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Open Baffle Epiphany!

Poultrygeist said:
Boomer-Open-Baffle-Kit.jpg
Parts list: For those who have been PM'ing for details.

2 Alphas 15a ( Parts Express #290-407 ) @ $65 each ( sometimes cheaper on ebay )

2 Betsy FR drivers ( Wild Burro Audio Labs ) @ $100 a pair

1 Yung SD200 class D plate amp ( Parts Express #301-504 ) $100

3/4 MDF - $20 ( quality is not as important as with resonant enclosures ) Plywood costs more but can be finished nicel

Boomer-Open-Baffle-Kit.jpg
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Using these parts how would an active crossover, like the inexpensive Behringer Super X-Pro, aide or complicate this setup? Also, will other 2 channel amps work in place of the Yung? If so how many watts are needed to drive the Alphas? Thanks.

cubdog
 
active crossover makes it all easier. you can adjust for the room, when you switch in new drivers, etc. also facilititates bi-amping nicely so you can go SET/PP for the HF and SS for the low.
 
cubdog said:
Using these parts how would an active crossover, like the inexpensive Behringer Super X-Pro, aide or complicate this setup? Also, will other 2 channel amps work in place of the Yung? If so how many watts are needed to drive the Alphas? Thanks.

cubdog
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An active complicates by nature of all the extra cabling. I have a 2 way Behringer and while many people put them down it's been a solid performer. Can't say the same about their 3 way which I returned.

You can use any solid state amp to drive the Alphas when using an active crossover. I think 100 watts should be sufficient.
 
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The cabling for an electronic crossover really isn't that big of a deal unless you're constantly swapping things around. Since I do that everything has to be labeled. XLR or 1/4" adaptors are required to use your regular cables. The 1/4" adaptors are cheap and cost like $5 for eight on ebay. They're the same as headphones jacks.
 
tomlinmgt said:
^^^
Monoprice XLR or 1/4 to RCA are pretty decent cables for about the same price as nice adapters.
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I have some of the Monoprice XLR to RCA's cables and was surprised at their quality for such a low price.

The Behringer active is XLR only so I use the Monoprice cables with it

The Ashly active allows you the choice of either XLR or 1/4" and I used the cheaper 1/4" adaptors with it.
 
Poultrygeist said:
I have some of the Monoprice XLR to RCA's cables and was surprised at their quality for such a low price.

The Behringer active is XLR only so I use the Monoprice cables with it

The Ashly active allows you the choice of either XLR or 1/4" and I used the cheaper 1/4" adaptors with it.
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Do you have an opinion on 1/4" vs XLR, Paul? Or does anyone?
 
1/4" jacks can pull out pretty easy, though in this use that's not too much of an issue. Otherwise, the connector doesn't mean too much. It's the number of conductors and signal on them that matters.

With 1/4", be aware they can be 2 or 3 conductor. TS or TRS...tip and sleeve....or tip ring and sleeve. More typically (and incorrectly) called mono or stereo. And to further make your eyes rotate counterclockwise, can be in the three conductor, either stereo signal or balanced, which don't mix well. Stereo headphones jacks, for instance, are stereo. In this application, you wouldn't be using stereo, though it could be balanced or single ended.

Interfacing XLR with other connectors has it's set of pitfalls too. But overall the way to remember the important is that you can short an input, but don't typically short an output. This "buy an adapter cable thing" is dangerous in my opinion. I've fixed blown outputs many a time over someone miswiring. Unbalanced out to balanced in, no big issue. But taking the balanced out to the unbalanced in, warning...warning....danger Will Robinson! I would never plug one in, from any firm, without using an ohm meter and seeing how it's internally wired and thinking about the wiring at each end of the intended use. Don't short an output! The exception I was leaving is for transformer or servo balanced outs.

The reason this all comes up, on connectors and wiring, is that several of the economical crossovers come from what I call the semi-pro world. 1/4" and XLR are the dominate connectors used. Mixing those into home gear and the unbalanced world can get interesting.

Going through all the issues can sure make you appreciate just the plain ol' balanced to balanced or unbalance to unbalanced connection.

But don't be intimidated...line level crossover and biamping gives big abilities! It can be as easy as a plate amp for the woofer with the signal for the mains going to the amp for them. When you're rolling in the low end, fairly economical has worked pretty well for a lot of people!

EV3
 
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I can't tell any difference. I'm a penny pincher so buying 8 1/4" adaptors for $5 is very appealing. 8 XLR adaptors would cost around 10 times more.

If cosmetics are important the Monoprice XLR-RCA single cables are beefy handsome with nice terminations and very flexible. They aren't color coded so I use red or white shrink bands on them.

I said 1/4" adaptors are like headphone jacks but you only want the one channel version.
 
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tomlinmgt said:
I understand the requirement for (considerable) baffle area for the production of LF, but what is the general rule for recommended baffle area for a driver operating from approx. 125 Hz and up (specifically an Eminence Beta 12LTA)? And am I understanding correctly that no baffle is generally beneficial above 2-3Khz?

Thanks,
Michael
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I think this post slipped through the cracks....bump for re-submission.
 
These Beta 12LTA's are mounted on 18"(w) x 24"(H) baffles. The reason I used those measurements was because they are the same width as the H-frames they rest on and I kinda like my FR's and tweets at ear level.




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I'm thinking a full range aluminum cone driver might have potential in an open baffle. It's sort of a general question. Are ridge cones suitable?
 
Rigid cones tend to have breakup issues at high frequencies unless they are significantly damped, which usually will kill sensitivity. That said, one of the few full range drivers that ever appealed to me was the Zaph ZA14w08-5

http://www.madisoundspeakerstore.com/approx-5-woofers/zaph-audio-za14w08-5-aluminum-cone-mid/woofer/

While it doesn't have the dynamics that I look for, it does have the typical 10k peak to give some artificial high frequency articulation to make it seem like it extends further than it does. There are few songs it bothered me on, but on many, I didn't even notice the peak (probably due to the high q).
 
Has anyone used one of Audio Nirvana's full range drivers with the Eminence Alphas? How do the Audio Nirvanas compare to the Betsy drivers? Worth the additional money?

cubdog
 
i'm using audio nirvana super 8 cast frame on top of eminence alphas

they are more lively than the betsys, perhaps a touch brighter depending on the amp

i do prefer them to the betsys but the betsys are neutral and sound very nice
 
So many questions. I'm definitely going to try some OBs but will move slowly. I'm very ignorant when it comes to DIY and speaker design in general.

Assuming I use an Eminence 15in Alpha, can someone explain the basic difference between a folding baffle like the Betsy design, a plain flat baffle, or an H frame. I would prefer a flat baffle design from an aesthetic point of view but I don't understand what limitations there are to this approach. I do understand ever design decision is a compromise to some extent.

Thanks for the help.

cubdog
 
folding wings are used when you are trying to maximize your baffle area and (i think) prevent the back wave from cancelling the front. ie, it is a strategy to maximize your LF; not needed when you use a bass assist like the eminence alpha

poultry and others can weigh in re H-frame vs. flat baffle for the woofer
 
Earlier in the thread I posted a link to MJK's comparison (and you likely won't find a more comprehensive comparison) of the Alpha's performance in a flat baffle, h-frame and u-frame.
 
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