I would like a few more critiques of my design. - diyAudio
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Old 2nd January 2016, 07:08 PM   #1
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Default I would like a few more critiques of my design.

18 inch square sub.
250 watt plate amp with phase, cross point and amount. At eight ohm.
One downfiring vestigial 12 inch. stiff surround heavy coned pro woofer. NONpowered. Two 12 inch kappa nine infinity woofers. Powered. The two powered woofs, act in boxer fashion. So, their displacement during excursion, is compensated by the nonpowered downfiring woof. This I'm sure raises efficiency. And maybe lowest point. This nonpowered woof, is not weighted. It's downfiring, means that its dispersion, is in the same direction as the front and rear firing powered woofs. But in a 360 degree pattern. This excites walls less. Goes real low, and doesn't seem to need any dsp type comp.

What particular behavior should we expect from this config? Will it's 360 downfiring dispersion make the bass less localized? Easy excursion boxer type firing woofs, are they low distortion in this config? Will the bass be LESS tight? Is that a tube sound?

To my ears, I can boost it without rattling walls. It has no hump at inopportune passive resonance point. And, the powered woofs, were designed to have rising output at fs. Which is 29. They are six ohm, so three total.
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Old 2nd January 2016, 10:07 PM   #2
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Cmon. Did I invent a way to use a tiny vessel? Get big excursion with less power? Port without breathing? Get a 29hz boost? Does my passive radiator act on it's own harmonic volition? Or in direct displacement of my driven woofers? If in direct displacement, wouldn't that be as the driven ones where their excursion is concerned? Meaning, isn't it max excursion at 29hz? Being a slave to the far greater area driven woofers? What of bipolar woofer, with 360 dispersion bottom firing? The usual caution about passive radiators is:


Must have greater area than driven ones.
Must be weighted, which rules absolutely out, bottom firing passive radiator.
This being, I presume, to keep it in phase with driven ones. Or rather, to excite it selectively, at the missing area hz. Which makes sense, as the passive is SUPPOSED to be larger by half to whole. My superdriving my passive throwing convention on it's head. Superdriving supposed to be bad as you reach max excursion way too soon. My PRO woofer passive, being stiff surround, heavy cone, doesn't seem to reach max excursion any sooner than the driven ones.

Mains roll off on bottom. eight inch three way. So, a rather low sub cross.
Even stranger, phase twiddling doesn't seem to have much effect.

This is the most unobtrusive fastest sub I have ever heard. That you feel.
I cannot have gotten that LUCKY. There MUST be something to my madness.

Which is crucial, as I am about to recommision my mini utopia's. As mains. And utopia drivers are FAST.

Last edited by Highfido; 2nd January 2016 at 10:14 PM.
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Old 2nd January 2016, 11:05 PM   #3
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Mini
Utopias without ports, and flat baffle. Which theoretically should cross better to sub.
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Old 2nd January 2016, 11:09 PM   #4
DUG is offline DUG  Canada
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Some pictures might be nice.

Driver p/n or specs?

Response plots?
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Old 2nd January 2016, 11:13 PM   #5
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What do you mean by Boxer? What is the sub made of?

Typically a PR of greater area is required. ie a 15" PR would be used with a single 12". Weigh is used to tune it (it is a port).

dave
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Old 2nd January 2016, 11:44 PM   #6
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Boxer, as in BMW motorcycle or Subaru engines. Pistons go away and towards. Bipolar. In theory, this keeps resonances in sub, and walls minimized. BUT, USUALLY, the sub is sealed, thus, the woofs are heavy damped. Or worse, ported. In my design, the passive radiator eases the fight between the driven woofs. And I stuffed the port, so, it is a leaky seal. This could be used to tune the passive to not over excurse. SP?

Yes, my design is far from any that I have seen. Being that it is supposed to SUCK. It truly is the best that I have ever heard. Slam at low volumes. Allowing to turn up volume and not disturb others.

