OB Bass Helpers

Ali Tait · Post by **Ali Tait** » Wed Dec 18, 2013 11:20 am

Been talking to Scott about possibly changing the 15" Alphas in my OB's. Not that I'm unhappy with how they sound, but we always want more..

Though I'd throw it out to the panel to see if anyone has any thoughts/advice?

As it stands, I have a pair of 15" Alphas per side, which cross to a Visaton B200 at 200Hz, 4th order crossover, actively using a Behringer DCX2496.

I now have a pair of Alpair 12P's which will be fitted sometime soon, which has prompted the question really.

I've been looking at the rest of the Eminence range, and there are one or two that look like they would be suitable from my limited knowledge, but I'm not wedded to Eminence if anyone has any suggestions?

Scott has advised that the 12P's be crossed at the same 200Hz, or possibly 250Hz, and that whilst some of the Eminence range might be suitable, some EQ may be required. I might just go for Betas in lieu of anything else, I like how they sound in Nick's speakers - not sure if anything further up the Eminence range would be any better?

What does the panel think?

IslandPink · Post by **IslandPink** » Wed Dec 18, 2013 11:59 am

I can't offer much advice Ali - James ( and Scott of course ) are your best bet for advice here .
I believe the 'Betas' are a small upgrade.
After that, it depends how much you want to spend - I know James is a fan of Bert Doppenberg's BD15's, but they are a lot more money .
If your low-end performance is passive ( ie. not further EQ-d by the Behringer ) then look out for drivers with the right sensitivity and something around 40-45Hz Fs , and a Qts of about 0.7 to 0.85 . That's about as much as I currently know from the bit of OB study I've done recently with advice from James.

simon · Post by **simon** » Wed Dec 18, 2013 1:37 pm

Ali,

I'm currently running my 12Ps in in my Quasar type OBs with the Supravox 285 drivers (thanks Mark!). They work surprisingly well seeing as my only crossover is a 6uF cap to roll the 12Ps off somewhere between 4k and 5k Hz, and the 285s are running "fullrange" up to about 5k. The Supravoxes really are very nice I have to say. A step up from the Eminences in performance, but also in cost.

Scottmoose · Post by **Scottmoose** » Wed Dec 18, 2013 3:07 pm

Me, I like JBL (not as much as some of the old Altec models...) and some (some) Fane gear. But it's not an area I've spent much time with of late. And they don't come cheap, which is why I didn't raise them before. Likewise the Supravox etc. drivers.

Throwing out a general point, you might want to watch out with some of the instrument / pro audio speakers if you're planning on using a low-order XO since most peak up significantly at the top end; might not impact the transfer functions but things will get interesting in what should be the stop-band.

chris661 · Post by **chris661** » Wed Dec 18, 2013 3:17 pm

Hmmmm...

That rather depends: if you're happy to throw a bit of power around and apply eq, you could probably get some output down to 30Hz, whereas I believe your Alphas will drop pretty quickly at 40Hz.

Going the next few Hz down will require some more cone travel, so linear Xmax might end up a concern.

The 3015LF is well-regarded on diyAudio: it has seen lots of use in high-quality PA systems, mostly horn-loaded.
If you wanted a step up, that's probably what I'd head toward. Note that the low Qts will mean a requirement for eq. The smooth midrange response should make integration nice and easy, and the more open frame (compared to the Alphas) would be more ideal for a dipole system, too.

I have a spare Kilomax 15 lying around here that I'd happily lend out to try side-by-side with one of your Alphas.
Again, though, it'd need eq to get the really low end out.
Its a heavy bugger, so getting it over to you might present a challenge.

HTH
Chris

Ali Tait · Post by **Ali Tait** » Wed Dec 18, 2013 6:57 pm

Thanks for the advice so far chaps. I'm pretty happy with the depth of bass I'm getting at the moment, don't find myself wishing for more, just wondering if I could improve articulation and transparency at the bass end without spending silly amounts of money.

IslandPink · Post by **IslandPink** » Wed Dec 18, 2013 7:15 pm

I've been looking around but it's hard to find suitable drivers through a sea of Pro-audio 15" units that'll take anything from 800W to 3000W . You may find it worth looking for s/h classic drivers instead, from Wharfedale or Altec. I can't remember if there's a higher-Qts 15" Altec one, that would be worth researching, as I know the 15" ones I've heard at ETF have the right sort of sound .

Ali Tait · Post by **Ali Tait** » Wed Dec 18, 2013 7:23 pm

Aye, it seems a bit of a minefield. Might just go for Betas, they'll be fine without any EQ methinks?

IslandPink · Post by **IslandPink** » Wed Dec 18, 2013 7:55 pm

Probably ... but of course James/Nick used them with series crossovers, which alter the basic params a little . Are the Fs & Qts about the same for the alpha and beta ?
It would be well worth , if you haven't, digging back through the threads on this section to see what postings James gave on bass driver options in the past.

Ali Tait · Post by **Ali Tait** » Wed Dec 18, 2013 8:16 pm

Alpha Qts - 1.26, Fs - 41Hz
Beta Qts - 0.58, Fs - 35Hz

Qts is lower, but still higher than anything else in the Eminence range that I've looked at so far.

simon · Post by **simon** » Wed Dec 18, 2013 8:21 pm

BTW Ali, I think you'll like the Alpairs

Ali Tait · Post by **Ali Tait** » Wed Dec 18, 2013 8:33 pm

Aye, had them at work on the end of a cheapie radio for a week breaking in. Sounded pretty good!

JamesD · Post by **JamesD** » Wed Dec 18, 2013 10:20 pm

Quick response - for the price nothing beats the Em Beta 15 and it is a real step up from the Alphas in speed, impact and transparancy. Tone is a little better. This is with passive xover and valve amp driving it - active electronics and dsp style xover changes the game so YMMV!

Honestly I don't find much between the Em beta and the Supravox for performance - the Supravox walks over everything else that I have tried for less money for tone and transparacy. The BD15 is reputed to be better - more speed and impact but needs deploying in pairs on a OB which starts to push the price up!

James

Ali Tait · Post by **Ali Tait** » Wed Dec 18, 2013 10:54 pm

Thanks James, looks like Betas are the way to go then.

SimonC · Post by **SimonC** » Thu Dec 19, 2013 7:56 am

Ali Tait wrote:Thanks James, looks like Betas are the way to go then.

I'm feeling very lucky I picked up a pair of Beta's earlier in the year (thanks Al!). I've also got a pair of A12's running in at the moment, just need to decide if I put them in an MLTL (domestically acceptable) or an OB with the beta's (musically acceptable)...

Simon C

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