Ported, Sealed or Transmission Line

Infinite Baffle sounds like a cable manufacturer's technical White Paper. :o)

It's also what you get when you set a speaker in a wall, or in a floor like some subwoofers of the fifties. ( Think of the low end from an 18-inch EV hung just under your feet! )

The term means that the driver's back wave is " baffled " as it tries to come round and cancel out the front wave, which is in opposite phase. It's a British term and in England the baffle of a speaker is its front panel. When a speaker is mounted in a wall, the back wave has, for practical purposes, an infinite distance to travel before it can cancel anything out.

Of course all dynamic loudspeaker designs try to either eliminate or control the cancellation effect, which is most serious in the bass. That's why we put drivers in boxes in the first place.

Although I am not sure Sean meant to suggest that the straw trick for reducing port turbulence or "chuffing" is pure snake oil, I quite agree with him that you need to do some reading. There is much more to this question than you will conceivably get here, and you need a balanced view of your own.

That said, I am just as willing as anyone else to display my ignorance in public.

Any speaker design can result in a pleasing sound or not, depending on how it is implemented. Every design is built around tradeoffs--you win on the roundabouts and you lose on the swings, as the British say. Sealed enclosures have a relatively low resonant 'Q' but the actual resonant frequency will be higher than that of an equal-sized, properly ported box. Sealed box designs need more amplifier power, on the whole, because the cones have to work against the very stiff spring of the air trapped inside the box.

Knew that ? Great stuff. There's more. My supposedly humble opinion is that until you appreciate the tradeoffs involved in any audio design, you don't really appreciate the design.

Thanks for the correction, Metralla.

I knew about the spider design ( and the more resilient cone surround ) but I hadn't absorbed the back wave concept. Needed more stuffing, possibly.

Sean, thanks for the detailed description of your setup. It sounds absolutely fascinating.

I certainly agree about TL being the best way to deal with the back wave if you are going to build a vented design--that is, for all the little I know about it. I was too ignorant and ill-equipped to try designing a TL or even a good reflex in my own first try so I opted for what G.A. Briggs called a distributed port (DP), in his "Cabinet Handbook" from 1955. This is close to an aperiodic--basically you calculated your port area for the bass resonance of the system and divided it up into ten or so slots, damped with felt. Great DIY design, very forgiving, lower Q made it less critical to hit the system resonance right on in the port and box volume calculations. Well below your league.

Reading Briggs' book you got the feeling he was a bit wistful about the infinite baffle. He didn't talk about it much but he liked it. Maybe it was because as a company, Wharfedale could never have sold more than drivers for the design. I bet he would have liked your setup.

I love the variety of enclosure designs. Almost as many as there are for tube amps in Japan. I once saw one for a very short TL ending in a ported box which was said to get great bass out of a 4 or 5-inch paper woofer.