# 4th Order Build Opinions

the12volt
Joined: March 07, 2002
Location: Louisiana, United States
Posted: June 16, 2016 at 5:28 PM / IP Logged
Your build is looking nice, but don't put too much weight into the number of views. Search engine spiders account for most of those and there are many visitors that are not members that cannot reply.
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praisewaves
Member - Posts: 16
Joined: May 24, 2016
Location: Tennessee, United States
Posted: June 17, 2016 at 8:24 PM / IP Logged
Thanks for the encouragement.
Well I've done the math today and a lot has changed I originally planned for 52ft^3 12.5 sealed and 39.5 ported making it an 3:1 4th order with 4 15s, after a lot of change in plans, working with the shape of the car, deciding to make the battery/amp space bigger, and my final decision being to go with 3 18s rather than 4 15s after displacement I now have 33ft^3 9 sealed and 24 ported. a heavy 2.5:1 ratio
Cfrittswallace
praisewaves
Member - Posts: 16
Joined: May 24, 2016
Location: Tennessee, United States
Posted: June 19, 2016 at 12:46 AM / IP Logged
My original build schematics 4 15s
New corrected and final build schematics 3 18s
Cfrittswallace
praisewaves
Member - Posts: 16
Joined: May 24, 2016
Location: Tennessee, United States
Posted: June 20, 2016 at 11:15 AM / IP Logged
OK so I really need some help here, someone that knows there stuff please help. I run my box with three 1800 watt platform 2 psi 18s on WinISDbeta (first time use) and I know what Hz and dB's are obviously but not really how to read them on a graph yet so can someone please tell me if this is good or bad or if I need to udjust somthing or if you need different info or more detailed or whatever
Gain Chart:
-3dB = 28Hz & 87Hz
0dB = 30.5Hz & 79.5Hz
11.7dB(Peak) = 52.5-55Hz
Phase Plot:
350-50 deg = 33-76Hz
SPL:
149-149.6dB(Peak) = 45.5-58.5Hz
Cfrittswallace
haemphyst
Platinum - Posts: 5,054
Joined: January 19, 2003
Location: Michigan, Bouvet Island
Posted: June 21, 2016 at 5:12 PM / IP Logged
Well, I can certainly say it's dramatically more than I'd ever even attempt... I'm a small sealed enclosure kind of guy, with the brute force and influence (aka BFI) method of powering a system into the desired curve.
I'm not a fan of bandpass enclosures, generally speaking, and I'm more of a SQ guy (thus the distaste for bandpass) but I respect you greatly for the effort you're putting into this system. So far, it looks good, too! I'd love to chime in other than this, but I've never even attempted to build a bandpass system.
Keep it up!
It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice.﻿ You should write it down."
praisewaves
Member - Posts: 16
Joined: May 24, 2016
Location: Tennessee, United States
Posted: June 21, 2016 at 6:20 PM / IP Logged
Thanks for the support man, I won't lie I am really nervous because I've never don't one this big or done a bandpass either but im taking my time and I've done ALOT of research. The farther along I get the better I feel about it thou so I've got good expectations
Cfrittswallace
praisewaves
Member - Posts: 16
Joined: May 24, 2016
Location: Tennessee, United States
Posted: June 24, 2016 at 7:57 PM / IP Logged
got my port built today i decide on 20x26x7.75 making it tuned at 48.5Hz, i know i keep changing everything but id rather change my plan a thousand times and get it right at the end. plus im new to the big builds so im learning and correcting as i go
also i know the port is alittle premature considering i dont have my port wall yet but im pretty broke right know and this is what i could afford to do this week so its better than doing nothing
Cfrittswallace
praisewaves
Member - Posts: 16
Joined: May 24, 2016
Location: Tennessee, United States
Posted: June 24, 2016 at 8:09 PM / IP Logged
heres my gain chart from winISD i never could get help so i just tryed to tune it where it is as broad an even as possible, for a noob in the 4th order builds i think im doing pretty good im very confident in my buid =) as always keep viewing and ill post more as soon as possible
-3dB=27.79Hz&84.65Hz
0dB=30.33Hz&77.47Hz
11dB=45.54-51.07Hz
Cfrittswallace
praisewaves
Member - Posts: 16
Joined: May 24, 2016
Location: Tennessee, United States
Posted: July 04, 2016 at 8:17 PM / IP Logged
got the port wall in =)!!!! starting to close in and look more complete
Cfrittswallace
haemphyst
Platinum - Posts: 5,054
Joined: January 19, 2003
Location: Michigan, Bouvet Island
Posted: July 21, 2016 at 12:15 PM / IP Logged
Still looks really good! Like I said, more than I'd attempt, but you're doing a bang-up job!
It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice.﻿ You should write it down."
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