Depends on implementation and needs vs size limitations etc.
If it was me I'd probably stuff the ports for the main speakers to make xo/phase slightly easier to deal with, mostly because ported off-the-shelf speakers (<-making assumptions here) is a bit hit-and-miss in terms of port calculations and excecution (<-based on previous experience).
I would most likely build a ported sub myself, if you make a closed box it is somewhat common to need a slightly bigger amp to get equal output, but again: needs and implementation.
If it was me I'd probably stuff the ports for the main speakers to make xo/phase slightly easier to deal with, mostly because ported off-the-shelf speakers (<-making assumptions here) is a bit hit-and-miss in terms of port calculations and excecution (<-based on previous experience).
I would most likely build a ported sub myself, if you make a closed box it is somewhat common to need a slightly bigger amp to get equal output, but again: needs and implementation.
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It depends more on the driver used and the wishes on low extention and space you have than on what is playing higher up in frequency. Ported is easier to bring low, and asks for lower QTS (<0.45) and higher EBP (>50) while sealed is harder to bring real low and asks for higher qts (>0.35) and lower EBP (<100). The section where those two overlap is where drivers are fit for both alignments. These are off course general guidelines, not absolute laws.
And sealed tend to loose a few dB's compared to ported for the same driver and power. They do sound more precise and punchy, and have a much lower group delay. Both can sound very good and very bad, depending on how well they were designed and build. I personally prefer sealed.
And sealed tend to loose a few dB's compared to ported for the same driver and power. They do sound more precise and punchy, and have a much lower group delay. Both can sound very good and very bad, depending on how well they were designed and build. I personally prefer sealed.
My mains are ported but problem is that they roll off a bit early if I stuff the ports. Also if I use ported subs they become a bit big. That's why I would like to use sealed with ported mains, just wondered if it would work ok.
To be more precise in our advice, we will have to get more info. And like said, it depends on the right driver. For getting a low frequency response sealed, the right driver is essential. And to make it work with your top, we also need to know what you use and it's specs and what kind of crossover (passive, dsp, ...) you plan to use.
And temaad is right, a sealed top is easier to integrate than a ported one. So if you could change the cabinet, it would make things easier.
My main speakers are going to be Troels Gravesen SBA741.
This is a 3 way design with SBA MW19P-8 bass unit which I assume can be in a sealed box as well as ported. If I build it with a 24 litre box and stuff the port it rolls off very early thats what concerns me. I suppose I could build it in a smaller sealed box and and go for a higher QTC, what do you think
Have not decided on sub drivers yet. But as I said I would prefer sealed to keep size down
This is a 3 way design with SBA MW19P-8 bass unit which I assume can be in a sealed box as well as ported. If I build it with a 24 litre box and stuff the port it rolls off very early thats what concerns me. I suppose I could build it in a smaller sealed box and and go for a higher QTC, what do you think
Have not decided on sub drivers yet. But as I said I would prefer sealed to keep size down
Well, if you use his design, you best also use his bass module and driver as they are matched. Changing it will make it worse. And you can't just make a closed cabinet of the same size for that midbass driver he is using, as it won't be fit for it. Better stay on his design plan with other words.
I take your point but just dont like the shape and the fact that the SBA 741 subs are ported.
Would like to build the 741s but will the fact that I build them sealed be a problem, I could reduce the volume by not making them so deep.
Would like to build the 741s but will the fact that I build them sealed be a problem, I could reduce the volume by not making them so deep.
My suggestion is not to change the shape of the SBA741 enclosure.
What you could do is closing the upper part of the bass volume (behind the midrange) and use that for mounting the crossover.
You will have some 6 liters less that way which is perfectly fine to cut bass of the MW19 a bit.
Stuff the port to make the enclosure aperiodic, or sealed; you can easily experiment.
Additional subwoofers also depend on your requirements: for HT maybe ported subs work well; for music reproduction I'd go for sealed subs.
At the moment I very much enjoy a pair of ~ 80 liter aperiodic damped subs with Scanspeak 26W/8534 drivers; excellent sounding bass (high Qm!).
