Uh oh... more subs to test... 15" RS

[cjd]

15" RS Subs

[JonMarsh]

Hey, you heard it here first, back in January!!

Mmmm, might make a really tasty dipole sub, huh? I wonder how real the 90 dB SPL sensitivity is? Wonder how flat it is to 300 Hz? Inquiring minds want to know....

Thanks for the heads up. 30 lB. Not light. Maybe a single 15 in an Arvo Grande Ultima Venti Uno? :B Have to try modeling that...

[SteveCallas]

A pair of the 15" Hi Fi's in ~600 liters tuned to ~16hz with 500 watts, albeit large, looks great for a <$500 subwoofer. That's not much power for some decent output and distortion would be very, very low.

[cjd]

I'm already wondering if these would be as good as anything to replace/upgrade my IB. I have issues with the two Dayton 15" IB subs, and I'm disappointed in the limited XMax on these (14mm for the HF) but... for IB, can you do better for the price?

C

[Jack Gilvey]

Cool, good to see. A single HiFi in a .7 sealed looks sweet, unassisted F3 of ~32Hz and 250w will pretty much max it out down low.

[SteveCallas]

but... for IB, can you do better for the price?

How many would you be using? The somewhat low output would warrant probably at least 4.

Maybe a single 15 in an Arvo Grande Ultima Venti Uno? Have to try modeling that...

Using one or two of these to create a true full range speaker would be awesome :E

[cjd]

Steve, I have 2 of the Dayton IB subs (18mm XMax IIRC) right now - room is fairly small (~1500 cu/ft total enclosed volume with the stairs, but...)

I would likely be building to accept four. Even considering what else is out there, I'm just pondering excursion per dollar as well as sound quality, which is what drove my question. They're probably not at the top of the list for displacement/$ though, so something else is still likely a better route. Maybe.

But, this will have to wait as there are way too many other things going right now to suck up my spending money (finally getting back into photography since digital is to the point where it's good enough to satisfy most of my needs at a price I can now afford...)

C

[ThomasW]

There are three different 18"s currently being created for the IB subwoofer fans...so stay tuned.

In addition TC-Sounds is tooling up for production of an 18".

[Scott Simonian]

Yes!!!

Im gonna go play with these in Unibox right now.



EDIT: Is the Le really just 1.0mH? I know these are the RS line just didn't know if 1.0mH is just a "fill-in" number.

Oh man...for my home use, 1100 box with four RS15's, 200w each tuned to 15hz. F3 @ 20hz and 116dB around the tune. Freakin' awesome!

[Dennis H]

Those look great for an IB. About the same $/liter as the RL-p15, the T/S params (Fs 18Hz, Qts .42) look better, and they should be more efficient. They have the same published Xmax as the IB15 and the real useable Xmax should be higher.

[Mark Seaton]

Hmm... After inputing the numbers into a model, the HF appears like what I expected, and a nice balance at that. What is very interesting is the HO. I'm curious if either the Vas or the Fs are off. The current parameters indicate a motor with almost 45% more strength(N/W) than the HF and an Mms approaching 400g.

Now the increase in Le from 1.0mH to 1.9mH for the same DCR does suggest a lot more wire on the voice coil, but that's a pretty huge jump. If the numbers are correct, that driver will be useful for a lot more than just car audio...

[Amphiprion]

N/W is (BL)^2 / Re, correct?

[Mark Seaton]

BL^2 / Re = N^2/W which is often referred to as a "force factor."

Taking the square root of that, or BL/sqrt(Re) gives you N/sqrt(W).
Neither are perfect metrics, but the latter gives better relative force comparison between motors as you can compare the case for 1W.

[mazurek]

Taking advantage of the commotion...

Can anyone point me to RS 10" HF distortion tests, or just give a simple yes, they are also awesome. These drivers can be hard to search for because people like calling them by slightly different things.

[cjd]

Mark - I'm guessing it's a shared motor still - you get similar results running the 10" or 12" HO vs HF?

Just curious. I can barely grasp what you're talking about anyhow (partly because I am not taking the time to think it through right now... work, you know?)

C

[Mark Seaton]

Hi C,

In looking over the parameters again I probably had slightly over-estimated Sd, which makes things a little more reasonable, but the delta between the two is still there.

Thanks for suggesting to make the same comparison for the 10/12". With the 12" showing roughly 40% increase in motor strength from HF to HO. Since the two motors likely share the same metalwork and magnets, it appears in all of the sizes the HO version is simply a change to a stiff susspension and a heavier guage and more layer winding. The fact that Re stays the same while Le goes from 1.0mH to 1.9mH tells us there is just shy of 2x the wire in the gap, which would make sense with a 2 vs. 4 (or 4 vs. 8 - less likely) layer coil, with the lesser Xmax of the HO and therefore shorter coil accounting for it not quite doubling.

This all makes sense. I was just quite surprised by the resulting Mms which must be in the 345-375g range for the specified Fs and Vas. I guess that's why they need such a stiff spider. That much motor strength and mass make for some interesting options in terms of bass from smaller boxes. It would be even more interesting if the suspsension wasn't so stiff, but it's not a deal-breaker. Of course most DIYers here are looking for most bang per buck, which comes from drivers optimized for larger boxes like the HF model.

[JonMarsh]

Yeah, that's the real trade-off- but the HF is also pretty reasonable for dipole designs, and the lower Le extends the upper frequency working range and reduces inductivity modulation related distortion.

I'm really glad they offer both versions of these drivers- gives the DIY guy a lot more flexibility.

