Rear Ported

[Blacksabbath25]

Hi Blacksabbath,

The Opticon 6 has 2 ports as the bass driver is in a separate enclosure. On the IKon 6 the bass port is forward facing, the mid rear.

ok i never new that i thought they were an open cabnet if you see what i mean so there are 2 ports on each speaker but a port at the back of each bass driver

 

[emperor's new clothes]

Cutaway of Opticon 8 here:

http://www.dali-speakers.com/media/1669/opticon-whitepaper.pdf

Bottom line, they sound damn good to my ears.

The OP could consider floorstanders from Proac, Neat and Tannoy that vent through their bottoms, no affinity to certain posters implied

 

[steve_1979]

Bass is omniderectional. It makes no difference if the port is on the front, back, top, bottom or side (unless you have the speakers so close to a wall that it physically obstructs the air flow from the port).

 

[Blacksabbath25]

Cutaway of Opticon 8 here:

http://www.dali-speakers.com/media/1669/opticon-whitepaper.pdf

Bottom line, they sound damn good to my ears.

The OP could consider floorstanders from Proac, Neat and Tannoy that vent through their bottoms, no affinity to certain posters implied

yes same for me my friend mine have opened up lovely and damn good to my ears too

 

[CnoEvil]

Bass is omniderectional. It makes no difference if the port is on the front, back, top, bottom or side (unless you have the speakers so close to a wall that it physically obstructs the air flow from the port).

 

I agree, as long as the Port isn't Starboard, that is.

 

[matt49]

Bass is omniderectional. It makes no difference if the port is on the front, back, top, bottom or side (unless you have the speakers so close to a wall that it physically obstructs the air flow from the port).

I think you'll find if you measure the SPL in the port, it'll be higher than in the immediately surrounding area, which would suggest quite strongly that more sound comes out of the port than through the speaker's walls.

Sometimes common sense is actually true.

 

[radiorog]

Nice to see the 'Thompson Technique' ...

I think I cracked the formula. Use common sense but be entirely devoid of any laws of physics applying to this Universe.

Back to regular program.

That's a shame it was just getting good

If Vlad was wrong, what is this guy doing....?

 

[Vladimir]

He won't get propoulsion if he plays ZZ top. He needs to play not AC but DC signal so the cones always push forward and make the car get forward momentum.

It's same like when you test a speaker with 1.5V AA battery. The cones will push forward.

Try it.

 

[Al ears]

He won't get propoulsion if he plays ZZ top. He needs to play not AC but DC signal so the cones always push forward and make the car get forward momentum.

It's same like when you test a speaker with 1.5V AA battery. The cones will push forward.

Try it.

He still will not go anywhere, he's parked up against the kerb.

 

[Vladimir]

He won't get propoulsion if he plays ZZ top. He needs to play not AC but DC signal so the cones always push forward and make the car get forward momentum.

It's same like when you test a speaker with 1.5V AA battery. The cones will push forward.

Try it.

He still will not go anywhere, he's parked up against the kerb.

You can just swap the positive and negative leads to have the cones go the other way, and so will the car.

 

[Vladimir]

Bass is omniderectional. It makes no difference if the port is on the front, back, top, bottom or side (unless you have the speakers so close to a wall that it physically obstructs the air flow from the port).

I think you'll find if you measure the SPL in the port, it'll be higher than in the immediately surrounding area, which would suggest quite strongly that more sound comes out of the port than through the speaker's walls.

Sometimes common sense is actually true.

At what frequency though? 600Hz is not bass. Did you check the graph posted by Dave?

 

[matt49]

At what frequency though? 600Hz is not bass. Did you check the graph posted by Dave?

As a matter of principle I never look at Dave's graphs. That way I sleep better at night too.

 

[davedotco]

At what frequency though? 600Hz is not bass. Did you check the graph posted by Dave?

As a matter of principle I never look at Dave's graphs. That way I sleep better at night too.

So I shall give you something else to worry about.

