40hz ratings/speaker response

Clueless, thanks, that was where I read it. I just couldn't remember where it was. Also, I noticed he was pretty rough on quarter wave pipes in that article. But, if you really tear any design apart that far, then nothing will really hold up too well to that kind of scrutiny. I'm still thinking that I can get a "happy medium" of decent bass-boost, and limited notch-effects from comb-filtering, from the Voigt Pipes. He didn't even mention the "baffle-step" effect of the Voigt Pipes, where the narrow baffle reinforces the higher freq's and you get a drop-off where the baffle is no longer wide enough to reinforce the lower ones. I've got a couple of tricks up my sleeve to handle this, without resorting to a compensation circuit that destroys efficiency.

Joeb, the point that I was trying to make was that sound waves can't be heard if they don't have room to develop at least one full cycle. For simplicity sake, one cycle of sound meanders like the letter S. According to the laws of physics, one full cycle of sound at 40 cycles per second needs 28 feet to develop. That is why I thought 40 cps was the lower limit for a normal listening room. One would have to be rich to have a room large enough to hear deeper tones. However, Bob at inpepinnovations said that only one half of the space required for a full cycle is required in order to hear a low frequency. One half of a full cycle would look like the letter C instead of the letter S. Assuming that the revised theory is correct, 40 cycles per second (hertz) could be heard in a 14 foot room, not a 28 foot room as I first proposed. Also, sound at 25 hertz would only require a 23 foot room, not a 45 foot room. In short, my theory was shot down.

Allow me to propose an anology to explain the limitation of the 40 hertz rated speaker. Imagine a soprano singer trying to sing bass. The vocal cords are too short to develop the lower frequencies, and thus distortion sets in. As you proposed, let's imagine that the soprano singer tries to sing bass even louder on the second try. The distortion would be louder and more pronounced, but the lower octave would never be reached. If the soprano singer continues these attempts, her vocal cords would be destroyed, just as a speaker would be destroyed in the same attempt.

Hi Twl:

Was just going through this site as I saw your post back here. You might enjoy??? ("God-awful" voigt pipe from the club of Norway", he says) it if you haven't already been there. I'm not sure what to make of it. I'm messing around with a few of the same Qs you are it seems.

www.geocities.com/rbrines1/index.htm

Cheers,
Ryder

Clueless, pipes are already made with a S0 of zero. Drivers are on the way, but not here yet. Everything is ready to just plug in the drivers. Apparently, Brines is really hot on the Mathcad program, but not too interested in using the right drivers for the Voigt pipes. He used everything but the Lowther, and these were designed to use the Lowther. So he takes these pipes, and plugs a much smaller driver into them and complains about the results. Now, I don't doubt for a minute that I will have issues with dips at the resonant points. But, whether the problems will be as bad as he says remains to be seen. If they are, then I'll try a few things, and may even shorten the pipe to open up the S0(narrow tip)area. But, I have read alot of testimonials that this pipe design sounds good. So we will have to just try it out and see.

Being a latecomer, I have the benefit of the earlier postings.
Sdcampbell, Gboren are right to the point with reading the specs and the importance of interpreting +/- 2 or 3dB. I understand that genuine spec ratings are recorded with some sort of standard reference equipment, sensor mounted 1m on axis infront of the speaker driven with some standard frequency sweep signals, in an anechoic chamber. So there is some standard measurement in the speaker manufacturing industry.
Red I love the climax of your soprano story! The room size resonance effect in our real listening area does distort the overall sound that we perceive, and resonance must be controlled with every practical means possible.
My own experience is that there is vast difference in bass reproduction between my M.Logan Aerius (45Hz +/-3dB) and my later acquired Dynaudio A72 (28 +/-3dB) despite what some of the above posts opined. With the exact same gear I had been using, the Dyns came out with so much ooomph(body)and deep sound staging, a big step closer to like "being there" feeling compared to the Aerius. All along I thought Aerius'45Hz is low enough for reproducing whatever in the CD; I was wrong!
I believe that when our ear response starts to roll off at some point, the guts (feeling) takes over down to even lower frequencies.