could be interesting would be a pair of Ascendant Audio Avalanche 15 ($299 each) drivers in a 5-6 ft^3 sealed enclosure goosed by 1.5-2kW (what this will cost could vary a lot depending on the amp you choose). Add a little EQ to bring up the bottom end and you should have something as loud as a PB12Plus/2 down to the bottom of the last octave that is a little bit smaller. Should also have the potential to sound quite a bit better."

...is right on the money.
 

Jack Gilvey

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That pair in IB would be even better. I'm running their more modest siblings, the Atlas 15's, as a pair that way and they're astounding. I'm running the 2 Ohm coils in series and have shorted the 4's giving me a 4 Ohm load and a Qtc of ~0.53. A little PE 150w plate amp gets me to 10dB below reference cleanly.
 

Dustin B

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Ah, hail to the IB (Infinite Baffle). If you have an appropriate space and don't mind cutting the hole I'm definately with Jack on this idea. But I'd vote for 4 Atlas 15 drivers instead of 2 Avalanche 15 for this app.

This would be an extra $40 in driver cost, but the amp requirements would be way way less. Oh, and a side benefit if you have the appropriate adjacent space, this sub would be infinitely smaller in room than the SVS (literally :p))
 

Eric Ha

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I'm curious. What would make the Avalanches sound better than db12's? Does anyone know the XMax or other parameters on the db12 driver? What is it's closet comparable competition?

Down the line I may do an IB. I just added on to this room and don't want to start cutting into the floor. My brother may try an IB set-up within the next year, I'll keep those ideas in mind. Thanks.
 

Edward J M

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IB is easy and fun. I recommend it if you have basic DIY skills and the adjacent space.

FWIW, a Vd of 2.5L is a good bet for the dB12. Regardless, as we used to say at the drags, there is no replacement for displacement. If you are going IB, my vote is also for the quad Atlas combo.


Good one, Dustin - pun intended I take it? ;)
 

Dustin B

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SVS dual driver box subs are pretty close to 6ft^3.

I think 2.5L is pushing it a bit for the DB12 displacement. I'd say the Ultra is closer to that than the DB12 is. I'd guess the DB12 at closer to 2L than 2.5L.

The Avalanche drivers are capable of a little over 4L of displacement and incorporate Adire's XBL^2 motor topology which many people are reporting results in very low distortion all the way to the drivers limits. Dan Wiggins, Adire head hauncho has stated a number of times that it would take 3 Tempest drivers to match the clean output of a single Tumult, even though it only takes 2 Tempests to match the Vd of a Tumult. Also sealed enclosure vs ported for my Avalanche recommendation.
 

EdwinK

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Dustin B, are you saying that two cheap Avalanches in a 5-6 ft^3 sealed enclosure could equal (or better) the performance by a PB12-Plus/2 or a PB12-Ultra/2?
 

Dustin B

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Yes. It's no secret that one can build a sub that will beat any commercial design for less money. You just can't be concerned with enclosure size, need the right wood working tools and the time. SVS is the closest you can get to that value level, and if you don't have the time they easily become your best choice IMO.

The Avalanche drivers are anything but cheap. Drivers equivalent to the DB12 in the Plus series subs would retail for well under $200 each. The TV12 driver in the Ultra is an exercise in excess and would likely retail for over $400, but it's still a 12" driver. The Avalanche is a 15" driver and the displacement advantage that affords is not small. If you don't limit enclosure size to 6ft^3, you could build a dual Avalanche 15 that would easily outgun PB12 Ultra/2. And the XBL^2 motor is not trivial either.

Also don't forget that would be $600 for just the drivers, you'd need another $100 for the enclosure, $750-$1600 depending on the amp you choose, and then you still need to add a finish to the enclosure which can vary a huge amount depending on what you go for. SVS has succeeded with their dual driver box subs (specifically the PB12ISD/2 and the PB12Plus/2) in making DIY a tough sell. Building a sub that size of comparable performance will be damn near the same price. But when you don't have to limit yourself to
 

Jack Gilvey

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Would have loved to, but don't have the Vb available in the closet I'm using. I barely make the "legal" definition of IB with a pair. :)
 

Dustin B

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Sorry Jack, didn't mean to imply you should have used 4, although I know you would have if you could have ;)

I just thought 4 Atlas 15 drivers would make a better IB than 2 Avalanche 15 drivers. Cost is almost the same but the Atlas would have more Vd and way more wiring options.
 

Jack Gilvey

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Absolutely agree! More sensitivity, also, so you really could run a plate amp and get insane levels. Since I only have 3600 liters to work with, though, I was actually considering two Avalanche 15's. This would necessitate more power and some boost in the low end, so I need to decide if the extra Vd is worth it. Your thoughts?
 

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