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Markous

Passive Radiators or External Ports?

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HAHAh good to see PR's of interest elsewhere!  Youve got the pr thing correct though, build as if you were going ported. this http://www.mh-audio.nl/PassiveRadiat"or.asp is a great online calc that will help. BUTT! the final weight this calc tells you to add also includes the weight of the cone of the passive radiator itself.

Say it says you need 1000g of mass, but your 2 15" PR's are 300g each. 1000-600 = 400g added mass / the 2 PRs = 200g on each pr. 

email psi and theyll let you know

 

As far as mounting, i dig the bolt frankenstein look, and it would be a hell of a lot easier to play with a few more grams here and there to fine tune. 

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Right now i have a 15hz PFM chip in my Matrix+ and the subsonic on the 2k all the way down.

Will i need to adjust this with a PR setup?

Thinking of tuning in the 30hz region like Steve did with his towers, wondering if i should eventually order a 25hz chip from AC?

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Earthquake Pump-12 eh?   I like the idea.

Quote

Earthquake PUMP-12 is essentially two horn loaded 12-inch passive radiators in a single unit. With many different applications and uses, the PUMP-12 is designed to add up to +6dB of bass without any need of additional input power (when installed in a sealed enclosure).

Bit of a bold claim no?

 

 

 

 

 

 

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Another question i just thought of that i'd like to ask.

Could each PR be tuned to a different frequency?

Also wondering if i need to use a subsonic filter as i asked above.

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No, you shouldnt tune to different frequencies unless you were doing a sixth order with 2 separate chambers.

You will need to set your SSF.  Otherwise, at some point below tuning, you could launch a sub or PR.  Depends on power though.  I ran 7kW worth of subs on a Sundown 1500 and didnt need to set the SSF since there wasnt enough power to reach Xmax.

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It was just a thought, i was curious if a person could have a 6th order type output by tuning each differently in a common chamber.

Would the SSF need to be set 1/2 an octave below the PR tuning like a ported enclosure?

@meade916didn't mention anything about a SSF when he did the shop towers did he? (that's my main inspiration for all of this) gonna have to go back and re-watch those video's.

I am running my sub with a matched rms rated amp but am only clamping  about 60% of the rated power if the termlab metering i recently had done is correct.

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1/2 octave is commonly used as a starting point.  My box is tuned to 26 Hz and if I tune at half octave (19.5Hz), I would far pass Xmax in my setup under full power, so mine is set at 23Hz with my current subs.  This is my experience with my equipment. 

I would play around with the system and determine the best frequency for the SSF once you have it playing.

 

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Yeah i think i'll be best off if i drop some cash and grab a IM-SG for tinkering with the setup.

Nick from SI told me he would forward the T/S numbers of my sub to David at PSI to get me hooked up proper when i'm ready.

My sub is apparently built differently than the re-introduced HST-15's they have on their website now.

Edited by Markous

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Was looking for this pic and the thread just popped up.  Triticum posted about a gauge ("wedge micrometer") you can make to check your Xmax easily:

 

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So i think this idea might be dead 😟 with some email exchanges with Nick at SI he recommended not using the PR's as they'd need ALOT of weight.

He also confused me a bit, at first telling me my 4ft sealed box was ok in a HST-15 thread topic on DIYMA, then recommending in later email exchanges that i go with the 1.2 cubes sealed as the ones on the SI site are recommended to have.

Either way i'm gonna get the IM/SG when they come back into stock in April (AFAIK) and get the T/S #'s from my sub and go from there.

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