Micro Sub using ND105 4" driver

[djkest]

So I keep hearing how the Nano Neos and the NTNs have so much bass. I haven't seen any subwoofer designs with them though. The 4" version actually models better for a sub than the 5.25" version. Well, if you plug a single driver into a ported box calculator, you can get some interesting configurations:

8 Liters: f3 40.5 Hz
10 Liters: f3 36.2 Hz
12 Liters: 33.1 Hz

Port is 1.5" ID 6-7" long depending on box.
Perhaps 2 of these (8 ohm) paired with a dayton 70 watt amplifier would be a great little mini-sub. You could make it as narrow as 6" using 1/2" mdf. I don't think these drivers are suited to bandpass use.

Now this doesn't seem that impressive, but this is before room gain as well. Not sure how to sim 2 drivers. Only real problem is that the neodymium drivers are so expensive right now.

But why would you do this?
Well, you could get a 9L box that would be roughly 6 x 9 x 16" that would fit just about anywhere and produce deep (but not loud) bass.

[XtremeRevolution]

Re: Micro Sub using ND105 4" driver

Definitely not a bad idea, but how much do you really want to pay just to use that speaker when the 6.5" Buyout sub is $8 (if you buy 4 or more).

[djkest]

Re: Micro Sub using ND105 4" driver

Definitely not a bad idea, but how much do you really want to pay just to use that speaker when the 6.5" Buyout sub is $8 (if you buy 4 or more).

That's true- I forgot about those. I'll have to look for threads on the buyout sub.

[Chris Roemer]

Re: Micro Sub using ND105 4" driver

That's true- I forgot about those. I'll have to look for threads on the buyout sub.

Durango?

Don't forget, even though the Xmax is 4mm, the Xlim is 10mm.

When designing, I use 6mm, with a self-imposed 8mm limit.
Before my Nano Neos (although I didn't know it at the time), TTBOMK there were 2 designs using the ND105-4. MZ's "New Horizons", and there WAS a sub built, just like you'rre suggesting.

Chris

[tomzarbo]

Re: Micro Sub using ND105 4" driver

I have built a pair of the original neo nanos and I've played some bass test tones through them. They won't go crazy loud, but in an apartment I wouldn't want anything louder. The bass is satisfyingly deep. I think they would make decent subs, and certainly something to talk about when visitors see them.

I made a small set of mini desktop towers to use as subwoofers for my computer desk, based on Wolf's 'Bass Toaster' design concept. They use TB's 3" drivers, not as nice or deep playing as the Dayton's but they work fine for that application.

I've thought about buying a set of the ND105's to make a small subwoofer with myself. I think it's a good idea, I hope you do it, and take lots of pics!

TomZ

[djkest]

Re: Micro Sub using ND105 4" driver

Using 1/2" mdf do you think 5" external width would be doable, or would that "choke" the woofers?" Cutout diameter is 3.625"

[bmaupin]

Re: Micro Sub using ND105 4" driver

Using 1/2" mdf do you think 5" external width would be doable, or would that "choke" the woofers?" Cutout diameter is 3.625"

that is 1 liter - what do you think ;)

[Chris Roemer]

Re: Micro Sub using ND105 4" driver

that is 1 liter - what do you think ;)

Yeah, what's the point, I don't think the SA25 will fit in a 5" cube anyhow? You're blowing almost 2 octaves. If you want to jamb something into a 5" cube, get a 3" TB on closeout for $9.

For sub duty, you want somewhere between 1/4 and 3/8 vented cu.ft. That's still tiny for a sub that reaches down into the 30's.

Chris

[greywarden]

Re: Micro Sub using ND105 4" driver

When I'm designing an enclosure I usually make the width [driver cutout]+2*[thickness of baffle (up to 0.75")] as a minimum so that you have enough room for the chamfer on the back side. Then I just round up to the nearest 1/4" or so.

[jcpahman77]

Re: Micro Sub using ND105 4" driver

Newb question: What's the difference between Xmax and Xlim, actually, what is Xlim, the difference between the two may become apparent just knowing that.

[Wolf]

Re: Micro Sub using ND105 4" driver

Newb question: What's the difference between Xmax and Xlim, actually, what is Xlim, the difference between the two may become apparent just knowing that.

Xlim or actually "Xmech" is the mechanical limit of the excursion by the backplate, or the fact the suspension will not allow any further travel- period. Don't run things to that point.

Later,
Wolf

[jcpahman77]

Re: Micro Sub using ND105 4" driver

Ok, now I do have to ask, how does that differ from Xmax? I thought Xmax was the mechanical limit of the driver.

[Wolf]

Re: Micro Sub using ND105 4" driver

Ok, now I do have to ask, how does that differ from Xmax? I thought Xmax was the mechanical limit of the driver.

Xmax is the factor of the maximum linear excursion in one direction, which is to the point the Bl product drops by a certain percentage, or mathematically;

Overhung; (coil length - gap height)/2
Underhung; (gap-height - coil length)/2

Usually, it is defined as a one-direction movement, or the added "p-p" for total excursion of both directions.

Later,
Wolf

[jcpahman77]

Re: Micro Sub using ND105 4" driver

I'm sorry, the "Bl product"?

[Wolf]

Re: Micro Sub using ND105 4" driver

I'm sorry, the "Bl product"?

The effect of the motor strength (Bl, usually in Tesla-meters) on the voice coil is lessened the further out of the gap it goes.

This is on standard configuration overhung or underhung drivers. Dual-gaps, varying thickness coils kind of get around this point.

Later,
Wolf