Burp box...

[shredder1 10+ year member]

I said recently that I would NOT do this...but... LOL!.. Today I took stock of all the materials I have laying around so I tried to come up with something that I could throw in the Blazer and MIGHT hit a good # for the next bassmeet... I was told to tune around 42-44 hz with some port area... without trying to ask for advice I sat down and used the 4 e@ 37.5" x 16" x .75 MDF pieces I had on hand and tried to come up with something that will yield about 4 ft3 net and tune to 42-44... I came up with a 3.8 ft3 which I'll invert the subs to net around 4.1 ft3... the limitation is my thinking of course and materials... I'm trying to minimize cuts and use what I have on hand... space in the vehicle is not an issue... I'll just swap subs from the current box then plop it in on top of the box or on top or the backseat... LOL!... this is what I came up with...

and since the subs will be inverted I added about .3 ft3 when I modeled it... and modeled it at 4.1 ft3 with the same port...

As you can see I made some compromises when figuring port area to stay near 4 ft3 net... It looks like I'll start to see compression at 2200 watts... The material on hand limited me a lot so I did the best I could... and modeling in Winisd is new to me... this compression will affect me how?.. should I just go for it?...

Opinions welcomed as this Winisd is new to me... thanks in advance...

Does it look like the layout will be a problem?

Advice.. Opinions?

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[hispls 5,000+ posts]

Do not add the 90 degree coming off the inside port wall. Port length will be long enough due to loading along that wall.

 

[shredder1 10+ year member]

Do not add the 90 degree coming off the inside port wall. Port length will be long enough due to loading along that wall.

It looks like if I do that it'll change tuning to 47 hz... I was told that 42-44 hz is the best bet and the same guy predicted what I would hit yesterday and what frequency I'd be loudest at... exactly... It was scary accurate... LOL!.. are all the 45's necessary/helpful?.. or only in certain corners...

Do I want to play with tuning?... or stick with 43 hz?... The pieces are all cut and beveled...

 

[Boomin_tahoe 5,000+ posts]

Disagree on the backseat idea.

 

[shredder1 10+ year member]

Disagree on the backseat idea.

Then I'll just put it on top of the current box about 6-7" from the tailgate...

 

[Boomin_tahoe 5,000+ posts]

A burp box for.....daily or bassmeets? I would put it in place of your current sub enclosure, for better/best results.

 

[shredder1 10+ year member]

A burp box for.....daily or bassmeets? I would put it in place of your current sub enclosure, for better/best results.

Just as a different box I could use only for bassmeets... maybe do a higher number... I'm stuck at 146.4 as the cabin peaks at 35 hz with my current box... LOL!..

 

[hispls 5,000+ posts]

It looks like if I do that it'll change tuning to 47 hz... I was told that 42-44 hz is the best bet and the same guy predicted what I would hit yesterday and what frequency I'd be loudest at... exactly... It was scary accurate... LOL!.. are all the 45's necessary/helpful?.. or only in certain corners...

Do I want to play with tuning?... or stick with 43 hz?... The pieces are all cut and beveled...

The port will load along that back wall. It will act longer than it looks. If I'm wrong it'll be super easy to glue that piece in later, but if I'm right you will have a bear of a time cutting that port shorter.

Keep the 45 on the corner with the port, I don't see any value in putting them elsewhere.

 

[shredder1 10+ year member]

The port will load along that back wall. It will act longer than it looks. If I'm wrong it'll be super easy to glue that piece in later, but if I'm right you will have a bear of a time cutting that port shorter.
Keep the 45 on the corner with the port, I don't see any value in putting them elsewhere.

You're saying that the subs will "see" a longer port?... How can that be modeled?... port center is 13.25" plus 2.125" to exit into the box?.. Did I do that right?... or is it something I'll pick up with time?

 

[kr15 5,000+ posts]

If you wanna meter legal... subs up, port to driver side. 20^2 and tune about 46.

Since you already started on the baffle, sub and port back... for legal metering if you tune around 45, you will should peak 51 sealed and 49 outlaw. Also wanna run alot of port this way.

These are full fledged burp boxes tho. They will not sound good. They will basically play 47-55hz loud

 

[kr15 5,000+ posts]

My mistake, looked at baffle again.

Subs up and port back. I had good success in 4.1cu at about 42 for a box that could do both sealed and outlaw #s

 

[kr15 5,000+ posts]

 

[shredder1 10+ year member]

If you wanna meter legal... subs up, port to driver side. 20^2 and tune about 46.
Since you already started on the baffle, sub and port back... for legal metering if you tune around 45, you will should peak 51 sealed and 49 outlaw. Also wanna run alot of port this way.

These are full fledged burp boxes tho. They will not sound good. They will basically play 47-55hz loud

Okay... then I'll lose the 2 1/2" piece on the end of the port that'll raise the tuning... leave the 45 behind the port and lose all the other 45's... Oh yeah... I'll have my SSF at 35-37 for sure... It'll be almost a one note wonder... LOL!... also.. if you read the start of the thread I was wondering how bad the compression will affect volume wide open... IDK how much power I have on tap but I'm worried that this might be a factor... or am I worried about nothing?... just open it up and see what happens for 10 seconds?

 

[shredder1 10+ year member]

My mistake, looked at baffle again.
Subs up and port back. I had good success in 4.1cu at about 42 for a box that could do both sealed and outlaw #s

Yes I'll be subs up port back... will 66 in2 of port be a problem... I really don't know how much power I've got... I tried to compromise the best I could...

 

[kr15 5,000+ posts]

This might be frowned upon... but i dont pay attention to any of that. I never use winisd. I dont feel its practical for spl, where literally nothing makes sense... i build, test, rebuild, retest etc.