to port or not to port...

copperpipe

I have a pair of rti a3's and a pair of rti a1's. I find that in certain music playback (especially classical) that there is a warm / dronish sound coming from them; most notable with chello or piano. As a test, I taped some cardboard over the front ports on both sets of speakers which seems to help a lot, but the tone is still "off" somewhat.

Is it just my ears...? Would a higher model (maybe something in the lsi series) reduce this color somewhat, or is this just a standard signature from polk across all their speakers? I'm not unhappy with them, but I would like to correct that if at all possible. I'm using 2 different amps for testing, a marantz and an emotiva.

Any thoughts, ideas? Is plugging the ports (including the rear) a good idea? I have lost a tiny bit of bass but the rear ports are still open and I would like to know if I'm going to damage them by plugging the ports permanently, or if that would reduce the quality of the sound. I don't care if I lose bass, as long as I get a better sound out of what's left

steveinaz

Being a classical listener, you may want to look into higher-end monitors. Plugging the ports may lessen ultimate power output capabilities, but shouldn't otherwise affect them, if you don't mind the difference in bass tonal properties.

Search the web a bit, and you'll probably find a more "elegant" solution for port plugging...

For experimentation purposes, used stuffed socks.

Joe08867

You may also want to try getting them away from the wall a bit more. It sounds like they may be too close.

steveinaz

Here's an excellent thread on the topic (Dynaudio Focus 140) with measurements. Interesting...

http://forums.soundandvisionmag.com/showthread.php?451579-Plugging-Bass-Reflex-Ports

Joe08867

Thanks for that post Steve. It more than reinforces what I was saying.

tonyb

Sounds like you might be over driving them. What is the rest of your gear ? Source ? How about the room size ? Stands ? Away from the rear/side walls ? How loud do you like to listen ? A tad more info is needed.

rebuy

copperpipe wrote: »

I have a pair of rti a3's and a pair of rti a1's. I find that in certain music playback (especially classical) that there is a warm / dronish sound coming from them; most notable with chello or piano. As a test, I taped some cardboard over the front ports on both sets of speakers which seems to help a lot, but the tone is still "off" somewhat.

Is it just my ears...? Would a higher model (maybe something in the lsi series) reduce this color somewhat, or is this just a standard signature from polk across all their speakers? I'm not unhappy with them, but I would like to correct that if at all possible. I'm using 2 different amps for testing, a marantz and an emotiva.

Any thoughts, ideas? Is plugging the ports (including the rear) a good idea? I have lost a tiny bit of bass but the rear ports are still open and I would like to know if I'm going to damage them by plugging the ports permanently, or if that would reduce the quality of the sound. I don't care if I lose bass, as long as I get a better sound out of what's left

The front ports are not for low bass. They are for cabinet and driver resonance control. By closing the front ports, you will change the resonance of the cabinets where it is tuned to make a smoother response and help control spikes in those affected frequencies.

All box speakers have resonance and the front ports address these problems on their respective models. It's the ARC port.

The back port is the Power Port for lower bass. If you're over loading the speakers with to much bass, any speaker will have the same problems as described above. I have 4 RTI's and if don't load them up with the bass knob, I generally have none of the problems you're referring to.

copperpipe

Thanks everyone for your thoughts...

Some more details: The emotiva (which is what I'll be using from now on) is plugged into a motu firewire soundcard (a $600+ soundcard so not just some junky onboard stuff) from my computer, but I've switched it around with a behringer that I have as well, makes no difference either way. I'm in a rectangular room, though it's almost a square shape. My desk is in a corner, the a3's are on my desk right up against the wall. I didn't think that would matter since they come with little hangers and feet to attach to a wall (there is a little screw hook in the back of the power port), but I did try and move them forward 10 inches on my desk as well, don't think it had much effect.

I'm definitely not overloading them in any way; the emotiva has no bass / treble controls so it can only be run flat, and when I tested my marantz I had it set in 7.1 channel "direct"? mode (so again it is all flat). The soundcard has controls for all of that but they are all "off". The software (vlc) has controls too but here too the eq is disabled. I'm 4 feet away from the speakers trying to get work done, volume on the emotiva is b/n 1/4 and half volume, I can talk over the sound coming from the speakers. When I play dance / country / rock it sounds really good, it's just in a certain range like piano and some strings which really seem to make them drone; the speakers aren't straining in any way, it's just a color that I'm hearing.

