• WANTED: Happy members who like to discuss audio and other topics related to our interest. Desire to learn and share knowledge of science required as is 20 years of participation in forums (not all true). Come here to have fun, be ready to be teased and not take online life too seriously. We now measure and review equipment for free! Click here for details.

Mixing sealed with ported

stunta

Addicted to Fun and Learning
Joined
Jan 1, 2018
Messages
618
Likes
386
Location
Boston, MA
#1
Are there any known issues with mixing sealed speakers/subs with ported speakers/subs in the same system? If so, what are they and why? Besides getting them to match by replacing equipment, is there any other way to mitigate the issues, if any?

Thank you!
 

Ron Texas

Major Contributor
Joined
Jun 10, 2018
Messages
1,215
Likes
709
Location
Equidistant From Everywhere
#2
Are there any known issues with mixing sealed speakers/subs with ported speakers/subs in the same system? If so, what are they and why? Besides getting them to match by replacing equipment, is there any other way to mitigate the issues, if any?

Thank you!
If you have a high pass filter, the ported stand mount speakers will roll off before the port has a lot of output.
 

Blumlein 88

Major Contributor
Joined
Feb 23, 2016
Messages
5,781
Likes
4,858
#3
I don't know. So why am I replying? Theoretically it might matter or not. Is that helpful?

Sealed box speakers usually roll-off their low end response at 12 db/octave (other tunings are possible). Ported speakers will roll off at 24 db/octave. If you are operating near the low end roll off of the main speakers how you crossover to the sub might matter as the crossover combined with the main speaker roll off will effect response there.

So for instance if your main speaker rolls off at 40 hz using it with a crossover that is implemented at 80 or 100 hz isn't going to cause real trouble. If it rolls off at 100 hz and your crossover does too, it might make for a region where response is not what you'd expect. Say ported fast roll off at 100 hz plus 12 db xover at 100 hz. You'd get a 36 db/octave roll off which may not match with a sub that is rolling off the high response at 12 db/octave.
 

stunta

Addicted to Fun and Learning
Joined
Jan 1, 2018
Messages
618
Likes
386
Location
Boston, MA
#4
Thank you for the replies. My speakers are sealed and the two Rythmik mid-bass modules I have are also sealed. The REL sub is ported. I am using minidsp and configuring crossovers externally and the xover is far off from the speakers' naturall roll of. I've used the same 24db slope for all.

Speakers: 200 Hz (these speakers are rated at -6db at 54Hz)
Rythmiks :50 - 200 Hz
REL sub: 50 Hz

So I guess I should be fine?

Also, besides the roll-off, is there any other issue?
 

Blumlein 88

Major Contributor
Joined
Feb 23, 2016
Messages
5,781
Likes
4,858
#5
I don't think so. Looks like you are all good to me. Those Rhythmiks are nice a friend has some of them.
 

stunta

Addicted to Fun and Learning
Joined
Jan 1, 2018
Messages
618
Likes
386
Location
Boston, MA
#8
Great. Thanks again.

Holy crap, @mitchco, with that rig are you listening to music or feeling it? :D

I love the Rythmiks. I've not understood what "tight" bass means until had a pair of these FM8s. At some point, I'd like to replace my REL with a Rythmik. The REL is not bad though and goes really now.
 

andreasmaaan

Major Contributor
Patreon Donor
Joined
Jun 19, 2018
Messages
3,350
Likes
2,461
#9
There’s no problem at all with what you’re doing. Going from a ported main or midbass to a sub can be difficult (but feasible), but going from a sealed midbass to a ported sub shouldn’t be problematic. The more control you have over the crossover filters the better. How are you doing it?
 

Juhazi

Active Member
Joined
Sep 15, 2018
Messages
217
Likes
156
Location
Finland
#12
A BR main speaker might be problematic with low xo to sub, because the port tuning means gradual up to 180¤ phase shift, starting an octave above port tuning frequency. A crossover slope makes phase angle shift too and usually we want the LP andHP phases to match. Most subwoofer amps have a knob to set phase (it means more delay). Distance and room/positioning have a remarkable effect too.

With minidsp or like, still best results come with acoustic measurements, including delay /phase matching! I have found that I must always set delay for main speakers. This is very important the make the sub to disappear and to give the right punch for transients. Making reliable measurements in not easy, but well worth the effort.
 
Last edited:

RayDunzl

Major Contributor
Central Scrutinizer
Joined
Mar 9, 2016
Messages
6,824
Likes
2,942
Location
Riverview, FL
#13
Are there any known issues with mixing sealed speakers/subs with ported speakers/subs in the same system? If so, what are they and why? Besides getting them to match by replacing equipment, is there any other way to mitigate the issues, if any?

