Port Area

[ibanender 2]

Would you have any recommendations of a design model I could go with? Something to get me started on? Should i just do a basic 3cube up firing slot port design? Ive never reached outside of the boxes youve seen me post here, Id be able to build more complex, but really what would benefit me is out of my design abilities right now. Basically I dont know of a box design that I am safe saying would be good..(outside of what Ive done and am happy with)

Bottom line is pick something, start with it, if you think it could sound different, change the box, and learn from it. I know everything I know from building hundreds of boxes and observing changes.

Nice, way to contradict yourself just one paragraph later.

Care to point out where? There are multiple factors, I made points on all of them. No matter the motor force, if more air CAN be displaced, it should be bigger, and there is a point where it's too big. More motor force allows for bigger ports to work better.

No, just no. Where did you get this garbage from? Wherever it is you should stop paying attention to any of it and forget everything you think you know.

Prove it. Do you actually build anything, or just play in WinISD and read forums all day? Have you ever been a part of subwoofer design, at all?

I hope the makes sense part you are referring to are 95's posts and not the garbage Ibanender is spewing.

There are no rules of thumb that are always accurate, nor none in this case worth using. You should keep the port air velocity to an acceptable level which is EASILY modeled.

Since you're the modeling master, have you ever taken an accurate measurement to a port to test the validity of the velocity estimation? You're assuming it's correct, but have you ever tested it? How is what I'm saying garbage? You say it is, with no explanation.

I hope people aren't listening to your verbal diarrhea.

OP, use this to calculate port area.

Right, why listen to the guy who helped design the driver, has been using them for 4 months before a consumer did, continues to improve them, and is part of the reason why the driver he's using is the way it is. Clearly, a generic calculator is the best option, it knows more than I do about the sub.

[asb2106 1]

That's weird that you put identical fingerprints on every sub

Are you going to do any bracing? That's 150lb of subs on the baffle and a lot of open space. Don't forget to include that in your calculations if so.

I found a real nice calculator on port sizing, I'll see if I can dig that up for you.

Hehe thats good :-) ill do some vertical 2 in dowel and ihave added (edit typing error. On cell) .23, poles are actually 1 5/16.

Edited March 15, 2011 by asb2106

[thor02 2]

[95Honda 486]

I think where people get confused on this is what is actually happening with the port in respect to the enclosure.

The port is the primary contributor to system resonance in a 4th order vented alignment. The size of the enclosure and the area of the vent are really not included in this basic foundation.

Case in point. If you take an 8 cubic foot enclosure with a single 3" I.D. vent that is appropriately tuned for a desired resonance it works perfectly well. How do I know this? I have placed a Focal 8V4412 in this exact box and performed measurements using IMP, 15 years ago. The vent had the predicted resonance, the impedance peaks were where they were suppose to be and there weren't any erroneous driver behaviors. This is with an enclosure thas had roughly less than 1 square inch of vent area per cubic foot. Why did this work well? It was an 8 inch driver with roughly 7mm of 1-way throw being driven with 50 watts...

On the other hand, I have used 6" I.D. vents in 1 cubic foot boxes and they also behaved as predicted. I was doing some early designs with assisted 4th order alignments and a 1st generation Adire Brahma 12" subwoofer. Using a rane parametric EQ and trying to run the driver flat down to 20 Hz in a box this size required all of it's excursion at even moderate listening levels. This require a large amount of vent area to stay away from compression. The vent in this case was very long, all of it was outside the box. But is still behaved as a vent, the cone was heavily dampened at resonance and the impedance was where it should be. This was with an enclosure that had roughly 25 square inches of vent area per cubic foot of enclosure volume.

What is the point of these 2 paragraphs? Vent area has nothing to do with the enclosure size, but everything to do with the driver and power used. But again, this goes down to the basic foundation of this concept. I am not arm-chair quaterbacking this either, these are real world scenarios I have actually conducted myself.

That is all I am going to offer on this subject.

