Subwoofer Drivers

neekomax · « **on:** 3 Jun 2013, 05:16 am »

(Is this the right circle? If not feel free to move)

Hello earthlings. I have a wee project that I want to get going, and I was wondering if any of y'all had any thoughts about which 8" subwoofer drivers are worth considering.

Also, do you think dual opposed woofers in a sealed box worth the extra cost and hassle, or is one driver aight? IYO, of course

Thanks and be well.

- Neeko

TrungT · « **Reply #1 on:** 3 Jun 2013, 05:25 am »

I have my eyes on 8" Rythmik servo sub.
2X8" on each side, build in speaker stand.

http://www.audiocircle.com/index.php?topic=112798.0

neekomax · « **Reply #2 on:** 3 Jun 2013, 05:32 am »

Nice, Trung, I'll have to check those out. They require an active design, though, correct?

neekomax · « **Reply #3 on:** 3 Jun 2013, 05:34 am »

Oh yeah, sealed box is 10" x 12" x 22"...

TrungT · « **Reply #4 on:** 3 Jun 2013, 05:42 am »

neekomax · « **Reply #5 on:** 3 Jun 2013, 05:57 am »

Maybe something like this? http://www.parts-express.com/pe/showdetl.cfm?partnumber=295-200

neekomax · « **Reply #6 on:** 3 Jun 2013, 05:58 am »

Or, there's this... http://www.amazon.com/Infinity-Reference-860w-High-Performance-Subwoofer/dp/B002GHBUFY/ref=pd_sim_e_4

Oooh, but mounting depth is tight here. Would have to mount them front and back opposed - kinda wanted the sides.

JohnR · « **Reply #7 on:** 3 Jun 2013, 09:35 am »

Quote from: neekomax on 3 Jun 2013, 05:34 am

Oh yeah, sealed box is 10" x 12" x 22"...

Why does it have to be that specific size? Is this a car install?

neekomax · « **Reply #8 on:** 3 Jun 2013, 02:06 pm »

Quote from: JohnR on 3 Jun 2013, 09:35 am

Why does it have to be that specific size? Is this a car install?

No, the idea is to make a pair of pedestal-type stands to match my speakers, and also build in subs to augment them. They will be driven by the 300 w plate amps in my SAM1s. The point is to spread the output around to three drivers, allowing greater clean SPLs in the bass. Here's a drawing (ignore the 'Infinity' reference for our purposes).

neekomax · « **Reply #9 on:** 3 Jun 2013, 02:07 pm »

So the mounting depth should be under 5", I suppose.

JohnR · « **Reply #10 on:** 4 Jun 2013, 02:28 am »

Quote from: neekomax on 3 Jun 2013, 02:06 pm

They will be driven by the 300 w plate amps in my SAM1s.

Do you have this setup sorted out electrically? You won't be able to just wire all three drivers in parallel, as the combined impedance will be too low for the amp. Certainly with the 4 ohm drivers you linked to. If you put two in series, and then parallel that with the internal SAM-1 driver, and if the SAM-1 driver is 8 ohms, then that will probably work. But if the driver sensitivities in this configuration aren't matched then it won't work well...

I can't help feeling that you'd be better off using separate amps. And larger drivers

neekomax · « **Reply #11 on:** 4 Jun 2013, 02:34 am »

Quote from: JohnR on 4 Jun 2013, 02:28 am

Do you have this setup sorted out electrically? You won't be able to just wire all three drivers in parallel, as the combined impedance will be too low for the amp. Certainly with the 4 ohm drivers you linked to. If you put two in series, and then parallel that with the internal SAM-1 driver, and if the SAM-1 driver is 8 ohms, then that will probably work. But if the driver sensitivities in this configuration aren't matched then it won't work well...

I can't help feeling that you'd be better off using separate amps. And larger drivers

What would you make?

JohnR · « **Reply #12 on:** 4 Jun 2013, 09:46 am »

Quote from: neekomax on 4 Jun 2013, 02:34 am

What would you make?

Well

I'm not really sure what you are trying to accomplish. I'm not saying that your idea can't be made to work, but it needs some careful investigation.

More likely to succeed would be to build enclosures as you suggest and use a separate amp to drive them. Optionally add a crossover/EQ.... however I wonder why not just make a separate sub. A pair of 10s or preferably 12s in a sealed enclosure would give you low-end heft and extension (possibly with some EQ).

You have a pair of solid state amps that aren't being used right now, right? So, you could use those to start with for the sub. For the crossover and EQ there's miniDSP, behringer, etc... Or, you could just use a plate amp with more limited EQ-ability.

