EHQS12: 12" Driver for $25

WOW! I used two of these for my outdoor sub. Was thinking about building more to give more output. Now it's a no brainer!

Would putting 4 of those in a seal enclosure for a large open rec-room/basement(like 16' by 30' [ish]) sound any good at all? Seems hard to top price wise.

When I modeled them sealed, they seemed to roll off too high for my taste. Though admittedly my goals weren't typical: since they were to be used outdoors, there would be no room gain, and the normally desirable roll-off wasn't desirable for my application. So at this point, I can't really remember if they were bad in a sealed box, or just not good for my specific application. Still, from what I remember, their frequency peak and roll-off characteristic was much less flat than a Dayton HF series driver in a sealed box that I was also considering. They also don't have a lot of excursion (though still quite a bit more than most other cheap drivers I've seen), so putting them in a ported box helped that out a little too. I can tell you that two that two in a ported box gave me PLENTY of output when I was testing them inside the house. But it's amazing how much gain you lose when going outdoors.

But of course, you could always EQ them, and use multiples for the lack of excursion. They certainly don't have the sound of my servo sub, but for $25 freakin bucks, they aren't bad at all. There weren't bad at $40, which is what they were when I bought the first two. This is a great opportunity for anyone who wants to tinker with building a decent sub with very little money. And at $25/pop, I'd definitely consider multiples for those who have the room. Even without adding any more power, you still get a 3db increase for every doubling of cone area & enclosure volume. And the resulting lower excursion lowers distortion.

Four of the single 4ohm variety, wired in parallel pairs, then then the two pairs in series for a nominal 4ohm load. Put those in a ~6.5ft^3 enclosure and put ~500-600W behind them...but the roll-off is pretty steep.

So what you are saying is... Two quad boxes? The price is right

Don't worry, this Electrical Technician can handle the Ohms law on this one.


How steep of a roll off are we talking? I can deal with 35ish Hz and under, and I think my parents would be happier with that too.

Heh, well, "just" four drivers should give plenty of output in a normal sized room. But at this price, I see no reason not to get as many as you can fit. Wonder how these do in an IB.

I have no doubt you know tons more about electronics than me.

Yeah, I'd suspect that after room-gain is taken into consideration, the F3 could very well be in the mid 30s, sure.

So....thirty-two will displace about 30 liters, for just $800 (of course shipping wouldn't be cheap).

Just doing a REALLY quick model using about 2.5 ft³ per driver, this is what the response looks like. As Willd pointed out, room gain will help quite a bit, but I think EQ would still be necessary.

EDIT: Should have just gone ahead & did this the first time. I revised the graph to show what going up to 4.75 ft³ per driver will do for you (the blue line).

So, I could plan to see easy late 30's with room gain and early 30's with some EQ'ing I'm thinking. It doesn't have to be perfect, just has to have some punch, these are cheap drivers and I won't expect them to be the best thing ever. It will just be cool have 2 quad sub boxes in my basement.


I was planning on makeing a nice hefty dual mono subwoofer amplifier once I secure some more extra fundage, and I was going to throw in some minor EQ'ing, so it shouldn't be too bad. There is alot of stuff at http://www.sound.au.com He is a very nice guy and will help you out even on little side projects of your own.

psycho,if you plan on using 8 of those drivers,you could get away with using small sealed boxes and utulize Rod Elliotts AES project to EQ them flat to 20hz.Those drivers have limited excursion but 8 of them should be able to handle that amount of EQ and of course lots of power will be needed.http://sound.westhost.com/project48.htm

Being the "take one for the team" kind of guy that I am, I just ordered six more of these "just to see what shipping would cost". Shipping was $34.18 (to Atlanta). My previous order for two of them cost $12.31 for shipping. With the price drop, the second order had three times as many drivers as the first, yet cost almost exactly twice as much. I'm thinking 8 of these should be sufficient for a little background music during brunch on the deck. Let's see how ugly I can make the second box.

I was thinking about that project when thinking about this

I'm not sure how that would work out on this since I just want 2 mono amplifers. I think that using his sub EQ project might be a better idea when looking at the whole box. I will look into it more once I order the drivers and make the boxes.

Ouch, 100bucks to get 8 shipped to Thunder Bay, Ontario.

I am using this project with 2 12" woofers in separate boxes and each has its own 200watt amplifier.I run my LFE channel into the EAS which outputs to both amps.It can also sum together the left and right channels.

Oh, you live in Canada?

Go the Mach5 route then.

Just FYI, for all you guys, these things ship in master packs of 4, so shipping is reflected as such. If you live in a state touching Iowa, a 4 pack is about $16~$18 on the shipping.

Farther away you get, more expensive, up to about $27 for people on the coasts.

Darin, do I sense a bigger squirrel proof enclosure in the works?

Most definitely. The new box could be a varmit resort I'm not careful.

You know...if you let them in...and then turn it up...they might learn their lesson, I've seen it done to cats.

Heh, yeah, my problem is, being an outdoor sub, it doesn't get regular use. Especially in winter. By the time it gets used, they could have moved in and done their damage. Don't want any dead rodents in their messing up my Fb!! Though with the problem I already have with squirrels in the attic, the bigger concern is them chewing on the surrounds. Is that covered under warranty?

As much as I'd love to say yes....unfortunately, no squirrels are used in the manufacturing process so it'd be rather hard to show that as a defect

That is incorrect. You're halving the power to each driver while doubling the cone area, keeping SPL the same. More drivers gives more headroom, nothing more.

Doesn't doubling of the cone area usually yield a 6db increase, while doubling the power only yields a 3db increase?

There are many variables, but the generally accepted "rules" are that doubling cone area (same thing as doubling the drivers, assuming they are co-located), yields a 3db increase. Doubling power without a change in cone area (assuming you are still within the linear range of the driver) will yield a 3db increase. Doubling the cone area AND doubling the power (same as co-locating two powered subs) yields a 6db increase.

True, only if you connect the co located drivers in series instead of parallel.

halve the power (ie series connection)= -3db

double cone area =+3db

Hmmm, I don't think the two of you are saying the same thing. You are saying two drivers in series would consume half of the power (in total) of a single driver, but produce the same output as the single driver. That is correct. He is saying that EACH driver would receive half the power, keeping the TOTAL power the same, and doubling the cone area, netting no change in output. That is incorrect. If two drivers were wired in series, the total current would be cut in half, assuming the voltage supplied by the amp remained the same. In series, each driver would see half the current, and half the voltage, so each driver would consume one quarter the power of the single driver setup, not half. So total power would be half, as you said, not the same.

Driver output is a product of the square of the area and the square of the velocity. Velocity is proportional to current, which is proportional to voltage (assuming the same driver). So it takes four times the power to double velocity. In this example, we've doubled the area, and halved the power with the same net output.

I meant that his statement of no gain in output is only true if you add the extra driver and connect them both in series.
If you keep the power the same you will get 3db of gain for the doubling of cone area.

Ah, I see. I agree with you, I just thought you were reading his post differently than I was.

And conversely, if you wire them in parallel, you get a 3db boost for doubling the power, and a 3db boost for doubling the cone area. So 6db extra, assuming you had excursion room in the driver, and headroom in the amp.