[///M5 2,833]

Ibanender I quoted your contradiction. I know you are just trying to change the subject.

As for experience, you shouldn't make assumptions on that either as they are wrong. Some of us question the whys when we do things and don't just accept it, you should think about that yourself for once.

[edouble101 314]

I think where people get confused on this is what is actually happening with the port in respect to the enclosure.

The port is the primary contributor to system resonance in a 4th order vented alignment. The size of the enclosure and the area of the vent are really not included in this basic foundation.

Case in point. If you take an 8 cubic foot enclosure with a single 3" I.D. vent that is appropriately tuned for a desired resonance it works perfectly well. How do I know this? I have placed a Focal 8V4412 in this exact box and performed measurements using IMP, 15 years ago. The vent had the predicted resonance, the impedance peaks were where they were suppose to be and there weren't any erroneous driver behaviors. This is with an enclosure thas had roughly less than 1 square inch of vent area per cubic foot. Why did this work well? It was an 8 inch driver with roughly 7mm of 1-way throw being driven with 50 watts...

On the other hand, I have used 6" I.D. vents in 1 cubic foot boxes and they also behaved as predicted. I was doing some early designs with assisted 4th order alignments and a 1st generation Adire Brahma 12" subwoofer. Using a rane parametric EQ and trying to run the driver flat down to 20 Hz in a box this size required all of it's excursion at even moderate listening levels. This require a large amount of vent area to stay away from compression. The vent in this case was very long, all of it was outside the box. But is still behaved as a vent, the cone was heavily dampened at resonance and the impedance was where it should be. This was with an enclosure that had roughly 25 square inches of vent area per cubic foot of enclosure volume.

What is the point of these 2 paragraphs? Vent area has nothing to do with the enclosure size, but everything to do with the driver and power used. But again, this goes down to the basic foundation of this concept. I am not arm-chair quaterbacking this either, these are real world scenarios I have actually conducted myself.

That is all I am going to offer on this subject.

Skip all other posts and read this one

[asb2106 1]

I think where people get confused on this is what is actually happening with the port in respect to the enclosure.

The port is the primary contributor to system resonance in a 4th order vented alignment. The size of the enclosure and the area of the vent are really not included in this basic foundation.

Case in point. If you take an 8 cubic foot enclosure with a single 3" I.D. vent that is appropriately tuned for a desired resonance it works perfectly well. How do I know this? I have placed a Focal 8V4412 in this exact box and performed measurements using IMP, 15 years ago. The vent had the predicted resonance, the impedance peaks were where they were suppose to be and there weren't any erroneous driver behaviors. This is with an enclosure thas had roughly less than 1 square inch of vent area per cubic foot. Why did this work well? It was an 8 inch driver with roughly 7mm of 1-way throw being driven with 50 watts...

On the other hand, I have used 6" I.D. vents in 1 cubic foot boxes and they also behaved as predicted. I was doing some early designs with assisted 4th order alignments and a 1st generation Adire Brahma 12" subwoofer. Using a rane parametric EQ and trying to run the driver flat down to 20 Hz in a box this size required all of it's excursion at even moderate listening levels. This require a large amount of vent area to stay away from compression. The vent in this case was very long, all of it was outside the box. But is still behaved as a vent, the cone was heavily dampened at resonance and the impedance was where it should be. This was with an enclosure that had roughly 25 square inches of vent area per cubic foot of enclosure volume.

What is the point of these 2 paragraphs? Vent area has nothing to do with the enclosure size, but everything to do with the driver and power used. But again, this goes down to the basic foundation of this concept. I am not arm-chair quaterbacking this either, these are real world scenarios I have actually conducted myself.

That is all I am going to offer on this subject.

