Markbass 4x10 cabs Rear ported vs. Front ported?

[Lesfunk]

What can I expect the differences to be? What does each design give me?
Anyone?

[JimmyM]

the front ported cab is bigger, so it will be heavier on the bottom. if they were the same size, there would be no difference.

[murphy]

I find it depends on how close a wall is to the rear ported cab...changes the sound.
I can get a more consistent sound from a front ported cab.

Now...runs and hides behind the wall

[JimmyM]

Originally Posted by murphy

I find it depends on how close a wall is to the rear ported cab...changes the sound.
I can get a more consistent sound from a front ported cab.

Now...runs and hides behind the wall

you really only need a couple inches clearance.

[T-Bird]

Hi.

There shouldn't be any difference at all.

That said, the location of the ports in relation to the speaker cones does make a difference if the ports "leak" mid- or high frequencies because of poor placement/poor cab dimensions.

Regards
Sam

[Arjank]

Originally Posted by T-Bird

Hi.

There shouldn't be any difference at all.

That said, the location of the ports in relation to the speaker cones does make a difference if the ports "leak" mid- or high frequencies because of poor placement/poor cab dimensions.

Regards
Sam

Allmost all commercial ported 210's, 410's will "leak" some unwanted frequencies because of poor design.

[billfitzmaurice]

Originally Posted by murphy

I find it depends on how close a wall is to the rear ported cab...changes the sound.

How close the cab is to a rear wall affects the sound of all cabs, including sealed.
OP, the rear ported is rear ported because the cab is too small for them to fit on the front. Jimmy correctly diagnosed the difference between the two options.

[Lesfunk]

Another cab I was looking at was the Markbass classic 6x10 sealed box.
I am confused. The Markbass site says they're discontinued while the Musisians Friend site says they're coming in in July.
Anybody know about these?

[JFN]

I've used a friends Markbass rear ported 4x10 and I own two of the Markbass front ported 4x10's. I found the front ported cab to sound deeper, bigger, and bit more aggressive, if that means anything. The description of the differences between rear vs front port cabs on the Markbass website describes it pretty well. The Markbass rep here on TB (can't think of his name off the top of my head) has also posted about the differences. Hope this helps.

John

[rmars]

Originally Posted by billfitzmaurice

How close the cab is to a rear wall affects the sound of all cabs, including sealed.

Thanks for confirming that Bill. I've played some super small stages this last year where my front port cab almost touched the wall behind it and my bass sounded very different. I had about a dozen arguments with the guitarist (whose also a bassist) about this and he said it shouldn't make a difference because my cabinets front ported and claimed I had no idea what I was talking about.

[billfitzmaurice]

Originally Posted by rmars

I had about a dozen arguments with the guitarist (whose also a bassist) about this and he said it shouldn't make a difference because my cabinets front ported and claimed I had no idea what I was talking about.

A guitarist who knows how speakers work? I guess there's a first time for everything, but he's not it.
Not only is port output omni-directional, so is the cone output below roughly 200Hz, so the distance from the wall has a major effect on low end response. The technical explanation of the how and why is called Allison Effect (after Roy Allison). Tell Einstein to google it.

[rmars]

Originally Posted by billfitzmaurice

A guitarist who knows how speakers work? I guess there's a first time for everything, but he's not it.
Not only is port output omni-directional, so is the cone output below roughly 200Hz, so the distance from the wall has a major effect on low end response. The technical explanation of the how and why is called Allison Effect (after Roy Allison). Tell Einstein to google it.

LOL! Will do Bill, you pretty much got this guy pegged. Thanks for the explanation as to why this occurs.

[Arjank]

Yup, this effect is easy to visualize.
Think about the low frequency waves as a big round sphere. When the cabinet was floating in mid air the sphere radiates energy in all directions (full space or 4pi).
When you put the cab on the ground the sphere is cut in half (half space or 2pi) so the energy level of the part of the sphere that is above the ground increases (with 6dB).
Put the cab on the floor and to a wall (quarter space) and you will gain another 6dB. This is only in theory, in a practical situation these numbers are slightly lower.

[billfitzmaurice]

Originally Posted by Arjank

When you put the cab on the ground the sphere is cut in half (half space or 2pi) so the energy level of the part of the sphere that is above the ground increases (with 6dB).
Put the cab on the floor and to a wall (quarter space) and you will gain another 6dB.

That describes space loading, not Allison Effect. Allison Effect is when the reflected wave off a boundary meets the original wave 180 degrees out of phase, and the two cancel each other out. That happens when the source is 1/4 wavelength from a wall, floor or ceiling, in the case of electric bass roughly between 1.5 and 7 feet. Most of the time Allison effect is bad news, though in a boomy room you can use it to cancel boom frequencies by having the cab the correct distance from the wall, and by the same token lifted off the floor.

[Arjank]

Originally Posted by billfitzmaurice

That describes space loading, not Allison Effect. Allison Effect is when the reflected wave off a boundary meets the original wave 180 degrees out of phase, and the two cancel each other out. That happens when the source is 1/4 wavelength from a wall, floor or ceiling, in the case of electric bass roughly between 1.5 and 7 feet. Most of the time Allison effect is bad news, though in a boomy room you can use it to cancel boom frequencies by having the cab the correct distance from the wall, and by the same token lifted off the floor.

Ah, I thought we were talking about something else.

Well, I didnt know what you were talking about was called the Allison effect. I know the effect and it's troubles. Í had loads of discussions with the so called sound engineers on stage when I wanted to move my cab to a different place to get a better(more even) bassresponse.

[billfitzmaurice]

Originally Posted by Arjank

Well, I didnt know what you were talking about was called the Allison effect. .

Roy Allison is identified with this, though he certainly wasn't the first to be aware of it. He was a major member of the 1950s-70s Boston speaker industry that included Tony Hoffman, the author of Hoffman's Iron Law. Roy now lives about five miles down the road from me.

[Mulebagger]

Bill, is there any appreciable difference in percieved volume between a rear ported, a front ported, and a sealed cabinet? Or are the differences primarily in tone/ punchiness. Sorry for the primitive terminology

[billfitzmaurice]

Originally Posted by Mulebagger

Bill, is there any appreciable difference in percieved volume between a rear ported, a front ported, and a sealed cabinet?

Between front and rear ported, no. Between ported and sealed, very much so. On average a ported cab is 4dB more sensitive than sealed in the low end. That's the equivalent of more than doubling the watts.

[Mulebagger]

Holy Smokes!!!!
I didn't know it was that large of a difference.
Concerning rear ports.. I've read on one post where it may be bad placement for the rear port to be directly behind the speaker...
But I've had BagEnd cabs that had that design.

Any porting red flags I should avoid?

[billfitzmaurice]

Originally Posted by Mulebagger

I've read on one post where it may be bad placement for the rear port to be directly behind the speaker...

It is bad placement, as it allows midrange to escape through the port. When midrange reflects off a wall it can be a problem. I know Bag End did so, only they can say why.