Jump to content
Second Skin Audio

6th Order Port Area Experiment


Recommended Posts

  • Replies 46
  • Created
  • Last Reply

Hell yea, glad I found this thread

2007 Chevy Tahoe (SOLD)

12 ~ FI Audio X series 10" w/BP option

2 ~ DC Audio 5.0K @0.67

3 ~ DC Audio 5.0K @1.0 

2 ~ PPI 3 way sets (not installed yet)

1 ~ RF T400-4, 1 ~ RF T600-2, 1 ~ RF T600-4

4 ~ CT Sounds 5.25" Strato comps  (rear fill only)

1 ~ XS Power D4800

1 ~ XS Power D3400

8 ~ XS Power XP3000

160 stock alt, Mechman 370 Elite, 185 DC Power

320+ Sq. Ft. Sound Deadener

Pioneer AVH-X5500BHS

Youtube: https://www.youtube.com/user/knfjdkghjudfhsgkjdhf/videos?sort=dd&view=0&shelf_id=0

Link to comment
Share on other sites

After you test the 32hz rear port then bring it down to the mid to high 20's where people realistically tune rear ports for 6th's. 

Smaller rear port is better. Tested it in many different cases myself multiple times. Any data is good data though. :)

1996 GMC Sonoma
Four Fi BTL Neo 18's In 2:1 6th Order Bandpass
2 Ampere 5k's @ .5

TEAM FI
TEAM #LITHIUMCANTDEMO

 

On 10/20/2013 at 0:37 AM, KillaCam said:

Fucking with a Prius driver is like making fun of a disabled kid. Pussies.

Link to comment
Share on other sites

28 minutes ago, Raptorman said:

After you test the 32hz rear port then bring it down to the mid to high 20's where people realistically tune rear ports for 6th's. 

Smaller rear port is better. Tested it in many different cases myself multiple times. Any data is good data though. :)

I can do that.  

I'm glad you commented on what I going to do, I was hoping you would give your input.

"Nothing prevents people from knowing the truth more than the belief they already know it."
"Making bass is easy, making music is the hard part."

Builds:

U7qkMTL.jpg  LgPgE9w.jpg  Od2G3u1.jpg  xMyLoO1.jpg  9pAlXUK.jpg

Link to comment
Share on other sites

Tuned in.

91 C350 Centurion conversion ( Four Door One Ton Bronco)

250A Alternator (Second Alternator Coming Soon)

G65 AGM Up Front  / Two G31 AGM in Back

Pioneer 80PRS

CT Sounds AT125.2 / CT Sounds 6.5 Strato Pro component Front Stage

CT Sounds AT125.2 / Lanzar Pro 8" coax w/compression horn tweeter Rear Fill

FSD 5000D 1/2 ohm (SoundQubed 7k Coming Soon)

Two HDS315 Four Qubes Each 34hz (Two HDC3.118 and New Box Coming Soon)

Link to comment
Share on other sites

I've been chipping away at this project a little bit each day.  I've started my harvest season so I don't have much spare time, but I want to keep working on this experiment as I'm able to. 

I finished construction of the enclosure and two of the port configurations.  I still need to do the lower-tuned port configurations.  I was able to take some impedance measurements of the 6 sq in and 25 sq in port configurations.  Here is the test setup:

5986ad1d45072_2017-08-0322_14_11.jpg.62c198f18f71be67ba8fca1b97f267c1.jpg

 

I took impedance measurements between 20-100 Hz at three different input power levels (2, 21, & 38 volts).  

Here is the results of the large rear port (25 sq in) configuration:

LP.PNG.a9042ccdb24051fceb1a23c52943beb0.PNG

 

Here is the small rear port (6 sq in) configuration:

SP.PNG.3b135848e141cb46dbed610eda3eb466.PNG

 

And here it with the rear port plugged to make it into a 4th order bandpass:

FO.PNG.f68f48299b6dad6b987756cd019f0821.PNG

 

I have a theory as to whats going on with the different port sizes, but I'm going to wait until I get all the testing done before I give my interpretation of the results.  I'm curious to hear what you folks think is going on based on the impedance measurements.

After I get the final two port configurations built and impedance tested I will be doing SPL testing.  To do it right I need to do the SPL testing outdoors.  By the time I set everything up, do the testing, and then put everything away it turns into a several hour project.  I probably won't have time to do that for several weeks, but I'll get it done eventually.  

"Nothing prevents people from knowing the truth more than the belief they already know it."
"Making bass is easy, making music is the hard part."

Builds:

U7qkMTL.jpg  LgPgE9w.jpg  Od2G3u1.jpg  xMyLoO1.jpg  9pAlXUK.jpg

Link to comment
Share on other sites

Im with 8, sort of.  haha  Im guessing too much port area to play below tuning frequency effectively?  

Maybe the impedance rise caused by a speaker unloading below tuning is more influential to the circuit than impedance rise caused by choking a small port (high velocity=high drag).  They both cause rise, but maybe one is more effective at making rise than the other.  ? :shrug:

But it seems that near the tuning frequency, the large port prevents impedance rise.

Looking forward to more data!  Cool stuff man

Chevy Sonic Wall (4) 15's on 10k Build Log

https://www.stevemeadedesigns.com/board/topic/209412-2015-chevy-sonicwall4-15s10klithiumlarge-case-hairpin-us-alts/

(4) Fi SP4 15's | (2) Ampere 5Ks | Active! | Arc KS600.2 & KS125.2mini | CDT Silk Domes | Silver Flute 8s | 240Ah JY | US Alts

Jeep Wrangler JK (4) 8's in a 4th Order Build Log

https://www.stevemeadedesigns.com/board/topic/209841-shadow-2016-jeep-wrangler-jk4th-order4-8sdc-35klarge-case-hairpin-us-alts/

IG @walledsonic

Link to comment
Share on other sites

thanks for the update.
Since I am currently building a 6th. I'm really curious to see how this comes out

Link to comment
Share on other sites

Archived

This topic is now archived and is closed to further replies.

  • Recently Browsing   0 members

    • No registered users viewing this page.
  • Who's Online   0 Members, 0 Anonymous, 195 Guests (See full list)

    • There are no registered users currently online



×
×
  • Create New...