Side Firing Woofer

[Rbrockman]

I would like to hear some of your comments and view any links to more research any of you may have regarding side firing woofers in floor standing speakers.

At above what frequency are we able to begin to localize the source of sound?

Thanks for any input

[ThomasW]

Use 100Hz or lower for side firing woofers

[69Stingray]

I think at one time Zaph was working one, haven't read a comment on it in a while so it may of been shelved for the time being. Another option is a powered woofer. If you use a plate amp, you will have an easier time adjusting the level and crossover freq.

Tomas is correct with the 100-Hz, that is the general rule of thumb. I think you can get away with something higher with a side firing woofer because you have a pair of them and even if you can localize it, you are localizing it to the speakers, the same spot as your midrange and tweeter. I would think with a higher X-Over, the side firing woofer could add some “bad” acoustics to the sound with cone break-up modes or port resonances at higher volume.

I think the more difficult part is the integration of the deep male voices. I have not done a side firing woofer (would love to though). I would think you would want your front firing midrange to have some good extension, maybe an F3 of 80 Hz or so. Then you can voice in the side woofer with X-Over between 80-100 Hz and different padding to match to the midrange.

good luck, keep us posted.

P.S.- I have not found much information on designing a side firing woofer, so keep us posted on your results.

[---k---]

There are some commercial designs that go as high as 240 - 260hz. I do not think this is optimum, it is a trade off.

[djg]

Zaph has a BAMTM design integrated with a side firing woofer in a tower. I do not know if it has been built, but it looks very nice.

[Jonniebravo]

Would a design of this type work with side firing "sub"woofers....Jon

[ThomasW]

That in essence what a side-wiring driver is, a subwoofer.

Issues with this idea are getting a large enough cabinet for the driver to play really low. And that the optimal location for the sub may not be the same as the mains

[wkhanna]

I have been giving this idea some thought lately.

However, my design goals are not HT application. Getting any ‘real’ output bellow 30 Hz will, as Thomas stated, be tough without enough box volume.

I am looking for an alternative to adding a sub(s) or base bins, due to a lack of space in my room, and the esthetic requirements demanded by my OWMBO. And, since 90% of their use will be for music, I am willing to compromise on the V low end performance along with the benefits of optimal positioning. As in all designs, compromises must be made in order to meet chosen priorities.

I will be building a set of Neo’s soon, and am looking at the possibility of incorporating a side mounted woofer in the partitioned bottom portion of a tower design in order to maintain the required 9” wide baffle.

Some commercial designs: http://www.signals-superfi.com/lansche.html http://www.audio-dream.ca/technologies.php

[ThomasW]

I think the best approach is using largest possible high excursion driver with a low Vas, then implementing an L/T circuit to help augment the low frequency output.

[Jonniebravo]

Say you are looking at cabinet size roughly the size of the Large Dayton 3Ways,12"-14" wide,49"-51"tall,and 22''-24" deep. It would be possible to squeeze about 160L's for the subs, that would work If the 15" Tempest-X subs were used And leave 30L's or so for the Dayton RS180's up top.What do you think....Jon

[Curt C]

A potential problem and solution for side firing woofer crossovers

Thomas is as always spot on. I thought I share some thoughts of my own that may have some relevance to the topic.

Another potential pitfall is passively crossing a woofer near its resonance. With a 2nd order electrical network, the shunt cap becomes resonant with the woofer inductance and causes a fairly high Q peak in the woofer output. If your thoughts are to bi-amp with a subwoofer plate amp, this issue is not germane, but if you thought of going passive, you might find the following exercise interesting…

Below are plots of the RS225-8 in a sealed enclosure for simplicity. Vented results are similar.

Plot 1 is the modeled response with no LP filter applied. Shown here as a baseline.

Plot 2 is with a textbook 2nd order LP filter at 100 Hz applied. The peak is nearly 5 dB higher than the response of the driver alone, and the low end extension relative to this peak has increased in frequency somewhat. Obviously this will not provide acceptable performance.

Plot 3 is with the LP filter increased to 200 Hz. Moving further away from the resonant frequency of the driver, Q of the system is lower, but the f3 relative to the peak has moved even higher in frequency. This might be a tolerable alignment, but certainly not an optimal one.

Plot 4 The circuit is modified to add a HP shelving circuit prior to the LP network. In this instance: a 350 uF cap paralleled by a 3 ohm resistor. While the low end roll off still exhibits a slightly higher Q, the f3 is now the same frequency as with no filter applied, and sports with a LP frequency of 145 Hz, which IMO would be an acceptable compromise for a side firing woofer.

Similar results should be possible with other drivers as well.

C

[Jonniebravo]

Yes, the Idea would be seperate amplification,such as a plate amp and EQ If required....Jon

[ttan98]

I

Some commercial designs: http://www.signals-superfi.com/lansche.html http://www.audio-dream.ca/technologies.php

These 2 commercial speakers x-over to SIDE FIRING subwoofer around 120Hz. I think max 100Hz x-over is not a strict rule. I think designer can get away with 120Hz and "possibly" 150Hz is an abosolute max.

[wkhanna]

IMHO, the lower the better. < 80 would quell nearly all issues with sound staging during high quality music reproduction. Again, all in my V humble and less-than-educated opinion.

After considering the options, I have decided in the end to pursue the standard Neo configuration in a bottom ported 65 liter curved cabinet configuration based on my firsthand experience with the Nat P in a similar format. Seeing that the Neo is a three-way design, I think my concerns over mid and low end performance are unfounded.

Again, my personal goal is as close to a full range speaker for music within the smallest footprint possible. However, if I were to peruse a side firing option, I would look V closely at a 12" Rythmik with the LT plate amp.