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hooplaaa
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port placement and size?
any information on where the best place on the box a slot port should be, the length between the outer part of the box and the slot would be greatly appreciated.
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 07-30-2004 05:20 PM |
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Bargersaudio
Member
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RE: port placement and size?
quote:
Originally posted on 07-30-2004 by hooplaaa
any information on where the best place on the box a slot port should be, the length between the outer part of the box and the slot would be greatly appreciated.
The port should always face into the listening area. As far as length between the outer wall and the port is no big deal. I usually use one side of the enclosure as part of the slot. This simplifies the construction process. You will notice most enclosures built use this procedure.
By the way welcome it is great to see a female interested in car audio.
Denny,
www.bargersaudio.com
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| 08-01-2004 07:16 AM |
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geolemon
Member
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RE: RE: port placement and size?
quote:
Originally posted on 08-01-2004 by Bargersaudio
The port should always face into the listening area. As far as length between the outer wall and the port is no big deal. I usually use one side of the enclosure as part of the slot. This simplifies the construction process. You will notice most enclosures built use this procedure.
By the way welcome it is great to see a female interested in car audio.
Denny,
www.bargersaudio.com
The port should not - certainly not by generalization, and the majority of the time by individual case application - should not face the listening space.
We're dealing with two phenomenon here:
1) sound waves that inherently exceed all interior vehicular dimensions. This is why "cabin gain" exists.
2) the phase of these sound waves, regarding a cone and port phase relationship that are already no better than 90 degrees apart.
Now, you throw in direct vs. reflected waves - which inherently aren't far apart in amplitude, given phenomenon #1 shown above.
What you end up with - if you want to generalize - is the following:
http://www.installer.com/tech/aiming.html
Granted, Eddie Runner has made some oversimplifications in an effort to make diagrams very clear - but the rules are sound, and any installer with any experience could tell you this without any of the technical reasoning I have given above.
If you want a "generalization" - both the subwoofer and the port should fire rearward - even though generalizations are 'generally' a bad idea, certainly no substitute for understanding... but it's very much untrue that you "generally" want your subwoofer and/or port firing forward, as both are primary sound sources, with an amplitude and phase relationship (which are really the same thing in this case... 'chicken or egg' sort of thing) that varies by frequency.
Treat them both the same way.
Good luck!
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| 08-04-2004 12:18 PM |
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Bargersaudio
Member
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RE: RE: RE: port placement and size?
quote:
Originally posted on 08-04-2004 by geolemon
The port should not - certainly not by generalization, and the majority of the time by individual case application - should not face the listening space.
We're dealing with two phenomenon here:
1) sound waves that inherently exceed all interior vehicular dimensions. This is why "cabin gain" exists.
2) the phase of these sound waves, regarding a cone and port phase relationship that are already no better than 90 degrees apart.
Now, you throw in direct vs. reflected waves - which inherently aren't far apart in amplitude, given phenomenon #1 shown above.
What you end up with - if you want to generalize - is the following:
http://www.installer.com/tech/aiming.html
Granted, Eddie Runner has made some oversimplifications in an effort to make diagrams very clear - but the rules are sound, and any installer with any experience could tell you this without any of the technical reasoning I have given above.
If you want a "generalization" - both the subwoofer and the port should fire rearward - even though generalizations are 'generally' a bad idea, certainly no substitute for understanding... but it's very much untrue that you "generally" want your subwoofer and/or port firing forward, as both are primary sound sources, with an amplitude and phase relationship (which are really the same thing in this case... 'chicken or egg' sort of thing) that varies by frequency.
Treat them both the same way.
Good luck!
Well I feel this is not correct in this situation. I assume she is planning on competeing. The only time the sub and port should face the rear of the vehicle is when it is in an open area of the vehicle. (example an suv, van,hatchback, etc.) in reality these enclosures facing rearward are still into the listening area. If you are constructing the enclose to be sealed from the rear of the vehicle, which from reading some of the other posts is the way I took it!(wall, or trunk with folding down rear seat) then by all means the sub and port should face forward.
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| 08-04-2004 02:03 PM |
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geolemon
Member
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RE: RE: RE: RE: port placement and size?
quote:
Originally posted on 08-04-2004 by Bargersaudio
Well I feel this is not correct in this situation. I assume she is planning on competeing. The only time the sub and port should face the rear of the vehicle is when it is in an open area of the vehicle. (example an suv, van,hatchback, etc.) in reality these enclosures facing rearward are still into the listening area. If you are constructing the enclose to be sealed from the rear of the vehicle, which from reading some of the other posts is the way I took it!(wall, or trunk with folding down rear seat) then by all means the sub and port should face forward.
Still untrue though, on the aiming, you missed the point.
Read that link.
