Ported and sealed in the same enclosure

presscot

Member
2010-07-27 12:24 pm
I’m going to build a pair of floor-standing speakers where a pair of woofer will be installed per cabinet. For the woofer, it can be used both ported and sealed. So, what if I am going to build the speaker that has ported and sealed in the same enclosure. Each woofer will be placed in its individual chamber. Is it important to tune the sealed and ported chamber at the same frequency? Do the sound from ported and sealed be the same or concordant to each other, in both tuned at same and different frequency? Thank you in advance.
 
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presscot

Member
2010-07-27 12:24 pm
Why not use two woofers back to back and halve the size of the bass cabinet?

Do you mean to the bandpass enclosure? I used to consider it too. But as I’d like to build the floor-standing. I’d like the cabinet to be as tall as possible - in 100-150 cm. range. So I consider to use the sealed type. But as computed by online calculator, my woofer can be used with both ported and sealed. So I’m interested to build it both in a cabinet to gain their both advantages, also the disadvantages. :)
 
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Interesting that you posted this. I just recently read about a designer at the Munich HighEnd 2019 show that did something similar. He used two 4ohm woofers in a sealed configuration and one 8 ohm woofer ported in the same cabinet. Hi FI Compass give it an award for best 3+ way speaker. I thought it goes against convention, but what do I know.
Munich HighEnd-2019. Who is the best? | HiFiCompass
 
Interesting that you posted this. I just recently read about a designer at the Munich HighEnd 2019 show that did something similar. He used two 4ohm woofers in a sealed configuration and one 8 ohm woofer ported in the same cabinet. Hi FI Compass give it an award for best 3+ way speaker. I thought it goes against convention, but what do I know.
Munich HighEnd-2019. Who is the best? | HiFiCompass

Who can afford $30,000.00 speakers? It seems a little out of place here...kind of like Consumer Reports reviewing a Lamborghini. ;)

Mike
 

jReave

Member
2012-10-30 4:34 pm
I'm going to echo what DickHertz said:

I Why not put two woofers in separate ported enclosures, and fabricate plugs for the ports to use as you see fit?

You get more flexibility this way which has at least 2 advantages:

1- You're better able to tune the bass response to the room - if the speakers are in a small room, plug one (or both) ports to reduce the LF room gain for less boominess or leave them both ported for more bass in bigger rooms.

2- Again, plug 1 or both ports if you occasionally come across recordings that are too bass heavy.

Of course, that's if you have enough room in your design for the larger box volumes that 2 ported woofers will need compared to the sealed ones.

I have a pair of speakers with 4 woofers per side separated into 2 ported chambers and this has worked out very well for me. I have one favorite CD in particular that I recorded that for some reason or another is loaded with extra bass. Every time I play it, I grab a couple of pairs of socks and stuff them into 1 of each speaker's 2 ports and then it's just about perfect.

Not an original idea though - I stole it from PSB speakers.
 
The speakers I was referring to were the Menara.
"...a demo concept-loudspeakers developed by the Ulrik Shmidt - an engineer of Danesian Audio company, whose main task was to demonstrate the potential of a new SB Acoustics midrange speaker MD60N-6 with a silk 2.5" dome. I was very surprised and it was exactly the case which show there is no need to pay tens thousands of dollars and to chase the big-name brand to get a good sound. Crazy quality/price ratio and well deserved reward!..." -HIFI Compass.

Anyway, the point was to provide the OP with example of a design similar to what he plans to do.
 
Be forewarned. The impedance curves for the two enclosures will be very different if one is ported and the other sealed. You run the risk of overdriving one speaker at some frequencies while underutilizing the other, and the power sharing between the two will vary with frequency. You usually want both sharing the load equally at the lowest frequencies where excursion is highest. That will not happen with a sealed/ported combo.
 
Be forewarned. The impedance curves for the two enclosures will be very different if one is ported and the other sealed. You run the risk of overdriving one speaker at some frequencies while underutilizing the other, and the power sharing between the two will vary with frequency. You usually want both sharing the load equally at the lowest frequencies where excursion is highest. That will not happen with a sealed/ported combo.

This is really dependent on the output impedance of the amplifier, and the associated impedances up until the drivers, such as cable and inductor resistance/impedance. Combined sealed/ported has definitely been done before to good effect.

Using high impedance cables/crossover or an amp with a higher output impedance could definitely have the effect explained here.

Cheers,

Matt.