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

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 ???

Duke: Roy Allison used to work for AR, hence the similarities in design. For that matter, so did Ken Kantor, who designed / helped design some of the NHT stuff. From what i understand, the woofers used in the 9's were made by the same company that makes the NHT 1259 woofer. Both drivers work best in big, low Q sealed boxes, which is what i like anyhow : )

Slappy: Bass doesn't become "non-directional" until pretty low. I think that even at 100 Hz, one can still pretty well "localize" the point of origin without much fuss if they know how to listen. This probably has a lot to do with the harmonics that the driver is radiating and the distortion too. Sean
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Dawgbyte: I mentioned the Coincident Technology aka Israel Blume's speakers. Glad you liked that website as i'm sure it is loaded with info.

Jmcgrogan: Thanks for the reminder. I'm sure that there are other speakers out there that i overlooked. I hope nobody feels slighted if i didn't mention the brand that they are running with side firing woofers : ) Sean
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The Vienna Acoustics speakers are VERY placement sensitive from what i remember. Can't remember the model that i tinkered with, but it was a big floorstander with woofers on the side. The bass reminded me of Legacy's, which is to say, loose, flabby and lacking in definition. My Dad really loved them. Then again, he already owns Legacy's. I'm working on that though : ) Sean
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Lrsky: Your observations pertaining to distortion are right on the money. A large part of the distortions that we hear are THD, which are comprised of higher frequency harmonics of the orignal signal. Facing the drivers away from our ears "dillutes" the percentage of those higher frequencies that we hear. This causes them to blend in with the other signals being reproduce, minimizing their effects and noticeability.

As a side note, it is the harmonics of a lower frequency signal and the "leakage" through the crossover that allows us to localize low frequency signals. The more effectively that one can minimize the distortions that we hear and the harmonic overtones that the driver generates, the less likely you are to locate the source of bass. Obviously, facing drivers away from you and running a sharp crossover at a very low frequency is about the best that one can do in this respect.

As far as output levels go, if you want low bass at high volumes, you've got to move a LOT of air. While one can do this with a few drivers that can provide huge amounts of excursion, long excursion drivers tend to have their own problems and introduce distortions into the system. The other approach is to use multiple woofers in some type of array. If the array loads the room in multiple directions, you can achieve great bass output while exciting the room nodes in a more natural manner.

As a side note, the mains of my HT system each have a side firing 12" on opposing cabinet walls. The surrounds have side firing 10's arranged the same way. My bedroom system uses down-loaded subs that are currently crossed at 65 Hz and my main system uses four dipolar 12's per side in sealed low Q boxes. My office system radiates in a 360* horizontal pattern from a single driver, so it too loads into the room differently than most "conventional" speakers. The only "normal" speakers that i'm currently running at the time are front loaded horns and event these aren't "direct radiators" so to speak.

I'm also building s system for a friend that uses eight 12" woofers per cabinet. The baffles are as narrow as possible and make use of a very large line array of mid-woofers and tweeters ( power handling, high sensitivity, lower distortion due to reduced excursion and more linear radiation pattern into the distance ). Flanked on each side of the baffle sloping backwards will be four 12's per side in a stuffed but open backed cabinet ( damped open baffle ). I had to look carefully at the electrical characteristics of the woofers to do this, but i think that it will work quite well. Sean
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You'll get comb filtering no matter what you do when using multiple driver arrays, but that can minimized by careful design and wiring. I ran across a website that was mentioned on Madisound when doing research on line array's that goes into detail regarding comb filtering, driver size and spacing, crossover frequencies and slopes, etc... I printed it out as it was worth having around. If i can remember correctly, the website was run by a gentleman by the name of James R. Griffin.

While i can't find his specific website, i was able to find one that had his work along with that of a lot of other line array advocates all compiled together as various downloads. At least some of Jim's work can be found here and is titled something to the effect of a "linus array". Sean
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Line Array information

Other than the AR 9's, 90's, NHT, Vienna Acoustics and Coincident Technologies, i can't really find any other speakers that made use of side firing woofers. I'm not counting Allison's and DCM Time Windows, as the woofers weren't so much "side firing" as the woofers were not side mounted so much as the cabinets were twisted sideways. Other than that, the only other thing that i can find was that EPI had a speaker that looked quite similar but used dual passive radiators where the 9's and 90's had active radiators. These were driven by one active 10" that was mounted up where the AR's mounted their 8" mid-woofer. If i can recall correctly, i think the EPI was a model 500 and made use of their popular and good sounding inverted dome.

Other than that, there might have been another company out of Europe selling a speaker with side firing woofers. I think i remember seeing some in one of Jerry Raskin's Needle Doctor advertisements, but i'm not certain. I thought i saw something about it using a Hiquphon tweeter, etc... Sean
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PS... I'm not including the Fluance ( Flatulence ?? ) speakers as found on Ebay in this list. I have a hard time believing that someone can build and market 4 and 5 driver towers of any quality for well under $300 per pair. Then again, who knows. Maybe these would shock me in regards to what they offer for the money. I kinda doubt it though : )