I guess it comes down to where you are trying to get to.

jparkhur · « **Reply #13 on:** 4 Jun 2013, 02:02 pm »

I have worked with the servo 8's from GR/Rythmik as well as the 12s and they would work perfect in a dual opposed box as you describe or even same side (questions on vibration though). Each would have the new 300 watt servo amp. This would keep you in bounds with your dimensions for the stand/pedestal for your book shelf speakers. I too am looking at how many 8's i can fit, still while fitting under my speakers. In my direct comparison and the value of the surface area 2 -8's is a little more than a 12 single. I do understand that since you have certain dimensions, you will be unable (it looks like) to go with a side fire 12.

JP

jparkhur · « **Reply #14 on:** 4 Jun 2013, 02:03 pm »

Just looked at your box again.. you could fire the 8's out the front almost with the 10 inches.. .it would be close.. two front fire 8's.. nice... JP

neekomax · « **Reply #15 on:** 6 Jun 2013, 07:13 pm »

Quote from: JohnR on 4 Jun 2013, 09:46 am

Well I'm not really sure what you are trying to accomplish. I'm not saying that your idea can't be made to work, but it needs some careful investigation.

More likely to succeed would be to build enclosures as you suggest and use a separate amp to drive them. Optionally add a crossover/EQ.... however I wonder why not just make a separate sub. A pair of 10s or preferably 12s in a sealed enclosure would give you low-end heft and extension (possibly with some EQ).

You have a pair of solid state amps that aren't being used right now, right? So, you could use those to start with for the sub. For the crossover and EQ there's miniDSP, behringer, etc... Or, you could just use a plate amp with more limited EQ-ability.

I guess it comes down to where you are trying to get to.

The idea here is to reinforce the 8" subs in my monitors with additional subs to cover the same frequency range (20-200 Hz), allowing higher clean SPLs overall by allowing each sub/driver to do less for the same amount of volume. Within such a short distance, the drivers should act as a single bass source. It would also allow me to experiment with a distributed sub array, if I chose to separate the new subs from the SAMs and place them elsewhere, although my in-room bass response is pretty good already, save some dips between 100-200 hz. This is not a big problem I'm told, is probably floor bounce which we don't really hear, and I am also told that floor-coupled subs should take care of it.

So that's the story. Again, I am partial to the passive approach (driven from the SAM plate amps) to start because it saves money and build complication. But my mind is open to other things, of course.

* As far as sorting stuff out electrically - AJ is advising me on that. Which is good, because I know literally nothing 'bout nothing. Hopefully, this will help me learn.

neekomax · « **Reply #16 on:** 6 Jun 2013, 07:20 pm »

Quote from: jparkhur on 4 Jun 2013, 02:03 pm

Just looked at your box again.. you could fire the 8's out the front almost with the 10 inches.. .it would be close.. two front fire 8's.. nice... JP

I am fairly certain that a front firing 8" driver - or dual opposed, front and back - would be no problem, seeing as my speakers of equal baffle width use 8" subs.

Doing a side firing array would allow the use of 10" drivers, so there's that. Also, I think I might prefer the look of a side firing array, so that I avoid different looking drivers arrayed together, but it's a secondary consideration. One issue is the mounting depth required for side firing dual opposed drivers, as I only have 10" to work with. Although I guess there's no real reason I couldn't expand the width of the sub-stands a bit to accommodate.

mcgsxr · « **Reply #17 on:** 6 Jun 2013, 07:51 pm »

For average sized drivers (ie those not used for SPL contests in car audio) a rule of reference is 1/2 driver width for min mounting depth.

Not a hard and fast rule, but you'll likely find that most 8 inch drivers are less than 4 inch mounting depth, and so on up the sizing for woofers.

I have used 8's, 10's and 12's in the past. I like 10's as a compromise, but like 12's overall. Many 8's can get the job done though, no question.

JohnR · « **Reply #18 on:** 6 Jun 2013, 11:29 pm »

Quote from: neekomax on 6 Jun 2013, 07:13 pm

The idea here is to reinforce the 8" subs in my monitors with additional subs to cover the same frequency range (20-200 Hz), allowing higher clean SPLs overall by allowing each sub/driver to do less for the same amount of volume.

It seems that it would make sense to use the same driver that's in the SAM-1 then... do you know what that is?

JLM · « **Reply #19 on:** 7 Jun 2013, 11:33 am »

I like the idea of opposing woofers, like this: http://www.epiksubwoofers.com/legend.html Thought about doing the same (using sub as a speaker base).

But keep in mind that the best placement for speakers and subs are typically not the same. Search AC bass circle for "swarm" and Floyd E. Toole's "Sound Reproduction" where he explains bass waves versus mid/treble rays and the standing waves in a room (like a shallow bath tub). The theory is that you need at least two subs at opposite ends of the room (three or four spread around the room is better). Alternately, here's a slick product: http://www.spatialcomputer.com/page9/page10/page10.html