Speaker foam port plugs? - AVS Forum
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post #1 of 11 Old 02-16-2011, 07:30 PM - Thread Starter
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Hello everyone,

I tried searching about the subject but couldn't find much info, I'm currently using a set of B&W speakers (683 fronts, 685 center (until I get a dedicated center speaker) & DM601 S3 for rear channels. I'm using a vtf 3 mk 3 HSU subwoofer.

They all came with foam port plugs, the ones that came with the 683s and 685 even have a removable piece in the middle of the plug to make it hollow (like this: http://img135.imageshack.us/img135/6350/portplug.jpg)

I'm currently running the entire set without any plugs, so my question is, how/when should I use those plugs to block the speakers ports either partially or entirely?

I guess trial and error is the best way to see how useful are those for me, but I'm asking here to get some info that would guide me in the right direction and to avoid damaging the speakers by doing something stupid that I'm not sure about...

Any help would be appreciated.

KRP-500M | Kuro 9G 5020FD + e-lite mod | B&W 683 Fronts | B&W 685 Center | B&W DM601 S3 Rears | HSU VTF3 MK3 Sub | Yamaha RX-V663 AVR
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post #2 of 11 Old 02-16-2011, 07:43 PM
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With my 683's I found I got the best balance bass with the half plugs. With the 685's that I use for surround speakers, I use the full plugs since they're close to the wall. Basically for me the 683's has a little bit of boomy bass, but I had them close to the wall, and the full plugs seemed to take the dynamics away by stiffening the woofer too much. The half plugs where perfect for me since it took the edge off the boominess while still letting the woofer move more free retaining dynamics. Now for the HTM61 center, I found the speaker to be a little muddy. I had to use the full plug in that one. Use the port plugs to tune the bass to your room/setup/personal preference.
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post #3 of 11 Old 02-17-2011, 01:39 PM - Thread Starter
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Thanks for the info man, IIRC you used to (or still do) run your 683s with a 663 Yamaha AVR and Emotiva power amp, have you ran into any issues with the setup after using it for a while (because I heard some pre outs are bad on some receiver so I don't know how reliable it is on the 663)? I'm thinking about adding a power amp to my setup, at least for the 683 fronts because they turned out to be more power hungry than I thought.

Any more comments/opinions about the main topic would be great.

KRP-500M | Kuro 9G 5020FD + e-lite mod | B&W 683 Fronts | B&W 685 Center | B&W DM601 S3 Rears | HSU VTF3 MK3 Sub | Yamaha RX-V663 AVR
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post #4 of 11 Old 02-17-2011, 08:18 PM
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Quote:
Originally Posted by metallicaband View Post

Thanks for the info man, IIRC you used to (or still do) run your 683s with a 663 Yamaha AVR and Emotiva power amp, have you ran into any issues with the setup after using it for a while (because I heard some pre outs are bad on some receiver so I don't know how reliable it is on the 663)? I'm thinking about adding a power amp to my setup, at least for the 683 fronts because they turned out to be more power hungry than I thought.

Any more comments/opinions about the main topic would be great.

I replied to one of your posts in the B&W thread but I also wanted to add that I did run my 663 into protection mode a few times with the 683. That's when I decided I was going back to using a separate power amp indefinitely (I always seem to wind up owning speakers with ohm dips where more current than an AVR can deliver comfortably is needed). I chose the Emotiva XPA-5 because I wanted a good bang for the buck like the Yamaha 663 and also wanted all my channels amplified.

The Yamaha's pre outs are good - no problem running the Emotiva XPA-5. In fact, I think my Yamaha 663 had better baseline sound quality than my new Denon 3311CI. I wish I could take the GUI, features, and Audyssey MultiEQ XT from the Denon and add it on top of Yamaha's baseline sound quality.
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post #5 of 11 Old 02-18-2011, 06:28 PM
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To decide whether you want to use the plugs, you have to understand what the plugs do, and for that you have to understand what the port does. Basically a ported or vented speaker uses the air inside the enclosure as sort of a compression driver. The "plug" of air in the port acts as a resistance to the oscillation of the air inside the cabinet when excited by the woofer - this is commonly compared to an oscillating spring with a weight at the end. The length & width of the port defines the amount of air in the plug, and therefore the amount of "weight". The longer the port, the more resistance, and the _lower_ the resonant frequency of the air in the cabinet. The foam plugs add more resistance to the port, and therefore lower the resonant frequency of the cabinet.

So what does this mean? Well, if you are hearing "boomy" bass in your speaker location & room then most likely the cabinet is resonating too high, and you want to lower the resonance by putting a half or a full plug into the port. If you have less bass than you want, then remove the plugs and see what happens.

It's important to remember that putting in the plugs tends to reduce the bass mainly by moving the resonant frequency lower in the spectrum to a point where the driver loses power. There's no substitute for a large, dedicated driver (i.e. subwoofer).
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post #6 of 11 Old 02-19-2011, 08:39 PM - Thread Starter
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@ Emig5m, I hate the protection mode, will definitely try to get a power amp at least for the front 2/3 channels if possible. Thanks for the confirmation about the 663's pre-outs being good too.

@ snoopdogg4600, that's one very informative first post :P, thanks.

KRP-500M | Kuro 9G 5020FD + e-lite mod | B&W 683 Fronts | B&W 685 Center | B&W DM601 S3 Rears | HSU VTF3 MK3 Sub | Yamaha RX-V663 AVR
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post #7 of 11 Old 02-20-2011, 12:18 PM
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Quote:
Originally Posted by snoopdogg4600 View Post

So what does this mean? Well, if you are hearing "boomy" bass in your speaker location & room then most likely the cabinet is resonating too high, and you want to lower the resonance by putting a half or a full plug into the port.

Great post, SnoopDog. Especially since it's your first. How about you post your ideas of port adjustment versus cabinet damping? Pros and cons of each?
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post #8 of 11 Old 10-19-2012, 09:44 PM
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A google searc h brought me to a place I haven't spent much time in...for a long time.
A couple weeks ago, I was given several links to a "bass Doctor" and he really got me thinking about proper integration of my sub to satellites...or as he would put it, integrating the system to the sub. One of the first things he suggests is port plugs. Right now I'm using socks, but I can definitely tell that this is the right move...I just to find a set now.
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post #9 of 11 Old 10-20-2012, 03:30 AM
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Quote:
Originally Posted by KennyG View Post

A google searc h brought me to a place I haven't spent much time in...for a long time.
A couple weeks ago, I was given several links to a "bass Doctor" and he really got me thinking about proper integration of my sub to satellites...or as he would put it, integrating the system to the sub. One of the first things he suggests is port plugs. Right now I'm using socks, but I can definitely tell that this is the right move...I just to find a set now.




Interesting. Could you post the links to the bass doctor you're refering to? A search didn't help me.
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post #10 of 11 Old 10-21-2012, 08:18 PM
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I got the wrong doctor...try this.
http://www.soundoctor.com/whitepapers/subs.htm
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post #11 of 11 Old 05-08-2013, 04:46 AM
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wow! the sound doctor was very helpful thanks
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