Finished my sealed sub but now want to make it ported?

AudioIsFun · 27th February 2004, 12:15 AM

I just finished my sealed sub made from a 12" SAE1204 and an ApexJr SR amp. It is a 95L ~ 3cu ft box. It does not hit as low as I would like, or is as loud as I would like. Also, it sounds kind of muffled. I was wondering if I made it ported, would this remedy my situation. I would like to have a louder and tighter (if that's how it is described) sub. Here are some plots of what I have and what I was thinking about. The yellow is of the sealed enclosure that I currently have. The green is what I was thinking about doing to my enclosure. I was thinking about cutting a hole in the bottom and inserting a 4" tube to tune it to ~23Hz. Would this fix my problem of the sub being not "tight" enough or loud enough? If not, what can I do to this enclosure to make it sound better. Please let me know. Thanks.

tool49 · 27th February 2004, 12:49 AM

Humm I might be wrong here, but I don't think that venting your sub will make it hit any louder. It will however make it hit lower as indicated by your graph. And from a general perspective, going vented is not going to make anything sound tighter, actually quite the opposite, most vented designs sound loose compared to sealed designs.

One thing that might play against you in a vented alignment is the fact that your woofer could go over XMAX given enough power in a very low frequency, thus giving a distorted sound and generally displeasant atmosphere.

Another thing not to forget is that your vent will take up some space in the box, roughly 4 liters, so your actual graph is a bit off the mark.

What about equing your sub with something like the ELF system on Rod Elliot's page? You might get that extension you are looking for while using your current sealed aligment. This system is relatively easy to build and would offer the enhancement you are looking for, I think.

http://sound.westhost.com/project48.htm

And if it all fails you could still vent your box and see if this is the sound you are looking for.

Another way to get a really hard hitting sub in this box would be to purchase another driver and put two of them in that sealed box. This would be a rather hard sub to drive with only one amp (2ohm) but it would give you a nice 3db higher sensitivity considering the losses. (3db is a lot more moving air!) This is expensive, and if I were you, I'd try the other options first.

Hope this helps!
Sébastien

Bill Fitzpatrick · 27th February 2004, 12:58 AM

Before you start cutting . . .

there are things to investigate.

How well is the sub blending with the main speaker? How is it crossed over? What are your main speakers?

Speaker/Listener placement in the room. Are you sitting in standing wave nulls? Have you experimented with placement?

Of course you could always put in the port and try it out. If it didn't solve the problem you could cover it up.

I would avoid using the term "tight" - it doesn't mean very much. "Muffled" doesn't go a very long way toward an apt description either.

AudioIsFun · 27th February 2004, 03:12 AM

OK, so I made a test cd. 20Hz - 60Hz in steps of 5Hz. I see my sub moving at 20Hz and 25Hz but I don't really start to hear or feel anything till 30Hz and then it is still just barely. At 35Hz I start to begin feeling vibrations and then I can hear and feel everything past that. What exactly does this tell me? That my box doesn't get low enough? If it is able to get low enough, should I be feeling vibrations around 20Hz? Please let me know. Thanks.

Ron E · 27th February 2004, 03:33 AM

Go ahead and try, if you don't like it plug the port back up. Another thing to try would be to make a ~40L sealed box and see how you like it - you could do this by putting 55L of bricks in the box you have now.

Bill Fitzpatrick · 27th February 2004, 04:37 AM

Quote:

Originally posted by AudioIsFun
OK, so I made a test cd. 20Hz - 60Hz in steps of 5Hz. I see my sub moving at 20Hz and 25Hz but I don't really start to hear or feel anything till 30Hz and then it is still just barely. At 35Hz I start to begin feeling vibrations and then I can hear and feel everything past that. What exactly does this tell me? That my box doesn't get low enough? If it is able to get low enough, should I be feeling vibrations around 20Hz? Please let me know. Thanks.

This really doesn't tell you more than you already knew. With room gain taken into consideration the curve you show for the sealed system should offer good low end response IF you don't have other problems such as poor location of the sub or listening chair.

Don't avoid dealing with issues relating to the effects of the room.

We still need to know what you are using for main speakers. I assume you have the level control on the subs turned all the way up?

ooheadsoo · 27th February 2004, 06:11 AM

Can you describe more how the sub sounds and at what point are you crossing it over to your mains?

AudioIsFun · 27th February 2004, 07:29 AM

Right now I currently am using Dayton BR-1's that I built. They are monitors but they are just filling in right now till I have some time to build a pair of tapered pipes by Andy G. The level on my amp isn't actually turned all the way up. I think I was reaching Xmax at a point. I thought I heard a clud sound, like it was hitting the magnet. There was a lot of movement that I saw and I didn't want to damage anything, so I turned it down. The subwoofer is also overpowering the BR-1's as they can not keep up. The amp is set at it's lowest crossover point which is 40Hz. The BR-1s are suppose to have response down to 46Hz, so I thought this would be ok. Please let me know what you think about my situation. I do also still have some noise coming from my receiver, hope this doesn't affect my situation too much. Also if there is any other information you need to know to help me out, I am full of answers. Thanks.