What you could do is closing the upper part of the bass volume (behind the midrange) and use that for mounting the crossover.
You will have some 6 liters less that way which is perfectly fine to cut bass of the MW19 a bit.
Stuff the port to make the enclosure aperiodic, or sealed; you can easily experiment.
Additional subwoofers also depend on your requirements: for HT maybe ported subs work well; for music reproduction I'd go for sealed subs.
At the moment I very much enjoy a pair of ~ 80 liter aperiodic damped subs with Scanspeak 26W/8534 drivers; excellent sounding bass (high Qm!).
You need to redesign the cabinet and crossover if you do that. Top section on cabinet can be the same, but the woofer section needs to be adapted to sealed and the crossover need to be adapted as it's based on the measurements of a ported cabinet of that format. And yes, the cabinet has an influence on how the driver reacts.
Put the M19 in a 8L cabinet (6 is a bit too small, will give a peak in the lower resonance) and crossover at about 150Hz (2nd order or higher) to the sub. without sub it will go to about an F3 of 85 hz and an F6 of 65Hz. When done right this can be a great adaptation.
The Scanspeak 26W/8534G00 is indeed a good subwoofer for this, i use it in a 77L sealed cabinet and it goes to 32Hz (F6) like that which is low enough for any style of music (not for HT maybe). An Alternative can be the 12" SB34NRX75-6 in a 100L cabinet (to stay full SB drivers) which even go lower (F6 of 28Hz).
Note, for a sealed cabinet, it's not the F3 that counts, but the F6 as the slow high pass slope of the cabinet and the room will fill up the bas more than with a ported/TL/Horn where the F3 is important.
Put the M19 in a 8L cabinet (6 is a bit too small, will give a peak in the lower resonance) and crossover at about 150Hz (2nd order or higher) to the sub. without sub it will go to about an F3 of 85 hz and an F6 of 65Hz. When done right this can be a great adaptation.
The Scanspeak 26W/8534G00 is indeed a good subwoofer for this, i use it in a 77L sealed cabinet and it goes to 32Hz (F6) like that which is low enough for any style of music (not for HT maybe). An Alternative can be the 12" SB34NRX75-6 in a 100L cabinet (to stay full SB drivers) which even go lower (F6 of 28Hz).
Note, for a sealed cabinet, it's not the F3 that counts, but the F6 as the slow high pass slope of the cabinet and the room will fill up the bas more than with a ported/TL/Horn where the F3 is important.
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The way I described would leave the MW19 with some 15 liters; that's OK for around 60 Hz or so when sealed.
I would not crossover the MW19 with a high pass, but instead "fill in" the bottom octave with the subwoofers. The MW19's are rather potent already in the bass department.
The 741 crossover is not complex; leave it as is and you will be almost or completely there where you want to be.
I would not crossover the MW19 with a high pass, but instead "fill in" the bottom octave with the subwoofers. The MW19's are rather potent already in the bass department.
The 741 crossover is not complex; leave it as is and you will be almost or completely there where you want to be.
Hi daanve thanks for your input.
Your idea seems good to me I will only be using the speakers and subs for music so sealed seems best.
I think it will be best if I build the SBA741 as a sealed design as I dont rerally want a rear port even if it is aperiodic.
The space for the SBA MW19 bass units will probably end up a bit more than 18 litres though as I wll have to put some acoustilux etc in as per TGs design and this will make the virtual volume a bit more. Will this matter much.
My idea is to have a couple of 8 inch subs combined with the SBA MW19 I think the bass output should be good.
Your idea seems good to me I will only be using the speakers and subs for music so sealed seems best.
I think it will be best if I build the SBA741 as a sealed design as I dont rerally want a rear port even if it is aperiodic.
The space for the SBA MW19 bass units will probably end up a bit more than 18 litres though as I wll have to put some acoustilux etc in as per TGs design and this will make the virtual volume a bit more. Will this matter much.
My idea is to have a couple of 8 inch subs combined with the SBA MW19 I think the bass output should be good.