help with port for a Fi 15" SSD

[Immacomputer 10+ year member]

ok for example...the 12volt port length calc
the formula they claim to use is ((14630000*(D/2)*(D/2))/((Fb*Fb*Vb*1728)-(1463*(D/2))))

I use 4" as the diameter simply because someone mentioned 4" aero port

I know how to calculate port length and that's not what I was asking about. You seemed all pissed that people said the port area was too small and that you trusted your formula. Picking port area is not just something you pull out of your *** (like you did here with choosing 4" for the diameter).

The reason the 4" port or the port area that you mentioned at the top of the thread is too small is because of the horrible port noise that you will get. Around tuning, the air in the port will be excited and will be moving back and forth like the sub does. The smaller the port area is, the faster the air will be moving. If the port area is too small, the air will be moving too fast and you will get turbulence. This turbulence can be heard and it will limit the output of the sub along with add a lot of distortion to your sound.

If I can find some time at home, I will try to draw up your enclosure and find a way to fit a port in there.

You may just want to go sealed. That sub should sound **** nice in a sealed enclosure of that volume.

 

[C-Bass 10+ year member]

I know how to calculate port length and that's not what I was asking about. You seemed all pissed that people said the port area was too small and that you trusted your formula. Picking port area is not just something you pull out of your *** (like you did here with choosing 4" for the diameter).
The reason the 4" port or the port area that you mentioned at the top of the thread is too small is because of the horrible port noise that you will get. Around tuning, the air in the port will be excited and will be moving back and forth like the sub does. The smaller the port area is, the faster the air will be moving. If the port area is too small, the air will be moving too fast and you will get turbulence. This turbulence can be heard and it will limit the output of the sub along with add a lot of distortion to your sound.

If I can find some time at home, I will try to draw up your enclosure and find a way to fit a port in there.

You may just want to go sealed. That sub should sound **** nice in a sealed enclosure of that volume.

My only concern is that when someone makes a comment like "You need more port area" and that's it, I'd like to know why.

It's been a LONG time since I played with this stuff, so I forgot most of whatever knowledge I had back then.

I did recall something about port speed and noise, but only after someone mentioned it first. As far as what to do with that info, that's another story //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

You say this sub would sound nice in a sealed box of this size. Can you explain why? The Fi website says it's not recommended.

I don't have anything against sealed boxes...and personally my way of thinking is that having a 15" sub should provide plenty of low bass (something I would normally want more of out of a smaller sub). Having it in a sealed enclosure would limit the boomy-ness and provide some more control to the sub...at least in my head

 

[Immacomputer 10+ year member]

My only concern is that when someone makes a comment like "You need more port area" and that's it, I'd like to know why.
It's been a LONG time since I played with this stuff, so I forgot most of whatever knowledge I had back then.

I did recall something about port speed and noise, but only after someone mentioned it first. As far as what to do with that info, that's another story //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

You say this sub would sound nice in a sealed box of this size. Can you explain why? The Fi website says it's not recommended.

I don't have anything against sealed boxes...and personally my way of thinking is that having a 15" sub should provide plenty of low bass (something I would normally want more of out of a smaller sub). Having it in a sealed enclosure would limit the boomy-ness and provide some more control to the sub...at least in my head

Fi's website doesn't say it isn't recommended, they just don't have any numbers for the recommended sealed volume size. If that means they don't recommend it, I would love to hear why.

If I was looking for a 15" sub for a sealed enclosure, the SSD would be one of the first subs I would consider. When sealed, the sub will have a nice low F3 around 35hz or so and it would still sound pretty tight as it's alignment would be around .8 Qtc. It has a mid Qts value, low Fs, medium Vas, high Qes, and a decent amount of throw which just screams "seal me" to me. It should dig pretty **** low sealed and should still have decent authority up top with all around decent SPL.

It would probably be your best route unless somebody else can figure out how to get a port into that. I failed at making one easy to do.

 

[C-Bass 10+ year member]

Fi's website doesn't say it isn't recommended, they just don't have any numbers for the recommended sealed volume size. If that means they don't recommend it, I would love to hear why.
If I was looking for a 15" sub for a sealed enclosure, the SSD would be one of the first subs I would consider. When sealed, the sub will have a nice low F3 around 35hz or so and it would still sound pretty tight as it's alignment would be around .8 Qtc. It has a mid Qts value, low Fs, medium Vas, high Qes, and a decent amount of throw which just screams "seal me" to me. It should dig pretty **** low sealed and should still have decent authority up top with all around decent SPL.

It would probably be your best route unless somebody else can figure out how to get a port into that. I failed at making one easy to do.

They mention it on the official Fi forums

but...

After doing way more research than I had hoped regarding this topic, I agree with you 100% There doesn't seem to be any reason why not

and it would also get me out of this situation

I would have definitely designed the box differently had I taken into account the port sq.in. etc,. I thought I was going to get away with the little ports in my first calculations..heh

If anybody is interested I can update this thread with the building progress

 

[Immacomputer 10+ year member]

Keep us updated.

I would love to know why Scott would not recommend this sub sealed. Maybe it's because it needs a good size sealed box to perform well? That would be a pretty shitty reason to not recommend it.

 

[C-Bass 10+ year member]

I don't know why either...

Thanks for all your help btw, appreciate you steering me in the right direction.