Candidates for ELF performance?

[crazycody1993]

I want to build a small sub i can use in my bedroom, but want to build something thats powered with an ELF style response, preferably a small sealed enclosure.

I dont have anything really specified yet, i'd like to keep it small, but make it powerful enough to have output and performance like the velodyne DD series.

I have yet to build an amplifier and circuit for it, because i want to make sure i get the first part right, being the driver and enclosure combination!

Does anyone have ideas on what drivers would work well for something like this?

[weltersys]

Originally Posted by crazycody1993

I want to build a small sub i can use in my bedroom, but want to build something thats powered with an ELF style response, preferably a small sealed enclosure.

I dont have anything really specified yet, i'd like to keep it small, but make it powerful enough to have output and performance like the velodyne DD series.

I have yet to build an amplifier and circuit for it, because i want to make sure i get the first part right, being the driver and enclosure combination!

Does anyone have ideas on what drivers would work well for something like this?

A high power (>1000 watt), large Xmax (>18mm), low Fs (<25) driver with a 30-40 pound ceramic magnet structure will get you in to a similar response ballpark to the Velodyne DD series.
The Velodyne DD specs don't mention SPL levels, just equalized frequency response of +/- 3dB 18.7 -120 Hz for the 10" to 14.4 -120 for the 18".

Those specs can be reached by many drivers with lesser specifications at lower levels.

A DBX DriveRackPa can do most of the electronic functions, as could Mini Dsp.

The SpeakerPower Torpedo SP-4000 would be a great amp choice if you opt for very high power, it does an honest 4000 watts at 2 ohms, has a good sounding limiter, and a built in crossover.

The VLF SPL level you want will determine the cost of your project.

[crazycody1993]

Well those are a lot larger then I had anticipated! I wasn't looking at going to that large of an extant, I was thinking of building something closer to the ~500 Watt range. Wasn't looking for any extreme SPL's. Just something to add nice low end in the bedroom.

Maybe a 10 or 12?

[weltersys]

Originally Posted by crazycody1993

Wasn't looking for any extreme SPL's. Just something to add nice low end in the bedroom.

Maybe a 10 or 12?

8, 10, 12, 15, 18, 21, whatever. Given the same Xmax, the bigger the speaker the more LF output and the larger the box required.
Parts Express has many subs to choose from, and kits too.

[crazycody1993]

So what would you use for low to moderate listening levels? And for the bedroom, I feel like 25 Hz is a reasonable target?

[StigErik]

If you want to build a true ELF, you must put the system resonance above your XO frequency. That means drivers with high Fs and very small boxes, which again means you need lots of power and drivers than can handle it.

I made a pair that was very good with two Beyma 12P1000nd woofers in a 35 liter cube. I put one driver on each side. DCX2496 for XO and EQ, and 2x250W class-D power. Works very well.

[crazycody1993]

What's the advantage to building the resonance higher then XO?

[StigErik]

Flat group delay and no resonance in the frequency range of the subwoofer. Also predictable 12 dB/oct rolloff.

[weltersys]

Originally Posted by StigErik

If you want to build a true ELF, you must put the system resonance above your XO frequency. That means drivers with high Fs and very small boxes, which again means you need lots of power and drivers than can handle it.

There are many ways to achieve extended low frequency, the approach you (and Bag End) employ is one of them.
High Fs drivers typically don’t have much Xmax, so have much less LF output potential than similar size boxes using low FS, high Xmax drivers.

[weltersys]

Originally Posted by crazycody1993

So what would you use for low to moderate listening levels? And for the bedroom, I feel like 25 Hz is a reasonable target?

“Moderate level” is a relative term, someone used to 140 dB at 25 Hz in their car might think 120 dB of LF is moderate.

I am using an 8” woofer in my kitchen, it can put out around 110 dB (but not down to 25 Hz) at 1 meter before my tuner sub output clips.

A 10” Tang Band WT-1427G would probably be adequate for your bedroom use, you can compare specifications of multiple woofers easily here:

http://www.parts-express.com/resourc...tion-guide.cfm