Burp box issues

[Zeroflex]

Hey guys and girls. I'm having an issue with a burp box I've just build. I have the plans given to me by a freind know has made a few diffrent style burp boxes but for some reason this is not hitting what I thought it would. My aim is 155's on 5k in a minivan/wagon setup.
My system is:
1 x ZeroFlex 5k
2 x ZeroFlex EVO 15's
3 x 100ah lithums
1 x 500farad cap bank

I've attached the spec my mate gave me and pix of the box, the port is 11" round x 13" long internal.
I am thinking of going 45's internal and changing the port to a horn style starting at 9 1/2" internal Caming out to a 11" external at 8" out side the box.

Currently only managing to get 149.8 at 46hz out of it sealed on dash which is way off where I'm aming for.
Cars resident frequency is 56hz.

Any help would be greatly appreciated thanks

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[THATpurpleKUSH 5,000+ posts]

What kind of vehicle are you using?

What is the resonant frequency of the vehicle?

What impedance is it rising to?


If you cant answer those questions then you need to take some measurements and do some tests and report back because that data is essential to getting louder.

2 15s on 5k should be an easy 150 but I doubt a 155 unless its in a CRX.

 

[MattinMO]

Holy huge short port

 

[Louisiana_CRX 5,000+ posts]

Hey guys and girls. I'm having an issue with a burp box I've just build. I have the plans given to me by a freind know has made a few diffrent style burp boxes but for some reason this is not hitting what I thought it would. My aim is 155's on 5k in a minivan/wagon setup.
My system is:
1 x ZeroFlex 5k
2 x ZeroFlex EVO 15's
3 x 100ah lithums
1 x 500farad cap bank

I've attached the spec my mate gave me and pix of the box, the port is 11" round x 13" long internal.
I am thinking of going 45's internal and changing the port to a horn style starting at 9 1/2" internal Caming out to a 11" external at 8" out side the box.

Currently only managing to get 149.8 at 46hz out of it sealed on dash which is way off where I'm aming for.
Cars resident frequency is 56hz.

Any help would be greatly appreciated thanks

Check out the youtube video on my car search [ 151.9 Saleen ] That was done with a single 12 on 4000 watts ..in the trunk of a car no pushing air into the cabin ...a true trunk car ...its all in the way you design your system . My car has under drive pulleys and barely pulls charging voltage one spare Batcap 2000 in the trunk when the video was done in 2010 ..with your equipment you should be doing a 158 ...

 

[hispls 5,000+ posts]

Can we see pictures of the vehicle? Pics of the vehicle with the box in?

What nominal impedance are you running those subs? Are you metering on the dash sealed DB Drag style or some other method?

I'd say if you said your goal was 150 you could probably find that moving things around or testing the other SPL gain tricks but 155 is going to take a lot of work without throwing more power at this.

First issue I see is that the box is too small by half. Try 10 cube net 20" port per cube 17" port depth then shorten the port a little at a time until you stop gaining (your peak may change so test test test and keep notes of what you changed and your peak freq and number). That said, 20 square inches per cube may be impractical, you may have to sacrifice port area if it's just too big to fit on your box without crowding something or whatever.



One of the members here who I let borrow some of my subs over the winter put up some good minivan numbers in his minivan type thing. Subs and port forward (right up to the b-pillar) also is known to do big numbers in no-wall builds so may be worth testing.

 

[Zeroflex]

The vehicle is a Honda Odyssey, subs are wired to half ohm cars fq 56hz. My other everyday drop box is doing 150.8's sealed on dash on the same amp with the same subs. Have attached pic of the two different boxes the burp and the daily drop box. I know I can get more out of this burp box just scratching my head as to what to change and try.

 

[Zeroflex]

Can we see pictures of the vehicle? Pics of the vehicle with the box in?

What nominal impedance are you running those subs? Are you metering on the dash sealed DB Drag style or some other method?

I'd say if you said your goal was 150 you could probably find that moving things around or testing the other SPL gain tricks but 155 is going to take a lot of work without throwing more power at this.

First issue I see is that the box is too small by half. Try 10 cube net 20" port per cube 17" port depth then shorten the port a little at a time until you stop gaining (your peak may change so test test test and keep notes of what you changed and your peak freq and number). That said, 20 square inches per cube may be impractical, you may have to sacrifice port area if it's just too big to fit on your box without crowding something or whatever.



One of the members here who I let borrow some of my subs over the winter put up some good minivan numbers in his minivan type thing. Subs and port forward (right up to the b-pillar) also is known to do big numbers in no-wall builds so may be worth testing.

Can we see pictures of the vehicle? Pics of the vehicle with the box in?

What nominal impedance are you running those subs? Are you metering on the dash sealed DB Drag style or some other method?

I'd say if you said your goal was 150 you could probably find that moving things around or testing the other SPL gain tricks but 155 is going to take a lot of work without throwing more power at this.

First issue I see is that the box is too small by half. Try 10 cube net 20" port per cube 17" port depth then shorten the port a little at a time until you stop gaining (your peak may change so test test test and keep notes of what you changed and your peak freq and number). That said, 20 square inches per cube may be impractical, you may have to sacrifice port area if it's just too big to fit on your box without crowding something or whatever.



One of the members here who I let borrow some of my subs over the winter put up some good minivan numbers in his minivan type thing. Subs and port forward (right up to the b-pillar) also is known to do big numbers in no-wall builds so may be worth testing.

Thanks for the reply. Have added a post with the pix of both my boxes in my wagon. One is my daily drop box doing 150's with that one the second is the burp box. Cheers

 

[Zeroflex]

What kind of vehicle are you using?

What is the resonant frequency of the vehicle?

What impedance is it rising to?


If you cant answer those questions then you need to take some measurements and do some tests and report back because that data is essential to getting louder.

2 15s on 5k should be an easy 150 but I doubt a 155 unless its in a CRX.

Please see response post. The cars a Honda Odyssey RB1.

 

[THATpurpleKUSH 5,000+ posts]

56hz seems like a high peak for such a large vehicle. Usually small cars peak high and larger body vehicles peak lower. But SPL makes no sense sometimes so who knows.

If you are wired to .5 ohms nominal, what is it rising to at your burp frequency?

Larger boxes tend to have less impedance rise, so going larger should cut down on the rise and allow you to clamp more power.

 

[Jeffdachef 5,000+ posts]

Please see response post. The cars a Honda Odyssey RB1.

56hz is not the peak for an odyssey your peak should be closer to 40-42hz. Lower your tuning. Raise the airspace. You also need to lower the airspace of the cabin, its a lot of space for you to pressurize so bigger box is key.

 

[Zeroflex]

56hz is not the peak for an odyssey your peak should be closer to 40-42hz. Lower your tuning. Raise the airspace. You also need to lower the airspace of the cabin, its a lot of space for you to pressurize so bigger box is key.

With my current daily music drop box my best on music is a 150.8 at 46hz. I might just try some testing from 40 and up to see any difference. Thanks for the reply

 

[Zeroflex]

56hz seems like a high peak for such a large vehicle. Usually small cars peak high and larger body vehicles peak lower. But SPL makes no sense sometimes so who knows.

If you are wired to .5 ohms nominal, what is it rising to at your burp frequency?

Larger boxes tend to have less impedance rise, so going larger should cut down on the rise and allow you to clamp more power.

Haven't tested impedance on burp that's a good point I should test that see what I'm clamping . Will try with a bigger spec box and see how we go thanks mate.