Skip all other posts and read this one

Im not trying to sound like a smart ass here, (IM REALLY NOT! I KNOW NOTHING COMPARED TO Y'ALL AND YOUR SUGGESTIONS AND COMMENTS ARE VERY HELPFUL TO ME) but of coarse its based on amp power and driver config, ive never argued that infact I dont think even ibanter or whomever has either. Hes saying box size needs to be part of the equation. And to a certain degree hes right, cause your box needs to be a certain size to maintain the specifics of the port, and driver that your looking to use. So im taking everything into consideration, and not just one post.

Like Ive said in others, I dont come here for one peice of advise, I want to know what everyone thinks, what everyone recommends, and maybe even suggestions, those are nice.

When its all said and done some of the specific comments might not have anything to back them up, but to some degree the principles they speak of should be noted.

Im not defending or crossing anyone here, and Im grateful for info from everyone here

Unless you just post a link to someones post saying this is the only one to read - cause its not how I choose to do my research.

All the opinions here matter, thats how it helps me come to my conclusions, and without conflicting ideas the point of asking is gone.

AND im changing the design to a single port between 50-55 inches of port area. Id like to go up to 60 but if I do it just throws off the space i need with the added length required.

Edited March 15, 2011 by asb2106

[ibanender 2]

Ibanender I quoted your contradiction. I know you are just trying to change the subject.

As for experience, you shouldn't make assumptions on that either as they are wrong. Some of us question the whys when we do things and don't just accept it, you should think about that yourself for once.

If you actually read it, you'd see that I explained everything in detail, with no contradictions. If I was trying to change the subject, I'd insult your mother, your sexuality, and your intelligence.

Perhaps you should question everything you post when somebody questions your godliness. I'm done with you on this forum, period. There's no point in putting effort into anything you're associated with because it will just end in your rambling about things you've convinced yourself you know about and won't consider anything anybody else has to say.

[///M5 2,833]

Ibanender I quoted your contradiction. I know you are just trying to change the subject.

As for experience, you shouldn't make assumptions on that either as they are wrong. Some of us question the whys when we do things and don't just accept it, you should think about that yourself for once.

If you actually read it, you'd see that I explained everything in detail, with no contradictions. If I was trying to change the subject, I'd insult your mother, your sexuality, and your intelligence.

Perhaps you should question everything you post when somebody questions your godliness. I'm done with you on this forum, period. There's no point in putting effort into anything you're associated with because it will just end in your rambling about things you've convinced yourself you know about and won't consider anything anybody else has to say.

Re-read again. I quoted them very simply for you. Funny about the ramblings, you are obviously strucken by the site in the mirror. Big difference between us. I want to learn everyday and do, you I don't see that so much. Good luck with that in life.

As for being done with me, good the forum will be a better place. Go do some studying and come back though, its sad because you sure type like you have the capability to learn but somehow miss the steps along the way.

[Duran 387]

I hope people aren't listening to your verbal diarrhea.

OP, use this to calculate port area.

Right, why listen to the guy who helped design the driver, has been using them for 4 months before a consumer did, continues to improve them, and is part of the reason why the driver he's using is the way it is. Clearly, a generic calculator is the best option, it knows more than I do about the sub.

It's not generic if it uses woofer parameters to calculate port area.

You need to go back to English class and learn the definition of "generic".

[RAM_Designs 25]

Don't base port area on box size, base it on potential air displacement by the woofers in your install, and by the frequency you're tuning to.

[cubdenno 0]

I think where people get confused on this is what is actually happening with the port in respect to the enclosure.

The port is the primary contributor to system resonance in a 4th order vented alignment. The size of the enclosure and the area of the vent are really not included in this basic foundation.

Case in point. If you take an 8 cubic foot enclosure with a single 3" I.D. vent that is appropriately tuned for a desired resonance it works perfectly well. How do I know this? I have placed a Focal 8V4412 in this exact box and performed measurements using IMP, 15 years ago. The vent had the predicted resonance, the impedance peaks were where they were suppose to be and there weren't any erroneous driver behaviors. This is with an enclosure thas had roughly less than 1 square inch of vent area per cubic foot. Why did this work well? It was an 8 inch driver with roughly 7mm of 1-way throw being driven with 50 watts...

