Lothwer OB Eminence Alpha 15As or Augie

[4ndr3]

Hi All

I've obtained a set of PM6As quite a number of years ago, with the idea of going for one of the popular horn designs. Time and lack of woodwork skills put a stop to that idea and resulted in the Lowthers going into storage

However, thanks to this and other forums I've pretty much been convinced OB is the way to go and on the plus side it should be do-able with my almost non existent woodwork skills

But, Lowthers on their own would be a bit bass shy. I believe the trend is to either go with Hawthorne Augies (one each baffle) or else Eminence Alpha 15As (2 each baffle). Coming from a car audio environment, I know how fast and detailed high Q (freeair subs) could be, so with my noob knowledge , I totally agree with MJK in his view on OB + high Q drivers.

So, finally, my question: taken my current kit which is a LEAK Stereo 60, Decware SE34I.2 and the Lowthers, what will be the simplest (read cheapest ) way to integrate some good fast and detailed low end into the OBs? I only have a passive pre-amp in half working condition so I would rather stay with the build in pre-amp in the Decware for now.

I would like to keep the signal path as simple as possible. I was leaning towards pairing the PM6As with two 15As each. Maybe running with the 15As and PM6s from the Decware only although I am not sure how to wire that up to get the most from the woofers: 15As in serial with PM6A in parallel or if the Decware will have the legs to power the lot.

Any case, anybody with similar systems running? Suggestions?

Cheers

Andre

[chris661]

I heard a system with one beta-15A per side (on OB) yesterday.
Believe me when I say that one 15" driver per side can be more than enough. Makes it cheaper for you, too.
If you use a passive crossover at the speaker end, it's easy enough to cross around 300Hz. Probably somewhere near ideal.
You shouldn't need any/much eq with a set-up like that, either.

Chris

[bluemartini]

You may find this thread interesting where Nelson Pass experiments with OB using the PM6As and the Feastrex D9nf's

Feastrex Fun

[rjbond3rd]

According to MJK, he was fighting the efficiency of his Lowthers, and so not only did he have to use two Alpha 15A's per side, he also had to make the baffle extremely wide (60"?) and then on top of that, I believe he had to add bass boost through his active EQ (which I think is a dbx Driverack). But that's because he didn't want to pad down the Lowthers, and that's why next time he deliberately specified a ~90db fullranger.

Next step, I think, would be to decide active or passive on the crossover.

[Godzilla]

I use one 15" Alpha per side and it's plenty when paired with the 93db Tangband 1808. But mine setup powers the woofers with a separate amp.

Boomer Open Baffle Speaker Kit

I can only imagine how powerful and rich two Alpha's per side sound!

Godzilla

[4ndr3]

Originally Posted by chris661

I heard a system with one beta-15A per side (on OB) yesterday...

Chris

Thanks Chris. Was that driving the LF and HF drivers from the same amp? Wonder if the beta-15A would keep up with the PM6A or if it would need/eq or else a bi-amp.

As a starting option I am also trying to get my head around driving two pairs of alpha-15As plus Lowthers from the same amp. Mm, how to present 8ohm by 8ohm by 8 ohm to the amp and still get good SPL from all drivers...

A

[4ndr3]

Thanks for the link bluemartini, (nice link that), and I like the ferarri/lotus elise etc. cars discussion in the thread

[nigelwright7557]

Try a 18 inch Eminence Sigma Pro.
Louds of base at a reasonable price.

[pjanda1]

Andre,

The Augie is not very sensitive at 89 db 1w/1m, so I can't imagine you'd have any luck running them with a passive crossover and a single amp. Nelson Pass appears to have success using higher efficiency woofers with the Lowther, so maybe Alpha 15's would work. I don't know the details of all of their units, but Decware amps often like low impedance loads, so two Alpha 15's could work well.

Don't just look at the efficiency spec for a given woofer, plug the numbers into a box or OB simulator. PA woofers often show significant peaking near the top of their passband, and that skews the numbers up. There are plenty of woofers that have a high number, but will make less noise in an OB than the Alpha.

It sounds as if you are set on the high Qts route. I personally followed Pass's lead, and used a lower Q woofer. I had anticipated needing a bunch of EQ/shelving, but a simple second order slope at 80hz (like NP) seems to be working well (using the miniDSP as an active crossover). My woofers are Foster OEM's (the "Jensen") from Jack Hidley. They are great OB woofers (high sensitivity, high compliance, high excursion compared to most budget PA woofers) and only $60 each. There are certainly nicer woofers out there for bigger budgets, though.

The Augie looks like a nice woofer, but I don't know that it'll do what you want it to.

Paul
Wild Burro Audio Labs - DIY Full Range Speakers

[zmyrna]

Many open baffle gurus think that the woofers mentioned here do "muddy" the mids of drivers Lowther kind. Lowther America settled on Tone Tubbies and Altec designs. Lampizator likes Altecs as well. If two 15" ers seem like overkill for your room, two 12" could be ideal solution for you and integrate better with the Lowther as well.