Side firing bass designs - Pros & Cons?...

The pros are a narrower front baffle, for better imaging, like a mini-monitor. The cons are they require a little more care in setting up. If the woofers fire into the wall they can overpower the sound. Many manufacturers are going this direction now. Audio Physics, Canton and my Vienna Acoustics to name a few. They try to better blend a monitor/subwoofer in one cabinet. The days with all front firing drivers in a rectangular box seem to be dwindling. Even speakers that have all forward firing drivers tend to not be rectangular, going with a form of pyramid shape. The main goal is to make the front baffle as small as possible to eliminate early reflections that can muffle the sound a tad. My Strauss' have 10" side-firing woofers crossed over at 70 hz. So they are basically subwoofers, and low frequency is not directional, meaning humans cannot detect where the sound is coming from. That is why subwoofer placement isn't as critical as speaker placement. I have my woofers facing in. I've found that when facing out they had too much wall reflection and the bass was a little overpowering and slow. It is tighter and quicker when firing in, IMHO. My previous speakers had 10 forward firing woofers and a wider front baffle (12" compared to 7.7" wide)than my current ones. My current speakers image better, meaning I can locate instruments within the soundstage better than with the other ones. They almost image as well as the best small monitors, but with much better bass. I hope this was somewhat helpful.

Regards,
John

If memory serves, frequencies below 200 Hz tend to be perceived as non-directional -- you can't tell where they are coming from. John is correct that a smaller front baffle leads to improved imaging, but some manufacturers compensate for that by utilizing material that absorbs high frequencies, like felt, on the surface of the baffle combined with rounded baffle edges to reduce reflections. If you are a time and phase coherence proponent, I would think it would be harder to design that into a side firing speaker. While you may not be able to tell the source of the low bass, it may take a lucky confluence of factors (e.g., room acoustics and layout) to compensate for the reliance on reflected sound. From my experience with Def Techs, that design could also lead to some problems with a smooth transitioning from mid bass to low bass. You're wise to suggest there are pros and cons -- there are with all speakers.

Using one woofer or multiple woofers on one of the sides of a cabinet can make placement very difficult. Using a woofer on opposing sides of the cabinet makes placement LESS difficult. This is because each driver excites the room in a different manner and direction, causing a more even overall response rather than just one major point of excitation in one direction.

If one has the computer download speed capabilities, i would suggest downloading and reading the owner's manual for the AR 9's found at this link. Be forewarned, it is a 53 page PDF file. As such, it will take a bit of time to download. Having said that, it is worthwhile as they provide several pages of charts comparing various speaker placements using their side firing design against more conventional front firing designs. Obviously, this was used as marketing material and should be taken with a grain of salt, but one can learn from some of the info presented in this manual. Sean
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click to download 53 page AR 9 pdf file

PS... When is the last time you saw a 53 page owner's manual for a speaker ???

Sean -

Thanks for posting the AR 9 owner's manual link! Great info in the room acoustics section. Methinks the folks at AR tore a page from the back of Roy Allison's notebook.

Another speaker that used a room-boundary-conscious woofer system design was the Snell Type A.

Back in '86 I built a pair of speakers using a 30" tall Gold Ribbon Concepts planar driver and a pair of 7" Focal woofers. To keep the front baffle area to a minimum, I mounted the drivers on the side. It was kinda cool looking - from the front, all you saw were the ribbons. The woofers were physically about 1/6 wavelength farther away than the ribbons at the 200 Hz crossover point, which was negligible. Both the woofers and the ribbon were loaded into transmission lines. If by any chance you have the 4/86 issue of SpeakerBuilder magazine, you can see a picture of it. In retrospect there were some radiation pattern discontinuities that I wouldn't tolerate today, but at the time I didn't know any better. Still, they didn't suck too bad.

Duke