Find out how the port is being employed by the speaker - in other words, find out what frequency range goes to the port. If that is the area you need to cut, then you should consider it (might want to discuss with the manufacturer to be safe).
My dealer had to stuff the ports to get Wilson Sashas to work in my room. In my case, it reduces the lowest frequencies, but that's what the room called for. |
I have not read all of these theads, so this may have been handled. Do not stuff anything in your ports. The ports are designed to give you a flat or smooth bass response down to a speakers given ability.(Some small speakers build a bass boost on purpose). If you are using quality speakers, you are dealing with a room problem amplifying a given bass frequency. Try moving your speakers out from all walls, you have an underdamped amp, change your amp or even cables for control. Or you can change the speaker design slightly. The way to remove boom is to remove the port and exchange the port tube. You will need to lengthen it. This lowers the tuning freqency and will also decrease any bass hump caused buy tuning. If you shorten it, you will create more bass at probably an undesireble frequency.
I hope this helps. |
Agree with Pani. Try using the Sumiko Master Set method to set up your speakers. It will take a while but you will learn to find the bass nodes in the room and correct for any boominess. |
I had a pair of B&W's with what they called "bungs." I always got a kick out of that one. Seriously though, can every speaker have it's port sealed off? Could this damage a woofer in a design that was intended to "breath" more. |
didnt bother to read the other posts, but you do realize that you paid your monies for the design of your spkrs, therefore then you realize that your spkrs were designed to have a port, for a very particular reason....boom is most likely a result of your placement of your spkrs w/in your room. move them away from room boundaries? seems obvious. |
There is a very fundamental theory of room acoustics which no one has mentioned yet. Place the speakers at one of the room nodes and see how the boom reduces drastically. So how do you find out a room node ? It is simple, play a bass track which typically has an overhang in your room. Connect one speaker at a time (disconnect the other speaker). Stand next to the speaker that is playing, move around the speaker listening for the location where you hear the maximum overhang. You can just move within a radius of 1 foot form the existing location of the speaker and find out the spot of maximum bass/overhang. Once you locate it, place the speaker right at that spot. Repeat the same for the other speaker. You may have to move them inches to get the right imaging but for sure your bass issues would be reduced. You may even do this for one speaker, which you think is causing the maximum boom, this also you can ensure by playing a single speaker at a time and listening from your sweet spot to determine which speaker is causing more boom. Do it for that speaker, keep it fixed at that location and move the other speaker around for imaging and staging. Try it !! |
Depends on the speaker, but if you have a three or more way speaker and multiple ported chambers, you could have some frequencies drop out if the mid woofer driver/crossover combo is "looking" to the port for bass reinforcement. Probably not common, but possible. |
"Sealing" the port is a bad idea. The drivers and crossover were designed to work with the port open, at least to some degree. Knownothing, how would it affect the crossover? Here's an example what you're effectively doing when a port is plugged. http://yfrog.com/4jw26fxsealedvsportedj |
I had a pair of Dynaudio Focus 140s. They came with port plugs. I like the sound with them in better in my bedroom system. Just too much boominess without them. They sounded great with the ports plugged. And it was very easy to pull them in and out for experimentation though it was immediately clear to me that they were best left in for my setup. |
I stuffed the port with polyfill. I guess if you completely cut off the airflow in the port the movement of the drivers will be compromised.
The ports are shaped like an "L" I think and are big (I can fit my hand inside). I don't know how I would be able to modify the port size without a lot of construction.
I haven't had this problem in this room (and in the same place) with other speakers (B&W, Polk, JBL, Infinity 7). |
Thanks, Mapman! I use a modular port system in many of my designs, and on several occasions being able to ship a longer center section to a customer has saved the day. The ability of the end user to make this sort of adjustment is a significant, and under-appreciated, advantage of ported enclosures over most other types. There is simply too much variation on boundary reinforcement from one room to another, as well as from one location to another within a room, for a successful "one size fits all" approach to bass tuning. Imho, of course. Duke |
What did you stuff the port with? If you think it sounds better you should find some porous foam material and cut it to fit properly. That should work without any negative side effects. |
I like Duke's ideas!
I've seen the port diameter trick done professionally to improve performance.
Never tried the straws approach but it sounds good! |
There aren't many placement choices when I room is 13x15. Speakers can only be so close to you. The Cardas site recommends (width of room)x(.447)=distance of speaker front to rear wall. That would be 5.5' for me almost putting them in the middle of the room.
I stuffed the ports and they sound pretty good, much better then when I first auditioned them. But maybe there could be some adverse effects when the woofer is sucking in air thru the port. It might not have enough air available to push as per design. |
I agree with the "bad idea".
I have tried it mulitple times over the years, and agree with Knownothing.
Speakers are designed for a purpose, either ported or sealed.
You really won't get the both of best worlds in home audio anyway (alot of full range car speakers are infinite baffle designs and work good ported or sealed).
When I tried stuffing the ports in the past, I gained nothing, and lost alot as far as soundstaging, and bass goes.
Nothing wrong with ported speakers provided they are set up in your room properly.
