Jump to content
SpeakerBoy

Passive Radiator tuning calculation

Recommended Posts

I'm having trouble getting the right mass to tune a PR enclosure

 I got ~1200 grams when I used a calculator online but 158 grams when I used the mass of the air in the port as my starting point. I feel like i'm missing something.

i'm aiming for 8cu @ 26hz with a single 18" and two 18" PR's

What do I need to do to get the correct calculation? The reading seems straightforward but I keep getting these two opposing answers. 

 

Thanks, 

          -Chris

 

Share this post


Link to post
Share on other sites

Perhaps you should share what you are using.  Obviously something is drastically wrong...

Share this post


Link to post
Share on other sites

(2) PSI 18" PR's and my BTL18. As soon as I figure out how to calculate the tuning I'm ordering the PR's. I figure I can just add mass til it sounds right but I kinda wanna know what's going on.

 

WinISD says 650g (not sure if that's each or total) and has a curve I think fits what I'm looking for, don't know how to factor in cabin gain in relation to the graph but it slopes down til about 35 then rises back up til 26hz where it begins to drop off. Mid 20's is what I want to emphasize with less pronounced upper 30's-40's. I just want some trunk back, not to mention it looks sexy.

I can upload the winisd plot if it means anything.

 

I've heard rumors Fi makes PR's? Only going with the PSI's because they were easy to find, not too expensive, and I can get blank dustcaps. They seem beefy enough for this build.

Edited by SpeakerBoy

Share this post


Link to post
Share on other sites

Don't you have vance dickasons book?  I remember you buying it I thought.  Always best in a first design to calculate by hand.  

Share this post


Link to post
Share on other sites

No, that's definitely still on the list of things to buy.

Share this post


Link to post
Share on other sites

How much weight did you end up using on each of your pr's

Share this post


Link to post
Share on other sites
On 3/8/2017 at 7:55 PM, Ernestgary said:

How much weight did you end up using on each of your pr's

Sorry, missed this in the recents list. 

I honestly don't know for sure, I never measured it. It ended up using a two or two and a half inch long 3/8" bolt and about eight or ten 3/8" washers. 

It doesn't really matter because I just added weight until I achieved the desired tuning. 

IMG_0027.JPG

Share this post


Link to post
Share on other sites
5 hours ago, altoncustomtech said:

It doesn't really matter because I just added weight until I achieved the desired tuning. 

...which is your end goal :)

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

  • Recently Browsing   0 members

    No registered users viewing this page.

    1. Recent Topics

        • 6 comments
        • 59 views
        • 2 comments
        • 34 views
        • 2 comments
        • 50 views
        • 154 comments
        • 10,806 views
        • 19 comments
        • 222 views
        • 7 comments
        • 328 views
  • Similar Content

    • By slim142
      Not sure how many people here know what these are used for or what they are, but I thought I would still post it just in case anybody sees anything they might be interested on.
       
      These are from a project that I had to cancel because I started college a few years ago and money became insufficient to finish it up.

      All prices include shipping CONUS. Paypal only please. No international shipping.

      Let me know if you have any question. I also take offers if you buy more than one item.
       
      heatware: slim142
      eBay ID: presler142
       
      TFC Xchanger 480 Quad Radiator NIB - $95
       

       

       

       
      TFC 120mm Fan Shrouds NIB - $60 for all 4 (each includes red, blue & green LEDS!)
       


      Pentek In-Line Water Filter NIB - $20
       


      Laing D5 Vario/Swiftech MCP655 Inline 12V DC Pump (with variable speed knob) + Detroit Thermo D5 Top + Bitspower 655 Mod Kit - $110 (all together)
       


      EK Reservoir RES250 Rev. 2 Multi-Opton Reservoir + Anti-Cyclone + Case Holders - $45 (all together)
       


      Alphacool Valve + 2 Bitspower Extension fittings + Bitspower Cover fitting + Bitspower Multi-way (3-way) fitting + Syringe + Silver KillCoils by iandh - $25 (all together)
       

       

       


      Sunbeam PSU Modding Tool Kit + Some black heat shrink and cable sleeving + 4 120mm Black Fan Grills + 1 120mm Silver Fan Grill + 3 140mm Silver Fan Grills - $15
       

       

       


      Swiftech Steel MCB-120 Radbox Rev. 1 Black - $15
       


      HP Expresscard Analog TV Tuner Card - $15
       


      Two D-Tek GFX UNI-Sink (8800Gt/GTS G92) - $25 (for both)
       


      Two D-Tek FuZion GFX 2 GPU Water Blocks - $50 (for both)
       


      Bitspower BlackFreezer Striker II Extreme 790i Chipset Water Block - $45
       

       

       
       
      Here is my Woot! screaming monkeys collection. Well taken care of, they have never been played with, thrown/fly/scream.
       
      Get the 3 giant monkeys (still in their plastic bags) for $50
      or any 5 regular for $20
      or get all 24 of them for $90
       

       

       

    • By Omega_Ace
      If you have two boxes at the same volume and say one had a 2" slot port width and the other had a 3.5" port width tuned to the same frequency would there be a difference? Would the 3.5" port allow you to feel the lows better than the 2" port but sound the same since they are tuned the same?
    • By bassthrashin
      I would like some input on building an enclosure for 2 ZCON 15D2's. The max cubes available for the box is 7(3.5 per sub) after displacements. I want to tune at 31hz. I have seen the recommendations SSA's site for enclosures but would like to have some outside information on how well these will do in 7 cubes . They will be running off a SAZ3500 at .5ohms. Thanks.
    • By 10rogerd
      Hello all, I'm new to this forum, but not to car audio. I am however new to the Sundown woofers. I'm hoping you all can lend some help and thank you in advance on my enclosure design. What I have is an 05 Acura TL I'm doin a pair of Sundown SA12s in the trunk. Subs to be fired foward and a 6in Aero either out the back or side. I have tried several enclosures with foward fired subs & port, but the car just did not really like it. Last setup was a single CV Stroker12, power was supplied by an O.S. USamps VLX400 1ohm mono. I had good results with two 4in PVC ports fired back, Sub obviously foward. Then tried a 6in Aero out the drivers side of box. The Aero was slightly better. Anyway, my questions are... I have roughly 31in wide/26in deep and 13.5in tall to work with. I have an enclosure drawn up already with a net volume of 4.05 ft>3 and Torres is telling me with the 6in Aero @ 17in long this will yield me a tune of 29.64htz. Does this sound rite? I do want it to play very low!! I Only play music. Rap/Hip Hop/R&B/Funk/lil bit of rock/metal. My other concern is how will these subs like this size enclosure with the brutal power of the VLX? Amp is "rated" @ 2400 wrms @12.5v. Charging system is decent with a total of 4 large batteries and a 50farad Stinger Cap. All power/ground wire is 1/0 Monster Cable. Voltage playing it hard stays in the mid to high 13 volt range. Any input on if this will work fine would be great! Thanks again everyone.
  • Recent YouTube Posts

×