Reverse Engineering (Enclosure)

[5t4y_50L0]

To help me better understanding box building I tried to input my box design I purchased but the design input doesn't match my designer's specs.

slot port length is exact but the app(s) say 33 Hz, I was told my box is tuned to 40 Hz.

I was also told I have 1.4 air space but the app(a) again say 2.04 net volume

Winisd, bass box pro 6 and car audio app

Click to read more...

 

[James Bang 5,000+ posts]

When measuring net volume, make sure you don't count the port volume or the speaker's displacement.

 

[chillin 10+ year member]

What's the measurements of your box? Did you factor in the thickness of the wood when doing your calculations?

 

[5t4y_50L0]

Sorry, I spaced this and forgot where I posted this.

29w x 11.5 H x 19D
Slot port front fire L-shape 13 from baffle (14.5 with baffle) and 12 at the turn
3/4 MDF

I was told 1.4 air space and tuned close to 40 Hz

 

[5t4y_50L0]

Sub displacement 0.088 x 2

5, 45 angles including port

 

[1aespinoza Premium Member]

5, 45 angles including port

I read that 45 degree angles change the box tuning. I think it has to do with the air moving faster. So it would make sense that you are getting 2 different outcomes.

 

[shredder1 10+ year member]

I read that 45 degree angles change the box tuning. I think it has to do with the air moving faster. So it would make sense that you are getting 2 different outcomes.

They can change tuning but only by shortening the effective length of the port and/or displacing volume in the enclosure if not accounted for.

A port with a high ratio may also affect tuning in some instances but I've never heard of airflow changing tuning.

 

[shredder1 10+ year member]

Sorry, I spaced this and forgot where I posted this.

29w x 11.5 H x 19D
Slot port front fire L-shape 13 from baffle (14.5 with baffle) and 12 at the turn
3/4 MDF

I was told 1.4 air space and tuned close to 40 Hz

Sub displacement 0.088 x 2

5, 45 angles including port

Double baffled?
Width of slot port? I'm assuming it's 10"h x w?
Total internal length of portwalls are 25"?
Were the 45's part of the design or something you added in?

 

[5t4y_50L0]

Double baffle,
port 3x10, (1) 13" is connected to the double baffle and the turn (2) 12"
45s were optional and was told I could add them

 

[shredder1 10+ year member]

Sorry, I spaced this and forgot where I posted this.

29w x 11.5 H x 19D
Slot port front fire L-shape 13 from baffle (14.5 with baffle) and 12 at the turn
3/4 MDF

I was told 1.4 air space and tuned close to 40 Hz

Sub displacement 0.088 x 2

5, 45 angles including port

Double baffle,
port 3x10, (1) 13" is connected to the double baffle and the turn (2) 12"
45s were optional and was told I could add them

Not exactly an accurate autopsy on your enclosure here but with the info supplied so far quick and dirty I get about 1.9ft3 net 30in2 of port tuned mid 30's.
I couldn't factor in the port 45 as it will most likely lengthen the physical port length if done right. That in turn would decrease net airspace raising tuning fractionally even more.

Best guess is best I got without the actual enclosure in hand or design to reference.

 

[5t4y_50L0]

Ok, I hear what you're saying, I originally didn't want to 45 the port but as I was about to place the top on, a friend said to do it to make the port 3" true all the way through.

Designer told me 1.4 airspace, tuned close to 40 Hz. I originally wanted 33 Hz but he said with my limited space 33 Hz can not be achievable. I paid and built it. After struggling with the tuning I decided to reverse engineer, the box hits hard and sounds good on certain songs, like three six mafia - sippin on sizzrp, sounds so good but then my lady plays Jessie murph - wild ones and the lowest note flutters ..

Anyway my initial homework says
29w x 19d x 11.5h
3x10 port
gross 2.78
net vol 2.12
Port 33 Hz

Some of these apps build the box different than how mine was constructed, like my side goes front to back and sits inside top and bottom, the online 3d mock ups have the sides sit inside front, back, top and bottom. Some even have the baffle, opposite end of the front fire port over the side. My side wall overlays onto the baffle

 

[shredder1 10+ year member]

100% the port as designed to the baffle matters, and keeping the port as close to the port area throughout matters (efficiency). I'm willing to bet you ended up with a mid 30s tune. Accurate tuning blows people's minds as usually extension suffers by overcompensating for perceived output in the band and peakiness is overlooked. The resulting response produced combined with cabin gain peaks viciously around tuning. Smallish airspace tuned accurately with cabin size in mind will often play lower than a lower tuned oversized enclosure.

35hz done right can dig pretty deep, imagine a capable sub on big power tuned low...

...Madness...

 

[5t4y_50L0]

Thanks for the feedback, before I took the enclosure out of the vehicle I lined the internal walls with pollyfill and inverted the subs. Only then did I get the response I craved.