My main speakers have sealed twelves, and the adjoining subs (the Cheezewoofers) are ported fifteens, with claimed tuning at 23Hz. The mains measurably go lower, 25Hz or so is the lowest tone I perceive, and I'm not aiming to shake the house.

Of course, as is usual for me, I'm probably doing it all wrong.

I run the sealed woofers full range (cross to panels is 180Hz), and the subs overlap the lower part of the woofer range.

The initial setup step is to balance the unequalized output levels of the six low frequency drivers, and the essential result is each driver runs at -9dB compared to running a single sub or woofer in the range where they overlap, the idea of that is to reduce low frequency harmonic distortion.

With automated "room correction" DSP applied I don't hear or measure any problems mixing the ported and sealed woofage. Nothing weird seems to appear in the amplitude or phase corrections that are calculated and applied.

The next part of the experiment where I would locate the subs in different positions (they adjoin the mains now) still hasn't occurred, being satisfied with the current result, and the subs having little JBLs on top (the sub stack operating as speaker stands for economy operation).
 

andreasmaaan

Major Contributor
Patreon Donor
Joined
Jun 19, 2018
Messages
3,350
Likes
2,461
#14
A BR main speaker might be problematic with low xo to sub, because the port tuning means gradual up to 180¤ phase shift, starting an octave above port tuning frequency. A crossover slope makes phase angle shift too and usually we want the LP andHP phases to match. Most subwoofer amps have a knob to set phase (it means more delay). Distance and room/positioning have a remarkable effect too.

With minidsp or like, still best results come with acoustic measurements, including delay /phase matching! I have found that I must always set delay for main speakers. This is very important the make the sub to disappear and to give the right punch for transients. Making reliable measurements in not easy, but well worth the effort.
Sealed mains also have a gradual phase shift (half the extent of BR) as frequency approaches the box tuning, so this always needs to be taken into account regardless of the box type. However, in both cases the phase shift is generally minimum phase in nature, so an appropriate crossover can be achieved (broadly speaking of course) so long as the resultant frequency responses of both units can be made to match the intended crossover slope - this is of course likely to be harder to achieve without DSP in the cases of a BR box with an intended xover point near the box tuning.

In any case, the OP has sealed mains (or midbass in this case) and a ported sub.

Very good advice re: needing to take phase/delay into account.
 

stunta

Addicted to Fun and Learning
Joined
Jan 1, 2018
Messages
618
Likes
386
Location
Boston, MA
#15
What does BR stand for?

I have Dirac Live doing its thing on the miniDsp, so I am assuming the phase/delay matching is taken care of.
 

Juhazi

Active Member
Joined
Sep 15, 2018
Messages
217
Likes
156
Location
Finland
#17
I have never used any automated corrections like Dirac, rePhase, Genelec GLM, Lyngdorf, Devialet, Anthem, Audyssey etc. what ever. The ones using FIR are said to handle timing/phase including crossover delays, but I wonder.... It is hard for me to believe that those programs would give similar corrections.

Having performed hundreds of in-room measurements of various systems (2.1, 3-way. 4-way) and rooms, I must say that it is an extremely difficult task. Optimizing to one spot is ok, but which spot... measuring response around 40-200Hz even outdoors is painful, and in-room we have six boundaries and often several openings in the those, multitude of reflections and standing waves.

Nearfield with similar distance discrepancy is a good basis for delay/phase match . Then you have to set eq and gain by other measurements. one problem is that sub and woofer spl response at actual placements are different from nearfield and each other, also phase, mainly because of boundary gain.
 
Last edited:

stunta

Addicted to Fun and Learning
Joined
Jan 1, 2018
Messages
618
Likes
386
Location
Boston, MA
#18
I have never used any automated corrections like Dirac, rePhase, Genelec GLM, Lyngdorf, Devialet, Anthem, Audyssey etc. what ever. The ones using FIR are said to handle timing/phase including crossover delays, but I wonder.... It is hard for me to believe that those programs would give similar corrections.

Having performed hundreds of in-room measurements of various systems (2.1, 3-way. 4-way) and rooms, I must say that it is an extremely difficult task. Optimizing to one spot is ok, but which spot... measuring response around 40-200Hz even outdoors is painful, and in-room we have six boundaries and often several openings in the those, multitude of reflections and standing waves.

Nearfield with similar distance discrepancy is a good basis for delay/phase match . Then you have to set eq and gain by other measurements. one problem is that sub and woofer spl response at actual placements are different from nearfield, also phase, because of boundary gain.
I am not technical in this field so I do the best I can with room correction (I have absorption panels, use Dirac) and let my brain correct the rest. Seems to work just fine for me.
 

Similar threads

Top Bottom