On the other hand, I have used 6" I.D. vents in 1 cubic foot boxes and they also behaved as predicted. I was doing some early designs with assisted 4th order alignments and a 1st generation Adire Brahma 12" subwoofer. Using a rane parametric EQ and trying to run the driver flat down to 20 Hz in a box this size required all of it's excursion at even moderate listening levels. This require a large amount of vent area to stay away from compression. The vent in this case was very long, all of it was outside the box. But is still behaved as a vent, the cone was heavily dampened at resonance and the impedance was where it should be. This was with an enclosure that had roughly 25 square inches of vent area per cubic foot of enclosure volume.

What is the point of these 2 paragraphs? Vent area has nothing to do with the enclosure size, but everything to do with the driver and power used. But again, this goes down to the basic foundation of this concept. I am not arm-chair quaterbacking this either, these are real world scenarios I have actually conducted myself.

That is all I am going to offer on this subject.

Skip all other posts and read this one

Im not trying to sound like a smart ass here, (IM REALLY NOT! I KNOW NOTHING COMPARED TO Y'ALL AND YOUR SUGGESTIONS AND COMMENTS ARE VERY HELPFUL TO ME) but of coarse its based on amp power and driver config, ive never argued that infact I dont think even ibanter or whomever has either. Hes saying box size needs to be part of the equation. And to a certain degree hes right, cause your box needs to be a certain size to maintain the specifics of the port, and driver that your looking to use. So im taking everything into consideration, and not just one post.

Like Ive said in others, I dont come here for one peice of advise, I want to know what everyone thinks, what everyone recommends, and maybe even suggestions, those are nice.

When its all said and done some of the specific comments might not have anything to back them up, but to some degree the principles they speak of should be noted.

Im not defending or crossing anyone here, and Im grateful for info from everyone here

Unless you just post a link to someones post saying this is the only one to read - cause its not how I choose to do my research.

All the opinions here matter, thats how it helps me come to my conclusions, and without conflicting ideas the point of asking is gone.

AND im changing the design to a single port between 50-55 inches of port area. Id like to go up to 60 but if I do it just throws off the space i need with the added length required.

asb2106,

Like you, I started researching port area. I started a while back. ~1 year ago. I can actually say Duran on here got me to first understand the relationship between the total displacement of the woofer being the primry spec used to determine port area. Followed by power applied. That is where modeling the enclosure comes in. You can use that equation from the link provided or rather the "calculator". my determination was that area is where it needs to be for maximum power and under 10m/s port velocity.

John from Acoustic Elegance answered my question by telling me to model my woofer/enclosure under the "max" power I am going to use. try to keep the port velocity as close to 20m/s or under if possible. You start to get distortion at 10 m/s. at 30m/s you have distortion levels ridiculously high,port turbulence, port compression and higher air lock.

Box volume is relevant when once you determine port area via modeling port compression/port velocity ,you apply that area and the box volume to get the port length for your desired port tuning frequency. That's it as far as box volume vs port area is involved.

One of the main things I have learned about proper port sizing is that the people who complain about ported boxes sounding crappy, if you remove the incorrect tuning, what they dislike is the sound of an undersized port. It's pure distortion. And it does sound like crap. Make it the proper size and it's pure bliss. no matter the music you listen to.

[asb2106 1]

Got the box done, ended up going with 56 sq in of port, 3.1 cubes net, tuned to 35 hz. LOVING IT TO DEATH!!

I ran the 6 subs in a series parrell, and the multimeter is putting the load at 1.1-1.2 ohms for the 6. Running them all off 1 RF1000BD.

Its different bass tho, it cant grab those LOW LOWs like a bigger woofer can, one song for instance is rick ross, aston martin music. That song made some smooth and loud lows with my SoloX, and got real deep and loud. With the 8s, its as loud, and low, but its just not the same. Now apply that to the other 99.92% of my music and it actually helps it out. It keeps the music cleaner, and able to be amped up a hair more without loosing the clean quality sound.