And again, we're talking about wavelengths that exceed all interior dimensions of the vehicle.
This is critically important, because our sound waves are effectively pressurizing the vehicle uniformly... the direction the subs are firing is truly irrelevant (unless you have the odd high-mass/high compliance combination sub that has slight droop when firing upwards, as a few large cone subs do)...
What is important is the location of the cones relative to your interior.
And what is ideal - in any situation (competition has nothing to do with anything - you can consider it a measure of "what is better", if you like, as SQ judges will analyze accuracy of response, quality of sound - unless you are arguing that better sound quality isn't better?) is to locate the subs as far to the rear of the trunk as possible...
You don't need any space behind them, save for enough clearance that they don't strike anything on full excursion. In fact, you can benefit from a phenomenon known as "compound loading", by firing the subwoofer very closely into a hard surface - similar to rear firing at close proximity to the rear of your trunk/hatch.
And the benefit of compound loading can be explained in this same context - even though is commonly thought of as a sort of 'black magic'...
...that's just misunderstanding. Compound loading benefits the end user essentially because you are eliminating one direction where waves would have gone, reenforcing the other escaping energy in the other directions.
Very similar.
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| 08-05-2004 01:18 AM |
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Bargersaudio
Member
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RE: RE: RE: RE: RE: port placement and size?
quote:
Originally posted on 08-05-2004 by geolemon
Still untrue though, on the aiming, you missed the point.
Read that link.
And again, we're talking about wavelengths that exceed all interior dimensions of the vehicle.
This is critically important, because our sound waves are effectively pressurizing the vehicle uniformly... the direction the subs are firing is truly irrelevant (unless you have the odd high-mass/high compliance combination sub that has slight droop when firing upwards, as a few large cone subs do)...
What is important is the location of the cones relative to your interior.
And what is ideal - in any situation (competition has nothing to do with anything - you can consider it a measure of "what is better", if you like, as SQ judges will analyze accuracy of response, quality of sound - unless you are arguing that better sound quality isn't better?) is to locate the subs as far to the rear of the trunk as possible...
You don't need any space behind them, save for enough clearance that they don't strike anything on full excursion. In fact, you can benefit from a phenomenon known as "compound loading", by firing the subwoofer very closely into a hard surface - similar to rear firing at close proximity to the rear of your trunk/hatch.
And the benefit of compound loading can be explained in this same context - even though is commonly thought of as a sort of 'black magic'...
...that's just misunderstanding. Compound loading benefits the end user essentially because you are eliminating one direction where waves would have gone, reenforcing the other escaping energy in the other directions.
Very similar.
I have looked at the link! look closely at the pictures these are systems that are not sealed from the rear of the vehicle. You are right for that point. For competing you should try to make the cabin space as little as possible (either by a wall or sealing the rear trunk space from the rest of the cabin. Thus in theory facing the subs and ports forward toward the windshield and as high as possible. Again in some of her other forums she mentioned wanting to compete for spl a wall is the best overall solution for this the next option is constructing the enclosure to seal the space between the rear of the vehicle and the front of the vehicle. This link is not explaining that or showing any pictures of doing that. Their are a lot more links out their than just this one explaing this theory.
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| 08-05-2004 06:16 AM |
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Dynamic_Sound2003
Member
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DYNAMIC SOUND Car Audio, Video, and Performance
quote:
Originally posted on 07-30-2004 by hooplaaa
any information on where the best place on the box a slot port should be, the length between the outer part of the box and the slot would be greatly appreciated.
as far as the placement, as denny said, it really doesn't matter. if it is a single sub enclosure, you can do it on one side. you want to build it out of 3/4" MDF, so 3/4" is how far from the wall you want it, utilizing the wall as one side of the port. if it is 2 subs, the most common way is to put in between, but there are several companies that make them also on one side.
as far as where to face the port, it really depends on the vehicle and what sounds best. in most cases, toward the rear is te best, but not in all. in my demo car, i have the sub facing up and the put firing to the right side and it gets louder than any rear firing set-up i have ever had.
Jason, Owner
Dynamic Sound
www.DynamicSoundCarAudio.net
Orders@DynamicSoundCarAudio.net
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| 08-05-2004 12:29 PM |
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hooplaaa
Member
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You guys are getting too technical for me! While I appreciate your effort to expand my understanding of the science side of car audio, I've read and reread the posts and links and while I have a greater understanding, most of it went over my head. I'll give you guys a bit more info and hopefully for my application you'll give me answers i understand. LOL. I drive a 2001 Intrepid and I want it to be loud not for judge's at competitions, but for me and my passengers. My seats do drop down and I always have them down when I ride. I had a custom box built although it has not been installed and I want to know I have the best box design before I agree to have it installed. I have two 15" subs. The box is 4 feet long and they put the slot ports on top of the box all the way back from the subs. The slots are about 1' x 2" and the "port divider thingie" (the wood between top and bottom of the box, at the slot port) is about a 1/3 of the way down form the top. The box is divided for each speaker. Also, they didn't put the typical plastic piece in the slots.
