Eminance 15 beta vs Dayton DC380-8 for OB?

[JonPike]

Just thinking off the top of my head... and couldn't find many threads on the Em 15" that I've heard is popular for the low end in a open box speaker. Saw Nelson's at BAF 09....

Anyway, noticed that the Dayton DC380-8 15" woofer is on Black Friday sale (till Sunday) for almost half price: Parts Express: Featured Categories Black Friday which puts it at $35.

Wonder if anyone has any experience with this one? Qts is lower than the other, have no idea how clean it may be, and how low/high it could go, compared to the Eminence 15b. Might be a nice deal. Time is limited, though!

[chris661]

The really popular eminence 15" woofer is the Alpha 15A, for OB use.

At that price, buy a couple - even if they end up in a sealed/ported sub, you'll have gained something. Generally, higher Qts is better for OB use.

[John Bsuch]

Hello....

The PE 15" could be a interesting opportunity... the way to make the best of this would be to use 2 in parallel... and a fairly large series inductor.... say a 10-12 mh iron core. Baffle width of about 18" and a 6 inch or so average depth slanted back wings.

Your OB operating efficiency will be the same as a single Emi Alpha 15... that is set by your baffle width...( f= & F peak values) but your pair of PE's will work half as hard or be able to play twice a loud. The PE's lower FS is a plus too. Not bad for $70 a pair delivered... (about the same as you wouild pay for one Alpha) assuming you get 4 of them. and... with the extra displacement you can also play about a half octave lower.

Add a typical OB appropriate 8" mid range (there are a bunch of choices) and traditional tweeter.

I have cobbled several different versions of the above... the best being dual Goldwood 1858 18's and all I can say is WOW!... YMMV...

John

[Tea-Bag]

Dual Goldwood 18"s. I have fantisized about that for some time.

[JonPike]

Aha...

Well, interesting in that I just got back from much reading around on Martin's OB projects and other stuff... basically doing the homework I should have done before posting this. I see the benefit of having a Qts of about double or more of a single DC380... though I guess EQ'ing might make up for it.

John's suggestion of doubling them up works, and has other benefits... though compact size isn't one of them. (Hey, I'm spoiled by all the small speaker boxes I've had so far!) Nothing like having vast tracts of cone area to move lots of air...

So, even though it might not be a first choice driver, looks like the Black Friday(till Sunday) sale price is a worthy deal for those considering a big OB build.

[MJK]

Originally Posted by JonPike

So, even though it might not be a first choice driver, looks like the Black Friday(till Sunday) sale price is a worthy deal for those considering a big OB build.

I have four low Qts 15" drivers just like those, they have been sitting in my basement for years after being replaced with Eminence Alpha 15A drivers. The SPL/w/m, Qts, and Xmax are all too low. My advice is to not jump for the low price and get the Alpha 15A drivers for an OB or H frame. Those drivers are not intended for an OB, sometimes the deal is no deal.

[John Bsuch]

Martin...

Good to see your post... your work has been so supportive of OB applications...

But...

One way or the other... you must trade low Q and it's intrinsic efficiency advantage for a higher Q in an OB application. And I will bet you a "C" note that the two PE 15" drivers will out perform a single Alpha EMI 15. Yes you will trade the dual drivers efficiency away to get there.. but using a big inductor will raise the system Q... and the doubling of surface area with equal or greater Xmax will swamp the Higher Q advantage the Alpha offers. The Iron law is the Iron law ... and yes I have played with the Alpha... and yes as a simple single woofer solution in an OB application for low dollars it is hard to beat... but the two PE 15's per side wired in parallel will leave it in the dust when properly implemented... been there and done that!


Best

John

[ra7]

What sort of power are we talking about trying to drive two of the dayton drivers per side?

I'm sort of sitting on the fence too... thinking about buying these.

Edit: Let me add to that... will two per side paralleled mean a 4 ohm impedance?

[John Bsuch]

Power requirements will be set by the usual parameters...

How loud, how deep, how big a room, music content, baffle width and so on.

With all that in mind.... and assuming a dual (parallel) PE OB 15" set up on an 18" wide baffle with 6" wing depth... and the inductor to get this system to play flat into the upper 30's, you will end up around 84 DB/watt at one meter... give or take. So 10 watts will produce 93 db or so... 100 watts about 102. For a stereo pair add about 3 db. Truth be told... you are going to be x-max limited from about 40 hz down. This will be about a 4.5 ohm load in the low end...so if you are using a solid state amp that is a plus.... if using a tube amp... you will be pushing things.

Hope this opinion helps...

[MJK]

Originally Posted by John Bsuch

With all that in mind.... and assuming a dual (parallel) PE OB 15" set up on an 18" wide baffle with 6" wing depth... and the inductor to get this system to play flat into the upper 30's, you will end up around 84 DB/watt at one meter... give or take. So 10 watts will produce 93 db or so... 100 watts about 102. For a stereo pair add about 3 db. Truth be told... you are going to be x-max limited from about 40 hz down. This will be about a 4.5 ohm load in the low end...so if you are using a solid state amp that is a plus.... if using a tube amp... you will be pushing things.

How did you come up with those performance values? What size inductor and how much will it cost? At what frequency and SPL (at what input power) do you hit Xmax? What simulation tool did you use to do the calculations?

I tried modeling what you described this morning and cannot get anything close to what you have stated. Adding an inductor rolls off the response above the lowest frequency so you end up with a hump and no extended bass output (probably one note bass). The mid or full range driver would need to be crossed very low. I could not get bass below 40 Hz with any reasonable efficiency. In the end, I had a hard time even reproducing the response produced by one Alpha 15a in the same sized baffle.

I guess I am still sticking with my original posted recommendation. This is the wrong Dayton driver for an OB.