The passive is a nondriven pyle pro12. The driven pair are Kappa 9 infinity 12 woofs. They are semi open baffle spec woofs. And FS is 29. Fed with 250 at 8ohms. Likely 325ish at 4 ohm. The shell is a repurposed realistic sub. With vibration damper stilts. Passive is recessed. The gap at bottom of sub cab is 1/4 inch. So, the radiation pattern is, bipolar front and rear fire, with a bottom firing passive radiator. Handing off to now three ways, soon mini utopias.

Passive elec components could tune resistance of passive, as it makes juice from being excited by driven woofs.

Last edited by Highfido; 3rd January 2016 at 12:04 AM.
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Old 3rd January 2016, 12:39 AM   #7
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Quote:
Originally Posted by Highfido View Post
Boxer, as in BMW motorcycle or Subaru engines.
This is what i thot, but needed to check. Push-push is the commonly used parlance. I have stereo push-push subs with SDX10. We built them of well braced 15mm baltic birch to verify how much push-push reduces the box load. I had to turn off the sats and crank things up to 10-12 dB above loud to get the tops of the boxes to move (no problems on the sides).

Quote:
BUT, USUALLY, the sub is sealed, thus, the woofs are heavy damped. Or worse, ported. In my design, the passive radiator eases the fight between the driven woofs.
With push-push the kind of cabinet makes no difference. A PR system is just using the PR as a port (in cases where the port needs to be so large as to be impractical). There is the extra mechanical resonance of the PR todeal with thou.

And I stuffed the port, so, it is a leaky seal. This could be used to tune the passive to not over excurse. SP?

Quote:
The passive is a nondriven pyle pro12. The driven pair are Kappa 9 infinity 12 woofs. They are semi open baffle spec woofs.
What do you mean by sem-OB? The 1st thot that comes to mind is WAY too much bass (which some people like)

Quote:
So, the radiation pattern is, bipolar front and rear fire, with a bottom firing passive radiator.
At these low frequencies even a single driver is omni-directional.

dave
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Old 3rd January 2016, 12:50 AM   #8
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You are making me feel not so stupid. The AMOUNT of bass is absolutely adjustable. Not at all boomy. Normally, a box that small would be a boom grenade, and tuned far too high.

It flouts all passive rad wisdom. And yes. I did think that the passive would in effect be a port that didn't breathe.

One of the pluses is, it is good apartment sub. Good new house construction sub. Good must hide sub.

Now I have to add remote to the level and cross point knobs.

Last edited by Highfido; 3rd January 2016 at 12:53 AM.
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Old 3rd January 2016, 05:56 PM   #9
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Okay, so you're planning on using two similar drivers, and one dissimilar driver. The two similar drivers are long-throw sub drivers, and will play the range of low frequencies.

The non-driven driver will be a PA driver, with suspension that will go nonlinear quickly. You'll need a lot of weight to tune it like you would a passive radiator, but I don't think that's exactly what you're planning to do with it.

What are you planning on doing with that Pyle driver?

Chris
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Old 3rd January 2016, 08:17 PM   #10
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The pyle is to alleviate the pneumatic damping of the driven woofs. My interest was if the passive, since it is shoved by twice the area, would not act like a passive rad. Without the weight to make it shun higher hz action. I am hoping that the pyle will go as low as the driven ones. Since it is more pneumatic shove, rather than harmonic excitation.

I have proven that it is SOMEWHAT true. As it goes low and has no peaky behavior. It might test less than perfect. But, the response is so transparent, and doesn't interfere with other hz, that I would have a hard time going conventional.

The actions of the driven woofs, would discourage harmonic based flailing, as that would cause the driven woofs to act against their electrical urging.

My flouting of passive rules, should be of interest. Particularly as it doesn't exhibit any expected shortcomings.

I BELIEVE the efficiency of the not dissuaded excursion of driven woofs, and the overall area conewise, allows lesser volume to suffice. Which lowers harmonic distortions. Not as impressive to nubes though. Cone movement being the indicator of quality and performance.
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