Subwoofer suggestions

[Palmspar]

Most people buying speakers don't know any better. They listen to the speakers and the one with the most bass and top end sizzle typically sounds better to them, not knowing that ported speakers can be more difficult to get phase aligned with a subwoofer.

KEF does provide port plugs with some of their speakers. I don't know whether any other speaker manufacturers also provide plugs.

Arendal provide plugs, for the thx label the speaker must rolloff arround 80hz on its one.

 

[Ze Frog]

It depends. A Qts of 0.40 works well for a second-order Chebychev equal ripple response (Qtc = 0.8) acoustic suspension speaker. A Qts of 0.40 also works well for a vented enclosure with a SC4 alignment with a QL of 7.


I have never used a woofer with a Qts anywhere near that high. The last acoustic suspension speakers I built myself used woofers with a Qts of around 0.33 for a second-order Butterworth alignment (Qtc = 0.707). The last ported speakers I built myself used woofers with a Qts of around 0.40 for a SC4 alignment (QL = 7).

Sorry, was a typo, meant 0.5, maybe I've been misunderstanding the design philosophy somewhat as I'm certainly no expert. My understanding was a higher Qts allows for a smaller box to be used, maybe I've been attributing that to other things as well where it's not needed.

 

[terryforsythe]

Sorry, was a typo, meant 0.5, maybe I've been misunderstanding the design philosophy somewhat as I'm certainly no expert. My understanding was a higher Qts allows for a smaller box to be used, maybe I've been attributing that to other things as well where it's not needed.

Higher Qts typically is used for infinite baffle (e.q., open baffle speakers, in-wall speakers, speakers for car doors, etc.). I prefer a Qts around 0.4 for bass reflex designs, and a Qts a little lower for acoustic suspension, due to the bass alignment profiles. If, however, a subwoofer is being used and the speakers are being crossed over at a higher frequency (e.g., an octave higher than their in-box resonant frequency), the Qts of the woofer is less critical.

 

[rlal]

I personally think it will be fine. The main limitation you will have is that Dirac will not be able to calibrate them independently. You can do that manually to a certain degree. You'll need to adjust their levels to 72db each at whatever the Dirac calibration volume is. So you achieve 75db total when they are being calibrated together (or whatever the calibration spl is supposed to be). Then You'll need to set their phase angles manually with the main left/right speakers. You can do this with REW by playing a tone at the crossover frequency to both the main speaker and one sub then adjusting the phase angle to the max spl REW records. Repeat with the second sub. Enjoy!

Thanks for your reply.
My Arcam 850 cannot calibrate the sub independently. I used to do a factory reset and never used to do
manual level matching before doing Dirac. So before doing Dirac you want me to do that or after Dirac?

I can do the one you mentioned using REW.

 

[Beershaun]

Thanks for your reply.
My Arcam 850 cannot calibrate the sub independently. I used to do a factory reset and never used to do
manual level matching before doing Dirac. So before doing Dirac you want me to do that or after Dirac?

I can do the one you mentioned using REW.

1) check the Dirac instructions to find out what spl level your subs should be at combined when Dirac runs the calibration. (Usually it's 75db)
2) in order to make sure that the combination of the two subs is at 75db you need to subtract 3db for each sub and set your starting sub level on your individual subwoofers. So if it's 75db when calibrating with both subs running, you want to set each sub manually so they are at 72db spl at the volume level that Dirac runs at. That will help you account for the difference in output from your 12" and 15" subs.
3) then run Dirac and it will figure out the overall sub level output with the two running together.
4) for time alignment, since Dirac can only set one time alignment for your sub output you will need to tweak it manually after its complete.
5) so after Dirac is finished, run a test tone at the crossover frequency (typically 80hz or whatever Dirac ended up setting). One sub at a time (turn off the other while setting the phase angle). Use rew or a spl meter at the listening position and slowly adjust the phase angle knob on one subwoofer until you reach the loudest spl at the listening position. That will mean your subwoofer delay is aligned with your main speaker. Then do the same for the second sub.

 

[YoJimbo]

Most people buying speakers don't know any better. They listen to the speakers and the one with the most bass and top end sizzle typically sounds better to them, not knowing that ported speakers can be more difficult to get phase aligned with a subwoofer.

KEF does provide port plugs with some of their speakers. I don't know whether any other speaker manufacturers also provide plugs.

I bought two Hsu subwoofers over 20 years ago. Each had two ports and two plugs, and I had the option of zero, one or two plugs, each giving a different frequency graph, of course. I don't know if Dr. Hsu is still doing this.