[Mark Seaton]

Oh, I fully agree with the usefulness of both. What is nice that with a larger driver and overall bigger motor the differences are even more pronounced, and I would dare say more useful. Indeed, I very much like low Le of the HF. Shorting rings are great and all, but the problems are easier to deal with if there isn't as much L to start with (which is why I suspect the 2 layer coil for the HF). I was rather happy with the 12HF I used for a custom project this winter. These two look to be a nice addtion to the bag-o-tools & tricks.

[mazurek]

Not sure if you were debating construction of 12 or 15" version. Acoustic-visions has a slightly more detailed description of reference series construction than the parts-express site.

http://www.acoustic-visions.com/~acoustic/products/subwoofer_drivers/dayton_rs12/

[Jack Gilvey]

Looks like a thicker cone also on the HO.

What are we estimating for Sd? I used 750cm^2...just 'cus.

[Amphiprion]

BL^2 / Re = N^2/W which is often referred to as a "force factor."

Taking the square root of that, or BL/sqrt(Re) gives you N/sqrt(W).
Neither are perfect metrics, but the latter gives better relative force comparison between motors as you can compare the case for 1W.

Mkay, good - i tried working it out after i posted and I couldn't get it to work. Glad that I didn't considering (bl)^2 / re != N/W

[Scott Simonian]

Jack - I used 780cm^2 but maybe I went a bit big. Some 15s seem to have a smaller Sd and Im not sure if this is one of them or not. The Ascendant Arsenal are all oversized so the 15 is closer to 800cm^2.

So I just went with a "middle" number.

[Jack Gilvey]

Sounds good, Scott. Wonder why they don't publish Sd?

Although it's a relatively more expensive option, I'm still leaning toward a pair of 12" HF as opposed to a single 15" HF. Smaller box for a given Qtc, albeit with a somewhat higher f3, and I like going with opposed drivers.

[Scott Simonian]

Ah, sealed I see. I need something for an upgrade in my HT so Im going vented. Changed my Sd around from 750 to 775cm^2. Didn't change much other than how fast the excursion gets used up.

My only complaint about this woofer is I had hoped that the SPL might be a little higher. In the alignments that I have played with I could only get away with about 200w or less each. But Im trying for a BIG, vented box. Prolly around 300liters per 15.

So does anyone know for sure that the Le for this driver is just a flat 1mH?

[JonMarsh]

That's just it- unlike the inductors we use in crososvers, Le tends to be frequency dependent in drivers. The measured curve will tell the story.

I'll check my piggy bank. May be I should order a couple to play with. It's just that I know I'm going to be spending so much time in aircraft far away from home over the next two months, it hardly seems worthwhile to get them in now.

[Jack Gilvey]

That's just it- unlike the inductors we use in crososvers, Le tends to be frequency dependent in drivers. The measured curve will tell the story.

That's why spec'd Le is usually done at 1kHz...it gets worse down low. What'd the curve look like for the 12" HF (don't remember seeing anything on Le)?

[Scott Simonian]

That's just it- unlike the inductors we use in crossovers, Le tends to be frequency dependent in drivers. The measured curve will tell the story.

Okay, I see. Im still learning. If you find such a measurement online, link it over here plz.

That's why spec'd Le is usually done at 1kHz...it gets worse down low. What'd the curve look like for the 12" HF (don't remember seeing anything on Le)?

I don't remember where I saw it (I think it was diyaudio.com...not sure) but the measured FR curve of the HF12 had a negligible Le hump in the upperbass. I was hoping that the 15" version would be similar. The BL graph of the 12" was also REALLY flat.

[Brian Bunge]

Darren is sending me a 15" HO to play with. I'm not sure what exactly I'll do with it. I'm leaning towards picking up a 2nd one and building some sort of "balanced force" dual driver cabinet with them. Possibly in some sort of credenza style cabinet.

[WillyD]

Darren is sending me a 15" HO to play with. I'm not sure what exactly I'll do with it. I'm leaning towards picking up a 2nd one and building some sort of "balanced force" dual driver cabinet with them. Possibly in some sort of credenza style cabinet.

Hey Brian, have the driver yet?

I would love to hear your thoughts.

[Jack Gilvey]

Some CLIO data was added to the product pages. HF looks nice and flat to 1K...

http://www.partsexpress.com/pdf/295-468g.pdf

[Dennis H]

Thanks, Jack. FWIW, Sd works out to 804 cm^2 from their D = 320 mm spec.

[Brian Bunge]

I got the HO driver in last week. I know it's not like the beasts that most people are using around here, but it definitely is a nice driver. I'm still thinking I could use multiples in a credenza style cabinet and get plenty of output. I think 4 of them in 320L with around 1000W of power looks pretty good.

[WillyD]

So you think it is definitley good for the $$$?

[Brian Bunge]

Definitely good for the money. While it's a little low in Xmax, I think the low distortion motor will make it a great performer within it's limits. I think if someone is looking for a small, sealed enclosure sub that doesn't require a kilowatt of power to get it going this driver is definitely a contender. It's not going to win any SPL competitions, but then that was not what it was designed for.

[WillyD]

Definitely good for the money. While it's a little low in Xmax, I think the low distortion motor will make it a great performer within it's limits. I think if someone is looking for a small, sealed enclosure sub that doesn't require a kilowatt of power to get it going this driver is definitely a contender. It's not going to win any SPL competitions, but then that was not what it was designed for.

Aye.

Ive been considering buying two HFs and making a pair of sealed subs for my MTs to sit on.

I can't get the HO to model as nicely...but maybe I am not using unibox correctly.