I had some foam (leftover from underlay in my floor) that I rolled up and put inside both front and rear ports, it's pretty much gone now but I did lose more bass than I bargained on :sad: But since reading rebuy's message I will remove the foam at the front and have another listen. I generally don't like speakers that have ports but the price was too good too pass up on these. I generally listen to music the entire time through my speakers, sound quality for movies is not important at all.

tonyb

Ports aren't necessarily evil, you need to pay attention to what it will be used for and placement. Something up against a rear wall should be front ported. Rear ports need to be away from the wall unless they have a back plate to disperse the sound like some polk speakers do. That at least enables closer rear wall placement.

With that, maybe try turning on some equalization, setting them to small instead of large. I would move them out as far away from the wall as possible and remove the stuff you put in the ports. Play around with your settings more, see what options the soundcard gives you and go from there. Turning everything off can be doing more harm than good to the sound. How about side walls, they aren't in any kind of cubby hole are they ? Experiment a tad, you'll find better sound by adjusting settings and placement.

20hz

try whats called a variovent , its basically a 1/2" hole in the cabinet with a piece of medium density foam over it , what this allows is the speaker at lower volumes thinks it sealed but at higher volumes it flows air , more moles are needed for bigger speakers (my 12" subs had 3 holes ) .
As a test you could make a couple of wooden discs that slip in the port loosely and use foam or felt to secure them via tension once that works you can try differant holes , the foam I used was 1/2" and it looked like heavy duty carpet foam .
It worked good my 12" subs went below 20 hertz .
I realize sub sound is not your desire or goal but the concept to tune the sound is still there and should work , speaker placement will make a big differance or just get a unit with the Audessy system and that will tune your room and your speakers for you

gce

tonyb wrote: »

Rear ports need to be away from the wall unless they have a back plate to disperse the sound like some polk speakers do. That at least enables closer rear wall placement.

So are you saying that say the RTiA7's with the backing plate on the rear port can be put close to the wall as long as they are clear on both sides to work properly?

steveinaz

The back plates help, but you're still going to get "extra" bass reinforcement if too close to the wall because of close boundry proximity. If you want clean bass, I'd recommend any port arrangement be at least 12" off the back wall (from the rear of the cabinet), but rear ported will be even more sensitive to close placement.

tonyb

gce wrote: »

So are you saying that say the RTiA7's with the backing plate on the rear port can be put close to the wall as long as they are clear on both sides to work properly?

Closer to the rear wall, but I wouldn't stick them up against a rear wall. Like Steve suggested, around 1 foot would be min. I would think. Of coarse it's all give and take, playing around with placement is almost a must do to achieve good results. Point is, keep in mind where you want speakers, for what application, before deciding on what to get. Don't buy speakers first then try and figure out how to make them work in your environment.

gce

tonyb wrote: »

Don't buy speakers first then try and figure out how to make them work in your environment.

So, that was my first mistake...huh! LOL... They do sound ok. I just want to improve them as much as I can. Don't have much room to move them away from the wall. I may try plugging ports to see the difference it makes, if any.

Thanks for your help!

tonyb

I appologize my friend, didn't mean to make it sound like a knock on you. I was speaking in general. LOL....damn, that did sound horrible didn't it ? Again, my appologies.

gce

tonyb wrote: »

I appologize my friend, didn't mean to make it sound like a knock on you. I was speaking in general. LOL....damn, that did sound horrible didn't it ? Again, my appologies.

Hopefully your not appologizing to me because it's not necessary! I've been on this forum for awhile and can't thank you and others enough for all the help in this hobby. I just received my copy's of Abbey Road, Let it Be and the White Album form Amazon. Moved my speakers away from the wall a little and I have say it does sound better!

tonyb

Yes, appologies to you GCE, doesn't matter how long one has been around the forum, that did sound terrible even though I didn't mean it that way. Glad your own situation improved some.

I know we all have our own certain restrictions when it comes to speaker placement in a given room, not to mention the wife factor on top of it all. Sometimes just a few inches can make a difference. Regardless, my aim is to get people to simply think more about setting up speakers for the intended application before dropping hard earned coin on something that won't work for you.