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| 08-05-2004 12:45 PM |
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Dynamic_Sound2003
Member
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DYNAMIC SOUND Car Audio, Video, and Performance
quote:
Originally posted on 08-05-2004 by hooplaaa
You guys are getting too technical for me! While I appreciate your effort to expand my understanding of the science side of car audio, I've read and reread the posts and links and while I have a greater understanding, most of it went over my head. I'll give you guys a bit more info and hopefully for my application you'll give me answers i understand. LOL. I drive a 2001 Intrepid and I want it to be loud not for judge's at competitions, but for me and my passengers. My seats do drop down and I always have them down when I ride. I had a custom box built although it has not been installed and I want to know I have the best box design before I agree to have it installed. I have two 15" subs. The box is 4 feet long and they put the slot ports on top of the box all the way back from the subs. The slots are about 1' x 2" and the "port divider thingie" (the wood between top and bottom of the box, at the slot port) is about a 1/3 of the way down form the top. The box is divided for each speaker. Also, they didn't put the typical plastic piece in the slots.
if it is not for competing, then i would suggest to try the built enclosure out. in the end, it is your ears are what matters and if it performs at what you want it too, then you have what you want. as far as hitting harder, in your vehicle, 1 15" sub would actually hit harder than the 2. i would guess the enclosure is around 4-5 cu ft total, so 2-2.5 cu ft per sub. that si not much for a 15" in a vented enclosure. if you put 1 15" in that same sized enclosure, you would get way more excursion and end up with more bass. compare it to drums. if you use 1 15" with 5 cu ft of airspace, it is liek a large drum. if you put 2 15" in that same enclosure, then the airspace gets cut in half, not to mention some air being lost due to the back of the sub taking it up. the 2 subs will have less excursion due to the less of air, so they will perform like 2 small drums. 1 large drum will always hit harder and deeper than 2.
Jason, Owner
Dynamic Sound
www.DynamicSoundCarAudio.net
Orders@DynamicSoundCarAudio.net
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| 08-05-2004 01:08 PM |
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Dynamic_Sound2003
Member
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DYNAMIC SOUND Car Audio, Video, and Performance
quote:
Originally posted on 08-05-2004 by hooplaaa
Sorry guess I should have mentioned that the box is in total 8.5 cubic feet, so about 4.25 per sub.
ok, so that is a pretty good size enclosure, i think you will be happy with. that is not too far off from what a typical 15" would need for a spl comp, which would be around 6-7 cu ft per sub.
Jason, Owner
Dynamic Sound
www.DynamicSoundCarAudio.net
Orders@DynamicSoundCarAudio.net
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| 08-05-2004 01:18 PM |
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hooplaaa
Member
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what about the port size's and placement on the box? The box is 4 feet long and they put the slot ports on top of the box all the way back from the subs. The slots are about 1' x 2" and the "port divider thingie" (the wood between top and bottom of the box, at the slot port) is about a 1/3 of the way down form the top. I'm interested in the low bass out of the design. Part of my problem is if I except this box design it's mine. They won't build me another to compare the sound. Do the plastic pieces they put in the port serve any function?
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| 08-05-2004 01:24 PM |
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jntar
Member
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RE:
quote:
Originally posted on 08-05-2004 by hooplaaa
what about the port size's and placement on the box? The box is 4 feet long and they put the slot ports on top of the box all the way back from the subs. The slots are about 1' x 2" and the "port divider thingie" (the wood between top and bottom of the box, at the slot port) is about a 1/3 of the way down form the top. I'm interested in the low bass out of the design. Part of my problem is if I except this box design it's mine. They won't build me another to compare the sound. Do the plastic pieces they put in the port serve any function?
What brand of subs are they? Burgersaudio can design you a box and if he doesnt have time I can do it. But I need the model of the subs and amp. Also do you want the box just in the trunk or in the trunk and backseet as well?
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| 08-05-2004 02:06 PM |
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hooplaaa
Member
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RE: RE:
quote:
Originally posted on 08-05-2004 by jntar
What brand of subs are they? Burgersaudio can design you a box and if he doesnt have time I can do it. But I need the model of the subs and amp. Also do you want the box just in the trunk or in the trunk and backseet as well?
While I greatly admire someone who never stops working/selling, I have developed over the years a great business relationship with a shop here in town. I have utilized the discounts of purchasing equipment online and the exstensive knowledge base of fellow enthusiasts, but this kind of purchase I'm leaving to my guys at the house of car stereo.
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| 08-05-2004 02:25 PM |
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