Enclosure question for single 12" Fi Q

[The Camry]

When your tuned that low. You lose a significant upper range. So yes that 32 Hz will make a big difference. Are your doors sealed?

 

[Jeffdachef 5,000+ posts]

Port area seems slightly on the high side at 20 square inches per cubic foot. But anything less and I'd be pushing over 90ft/s of velocity through the port at tuning and that will create port noise. This design is already 80ft/s which is pushing it.

Too much port area narrows the bandwith and loses cone control. 20 port per cube sounds overly excessive.

 

[gamehawk55 10+ year member]

Too much port area narrows the bandwith and loses cone control. 20 port per cube sounds overly excessive.

It seemed a little excessive to me too but that was the only way I could get a 33hz tuning while keeping port velocity around 80ft/s, which is still a little on the high side I think.

 

[Jeffdachef 5,000+ posts]

When you try to find the feet per second for the port noise, you normally input the amount of power its getting. However for example a 2k amp, you dont put in 2k in the signal / power section because there is impedance rise, its more proper to put in a gauged amount of power after box rise. Or else your rear air velocity will always go through the roof excessively.

It seemed a little excessive to me too but that was the only way I could get a 33hz tuning while keeping port velocity around 80ft/s, which is still a little on the high side I think.

 

[gamehawk55 10+ year member]

When you try to find the feet per second for the port noise, you normally input the amount of power its getting. However this does not mean having for example a 2k amp, you dont put in 2k in the signal / power section because there is impedance rise, its more proper to put in a gauged amount of power after box rise. Or else your rear air velocity will always go through the roof excessively.

Well I'm running a T2500-1BDCP at 4ohms currently with a birthsheet saying 2200W @4ohms. So I'm putting in 1500W in the signal section. Pretty sure it's pushing 1500W since it's the constant power version of the amp. I'm trying to tweak it a bit in Torres but I'm not able to get it below 17-19sq inches per foot :/

 

[gamehawk55 10+ year member]

Wait a tick....When manufacturers give you a recommended box size...Are they quoting that as NET volume after all displacements? or Gross volume?

 

[Jeffdachef 5,000+ posts]

Wait a tick....When manufacturers give you a recommended box size...Are they quoting that as NET volume after all displacements? or Gross volume?

net

 

[Jeffdachef 5,000+ posts]

My FI Q 15 back then was in a 4 cubic feet net box tuned to 32 hz, with only 52.5 sq inches of port area so around 13 port per cube and it had no port noise at all. It played very low and linear blending to the upper hz range as in you hear it faintly but its there. However for metal, i'd suggest a different sub like an SSA Xcon, switched from an FI Q 15 to an ssa Zcon 12 and sound quality(to my ears and listening preferences) was astonishing. Tuned to 33hz and it hit everything loud and clear from up high and down low.

Well then I'm not sure how to get this box to a 32hz tuning while keeping the port area per foot down below 16 and the port velocity numbers under 100ft/s

 

[gamehawk55 10+ year member]

net

Well then I'm not sure how to get this box to a 32hz tuning while keeping the port area per foot down below 16 and the port velocity numbers under 100ft/s

 

[gamehawk55 10+ year member]

I can shrink the width of the port but that's just gonna up the port velocity alot.

 

[Jeffdachef 5,000+ posts]

I can shrink the width of the port but that's just gonna up the port velocity alot.

I dont think you will run into any port noise issues at all. I've ran with much less than optimum port area, got a pretty true to tuning sound with full sounding lows and no audible port noise at any given frequency.

 

[gamehawk55 10+ year member]

I dont think you will run into any port noise issues at all. I've ran with much less than optimum port area, got a pretty true to tuning sound with full sounding lows and no audible port noise at any given frequency.

K after toying around with it a bit I think I might have found the optimum box, minus the 101ft/s port velocity winISD is reporting me. But by shrinking the port from 3.5" wide to 2.75 and shortening the port to 34" from 44" I end up with exactly 16 square inches of port per foot and approx. 40 square inches total with a tuning of 32.6hz. Sound pretty good to you?

 

[gamehawk55 10+ year member]

It doesn't actually seem much different from the box it's in now but the port is 1" wider and has 7 more square inches of port vs the box it's in now. According to Torres the current box is 2.8cuft net tuned to 26-27hz with only 9sq inches of port per foot (gross) lol. So this new one should hopefully be a pretty noticeable difference.

 

[Jeffdachef 5,000+ posts]

thats fine, i'd go at least 34/35hz though. 32 didnt feel like it cut it for my rock/metal preferences.

 

[Jeffdachef 5,000+ posts]

before you do that, have you tested how low yours actually goes?

Download some of these super low songs and see if they can hit it.

https://onedrive.live.com/?cid=5B5DDB599B80E91B&id=5B5DDB599B80E91B%218242