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1st Open Baffles; Need help!

gaslover said:
Dumptruck- what rolloff? I get response up to 25K. Best top end I've ever had.
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The one at the other end, of course, but then you've already said you're using it to only 500Hz, which is around where'd you'd get dipole cancellation rolloff for a baffle-less 8". One comment, though: middle C is around 260Hz, so you're using those 2x12" for a lot more than what I'd call "bass".
 
Agreed, but I don't hear anything negatory from that. A typical 12 driver can accurately reproduce 500Hz and above. A BIG plus is that my amp for the full-rangers never has to put out more than 2wpc because there is no bass demand on it. This means I am deep into class A territory with the amp. The difference is stunning (A vs. AB).
 
So I read the Lampizator site and said, "Hey, I've got those speakers!". I also had a conference table from my old office that I had to cut in half to get it out when we moved.
I was originally going to use the table to store the drivers in an upright position but when I cut the first hole I said"Open baffle!".
They have no calculation or thought behind them and yet they have major bass and the open sound that OB's are known for.
There's two 421's reconed as 416's a 16" 420 and a 811/802 horn per side. The table halves are 48 x 60 with curved tapered sides.
 

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I would suggest reading Martin King's OB theory and following his projects at the Quarterwave website. He's quite the OB guru and I've had great success building his designs.
 
maybe, since i am still at the cardboard stage, i should try adding an active sub to my setup just to see if/how much better it would sound.

without going out and buying a crossover unit, i guess i would use rca splitters to run the preamp signal to both my set amp (for the full range speaker on the open baffle) and to another amp (to provide output to the active sub). then i would use the frequency cutoff adjust on the sub to try out different levels.

crude but might give me the idea... how does that sound?
 
Martin,

As you know I really love my H-frames which have been the one constant since I discovered them on your site a few years ago. Have you found any other affordable woofers that you prefer over the Alphas or GW's?
 
That's really a question for a new thread or a PM. Let's try to keep this one on topic for the tennis guy.
 
RayW said:
That's really a question for a new thread or a PM. Let's try to keep this one on topic for the tennis guy.
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Ray, the topic is "1st Open Baffle; need help!"

The recommendation for bass augmentation has already been made. So what's off topic about a recommendations for a specific woofer?
 
After living with the Betsy's in the Wild Burro folding wings which were somewhat bass shy I switched to these. I patterned them after Martin's 07 flat baffle design. I run the Betsy's straight off a SET amp and use a solid state amp with a low pass on the Eminence Alpha 15A's.

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Poultrygeist said:
Have you found any other affordable woofers that you prefer over the Alphas or GW's?
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I have used the Alpha 15A in a couple of different OB designs and they have done the job. I also still have the Goldwood GW-1858 in the H frame I built a few years ago which is probably my favorite low cost design.

Those are the two affordable OB friendly (high enough Qts to not need EQ) woofers I have direct experience with, both work very well actively crossed over (sometimes passively depending on the full range driver efficiency) at about 200 Hz to many different full range drivers (Lowther - Fostex - Alpair - Jordan - Fountek) covering a wide price range.

On paper, meaning no direct experience, a few of the really low cost Goldwood 15" woofers appear to be excellent candidates for dipole systems. They are not so efficient which means using two per side (unfortunately more expensive but still a bargain) or a significant amount of low frequency boost.

Right now I am listening to expensive dipole drivers, four AE Dipole 15 woofers in H frames that are almost U frames (baffle shifted forward almost to the front of the box). These are paired with Lowther PM2C full range drivers. The bass goes deeper then my two low cost woofers and the Dipole 15 definitely can take more power without struggling. They are a step up from the Eminence and Goldwood woofers but not so large a step that I could not still enjoy or recommend the lower cost alternatives.

Martin
 
With bi-amping the 2 ways you're really not complicating the signal path.

The Betsy's in the folding wings vs the Betsy's on flat baffles with Alphas is like night and day.

The Qts of those 15" is not high enough for good OB bass.
 
i'm hoping to set up the baffle to switch in and out different drivers, like in the MJK design. thus, his use of a crossover setup would make the most sense so you could adjust the mix between the FR driver and the alpha. so you add the crossover to your path. and many of the pro crossovers are XLR so you need XLR adapters. seems to get complicated fast. am i making this too hard?

if like you i would use a SET amp for the FR driver and another amp for the alpha then you have inputs > preamp > crossover > 2 amps (SET and SS) > OB

or could i have inputs > preamp > y-splitter > 2 amps > OB, where 1 of the amps is a plate amp (like you use) which has an adjustable cut-off?
 
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