The near omni-directional radiation of bass frequencies is not caused by the vibration of the enclosure but primarily by diffraction, ie the bass energy is 'diffracted' around the speaker, hence the all round response. The bass frequencies produced by the port are also refracted in the same way as the frequencies produced by the drivers, however any port noise at higher frequencies is more directional, so rear ports are less noisy at the listening position.

Of course as a user of Martin Logan hybrids, you will be very aware of how the omnidirectional response of your bass enclosure is carefully integrated with the 'figure of eight' radiating characteristics of your dipole panels.

 

[matt49]

At what frequency though? 600Hz is not bass. Did you check the graph posted by Dave?

As a matter of principle I never look at Dave's graphs. That way I sleep better at night too.

So I shall give you something else to worry about.

The near omni-directional radiation of bass frequencies is not caused by the vibration of the enclosure but primarily by diffraction, ie the bass energy is 'diffracted' around the speaker, hence the all round response. The bass frequencies produced by the port are also refracted in the same way as the frequencies produced by the drivers, however any port noise at higher frequencies is more directional, so rear ports are less noisy at the listening position.

Of course as a user of Martin Logan hybrids, you will be very aware of how the omnidirectional response of your bass enclosure is carefully integrated with the 'figure of eight' radiating characteristics of your dipole panels.

No, not looking. *stop*

Anyway, my point remains: if you generate sound inside a box and then make a hole in the box, more sound will come out, and it'll come out through the hole.

 

[davedotco]

No, not looking. *stop*

Anyway, my point remains: if you generate sound inside a box and then make a hole in the box, more sound will come out, and it'll come out through the hole.

....and be defracted around the cabinet in line with the laws of physics.

Take any box loudpreaker or woofer enclosure with whayever drive units etc, you want, it doesn't matter, the dispersion is, effectively, spherical at bass frequencies. At higher frequencies the diffraction effects are not an issue and the dispersion patern simply becomes a function of diaphragm size.

 

[Vladimir]

Anyway, my point remains: if you generate sound inside a box and then make a hole in the box, more sound will come out, and it'll come out through the hole.

I have to agree with this.

There is more sound coming out of the back port hole than in front or the sides of the speakers simply because the hole isn't obstructed from a cone or walls.

 

[steve_1979]

Anyway, my point remains: if you generate sound inside a box and then make a hole in the box, more sound will come out, and it'll come out through the hole.

I have to agree with this.

There is more sound coming out of the back port hole than in front or the sides of the speakers simply because the hole isn't obstructed from a cone or walls.

That's what your instinct tells you and at higher frequencies you'd be correct. But the fact remains that low bass frequencies are omnidirectional and the bass coming out of the port will be just as loud in front or behind the speaker.

I know it goes against your instincts but that's what the laws of physics dictate and it's been scientifically proven many times. You can even try it yourself. Play an 80Hz sine wave through your speakers then turn them around by 180°[/b] and play the sine wave again. The bass volume won't change.

 

[Al ears]

Now I wonder if anyone told Tannoy that.

 

[Vladimir]

Anyway, my point remains: if you generate sound inside a box and then make a hole in the box, more sound will come out, and it'll come out through the hole.

I have to agree with this.

There is more sound coming out of the back port hole than in front or the sides of the speakers simply because the hole isn't obstructed from a cone or walls.

That's what your instinct tells you and at higher frequencies you'd be correct. But the fact remains that low bass frequencies are omnidirectional and the bass coming out of the port will be just as loud in front or behind the speaker.

I know it goes against your instincts but that's what the laws of physics dictate and it's been scientifically proven many times. You can even try it yourself. Play an 80Hz sine wave through your speakers then turn them around by 180° and play the sine wave again. The bass volume won't change.

No one listens to 80Hz tones Steve. This is real life and we listen to music at home. smh...

 

[steve_1979]

Anyway, my point remains: if you generate sound inside a box and then make a hole in the box, more sound will come out, and it'll come out through the hole.

I have to agree with this.