AudioIsFun · 27th February 2004, 07:34 AM

Quote:

Originally posted by ooheadsoo
Can you describe more how the sub sounds and at what point are you crossing it over to your mains?

Well, the sound is more of a feel than sound. When I am in my car and lets say I'm listening to a song with some bass, I will feel the bass very quickly and then it disappears. With the sub that I built, it seems to kind of linger a little bit and blend into the next "thump", as opposed to being two distinct seperate thumps. I'm not sure why this is; I would like to have it act more distinct between notes. Please let me know if you still need additional info. I hope this makes sense.

mats73 · 27th February 2004, 07:40 AM

Sure you could go ported, but you should tune the box lower(18 or 19 Hz perhaps).
Never tune a ported box for straight frequency response according to T/S. Unless you are using it outside maybe.

You can also knock of a few litres of the total volume if you go ported.

27th February 2004, 03:33 AM	#5
Ron E diyAudio Member Join Date: Jun 2002 Location: USA, MN	Go ahead and try, if you don't like it plug the port back up. Another thing to try would be to make a ~40L sealed box and see how you like it - you could do this by putting 55L of bricks in the box you have now. __________________ Our species needs, and deserves, a citizenry with minds wide awake and a basic understanding of how the world works. --Carl Sagan Science is a way of thinking much more than it is a body of knowledge. --Carl Sagan

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27th February 2004, 12:49 AM	#2
tool49 diyAudio Member Join Date: Apr 2003 Location: Montreal	Humm I might be wrong here, but I don't think that venting your sub will make it hit any louder. It will however make it hit lower as indicated by your graph. And from a general perspective, going vented is not going to make anything sound tighter, actually quite the opposite, most vented designs sound loose compared to sealed designs. One thing that might play against you in a vented alignment is the fact that your woofer could go over XMAX given enough power in a very low frequency, thus giving a distorted sound and generally displeasant atmosphere. Another thing not to forget is that your vent will take up some space in the box, roughly 4 liters, so your actual graph is a bit off the mark. What about equing your sub with something like the ELF system on Rod Elliot's page? You might get that extension you are looking for while using your current sealed aligment. This system is relatively easy to build and would offer the enhancement you are looking for, I think. http://sound.westhost.com/project48.htm And if it all fails you could still vent your box and see if this is the sound you are looking for. Another way to get a really hard hitting sub in this box would be to purchase another driver and put two of them in that sealed box. This would be a rather hard sub to drive with only one amp (2ohm) but it would give you a nice 3db higher sensitivity considering the losses. (3db is a lot more moving air!) This is expensive, and if I were you, I'd try the other options first. Hope this helps! Sébastien

27th February 2004, 12:58 AM	#3
Bill Fitzpatrick diyAudio Member Join Date: Jun 2001 Location: Eugene, OR	Before you start cutting . . . there are things to investigate. How well is the sub blending with the main speaker? How is it crossed over? What are your main speakers? Speaker/Listener placement in the room. Are you sitting in standing wave nulls? Have you experimented with placement? Of course you could always put in the port and try it out. If it didn't solve the problem you could cover it up. I would avoid using the term "tight" - it doesn't mean very much. "Muffled" doesn't go a very long way toward an apt description either.

27th February 2004, 03:12 AM	#4
AudioIsFun diyAudio Member Join Date: Dec 2003 Location: California	OK, so I made a test cd. 20Hz - 60Hz in steps of 5Hz. I see my sub moving at 20Hz and 25Hz but I don't really start to hear or feel anything till 30Hz and then it is still just barely. At 35Hz I start to begin feeling vibrations and then I can hear and feel everything past that. What exactly does this tell me? That my box doesn't get low enough? If it is able to get low enough, should I be feeling vibrations around 20Hz? Please let me know. Thanks.

27th February 2004, 06:11 AM	#7
ooheadsoo diyAudio Member Join Date: Jan 2004 Location: Los Angeles	Can you describe more how the sub sounds and at what point are you crossing it over to your mains?

27th February 2004, 07:29 AM	#8
AudioIsFun diyAudio Member Join Date: Dec 2003 Location: California	Right now I currently am using Dayton BR-1's that I built. They are monitors but they are just filling in right now till I have some time to build a pair of tapered pipes by Andy G. The level on my amp isn't actually turned all the way up. I think I was reaching Xmax at a point. I thought I heard a clud sound, like it was hitting the magnet. There was a lot of movement that I saw and I didn't want to damage anything, so I turned it down. The subwoofer is also overpowering the BR-1's as they can not keep up. The amp is set at it's lowest crossover point which is 40Hz. The BR-1s are suppose to have response down to 46Hz, so I thought this would be ok. Please let me know what you think about my situation. I do also still have some noise coming from my receiver, hope this doesn't affect my situation too much. Also if there is any other information you need to know to help me out, I am full of answers. Thanks.

27th February 2004, 07:40 AM	#10
mats73 diyAudio Member Join Date: Feb 2003 Location: Gothenburg	Sure you could go ported, but you should tune the box lower(18 or 19 Hz perhaps). Never tune a ported box for straight frequency response according to T/S. Unless you are using it outside maybe. You can also knock of a few litres of the total volume if you go ported.

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