I really love the sound, and the beats from one small amp too. Im hoping to hold alittle wow factor cramming 6 woofers in the trunk of a kia spectra

Edited March 19, 2011 by asb2106

[sefugi 166]

Enclosure looks good, those 6 gotta have a little kick to them.

[asb2106 1]

.. just a little.:elol:

[///M5 2,833]

Its different bass tho, it cant grab those LOW LOWs like a bigger woofer can

Then tune lower, that isn't the subs fault.

[hondakilla98 29]

Do you have any audible port noise? If so, you could always look into some aero's, and I agree with m5 on a lower tuning. Which with aero ports would make it possible to tune lower, add port volume and cut down port noise.

[asb2106 1]

I cant port lower.. that's the largest enclosure I can fit in there, its playing the notes, they sound good, but an 8" driver just doesn't produce the lows the same as a 15...

This setup is the loudest I've had to date, and I think its cause of the fantastic box build. I couldn't be happier with it. There's NOTHING wrong with the box or porting. M5, and Honda, no audiblr port noise at all, I don't want anymore port volume really I think I found a perfect size for these woofers.

Just a question M5 BUT when did I fault the driver? I faulted the size of the driver, yes, but i think the only one to blame there is me for buying 8s.. your quote completely missed (and I wonder if you even kept reading) but I clearly stated it gets just as low, it just isn't the same..

But this leads me back again. I started by saying I love it, and mention little things that I found about it. And all everyone reads is the small negatives that have no bearing on my feelings (and everyone else's that's heard it THAT LOVES IT!).

It's perfect, it sounds great, gets low, sounds great, and makes me breakfast. Couldn't be happier.

Edited March 20, 2011 by asb2106

[asb2106 1]

Double post

Edited March 20, 2011 by asb2106

[///M5 2,833]

Just a question M5 BUT when did I fault the driver? I faulted the size of the driver, yes, but i think the only one to blame there is me for buying 8s.. your quote completely missed (and I wonder if you even kept reading) but I clearly stated it gets just as low, it just isn't the same..

It is a misnomer that large drivers play lower than small. If you claim it isn't the box, then its the ....

[asb2106 1]

Must be me then. I believe I hear a difference when different cone sizes are present, I have no proof of this, and I'm sure your right. So I don't want to argue. But thanks for your input on the matter.

[asb2106 1]

Some tweaking with the headunit and amp has resulted in even better results than what Ive had.

Ive got these 6 woofers moving!! With certain songs, Im seeing almost an inch of flex in the roof, and my windsheild is flexing quite a bit as well!.

HOLY SMOKES, I never thought I could accomplish that on a single RF 1000 amp.

I guess its the air that it moves thats really giving me the feel of some SERIOUS BASS!

We did this SUPER budget install this weekend, a Kenwood 8105D with 2 RF P1 15" subs. Super cheapo setup, but we decided to see how we could do on a box, we ended up with 5.2 cubes and 60 sq inches of port, and this SLAMS too!! I cant belive the air this thing moves. simply amazed at the bass it put out. and the customer was dancing in place with the biggest possible grin from ear to ear with what he spent. It was quite enjoyable to watch. (Like no joke, this jeep seriously flexes the roof a full inch, i know not hard on a cherokee - but we paid < 250 bucks!)

Edited March 21, 2011 by asb2106

[Hostility 0]

more info on box please, i have the same setup to build a box for coming up lol, 2 15" p1's in a cavalier

[asb2106 1]

outer dimensions were 38 wide, 22 deep, and 15.5 high. Port is 36.5 x 1.65 x 21" to tune it to 33 hz.

Subs face trunk, the port faces down, travels along the "back" of the box, and turns in.

some 200 watt subs and a 500 watt 2 ohm amp and your in business i guess! haha

[Hostility 0]

lol nice, fun to see what some cheap stuff can do sometimes