If you have problems with ported designs, its either that your room has problems, the position of the speakers, or the port is in the front and you are listening near field.
I am a sealed speaker man myself (I (insert heart here)) love my NHT M6's, provided there is good amplication available.
Nothing at all wrong with ported speakers, just experiment to find the best placement.
I have a feeling thats the only problem with your speakers. |
An in-between solution would be to change the port dimensions and thereby lower the tuning frequency. If you make the port longer, or narrower, the tuning frequency will be lowered and the bass will start to roll off higher up and more gradually. A slightly smaller diameter tube can be inserted into the port (ring the inner tube with electrical tape in two places to get a good friction fit). This smaller tube can be longer than the original port. Or, you can do it with straws, as long as they are likewise longer than the original port. Pack the straws in tightly until they deform into a honeycomb-like shape. You will probably have to remove the woofer if you do the straw-pack, so that you don't accidentally push the straws into the enclosure and end up with a pile of straws at the bottom.
How long should you make the insert? As long as possible, leaving about one diameter of clearance from enclosure walls or woofer magnets (like if the insert is 2" in diameter, you want at least 2" of clearance). If the bass is still boomy, go ahead and seal the box. If you overdid it and the bass is now too lean, the shorten the insert.
Duke
dealer/manufacturer |
thanks, you are exactly right. can you hear chug? i.m sure it,s there when cheap speaker manufactures like the one in framingham mass use a cardboard tube. ha. the nice looking aerodynamic fluted ports look cool. why is the velodyne ports slotted across the bottom of the cabinet? guess they would claim measurements of response show an advantage. this is why the inventor side of audio is cool to me. so many different ways to try and produce a sound wave accurately. thanks |
The straw thing was more of a port noise reducer...port chug, and not boom. Two different things.
Dave |
no one mentioned it unless i missed it but at one time people put soda straws into port to 'control' the air movement. i tried it and never heard a difference and the muticolored straws kept dissappearing as child stole them. i can,t be the only person who endures all these pranks/tweaks recommendations. ha |
"Sealing" the port is a bad idea. The drivers and crossover were designed to work with the port open, at least to some degree. The suggestions to play with positioning away from boundaries and partially blocking the port with foam or even a sock are legit. |
Foam plugs are really easier than socks.
With socks you have to have the right size and roll it up fairly loosely so not all air is blocked in the port. You usually want only partial obstruction of the air flow through the port.
BTW I also recommend tweaking placement away from corners and walls as the preferred soluton, but obstructing (not sealing) the port is an easy option if that is not possible. |
Acquaintance of mine tried the sock in the port thing in brand new speakers. Blew out when he cranked it up. Well, that became a game of how far the sock could fly. Two weeks later, the speakers went in for warranty repairs. Just an anecdote. |
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Trying the post sealing is a free experiment.Doing this may kill of the low frequency's too.I'd consider the placement idea for sure. |
my boominess problem went away with installing morrow audio interconnects. maybe bass or signal smearing is the problem. i never quit trying to find solutions to these less than earth shaking[ha] situations. thanks |
>08-24-10: Ifsixwasnin9
Great responses. Actually I stuffed the ports then I took out the woofer to see what was in the cabinet and the woofer is completely sectioned-off with pieces of foam! So I have to find out where the port is getting its bass from: I have to remove the other drivers.
Low frequency waves will go right through the foam. High frequency waves won't. So driver output in the port's pass-band excites its resonance, but higher frequencies off the backside of the driver (which are obviously 180 degrees out of phase with what's coming off the front side) don't escape from the port. |
Try moving them out away from the wall a few inches at a time....it should help a lot.
Dave |
Great responses. Actually I stuffed the ports then I took out the woofer to see what was in the cabinet and the woofer is completely sectioned-off with pieces of foam! So I have to find out where the port is getting its bass from: I have to remove the other drivers. |
Go to the Cardas site and use their room placement guide. Helped my speakers and cost nothing except the effort to move the speakers. |
I had a serious boom problem that was practically eliminated by repositioning the speakers. Sometimes, the problem is the room.
Try the following experiment: if your room dimensions are x by y, put the speakers at 1/4 x and 1/4 y from the respective walls. You might not like what they sound like there--they may sound a bit thinner than what you are used to--but what you are after here is to see if the boom goes away.
If it does, then your primary source of boom is probably room-related. It's a pain in the posterior to deal with, but the laws of physics are not mere suggestions... |
Partially blocking ports is a valid option. You have to try it and see.
Yes, I have in fact even used socks on occasion to do it. |
I agree with stuffing the ports too. You may want to position them differently (more or less toe-in - closer or farther from front or side walls - etc).
If what you are asking about adding 'fill' as in adding sand or shot to them that will tighten the sound from top to bottom. Try one thing at a time. Adding 'fill' may also make them forward sounding .
That's my opinion and good luck |
Hey Ifsixwasnin9, put a sock in it.
Seriously, I owned a pair of Acoustic Energy speakers that came with port plugs. The speakers had more bass than was needed in my small room. With the plugs inserted the bass was much tighter and tuneful. Give it a try.
Nice screen name BTW. |