There is more sound coming out of the back port hole than in front or the sides of the speakers simply because the hole isn't obstructed from a cone or walls.

That's what your instinct tells you and at higher frequencies you'd be correct. But the fact remains that low bass frequencies are omnidirectional and the bass coming out of the port will be just as loud in front or behind the speaker.

I know it goes against your instincts but that's what the laws of physics dictate and it's been scientifically proven many times. You can even try it yourself. Play an 80Hz sine wave through your speakers then turn them around by 180° and play the sine wave again. The bass volume won't change.

No one listens to 80Hz tones Steve. This is real life and we listen to music at home. smh...

I almost replied then relised you'd slipped back into Thompson mode. *mosking*

 

[Vladimir]

Anyway, my point remains: if you generate sound inside a box and then make a hole in the box, more sound will come out, and it'll come out through the hole.

I have to agree with this.

There is more sound coming out of the back port hole than in front or the sides of the speakers simply because the hole isn't obstructed from a cone or walls.

That's what your instinct tells you and at higher frequencies you'd be correct. But the fact remains that low bass frequencies are omnidirectional and the bass coming out of the port will be just as loud in front or behind the speaker.

I know it goes against your instincts but that's what the laws of physics dictate and it's been scientifically proven many times. You can even try it yourself. Play an 80Hz sine wave through your speakers then turn them around by 180° and play the sine wave again. The bass volume won't change.

No one listens to 80Hz tones Steve. This is real life and we listen to music at home. smh...

I almost replied then relised you'd slipped back into Thompson mode. *mosking*

I thought you'd figure it out when I said the speaker cone is obstructing the sound coming out, unlike the port hole.

God, I just remembered when he used to put the quotes at the bottom of his replies. That was sooooo annoying. But he adapted since then. There is progress I think.

 

[philpot1001]

My first contentious post - I've arrived lol

 

[Covenanter]

I kinda think everything anybody says about speakers is at best partially true. We are talking about really complex systems here, far too complex for simple explanations. Putting to one side the interactions between electronics and speaker and between speaker and floor (sometimes wall), which are important in themselves, we have a device which puts out sound waves that interact with everything in your listening environment before hitting your ears. This interaction is affected by geometry (how far you are from the speakers, their separation and their orientation) and by the size of the room and the materials that make up the room and the furniture. Even atmospheric pressure and room humidity affect sound propogation, albeit probably in a very small way in most domestic circumstances.

This is why listening is the key thing to do before buying. I shudder when I read of people buying without hearing.

Chris

 

[matt49]

Anyway, my point remains: if you generate sound inside a box and then make a hole in the box, more sound will come out, and it'll come out through the hole.

I have to agree with this.

There is more sound coming out of the back port hole than in front or the sides of the speakers simply because the hole isn't obstructed from a cone or walls.

That's what your instinct tells you and at higher frequencies you'd be correct. But the fact remains that low bass frequencies are omnidirectional and the bass coming out of the port will be just as loud in front or behind the speaker.

I know it goes against your instincts but that's what the laws of physics dictate and it's been scientifically proven many times. You can even try it yourself. Play an 80Hz sine wave through your speakers then turn them around by 180° and play the sine wave again. The bass volume won't change.

No one listens to 80Hz tones Steve. This is real life and we listen to music at home. smh...

I almost replied then relised you'd slipped back into Thompson mode. *mosking*

There will be a prize for the poster who is able to maintain a Thompson pose for the longest time without anyone noticing.

 

[Blacksabbath25]

Also you got to take into account the differences in speaker technology not all speakers use the same technology in there construction . I was watching a utube video on speaker placement and how to set them up so the singer is in a tight window smack bang in the middle as well as the singer being projected at the right height . The person said that manufacturers put in there speaker handbooks that you have to have your speakers level , parallel , toed in , so far from the back wall and so on . This man was saying that you can tilt your speakers back , toe one speaker in heavily and so on . There is a video link on a post from the other day . I think the post was called speaker placement